Chiral palladium(0) trans-stilbene complexes: Synthesis, structure, and oxidative addition of phenyl iodide

2730

Organometallics 2005, 24, 2730-2746

Chiral Palladium(0) trans-Stilbene Complexes:

Synthesis, Structure, and Oxidative Addition of Phenyl

Iodide

†

Tim J. Brunker, Natalia F. Blank, Jillian R. Moncarz, Corina Scriban,

†

,†

‡

Brian J. Anderson, David S. Glueck,* Lev N. Zakharov, James A. Golen,

‡

Roger D. Sommer, Christopher D. Incarvito, and Arnold L. Rheingold

6

128 Burke Laboratory, Department of Chemistry, Dartmouth College,

Hanover, New Hampshire 03755, and Department of Chemistry and Biochemistry,

University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093

Received February 17, 2005

The chiral Pd(0) trans-stilbene complexes Pd(diphos*)(trans-stilbene) (diphos* ) (R,R)-

Me-Duphos, (R,R)-Et-Duphos, (R,R)-i-Pr-Duphos, (R,R)-Me-BPE, (S,S)-Me-FerroLANE, (S,S)-

Me-DuXantphos, (S,S)-Et-FerroTANE, (R,S)-CyPF-t-Bu, (R,S)-PPF-t-Bu, (R,S)-BoPhoz) and

Ni((R,R)-Me-Duphos)(trans-stilbene) were prepared by NaBH(OMe)

3

reduction of the cor-

responding M(diphos*)Cl compounds in the presence of trans-stilbene. The rate of oxidative

2

addition of phenyl iodide to the stilbene complexes, which gave Pd(diphos*)(Ph)(I), depended

on the ligand (larger for increased ligand bite angles and reduced steric bulk) and was

markedly faster than oxidative addition to mixtures of Pd(dba)

Pd(diphos*)(Ph)(I) were prepared independently by treatment of PdL

PPh ) with diphos*. Oxidative addition of PhI to the complexes M((R,R)-Me-Duphos)(trans-

stilbene) occurred in the rate order Pd > Ni . Pt. The complexes Pd(diphos*)Cl , Pd(diphos*)-

trans-stilbene), and Pd(diphos*)(Ph)(I), as well as some analogous Ni compounds, were

structurally characterized by X-ray crystallography.

2

and diphos*. The complexes

2

(Ph)(I) (L ) TMEDA,

2

(

3 2

)

2

(

7

Introduction

Pd(0) complexes are catalysts for many synthetically

example, Pd(diop)(ethylene) and the analogous dppe

8

complex readily decomposed in solution in the absence

of ethylene, and in Pd(dppf)(methyl acrylate), rapid

exchange of free and bound olefin occurred on the NMR

time scale. However, the sterically demanding alkyl-

phosphine complexes Pd(R2PCH2CH2PR2)(C2H4) (R )

t-Bu, i-Pr) were stable in solution in the absence of

1

valuable reactions. The commercially available zerova-

lent PdL4 (L ) PPh3) is often used as a catalyst

precursor. However, for other phosphines and diphos-

phines, catalysts are commonly produced in situ. When

precursors such as Pd(OAc)2 are used, catalyst produc-

tivity and selectivity depend not only on the properties

of the ligand but also on the details of the activation

9

10

ethylene.

In addition to stabilizing Pd alkene complexes, related

chelating alkylphosphines might be useful for catalytic

reactions in which it is crucial that the diphosphine does

not dissociate from the metal, even in the presence of

an excess of competing ligands. Such processes include

2

step, reduction of Pd(II) to Pd(0). Using the zerovalent

precursors Pd(dba)2 and Pd2(dba)3‚CHCl3 (dba ) diben-

zylideneacetone) avoids this complication, but the acti-

vated olefin dba often binds tightly to Pd, slowing

3

4

oxidative addition, and it can undergo side reactions.

(5) (a) Chetcuti, M. J. Nickel-Carbon π-Bonded Complexes. In

Comprehensive Organometallic Chemistry; Abel, E. W., Stone, F. G.

A., Wilkinson, G., Eds.; Pergamon: Oxford, U.K., 1995; Vol. 9, pp 107-

192. (b) Davies, J. A. Palladium-Carbon π-Bonded Complexes. In

Comprehensive Organometallic Chemistry; Abel, E. W., Stone, F. G.

A., Wilkinson, G., Eds.; Pergamon: Oxford, U.K., 1995; Vol. 9, pp 291-

90. (c) Young, G. B. Platinum-Carbon π-Bonded Complexes. In

Comprehensive Organometallic Chemistry; Abel, E. W., Stone, F. G.

A., Wilkinson, G., Eds.; Pergamon: Oxford, U.K., 1995; Vol. 9, pp 533-

Replacing dba with less functionalized olefins might

limit these problems, but little is known about simple

alkene complexes of Pd(0), in contrast to the well-

developed chemistry of Ni and Pt.⁵^,⁶Such Pd compounds

have been reported to contain labile alkene ligands. For

3

5

88.

*

To whom correspondence should be addressed. E-mail: glueck@

(6) For other examples of Pd(0) alkene complexes, see: (a) Fawcett,

dartmouth.edu.

J.; Kemmitt, R. D. W.; Russell, D. R.; Serindag, O. J. Organomet. Chem.

1995, 486, 171-176. (b) Junker, J.; Reif, B.; Steinhagen, H.; Junker,

B.; Felli, I. C.; Reggelin, M.; Griesinger, C. Chem. Eur. J. 2000, 6,

3281-3286.

†

Dartmouth College.

University of California, San Diego.

‡

(

1) Tsuji, J. Palladium Reagents and Catalysts. Innovations in

Organic Synthesis; Wiley: Chichester, U.K., 1996.

(7) diop ) O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphos-

(

2) Strieter, E. R.; Blackmond, D. G.; Buchwald, S. L. J. Am. Chem.

Soc. 2003, 125, 13978-13980.

3) (a) Amatore, C.; Jutand, A. Coord. Chem. Rev. 1998, 178-180,

phino)butane. Hodgson, M.; Parker, D.; Taylor, R. J.; Ferguson, G.

Organometallics 1988, 7, 1761-1766.

(

2 2 2 2

(8) dppe ) Ph PCH CH PPh . Paonessa, R. S.; Prignano, A. L.;

5

11-528. (b) Tschoerner, M.; Pregosin, P. S.; Albinati, A. Organome-

Trogler, W. C. Organometallics 1985, 4, 647-657.

(9) dppf ) Ph PC FeC PPh . Jutand, A.; Hii, K. K.; Thornton-

tallics 1999, 18, 670-678. (c) Amatore, C.; Broeker, G.; Jutand, A.;

Khalil, F. J. Am. Chem. Soc. 1997, 119, 5176-5185.

2

5

H

4

5

H

4

2

Pett, M.; Brown, J. M. Organometallics 1999, 18, 5367-5374.

(10) Krause, J.; Bonrath, W.; Porschke, K. R. Organometallics 1992,

11, 1158-1167.

(

4) Stambuli, J. P.; Incarvito, C. D.; Buhl, M.; Hartwig, J. F. J. Am.

Chem. Soc. 2004, 126, 1184-1194.

1

Publication on Web 04/22/2005

Chiral Palladium(0) trans-Stilbene Complexes

Organometallics, Vol. 24, No. 11, 2005 2731

Pd-catalyzed asymmetric phosphination¹¹and Pt-cata-

lyzed asymmetric hydrophosphination, for which the

bulky alkylphosphine Me-Duphos was a useful ligand.¹²

We previously described the well-defined catalyst pre-

cursor Pt(Me-Duphos)(trans-stilbene) and related Pt-

Scheme 1

1

3

(diphos)(trans-stilbene) compounds. Here we report a

series of analogous chiral Pd trans-stilbene complexes,

which in many cases are robust crystalline compounds

14

stable on storage. Varying the diphosphine ligand and

the metal (Ni, Pd, Pt) revealed trends in selectivity of

1

3,15

binding of one stilbene enantioface.

Oxidative addition of an aryl or vinyl halide or

sulfonate to Pd(0), the first step in popular cross-

coupling or Heck reactions, has been studied in detail.¹⁶

To investigate effects of the diphosphine ligand on this

step, we studied the oxidative addition of PhI to the

stilbene complexes and compared the rates of these

reactions to those of Pd(diphos*)(dba), generated in situ.

Structural effects of the different ligands were probed

by X-ray structure determinations of three classes of

complexes: Pd(diphos*)Cl2, Pd(diphos*)(trans-stilbene),

and Pd(diphos*)(Ph)(I), as well as some analogous Ni

compounds.

Table 1. Selected Bond Lengths (Å) and Angles

(

deg) (Average Values) in the Complexes

Pd(diphos*)Cl

2

[

1b]3‚

1a‚CH2Cl2

2(acetone)

1e

1g

diphos

Me-Duphos^aEt-Duphos^bMe-Ferro- Et-Ferro-

LANE TANE

Results and Discussion

Pd-P

Pd-Cl

2.2183(15)

2.3637(16)

2.215(3)

2.355(3)

2.2734(7) 2.2726(5)

2.3535(7) 2.3600(5)

Treatment of Pd(COD)Cl2 (COD ) cyclooctadiene)

with the chiral diphosphines shown in Scheme 1 (all are

commercially available except for Me-FerroLANE and

Me-DuXantphos) gave the air-stable complexes Pd-

P-Pd-P

87.04(5)

87.26(13)

93.81(14)

90.56(14)

175.23(10)

100.16(2) 98.799(17)

Cl-Pd-Cl 94.37(5)

P-Pd-Cl 89.26(5)

88.59(3)

85.85(2)

87.237(17)

87.098(18)

175.81(6)

172.26(2) 172.92(18)

(diphos*)Cl2 (diphos* ) (R,R)-Me-Duphos (1a), (R,R)-

a Average values. See the Supporting Information of ref 11b for

b

Et-Duphos (1b), (R,R)-i-Pr-Duphos (1c), (R,R)-Me-BPE

data. The asymmetric unit contains 1.5 Pd molecules; average

1

7

bond lengths and angles are reported.

(

1d), (S,S)-Me-FerroLANE (1e), (S,S)-Me-DuXantphos

1

8

1f), (S,S)-Et-FerroTANE (1g), (R,S)-CyPF-t-Bu (1h),

(

R,S)-PPF-t-Bu (1i), (R,S)-BoPhoz (1j)¹⁹^,²⁰), which were

characterized by NMR spectroscopy and elemental

(11) (a) Moncarz, J. R.; Laritcheva, N. F.; Glueck, D. S. J. Am. Chem.

Soc. 2002, 124, 13356-13357. (b) Moncarz, J. R.; Brunker, T. J.;

Jewett, J. C.; Orchowski, M.; Glueck, D. S.; Sommer, R. D.; Lam, K.-

C.; Incarvito, C. D.; Concolino, T. E.; Ceccarelli, C.; Zakharov, L. N.;

Rheingold, A. L. Organometallics 2003, 22, 3205-3221.

analyses.

Little is known about the Pd coordination chemistry

of some of these ligands;²¹thus, the PdCl2 complexes of

Et-Duphos, Et-FerroTANE, and Me-FerroLANE were

further characterized by X-ray crystallography (Table

(

12) Kovacik, I.; Wicht, D. K.; Grewal, N. S.; Glueck, D. S.; Incarvito,

C. D.; Guzei, I. A.; Rheingold, A. L. Organometallics 2000, 19, 950-

53.

13) Wicht, D. K.; Zhuravel, M. A.; Gregush, R. V.; Glueck, D. S.;

Guzei, I. A.; Liable-Sands, L. M.; Rheingold, A. L. Organometallics

998, 17, 1412-1419.

14) For Pd(diphos)(stilbene)H

9

1

and the Supporting Information). Apart from the

(

expected larger bite angles for the ferrocene-based

ligands, the structures are quite similar, with the Pd-P

bond distances slightly greater for 1e,g.

1

(

2

complexes as proposed intermediates

in hydrogenation of diphenylacetylene, see: Dunne, J. P.; Aiken, S.;

Duckett, S. B.; Konya, D.; Almeida Le n˜ ero, K. Q.; Drent, E. J. Am.

Chem. Soc. 2004, 126, 16708-16709.

The DuXantphos complex 1f displayed unusual NMR

behavior. At room temperature in CD2Cl2 or CDCl3, the

(

15) Cucciolito, M. E.; Flores, G.; Vitagliano, A. Organometallics

1

31

2

004, 23, 15-17.

16) (a) Roy, A. H.; Hartwig, J. F. Organometallics 2004, 23, 194-

02. (b) Amatore, C.; Bensalem, S.; Ghalem, S.; Jutand, A.; Medjour,

H NMR spectrum contained broad peaks, and the

P

(

NMR spectrum (CD2Cl2) included a sharp low-intensity

singlet at δ 31.8 (<5%) plus two broad signals at δ 48.8

and 37.3. When the temperature was lowered to -20

2

Y. Eur. J. Org. Chem. 2004, 366-371. (c) Lewis, A. K. d. K.; Caddick,

S.; Cloke, F. G. N.; Billingham, N. C.; Hitchcock, P. B.; Leonard, J. J.

Am. Chem. Soc. 2003, 125, 10066-10073. (d) Roy, A. H.; Hartwig, J.

F. J. Am. Chem. Soc. 2003, 125, 8704-8705. (e) Jutand, A.; Negri, S.

Organometallics 2003, 22, 4229-4237. (f) Alcazar-Roman, L. M.;

Hartwig, J. F. Organometallics 2002, 21, 491-502. (g) Amatore, C.;

Carr e´ , E.; Jutand, A.; Medjour, Y. Organometallics 2002, 21, 4540-

°

C, these broad signals sharpened to two doublets (J )

1

9 Hz) at δ 49.2 and 36.6. At this temperature, the H

NMR spectrum contained signals for six inequivalent

methyl groups.

4

545. (h) Alcazar-Roman, L. M.; Hartwig, J. F. J. Am. Chem. Soc. 2001,

1

23, 12905-12906. (i) Alami, M.; Amatore, C.; Bensalem, S.; Choukchou-

These observations are consistent with the existence

at room temperature) of a small amount of the trans

Brahim, A.; Jutand, A. Eur. J. Inorg. Chem. 2001, 2675-2681. (j)

Alcazar-Roman, L. M.; Hartwig, J. F.; Rheingold, A. L.; Liable-Sands,

L. M.; Guzei, I. A. J. Am. Chem. Soc. 2000, 122, 4618-4630. (k)

Amatore, C.; Fuxa, A.; Jutand, A. Chem. Eur. J. 2000, 6, 1474-1482.

(

(19) Boaz, N. W.; Debenham, S. D.; Mackenzie, E. B.; Large, S. E.

Org. Lett. 2002, 4, 2421-2424.

(

17) Burk, M. J.; Gross, M. F. Tetrahedron Lett. 1994, 35, 9363-

366.

18) (a) Dierkes, P.; Ramdeehul, S.; Barloy, L.; De Cian, A.; Fischer,

9

(20) The dichloride complexes 1a,h were reported previously. For

1a, see ref 11b and: (a) Drago, D.; Pregosin, P. S. Organometallics

2002, 21, 1208-1215. (b) Malais e´ , G.; Barloy, L.; Osborn, J. A.;

Kyritsakas, N. C. R. Chim. 2002, 5, 289-296. For 1h, see ref 16d.

(21) Brunker, T. J.; Moncarz, J. R.; Glueck, D. S.; Golen, J. A.;

Rheingold, A. L. Organometallics 2004, 23, 2228-2230.

(

J.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Osborn, J. A. Angew.

Chem., Int. Ed. 1998, 37, 3116-3118. (b) Malaise, G.; Ramdeehul, S.;

Osborn, J. A.; Barloy, L.; Kyritsakas, N.; Graff, R. Eur. J. Inorg. Chem.

2

004, 3987-4001.

2732 Organometallics, Vol. 24, No. 11, 2005

Brunker et al.

Chart 1. Trans and Cis Isomers of

as precursors for catalytic asymmetric phosphination (to

be described separately), it is more convenient to use

excess stilbene in the synthesis of 2a-c. A slight excess

of trans-stilbene (ca. 1.1 equiv) was used to prepare

complexes of the other diphosphines. In all cases,

analogous toluene-insoluble material was observed;

yields and ease of purification depended on the ligand.

Stilbene complexes 2a-j were isolated as greenish

yellow, orange, or brown crystalline solids. In most

cases, they were stored in a freezer under nitrogen as a

precaution; under these conditions they were stable for

months. For comparison to other Pd alkene complexes,

we also investigated their stability in solution and in

the solid state at room temperature, which depended

on the diphosphine ligand. Freshly recrystallized 2a, a

bright canary yellow solid, gradually changed color to

greenish yellow and then gray yellow on standing in the

solid state under nitrogen. When a pentane solution of

this material was filtered through Celite to remove a

gray precipitate (presumably Pd metal) and then con-

centrated, 2a could be recovered as a yellow solid.

Heating a solution of 2a in toluene to 100 °C overnight

caused some decomposition to Pd metal, but a ³¹P NMR

spectrum of the yellow solution showed that 2a sur-

vived. The Et-FerroTANE complex 2g was stable as a

solid and decomposed slowly in solution over several

days; the Me-FerroLANE complex 2e was formed in

higher yield with less byproduct and was more stable

in solution as well. The Me-BPE complex 2d was the

most sensitive in this Pd phospholane series, decompos-

ing slowly even on storage as a solid in the glovebox

freezer (-25 °C; yellow crystals formed a brown solid);

in C6D6 solution some decomposition was observed in

just a few hours.

2

Pd(Me-DuXantphos)Cl (1f)

_S_c_h_e_m_e₂a

a

[

Pd] ) Pd(diphos*).

isomer and a fluxional major cis isomer. The C2-

symmetric cis isomer, which requires a planar xanthane

ring system (Chart 1), would have equivalent P nuclei

and three pairs of equivalent Me groups, but molecular

modeling suggests that this conformation induces greater

steric repulsions than others in which the ring is

puckered. With such an envelope conformation in the

C2-symmetric cis isomer, the P nuclei and all six Me

groups are inequivalent, as observed at low tempera-

ture. These NMR observations are consistent with the

NMR and X-ray crystallographic results of Osborn et

al. on a Pd cyclohexenyl cation with a closely related

NaBH(OMe)3 reduction of Pd(Me-DuXantphos)Cl2 in

the presence of stilbene led to formation of free Me-

DuXantphos as well as a material believed to be Pd-

(

Me-DuXantphos)(trans-stilbene) (2f). Like the other

Me-DuXantphos complexes described here, 2f showed

broad room-temperature H and P NMR spectra. Low-

temperature H NMR spectra revealed resonances

1

8

ligand. The fluxional process may involve inter-

conversion of different ligand ring conformations via

the C2-symmetric isomer; related observations in a

variety of Pd-Xantphos complexes have been described

1

31

1

characteristic of coordinated stilbene (see the Experi-

mental Section), but 2f could not be isolated in pure

form to enable study of its fluxionality in solution.

The Josiphos complexes 2h,i were robust both as

solids and in solution, but the BoPhoz derivative 2j

decomposed at room temperature even in the solid state,

so that we could not obtain correct elemental analyses

for this complex. However, it could be stored as a solid

at -30 °C under nitrogen without decomposition.

The nickel complex Ni(Me-Duphos)(trans-stilbene)

1

8b,22

recently.

