Formation of stable trans-dihydride ruthenium(II) and 16-electron ruthenium(0) complexes based on phosphinite PONOP pincer ligands. Reactivity toward water and electrophiles

Organometallics 2009, 28, 4791–4806 4791

DOI: 10.1021/om9004077

Formation of Stable trans-Dihydride Ruthenium(II) and 16-Electron

Ruthenium(0) Complexes Based on Phosphinite PONOP Pincer Ligands.

Reactivity toward Water and Electrophiles

Hiyam Salem,^†Linda J. W. Shimon,^‡Yael Diskin-Posner,^‡Gregory Leitus,^‡

Yehoshoa Ben-David,^†and David Milstein*^,†

^†Department of Organic Chemistry and ^‡Unit of Chemical Research Support, The Weizmann Institute of

Science, Rehovot 76100, Israel

Received May 18, 2009

The synthesis of a series of new ruthenium complexes based on the new PONOP ligands 1 and 10

((C₅H₃N-1,3-(OPR₂)₂: 1, R = ⁱPr; 10, R = ^tBu) is presented, including the stable trans-dihydride

complexes (ⁱPr-PONOP)Ru(H)₂(PPh₃) (4) and (^tBu-PONOP)Ru(H)₂(CO) (12) and the stable Ru(0)

complexes (R-PONOP)Ru(CO)₂(6, R=ⁱPr; 15, R=^tBu). A surprisingly stable 16-electron Ru(0)

complex (13) was formed by deprotonation of 12 with KO^tBu. Complex 13 reacts with H₂to afford

the cis-dihydride complex 12a, which isomerized to the trans-dihydride 12. Complex 13 reacted with

CO to afford the saturated Ru(0) complex 15. Reaction of complex 12 with water led to hydrolysis of

the phosphinite PONOP ligand and rearrangement to a dimeric product (14). Reaction of the trans-

dihydride complex 4 with the electrophiles PhCOCl, MeI, and MeOTf led to abstraction of one of the

hydride ligands, forming the monohydride complexes (ⁱPr-PONOP)Ru(H)(PPh₃)(X) (X = Cl (2),

I (8a), OTf (8b)) together with benzaldehyde in the case of 2. Similarly, 12 afforded the monohydride

complexes (^tBu-PONOP)Ru(H)(CO)(X) (X = Cl (11), OTf (17), I (18)). Reaction of the Ru(0)

complexes 6 and 15 with water resulted in hydrolysis of the O-P bond and formation of the

zwitterionic complexes 7 and 16. Treatment of 2 and 11 with MeOTf or MeI resulted in abstraction of

the chloride ligand rather than the hydride, forming complexes 8a,b and 17, 18, respectively.

Additional syntheses of complexes based on ligands 1 and 10 are presented.

Introduction

and ammonia and the direct conversions of alcohols to

acetals catalyzed by a novel acridine-based PNP pincer

complex.⁴

Ruthenium complexes play a major role in catalytic trans-

formations in organic chemistry.¹We have reported recently

reactions catalyzed by PNP and PNN Ru complexes, includ-

ing the dehydrogenation of secondary alcohols to ketones

and H₂, the dehydrogenative coupling of alcohols into esters,

the hydrogenation of esters to alcohols,²and the unprece-

dented reaction of alcohols with amines to form amides with

liberation of H₂.³These reactions are catalyzed by Ru(II)

complexes of the dearomatized PNP (2,6-bis((di-tert-

butylphosphino)methyl)pyridine) and PNN (2-((di-tert-

butylphosphino)methyl)-6-((diethylamino)methyl)pyridine)

pincer ligands. Moreover, we have reported recently the

selective synthesis of primary amines directly from alcohols

trans-Dihydride transition-metal complexes are uncom-

mon, due to the high trans influence of the hydride ligand,

which makes them electronically unfavorable relative to the

cis isomers. They can be stabilized by steric factors, such as

those imposed by bulky ligands.⁵The hydridic character inc-

reases in the presence of high donor ancillary ligands such as

phosphines. The most common trans-dihydride catalysts are

those containing diamine ligands, utilized for hydrogenation

of ketones, first reported by Noyori and co-workers.⁶Few

crystal structures of late-transition-metal trans-dihydride

complexes have been reported, including complexes of Ir,⁷

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*To whom correspondence should be addressed. E-mail: david.

milstein@weizmann.ac.il. Fax: 972-8-9344142.

(1) For recent reviews: (a) Trost, B. M.; Frederiksen, M. U.; Rudd,

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Dalton Trans. 2007, 107. (b) Zhang, J.; Leitus, G.; Ben-David, Y.; Milstein,

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David, Y.; Milstein, D. J. Am. Chem. Soc. 2005, 127, 10840. (d) Zhang, J.;

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790.

r

2009 American Chemical Society

Published on Web 07/30/2009

pubs.acs.org/Organometallics

4792 Organometallics, Vol. 28, No. 16, 2009

Salem et al.

Scheme 1

Ru,⁸and Pt.^5cVery few pincer type trans-dihydride com-

plexes are known, including one example for Ru^2cand three

for Ir,^7,9whereas for early metals only one example is

known.¹⁰

complex and B-C bond activation of the BAr_Fanion

(BAr^-_F=tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) by

electrophilic attack of a POCOP Rh(III) complex. In con-

tinuation of work in our group on PNP-type systems,^2,3we

have now synthesized the analogous phosphinite pyridine-

based ligands R-PONOP (C₅H₃N[OP(R)₂]₂: R=ⁱPr, ^tBu).

Treatment of the complex HRu(Cl)(CO)(PPh₃)₃with the

phosphinite pincer ligand ⁱPr-PONOP (1) in benzene or THF

at 80 °C in a closed vessel for 1 h afforded the complex (ⁱPr-

PONOP)Ru(H)(Cl)(CO) (2; Scheme 1). Complex 2 exhibits

in the ³¹P{¹H} NMR spectrum a singlet at δ 220.18, and in

the ¹H NMR spectrum the hydride appears at δ -15.02 as a

triplet (²J_P,H= 19.8 Hz). Although the ³¹P{¹H} NMR

Herein we report the synthesis and reactivity of new stable

trans-dihydride Ru(II) complexes and stable 16-electron and

18-electron Ru(0) complexes based on the new phosphinite

pincer ligands of the type PONOP. The first crystal structure

of a Ru(0) pincer complex is reported. Saturated zerovalent

ruthenium complexes are common, whereas unsaturated 16-

electron Ru(0) complexes are rare. Short-lived transient

complexes of this type were characterized by flash photolysis

and matrix isolation methods.¹¹To our knowledge, the first

example of an isolable, unsaturated Ru(0) complex is Ru-

(NO)(Cl)(PPh₃)₂.¹²Two other examples of 16-electron Ru-

1

spectrum shows only one singlet, the H NMR spectrum

indicates the presence of an impurity, which gives rise to

peaks in the aromatic region. Removal of the impurity by

recrystallization or by separation by column chromatogra-

phy was not successful. The CO stretch of 2 in the IR

spectrum appears at 1940 cm^-1. Crystals of 2, obtained from

benzene, revealed the expected hexagonal geometry, with the

hydride positioned trans to the chloride (Figure 1; selected

bond lengths and angles are given in Table 1).

In an attempt to prepare a dihydride complex, 2 was

treated with NaHBEt₃; however, no reaction took place

even when excess hydride reagent was used. Chloride

abstraction with AgBF₄led to a mixture of three complexes

which when treated with NaHBEt₃resulted in another

mixture.

13

(0) complexes are Ru(CO)(P^tBu₂Me)₂and its analogue

bearing a chelating phosphine,¹⁴both reported by Caulton.

We report here a PNP-type 16-electron Ru(0) complex.

Results and Discussion

Synthesis of a trans-Dihydride Ru(II) Complex Based on the

ⁱPr-PONOP Ligand. We have previously reported the phos-

phinite pincer type ligands R-POCOP ((C₆H₄(OPR₂)₂: R=

t

ⁱPr, Bu) and their reactions, including selective C-C bond

activation of the ligand {C₆H₃(CH₃)[OP(ⁱPr)₂]₂} with a Rh(I)

(8) (a) Chatwin, S. L.; Diggle, R. A.; Jazzar, R. F. R.; Macgregor,

S. A.; Mahon, M. F.; Whittlesey, M. K. Inorg. Chem. 2003, 42, 7695.

(b) Jazzar, R. F. R.; Bhatia, P. H.; Mahon, M. F.; Whittlesey, M. K.

Organometallics 2003, 22, 670.

(9) Ben-Ari, E.; Leitus, G.; Shimon, L. J.; Milstein, D. J. Am. Chem.

Soc. 2006, 128, 15390.

Heating of ligand 1 and HRu(Cl)(PPh₃)₃in benzene or

THF in a closed vessel at 80 °C for 30 min led to formation of

the complex (ⁱPr-PONOP)Ru(H)(Cl)(PPh₃) (3). Separation

of the generated free PPh₃from complex 3 was accomplished

by silica column chromatography, resulting in a clean 3.

Complex 3 exhibits in the ³¹P{¹H} NMR spectrum a doublet

(10) Choualeb, A.; Lough, A. J.; Gusev, D. G. Organometallics 2007,

26, 3509.

(11) (a) Whittlesey, M. K.; Perutz, R. N.; Virrels, I. G.; George,

M. W. Organometallics 1997, 16, 268. (b) Mawby, R. J.; Perutz, R. N.;

Whittlesey, M. K. Organometallics 1995, 14, 3268. (c) Hall, C.; Jones, W.

D.; Mawby, R. J.; Osman, R.; Perutz, R. N.; Whittlesey, M. K. J. Am. Chem.

Soc. 1992, 114, 7425. (d) Bogdan, P. L.; Weitz, E. J. Am. Chem. Soc. 1989,

111, 3163.

and a triplet at δ 208.11 (²J_P,P=25.6 Hz) and δ 59.15 (²J_P,P

=

25.6 Hz), respectively. The hydride ligand appears in the ¹H

NMR spectrum at δ -16.49 as a quartet (²J_P,H=24.1 Hz).

The CO stretch in the IR spectrum appears at 1941 cm^-1

.

(12) Stiddard, M. H. B.; Townsend, R. E. Chem. Commun. 1969,

1372.

Treatment of 3 with 1 equiv of NaHBEt₃at -35 °C im-

mediately led to clean formation of the trans-dihydride

complex (ⁱPr-PONOP)Ru(H)₂(PPh₃) (4). Complex 4 can

also be obtained by a one-step reaction of RuH₂(PPh₃)₄with

ligand 1 at 75 °C in THF. The difficulty with this route

is separation of the complex from the generated free PPh₃,

(13) (a) Ogasawara, M.; Macgregor, S. A.; Streib, W. E.; Folting, K.;

Eisenstein, O.; Caulton, K. G. J. Am. Chem. Soc. 1995, 117, 8869.

(b) Ogasawara, M.; Macgregor, S. A.; Streib, W. E.; Folting, K.; Eisenstein,

O.; Caulton, K. G. J. Am. Chem. Soc. 1996, 118, 10189.

(14) Gottschalk-Gaudig, T.; Huffman, J. C.; Caulton, K. G.; Grard,

H.; Eisenstein, O. J. Am. Chem. Soc. 1999, 121, 3242.

Article

Organometallics, Vol. 28, No. 16, 2009 4793

˚

Table 1. Selected Bond Lengths (A) and Angles (deg) of

Complex 2

Ru(1)-C(1)

Ru(1)-N(1)

Ru(1)-P(2)

Ru(1)-H(1)

1.851(3)

2.109(2)

2.292(1)

1.72(2)

Ru(1)-P(1)

Ru(1)-Cl(1)

P(2)-O(3)

P(1)-O(2)

2.294(1)

2.504(1)

1.689(2)

1.680(2)

N(1)-Ru(1)-C(1)

P(1)-Ru(1)-P(2)

176.2(1)

159.38(2)

H(1)-Ru(1)-Cl(1)

176.8(7)

˚

Table 2. Selected Bond Lengths (A) and Angles (deg) of

Complex 4

Ru(1)-H(1a)

Ru(1)-N(1)

Ru(1)-P(2)

Ru(1)-H(1b)

1.67(4)

2.098(3)

2.252(1)

1.48(5)

Ru(1)-P(3)

Ru(1)-P(1)

P(2)-O(1)

P(3)-O(2)

2.255(1)

2.259(1)

1.691(2)

1.689(3)

N(1)-Ru(1)-P(1)

P(2)-Ru(1)-P(3)

177.59(8)

158.44(4)

H(1a)-Ru(1)-H(1b)

177(2)

trans-dihydride complexes have been reported recently.^2c,7,8,9,15

Crystal structures of ruthenium trans-dihydride complexes

were reported.⁸trans-Dihydride pincer complexes of Ru^2c

and Ir^7,9were reported, including three crystal structures:

[(^tBuPNP)Ir(CO)(H)₂]PF₆, reported by Goldberg;^7band the

diphenylamine-based pincer complex (ⁱPrPNP)Ir(CO)(H)₂

and the 1,8-diiso-propylphosphinoanthracene-based com-

plex (ⁱPrPCP)Ir(CO)(H)₂, reported by Grubbs.^7a

Reaction of the trans-Dihydride Ru(II) Complex 4 with

Water. Treatment of complex 4 with excess water in benzene

at room temperature resulted in no reaction. Upon heating at

80 °C for 16 h, a new complex was formed which exhibited a

doublet and a triplet in the ³¹P{¹H} NMR spectrum, along

with other compounds (∼50%) which exhibited singlets and

doublets. The ¹H NMR spectrum showed a triplet at δ -16.5

that might be due to a hydrido-hydroxo complex. Separa-

tion of the new complex from the reaction products was not

possible due to similar solubilities.

In an attempt to obtain a hydrido-hydroxo complex,

complex 4 was treated with 1 equiv of O₂, but no immediate

reaction took place. Five days later a number of singlets

appeared in the ³¹P{¹H} NMR spectrum in the δ 105-65

region. When O₂was bubbled through the solution, the

singlets appeared immediately. Similarly, no immediate re-

action of 4 with N₂O was observed, and only after a few days

did a number of undefined compounds as singlets and

doublets appear in the ³¹P{¹H} NMR spectrum.

Figure 1. ORTEP plots of complexes 2 and 4. Hydrogen atoms

(except hydrides) are omitted for clarity. An overlapping (10%)

molecule of complex 2 (on 4) is also omitted for clarity.

Ellipsoids are drawn at the 50% probability level.

due to similar solubilities. Attempts at purification by

chromatography on a silica gel column led to decomposition

of the complex. Complex 4 can be prepared indirectly

by abstraction of the chloride from complex 3, resulting in

(ⁱPr-PONOP)Ru(H)(PPh₃)(BF₄) (5), which when reacted

with 1 equiv of NaHBEt₃afforded complex 4.

Reaction of the trans-Dihydride Ru(II) Complex 4 with CO.

Formation of the ⁱPr-PONOP Ru(0) Complex 6. Treatment

of a benzene solution of complex 4 with 2 equiv of CO at 80 °C

Complex 5 exhibits a doublet and a triplet in the ³¹P{¹H}

NMR spectrum at δ 211.44 (²J_P,P=23.7 Hz) and δ 56.39

(²J_P,P=22.9 Hz), respectively. In the ¹H NMR spectrum the

hydride appears at δ -21.10 as a quartet (²J_P,H=24.7 Hz),

indicating that it is located trans to a weakly coordinating

ligand (counteranion or a solvent molecule). Complex 4

exhibits a doublet and a triplet in the ³¹P{¹H} NMR spec-

trum at δ 234.03 (²J_P,P=27.8 Hz) and δ 77.61 (²J_P,P=27.8

Hz), respectively. The trans-dihydrides appear in the ¹H

NMR spectrum at δ -6.09 as a quartet (²J_P,H=21.2 Hz).

The chemical shift of the hydrides in the ¹H NMR spectrum

is in the range expected for two hydrides trans to each other.

Crystals of complex 4 were grown by slow evaporation of its

pentane solution. The X-ray crystal structure (Figure 1;

selected bond distances and angles are given in Table 2)

of 4 is in line with the spectral data. Several examples of

(15) For recent examples: (a) Williams, D. B.; Kaminsky, W; Mayer,

J. M.; Goldberg, K. I. Chem. Commun. 2008, 4195. (b) Baratta, W.;

Ballico, M.; Del Zotto, A.; Zangrando, E.; Rigo, P. Chem. Eur. J. 2007, 13,

6701. (c) Choualeb, A.; Lough, A. J.; Gusev, D. G. Organometallics 2007,

26, 5224. (d) Choualeb, A.; Lough, A. J.; Gusev, D. G. Organometallics

2007, 26, 3509. (e) Lee, J.; Pink, M.; Caulton, K. G. Organometallics 2006,

25, 802. (f) Abbel, R.; Abdur-Rashid, K.; Faatz, M.; Hadzovic, A.; Lough,

A. J.; Morris, R. H. J. Am. Chem. Soc. 2005, 127, 1870. (g) Burling, S.;

Mahon, M. F.; Paine, B. M.; Whittlesey, M. K.; Williams, J. M. Organome-

tallics 2004, 23, 4537. (h) Mohammad, H. A. Y.; Grimm, J. C.; Eichele, K.;

Mack, H.-G.; Speiser, B.; Novak, F.; Quintanilla, M. G.; Kaska, W. C.; Mayer,

H. A. Organometallics 2002, 21, 5775. (i) Abdur-Rashid, K.; Clapham, S. E.;

Hadzovic, A.; Harvey, J. N.; Lough, A. J.; Morris, R. H. J. Am. Chem. Soc.

2002, 124, 15104. (j) Abdur-Rashid, K.; Faatz, M.; Lough, A. J.; Morris,

R. H. J. Am. Chem. Soc. 2001, 123, 7473. (k) Li, S.; Hall, M. B.

Organometallics 1999, 18, 5682. (l) Nemeh, S.; Flesher, R. J.; Gierling,

K.; Maichle-Moessmer, C.; Mayer, H. A.; Kaska, W. C. Organometallics

1998, 17, 2003. (m) Rybtchinski, B.; Ben-David, Y.; Milstein, D. Organo-

metallics 1997, 16, 3786.

4794 Organometallics, Vol. 28, No. 16, 2009

Salem et al.

Scheme 2

for 7 h led to formation of a new singlet in the ³¹P{¹H}

NMR spectrum at δ 236.55 and a singlet at δ ∼ -5 of free

PPh₃. When complex 4 was treated with only 1 equiv of CO,

only half of 4 was consumed, affording a 1:1 ratio of 4 to the

product, and a corresponding amount of H₂was detected

by GC analysis. The ¹³C{¹H} NMR spectrum exhibited a

triplet at δ 212.59 (²J_P,C=14.8 Hz) for the CO ligands. The

IR spectrum exhibits bands at 1887 and 1846 cm^-1, indicat-

ing two CO ligands, in addition to bands of complex 7 (see

the next section) resulting from a reaction of water traces

with the product upon solvent evaporation. On the basis of

those facts, the proposed structure depicted in Scheme 2 is

of the five-coordinate 18-electron d⁸Ru(0) complex 6.

Complex 6 cannot be separated from the free PPh₃because

of instability upon removal of the solvent under vacuum.