As in analogous Pt chemistry,¹³reduction of dichloride

precursors 1a-j with an excess (typically 3 equiv) of

NaBH(OMe)3 in THF in the presence of trans-stilbene

gave the title stilbene complexes Pd(diphos*)(trans-

1

1a

stilbene) 2a-j (Scheme 2).

After the THF was re-

moved in vacuo, extraction with toluene removed uni-

dentified brown material, and 2a-j were purified by

recrystallization. For the Duphos complexes 2a-c, using

an excess (2-3 equiv) of stilbene reduced the amount

of brown impurity and simplified the workup, but it was

difficult to separate the excess stilbene from the Pd

complexes. With 1 equiv of stilbene, more brown mate-

rial was formed; yields were reduced and purification

was more difficult, but Pd complexes free of excess

stilbene could be obtained. Because small amounts of

free stilbene did not affect oxidative addition of PhI to

the stilbene complexes (see below) or their performance

(

Ni-2a), which is highly air-sensitive in solution but

23

stable as a solid, was prepared similarly. Although

treatment of Ni(COD)2 (COD ) 1,5-cyclooctadiene) with

trans-stilbene in the presence of triarylphosphines gave

24

Ni(PAr3)2(trans-stilbene), a similar reaction of Ni-

(

COD)2 with Me-Duphos and stilbene gave instead Ni-

Me-Duphos)(COD) (4), along with a small amount of

(23) For other Ni(diphos)(trans-stilbene) complexes, see: (a) Casal-

nuovo, A. L.; RajanBabu, T. V.; Ayers, T. A.; Warren, T. H. J. Am.

Chem. Soc. 1994, 116, 9869-9882. (b) Hofmann, P.; Perez-Moya, L.

A.; Krause, M. E.; Kumberger, O.; Mueller, G. Z. Naturforsch., B 1990,

45, 897-908. (c) Sillett, G.; Ricard, L.; Patois, C.; Mathey, F. J. Am.

Chem. Soc. 1992, 114, 9453-9457.

(

22) Zuideveld, M. A.; Swennenhuis, B. H. G.; Boele, M. D. K.; Guari,

Y.; van Strijdonck, G. P. F.; Reek, J. N. H.; Kamer, P. C. J.; Goubitz,

K.; Fraanje, J.; Lutz, M.; Spek, A. L.; van Leeuwen, P. W. N. M. Dalton

(24) Ittel, S. D.; Ibers, J. A. J. Organomet. Chem. 1974, 74, 121-

134.

2

002, 2308-2317.

Chiral Palladium(0) trans-Stilbene Complexes

Organometallics, Vol. 24, No. 11, 2005 2733

Table 2. Selected NMR Data for M(diphos*)(trans-stilbene) Complexes^a

1

b

δ(¹³C)^c

compd

diphos

diastereomer ratio

5.6:1

δ(³¹P)

57.6

0.8

51.5

6.4

44.7

7.6

55.8

5.3

36.2

2.5

44.1

7.7

76.5, 20.3

2.9, 18.6

δ( H)

2

a

b

c

d

e

g

h

i

Me-Duphos

5.50 (d, J ) 2)

5.25 (d, J ) 2)

5.46 (d, J ) 2)

5.24 (d, J ) 2)

5.34 (d, J ) 2)

5.18

60.6 (t, J ) 10)

5

64.2 (m)

Et-Duphos

i-Pr-Duphos

Me-BPE

7.8:1

38:1

2.5:1

6.4:1

10.3:1

40:1

25:1

2:1

60.2 (t, J ) 10)

4

64.0

62.9 (t, J ) 11)

4

d

5.44 (d, J ) 2)

5.40 (d, J ) 2)

5.02 (m)

62.6 (t, J ) 11)

60.7 (t, J ) 10)

4

Me-FerroLANE

Et-FerroTANE

CyPF-t-Bu

PPF-t-Bu

63.6 (m)

d

3

5.00 (m)

5.33

64.8 (t, J ) 10)

3

5.30

d

e

f

4.78 (br), 4.68 (m)

d

4.97, 4.33

66.3 (d, J ) 28), 63.7 (dd, J ) 27, 5)

8

d

e

f

77.5, 9.6

d

69.9 (dd, J ) 23, 5), 68.6 (d, J ) 28)

d

e

f

71.9 (m), 66.5 (m)^g

d

j

BoPhoz

89.8, 8.6

5.33, 5.19

5.86 (br), 5.52 (br)

4.67

90.2, 8.1

Ni-2a

Me-Duphos

55:1

3:1

68.9

0.9

71.4

6.3

52.5 (t, J ) 9)

d

6

4.32

Pt-2a^h

4.64 (m)

4.45 (m)

50.3 (t, J ) 16)

53.4 (t, J ) 16)

6

a

b

Solvent: C6D6. Chemical shifts are given in ppm and coupling constants in Hz. Data for the major diastereomer is given first. Stilbene

CH. ^cStilbene CH. ^dNot observed. For the unsymmetrical complexes 2h-j, JPP values in Hz for the major and minor diastereomers,

respectively, are as follows: for 2h, 5, not observed; for 2i, 14, not observed; for 2j, 23, 21. For 2h-j, JHH ) 10 Hz. JPH values (Hz) are

e

f

as follows: for 2h, (δ 4.68) 4.5, 5.0, (δ 4.78) 5.0, 4.5; for 2i, (δ 4.33) 4.5, 8.0; (δ 4.97) 4.7, 6.3. for 2j, JPH appeared to be similar in magnitude,

but the broadness of the peaks precluded precise simulations. For 2h-j, the similar magnitudes of the two JPH couplings prevented us

1

g

from making assignments of the stilbene CH H NMR signals to specific protons. In toluene-d8, these peaks were better resolved and

h

showed doublet couplings of 20 and 27 Hz, respectively. Reference 13.

Scheme 3^a

28

stilbenes ArCHdCHAr′, where JHH ≈ 16 Hz, in

complexes 2h-j JHH is reduced to ∼10 Hz, consistent

with a change in hybridization of the stilbene carbons

on binding to Pd.²⁹

The ratio of diastereomers for the trans-stilbene

complexes depended on the ligand, increasing signifi-

cantly in the Duphos series a-c as the ligand substit-

uents increase in size. As the metal is varied in the

series M(Me-Duphos)(trans-stilbene), selectivity of stil-

bene binding decreased down the group (Ni (55:1) > Pd

a

[

Ni] ) Ni(Me-Duphos).

(5.6:1) > Pt (3:1)). Nickel’s position as the most selective

Ni(Me-Duphos)2 (5).²⁵Complexes 4 and 5 were prepared

directly from Ni(COD)2 and 1 or 2 equiv of Me-Duphos

Scheme 3).

is readily rationalized in terms of its smaller size, which

magnifies Duphos-stilbene steric interactions, but the

difference between the Pd and Pt complexes, where the

metals are presumably similar in size, is less easy to

explain.

The crystal structures of the palladium stilbene

complexes 2c,g,h, the nickel stilbene complex Ni-2a,

and the nickel cyclooctadiene complex 4 are shown in

Figures 1-5; see Tables 3 and 4 for crystallographic

details and selected bond lengths and angles.

(

Characteristic NMR data for the trans-stilbene com-

plexes are summarized in Table 2. No exchange of free

and bound stilbene was observed on the NMR time

scale. In the Pd complexes, the coordinated trans-

stilbene gave rise to H NMR signals around 5 ppm and

C NMR alkene resonances near 60 ppm. Interestingly,

in Ni-2a and Pt-2a, these H peaks appeared at lower

chemical shift than in the Pd analogue 2a, near 4.5 ppm,

as did the C signals, near 50 ppm.

Because the Josiphos and BoPhoz ligands in 2h-j are

not C2 symmetric, the stilbene CH protons and carbons

are inequivalent. Selective P-decoupling experiments

1

3

1

As mentioned above, palladium alkene complexes

have been less investigated than those of nickel and

platinum. Previous work suggested that the affinity of

1

3

Pd for alkene ligands is weaker than that of the other

3

1

30,31

metals.

Structural characterization of Ni-2a, 2c, and

1

26

and simulation of the H NMR spectra with gNMR

enabled assignment of the JHH and JPH coupling con-

Pt-2a permits comparison of metal-stilbene binding in

stants for coordinated stilbene (see Table 2). In com-

parison to trans-stilbene itself, or unsymmetrical

(

27) Mucci, A.; Parenti, F.; Schenetti, L. Eur. J. Org. Chem. 2002,

2

7

938-940.

(

28) (a) Yao, Q.; Kinney, E. P.; Yang, Z. J. Org. Chem. 2003, 68,

7

528-7531. (b) Littke, A. F.; Fu, G. C. J. Org. Chem. 1999, 64, 10-

(

25) For other Ni(diphos)(COD) complexes, see: (a) Spielvogel, D.

11.

J.; Davis, W. M.; Buchwald, S. L. Organometallics 2002, 21, 3833-

(29) (a) Cramer, R.; Kline, J. B.; Roberts, J. D. J. Am. Chem. Soc.

3

836. (b) Pawlas, J.; Nakao, Y.; Kawatsura, M.; Hartwig, J. F. J. Am.

1969, 91, 2519-2524. (b) Cook, C. D.; Wan, K. Y. J. Am. Chem. Soc.

1970, 92, 2595-2597.

Chem. Soc. 2002, 124, 3669-3679. (c) van Soolingen, J.; Brandsma,

L.; Kruse, C. G. Eur. Pat. Appl. 613719, 1993.

(30) Bennett, M. A.; Chiraratvatana, C.; Robertson, G. B.; Toopta-

kong, U. Organometallics 1988, 7, 1403-1409.

(31) Tolman, C. A.; Seidel, W. C.; Gerlach, D. H. J. Am. Chem. Soc.

1972, 94, 2669-2676.

(

26) gNMR (Budzelaar, P. gNMR v3.6.5; Cherwell Scientific, 1992-

1

996) is commercial software for the simulation and analysis of NMR

spectra.

2734 Organometallics, Vol. 24, No. 11, 2005

Brunker et al.

Figure 3. ORTEP diagram of Pd((R,S)-CyPF-t-Bu)(trans-

stilbene) (2h).

Figure 1. ORTEP diagram of Pd((R,R)-i-Pr-Duphos)-

trans-stilbene) (2c).

(

Figure 4. ORTEP diagram of Ni((R,R)-Me-Duphos)(trans-

stilbene) (Ni-2a).

Figure 2. ORTEP diagram of Pd((S,S)-Et-FerroTANE)-

trans-stilbene) (2g).

(

the series. As expected, the complex of the smaller Ni

atom featured the shortest M-C and M-P bonds.

Weaker Pd-C interactions, with reduced back-bonding

in comparison to the other metals, would be expected

to result in longer Pd-C and CdC (stilbene) distances,

but the differences observed are small or not significant.

We have not attempted further comparative structural

32

analysis of the metal-stilbene bonding, because steric

effects of the larger i-Pr-Duphos ligand in 2c may

obscure electronic effects of the different metals.

Comparison of structures with the same metal sug-

gests that varying the diphosphine ligand has little

effect on the metal-stilbene interaction. For the Pd

complexes 2c,g,h, although the FerroTANE and CyPF-

t-Bu bite angles are considerably larger than that of

i-Pr-Duphos (106.673(18), 100.29(8), and 89.01(2)°, re-

spectively), the structures are otherwise very similar.

Likewise, the complex Ni(dtbpm)(trans-stilbene) (dtbpm

Figure 5. ORTEP diagram of Ni((R,R)-Me-Duphos)(COD)

(4).

)

(t-Bu)2PCH2P(t-Bu)2) features an unusually small bite

angle (79.6(1)°) in comparison to that in Ni-2a (91.84-

(

3)°).²The shorter Ni-C and longer CdC (stilbene)

3b

(32) Ittel, S. D.; Ibers, J. A. Adv. Organomet. Chem. 1976, 14, 33-

6

1.

distances in Ni-2a might be attributed to a stronger

Chiral Palladium(0) trans-Stilbene Complexes

Organometallics, Vol. 24, No. 11, 2005 2735

, 3i‚CH Cl , and 4

Table 3. Crystallographic Data for Complexes 2c,g,h, Ni-2a, 3a, 3g‚0.33C

7

H

8

2

c

2g

2h

Ni-2a

3a

3g‚0.33C7H8

C32.33H43.67Fe- C39H47Cl2Fe- C26H40NiP2

IP2Pd IP2Pd

3i‚CH2Cl2

4

formula

C40H56P2Pd C38H48Fe-

P2Pd

705.19

P212121

10.8583(6)

15.3242(9)

C46H64Fe-

P2Pd

841.16

P212121

14.4666(12) 11.9233(19) 9.8739(6)

18.2168(15) 12.158(2)

C32H40NiP2

C30H39I-

P2Pd

694.85

P21

fw

728.95

P212121

11.5878(6)

15.2320(8)

545.29

P212121

783.43

937.76

473.23

P21212

17.4446(8)

18.0140(9)

7.8476(4)

90

2466.1(2)

4

1.275

0.927

space group

a, Å

P43

P21

17.7091(6)

30.6787(19)

9.612(3)

15.196(5)

13.524(5)

92.40(3)

1973.7(11)

2

b, Å

16.9699(10)

10.0976(6)

116.8340(10) 90

1509.75(16)

2

1.529

1.759

173(2)

0.0199

0.0439

c, Å

22.2132(13) 19.4887(10) 18.3127(16) 20.517(4)

â, deg

90

3

V, Å

Z

3696.2(4)

4

1.267

0.614

100(2)

0.0330

0.0650

3439.9(3)

4

1.408

1.062

150(2)

0.0217

0.0526

4826.0(7)

4

1.158

0.766

203(2)

0.0669

0.1599

2974.2(9)

4

1.218

0.778

213(2)

0.0352

0.0837

9621.2(8)

12

1.623

2.095

100(2)

0.0438

0.0876

3

D(calcd), g/cm

1.578

1.848

-

1

µ(MoKR), mm

temp, K_a

252(2)

0.0349

0.0873

213(2)

0.0397

0.0816

R(F), %

2

a

R(wF ), %

a

2

2 2

2 2 1/2

2

Quantity minimized ) R(wF ) ) ∑[w(Fo - Fc ) ]/∑[(wFo ) ] ; R ) ∑∆/∑(Fo), ∆ ) |(Fo - Fc)|, w ) 1/[σ (Fo ) + (aP) + bP], P ) [2Fc

Max(Fo,0)]/3.

+

Table 4. Selected Bond Lengths (Å) and Angles (deg) in the Complexes M(diphos*)(trans-stilbene)

Ni-2a

2c

Pt-2a

Me-Duphos^a

2g

2h

Ni-dtbpm

dtbpm^b

diphos

Me-Duphos

2.1240(6)

i-Pr-Duphos

Et-FerroTANE

CyPF-t-Bu

M-P

2.2787(7)

2.2859(7)

2.136(3)

2.134(3)

1.419(4)

2.235(4)

2.240(3)

2.102(12)

2.113(12)

1.436(18)

2.2927(5)

2.3012(5)

2.1498(17)

2.1599(19)

1.417(3)

2.314(2)

2.344(2)

2.125(8)

2.156(8)

1.430(13)

2.222(1)

2.218(1)

1.982(4)

1.979(4)

1.430(7)

2

.1267(6)

M-C

1.965(2)

1

.975(2)

C-C

1.417(3)

P-M-P

C-M-C

P-M-C

91.84(3)

42.16(9)

113.75(7)

89.01(2)

88.49(13)

39.8(5)

115.5(4)

116.2(4)

155.3(4)

155.9(4)

106.673(18)

38.39(7)

107.56(5)

107.45(5)

145.72(5)

145.87(5)

100.29(8)

39.0(3)

107.0(3)

113.8(2)

145.5(2)

152.7(3)

79.6(1)

38.83(11)

117.09(8)

114.75(8)

153.37(8)

155.79(8)

42.3(2)

118.7(2)

120.2(1)

159.2(10)

161.0(2)

1

12.27(7)

54.14(7)

55.88(7)

(

P-M-P)-(C-M-C)^c

4.6

5.0

3.9

4.1

7.2

14.4

a

Reference 13. ^bReference 23b. ^cDihedral angle between these planes.

Scheme 4^a

Table 5. Selected Bond Distances (Å) and Angles

(

deg) for the Complexes

Ni((R,R)-Me-Duphos)(COD) (4) and

a

Ni(S-BINAP)(COD)

Ni((R,R)-Me-Duphos)(COD) Ni(S-BINAP)(COD)

Ni-C (av)

Ni-P (av)

C-C (av)

2.0987(3)

2.1529(7)

1.365(5)

2.110(10)

2.174(3)

1.394(13)

P-Ni-P

C-Ni-C (av)

90.48(3)

37.95(14)

97.37(10)

38.6(4)

a

Reference 25a.

a

[

2 3 2

Pd] ) Pd(Diphos*); L ) (PPh ) , TMEDA.

Ni-C bond with greater back-bonding, but these obser-

vations, as well as the longer Ni-P bonds in the dtbpm

complex, could also result from greater steric crowding.

Details of a similar comparison of Ni(Me-Duphos)-

Duphos (ca. 6%) and i-Pr-Duphos (ca. 26%) complexes.³³

In contrast, no diiodide impurities were observed for the

faster (minutes) oxidative additions of BPE, Ferro-

LANE, and FerroTANE complexes 2d,e,g. Treatment

of the impure Me-DuXantphos complex 2f with PhI also

led to oxidative addition within minutes to yield trans-

Pd(Me-DuXantphos)(Ph)(I) (3f; see below). Oxidative

addition to the Josiphos and BoPhoz complexes 2h-j

also proceeded quickly.

In summary, the large bite angle ligands (ferrocene-

based, or DuXantphos) led to fast oxidative addition.

Results in the Duphos/BPE series showed that reduced

steric bulk also promoted oxidative addition. Further

analysis of these structural trends would require de-

_C_O_D₎₍₄₎_w_i_t_h_t_h_e_a_n_a_l_o_g_o_u_s_B_I_N_A_P_c_o_m_p_l_e_x2 are

5a

(

shown in Table 5. As expected, the less sterically

demanding, better donor ligand Me-Duphos resulted in

shorter Ni-P bonds, and the BINAP bite angle was

larger than that of Me-Duphos. However, Ni-COD

bonding does not differ significantly in these structures.

Oxidative addition of PhI to the stilbene complexes

was studied in NMR tube scale experiments in toluene

(

Scheme 4 and Table 6). For the Duphos complexes,

oxidative addition occurred in minutes to hours, more

quickly for the smaller ligands, in the order Me-Duphos

>

Et-Duphos > i-Pr-Duphos. A trace of the complex Pd-

(

33) These diiodide complexes were identified by ³¹P NMR spectros-

11b 31

(

Me-Duphos)I2 was observed as a byproduct from 2a,

copy in comparison to the well-characterized Pd(Me-Duphos)I

2

.

P

with increasing amounts of impurities assumed to be

the analogous diiodide complexes seen for the larger Et-

2

NMR chemical shifts (toluene): for Pd(Et-Duphos)I , δ 84.5; for Pd(i-

Pr-Duphos)I , δ 81.7.

2

2736 Organometallics, Vol. 24, No. 11, 2005

Brunker et al.

Table 6. Oxidative Addition of PhI to

Chart 2. Josiphos Complexes 3h,i and BoPhoz

M(diphos*)(trans-stilbene) Complexes and to

_C_o_m_p_l_e_x₃_ja

a

2

Mixtures of Pd(dba) and diphos*

approx reacn

b,c

compd

Diphos*

time

byproduct

2

a

Me-Duphos

<25 min

NR (70 h)

[Pd]I2 (trace)

c

2

a-dba

2

b

Et-Duphos

i-Pr-Duphos

Me-BPE

3 h

[Pd]I2 (6%)

2

b-dba

NR (70 h)

2

c

9 h

(70 h)

[Pd]I2 (26%)

d

c-dba

[Pd]I2

a

The complexes 3h,i were formed as single diastereomers,

2

d

15 min

NR (28 h)

e

but complex 3j was an 8:1 mixture.

d-dba

2

e

Me-FerroLANE

DuXantphos

Et-FerroTANE

CyPF-t-Bu

PPF-t-Bu

5 min

37% (74 h)

in toluene to yield trans-Pd(Me-DuXantphos)(Ph)(I) (see

below), and Pd(dba)2/BoPhoz underwent PhI oxidative

addition overnight. When Josiphos/Pd(dba)2 mixtures

were treated with PhI, no reaction occurred with the

CyPF-t-Bu ligand, and slow oxidative addition occurred

on heating for PPF-t-Bu. Slow oxidative addition of aryl

halides to Pd(diphos)(dba) complexes has been observed

previously and rationalized by the reluctance of the dba

ligand to dissociate from Pd to afford the reactive

e-dba

2

f

5 min

2 h

f-dba

2

g

5 min

56% (51 h)

g-dba

2

h

<60 min _f

2

h-dba

NR (24 h)

2

i

<45 min

72 h, 50 °C

i-dba

3b,34

intermediate Pd(diphos).

2

j

BoPhoz

<30 min

24 h

As stated by a reviewer, “oxidative addition of Pd(0)

complexes to PhI is generally fast and kinetically

irrelevant in most mechanistic cycles of practical rel-

evance.” However, these results show that the rate of

PhI oxidative addition depends strongly on the precur-

sor, at least under the mild (room-temperature) condi-

tions studied here. For several chiral diphosphines,

oxidative addition occurred slowly or not at all when

Pd(dba)2/diphos mixtures were used. Since this reaction

proceeded more quickly with stilbene complexes 2, they

may be preferable catalyst precursors in some cases.

The oxidative addition products Pd(diphos*)(Ph)(I)

j-dba

Ni-2a

Pt-2a

Me-Duphos

100 min

g

[Pt]I2 (major

product)

a

Conditions: room temperature, ∼1.5 equiv of PhI, toluene.

3

1

b

Reactions were monitored by P NMR spectroscopy. Time for

complete conversion to the product [M](Ph)(I) and byproducts,

[

M]I2. In cases where conversion was not complete, the reaction

c

time and percent conversion are reported. NR ) no reaction.

d

e

f

Yield was not determined. No byproducts were observed. No

reaction after 24 h at room temperature or after 48 h at 60 °C.

g

No reaction at room temperature; heating to 60 °C gave a small

amount of Pt-3a and Pt(Me-Duphos)I2 as the major product.

(

3a-j) were prepared independently by ligand substitu-

35

36 37

tion reactions of PdL2(Ph)(I) (L2 ) TMEDA, (PPh3)2 ).

For Me-Duphos, synthesis via the TMEDA complex,

even at low temperature in the dark, led to the forma-

tion of traces of Pd(Me-Duphos)2 and Pd(Me-Duphos)-

tailed knowledge of the mechanism of oxidative addi-

tion, which we have investigated in only one case. Added

trans-stilbene clearly slowed the rate of oxidative ad-

dition of PhI to Pd(Me-Duphos)(trans-stilbene) (2a).

Reaction was complete in <1 h for pure 2a but required

h when 5 equiv of stilbene was added and >24 h with

0 equiv. These results are consistent with an important

contribution from a dissociative pathway, as reported

for PhI oxidative addition to Pd(diphos)(dba).³^aSimi-

larly, we previously observed that added trans-stilbene

slowed conversion of one diastereomer of Pt(Tol-Binap)-

11b

I2; thus, the alternative route was preferred. For the

non-C2-symmetric Josiphos and BoPhoz complexes, two

regioisomers could be formed (Chart 2). Only one was

observed for Josiphos complexes 3h,i. X-ray crystal-

lographic structure determinations (see below) showed

that the Ph group was trans to the P(t-Bu)2 ligand,

5

1

consistent with Hartwig’s observations on related

16a,d

Josiphos phenyl bromide complexes.

For the BoPhoz

(

trans-stilbene) into the other, which suggested isomer-

compound 3j, both diastereomers were observed, in a

:1 ratio. Although 3j appeared to be relatively stable

ization occurred by a dissociative mechanism involving

loss of stilbene and binding of the other enantioface.¹³

For comparison, mixtures of Pd(dba)2 and a chiral

diphosphine were prepared. These solutions presumably

contain Pd(diphos*)(dba), consistent with their ³¹P NMR

spectra (see Table 9 in the Experimental Section), but

they were not characterized further. Under comparable

conditions (toluene, room temperature, ca. 1.5 equiv of

PhI), their reactions with PhI were much slower than

those of the stilbene complexes. Pd(dba)2/Duphos mix-

tures with PhI led either to no reaction (Me-Duphos,

Et-Duphos) or to the formation of a small amount of Pd-

8

in solution, it underwent partial decomposition on

attempted isolation; for details, see the Experimental

Section.

38

As observed for dichloride 1f, the Me-DuXantphos

complex 3f displayed broad NMR spectra in CD2Cl2 at

(34) Reid, S. M.; Mague, J. T.; Fink, M. J. J. Organomet. Chem. 2000,

6

16, 10-18.

(

35) (a) de Graaf, W.; van Wegen, J.; Boersma, J.; Spek, A. L.; van

Koten, G. Recl. Trav. Chim. Pays-Bas 1989, 108, 275-277. (b) Markies,

B. A.; Canty, A. J.; de Graaf, W.; Boersma, J.; Janssen, M. D.;

Hogerheide, M. P.; Smeets, W. J. J.; Spek, A. L.; van Koten, G. J.

Organomet. Chem. 1994, 482, 191-199.

(

i-Pr-Duphos)I2. The FerroLANE and FerroTANE dba

(36) (a) Fitton, P.; Rick, E. A. J. Organomet. Chem. 1971, 28, 287-

91. (b) Fitton, P.; Johnson, M. P.; McKeon, J. E. J. Chem. Soc., Chem.

2

complexes reacted slowly with PhI to give the oxida-

tive addition products. In contrast, a mixture of

Me-DuXantphos and Pd(dba)2 reacted rapidly with PhI

Commun. 1968, 6-7.

37) We reported FerroTANE complex 3g previously, and the Me-

Duphos complex 3a was described in both ref 11a and ref 20a.

21

(

Chiral Palladium(0) trans-Stilbene Complexes

Organometallics, Vol. 24, No. 11, 2005 2737

Scheme 5^a

Scheme 6^a

a

[

Ni] ) Ni(Me-Duphos).

Scheme 7^a

a

[

M] ) M(Me-Duphos).

Scheme 8^a

a

[

Pd] ) Pd(Me-DuXantphos).

room temperature, characteristic of a fluxional process.

Low-temperature ³¹P and H NMR spectroscopy were

consistent with the existence of two isomers of this

complex, the C1-symmetric cis-3f and C2-symmetric

trans-3f, formulated as a cation with a Pd-O interaction

by analogy to related Pd-Xantphos complexes (Scheme

1

a

[

Pt] ) Pt(Me-Duphos).

position in solution. In any case, treatment of Ni(PPh3)2-

Ph)(I) with Me-Duphos also gave impure Ni-3a. In

contrast, reaction of the well-behaved Ni(PPh3)2(Ph)-

(

2

5

). Once purified, this material did not dissolve in

toluene. These isomers are different from that observed

in toluene as a result of oxidative addition of PhI to Pd-

40

(

Cl) with Me-Duphos gave Ni(Me-Duphos)(Ph)(Cl),

which was isolated in good yield and characterized

crystallographically (see the Experimental Section and

the Supporting Information).

In separate experiments, oxidative addition of PhI to

the Pd complex 2a was somewhat faster than that to

Ni-2a. In a competition experiment, a mixture of 2a and

Ni-2a was treated with PhI (Scheme 7). Oxidative

addition of PhI to the Pd complex occurred more quickly;

it was complete before formation of Ni-3a, consistent

with the individual rates.

In contrast, the Pt analogue Pt(Me-Duphos)(trans-

stilbene) (Pt-2a) did not react with PhI at room tem-

perature. When the temperature was raised to 60 °C,

some Pt(Me-Duphos)(Ph)(I) (Pt-3a) formed; further

(

dba)2/Me-DuXantphos or to impure Pd(Me-DuXant-

phos)(stilbene). It showed a characteristic AB pattern

in the P NMR spectrum, assigned to neutral trans-3f.

When the toluene was removed and this material was

dissolved in CD2Cl2, it displayed a P NMR spectrum

identical with that of the isolated material, cationic

trans-3f. This is consistent with ionization of the iodide

being favored in the more polar solvent.

3

1

3

1

Oxidative addition of PhI to Ni(Me-Duphos)(trans-

stilbene) (Ni-2a) quickly gave Ni(Me-Duphos)(Ph)(I)

(Ni-3a) (Scheme 6), although this complex could not be

isolated in pure form (see the Experimental Section).

It could also be generated as the major product by

treatment of Ni(COD)2 with Me-Duphos and PhI. In

another approach, oxidative addition of PhI to Ni(PPh3)4

gave Ni(PPh3)2(Ph)(I). This complex has been reported

several times in the literature, but without details of

heating gave large amounts of Pt(Me-Duphos)I (pre-

pared independently; see the Experimental Section) as

2

the major product (Scheme 8). Complex Pt-3a was also

prepared either by treatment of Pt(COD)(Ph)(I)⁴¹with

39

its characterization. Its NMR spectra (see the Experi-

mental Section) suggested the presence of paramagnetic

materials, as commonly observed for Ni(II), and decom-

(39) (a) Schoenberg, A.; Heck, R. F. J. Am. Chem. Soc. 1974, 96,

7

1

761-7764. (b) Fauvarque, J. F.; Jutand, A. J. Organomet. Chem.

979, 177, 273-281. (c) Garrou, P. E.; Heck, R. F. J. Am. Chem. Soc.

976, 98, 4115-4127. (d) Giannoccaro, P.; Pannacciulli, E. J. Orga-

(

38) The instability of 3j may be due to the seven-membered Pd-

nomet. Chem. 1987, 319, 119-127. (e) Reference 49 is often cited for

the preparation of this complex, but it describes only the related

chemistry of aryl chlorides and bromides.

(

BoPhoz) ring, as observed in analogous complexes with related

chelates. (a) Pd(Diop)(Ph)(I) exists in a concentration-dependent equi-

librium with chelate ring-opened oligomeric species (de Graaf, W.;

Boersma, J.; van Koten, G.; Elsevier: C. J. J. Organomet. Chem. 1989,

(40) Zeller, A.; Herdtweck, E.; Strassner, T. Eur. J. Inorg. Chem.

2003, 1802-1806.

(41) Clark, H. C.; Manzer, L. E. J. Organomet. Chem. 1973, 59, 411-

428.

3

78, 115-124; see also reference 26 therein). (b) Pd(MeO-Biphep)(Ph)-

3b

(

2

I) decomposes quickly to yield Pd(MeO-Biphep)I .

2738 Organometallics, Vol. 24, No. 11, 2005

Brunker et al.

Table 7. Selected NMR Data for the Complexes M(diphos*)(Ph)(I)^a

compd

diphos

δ(³¹P)

δ(¹³C) (Pd-C6H5)

3

a

b

c

d

e

f

Me-Duphos

Et-Duphos

i-Pr-Duphos

Me-BPE

Me-FerroLANE

Me-DuXantphos

67.8, 64.7 (J ) 27)

61.4, 58.5 (J ) 26)

62.4, 57.0 (J ) 23)

72.9, 61.5 (J ) 25)

41.0, 23.9 (J ) 32)

31.7 (trans)

159.3 (d, J ) 138)

158.2 (d, J ) 138)

156.4 (d, J ) 134)

158.9 (d, J ) 132)

153.5 (dd, J ) 122, 3)

nd

b

3

6.2, 27.1 (J ) 32, cis)

3

g

h

i

Et-FerroTANE

CyPF-t-Bu

PPF-t-Bu

46.4, 32.8 (J ) 29)

155.9 (dd, J ) 127, 5)

78.0, 13.0 (J ) 35)

152.0

nd

148.7 (m)

nd

74.3, 18.9 (J ) 40)

c

j

BoPhoz

79.6, -4.5 (J ) 32) (major)

8

1.8, 5.8 (J ) 37) (minor)

Ni-3a

Me-Duphos

75.0, 68.7 (J ) 26)

63.6, 56.8 (J ) 6)

Pt-3a^d

158.9 (dd, J ) 115, 7)

a

Solvent: CDCl3 for 3c,e,g-j, C6D6 for 3a,b,d and Ni-3a. Chemical shifts are given in ppm and coupling constants in Hz. n.d. ) not

b

determined. CD2Cl2, -50 °C. The trans to cis ratio is 3.2:1. However, in toluene, a neutral trans complex was observed (-20 °C): δ 30.8,

5.3 (AB quartet, J ) 417). 8:1 diastereomer ratio, from P NMR integration. In C6D6, JPt-P ) 1616 and 3754 Hz, respectively.

c

31

d

2

Figure 7. ORTEP diagram of one of the three independent

Figure 6. ORTEP diagram of Pd((R,R)-Me-Duphos)(Ph)-

I) (3a).

molecules in the unit cell of Pd((S,S)-Et-FerroTANE)(Ph)-

(I)‚0.33toluene (3g‚0.33(toluene)). The solvent molecule and

disorder in one of the ethyl groups are not shown.

(

Me-Duphos or by reaction of Pt(Me-Duphos)(Ph)(Cl)

4

1

(

prepared from Pt(COD)(Ph)(Cl) and crystallographi-

cally characterized; see the Supporting Information)

with excess NaI.

The trend in rates of PhI oxidative addition to the

M(Me-Duphos)(trans-stilbene) complexes (Ni, Pd . Pt)

is consistent with related observations in the literature.

However, the faster oxidative addition of the Pd complex

2

a, relative to Ni-2a, is unusual.⁴²Further study of the

mechanisms of oxidative addition will be required to

explain these results.

Characteristic NMR data for the phenyl iodide com-

31

plexes are summarized in Table 7. The P NMR spectra

showed two peaks with a small cis coupling constant

(

ca. 30 Hz). The Pd-bound phenyl group gave rise to a

13

characteristic C NMR resonance around 150 ppm with

a large trans JPC value (ca. 130 Hz), and little depen-

4

3

dence on the ligand.

Figure 8. ORTEP diagram of Pd((R,S)-PPF-t-Bu)(Ph)(I)‚

The crystal structures of several of these complexes

3a,c,g,h) were also determined (Figures 6-8, Tables

and 8, and the Supporting Information). All showed

2 2 2 2

CH Cl (3i‚CH Cl ). Hydrogen atoms and the solvent

(

3

molecule are omitted.

(

42) Grushin, V. V.; Alper, H. Chem. Rev. 1994, 94, 1047-1062.

43) Tschoerner, M.; Kunz, R. W.; Pregosin, P. S. Magn. Reson.

distorted-square-planar geometry with, in most cases,

somewhat longer Pd-P and Pd-I bonds in the sterically

(

Chem. 1999, 37, 91-97.

Chiral Palladium(0) trans-Stilbene Complexes

Organometallics, Vol. 24, No. 11, 2005 2739

Table 8. Selected Bond Lengths (Å) and Angles

NMR spectra were recorded on Varian 500 or 300 MHz

1

13

(

deg) in the Complexes Pd(diphos*)(Ph)(I)

spectrometers. H and C NMR chemical shifts are reported

relative to Me Si and were determined by reference to the

4

1

13

31

residual H or C solvent peaks. P NMR chemical shifts are

reported relative to H PO (85%), used as an external refer-

3

4

ence. All J values are given in Hz. Unless otherwise noted,

peaks in NMR spectra are singlets; other abbreviations used

are d ) doublet, t ) triplet, q ) quartet, m ) multiplet, and

quat ) quaternary. Infrared spectra were recorded on KBr

pellets with a Perkin-Elmer 1600 series FTIR instrument and

3

h‚

Cl

THF

3

g‚

CH

2

‚

3i‚

CH Cl

2

3

a

3c‚C

i-Pr-

6

D

6

0.33C

7

H

8

2

diphos

Me-

Duphos

Et-Ferro-_bCyPF-

PPF-

t-Bu

-1

are reported in cm . Elemental analyses were provided by

Duphos^a

TANE

t-Bu

a

Schwarzkopf Microanalytical Laboratory, or by Quantitative

Technologies, Inc. Mass spectra were obtained at the Univer-

sity of Illinois Urbana-Champaign.

Pd-P1

Pd-P2

Pd-C

Pd-I

2.2348(8) 2.2427(10) 2.2722(18) 2.3000(8) 2.249(2)

2.3182(8) 2.3151(12) 2.3768(19) 2.4151(8) 2.439(2)

2.084(3)

2.032(5)

2.056(7)

2.043(3)

2.065(9)

Literature procedures were used to prepare Pd((R,R)-Me-

2.6588(3) 2.6459(5) 2.6427(7) 2.6847(3) 2.6916(11)

1

1b

46

47

35

Duphos)Cl

2

,

Pd(COD)Cl

2

,

Pd(dba)

2

, Pd(TMEDA)(Ph)(I),

P-Pd-P 86.63(3)

C-Pd-I 92.92(9)

P1-Pd-C 89.11(9)

87.70(4)

100.54(6) 97.98(3)

97.02(8)

84.9(2)

84.5(2)

3

6

16d

Pd(PPh

phos)Cl

3

)

,

2

(Ph)(I), Pd(PPF-t-Bu)Cl

Ni(PPh

and Pt(COD)(Ph)(I), Me-FerroLANE, Me-DuXantphos,

and Pt(Me-Duphos)(trans-stilbene).

The complexes Pd(diphos*)Cl were prepared from Pd(COD)-

and the appropriate diphosphine. One example is described

2

(1i),

3

Ni((R,R)-Me-Du-

88.10(11) 86.5(2)

91.40(12) 85.6(2)

83.31(9)

87.76(9)

4

8

49

,⁵⁰Pt(COD)(Ph)(Cl)

2

3

)

2

(Ph)(Cl), Ni(PPh

)

4

1

17

18

P2-Pd-C 175.41(8) 178.88(15) 169.0(2)

P1-Pd-I 177.96(2) 179.40(5) 166.40(5) 149.52(2) 155.47(7)

P2-Pd-I 91.34(2) 92.79(3) 89.18(5) 99.07(2) 100.03(6)

162.80(10) 161.4(3)

1

3

2

a

_S_e_e_t_h_e_S_u_p_p_o_r_t_i_n_g_I_n_f_o_r_m_a_t_i_o_n_.b Average values; three in-

Cl

2

dependent molecules in the unit cell.

below, and synthetic details for the analogous compounds are

given in the Supporting Information.