Several examples of Ru(0) complexes have been reported in

the literature.^{11,12,13,14,16,17}

Reaction of the Ru(0) Complex 6 with Water. When com-

plex 6 was treated with 1 equiv or an excess of water at room

temperature, a new complex was formed after 15 min. This

complex exhibits in the ³¹P{¹H} NMR spectrum a doublet of

doublets at δ 203.59 and 143.50 (²J_P,P=246.6 Hz). In the ¹H

NMR spectrum the hydride appears at δ -6.39 as a doublet

of doublets (²J_P,H=27.4 Hz). In the ¹³C{¹H} NMR spectrum

the carbonyl ligands appear at δ 201.58 as a doublet of

doublets (²J_P,C=10.8 Hz) and at δ 198.20 as a triplet (²J_P,C

=

7.5 Hz). We propose that 7 is a P-O cleaved zwitterionic

complex (Scheme 2), on the basis of an X-ray crystal

structure of an analogous complex afforded from ligand

11, as will be shown later (see Reaction of the Ru(0) Complex

15 with Water). The relatively low field chemical shift of the

hydride is in line with its coordination trans to a CO ligand.

1

The hydroxy group was not located in the H NMR spec-

trum. Complex 7 gives rise to bands at 1974 and 1940 cm^-1in

the IR spectrum for the two mutually cis CO ligands.

Complex 7 probably results from protonation of 6 by water,

generating an OH^-ion that attacks the O-P bond, leading

to its cleavage.

Reaction of the trans-Dihydride Ru(II) Complex 4 with

Electrophiles. Complex 4 was treated with several electro-

philes, leading to abstraction of one of its hydrides, indicating

(16) For recent examples where, except for 16h, all include crystal

structures: (a) Field, L. D.; Guest, R. W.; Vuong, K. Q.; Dalgarno, S. J.;

Jensen, P. Inorg. Chem. 2009, 48, 2246. (b) Bolton, P. D.; Grellier, M.;

Vautravers, N.; Vendier, L.; Sabo-Etienne, S. Organometallics 2008, 27,

5088. (c) Kanaya, S.; Imai, Y.; Komine, N.; Hirano, M.; Komiya, S.

Organometallics 2005, 24, 1059. (d) Hill, A. F.; Rae, A. D.; Schultz, M.;

Willis, A. C. Organometallics 2004, 23, 81. (e) Hill, A. F.; Schultz, M.;

Willis, A. C. Organometallics 2004, 23, 5729. (f) Baldwin, R.; Bennett,

M. A.; Hockless, D. C. R.; Pertici, P.; Verrazzani, A.; Uccello Barretta, G.;

Marchetti, F.; Salvadori, P. Dalton Trans. 2002, 4488. (g) Jung, H. M.; Shin,

S. T.; Kim, Y. H.; Kim, M.-J.; Park, J. Organometallics 2001, 20, 3370.

(h) Pertici, P.; Verrazzani, A.; Pitzalis, E.; Caporusso, A. M.; Vitulli, G.

J. Organomet. Chem. 2001, 621, 246. (i) Komiya, S.; Planas, J. G.; Onuki,

K.; Lu, Z.; Hirano, M. Organometallics 2000, 19, 4051.

Figure 2. ORTEP plots of complexes 8a,b. Hydrogen atoms

(except hydrides) are omitted for clarity. Ellipsoids are drawn at

the 50% probability level.

its high hydridic character. On treatment with MeI and

MeOTf, the complexes (ⁱPr-PONOP)Ru(H)(I)(PPh₃) (8a)

and (ⁱPr-PONOP)Ru(H)(OTf)(PPh₃) (8b) were formed, res-

pectively. Complex 8a exhibits in the ³¹P{¹H} NMR spec-

trum a doublet and a triplet at δ 205.72 (²J_P,P=25.3 Hz) and at

δ 59.15 (²J_P,P=25.3 Hz), respectively, and a hydride in the

¹H NMR spectrum at δ -14.34 as a quartet (²J_P,H=24.2 Hz).

Complex 8b exhibits in the ³¹P{¹H} NMR spectrum a

(17) Mitsudo, T.-a.; Ura, Y.; Kondo, T. Proc. Jpn. Acad., Ser. 2007,

83, 65 and references therein.

Article

Organometallics, Vol. 28, No. 16, 2009 4795

˚

Table 3. Selected Bond Lengths (A) and Angles (deg) of

Complex 8a

˚

Table 4. Selected Bond Lengths (A) and Angles (deg) of

Complex 8b

Ru(1)-H(1)

Ru(1)-N(1)

Ru(1)-I(1)

Ru(1)-P(2)

1.53(3)

Ru(1)-P(3)

Ru(1)-P(1)

P(2)-O(1)

P(3)-O(2)

2.2902(7)

2.2928(7)

1.694(2)

1.691(2)

Ru(1)-H(1)

Ru(1)-N(1)

Ru(1)-O(3)

Ru(1)-P(2)

1.52(3)

Ru(1)-P(3)

Ru(1)-P(1)

P(2)-O(1)

P(3)-O(2)

2.2976(4)

2.2969(4)

1.6965(12)

1.6936(12)

2.117(2)

2.8732(3)

2.3151(8)

2.1103(14)

2.3321(12)

2.2992(4)

N(1)-Ru(1)-P(1)

P(2)-Ru(1)-P(3)

178.26(7)

152.29(3)

H(1)-Ru(1)-I(1)

174.6(11)

N(1)-Ru(1)-P(1)

P(2)-Ru(1)-P(3)

173.18(4)

157.052(15)

H(1)-Ru(1)-O(3)

175.9(9)

Scheme 3

doublet and a triplet at δ 210.15 (²J_P,P=23.4 Hz) and at δ

55.79 (²J_P,P=23.4 Hz), respectively, and a hydride in the ¹H

NMR spectrum at δ -24.21 as a quartet (²J_P,H= 22.9 Hz).

Complexes 8a,b were crystallized by pentane diffusion into

a benzene solution of 8a and into a dichloromethane

solution of 8b; the crystal structures are shown in Figure 2,

and selected bond distances and angles are given in Tables 3

and 4.

Upon treatment of complex 4 with 1 equiv of PhCOCl in

benzene and heating for 16 h at 80 °C, complex 2 and

benzaldehyde were formed. Benzaldehyde was detected by

¹H NMR and by GC analysis and quantified (55% yield) by

the addition of the internal standard 2-methoxybenzalde-

hyde. Addition of 3 equiv of CO₂to complex 4 led to

formation of the formate complex 9 (Scheme 3), which

exhibited in the ¹H NMR spectrum a singlet at δ 8.9 of the

formate proton and a quartet at δ -18.77 (²J_P,H=24.0 Hz) of

the hydride ligand. Addition of only 1 equiv was not suffi-

cient for reaction completion. Complex 9 was not clean

1

(70%) and exhibited broad signals in the ³¹P{¹H} and H

NMR spectra.

Synthesis of the trans-Dihydride Ru(II) Complex 12 Based

Figure 3. ORTEP plots of complexes 12 and 14. Hydrogen

atoms (except hydrides) are omitted for clarity. Ellipsoids are

drawn at the 50% probability level.

t

on the Bu-PONOP Ligand. The Bu-substituted PONOP

ligand 10 was prepared for comparison with the ⁱPr-PONOP

system. Reaction of HRu(Cl)(CO)(PPh₃)₃with ligand 10

yielded the complex (^tBu-PONOP)Ru(H)(Cl)(CO) (11), ana-

logous to 2. Unlike 2, complex 11 was obtained cleanly. 11

exhibits in the ³¹P{¹H} NMR spectrum a singlet at δ 226.65,

and consequently lower frequency of the CO stretch (Δν=

∼37 cm^-1). Moreover, the frequency of the CO stretch

decreases on going from 2 to 11, which is in line with the

t

higher basicity of the Bu₂P group of 11. Treatment of

1

complex 11 with 1 equiv of NaHBEt₃resulted in immediate

formation of the corresponding trans-dihydride complex 12

(Scheme 4), unlike the case of complex 4, which does not

react with NaHBEt₃. Complex 12 can also be prepared

directly by the reaction of the precursor H₂Ru(CO)(PPh₃)₃

with ligand 10 at 110 °C, although the reaction is less clean

and separation of the generated free PPh₃is difficult due to

the similar solubilities of it and the product.

and in the H NMR spectrum the hydride appears at δ -

14.07 as a triplet (²J_P,H= 20.7 Hz). In the ¹³C{¹H} NMR

spectrum the carbonyl appears at δ 206.84 as a triplet (²J_P,C

=

10.2 Hz). The IR stretch of CO in 11 appears at 1932 cm^-1, as

compared with 1940 cm^-1for 2. We reported a system

analogous to complexes 2 and 11, based on a PNP pincer

ligand, namely (ⁱPr-PNP)Ru(H)(Cl)(CO),^2cwhich exhibits

the CO stretching frequency at 1903 cm^-1. Thus, the effect of

replacing the CH₂groups of the “arms” by oxygen atoms is

prominent, resulting in much lower π back-bonding

Complex 12 exhibits a singlet at δ 246.60 in the ³¹P{¹H}

NMR spectrum. The hydride ligands appear in the ¹H NMR

4796 Organometallics, Vol. 28, No. 16, 2009

Salem et al.