Pd((R,R)-Et-Duphos)Cl

COD)Cl (201 mg, 0.704 mmol) in CH

R,R)-Et-Duphos (260 mg, 0.717 mmol) as a solution in CH

(2 mL). The precipitate dissolved immediately, and the

reaction mixture turned canary yellow. After it was stirred

for 1 h, the solution was concentrated to 0.5 mL and layered

with petroleum ether. Cooling at -30 °C overnight resulted

in a yellow oil that solidified upon trituration with petroleum

ether. The yellow solid was dried in vacuo, giving 352 mg (93%)

of the desired compound. Recrystallization from THF/petro-

leum ether gave analytically pure yellow crystals. Recrystal-

lization from acetone gave crystals of an acetone solvate

suitable for X-ray analysis.

2

(1b). To a stirred slurry of Pd-

crowded Josiphos complexes 3h,i. Significant deviations

of the P1-Pd-I angle from the ideal 180° (166.40(5),

(

Cl

2

Cl (2 mL) was added

2

-

1

49.52(2), and 155.47(7)°) occurred in complexes 3g-i,

2

consistent with the larger bite angles of the diphos-

phines (100.54(6), 97.98(3), and 97.02(8)°, respectively).

The structures of 3h,i are very similar to those of the

analogous bromide complexes Pd(PPF-t-Bu)(Ph)(Br) and

16a

Pd(CyPF-t-Bu)(Ph)(Br). As expected from the relative

trans influences of the ligands, the Pd-P bonds trans

to the phenyl group were longer than those trans to

4

iodide.

Conclusions

Anal. Calcd for C22

H

36

P

2

Cl

2

Pd: C, 48.95; H, 6.72. Found:

3

1

C, 49.06; H, 6.84. P{ H} NMR (CDCl

3

): δ 90.2. H NMR

): δ 7.78-7.72 (m, 2H, Ar), 7.69-7.62 (m, 2H, Ar),

.45-3.34 (m, 2H, CH), 2.55-2.28 (m, 6H, CH, CH ), 2.24-

.00 (m, 6H, CH ), 1.70-1.59 (m, 2H, CH ), 1.30-1.19 (m, 2H,

The complexes Pd(diphos*)(trans-stilbene) (2) were

prepared by reduction of the precursors Pd(diphos*)Cl2

1) in the presence of the alkene. These complexes,

(

3

2

CDCl

3

2

(

2

convenient sources of the zerovalent Pd(diphos*), are

catalyst precursors for asymmetric phosphination,¹¹and

we expect they will find other applications in asym-

metric catalysis. Their stability and the enantioface

selectivity in binding of trans-stilbene depended strongly

on the diphosphine. The rate of oxidative addition of PhI

to 2 to give the complexes Pd(diphos*)(Ph)(I) (3) also

depended on the diphosphine, being faster for ligands

with large bite angles and reduced steric bulk. These

oxidative additions were significantly faster than those

of Pd(diphos*)(dba), which was generated in situ. Oxi-

dative addition of PhI to the complexes M(Me-Duphos)-

2 2

CH ), 1.19-1.06 (m, 2H, CH ), 0.93 (t, J ) 7.5, 6H, Me), 0.85

13

1

(t, J ) 7.5, 6H, Me). C{ H} NMR (CDCl

37, quat), 132.9 (m, Ar), 132.8 (t, J ) 10, Ar), 50.3 (m, CH),

4.9 (m, CH), 34.2 (CH ), 33.1 (CH ), 23.3

CH ), 14.7 (t, J ) 6, Me), 13.8 (t, J ) 6, Me).

Pd((R,R)-i-Pr-Duphos)Cl (1c). Anal. Calcd for C26

3

): δ 141.1 (t, J )

4

(

2

2 2

), 25.5 (t, J ) 3, CH

2

H

44 2

P -

1

3

1

Cl

2

Pd: C, 52.41; H, 7.44. Found: C, 52.38; H, 7.66. P{ H}

1

NMR (CDCl

3 3

): δ 85.1. H NMR (CDCl ): δ 7.78-7.73 (m, 4H,

Ar), 3.48-3.34 (m, 2H, CH), 2.76-2.56 (m, 2H, CH), 2.52-

.14 (m, 8H, CH

H, Me), 1.05 (d, J ) 6.6, 6H, Me), 0.80 (d, J ) 6.6, 6H, Me),

3

.72 (d, J ) 6.6, 6H, Me). C{ H} NMR (CDCl ): δ 141.9 (t, J

2

6

0

2

), 1.90-1.58 (m, 4H, CH), 1.12 (d, J ) 6.6,

13

1

) 35, quat), 133.1 (t, J ) 10, Ar), 132.8 (m, Ar), 56.4 (m, CH),

51.1 (m, CH), 31.1 (CH ), 30.7 (m, CH ), 29.9 (m, CH), 28.2

(CH), 26.2 (t, J ) 4, Me), 24.9 (t, J ) 4, Me), 21.6 (t, J ) 5,

Me), 20.7 (t, J ) 3, Me).

(

trans-stilbene) (M ) Ni, Pd, Pt) occurred in the rate

2

order Pd > Ni . Pt. Crystallographic studies of com-

plexes 1-3 revealed a surprisingly small structural

dependence on the nature of the diphosphine.

Pd((R,R)-Me-BPE)Cl

PdCl : C, 38.60; H, 6.48. Found: C, 38.53; H, 6.72. P{ H}

NMR (CDCl

.37-2.08 (overlapping m, 6H), 2.00-1.77 (overlapping m, 6H),

2 28 2

(1d). Anal. Calcd for C14H P -

3

1

2

1

3 3

): δ 102.3. H NMR (CDCl ): δ 3.52 (m, 2H),

Experimental Section

2

General Experimental Details. Unless otherwise noted,

all reactions and manipulations were performed in dry glass-

ware under a nitrogen atmosphere at room temperature in a

drybox, or using standard Schlenk techniques. Petroleum ether

(

45) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;

Timmers, F. J. Organometallics 1996, 15, 1518-1520.

(46) Drew, D.; Doyle, J. R. Inorg. Synth. 1990, 28, 346-349.

(47) Rettig, M. F.; Maitlis, P. M. Inorg. Synth. 1990, 28, 110-113.

(48) Frenzen, G.; Reim, S.; Sippel, H.; Frauenrath, H. Z. Kristallogr.

New Cryst. Struct. 1999, 214, 123-124.

(

bp 38-53 °C), ether, THF, CH

2 2

Cl , and toluene were dried

and degassed using columns containing activated alumina.

4

5

(

49) Hidai, M.; Kashiwagi, T.; Ikeuchi, T.; Uchida, Y. J. Organomet.

(

44) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev.

Chem. 1971, 30, 279-282.

1

973, 10, 335-422.

(50) Ittel, S. D. Inorg. Synth. 1977, 17, 117-125.

2

740 Organometallics, Vol. 24, No. 11, 2005

Brunker et al.

solution in THF (2 mL) followed by NaBH(OMe) (233 mg, 1.83

1

.58 (dd, J ) 19, 7, 6H, Me), 1.49-1.36 (m, 2H), 1.26 (dd, J )

3

6, 7, 6H, Me). The low solubility of the complex precluded

mmol, 3 equiv) dissolved in THF (5 mL). The mixture turned

dark yellow-green immediately, and gas was evolved. After the

reaction mixture was stirred for 1 h at room temperature,

when it was completely homogenized, the solvent was removed

in vacuo and the residue was extracted with toluene (30 mL)

and filtered. The toluene was removed in vacuo, and the yellow

solid was dissolved in hexane and filtered again. Cooling of

the solution overnight (-25 °C) gave 240 mg (66%) of a 5.6:1

(a:b) mixture of diastereomers as a bright yellow solid. When

2 equiv of stilbene was used, the yield was comparable. The

NMR spectra are reported as a mixture of diastereomers,

unless otherwise indicated. Recrystallization from pentane

gave a sample for elemental analysis which contained 0.5 equiv

of pentane.

1

3

obtaining its C NMR spectrum.

2 32

Pd((S,S)-Me-FerroLANE)Cl (1e). Anal. Calcd for C22H -

FeP

2

PdCl

H} NMR (CDCl

2

: C, 44.67; H, 5.45. Found: C, 44.45; H, 5.38. ³¹P-

1

{

3 3

): δ 57.0. H NMR (CDCl ): δ 4.69 (2H, Cp),

4

.47 (2H, Cp), 4.34 (2H, Cp), 4.28 (2H, Cp), 3.95-3.85 (m, 2H),

.69-2.59 (m, 2H), 2.27-2.17 (m, 2H), 2.02-1.93 (m, 2H), 1.88

2

(

0

dd, J ) 20, 7, 6H, Me), 1.84-1.73 (m, 2H), 1.32-1.24 (m, 2H),

.91 (dd, J ) 17, 7, 6H, Me). ¹³C{ H} NMR (CDCl

apparent t, J ) 4, Cp CH), 75.3 (apparent t, J ) 8, Cp CH),

4.6 (Cp CH), 72.9 (apparent t, J ) 3, Cp CH), 68.1 (d, J ) 47,

Cp quat), 39.6 (m, CH), 35.8 (CH ), 35.3 (m, CH), 35.1 (CH ),

1.4 (apparent t, J ) 4, Me), 14.9 (Me).

Pd((S,S)-Me-DuXantphos)Cl (1f). Anal. Calcd for C27

OPdCl ‚CH Cl : C, 47.99; H, 5.47. Found: C, 48.12; H, 5.77.

P{ H} NMR (CD Cl , -20 °C): δ 49.2 (d, J ) 9), 36.6 (d, J )

). P{ H} NMR (CD Cl , 21 °C): δ 48.8 (br), 37.3 (br), 31.8.

, -20 °C): δ 7.60-7.56 (m, 3H, Ar), 7.34 (t, J

7, 1H, Ar), 7.28 (t of d, J ) 8, 2, 1H, Ar), 7.20 (t of d, J ) 8,

, 1H, Ar), 3.60-3.56 (m, 1H), 3.12-3.06 (m, 1H), 2.92-2.86

m, 2H), 2.49-2.39 (m, 1H), 2.33-2.25 (m, 1H), 2.01-1.95 (m,

H), 1.94 (overlapping previous m, dd, J ) 14, 7, 3H, phos-

pholane Me), 1.85 (3H, Xant Me), 1.83-1.65 (overlapping m,

H), 1.60 (dd, J ) 21, 7, 3H, phospholane Me), 1.40 (3H, Xant

Me), 1.36 (dd, J ) 19, 7, 3H, phospholane Me), 0.88 (dd, J )

4, 7, 3H phospholane Me).

Pd((S,S)-Et-FerroTANE)Cl

FePdCl

NMR (CDCl

1

3

): δ 76.0

(

7

2

36 2

H P -

2

Anal. Calcd for C32

H

40

P

2

Pd(C

5

H

12

)

0.5

:

C, 65.87; H, 7.37.

): δ 57.6 (a),

6 6

50.8 (b). H NMR (C D ): δ 7.43 (d, J ) 8, 4H, Ar), 7.33-7.27

31

1

31

1

2

Found: C, 65.97; H, 7.02. P{ H} NMR (C D

6 6

3

1

9

2

1

H NMR (CD

2

Cl

2

(m, 2H, Ar), 7.21-7.14 (m, 4H, Ar), 7.02-6.97 (m, 2H, Ar),

6.88-6.83 (m, 2H, Ar), 5.50 (d, J ) 2, 2H, CHdCH, a), 5.25

(d, J ) 2, 2H, CHdCH, b), 2.58-2.51 (m, 2H, CH, b), 2.40-

2.28 (m, 2H, CH, a), 2.26-2.16 (m, 2H, CH, b), 2.04-1.92 (m,

)

1

(

3

2H, CH, a), 1.92-1.80 (m, 4H, CH

a), 1.57-1.48 (m, 2H, CH , a), 1.38 (dd, J ) 20, 7, 6H, Me, a),

1.36-1.16 (m, 4H, CH ), 0.63 (dd, J ) 13, 7, 6H, Me, b), 0.55

(dd, J ) 19, 7, 6H, Me, b), 0.36 (dd, J ) 14, 7, 6H, Me, a).

2 2

, b), 1.66-1.57 (m, 4H, CH ,

2

3

2

1

3

1

6 6

C{ H} NMR (C D ): δ 147.4-147.3 (m, quat, Ar), 146.8-

2

(1g). Anal. Calcd for C24

36 2

H P -

1

146.1 (m, quat, Ar), 133.4 (m, CH, Ar, b), 133.2 (apparent t, J

) 5, CH, Ar, a), 128.9 (CH, Ar, a), 128.8 (CH, Ar, b), 128.2

(apparent t, J ) 2, CH, Ar), 125.1 (m, CH, Ar, b), 124.4

(apparent t, J ) 2, CH, Ar, a), 122.3 (m, CH, Ar, b), 121.9

(apparent t, J ) 2, CH, Ar, a), 64.2 (m, CHdCH, b), 60.6

(apparent t, J ) 10, CHdCH, a), 39.9 (m, CH, b), 39.8 (m, CH,

3

1

2

: C, 46.52; H, 5.86. Found: C, 46.53; H, 5.74. P{ H}

1

3 3

): δ 57.3. H NMR (CDCl ): δ 4.76 (2H), 4.59-

.57 (overlapping singlets, 4H), 4.32-4.27 (m, 2H), 4.21 (2H),

.62-2.57 (m, 2H), 2.47-2.24 (m, 6H), 2.18-2.07 (m, 2H), 1.26

1

3

): δ 76.6 (t, J ) 4, CH), 76.1-75.9 (m,

b), 38.1 (apparent t, J ) 7, CH, a), 37.1 (CH

2 2

, b), 36.9 (m, CH ,

a), 36.7 (m, CH , a), 36.6 (apparent t, J ) 7, CH, a), 20.5

2

(apparent t, J ) 12, Me, a), 17.5 (Me, b), 15.1 (Me, b), 15.0

(Me, a).

Pd((R,R)-Et-Duphos)(trans-stilbene) (2b). Anal. Calcd

2

H52FeP

2

-

for C36

H

48

P

2

Pd(C

6

H

14

)

0.5: C, 67.67; H, 8.01. Found: C, 67.66;

3

1

2

(CH

2

Cl

2

)

0.8: C, 49.26; H, 6.75. Found: C, 49.02; H, 6.92.

H, 7.66. P{ H} NMR (C

(C

D

6 6

): δ 51.5 (a), 46.4 (b). H NMR

1

3

): δ 114.4 (d, J ) 11), 32.6 (br). H NMR

6 6

D ): δ 7.42-7.32 (m, 6H, Ar), 7.20-7.14 (m, 4H, Ar), 7.04-

3

): δ 4.91 (1H), 4.58 (1H), 4.56 (1H), 4.30 (5H), 3.10 (m,

H), 2.60 (br, 1H), 2.39-2.34 (m, 1H), 2.26 (br, 2H), 2.13-

6.98 (m, 2H, Ar), 6.95-6.90 (m, 2H, Ar, b), 6.87-6.82 (m, 2H,

Ar, a), 5.45 (d, J ) 2, 2H, CHdCH, a), 5.23 (d, J ) 2, 2H,

CHdCH, b), 2.44-2.36 (m, 2H, b), 2.26-2.14 (m, 2H, a), 2.14-

1.92 (m, 2H), 1.94-1.70 (m, 5H), 1.40-1.26 (m, 4H), 1.26-

1.14 (m, 2H), 0.97 (t, J ) 7.5, 6H, Me, a), 0.88-0.76 (m, 3H),

0.71-0.61 (m, 2H, overlapped), 0.65 (t, J ) 7, 6H, b, over-

lapped), 0.55 (t, J ) 7.5, 6H, Me, b), 0.48 (t, J ) 7.5, 6H, Me,

1

3

1

(

3

2

Cp), 69.6 (Cp), 69.5 (Cp), 66.1 (Cp), 41.9, 40.9 (d, J ) 12),

4.7 (d, J ) 9), 34.3, 32.3, 31.4, 30.3, 29.5, 28.4, 27.9, 27.6,

7.1 (d, J ) 14), 26.5, 25.9, 22.6, 18.3, 15.5, 14.3.

1

3

1

6 6

a). C{ H} NMR (C D ): δ 147.1 (t, J ) 3, quat), 146.6 (t, J )

Pd((R,S)-BoPhoz)Cl

PdCl (CH Cl 0.3: C, 55.02; H, 4.41; N, 1.72. Found: C, 55.52;

H, 4.68; N, 1.68. P{ H} NMR (CDCl

2

(1j). Anal. Calcd for C37

H

35NFeP

2

-

29, quat), 133.6 (t, J ) 4, Ar), 128.8 (Ar, a), 128.7 (Ar, b), 128.2

(t, J ) 2, Ar), 124.9 (Ar, b), 124.3 (t, J ) 2, Ar, a), 122.1 (Ar,

b), 121.6 (t, J ) 2, Ar, a), 63.5 (CHdCH, b), 60.2 (t, J ) 10,

CHdCH), 48.0 (CH, b), 47.4 (CH, b), 46.6 (t, J ) 7, CH, a),

2

)

3

1

3

): δ 85.2 (d, J ) 25),

3

4.5 (d, J ) 25). H NMR (CDCl ): δ 8.05 (br, 2H), 7.73 (br,

1

2

4

H), 7.54 (br, 6H), 7.43-7.39 (br, 5H), 7.31 (br, 1H), 7.05 (br,

H), 6.83 (br, 2H), 5.42 (br, 1H), 4.58 (br, 1H), 4.38 (br, 1H),

.04 (5H), 3.72 (1H), 2.15 (d, J ) 7, 3H), 0.93 (br, 3H). ¹³C-

44.0 (t, J ) 7, CH, a), 34.7 (CH

a), 33.8 (CH , b), 29.3 (t, J ) 12, CH

a), 14.6 (t, J ) 6, Me), 14.3 (t, J ) 4, Me).

2

, b), 34.3 (CH

2

, a), 34.2 (CH

2

,

2

), 24.3 (CH

2

, b), 23.8 (CH

2

1

{

H} NMR (CDCl

Ar), 134.2 (d, J ) 11, Ar), 133.5 (Ar), 133.2 (d, J ) 10, Ar),

33.1 (d, J ) 5, Ar), 131.9 (Ar), 131.5 (Ar), 131.3 (Ar), 131.0

d, J ) 2, Ar), 130.7 (Ar), 129.1 (d, J ) 11, Ar), 128.6 (Ar),

3

): δ 135.4 (d, J ) 10, Ar), 134.4 (d, J ) 11,

Pd((R,R)-i-Pr-Duphos)(trans-stilbene) (2c). Anal. Calcd

for C H P Pd: C, 68.13; H, 8.00. Found: C, 68.00; H, 8.07.

4

0

56

2

3

1

(

6 6 6 6

P{ H} NMR (C D ): δ 47.6 (b), 44.7 (a). H NMR (C D ): δ

7.46-7.36 (m, 6H, Ar), 7.22-7.16 (m, 4H, Ar), 7.01-6.97 (m,

2H, Ar), 6.89-6.85 (m, 2H, Ar), 5.34 (d, J ) 2, 2H, CHdCH,

a), 5.18 (d, J ) 2, 2H, CHdCH, b), 2.31-2.22 (m, 2H), 2.16-

2.07 (m, 2H), 2.07-1.96 (m, 2H), 1.86-1.76 (m, 2H), 1.52-

1.34 (m, 4H), 1.31 (d, J ) 6.5, 6H, Me), 1.26-1.18 (m, 2H),

1.16-1.07 (m, 2H), 1.02 (d, J ) 6.5, 6H, Me), 0.48 (d, J ) 6.5,

128.3 (d, J ) 7, Ar), 128.2 (d, J ) 7, Ar), 127.1 (d, J ) 12, Ar),

76.1 (Cp), 72.3 (Cp), 71.9 (Cp), 71.2 (Cp), 70.3 (d, J ) 7, Cp),

69.4 (d, J ) 7, Cp), 53.2 (d, J ) 16), 29.3 (d, J ) 6), 13.9.