Scheme 4

Scheme 5

Scheme 6

˚

Table 5. Selected Bond Lengths (A) and Angles (deg) of

Complex 12

Ru(1)-H(1a)

Ru(1)-H(1b)

Ru(1)-N(1)

Ru(1)-P(1)

1.587(16)

1.557(17)

2.1035(7)

2.2816(2)

Ru(1)-P(2)

Ru(1)-C(22)

P(1)-O(1)

P(2)-O(2)

2.2844(2)

1.8516(10)

1.6985(6)

1.6963(6)

N(1)-Ru(1)-C(22)

P(1)-Ru(1)-P(2)

179.17(4)

159.82(1)

H(1a)-Ru(1)-H(1b)

176.7(8)

spectrum at δ -5.03 as a triplet (²J_P,H= 19.5 Hz). The

carbonyl ligand gives rise to a triplet at δ 209.52 in the

¹³C{¹H} NMR spectrum (²J_P,C=11.0 Hz). The IR stretch of

the CO ligand appears at 1918 cm^-1. The system most closely

analogous to 12 is the (PNN)Ru(H)₂(CO) reported by us,^2c

which readily loses H₂, preventing the measurement of its CO

stretching frequency. Crystals of complex 12 suitable for X-

ray diffraction were obtained by slow evaporation of its

benzene solution. The crystal structure of 12 (Figure 3;

selected bond distances and angles are given in Table 5)

exhibits an octahedral arrangement with the two hydrides at

mutually trans positions.

˚

Table 6. Selected Bond Lengths (A) and Angles (deg) of

Complex 14

Ru(1)-H(1)

Ru(1)-H(2)

Ru(1)-N(2)

Ru(2)-N(1)

Ru(1)-O(7)

Ru(1)-P(5)

Ru(2)-P(4)

1.88(7)

1.54(8)

Ru(1)-C(28)

Ru(2)-C(27)

Ru(2)-H(1)

P(4)-O(1)

1.830(5)

1.833(5)

1.60(7)

1.676(4)

1.668(4)

2.104(4)

2.183(3)

Synthesis of a Four-Coordinated Monocarbonyl 16-Elec-

t

tron Ru(0) Complex Based on the Bu-PONOP Ligand.

2.143(4)

2.145(4)

2.284(4)

2.231(1)

2.256(1)

Surprisingly, treatment of complex 11 with 1 equiv of KO^tBu

in benzene or THF leads to a new complex which gives rise to

a broad singlet at δ 233.45 in the ³¹P{¹H} NMR spectrum

(Scheme 5), and no hydrides were observed in the ¹H NMR

spectrum. In the IR spectrum the CO ligand gives rise to a

broad band at 1928 cm^-1. Attempts to crystallize complex 13

were not successful. The structure of the unsaturated Ru(0)

complex 13 is supported by several reactions, as will be

shown later. Complex 13 is unstable under prolonged eva-

poration of the solvent, and as a solid it is stable only for 2

days at room temperature and for 1 week at low temperature.

Reaction of the trans-Dihydride Ru(II) Complex 12 with

Water. When complex 12 was treated with excess water at

room temperature, a color change took place after 24 h of

stirring. The ³¹P{¹H} NMR spectrum showed the formation

of three new singlets, at δ 234.89, 228.85, and 65.78. In the ¹H

NMR spectrum two types of hydrides were present: a doub-

let of doublets at δ -12.21 (²J_P,H=33.8 Hz) and a doublet at

δ -15.17 (²J_P,H=28.9 Hz). The ³¹P{¹H} NMR spectrum of

yellow crystals that precipitated from the mixture revealed

that the two singlets at δ 234.89 and 228.85 belong to one

compound having two different phosphines, complex 14

(Scheme 6 and Figure 3; selected bond distances and angles

are given in Table 6). The reaction of complex 12 with water

led to the cleavage of one of the P-O bonds of the PONOP

ligand and the arrangement of two cleaved moieties to yield

P(5)-O(4)

Ru(2)-O(3)

Ru(2)-O(7)

N(1)-Ru(2)-H(1)

P(5)-Ru(1)-H(1)

P(4)-Ru(2)-O(7)

167(3)

162(2)

174.9(1)

N(2)-Ru(1)-C(28)

O(3)-Ru(2)-C(27)

H(2)-Ru(1)-O(7)

171.7(2)

173.2(2)

163(3)

complex 14. The third singlet at δ 65.78 is for (^tBu)₂POH.

Thinking that excess water is detrimental, we treated com-

plex 12 with only 1 equiv of water, leading to a reaction after

only a few days at room temperature to yield complex 14.

Complex 14 exhibits in the IR spectrum bands at 1946 and

1911cm^-1for the two different carbonyl ligands, and a Ru-H

stretch appears at 2063 cm^-1. H₂was detected by GC

analysis. In D₂O a slower reaction took place, resulting

initially in a mere H/D exchange of the hydride ligands of

12, and after 48 h complex 14 was formed, in addition to

(^tBu)₂POD, which exhibits in the ³¹P{¹H} NMR spectrum a

triplet at δ 62.04.

Upon reaction of 12 and of 13 with water, we noticed the

formation of a new product which converted with time to

complex 14. In the case of 12, the new product formed in

parallel to formation of 14 and disappeared upon consump-

tion of 12, while in the case of 13, this new product formed

first and then converted to 14. It exhibited in the ³¹P{¹H}

NMR spectrum not only a doublet of doublets which

Article

Organometallics, Vol. 28, No. 16, 2009 4797

Scheme 7

resembled that of 7 (and also of 16, as will be shown later) but

also a hydride at a higher field in the ¹H NMR. On the basis

of this, we anticipated that its structure is analogous to that

of 7, with a hydroxyl ligand trans to the hydride (A,

Scheme 6), in line with the shift of the hydride to higher field.

However, only partial spectral data of A could be ob-

1

tained, due to its instability. The ³¹P{¹H} and H NMR

spectra were recorded on a sample prepared in situ in C₆D₆

by reaction of 11 with KO^tBu (stirred for 16 h) followed by

addition of excess water. A exhibits in the ³¹P{¹H} NMR

spectrum a doublet of doublets at δ 154.2 and 212.98 (²J_P,P

=

1

308 Hz). The H NMR spectrum exhibits a hydride at δ

-17.82 (compare to δ -6.39 for 7) as a doublet of doublets

(²J_P,H=20.0 Hz), probably indicative of a hydride trans to a

hydroxy group. It was not possible to assign the hydroxy

groups in the ¹H NMR spectrum because of the presence of

water traces. Apparently, the acidic hydroxy group on the

pyridine ring of A interacts with Ru-OH on another mole-

cule of A, resulting in the elimination of water; attack of the

generated phenoxy group on the metal center of the second

molecule with elimination of two (^tBu)₂POH moieties results

in complex 14.

Treatment of complex 12 with 1 equiv of O₂did not lead to

an immediate reaction. Keeping the reaction mixture under

O₂led to the formation of a mixture which exhibited a

number of singlets in the ³¹P{¹H} NMR spectrum in the δ

160-65 region.

Figure 4. ORTEP plot of complex 15. Hydrogen atoms are

omitted for clarity. Ellipsoidal probability is at 50% level.

Reaction of the Ru(0) Complex 15 with Water. Treatment

of complex 15 with an excess of water at room temperature

resulted in a new complex after 24 h of stirring. It exhibits in

the ³¹P{¹H} NMR spectrum a doublet of doublets at δ 214.01

and 154.59 (²J_P,P=245.9 Hz), similar to the case of complex

7. In the ¹H NMR spectrum a hydride appears at δ -5.98 as a

doublet of doublets (²J_P,H=24.6 Hz), indicative of a hydride

positioned trans to a CO ligand. The carbonyls absorb in

the IR spectrum at 1992 and 1948 cm^-1and the Ru-H at

2061 cm^-1, which gives rise to an intense band compared to

common hydrides, as a result of the strong trans influence of

the trans CO ligand. Crystals of complex 16 revealed an

unanticipated structure of a zwitterionic complex (Scheme 7

and Figure 5; selected bond distances and angles are given in

Table 8), as described before for 7.

Reaction of the trans-Dihydride Ru(II) Complex 12 with

CO. Formation of the ^tBu-PONOP Ru(0) Complex 15.

Treating complex 12 in a benzene or THF solution with 1

equiv of CO at 80 °C for 5 h led to the observation of a new

singlet at δ 247.40 in the ³¹P{¹H} NMR spectrum which is

assigned to the Ru(0) complex 15 (Scheme 7), analogous to

the case for complex 6. Elimination of H₂was confirmed by

GC. The carbonyl ligand of 15 gives rise to three bands in the

IR spectrum at 1938, 1870, and 1828 cm^-1(instead of the

expected two bands), perhaps as a result of solid-state

interactions. Crystals of 15 were grown by the slow evapora-

tion of its pentane solution, and X-ray analysis confirmed the

proposed five-coordinated Ru(0) structure (Figure 4; sele-

cted bond distances and angles are given in Table 7).

Complex 15 can also be prepared by the reaction of

complex 11 with 1 equiv of KO^tBu under an atmosphere of

CO, or (in quantitative yield) by the addition of 1 equiv of

CO to the isolated complex 13 (Scheme 7).

Reaction of the trans-Dihydride Ru(II) Complex 12 with

Electrophiles. Complex 12 was treated with several electro-

philes, leading to the abstraction of one of the hydrides.

When 12 was treated with MeOTf, the complex (^tBu-

PONOP)Ru(H)(OTf)(CO) (17) was formed (Scheme 8).

4798 Organometallics, Vol. 28, No. 16, 2009

Salem et al.

˚

Table 7. Selected Bond Lengths (A) and Angles (deg) of

Complex 15

Scheme 8

Ru(1)-C(1)

Ru(1)-C(2)

Ru(1)-N(1)

Ru(1)-P(1)

1.8605(16)

1.9196(17)

2.1545(12)

2.3150(4)

Ru(1)-P(2)

P(1)-O(3)

P(2)-O(4)

2.3157(4)

1.6857(11)

1.6866(11)

N(1)-Ru(1)-C(2)

C(1)-Ru(1)-C(2)

111.45(6)

111.93(7)

N(1)-Ru(1)-C(1)

P(1)-Ru(1)-P(2)

136.62(6)

154.541(14)

monohydride complexes are inert toward excess electro-

philes. This was previously observed in our work on the

system (ⁱPr-PCP)Ir(H)₂(CO),^15mindicating that in both

cases the hydridic reactivity is a unique property of the

trans-dihydride complexes.

Comments on the Mechanisms of Formation of the trans-

Dihydride Complexes 4 and 12. Treatment of complex 13 with

1 equiv of H₂led to formation of a new complex which

exhibited in the ³¹P{¹H} NMR spectrum a singlet at δ 247.4,

and in the ¹H NMR spectrum two hydrides were observed at

δ -6.41 and -11.46 as broad singlets in a 1:1 ratio, attributed

to the cis-dihydride complex 12a.This complex started im-

mediately to convert at room temperature to the trans-

dihydride complex 12 (Scheme 9), with full conversion

occurring within a few hours. This indicates that the trans-

dihydride complex 12 is thermodynamically more stable at

room temperature than the cis-dihydride complex 12a.

Heating of the trans-dihydride complex 4 at 100 °C in

benzene led to a mixture of undefined compounds, as did

its heating in the solid state at 150 °C for 24 h. On the other

hand, when the bulkier trans-dihydride complex 12 was

heated at 100 °C in benzene, two new singlets were ob-

served in the ³¹P{¹H} NMR spectrum at δ 247.4 (minor)

and 233.4, assigned to the cis-dihydride isomer 12a and

complex 13, in the ratio 12a:12:13=1.2:1:2.7 (at t=18 h).

When the reaction mixture after 48 h of heating was left in a

sealed NMR tube at room temperature for less than 1 h, the

reverse reaction took place and the trans-dihydride com-

plex 12 was recovered (Scheme 10), indicating the presence

of H₂in the system.

Thus, when 12 is heated, it reductively eliminates H₂via

intermediacy of the cis-dihydride 12a, affording the Ru(0)

complex 13 (Scheme 10). Complex 12a, which is detected

when the sample is recorded at room temperature after

heating, is a result of H₂oxidative addition to 13, and it

ultimately isomerizes to the more stable trans isomer.

Reductive elimination of H₂from complex 12 (and from

complex 4 under a CO atmosphere) may involve dissociation

of the CO ligand (or the PPh₃in the case of 4), forming the

cis-dihydride complex, which reductively eliminates H₂and

reassociates the dissociated ligand. Other possible mechan-

isms are CO insertion/elimination, phosphine “arm” disso-

ciation, or a nondissociative trigonal twist.¹⁸

Figure 5. ORTEP plot of complex 16. Hydrogen atoms (except

hydrides) are omitted for clarity. Ellipsoids are drawn at the

50% probability level.

˚

Table 8. Selected Bond Lengths (A) and Angles (deg) of

Complex 16

Ru(1)-H(1)

Ru(1)-C(1)

Ru(1)-C(15)

Ru(1)-N(1)

Ru(1)-P(1)

1.56(2)

Ru(1)-P(2)

P(1)-O(3)

P(2)-O(5)

C(2)-O(2)

2.4154(4)

1.6562(11)

1.5828(11)

1.2822(17)

1.9761(16)

1.8540(15)

2.1978(12)

2.3207(4)

C(1)-Ru(1)-H(1)

P(1)-Ru(1)-P(2)

N(1)-Ru(1)-C(15)

173.0(7)

158.53(1)

169.50(5)

P(1)-Ru(1)-C(1)

C(1)-Ru(1)-C(15)

C(1)-Ru(1)-P(2)

104.62(4)

94.46(6)

95.70(4)

Complex 17 exhibits in the ³¹P{¹H} NMR spectrum a

doublet at δ 205.72 (²J_P,P=25.3 Hz) and a hydride in the

¹H NMR spectrum at δ -14.34 as a quartet (²J_P,H=24.2 Hz).

When 12 was treated with MeI, the complex (^tBu-

PONOP)Ru(H)(I)(CO) was probably formed, exhibiting

the Ru-H in the ¹H NMR spectrum at δ -12.48, compared

with δ -5.03 for 12. This complex was formed in ∼60% yield

in a mixture and was not fully characterized. When 12

was treated with 1 equiv of PhCOCl in benzene and heated

for 5 h at 80 °C, complex 11 and benzaldehyde were formed.

1

Benzaldehyde was detected by H NMR spectroscopy and

by GC analysis and was quantified (57% yield) using

2-methoxybenzaldehyde as an internal standard. The addit-

ion of 1 equiv of CO₂to complex 12 led to no immediate

reaction, and after 24 h a mixture was formed, in addition to

unreacted 12.

It was noticed that using excess electrophiles with 4 and

12 afforded the same products as when 1 equiv was

utilized, suggesting that the hydride ligands of the obtained

(18) Li, S.; Hall, M. B. Organometallics 1999, 18, 5682.

Article

Organometallics, Vol. 28, No. 16, 2009 4799

Scheme 9

Scheme 10

Scheme 11

Scheme 12

appears at δ 205.25 as a triplet (²J_P,C=7.7 Hz). In the IR

spectrum, an intense carbonyl stretch appears at 1917 cm^-1

and another intense (compared to common hydrides), broad

peak which appears at 2009 cm^-1is assigned to the Ru-H

stretch.

Reaction of the Hydrido-Chloride Complexes 3 and 11 with

MeOTf and MeI. Surprisingly, treatment of the hydrido-

chloride complexes 3 and 11 with MeOTf and MeI led to

abstraction of the chloride ligand and not the hydride ligand.

Upon treatment of complex 3 with 1 equiv of MeOTf or MeI

a color change took place, although formation of new

complexes was not evident from the ³¹P{¹H} NMR spec-

trum, due to the chemical shift values being close to those of

the starting complexes. The ¹H NMR spectrum showed the

presence of a hydride ligand, indicating that it was not

attacked by the electrophile. In fact, chloride abstraction

took place, affording complexes 8a,b (Scheme 12), which

have spectral data identical with those of 8a,b obtained from

the reaction of 4 with MeOTf and MeI, respectively. Treat-

ment of complex 11 with MeOTf and MeI led analogously to

abstraction of the chloride ligand, affording complexes 17

and 18 (Scheme 12). The spectral data of 17 obtained from

this reaction are identical with those of the product obtained

from the reaction of 11 with MeOTf. Treatment of 11 with

MeI led to complex 18, although the reaction was very slow,

and reached completion only when a large excess of MeI was

used within 7 days. This could be due to the weaker electro-

philicity of MeI compared to that of MeOTf and the steric

Synthesis of the Unsaturated (^tBu-PONOP)Ru(II) Com-

plex 19 and Its Reaction with CO. The reaction of HRu(Cl)-

(PPh₃)₃with ligand 10 in benzene at 80 °C led to formation of

the complex (^tBu-PONOP)Ru(H)(Cl) (19, Scheme 11), un-

like the reaction of ligand 1 with this complex, which resulted

in the PPh₃complex 3. Coordination of PPh₃to complex 19

does not take place, most probably because of steric hin-

drance. 19 exhibits in the ³¹P{¹H} NMR spectrum a singlet at

δ 212.13. The hydride appears in the ¹H NMR spectrum as a

triplet at a high field of δ -31.15 (²J_P,H=20.2 Hz), indicating

that it is located trans to a vacant coordination site.

Treatment of 19 with 1 equiv of CO led to formation of

complex 20 (Scheme 11) with the CO ligand coordinated

trans to the hydride, which is disfavored electronically due to

the hydride’s high trans influence. The barrier for the con-

version of this kinetic product to the thermodynamic isomer

11 is quite high, as it requires about 48 h of heating at 100 °C

for complete conversion. Complex 20 exhibits in the ³¹P{¹H}

1

t

i

NMR spectrum a singlet at δ 225.07, and in the H NMR

=

effect of the Bu substituents of 11 compared to the Pr

substituents of 3. The fact that complex 18 is obtained easily,

by the reaction of complex 12 with MeI as described earlier,

spectrum the hydride gives rise to a triplet at δ -3.92 (²J_P,H

21.9 Hz). In the ¹³C{¹H} NMR spectrum the carbonyl

4800 Organometallics, Vol. 28, No. 16, 2009

Salem et al.

Scheme 13

Reaction of the trans-dihydride complexes with small elec-

trophiles resulted in the abstraction of one of the hydrides,

the resulting monohydride complexes being inert to excess

electrophiles. Surprisingly, reaction of the hydrido-chloride

complexes 3 and 11 with the electrophiles MeOTf and MeI

led to chloride ligand abstraction rather than the expected

hydride abstraction.

Experimental Section

General Procedures. All experiments with metal complexes

and the phosphinite ligand were carried out under an atmo-

sphere of purified nitrogen in a Vacuum Atmospheres glovebox

equipped with a MO 40-2 inert gas purifier or using standard

Schlenk techniques. All solvents were reagent grade or better.