The complexes Pd(diphos*)(trans-stilbene) were prepared by

2 3

treatment of Pd(diphos*)Cl with NaBH(OMe) in the presence

1

3

1

of stilbene in THF. A representative procedure is included

below, with synthetic details for the analogous compounds in

the Supporting Information.

Pd((R,R)-Me-Duphos)(trans-stilbene) (2a). To a stirred

2

slurry of Pd((R,R)-Me-Duphos)Cl (295 mg, 0.61 mmol) in THF

6 6

6H, Me), 0.36 (d, J ) 6.5, 6H, Me). C{ H} NMR (C D ): δ

147.4 (dd, J ) 28, 27, quat), 146.7 (apparent t, J ) 2, quat),

133.9 (apparent t, J ) 4, Ar), 128.7 (Ar), 128.3 (Ar), 124.5

(apparent t, J ) 2, Ar), 121.7 (Ar), 62.9 (apparent t, J ) 11,

CHdCH), 52.8 (apparent t, J ) 6, CH), 50.6 (apparent t, J )

(

2 mL) was added trans-stilbene (111 mg, 0.616 mmol) as a

2 2

7, CH), 32.5 (CH ), 31.7 (apparent t, J ) 9, CH), 28.9 (CH ),

Chiral Palladium(0) trans-Stilbene Complexes

Organometallics, Vol. 24, No. 11, 2005 2741

2

5

8.6 (CH), 24.7 (apparent t, J ) 4, Me), 24.3 (apparent t, J )

, Me), 21.5 (apparent t, J ) 3, Me), 19.8 (apparent t, J ) 5,

filtered, and the solution was pumped to dryness in vacuo to

give 49 mg of crude material. This was characterized by NMR

spectroscopy and showed resonances consistent with two

diastereomers of Pd(Me-DuXantphos)(trans-stilbene). In sepa-

rate experiments, small amounts of free ligand were always

observed in the crude product.

Me).

Pd(Me-BPE)(trans-stilbene) (2d). Anal. Calcd for C28

Pd: C, 61.71; H, 7.40. Found: C, 61.50; H, 7.52. P{ H} NMR

40 2

H P -

31

1

(

C

6

D

6

): δ 55.8 (A), 45.3 (B) (diastereomer ratio 2.5:1). H NMR

): δ 7.40 (m, 4H, Ar, A and B), 7.15 (m, 4H, Ar, A and

3

1

6

D

6

6 6

P{ H} NMR (C D , 21 °C): δ 31.6 (A, br), 26.5 (B, v. br)

B), 6.89 (m, 2H, Ar, A and B), 5.44 (apparent d, J ) 2, 2H,

stilbene CH, A), 5.40 (apparent d, J ) 2, 2H, stilbene CH, B),

(two sharp singlets at 27.0 and 26.1 were reproducibly

observed in separate experiments overlying the resonance due

31

1

2

1

.28-2.22 (m, 2H, B), 1.85-1.77 (m, 2H, A), 1.70-1.66 (m,

H, B), 1.64-1.52 (m, 4H, A), 1.50-1.42 (m, 2H, A), 1.39-

.34 (m, 2H, B), 1.28 (dd, J ) 20, 8, 6H, Me), 1.27-1.20

to B); ratio A:B 2.8:1. P{ H} NMR (C

6

D

5

CD

3

, -30 °C): δ 30.9

(A), 26.7 (B); ratio A:B 4.0:1. Selected H NMR (C , 21 °C):

δ 4.9 (br, stilbene CH, A), 4.7 (br, stilbene CH, B). Selected H

NMR (C CD

1

6 6

D

1

(

4

partially obscured m, 2H, A), 1.14-1.06 (m, B), 1.05-0.95 (m,

6

D

5

3

, -30 °C): δ 4.81 (m, stilbene CH, A), 4.72 (m,

H, A), 0.91 (dd, J ) 13, 8, 6H, Me, B), 0.71-0.66 (m, 2H, A),

.56 (dd, J ) 13, 7, 6H, A), 0.45 (dd, J ) 19, 8, 6H, B). Not all

stilbene CH, B); ratio A:B 4.3:1.

0

Attempts to recrystallize this material from hexane, toluene/

hexane, or diethyl ether/hexane mixtures were unsuccessful

and resulted in decomposition, as indicated by additional peaks

the protons associated with B could be identified due to peak

1

3

1

6 6

overlap. C{ H} NMR (C D ): δ 147.8 (apparent t, J ) 2, Ar

3

1

quat, B), 147.4 (apparent t, J ) 2, Ar quat, A), 128.3 (Ar CH,

B), 128.2 (Ar CH, A), 125.0 (t, J ) 2, Ar CH, B), 124.5 (t, J )

in the P{ H} NMR spectrum; in particular, an additional

sharp peak was observed at δ 35.2 (C CD ). To further

characterize the crude product, it was treated with PhI. Crude

6

D

5

3

2

6

3

, Ar CH, A), 122.1 (Ar CH, B), 121.9 (t, J ) 2, Ar CH, A),

2.6 (t, J ) 11, stilbene CH, B), 60.7 (t, J ) 10, stilbene CH),

8.6 (apparent t, J ) 6, CH B), 36.8 (apparent t, J ) 7, CH

-

5

Pd(Me-DuXantphos)(trans-stilbene) (27 mg, 3.7 × 10 mol)

was dissolved in toluene (1 mL), and PhI (6.7 µL, 6.0 × 10

mol, 1.6 equiv) was added by microliter syringe. The reaction

-

5

A), 36.3 (CH

2

B), 36.2 (CH

A), 35.9 (CH A), 34.0 (apparent t, J ) 6, CH A),

4.0 (apparent t, J ) 16, CH A), 23.0 (apparent t, J ) 16,

2

B), 36.1 (apparent t, J ) 8, CH B),

3

1

3

2

6.0 (CH

2

mixture was monitored by P{ H} NMR spectroscopy. After

5 min peaks consistent with trans-Pd(Me-DuXantphos)(Ph)-

(I) (3f) were observed and the spectrum did not change for a

further 1 h after the addition. See below, and the Results and

Discussion, for details of the characterization of 3f.

2

CH B), 21.1 (apparent t, J ) 11, Me, A), 18.9 (apparent t, J

)

11, Me, B), 14.5 (Me, B), 14.2 (Me A).

Pd((S,S)-Me-FerroLANE)(trans-stilbene) (2e). Anal.

Calcd for C36

H, 6.60. P{ H} NMR (C

mer ratio 6.4:1). H NMR (C

7

H

44FeP

2

Pd: C, 61.69; H, 6.33. Found: C, 61.73;

): δ 36.2 (A), 32.5 (B) (diastereo-

): δ 7.43 (d, J ) 8, 4H, Ar, A),

.37 (d, J ) 8, 4H, Ar, B), 7.19 (partially obscured, 4H, Ar, B),

.18 (t, J ) 8, 4H Ar, A), 7.00 (t, J ) 8, 2H, Ar, B), 6.93 (t, J

8, 2H, Ar, A), 5.02 (m, 2H, stilbene CH, A), 5.00 (m, 2H,

stilbene CH, B), 4.21 (m, 1H, Cp, B), 4.13 (m, 1H, Cp, B), 4.08

overlapping m, 2H, Cp, A), 3.95 (partially obscured m, 1H,

Pd((S,S)-Et-FerroTANE)(trans-stilbene) (2g). Anal.

3

1

6

D

6

Calcd for C38

H, 6.47. P{ H} NMR (C D

6 6

H

48FeP

2

Pd: C, 62.61; H, 6.64. Found: C, 62.45;

): δ 44.1 (a), 37.7 (b) (diastereomer

6 6

ratio 10.3:1). H NMR (C D ): δ 7.48-7.46 (m, 4H, Ar), 7.34-

1

31

1

6

D

6

1

7.31 (m, 4H, Ar), 7.01 (m, 2H, Ar), 5.33 (CHdCH, 2H, a), 5.30

(CHdCH, 2H, b), 4.33 (Cp, 2H), 4.24 (Cp, 2H), 4.19 (m, Cp,

4H), 2.44-2.40 (m, 2H), 2.34-2.30 (m, 6H), 2.09-2.05 (m, 2H),

2.04-1.99 (m, 2H), 1.47 (t, J ) 7, 6H, Me), 1.08-1.00 (m, 2H),

)

(

1

3

1

Cp, B), 3.93 (m, 1H, Cp, A), 3.78 (m, 1H, Cp, B), 3.74 (m, 1H,

Cp, A), 2.45-2.36 (m, 2H, A), 2.31-2.24 (m, 2H, B), 2.13-

0.99-0.88 (m, 2H), 0.48 (t, J ) 7, 6H, Me). C{ H} NMR

(toluene-d ): δ 146.4, 129.2 (b), 128.33, 128.28 (b), 125.4 (b),

8

2

1

.05 (m, 2H, A), 1.94-1.89 (m, 2H, B), 1.82-1.71 (m, 2H, A),

.69-1.61 (m, 2H, A), 1.58 (dd, J ) 20, 7, 6H, Me, A), 1.30-

.22 (m, 2H, A), 1.20-1.11 (m, 2H, A), 1.08 (dd, J ) 13, 7, 6H,

125.0, 122.8, 77.8 (m), 77.4 (apparent t, J ) 12), 73.4 (b), 73.2

(apparent t, J ) 4), 71.9 (b), 71.3, 70.1 (b), 70.0, 64.8 (apparent

t, J ) 10, stilbene CH), 36.3 (apparent t, J ) 6), 35.1 (m), 34.5

(b), 33.9 (m), 28.5 (apparent t, J ) 7), 25.6, 22.8 (b), 14.6

(apparent t, J ) 6), 14.3 (b), 12.6 (b) 11.7 (apparent t, J ) 4).

Pd(CyPF-t-Bu)(trans-stilbene) (2h). Anal. Calcd for

C H FeP Pd(C H )₀_.₂₅: C, 67.08; H, 7.62. Found: C, 67.12;

Me, B), 0.88-0.83 (m, 2H, B), 0.59 (dd, J ) 19, 7, 6H, Me, B),

.37 (dd, J ) 14, 7, 6H, Me, A). ¹³C{ H} NMR (C

1

D ): δ 147.1

6 6

0

(m, Ar quat, B), 146.8 (apparent t, J ) 2, Ar quat, A), 128.5

Ar, B), 128.1 (Ar, A), 125.0 (Ar, B), 124.8 (apparent t, J ) 2,

(

4

6

64

2

14 12

3

1

Ar, A), 122.9 (Ar, B), 122.7 (Ar, A), 78.3 (m, Cp quat, B), 78.1

m, Cp quat, A), 77.4 (m, Cp, A), 72.7 (m, Cp, B), 72.5 (apparent

6 6

H, 8.04. P{ H} NMR (C D ; two diastereomers, 40:1 ratio):

1

(

δ 76.5 (d, J ) 5), 20.3 (br) (major); 82.9, 18.6 (minor). H NMR

(C D ): δ 7.43 (d, J ) 8, 2H), 7.37 (d, J ) 8, 2H), 7.21 (t, J )

t, J ) 4, Cp, A), 71.6 (m, Cp, B), 71.3 (apparent t, J ) 2, Cp,

A), 69.6 (Cp, A), 64.7 (m, stilbene CH B), 63.6 (m, stilbene CH,

6

8, 2H), 7.18-7.14 (m, 2 H, overlapping with solvent), 6.97 (t,

J ) 7, 1H), 6.91 (t, J ) 7, 1H), 4.78 (br, 1H), 4.68 (m, 1H),

4.26 (Cp, 1H), 4.09 (Cp, 1H), 4.06 (Cp, 5H), 4.04 (Cp, 5H,

minor), 3.97 (t, J ) 3, Cp, 1H), 2.98 (m, 1H), 2.16 (br, 2H),

1.93-1.77 (m, 8H), 1.73 (t, J ) 7, 3H), 1.58 (m, 5H), 1.53 (d,

A), 38.3 (m, CH, B), 36.3 (CH

A), 35.7 (d, J ) 2, CH , A), 35.6 (m, CH

m, CH, A), 23.4 (m, Me, A), 22.7 (Me, B), 14.9 (Me, B), 13.7

Me, A). Only those resonances from B that could be distin-

2

, B), 36.0 (CH

2

, A), 35.9 (m, CH,

2

B), 34.6 (CH, B), 33.8

(

1

3

1

guished are listed.

J ) 12, 9H), 1.42-1.00 (m, 7H), 0.63 (d, J ) 12, 9H). C{ H}

NMR (C ): δ 149.1 (m, Ar), 148.6 (dd, J ) 6, 2, Ar), 128.7-

128.2 (m, overlapping C peaks, Ar), 125.8 (d, J ) 2, Ar),

In certain syntheses, subsequent crops of material contained

a variable, but small (less than 7%), amount of an unknown

6 6

D

6 6

D

1

impurity that was observed by H NMR spectroscopy. H NMR

): δ 4.62 (m, Cp), 4.60 (m, Cp), 4.46 (m, Cp), 3.87 (m,

125.2 (d, J ) 3, Ar), 122.9 (d, J ) 2, Ar), 122.7 (d, J ) 3, Ar),

110.5 (Ar), 98.0 (dd, J ) 6, 21, Cp), 76.3 (Cp), 73.3 (Cp), 70.1

(Cp), 70.0 (Cp, minor), 69.7 (Cp), 67.9 (d, J ) 4, Cp), 66.3 (d,

J ) 28, stilbene CH), 63.7 (dd, J ) 5, 27, stilbene CH), 38.0

(d, J ) 4), 37.4 (d, J ) 5), 37.3 (d, J ) 5), 36.8 (t, J ) 4), 36.7,

35.5 (m), 34.8, 31.6 (br), 30.6 (br), 30.0 (d, J ) 7), 29.8, 28.1

6 6

(C D

Cp), 1.35 (dd, J ) 17, 7, Me), 0.61 (dd, J ) 14, 7, Me).

Pd(Me-DuXantphos)(trans-stilbene) (2f). Pd(Me-Du-

Xantphos)Cl

-

5

2

-

(48 mg, 7.3 × 10 mol) and trans-stilbene (15

5

mg, 8.3 × 10 mol) were slurried in THF (2 mL), and NaBH-

-

4

1

(

OMe)

portions. Immediately on addition the solution turned red-

brown and H evolution was observed. Residual NaBH(OMe)

3

(28 mg, 2.2 × 10 mol) was added as a solid in small

(m), 27.8, 27.6 (d, J ) 6), 27.5, 26.4, 18.3 (d, J ) 6), 12.0. H-

3

1

{ P} NMR (C

6 6

D ) (selected peaks): δ 4.75 (d, J ) 10), 4.65 (d,

J ) 10), 1.67 (d, J ) 10), 1.32 (9H), 0.60 (9H).

2

3

1

31

was added to the mixture in THF (1 mL), and then the solution

was stirred for 1 h. All volatiles were then removed in vacuo,

and the residue was extracted with toluene (6 mL). The

solution was filtered through Celite, and again all volatiles

were removed in vacuo to yield a dark brown solid. The solid

was extracted with petroleum ether (6 mL), the extract was

Selective H{ P} decoupling experiments enabled identifi-

3

1

cation of the P NMR resonances for both 2h and 2i. Here,

decoupling the P(t-Bu) signal at δ 76.5 collapsed the t-Bu

2

signals into singlets as well as simplifying the CHMe reso-

nance, while decoupling the other peak did not affect these

signals.

2742 Organometallics, Vol. 24, No. 11, 2005

Brunker et al.

Pd(PPF-t-Bu)(trans-stilbene) (2i). Anal. Calcd for C46

H

52

-

7, 4H, stilbene Ar), 7.24 (m, 2H, Ar), 7.17 (t, J ) 7, 4H, stilbene

Ar), 6.99 (m, 2H, Ar), 6.90 (t, J ) 7, 2H, stilbene Ar), 4.67

(2H, stilbene CH (a)), 4.32 (2H, stilbene CH (b)), 2.35 (m, 2H),

1.97 (m, 2H), 1.66 (m, 2H), 1.45 (m, 6H, Me), 1.45-1.32 (m,

Pd: C, 66.64; H, 6.32. Found: C, 66.03; H, 6.53. ³¹P{ H}

1

FeP

NMR (C

diastereomer was not observed in the P NMR spectrum,

2

6

D ): δ 77.4 (d, J ) 14), 9.6 (d, J ) 14). The minor

3

1

13

1

perhaps because of peak overlap. H NMR (C

6 6

D ): δ 7.53 (t, J

2H), 1.32-1.24 (m, 4H), 0.38 (m, 6H, Me). C{ H} NMR

(C ): δ 147.8 (apparent t, J ) 2, stilbene Ar quat), 147.3

)

8, 2H), 7.34 (d, J ) 8, 2H), 7.30-7.26 (m, 2H), 7.21 (m, 2H),

6 6

D

7

6

1

.18-7.14 (m, 2H), 7.10 (t, J ) 7, 1H), 7.06-6.98 (m, 6H),

.84-6.79 (m, 3H), 4.97 (m, 1H), 4.33 (m, 1H), 4.26 (m, Cp,

H), 4.09 (Cp, 1H), 3.99 (m, Cp, 1H), 3.51 (Cp, minor diaste-

(apparent t, J ) 31, Ar quat), 131.8 (apparent t, J ) 6, Ar),

128.7 (Ar), 128.3 (Ar), 123.9 (apparent t, J ) 2, Ar), 121.4

(apparent t, J ) 2, Ar), 52.5 (apparent t, J ) 9, stilbene CH),

reomer, 5H), 3.43 (Cp, 5H), 3.33 (m, 1H), 1.69 (t, J ) 7, 3H),

2 2

38.3 (apparent t, J ) 12, CH), 37.20 (CH ), 37.16 (CH ), 35.4

.53 (d, J ) 12, 9H), 0.75 (d, J ) 12, 9H). ¹³C{ H} NMR

): δ 146.9 (dd, J ) 6, 2, Ar), 146.5 (dd, J ) 5, 2 Ar), 141.5

dd, J ) 30, 4, Ar), 140.0 (d, J ) 25, Ar), 135.9 (d, J ) 18, Ar),

31.4 (d, J ) 12, Ar), 129.2 (Ar), 128.4 (d, J ) 1, Ar), 128.3

Ar), 128.2-127.7 (m, overlapping C peaks), 127.5 (Ar),

25.1 (d, J ) 2, Ar), 124.4 (d, J ) 2, Ar), 122.9 (Ar), 122.1

1

(apparent t, J ) 10, CH), 19.8 (apparent t, J ) 9, Me), 15.0

(Me).

1

(C

D

6 6

(

1

(

1

Ni((R,R)-Me-Duphos)(COD) (4). Ni(COD) (50 mg, 0.18

2

mmol) was stirred as a slurry in hexane (1 mL), and a solution

of (R,R)-Me-Duphos (55 mg, 0.18 mmol) in hexane (2 mL) was

added dropwise. Immediately all the solid dissolved and an

orange solution formed; it was stirred for 20 min and then

filtered through Celite. The solution was reduced to ca. 2 mL

in vacuo and stored at -30 °C overnight to yield the product

as orange crystalline blocks, suitable for X-ray crystallography,

which were isolated and dried in vacuo. Concentration of the

supernatant and cooling to -30 °C yielded a second crop of

solid. Yield: 60 mg (in 2 crops, 72%).