All non-deuterated solvents were refluxed over sodium/benzo-

phenone ketyl and distilled under an argon atmosphere. Deut-

˚

4 A molecular sieves.

leads us to conclude that the dominant factor is the difficulty

of chloride abstraction by the weaker electrophile. A few

examples of electrophilic attack of MeOTf on a chloride

ligand were reported for the late transition metals Ru, Os,

Pd, and Pt.¹⁹However, in only one of those reported cases

was another ligand present susceptible for attack, apart from

the chloride.^19a

erated solvents were dried over

Commercially available reagents were used as received. RuCl₂-

(PPh₃)₃,²¹HRu(CO)(Cl)(PPh₃)₃,²²H₂Ru(CO)(PPh₃)₃,²³HRu-

24

(Cl)(PPh₃)₃,²³and H₂Ru(PPh₃)₃were prepared according to

literature procedures. ¹H, ¹³C, ³¹P, and ¹⁹F NMR spectra were

recorded at 400, 100, 162, and 376 MHz, respectively, using

a Bruker AMX-400 NMR spectrometer and at 500, 125, and

1

202 MHz, respectively, for H, ¹³C, and ³¹P, using a Bruker

Formation of the Dichloride Complexes 21 and 22. Upon

reaction of ligand 1 with RuCl₂(PPh₃)₃at 80 °C for 1 h, the

trans-dichloride complex 21 was formed (Scheme 13). In

contrast, when the same reaction was carried out with ligand

10 it required no heating and resulted in the dichloride

complex 22 with no coordination of PPh₃(Scheme 13). The

Avance-500 NMR spectrometer. All spectra were recorded at

23 °C unless stated otherwise. NMR measurements were per-

formed in CD₂Cl₂, C₆D₆, and acetone-d₆. ¹H and ¹³C{¹H}

NMR chemical shifts are reported in ppm downfield from

1

tetramethylsilane. H NMR chemical shifts are referenced to

the residual hydrogen signal of the deuterated solvent (7.15 ppm

for benzene, 5.32 ppm for dichloromethane, and 2.04 ppm

for acetone). In ¹³C{¹H} NMR measurements the signals of

deuterated benzene (128.0 ppm), deuterated dichloromethane

(53.8 ppm), and deuterated acetone (205.19 ppm) were used as a

reference. ³¹P NMR chemical shifts are reported in ppm down-

field from H₃PO₄and referenced to an external 85% solution of

phosphoric acid in D₂O. Abbreviations used in the description

of NMR data are as follows: b, broad; s, singlet; d, doublet; t,

triplet; q, quartet; m, multiplet; sept, septet; v, virtual; dist,

distorted.

t

steric factor of the bulkier Bu substituents is probably the

reason for the noncoordination of the PPh₃ligand. Complex

21 exhibits in the ³¹P{¹H} NMR spectrum a doublet and

triplet at δ 194.30 (²J_P,P=24.5 Hz) and δ 38.95 (²J_P,P=23.8

Hz), respectively, whereas complex 22 exhibits in the ³¹P{¹H}

NMR spectrum a singlet at δ 181.16.

A ruthenium PNP based system analogous to complex 21,

(Ph-PNP)Ru(Cl)₂(PPh₃), was characterized crystallographi-

cally, exhibiting the two chloride ligands trans to each other

as expected.²⁰No analogous ruthenium PNP based systems

are known for complex 22.

Synthesis of the Ligand ⁱPr-PONOP ([C₅H₃N-1,3-(OPⁱPr₂)₂], 1).

In a 1 L round-bottom Schlenk flask under nitrogen was added 2,6-

dihydroxypyridine hydrochloride (1.48 g, 10 mmol), N,N,N⁰,N⁰-

tetramethylethylenediamine (20 mmol, 3 mL), and triethylamine

(61 mmol, 8.5 mL) in 60 mL of dry THF. The reaction mixt-

ure was cooled to 0 °C, and a solution of (ⁱPr)₂PCl (22 mmol,

3.35 g) in 30 mL of dry THF was added dropwise. After the

mixture reached room temperature, it was heated with stirring

at 65 °C for 20 h. The reaction mixture was cooled, filtered

under nitrogen over Celite, and dried under vacuum, resulting

in a yellow oil. The residue was distilled under high vacuum

(bp 155 °C at 0.6 mmHg), resulting in a pale yellow oil in

75% (2.6 g) yield in 90% purity. ³¹P{¹H} NMR (C₆D₆): 149.14

(s). ¹H NMR (C₆D₆): 7.01 (t, ³J_H,H=7.8 Hz, 1H, Ar), 6.36 (d,

Summary

The stable trans-dihydride complexes 4 and 12 based on

the new phosphinite PONOP ligands were prepared, and the

first pincer-type stable ruthenium zerovalent complexes

6 and 15 were obtained by the reaction of CO with the

trans-dihydride complexes with release of H₂. One of the

5-coordinated Ru(0) complexes was characterized crystal-

lographically. A 4-coordinated, 16-electron monocarbonyl

Ru(0) complex (13) was also obtained; it reacted with H₂to

form a trans-dihydride complex, and with CO it formed the

5-coordinated bis-carbonyl Ru(0) complex 15. Reaction of

the Ru(0) complexes with water resulted in the activation of

water, accompanied by cleavage of the O-P bond to afford

the zwitterionic systems 7 and 16. Moreover, reaction of

water with the trans-dihydride complex 12 led to ligand

hydrolysis, affording a dimeric product, complex 14.

3

³J_H,H=7.8 Hz, 2H, Ar), 1.97 (sept, J_H,H=7.1 Hz, J_P,H

=

3

1.8 Hz, 4H, P-CH(CH₃)₂), 1.22 (dd, J_H,H=7.0 Hz, J_P,H

10.8 Hz, 12H, P-CH(CH₃)₂), 1.09 (dd, ³J_H,H=7.2 Hz, ³J_P,H

14.9 Hz, 12H, P-CH(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): 163.40

2

(d, J_P,C= 7.0 Hz, Ar), 141.3 (s, Ar), 104.7 (s, Ar), 28.2 (d,

¹J_P,C= 20.9 Hz, P-CH(CH₃)₂), 18.0 (d, J_P,C= 20.6 Hz,

2

P-CH(CH₃)₂), 17.7 (d, ²J_P,C=10.8 Hz, P-CH(CH₃)₂).

(19) (a) Beach, N. J.; Jenkins, H. A.; Spivak, G. J. Organometallics

2003, 22, 5179. (b) Soper, J. D.; Bennett, B. K.; Lovell, S.; Mayer, J. M.

Inorg. Chem. 2001, 40, 1888. (c) Oliver, D. L.; Anderson, G. K. Polyhedron

1992, 11, 2415.

(20) (a) Jia, G.; Lee, H. M.; Williams, I. D. Organometallics 1997, 16,

3941. (b) Barloy, L.; Ku, S. Y.; Osborn, J. A.; De Cian, A.; Fischer, J.

Polyhedron 1997, 16, 291.

(21) Holm, R. Inorg. Synth. 1970, 12, 238.

(22) Ahmad, N.; Levison, J. J.; Robinson, S. D.; Uttley, M. F.;

Wonchoba, E. R.; Parshall, G. W. Inorg. Synth. 1974, 15, 45.

(23) Hallman, P. S.; McGarvey, B. R.; Wilkinson, G. J. Chem. Soc. A

1968, 3143.

(24) Young, R.; Wilkinson, G. Inorg. Synth. 1977, 17, 75.

Article

Reaction of ⁱPr-PONOP (1) with HRu(Cl)(CO)(PPh₃)₃. For-

Organometallics, Vol. 28, No. 16, 2009 4801

J

_P,C=6.8 Hz, P-CH(CH₃)₂), 20.14 (s, P-CH(CH₃)₂), 18.35 (s,

mation of (ⁱPr-PONOP)Ru(H)(Cl)(CO) (2). To a THF slurry

(5 mL) of HRu(CO)(Cl)(PPh₃)₃(100.0 mg, 0.105 mmol) was

added ligand 1 (36.0 mg, 0.105 mmol) in THF (5 mL). The slurry

was heated at 75 °C for 1 h in a closed vessel, resulting in a clear

yellow solution. The solvent was removed under vacuum, and

the residue was washed with pentane (3 ꢀ 5 mL) and dried again

under vacuum, yielding an off-white solid. The yield was not

determined, due to the presence of an impurity. Crystals were

obtained by diffusion of pentane into a THF solution of 2. Anal.

Calcd for C₁₈H₃₂ClNO₃P₂Ru: C, 42.48; H, 6.34. Found: C,

P-CH(CH₃)₂), 17.41 (s, P-CH(CH₃)₂), 16.76 (vt, J_P,C=4.3

Hz, P-CH(CH₃)₂). IR (film): ν_Ru-H2060 cm^-1

.

Reaction of (ⁱPr-PONOP)Ru(H)(Cl)(PPh₃) (3) with NaH-

BEt₃. Formation of (ⁱPr-PONOP)Ru(H)₂(PPh₃) (4). To a cooled

(-35 °C) THF solution (5 mL) of complex 3 (150.0 mg,

0.2 mmol) was added 1 equiv of NaHBEt₃(1.0 M, 0.2 mmol,

200.0 μL) in toluene. The reaction mixture was kept at -35 °C

for 1 h and then warmed to room temperature and stirred for an

additional 1 h. The solution was then filtered through a cotton/

Celite pad, resulting in a yellow solution. The solvent was

removed from the filtrate under vacuum, resulting in a brownish

yellow solid in 99.6% yield (142.6 mg). Anal. Calcd for

C₃₅H₄₈NO₂P₃Ru: C, 59.31; H, 6.83. Found: C, 59.24; H,

1

43.00; H, 6.42. ³¹P{¹H} NMR (CDCl₃): 220.18 (s). H NMR

(CDCl₃): 7.41 (t, ³J_H,H=8.0 Hz, 1H, Ar), 6.43 (d, ³J_H,H=8.0 Hz,

2H, Ar), 3.27 (m, 2H, P-CH(CH₃)₂), 2.47 (m, 2H, P-CH-

2

6.98. ³¹P{¹H} NMR (C₆D₆): 234.03 (d, J_P,P=27.8 Hz), 77.61

3

(CH₃)₂), 1.36 (dd, J_H,H= 8.5 Hz, J_P,H= 18.8 Hz, 6H, P-

(t, ²J_P,P=27.8 Hz). ¹H NMR (C₆D₆): 8.20 (t, ³J_H,H=8.5 Hz, 6H,

Ar, PPh₃), 7.08 (t, ³J_H,H=7.3 Hz, 6H, Ar), 7.0 (d, ³J_H,H=7.1 Hz,

3H, Ar), 6.60 (t, ³J_H,H=7.9 Hz, 1H, Ar), 6.11 (d, ³J_H,H=7.8 Hz,

2H, Ar), 2.13 (m, 4H, P-CH(CH₃)₂), 1.32 (vt, J_P,H=5.3 Hz,

12H, P-CH(CH₃)₂), 1.12 (dd, ³J_H,H=7.5 Hz, ³J_P,H=14.8 Hz,

CH(CH₃)₂), 1.30 (dd, ³J_H,H=6.7 Hz, ³J_P,H=13.0 Hz, 6H, P-

3

CH(CH₃)₂), 1.06 (dd, J_H,H= 8.5 Hz, J_P,H= 18.5 Hz, 6H,

P-CH(CH₃)₂), 0.93 (dd, ³J_H,H=7.1 Hz, ³J_P,H=14.7 Hz, 6H, P-

2

CH(CH₃)₂), -15.02 (t, J_P,H=19.8 Hz, 1H, Ru-H). ¹³C{¹H}

NMR (CDCl₃): 205.32 (t, ²J_P,C=11.0 Hz, Ru-CO), 162.01 (t,

2

³J_P,C=4.0 Hz, Ar), 141.82 (s, Ar), 102.26 (t, ⁴J_P,C=2.0 Hz, Ar),

12H, P-CH(CH₃)₂), -6.09 (vq, J_P,H=21.2 Hz, 2H, Ru-H).