6 6

D

(

Ar), 97.9 (dd, J ) 6, 26, Cp), 79.6 (dd, J ) 2, 20, Cp), 74.6

Cp), 70.2 (Cp), 69.6 (d, J ) 8, Cp), 69.5 (dd, J ) 5, 23), 68.6

br, d, J ) 28), 67.8 (d, J ) 4, Cp), 36.7 (dd, J ) 4, 1), 36.3 (d,

J ) 7), 36.0 (t, J ) 4.5), 31.2 (d, J ) 9), 30.9 (d, J ) 8), 17.6 (d,

J ) 3).

Pd(BoPhoz)(trans-stilbene) (2j). ³¹P{ H} NMR (C

1

6 6

D ; two

diastereomers, in 2:1 ratio): major, δ 90.0 (d, J ) 23), 8.6 (d,

1

J ) 23); minor, δ 90.1 (d, J ) 21), 8.2 (d, J ) 21). H NMR

40 2

Anal. Calcd for C26H P Ni: C, 65.99; H, 8.52. Found: C,

6 6

(C D ): δ 8.03 (br, 1H, Ar), 7.84 (d, J ) 8, 2H, Ar), 7.81 (t, J

63.01; H, 8.64. Despite several attempts using crystalline

3

1

)

8, 2H, Ar), 7.62 (t, J ) 8, 2H, Ar), 7.26-7.22 (m, 4H, Ar),

.91-6.84 (m, 4H, Ar), 6.81 (br, 5H, Ar), 6.75 (m, 5H, Ar), 6.56

t, J ) 6, 2H, Ar), 6.35-6.31 (m, 1H, Ar), 6.29-6.28 (m, Cp-

material, a satisfactory C analysis could not be obtained. P-

1

6

6 6 6 6

{ H} NMR (C D ): δ 62.9. H NMR (C D ): δ 7.44-7.41 (m,

(

2H, Ar), 7.09-7.07 (m, 2H, Ar), 5.32-5.27 (m, 2H, alkene CH),

4.09-4.03 (m, 2H, alkene CH), 2.76-2.70 (m, 4H), 2.68-2.61

(m, 2H), 2.49-2.42 (m, 2H), 2.37-2.33 (m, 2H), 2.30-2.23 (m,

2H), 2.18-2.11 (m, 2H), 1.90-1.85 (m, 2H), 1.58-1.48 (m, 4H),

1.37 (dd, J ) 16, 7, 6H, Me), 0.58 (dd, J ) 12, 7, 6H, Me).

CH(Me)), 6.01 (t, J ) 9, 2H, Ar), 5.86 (m, 1H, minor stilbene

CH), 5.52 (br, 1H, minor stilbene CH), 5.35-5.31 (m, 1H,

stilbene CH), 5.21-5.16 (m, 1H, stilbene CH), 4.13 (1H, Cp),

4

(

.08 (1H, Cp), 4.03 (1H, Cp, minor), 3.96 (1H, Cp, minor), 3.73

5H, Cp, minor), 3.60 (1H, Cp, minor), 3.58 (1H, Cp), 3.46 (5H,

Cp), 2.18 (d, J ) 7, 3H, minor), 2.11 (d, J ) 7, 3H), 1.33 (d, J

1

3

1

6 6

C{ H} NMR (C D ): δ 149.0 (m, Ar quat), 131.4 (apparent t,

J ) 6, Ar), 128.1 (Ar), 83.9 (t, J ) 2, alkene CH), 79.0 (t, J )

4, alkene CH), 40.4 (apparent t, J ) 9, CH), 37.8 (dd, J ) 9,

1

3

1

)

7, 3H), 1.13 (d, J ) 7, 3H, minor). C{ H} NMR (C

48.2 (m, Ar), 144.9 (m, Ar), 140.8 (m, Ar), 140.1 (d, J ) 9,

Ar), 139.7 (Ar), 139.5 (Ar), 135.2 (d, J ) 17, Ar), 132.9 (d, J )

6, Ar), 132.6 (d, J ) 16, Ar), 132.3 (d, J ) 17, Ar), 130.3 (d,

J ) 15, Ar), 129.5 (Ar), 129.2 (Ar), 129.0 (Ar), 128.5 (Ar), 128.3

Ar), 128.2-127.9 (m, overlapping C peaks), 127.7 (d, J )

5, Ar), 127.5 (d, J ) 7, Ar), 125.9 (m, Ar), 125.6 (m, Ar, minor),

6 6

D ): δ

1

11, CH), 37.6 (CH

30.2 (apparent t, J ) 2, CH

14.6 (Me).

2

), 35.8 (CH

2

), 35.3 (apparent t, J ) 6, CH

2

),

2

), 19.9 (apparent t, J ) 8, Me),

1

Ni((R,R)-Me-Duphos) (5). Ni(COD) (50 mg, 0.18 mmol)

2

(

6

D

6

was stirred as a slurry in hexane (1 mL), and a solution of

(R,R)-Me-Duphos (111 mg, 0.36 mmol) in hexane (2 mL) was

added dropwise. Immediately all the solid dissolved and an

orange solution formed; it was transferred to an ampule, which

was sealed and heated at 50 °C for 5 h. The orange solution

was then cooled to room temperature and filtered through

Celite. The solution was reduced to ca. 2 mL in vacuo and

stored at -30 °C overnight to yield the product as dark orange

crystals, whose high solubility reduced the yield (66 mg in 2

crops, 54%). A solution of this complex decomposed quickly in

air.

1

9

7

24.6 (m, Ar, minor), 124.4 (m, Ar), 123.7 (Ar), 122.8 (m, Ar),

7.7 (m, Cp), 75.5 (Cp), 73.2 (m, Cp), 71.9 (m, stilbene CH),

0.3 (Cp, 5C, major), 70.2 (Cp, 5C, minor), 69.1 (m, Cp), 68.2

(

m, Cp), 66.5 (m, stilbene CH), 57.7 (m, Cp CH(Me)N-), 30.4

Me, major), 30.2 (Me, minor), 29.4 (N-Me, major), 29.0 (N-

Me, minor). Note: only selected peaks of the minor diastereo-

mer are reported.

Ni((R,R)-Me-Duphos)(trans-stilbene) (Ni-2a). Ni((R,R)-

2

Me-Duphos)Cl (150 mg, 0.34 mmol) and trans-stilbene (68 mg,

0

.38 mmol) were stirred as a slurry in THF (4 mL). NaBH-

56 4

Anal. Calcd for C36H P Ni: C, 64.40; H, 8.41. Found: C,

63.71; H, 8.64. P{ H} NMR (C D ): δ 68.5. H NMR (C D ):

6 6 6 6

3

1

(

OMe) (132 mg, 1.03 mmol) was added as a solid, and any

3

residual borohydride was then washed into the reaction

mixture with THF (2 mL). The reaction mixture immediately

turned brown, and gas evolved. Stirring was continued for a

further 1.5 h, and then all volatiles were removed in vacuo.

The mixture was extracted with toluene (8 mL) and filtered

through Celite, and the resulting dark brown solution was

pumped to dryness in vacuo. The orange residue was then

extracted with petroleum ether (12 mL), filtered through

Celite, and reduced in volume to ca. 6 mL in vacuo. After

storage overnight at -30 °C, the product was isolated as fine

orange needles (90 mg), suitable for X-ray crystallography.

Concentration of the supernatant to 3 mL in volume and

cooling to -30 °C yielded a second crop of solid. Total yield

δ 7.49 (m, 4H, Ar), 7.09 (m, 4H, Ar), 2.48 (m, 4H), 2.26-2.21

(m, 8H), 1.97 (m, 4H), 1.66-1.55 (overlapping m, 8H), 1.26-

1

3

1

1.20 (m, 12H, Me), 0.88-0.85 (m, 12H, Me). C{ H} NMR

(C ): δ 132.0 (m, Ar quat), 130.1 (br, Ar), 127.0 (Ar), 41.0

6 6

D

(quintet, J ) 9), 36.93 (quintet, J ) 6), 36.88, 36.5, 20.9 (m,

Me), 15.8 (Me).

Addition of PhI to Pd(Diphos*)(trans-stilbene) Com-

plexes. Sample Procedure. To a solution of Pd((R,R)-Me-

Duphos)(trans-stilbene) (2a; 40.7 mg, 0.069 mmol) in toluene

(1 mL) was added PhI (12 µL, 21.9 mg, 0.107 mmol, 1.5 equiv)

via syringe. The progress of the reaction was monitored by

3

1

P{ H} NMR. With this and other diphos* ligands, oxidative

addition occurred to give Pd(Diphos*)(Ph)(I) as the major

product; with the Duphos ligands an impurity formulated as

(

two crops): 110 mg (0.20 mmol, 59%). Despite repeated

3

attempts, we were unable to get satisfactory elemental analy-

ses for this complex.

Pd(Duphos)I was also formed. See Table 6 for details. In

2

some experiments, additional trans-stilbene was added to 2a

before treatment with PhI.

Formation of Pd(L*)(dba) in Situ and Oxidative Ad-

2

dition of PhI. Sample Procedure. Pd(dba) (17 mg, 0.03

Anal. Calcd for C32

H

40

P

2

Ni: C, 70.48; H, 7.39. Found: C,

9.42; H, 7.63. P{ H} NMR (C ): δ 68.9 (a), 60.9 (b);

diastereomer ratio (a):(b) 55:1. H NMR (C ): δ 7.36 (d, J )

3

1

6

D

6 6

1

6

D

6

Chiral Palladium(0) trans-Stilbene Complexes

Organometallics, Vol. 24, No. 11, 2005 2743

Table 9. ³¹P NMR Spectroscopic Data for the Complexes Pd(diphos*)(dba) Generated in Situ and Rates of

2

Oxidative Addition of PhI to Pd(dba) /diphos* Mixtures

Pd(diphos*)(dba)

3

1

P{ H} NMR

(δ, toluene)

formation

reacn time (h)

extent of formation of

Pd(diphos*)(Ph)(I) (%)

diphos*

Me-Duphos

Et-Duphos

i-Pr-Duphos

Me-BPE

63.4 (br), 43.2 (br)^a

57.2 (br), 54.3 (br)

49.9 (br), 47.2 (br)

61.9 (v br), 59.2 (v.br)

37.3 (br), 35.8 (br)

30^b

0 (70 h)

4.5 (40 °C)

0 (70 h)

0 (28 h)

c

40

d

0.5

Me-FerroLANE

Me-DuXantphos

Et-FerroTANE

CyPF-t-Bu

PPF-t-Bu

1

37 (74 h)

e

35.1 (br), 31.9 (br)

23

100 (2 h)

f

45.5 (br), 43.2 (br)

24

56 (51 h)

79.3 (br), 23.0 (br)^g

72 (60 °C)

72 (50 °C)

72

0 (24 h, then 48 h at 60 °C)

100 (72 h, 50 °C)

100 (24 h)

h

80.8 (br), 11.7 (br)

i

BoPhoz

88.2 (br), 8.8 (br)

a

Pd(Me-Duphos)2 (∼15%; see ref 11b) was also observed. 7 h at 40 °C, followed by 23 h at room temperature. ^cA small amount of

b

what is believed to be Pd(i-Pr-Duphos)I2 (see Table 6 and ref 33) was observed, along with signals attributed to Pd(i-Pr-Duphos)(dba).

d

After 30 min the reaction mixture contained 55% Pd(Me-BPE)(dba) and 45% of another material, believed to be Pd(BPE)2 (δ 55.3); after

e

f

2

8 h, it was 66% Pd(Me-BPE)(dba) and 34% Pd(BPE)2._gAfter 23 h, the reaction mixture contained ∼5% Me-DuXantphos. After 24 h,

the reaction mixture contained ∼14% Et-FerroTANE. These peaks were observed initially; later, signals at δ 49.8 and 42.6 were also

h

observed. None of these signals were affected by treatment with PhI. In addition to these signals, peaks at δ 60.9, 47.7, and 29.6 were

i

observed; they were unaffected by treatment with PhI. In addition to these signals, peaks at δ 29.7 and 27.4 were observed; they were

unaffected by treatment with PhI.

mmol) was slurried in toluene (0.5 mL), and a solution of

diphos* (1 equiv) in toluene (1 mL) was added. The reaction

mixture was transferred to an NMR tube and monitored by

Me-Duphos)(Ph)(I) and unreacted Pt((R,R)-Me-Duphos)(trans-

stilbene) were still present. During this process the color

changed from bright yellow to pale yellow.

31

1

P{ H} NMR spectroscopy until free ligand was no longer

The complexes Pd(diphos*)(Ph)(I) were prepared by treat-

ment of Pd(TMEDA)(Ph)(I) or Pd(PPh ) (Ph)(I) with diphos*.

observed. In some cases, the mixture was heated to speed up

the reaction. The tube was then brought back into the

glovebox; in some cases, the solution was filtered through

3

2

Typical procedures are given below, with details for the

analogous compounds being given in the Supporting Informa-

tion.

Celite to remove unreacted Pd(dba)

2

and Pd black. PhI (5 µL,

0

.05 mmol, 1.5 equiv) was then added via microliter syringe,

Pd((R,R)-Me-Duphos)(Ph)(I) (3a). To a slurry of Pd-

PPh ) (Ph)(I) (159.2 mg, 0.191 mmol) in THF (5 mL) in a vial

3 2

31

1

and the reaction was monitored by P{ H} NMR spectroscopy.

Table 6 summarizes the results of these experiments; ad-

ditional spectroscopic data and details are given in Table 9.

Oxidative Addition of PhI to Ni(Me-Duphos)(trans-

stilbene). Ni(Me-Duphos)(trans-stilbene) (38 mg, 0.069 mmol)

was dissolved in toluene (1 mL), and PhI (11.6 µL, 0.10 mmol)

was added via microliter syringe. The solution was then

(

wrapped in aluminum foil was added (R,R)-Me-Duphos (64.1

mg, 0.21 mmol, 1.1 equiv) as a solution in THF (2 mL). Upon

addition the solid dissolved and the reaction mixture changed

color from yellow to red-brown. After it was stirred for 2 h at

room temperature, the reaction mixture was filtered through

Celite, concentrated to ∼0.5 mL, and layered with petroleum

ether. After this mixture was cooled overnight at -30 °C, the

resulting orange oily residue was triturated with petroleum

ether and dried in vacuo to give 85.2 mg (72%) of the desired

compound as a yellow-orange solid. No Pd((R,R)-Me-Duphos)-

31

transferred to an NMR tube and monitored periodically by P-

1

{

H} NMR spectroscopy.

Competition Experiment: Oxidative Addition of PhI

to trans-Stilbene Complexes of Ni(Me-Duphos) and Pd-

Me-Duphos). Ni(Me-Duphos)(trans-stilbene) (17.0 mg, 0.031

3

1

(

I

2

was observed by P NMR.

mmol) and Pd(Me-Duphos)(trans-stilbene) (18.5 mg, 0.031

mmol) were dissolved in toluene (1 mL). PhI (11.2 µL, 0.10

mmol) was then added via microliter syringe, and the solution

was transferred to an NMR tube. The reaction was then

periodically monitored by P{ H} NMR spectroscopy.

A spectrum obtained 5 min after the addition of PhI showed

the presence of Pd(Me-Duphos)(Ph)(I) and Ni(Me-Duphos)-

Slow diffusion of petroleum ether into a THF solution of the

compound yielded a yellow oil which solidified upon trituration

with petroleum ether to yield an analytically pure solid. The

solid was stable when stored at -25 °C in the dark but became

pink at room temperature in the light. In solution, the

compound slowly decomposed to form Pd metal and Pd((R,R)-

3

1

Me-Duphos)I

was obtained by slow evaporation of C

Anal. Calcd for C H IP Pd‚THF: C, 48.73; H, 5.97.

2

. A sample suitable for crystallographic analysis

(

trans-stilbene) (both diastereomers) only. The spectrum re-

mained unchanged on continued monitoring, although after

0 min a small quantity of solid precipitated from the reaction

mixture.

Reaction of Pt((R,R)-Me-Duphos)(trans-stilbene) (Pt-

a) with PhI. To a yellow solution of Pt((R,R)-Me-Duphos)-

trans-stilbene) (30 mg, 0.04 mmol) in toluene (0.5 mL) was

6 6

D .

2

4

33

2

3

Found: C, 49.09; H, 6.13. The presence of solvent was

1

31

1

confirmed by H NMR. P{ H} NMR (C D ): δ 67.8 (d, J )

6

1

6 6

27), 64.7 (d, J ) 27). H NMR (C D ): δ 7.87 (br, 2H, Ar), 7.26-

2

(

7.19 (m, 3H, Ar), 7.10-7.00 (m, 4H, Ar), 4.00-3.92 (m, 1H,

CH), 3.15-3.06 (m, 1H, CH), 2.40-2.32 (m, 1H, CH), 2.19-

3

added PhI (7.9 µL, 0.07 mmol) with a microliter syringe. The

2.05 (m, 2H, CH

19, JHH ) 7, 3H, Me), 1.59-1.32 (m, 3H, CH, CH

2

), 1.96-1.78 (m, 2H, CH

2

), 1.64 (dd, JPH

)

3

reaction mixture was transferred into an NMR tube and

2

), 1.27 (dd,

3

1

3

monitored by P{ H} NMR. No reaction was observed after 1

day at room temperature. After the reaction mixture was

heated to 60 °C for 15 min, oxidative addition of PhI was

observed, yielding a small amount of Pt((R,R)-Me-Duphos)-

J

PH ) 19, 7, 3H, Me), 1.30-1.24 (m, 2H, overlapping with

previous peak, CH

PH ) 14, 15, 6H, 2Me). C{ H} NMR (C D ): δ 159.3 (d, J )

6 6

3

2

), 0.70-0.63 (overlapping dd, JHH ) 7, 7,

3

13

1

J

138, Ar, quat), 144.1 (dd, J ) 44, 35, Ar, quat), 143.4 (dd, J )

33, 26, Ar, quat), 139.9 (br, Ar, CH), 133.9 (d, J ) 14, Ar, CH),

133.4 (d, J ) 15, Ar, CH), 131.9-131.8 (m, Ar, CH), 128.7-

128.3 (m, Ar, CH, obscured by residual solvent peaks), 127.5

(d, J ) 9, Ar, CH), 123.4 (d, J ) 7, Ar, CH), 43.6 (dd, J ) 29,

(

Ph)(I) along with unreacted Pt((R,R)-Me-Duphos)(trans-stil-

bene). After the reaction mixture was heated to 60 °C for 1 h,

some Pt((R,R)-Me-Duphos)I was also observed, along with Pt-

(R,R)-Me-Duphos)(Ph)(I) and unreacted Pt((R,R)-Me-Duphos)-

trans-stilbene). Heating the reaction mixture at 100 °C for

0 min gave more Pt((R,R)-Me-Duphos)I , although Pt((R,R)-

2

(

10, CH), 42.8 (dd, J ) 21, 8, CH), 38.1 (br, CH ), 37.7 (dd, J )

2

21, 10, CH), 36.9 (br m, 2 CH ), 35.7 (m, CH ), 33.7 (dd, J )

2

1

2

2744 Organometallics, Vol. 24, No. 11, 2005

Brunker et al.

2

7, 8, CH), 18.2-18.0 (m, Me), 16.2-16.1 (m, Me), 15.1-15.0

(d, J ) 1, CH

20, CH), 31.7 (d, J ) 29, CH), 25.7 (apparent t, J ) 22, CH

21.2 (dd, J ) 16, 12, CH ), 20.0 (d, J ) 11, Me), 19.0 (d, J ) 8,

Me), 14.6 (d, J ) 1, Me), 13.8 (d, J ) 1, Me).

Pd((S,S)-Me-FerroLANE)(Ph)(I) (3e). Anal. Calcd for

37FeIP Pd: C, 46.41; H, 5.15. Found: C, 46.22; H, 5.07.

2

), 35.6 (d, J ) 3, CH

2

), 35.0 (CH

2

), 33.5 (d, J )

(

1

5

m, Me), 14.8-14.7 (m, Me). IR: 3044, 2922, 2855, 1650, 1622,

556, 1450, 1378, 1244, 1156, 1111, 1056, 1017, 756, 728, 694,

28, 456.

2

),

2

Pd((R,R)-Et-Duphos)(Ph)(I) (3b). Anal. Calcd for C28

41

H -

IP

2

Pd‚C

6

H

6

: C, 54.38; H, 6.31. Found: C, 54.12; H, 6.52. ³¹P-

C

28

H

2

1

31

1

{

H} NMR (C

): δ 7.91 (br, 2H, Ar), 7.27-7.25 (m, 3H, Ar), 7.12-7.11

m, 1H, Ar), 7.06-7.01 (m, 3H, Ar), 3.85-3.78 (m, 1H, CH),

6 6

D

): δ 61.4 (d, J ) 26), 58.5 (d, J ) 26). H NMR

P{ H} NMR (CDCl

3

): δ 41.0 (d, J ) 32), 23.9 (d, J ) 32). H

(

C

6

D

6

NMR (CDCl ): δ 7.41 (apparent t, J ) 8, 1H, Ar), 7.31

3

(apparent t, J ) 8, 1H, Ar), 7.10 (apparent t, J ) 8, 1H, Ar),

7.04 (apparent t, J ) 8, 1H, Ar), 6.81 (apparent t, J ) 7, 1H,

Ar), 4.57 (m, 1H, Cp), 4.53 (m, 1H, Cp), 4.44 (m, 1H, Cp), 4.40

(m, 3H, Cp), 4.21 (m, 1H, Cp), 4.13 (m, 1H, Cp), 3.95-3.87

(m, 1H), 2.79-2.72 (m, 1H), 2.63-2.56 (m, 1H), 2.24-2.10 (m,

2H), 2.00-1.94 (m, 1H), 1.96 (dd, J ) 7, 1, 3H, Me), 1.92 (d, J

) 7, 3H, Me), 1.82-1.74 (m, 1H), 1.65-1.55 (m, 1H), 1.36-

1.11 (m, 3H), 1.10-1.02 (m, 1H), 0.90 (dd, J ) 15, 7, 3H, Me),

3

.02-2.94 (m, 1H, CH), 2.46-2.39 (m, 1H, CH), 2.30-2.18 (m,

H, CH ), 2.13-1.93 (m, 5H, 2 CH , CH), 1.87-1.53 (m, 4H, 2

), 1.37-1.10 (m, 4H, 2 CH ), 1.03-0.93 (m, 2H, CH ), 0.92

overlapping dd, JHH ) 7, 7, 3H, Me), 0.79 (overlapping dd,

2

CH

2

3

(

3

J

HH ) 7, 7, 3H, Me), 0.74 (overlapping dd, JHH ) 7, 7, 3H,

3

13

1

Me), 0.69 (overlapping dd, JHH ) 7, 7, 3H, Me). C{ H} NMR

): δ 158.2 (d, J ) 138, Ar, quat), 144.8 (dd, J ) 52, 33,

Ar, quat), 144.6 (dd, J ) 34, 24, Ar, quat), 140.1 (br, Ar, CH),

6 6

(C D

1

3

1

3

0.51 (dd, J ) 16, 7, 3H, Me). C{ H} NMR (CDCl ): δ 153.5

1

34.0 (d, J ) 15, Ar, CH), 133.2 (d, J ) 16, Ar, CH), 131.1-

31.0 (m, Ar, CH), 130.9 (d, J ) 5, Ar, CH), 127.6 (d, J ) 9,

(dd, J ) 122, 3, Ar quat), 138.1 (apparent t, J ) 3, Ar), 135.8

(d, J ) 5, Ar), 128.4 (d, J ) 9, Ar), 127.8 (d, J ) 8, Ar), 122.7

(Ar), 75.0 (Cp CH), 74.9 (Cp CH), 74.3 (Cp CH), 74.1 (d, J ) 2,

Cp CH), 73.6 (dd, J ) 33, 7, Cp quat), 72.5 (Cp CH), 72.3 (d,

J ) 2, Cp CH), 71.9 (d, J ) 2, Cp CH), 71.6 (d, J ) 2, Cp CH),

70.7 (dd, J ) 21, 3, Cp quat), 38.3 (d, J ) 21, CH), 36.7 (d, J

1

Ar, CH), 123.6 (Ar, CH), 51.3 (d, J ) 27, CH), 50.8 (d, J ) 19,

CH), 44.4 (d, J ) 20, CH), 40.5 (d, J ) 26, CH), 35.2 (d, J ) 2,

CH

6.7 (d, J ) 11, CH

CH ), 24.2 (d, J ) 2, CH

2

), 34.4 (d, J ) 3, CH

), 24.9 (d, J ) 8, CH

), 15.2 (d, J ) 11, Me), 15.0 (d, J )

2

), 34.3 (CH

2

), 32.9 (d, J ) 6, CH

2

),

2

), 24.3 (d, J ) 1,

2

) 28, CH), 36.4 (overlapping, 2 × CH

35.3 (d, J ) 32, CH), 34.7 (d, J ) 22, CH), 34.2 (CH

J ) 13, Me), 21.1 (d, J ) 11, Me), 14.7 (Me), 14.2 (Me).

2

), 36.2 (d, J ) 3, CH

2

),

1

2, Me), 14.3 (d, J ) 8, Me), 14.2 (d, J ) 9, Me).

2

), 21.6 (d,

49

Pd((R,R)-i-Pr-Duphos)(Ph)(I) (3c). Anal. Calcd for C32H -

3

1

IP

2

Pd: C, 52.72; H, 6.78. Found: C, 52.81; H, 6.98. P{ H}

Pd((S,S)-Me-DuXantphos)(Ph)(I) (3f). Anal. Calcd for

1

NMR (CDCl

CDCl ): δ 7.81-7.75 (m, 1H, Ar), 7.69-7.68 (m, 1H, Ar),

.61-7.51 (m, 4H, Ar), 7.09-7.07 (m, 2H, Ar), 6.90-6.87 (m,

H, Ar), 3.46-3.41 (m, 1H, CH), 2.83-2.77 (m, 1H, CH), 2.69-

.60 (m, 1H, CH), 2.44-2.19 (m, 5H, 2 CH , CH), 2.06-1.89

, 2CH), 1.69-1.49 (m, 3H, CH , CH), 1.34-1.23

3

): δ 62.4 (d, J ) 23), 57.0 (d, J ) 23). H NMR

C

33

H

41

P

2

OIPd(CH

2

Cl

2

)

0.5: C, 50.84; H, 5.35. Found: C, 50.64;

1

(

3

H, 5.53. The presence of CH

2

Cl

spectroscopy. P{ H} NMR (CD

(d, J ) 32), 27.1 (d, J ) 32) (B); ratio A:B 3.2:1. P{ H} NMR

2

was confirmed by H NMR

3

1

7

1

2

2 2

Cl , -50 °C): δ 31.7 (A); 36.2

3

1

2

2 2 2 2

(CD Cl , 21 °C): δ 31.3 (br). H NMR (CD Cl , -50 °C): δ 7.71

(

m, 4H, CH

2

(m, 2H, Ar, A), 7.62 (d, J ) 8, 1H, Ar, B), 7.54 (dd, J ) 7, 1,

1H, Ar, B), 7.54-7.32 (overlapping m, 5H, Ar, A), 7.24-7.21

(overlapping m, 2H, Ar, B), 7.20 (d, J ) 7, 2H, Ar, B), 7.15 (t

of d, J ) 7, 1, 1H, Ar, B), 7.07 (t, J ) 7, 2H, Ar, A), 6.96 (t, J

) 7, 1H, Ar, A), 6.92 (t, J ) 8, 1H, Ar, A), 6.79 (m, 1H, Ar, B),

6.69 (t, J ) 7, 1H, Ar, B), 6.61 (br t, J ) 7, 1H, Ar, B), 5.86 (br

m, 1H, Ar, B), 3.48 (m, 1H, B), 2.92 (m, 1H, B), 2.81-2.77 (m,

2H, A), 2.65-2.60 (m, 4H, A), 2.57-2.45 (m, 2H, B), 2.38-

2.27 (m, 1H, B), 2.26-2.13 (m, 2H, A), 2.12-2.06 (m, 2H, A),

2.04-2.01 (m, 1H, B), 1.92 (3H, Xant Me B), 1.83-1.76 (m,

2H, B), 1.70 (6H, Xant Me, A), 1.66-1.62 (overlapping m, 1H,

B), 1.62 (dd, J ) 12, 5, 3H, Me, B), 1.58 (dd, J ) 20, 7, 3H,

Me, B), 1.45 (dd, J ) 19, 7, 3H, Me, B), 1.36 (3H, Xant Me B),

1.29-1.24 (m, 2H, B), 1.23-1.20 (overlapping m, 1H, B), 1.20-

1.14 (m, 6H, Me, A), 1.09-1.01 (m, 2H, A), 0.92 (dd, J ) 10, 7,

Me, 6H, A), 0.27 (dd, J ) 13, 7, 3H, Me, B).

3

m, 1H, CH), 1.12 (d, JHH ) 6, 3H, Me), 1.06 (d, JHH ) 6, 3H,

Me), 0.93 (d, JHH ) 6, 3H, Me), 0.89 (d, JHH ) 6, 3H, Me),

3

0

.86 (d, JHH ) 6, 3H, Me), 0.74-0.71 (two overlapping d, JHH

3

13

1

)

7, 6H, Me), 0.66 (d,

JHH ) 6, 3H, Me). C{ H} NMR

(

CDCl

3

): δ 156.4 (d, J ) 134, Ar, quat), 144.9 (dd, J ) 31, 16,

quat), 144.6 (dd, J ) 32, 5, quat), 134.7 (d, J ) 15, Ar, CH),

33.6 (d, J ) 17, Ar, CH), 131.8 (m, Ar, CH), 131.4 (m, Ar,

1

CH), 127.7 (d, J ) 8, Ar, CH), 123.4 (Ar, CH), 56.7-56.6 (m,

CH), 51.6 (d, J ) 18, CH), 47.2 (d, J ) 33, CH), 32.9 (d, J ) 2,

CH

3

2

)

8

2

), 32.35 (d, J ) 3, CH

0.9 (d, J ) 6, CH ), 30.1 (d, J ) 7, CH), 29.6 (d, J ) 2, CH),

8.6 (CH), 26.9 (d, J ) 8, Me), 26.7 (d, J ) 4, Me), 26.0 (d, J

2 2

), 32.04 (CH ), 32.02 (d, J ) 10, CH),

2

6, Me), 25.1 (d, J ) 6, Me), 22.7 (d, J ) 7, Me), 22.6 (d, J )

, Me), 21.6 (d, J ) 6, Me), 21.5 (d, J ) 7, Me).

Pd((R,R)-Me-BPE)(Ph)(I) (3d). Pd(TMEDA)(Ph)(I) (53

mg, 0.12 mmol) was slurried in THF (1 mL), and a solution of

Complex 3f was also generated in toluene by oxidative

addition of PhI to impure Pd(Me-DuXantphos)(trans-stilbene)

(

R,R)-Me-BPE (32 mg, 0.12 mmol) in THF (1 mL) was added

slowly. All the solid dissolved initially; then a white precipitate

formed. The reaction mixture was stirred for 45 min, and then

all volatiles were removed in vacuo to give a pale orange solid,

which was washed with petroleum ether (3 mL). The residue

or to Pd(dba)

2

/Me-DuXantphos. In the latter experiment, at

room temperature, four broadened peaks were observed in the

31

1

P{ H} NMR spectrum, which sharpened upon cooling to -20

°C. The AB pattern (toluene, -20 °C; δ 30.8, 25.3 (J ) 417))

was consistent with trans-Pd(Me-DuXantphos)(Ph)(I). Removal

was dried and then redissolved in CH

Layering this solution with Et O (12 mL) and storage at -30

C for 1 week yielded a fine white fluffy solid (pure by NMR

2 2

Cl (3 mL) and filtered.

2

of the solvent in vacuo and dissolution of the residue in CD

Cl gave spectra similar to those of an authentic sample

(prepared by the method above) in the same solvent.

2

-

°

2

spectroscopy) as well as some larger yellow crystalline pieces

which were suitable for elemental analysis. Yield: 50 mg

Pd((S,S)-Et-FerroTANE)(Ph)(I) (3g). Anal. Calcd for

(

0.088 mmol, 70%).

Anal. Calcd for C20

C H FeIP Pd: C, 47.87; H, 5.49. Found: C, 48.03; H, 5.58.

3

0

41

2

3

1

H

33

P

2

PdI: C, 42.24; H, 5.85. Found: C,

): δ 72.9 (d, J ) 25), 61.5

): δ 7.41 (t, J ) 7, 2H, Ph), 7.05

P{ H} NMR (CDCl

3

): δ 46.4 (d, J ) 29), 32.8 (d, J ) 29). H

3

1

4

2.16; H, 6.14. P{ H} NMR (CDCl

3

NMR (CDCl ): δ 7.65 (br t, J ) 6, 1H, Ph), 7.13 (br, 2H, Ph)

3

1

(

d, J ) 25). H NMR (CDCl

3

7.03 (br, 1H, Ph), 6.85 (t of d, J ) 7, 1, 1H, Ph), 4.65 (m, 1H,

Cp), 4.62 (m, 1H, Cp), 4.50 (m, 1H, Cp), 4.48 (m, 3H, Cp), 4.35

(m, 1H, Cp), 4.26 (m, 1H, Cp), 4.14 (quintet, J ) 9, 1H), 2.60-

2.52 (m, 2H), 2.47-2.33 (m, 3H), 2.30-2.17 (m, 2H), 2.13-

1.89 (m, 3H), 1.56-1.51 (m, 1H), 1.41 (t, J ) 7, 3H, Me), 1.35

(t, J ) 7, 3H, Me), 1.15-1.10 (m, 2H), 1.07-1.00 (m, 1H), 0.90-

0.82 (m, 1H), 0.79 (t, J ) 7, 3H, Me), 0.44 (t, J ) 7, 3H, Me).

t of d, J ) 8, 3, 2H, Ph), 6.84 (t of d, J ) 8, 1, 1H, Ph), 3.44

m, 1H), 2.32-2.20 (m, 2H), 2.14-1.71 (overlapping m, 8H),

1

.65-1.56 (m, 1H), 1.51 (dd, J ) 18, 7, 3H, Me), 1.46 (partially

obscured m, 2H), 1.41 (dd, J ) 19, 7, 3H, Me), 1.38-1.25 (m,

1

H), 1.22 (dd, J ) 14, 7, 3H, Me), 1.18 (dd, J ) 15, 7, 3H, Me),

13

1

3

.05-0.95 (m, 1H). C{ H} NMR (CDCl ): δ 158.9 (d, J ) 132,

1

3

1

Ph quat), 137.6 (Ph), 127.2 (d, J ) 9, Ph), 122.5 (Ph), 39.2 (d,

J ) 26, CH), 39.1 (d, J ) 19, CH), 36.8 (d, J ) 3, CH ), 36.0

C{ H} NMR (THF-d

8

): δ 155.9 (dd, J ) 127, 5, quat Pd-

2

6 5

C H ), 141.1 (br), 137.4 (br m), 128.1 (d, J ) 9), 123.0, 79.1 (d,

Chiral Palladium(0) trans-Stilbene Complexes

Organometallics, Vol. 24, No. 11, 2005 2745

J ) 2, Cp), 78.9 (d, J ) 2, Cp), 77.9 (Cp), 77.8 (Cp), 75.9 (d, J

Anal. Calcd for C42

H

35

P

2

NiI: C, 64.08; H, 4.48. Found: C,

3

1

)

8, Cp), 75.8 (d, J ) 9, Cp), 73.4 (Cp), 73.1 (Cp), 71.6 (dd, J

23, 6, quat Cp), 70.9 (dd, J ) 16, 2, quat Cp), 42.0 (d, J )

64.13; H, 4.70. P{ H} NMR (C ): δ 25.2, 22.6 (1:1 ratio).

6 6

D

3

1

P{ H} NMR (CDCl

(C ): δ 10.1 (v br), 7.78 (br), 7.45 (d, J ) 7), 7.00 (br), 6.27

(d, J ) 7), 2.5 (v br).

The initial orange-brown solid product formed C D and

3

): δ 24.3, 22.3 (1:5 ratio). H NMR

3

5, CH), 37.8 (d, J ) 15, CH

2

), 37.3 (d, J ) 37, CH), 36.9 (d, J

6 6

D

)

31, CH), 36.2 (d, J ) 30, CH), 35.9 (d, J ) 15, CH

), 27.6 (d, J ) 4, CH ), 26.0 (d, J ) 4, CH

2

), 27.9 (d,

), 25.7 (d,

J ) 6, CH

2

6

1

J ) 5, CH

2

), 15.0 (d, J ) 10, Me), 14.8 (d, J ) 11, Me), 12.4 (d,

CDCl₃solutions of the same color, whose H NMR spectra

contained a mixture of broadened and sharper peaks. An

attempt to dissolve the orange-brown solid in THF give a dark

green solution and a small amount of a gray solid, which was

removed by filtration through Celite. The solution was then

layered with an equal volume of petroleum ether and stored

at -30 °C. After 2 weeks very dark green-black lumps of

crystalline material were isolated and dried in vacuo. This

material was analyzed for C and H as follows: C, 65.43; H,

J ) 12, Me), 12.2 (d, J ) 7, Me).

57

H -

FeP

6

3

PdI(CH

Cl

)

(

1

2

9

H), 4.46 (t, J ) 2, 1H), 4.26 (5H), 3.24 (m, 1H), 2.82 (br, 2H),

.34 (m, 3H), 2.01 (t, J ) 7, 3H), 1.91 (br, 7H), 1.73 (d, J ) 12,

H), 1.65-1.26 (10H), 1.20 (d, J ) 13, 9H). ¹³C{ H} NMR

1

4.98. It dissolved in THF-d

8

to give a brown solution, whose

H NMR spectrum revealed two broad peaks at 9.9 and 5.0

ppm. The same batch of solid dissolved in C to give a green

1

(

3

CDCl ): δ 152.0 (Ar), 134.4 (t, J ) 3, Ar), 129.1 (Ar), 129.0

Ar), 126.8 (Ar), 124.3 (d, J ) 5, Ar), 97.7 (d, J ) 22, Cp), 72.6

Cp), 70.8 (Cp), 69.6 (Cp), 69.1 (d, J ) 8, Cp), 68.6 (d, J ) 5,

6 6

D

1

solution, whose H NMR spectrum contained broad peaks at

9.5, 5.1, and 3.3 ppm as well as two somewhat sharper peaks

that could be assigned to THF (3.6 and 1.4 ppm). This solution

slowly deposited a red solid.