¹³C{¹H} NMR (C₆D₆): 162.89 (t, ²J_P,C=4.1 Hz, Ar), 142.39 (d,

29.38 (vt, J_P,C= 10.0 Hz, P-CH(CH₃)₂), 27.28 (vt, J_P,C

=

2

²J_P,C=37.0 Hz, Ar), 136.33 (s, Ar) 135.44 (d, J_P,C=10.6 Hz,

12.0 Hz, P-CH(CH₃)₂), 18.12 (vt, J_P,C=5.0 Hz, P-CH(CH₃)₂),

17.47 (s, P-CH(CH₃)₂), 17.39 (vt, J_P,C=7.0 Hz, P-CH(CH₃)₂),

15.59 (s, P-CH(CH₃)₂). IR (film): ν_CO1941 cm^-1, ν_Ru-H

2027 cm^-1. X-ray structural analysis of 2: crystal data,

C₁₈H₃₂ClNO₃P₂Ru, yellow prism, 0.3 ꢀ 0.3 ꢀ 0.1 mm³, ortho-

Ar), 128.57 (s, Ar), 126.86 (d, ²J_P,C=8.6 Hz, Ar), 99.32 (br s, Ar),

28.93 (t, ²J_P,C=9.8 Hz, P-CH(CH₃)₂), 18.26 (t, ²J_P,C=3.8 Hz,

P-CH(CH₃)₂), 16.74 (s, P-CH(CH₃)₂). X-ray structural analy-

sis of 4: crystal data, C₃₅H₄₈NO₂P₃Ru, colorless needle, 0.19ꢀ

3

˚

0.08 ꢀ 0.06 mm , monoclinic, P2₁/n, a = 18.1513(12) A, b =

rhombic, Pbca, a=16.303(3) A, b=15.896(3) A, c=18.185(4),

3

˚

19.3219(14) A, c=21.2787(17) A, β=112.711(3)°, from 74 783

reflections, T=120(2) K, V=6884.2(9)A , Z=8, fw=712.17,

from 20° of data, T=120(2) K, V=4713(2) A , Z=8, fw=

3

508.91 g/mol, D_c= 1.435 Mg m^-3, μ = 0.931 mm^-1; data

collection and processing, Nonius KappaCCD diffractometer,

˚

D_c= 1.374 Mg m^-3, μ = 0.634 mm^-1; data collection and

processing, Bruker KappaApexII CCD diffractometer, Mo

˚

Mo KR (λ = 0.710 73 A), graphite monochromator, 51 368

˚

KR (λ=0.710 73 A), graphite monochromator, -22 e h e 20,

reflections collected, 0 e h e 21, 0 e k e 21, 0 e l e 24, frame

scan width 1.0°, scan speed 1° per 140 s, typical peak mosaicity

0.48°, 6185 independent reflections (R_int= 0.039), data pro-

cessed with Denzo-Scalepack software; solution and refinement,

structure solved by direct methods with SHELXS, full-matrix

least-squares refinement based on F²with SHELXL-97, 247

parameters with 0 restraint, final R1=0.0356 (based on F²) for

data with I>2σ(I) and R1=0.0567 on 6185 reflections, good-

ness of fit on F²1.017, largest electron density peak and hole

-23 e k e 23, -26 e l e 26, frame scan width 0.5°, scan speed

1° per 40 s, typical peak mosaicity 0.7°, 74 783 reflections

collected, 13 237 independent reflections (R_int= 0.087), data

processed with APEX2; solution and refinement, structure solved

by direct methods with Bruker AutoStructure, full-matrix least-

squares refinement based on F²with SHELXL-97, 799 para-

meters with 0 restraints, final R1=0.0420 (based on F²) for data

with I > 2σ(I) and R1=0.0872 on 13 237 reflections, goodness

of fit on F²0.993, largest electron density peak and hole 0.727

-3

˚

0.671 and -0.416 e A

.

Reaction of ⁱPr-PONOP (1) with HRu(Cl)(PPh₃)₃. Formation

of (ⁱPr-PONOP)Ru(H)(Cl)(PPh₃) (3). To a THF or benz-

ene slurry (5 mL) of the violet HRu(Cl)(PPh₃)₃(200.0 mg,

0.216 mmol) was added a solution of ligand 1 (74.3 mg,

0.216 mmol) in THF or benzene (2 mL). The reaction mixture

was heated at 80 °C for 30 min, forming a clear yellow-orange

solution, and the solvent was removed under vacuum. The

residue was dissolved in benzene (2 mL), loaded unto a silica

gel column, and eluted with a pentane/benzene mixture (1:1,

20 mL) for removal of the generated free PPh₃and then eluted

with benzene until the complex reached the bottom of the

column, followed by addition of THF was to complete the

elution of complex 3. The solvent was removed under vacuum,

resulting in a yellow solid in 92.3% (149 mg) yield. Anal. Calcd

for C₃₅H₄₇ClNO₂P₃Ru: C, 56.56; H, 6.37. Found: C, 56.86; H,

6.65. ³¹P{¹H} NMR (C₆D₆): 208.11 (d, ²J_P,P=25.6 Hz), 59.15 (t,

²J_P,P=25.6 Hz). ¹H NMR (C₆D₆): 8.29 (t, ³J_H,H=8.6 Hz, 6H,

and -0.554 e A^-3. Note: the crystal contains approximately

10% of molecules with Cl of second hydride.

˚

Reaction of ⁱPr-PONOP (1) with H₂Ru(PPh₃)₄. Formation of

(ⁱPr-PONOP)Ru(H₂)(PPh₃) (4). To a THF slurry (5 mL) of the

yellow H₂Ru(PPh₃)₄(40.0 mg, 0.035 mmol) was added ligand 1

(11.9 mg, 0.035 mmol) in THF (5 mL), leading to a clear yellow

solution. The reaction mixture was heated at 75 °C for 1 h in a

closed vessel with stirring. The color changed to orange, and the

solvent was removed under vacuum. Attempts to remove the

formed PPh₃by extraction with pentane (in which the product is

also quite soluble) or by chromatography through alumina or

silica gel failed.

Reaction of (ⁱPr-PONOP)Ru(H)(Cl)(PPh₃) (3) with AgBF₄.

Formation of (ⁱPr-PONOP)Ru(H)(PPh₃)(BF₄) (5). To a THF

solution (1 mL) of complex 3 (20.0 mg, 0.027 mmol) was added

AgBF₄(5.2 mg, 0.027 mmol) as a solid, leading to the immediate

formation of AgCl and to a slight color change to yellowish

orange. The AgCl was removed by filtration through a cotton/

Celite pad, and the solvent was removed from the filtrate under

vacuum, resulting in an orange solid in 98.6% yield (21.1 mg).

Anal. Calcd for C₃₉H₅₅BF₄NO₃P₃Ru: C, 54.05; H, 6.40. Found:

3

Ar, PPh₃), 7.11 (t, J_H,H=7.3 Hz, 6H, Ar), 7.04 (dd, J_H,H

=

7.2 Hz, 3H, Ar), 6.75 (t, ³J_H,H=8.0 Hz, 1H, Ar), 6.23 (d, ³J_H,H

7.9Hz, 2H, Ar), 2.13(m, 4H, P-CH(CH₃)₂), 1.64(t, ³J_H,H=6.2 Hz,

6H, P-CH(CH₃)₂), 1.18 (dd, ³J_H,H=6.6 Hz, ³J_P,H=13.4 Hz,

6H, P-CH(CH₃)₂), 0.96 (dd, ³J_H,H=5.3 Hz, ³J_P,H=10.9 Hz,

6H, P-CH(CH₃)₂), 0.71 (dd, ³J_H,H=7.9 Hz, ³J_P,H=16.4 Hz,

C, 53.74; H, 6.15. ³¹P{¹H} NMR (acetone-d₆): 211.44 (d, ²J_P,P

=

23.7 Hz), 56.39 (t, ²J_P,P=22.9 Hz). ¹H NMR (acetone-d₆): 7.89

(t, ³J_H,H=8.3 Hz, 1H, Ar), 7.74 (m, 6H, Ar, PPh₃), 7.61 (br d,

³J_H,H=2.8 Hz, 3H, Ar), 7.51 (br d, ³J_H,H=2.8 Hz, 6H, Ar), 6.88

(d, ³J_H,H=8.3 Hz, 2H, Ar), 2.29 (m, 2H, P-CH(CH₃)₂), 1.55 (m,

2

6H, P-CH(CH₃)₂), -16.49 (q, J_P,H=24.1 Hz, 1H, Ru-H).