Cp), 38.6 (d, J ) 2), 36.2, 33.8, 33.3, 31.4, 29.9, 28.0-27.6 (m),

2

7.5, 27.1, 26.8, 26.2, 25.9, 18.1 (d, J ) 6).

Pd((R,S)-PPF-t-Bu)(Ph)(I) (3i). ¹H NMR (CD

2

Cl ): δ

8

1

.05-7.98 (m, 2H, Ar), 7.56-7.53 (m, 3H, Ar), 7.36-7.30 (m,

H, Ar), 7.24-7.10 (m, 4H, Ar), 6.80 (br, 1H, Ar), 6.41 (br, 4H,

Ni((R,R)-Me-Duphos)(Ph)(I) (Ni-3a). Method 1. Ni-

(COD) (50 mg, 0.18 mmol) was slurried in hexane (1 mL),

2

and a solution of Me-Duphos (55 mg, 0.18 mmol) in hexane (2

mL) was added. Immediately an orange solution formed. After

15 min of stirring, the mixture was filtered through Celite.

PhI (31 µL, 0.27 mmol) was added to the filtrate by microliter

syringe, and the solution was left to stand for 16 h. The

resulting pale orange precipitate was isolated by decantation,

washed with petroleum ether, and dried in vacuo. On drying

the solid turned oily and became brown. The P{ H} NMR

spectrum of this material revealed Ni((R,R)-Me-Duphos)(Ph)-

(I) as the major product as well as the presence of other

unidentified impurities (see below). Attempts to recrystallize

(

)

3

1

t-Bu). P{ H} NMR (CD

): δ 74.3 (d, J ) 40), 18.9 (d, J )

3

1

this material from ether or CH

and resulted in further decomposition.

Method 2. Ni(PPh

(Ph)(I) (21 mg, 2.7 × 10 mol) was

slurried in toluene (1 mL), and a solution of Me-Duphos (8.5

2 2

Cl /hexanes were unsuccessful

-

5

3 2

)

-

5

mg, 2.7 × 10 mol) was added. The resultant yellow cloudy

solution was transferred to an NMR tube and monitored by

3

1

P{ H} NMR spectroscopy. After 15 min, Ni((R,R)-Me-Du-

(

t, J ) 3, 1H, Cp), 4.31 (t, J ) 3, 1H, Cp, minor), 4.14 (1H,

phos)(Ph)(I) as the major product was observed along with

small amounts of impurity A and another unidentified impu-

Cp), 4.13 (1H, Cp, minor), 3.94 (Cp, 5H, minor), 3.89 (5H, Cp),

2

3

.20 (d, J ) 9, 3H), 2.11 (d, J ) 8, 3H, minor), 1.18 (d, J ) 7,

H, minor), 1.15 (d, J ) 7, 3H). The low intensity of other

rity (δ 68.4), as well as some unreacted Ni(PPh

3

)

2

(Ph)(I).

3

1

P{ H} NMR (C D ): δ 75.0 (d, J ) 26), 68.7 (d, J ) 26).

6

3

1

peaks due to the minor isomer and spectral overlap pre-

vented their assignment. C{ H} NMR (CDCl

Ar), 139.4 (m, Ar), 138.7 (m, Ar), 136.8 (m, Ar), 133.9 (d, J )

1

6 6

Impurities observed: P{ H} NMR (C D ) δ 70.1 (d, J ) 29),

1

3

1

3

): δ 148.7 (m,

67.5 (d, J ) 29) (A); 67.6 (d, J ) 28), 64.9 (d, J ) 28) (B). In a

separate experiment Ni(Me-Duphos)I was observed as the

2

1 1

5

2, Ar), 133.6 (Ar), 133.1 (d, J ) 11, Ar), 132.9 (d, J ) 11, Ar),

32.3 (d, J ) 10, Ar), 132.1 (Ar), 130.1 (d, J ) 11, Ar), 129.9

6 6

only impurity: δ 100.1 (Method 1). H NMR (C D ): δ 8.08

1

(br t, J ) 6, 1H, Ar), 7.69 (br t, J ) 6, 1H, Ar), 7.27-7.11

(overlapping m, 3H, Ar), 7.11-6.99 (m, 3H, Ar), 6.93-6.88 (m,

1H, Ar), 4.23-4.09 (m, 1H), 2.82-2.65 (m, 1H), 2.38-2.24 (m,

1H), 2.14-1.97 (m, 2H), 1.94-1.86 (overlapping m, 1H), 1.79

(dd, J ) 18, 8, 3H, Me), 1.56 (dd, J ) 16, 7, 3H, Me), 1.54-

1.33 (overlapping m, 2H), 1.31-1.20 (m, 1H), 1.14-1.08 (m,

1H), 1.03-0.85 (m, 2H), 0.72 (dd, J ) 7, 1, 3H, Me), 0.67 (d, J

) 7, Me).

(d, J ) 2, Ar), 129.7 (Ar), 129.3 (Ar), 129.1 (Ar), 128.7-128.6

m, Ar), 128.3 (d, J ) 8, Ar), 128.1 (d, J ) 10, Ar), 127.8 (d,

(

J ) 11, Ar), 127.1 (d, J ) 10, Ar), 126.6 (m, Ar), 122.1 (Ar),

4.3 (Cp), 71.0 (Cp), 70.8 (Cp, minor), 70.6 (Cp), 70.2 (Cp), 69.1

d, J ) 4, Cp), 68.0 (d, J ) 6, Cp), 54.3 (dd, J ) 6, 19), 34.3,

5.2.

Ni(PPh

7

(

1

3 2 3 4

) (Ph)(I). Ni(PPh ) (0.94 g, 0.85 mmol) was slur-

ried in toluene (15 mL), and PhI (0.55 mL, 1.00 g, 4.9 mmol)

was added by syringe. On addition, the dark orange solution

became paler and a precipitate was observed after about 15

min. The reaction mixture was stirred for 2 h, and then the

Ni((R,R)-Me-Duphos)(Ph)(Cl). Ni(PPh ) (Ph)(Cl) (202 mg,

3

2

0.29 mmol) was stirred as a slurry in THF (3 mL), and a

solution of (R,R)-Me-Duphos (89 mg, 0.29 mmol) in THF (2

mL) was added dropwise. During the addition the starting

material dissolved and the solution darkened somewhat. The

reaction mixture was stirred for 15 h, and then the orange-

yellow slightly cloudy solution was pumped to dryness in

vacuo. The residue was extracted with toluene (6 mL) and

filtered through Celite to give a clear orange-red solution which

was pumped to dryness. The sticky residue was washed with

orange-brown precipitate was isolated by filtration under N

The solid was washed with Et

to yield 405 mg of product. Petroleum ether (10 mL) was added

2

.

2

O (2 × 5 mL) and dried in vacuo

to the toluene supernatant, and the solution was cooled to -30

°

C. After 5 days a further 100 mg of product was isolated,

washed with petroleum ether (5 mL), and dried in vacuo; this

3

1

product was identical with the initial precipitate by P{ H}

NMR spectroscopy (C ) and was analyzed correctly for Ni-

PPh (Ph)(I). Total yield: 505 mg (0.64 mmol, 75%).

D

6 6

(51) Frenzen, G.; Reim, S.; Sippel, H.; Frauenrath, H. Z. Kristallogr.

New Cryst. Struct. 1999, 214, 121-122.

(

3 2

)

2746 Organometallics, Vol. 24, No. 11, 2005

Brunker et al.

petroleum ether (3 mL) and dried in vacuo. The product was

NaI (240 mg, 1.6 mmol). A white precipitate immediately

formed. The solvent was removed by rotary evaporation. The

white solid was washed with water (3 × 50 mL), filtered under

vacuum, and allowed to dry on the frit. The crystals were

washed with petroleum ether (3 × 2 mL) and dried on the frit,

yielding 260 mg (89%) of white crystals.

then dissolved in CH Cl (4 mL), the solution was filtered, and

2

the filtrate was layered with petroleum ether (15 mL). After

storage at -30 °C for 1 week a small amount of yellow solid

(

2

14 mg) was isolated and shown to be Ni(Me-Duphos)Cl by

31

48

P NMR spectroscopy. The supernatant was pumped to

dryness in vacuo, and the residue was redissolved in toluene

3 mL). This solution was filtered, hexane (3 mL) was added,

2 2

Anal. Calcd for C24H33IP Pt‚0.45H O: C, 40.40; H, 4.79.

(

Found: C, 40.07; H, 4.51. The amount of water was quantified

and the solution was cooled to -30 °C. After 3 days, an orange

1

31

1

by integration of the H NMR spectrum in C

6 6

D . P{ H} NMR

crystalline toluene solvate was isolated and dried in vacuo.

(

C

6

D

6

): δ 63.6 (d, J ) 6, JPt-P ) 1616), 56.8 (d, J ) 6, JPt-P )

3

1

This was shown to be pure by P and H NMR spectroscopy.

Yield: 103 mg (using the stoichiometry given below, 72%).

1

3

2

7

3

1

3

1

6 6

754). H NMR (C D ): δ 7.98-7.86 (t, J ) 12, JPt-H ) 63,

H), 7.33-7.28 (m, 2H), 7.25-7.23 (m, 1H), 7.13-7.10 (m, 1H),

.08-7.04 (m, 2H), 6.99 (t, J ) 8, 1H), 4.01-3.95 (m, 1H),

.29-3.22 (m, 1H), 2.42-2.31 (m, 2H), 2.30-2.15 (m, 1H),

.98-1.85 (m, 2H), 1.62-1.53 (m, 1H), 1.56 (dd, J ) 18, 7,

H, Me), 1.50-1.33 (m, 2H), 1.22 (dd, J ) 18, 7, 3H, Me), 1.10-

Anal. Calcd for C24

33 2 7 8

H P NiCl(C H )0.2: C, 61.50; H, 7.03.

Found: C, 61.56; H, 7.21. The presence of toluene was

1

31

1

confirmed by H NMR spectroscopy in CDCl

3

.

P{ H} NMR

):

1

(

CDCl

3

): δ 69.7 (d, J ) 29), 67.6 (d, J ) 29). H NMR (CDCl

3

δ 7.64-7.61 (m, 1H, Ar), 7.58-7.53 (m, 5H, Ar), 7.07-7.03 (m,

H, Ar), 6.85 (t, J ) 8, 1H, Ar), 3.42-3.37 (m, 1H), 2.99-2.92

m, 1H), 2.54-2.44 (m, 2H), 2.35-2.28 (m, 1H), 2.22-2.14 (m,

13

.02 (m, 1H), 0.86-0.77 (m, 1H), 0.71-0.64 (m, 6H, Me). C-

2

1

{

H} NMR (CDCl

3

): δ 158.9 (dd, J ) 115, 7, quat, Pt-Ph),

(

1

43.6 (2 overlapping dd, J ) 48, 40; J ) 35, 27, quat Ar), 138.7

1

H), 2.06-1.82 (overlapping m, 3H), 1.74 (dd, J ) 18, 7, 3H,

(

broad, Ar), 133.1 (d, J ) 13, Ar), 132.3 (dd, J ) 15, 3, Ar),

31.5-131.1 (m, Ar), 127.6 (d, J ) 7, JPt-C ) 46, Ar), 122.7

Ar), 42.1 (d, J ) 8), 41.9, 37.8, 37.1 (d, J ) 29), 36.6 (d, J )

Me), 1.73 (partially obscured m, 1H), 1.63 (dd, J ) 18, 7, 3H,

Me), 1.66-1.52 (m, 1H), 1.33-1.25 (m, 1H), 0.98 (dd, J ) 7, 1,

1

(

1

3

1

H, Me), 0.95 (dd, J ) 7, 3, 3H, Me). ¹³C{ H} NMR (C

6

D ): δ

4

1

), 36.4, 35.1 (d, J ) 6), 33.2 (d, J ) 36), 17.5 (d, J ) 9, Me),

5.6 (d, J ) 5, Me), 14.7 (d, J ) 1, Me), 14.3 (d, J ) 1, Me).

61.7 (dd, J ) 93, 36, Ni-Ph quat), 145.3 (dd, J ) 45, 34, Ar

quat), 141.8 (m, Ar quat), 132.0 (d, J ) 13, Ar), 131.4 (d, J )

5, Ar), 130.8 (Ar), 130.8 (overlapping m, Ar), 126.6 (Ar), 126.5

Ar), 122.2 (Ar), 43.3 (d, J ) 30, CH), 41.4 (d, J ) 23, CH),

7.5 (CH ), 36.6 (CH ), 36.5 (CH ), 35.2 (d, J ) 5, CH ), 33.7

Pt((R,R)-Me-Duphos)I

Me-Duphos (153.2 mg, 0.5 mmol) in CH

dropwise to a solution of Pt(COD)I (278.5 mg, 0.5 mmol) in

CH Cl (3 mL) to give a pale yellow solution. In the air, the

2

. Method 1. A solution of (R,R)-

1

(

2

Cl (2 mL) was added

2

3

2

(

1

d, J ) 21, CH), 33.5 (d, J ) 34, CH), 17.1 (d, J ) 11, Me),

solvent was removed under reduced pressure and the remain-

5.8 (d, J ) 6, Me), 14.6 (Me), 14.5 (Me).

ing crystals were washed with ethyl ether (3 × 2 mL) and

Pt((R,R)-Me-Duphos)(Ph)(Cl). A solution of (R,R)-Me-

2 2

recrystallized from CH Cl /ether at -25 °C to yield 325 mg

2 2

Duphos (306 mg, 1.0 mmol) in CH Cl (2 mL) was added

(

86%) of pale yellow crystals suitable for X-ray crystallography

Supporting Information).

Method 2. To a stirred slurry of Pt((R,R)-Me-Duphos)Cl

dropwise to a solution of Pt(COD)(Ph)(Cl) (416 mg, 1.0 mmol)

in CH Cl (3 mL) to give a pale yellow solution. In the air, the

2

solvent was removed under reduced pressure and the remain-

ing crystals were washed with petroleum ether (3 × 2 mL)

and recrystallized from THF and petroleum ether at -25 °C

to yield 492 mg (80%) of white crystals.

2

(286.3 mg, 0.5 mmol) in acetone (30 mL) was added NaI (300

mg, 2 mmol). The reaction mixture was refluxed for 5 h, giving

a pale yellow slurry. The solvent was removed by rotary

evaporation. The solid was washed with water (3 × 20 mL)

2

Anal. Calcd. for C24H33ClP Pt: C, 46.95; H, 5.42. Found: C,

3

1

4

)

7.10; H, 5.52. P{ H} NMR (CDCl

3

): δ 67.6 (d, J ) 6, JPt-P

2 2 4

and then dissolved in CH Cl (30 mL). MgSO was added, and

1

1647), 55.1 (d, J ) 6, JPt-P ) 4001). H NMR (CDCl

3

): δ

the mixture was filtered. The solvent was removed by rotary

7

6

2

1

.74-7.72 (m, 1H), 7.62-7.51 (m, 5H), 7.15 (td, J ) 8, 2, 2H),

.93 (t, J ) 8, 1H), 3.40-3.28 (m, 2H), 2.81-2.76 (m, 1H),

.63-2.58 (m, 1H), 2.42-2.27 (m, 2H), 2.14-2.01 (m, 2H),

.93-1.84 (m, 1H), 1.77-1.67 (m, 1H), 1.61-1.55 (m, 2H), 1.49

evaporation. The crystals were washed with ethyl ether (3 ×

2 2

2 mL) and recrystallized from CH Cl /ether at -25 °C to yield

300 mg (80%) of pale yellow crystals.

Anal. Calcd for C H I P Pt: C, 28.63; H, 3.74. Found: C,

1

8

28

2

(

dd, J ) 18, 7, 3H, Me), 1.21 (dd, J ) 18, 7, 3H, Me), 0.96-

28.62; H, 3.68. 31P{

1

H} NMR (CDCl ): δ 71.3 (J

H NMR (CDCl ): δ 7.77-7.65 (m, 4H, Ar), 4.12-3.94 (m, 2H),

3

Pt-P

) 3273).

3

13

1

0

8

)

1

(

)

.83 (m, 6H, Me). C{ H} NMR (CDCl

, quat, Pt-Ph), 144.1 (dd, J ) 49, 38, quat Ar), 141.9 (dd, J

36, 25, quat Ar), 137.6 (J ) 17, Ph), 132.9 (d, J ) 13, Ar),

32.3 (dd, J ) 15, 4, Ar), 131.4-131.2 (m, Ar), 128.8 (Ph), 127.8

d, J ) 7, J ) 45, Ph), 122.9 (Ph), 41.2 (d, J ) 17), 40.9 (d, J

5), 37.3, 36.7 (d, J ) 4), 36.4 (JPt-C ) 42), 35.0 (d, J ) 4),

4.8 (d, J ) 17), 33.2 (d, J ) 38, JPt-C ) 52), 17.3 (d, J ) 9,

3

): δ 163.0 (dd, J ) 118,

2

6

.78-2.16 (m, 8H), 1.94-1.79 (m, 2H), 1.45 (dd, J ) 19, 7,

13

1

H, Me), 0.89 (dd, J ) 17, 7, 6H, Me). C{ H} NMR (CDCl

3

):

δ 141.9 (dd, J ) 47, 29, quat Ar), 132.5 (m, Ar), 132.1 (m, Ar),

4

2.4 (d, J ) 38, JPt-C ) 37), 39.4 (d, J ) 38, JPt-C ) 38), 37.1

Pt-C ) 35), 36.1 (d, J ) 3), 17.2 (m, JPt-C ) 34, Me), 14.3

Me).

(

J

3

Me), 16.1 (d, J ) 4, JPt-C ) 42, Me), 14.30 (d, J ) 16, Me),

1

4.28 (d, J ) 16, Me).

Acknowledgment. We thank the National Science

Foundation for support and Solvias and Eastman for

gifts of chiral phosphines.

Pt((R,R)-Me-Duphos)(Ph)(I) (Pt-3a). Method 1. A solu-

2 2

tion of (R,R)-Me-Duphos (161.4 mg, 0.53 mmol) in CH Cl (2

mL) was added dropwise to a solution of Pt(COD)(Ph)(I) (267

mg, 0.53 mmol) in CH Cl (3 mL) to give a transparent

2

solution. In the air, the solvent was removed under reduced

pressure and the remaining crystals were washed with petro-

leum ether (3 × 2 mL) and recrystallized from THF and

petroleum ether at -25 °C to yield 329 mg (88%) of white

crystals.

Supporting Information Available: Text giving ad-

ditional information on synthetic procedures and tables giving

details of the X-ray crystallographic structure determinations;

crystal data are also given as CIF files. This information is

available free of charge via the Internet at http://acs.org.

Method 2. To a stirred solution of Pt((R,R)-Me-Duphos)-

(

Ph)(Cl) (255 mg, 0.41 mmol) in acetone (30 mL) was added

OM050115H

Article Doi

Chiral palladium(0) trans-stilbene complexes: Synthesis, structure, and oxidative addition of phenyl iodide

DOI: 10.1021/om050115h

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Article abstract of DOI:10.1021/om050115h

Full text of DOI:10.1021/om050115h

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