¹³C{¹H} NMR (C₆D₆): 163.16 (t, ²J_P,C=3.4 Hz, Ar), 141.35 (d,

²J_P,C=38.6 Hz, Ar), 139.23 (s, Ar), 135.32 (d, ²J_P,C=10.0 Hz,

Ar), 129.15 (s, Ar), 127.33 (d, J_P,C= 8.8 Hz, Ar), 100.80

2

3

2H, P-CH(CH₃)₂), 1.13 (dist dd, J_H,H= 6.9 Hz, J_P,H

=

(s, Ar), 32.02 (vt, J_P,C= 11.4 Hz, P-CH(CH₃)₂), 31.30 (vt,

12.4 Hz, 6H, P-CH(CH₃)₂), 1.08 (dist dd, ³J_H,H=6.9 Hz, ³J_P,

4802 Organometallics, Vol. 28, No. 16, 2009

Salem et al.

_H=13.8 Hz, 6H, P-CH(CH₃)₂), 0.73 (m, 12H, P-CH(CH₃)₂),

(film): ν_CO1974 and 1940 cm^-1, ν_Ru-H2048 cm^-1. MS-ESI:

major peak at m/z 490.68 (fragment without one CO ligand) and

minor peak at m/z 520.71 (M^þ, calcd m/z 520.10).

2

-21.10 (vq, J_P1,H= J_P2,H= 24.7 Hz, 1H, Ru-H). ¹³C{¹H}

NMR (C₆D₆): 163.65 (t, ²J_P,C=3.2 Hz, Ar), 143.77 (s, Ar) 139.23

(d, ²J_P,C=41.3 Hz, Ar), 134.59 (d, ²J_P,C=10.4 Hz, Ar), 130.84

(br s, Ar), 128.72 (d, ²J_P,C=9.2 Hz, Ar), 100.88 (s, Ar), 32.09 (vt,

Reaction of (ⁱPr-PONOP)Ru(H₂)(PPh₃) (4) with MeI. For-

mation of (ⁱPr-PONOP)Ru(H)(I)(PPh₃) (8a). To a benzene

solution (1 mL) of complex 4 (20.0 mg, 0.028 mmol) was added

1 equiv (or excess) of MeI (4.0 mg, 0.028 mmol, 1.8 μL), leading

to a slight color change to a brighter brown. The solvent was

removed under vacuum, resulting in a pale yellow solid in 92%

(21.8 mg) yield. Crystals of 8a were obtained by pentane

diffusion into a benzene solution of 8a. Anal. Calcd for C₃₅H₄₇I-

NO₂P₃Ru: C, 50.37; H, 5.68. Found: C, 50.06; H, 5.94. ³¹P{¹H}

NMR (C₆D₆): 205.72 (d, ²J_P,P=25.3 Hz), 59.15 (t, ²J_P,P=25.3

J_P,C= 12.5 Hz, P-CH(CH₃)₂), 30.80 (vt, J_P,C= 7.8 Hz, P-

CH(CH₃)₂), 17.91 (s, P-CH(CH₃)₂), 17.82 (s, P-CH(CH₃)₂),

16.29 (vt, J_P,C=4.3 Hz, P-CH(CH₃)₂), 15.90 (s, P-CH(CH₃)₂).

¹⁹F NMR (Ac-d₆): -151.96 (br s, BF^-₄). IR (film): ν_Ru-H

2013 cm^-1

.

Reaction of (ⁱPr-PONOP)Ru(H)(PPh₃)(BF₄) (5) with NaH-

BEt₃. Formation of (ⁱPr-PONOP)Ru(H)₂(PPh₃) (4). To a cooled

(-35 °C) THF solution (1 mL) of 5 (10.0 mg, 0.013 mmol) was

added 1 equiv of NaHBEt₃(12.5 μL, 0.013 mmol, 1 M solution)

in toluene solution at -35 °C. The reaction mixture was kept at

-35 °C for 1 h and then warmed to room temperature, resulting

in a color change to light brown and formation of a white solid

of NaBF₄, which was removed by filtration through a cotton/

Celite pad. The solvent was removed from the filtrate under

vacuum, resulting in a brown solid in 64% yield (5.7 mg).

Reaction of (ⁱPr-PONOP)Ru(H)₂(PPh₃) (4) with CO. Forma-

tion of (ⁱPr-PONOP)Ru(CO)₂(6). To a benzene solution (1 mL)

of complex 4 (20.0 mg, 0.03 mmol) in a septum-capped vial

(20 mL) was added 2 equiv of CO (1.3 mL, 0.056 mmol) with a

syringe, and the mixture was heated with stirring at 80 °C for 7 h,

resulting in a color change from brownish yellow to red. The

yield could not be determined, as a result of the instability of

complex 6 upon evaporation of solvent (due to reaction with

1

3

Hz). H NMR (C₆D₆): 8.24 (t, J_H,H=7.6 Hz, 6H, Ar, PPh₃),

7.08 (t, ³J_H,H=7.6 Hz, 6H, Ar), 7.01 (d, ³J_H,H=7.6 Hz, 3H, Ar),

6.69 (t, ³J_H,H=7.6 Hz, 1H, Ar), 6.17 (d, ³J_H,H=7.6 Hz, 2H, Ar),

2.47 (m, 2H, P-CH(CH₃)₂), 2.16 (m, 2H, P-CH(CH₃)₂), 1.54

3

(dd, J_H,H=7.6 Hz, J_P,H=14.0 Hz, 6H, P-CH(CH₃)₂), 1.15

(dd, ³J_H,H=7.6 Hz, ³J_P,H=14.0 Hz, 6H, P-CH(CH₃)₂), 0.77 (m,

12H, P-CH(CH₃)₂), -14.34 (vq, ²J_P,H=24.2 Hz, 1H, Ru-H).

=

2

¹³C{¹H} NMR (C₆D₆): 162.82 (br s, Ar), 141.68 (d, J_P,C

2

38.6 Hz, Ar), 139.44 (s, Ar), 135.55 (d, J_P,C=10.0 Hz, Ar),

129.21 (br s, Ar), 127.36 (d, ²J_P,C=8.9 Hz, Ar), 100.81 (s, Ar),

32.60 (vt, J_P,C=8.0 Hz, P-CH(CH₃)₂), 32.19 (vt, J_P,C=11.0 Hz,

P-CH(CH₃)₂), 21.65 (s, P-CH(CH₃)₂), 18.28 (s, P-CH-

(CH₃)₂), 17.37 (vt, J_P,C=5.0 Hz, P-CH(CH₃)₂), 17.07 (s, P-

CH(CH₃)₂). IR (film): ν_Ru-H2085 cm^-1. X-ray structural

analysis of 8a: crystal data, C₃₅H₄₇INO₂P₃Ru, colorless plate,

3

1

water traces). ³¹P{¹H} NMR (C₆D₆): 236.55 (br s). H NMR

˚

0.2 ꢀ 0.1 ꢀ 0.07 mm , monoclinic, P2₁/c, a=10.5766(1) A, b=

o

(C₆D₆): 6.58 (t, ³J_H,H=8.1 Hz, 1H, Ar), 6.09 (d, ³J_H,H=8.1 Hz,

2H, Ar), 2.27 (m, 4H, P-CH(CH₃)₂), 1.21 (m, 24H, P-CH-

(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): 212.59 (t, ²J_P,C=14.8 Hz, Ru-

CO), 161.17 (t, ²J_P,C=3.5 Hz, Ar), 136.51 (s, Ar), 100.36 (s, Ar),

33.06 (vt, J_P,C= 11.4 Hz, P-CH(CH₃)₂), 16.92 (s, P-CH-

(CH₃)₂), 16.45 (vt, J_P,C= 3.8 Hz, P-CH(CH₃)₂). IR (film):

˚

20.0712(2) A, c = 16.7977(1), β = 90.053(1) , from 65 885

3

reflections, T = 120(2) K, V = 3565.90(5) A , Z = 4, fw =

˚

834.62, D_c=1.555 Mg m^-3, μ =1.471 mm^-1; data collection

and processing, Nonius Kappa CCD diffractometer, Mo KR (λ=

˚

0.710 73 A), graphite monochromator, 0 e h e 13, -26 e k e

26, -21 e l e 21, frame scan width 1.0°, scan speed 1° per 8 s,

typical peak mosaicity 0.41°, 65 885 reflections collected, 16 377

independent reflections (R_int= 0.053), data processed with

Denzo-HKL; solution and refinement, structure solved by direct

methods with SHELXS-97, full-matrix least-squares refinement

based on F²with SHELXL-97, 400 parameters with 0 restraints,

final R1=0.0336 (based on F²) for data with I > 2σ(I) and R1=

0.0458 on 8194 reflections, goodness of fit on F²=1.072, largest

ν

_CO1887, 1846 cm^-1

.

Reaction of (ⁱPr-PONOP)Ru(CO)₂(6) with H₂O. Formation

of (ⁱPr-PONOP)Ru(H)(CO)₂(OH) (7). To a benzene solution

(2 mL) of complex 6 (obtained from 40.0 mg of 4, 0.056 mmol)

was added water (50-fold excess, 2.8 mmol, 50.8 μL). The

reaction mixture was stirred at room temperature for 15 min,

resulting in a gradual color change from red to orange and

finally to light yellow. The benzene layer was decanted, and

the water layer was washed twice (1ꢀ2 mL) with benzene. The

combined benzene fractions were dried under vacuum, the

residue was dissolved in pentane and passed through a silica

gel column, and the column was washed carefully with benzene

for removal of free PPh₃until the compound reached the bottom

of the column and started to elute. The complex was then

completely eluted with THF. The solvents were removed under

vacuum, resulting in a yellow oil in 80% (23.6 mg) yield. ³¹P{¹H}

-3

˚

electron density peak and hole 2.025 and -0.842 e A

.

Reaction of (ⁱPr-PONOP)Ru(H₂)(PPh₃) (4) with MeOTf.

Formation of (ⁱPr-PONOP)Ru(H)(OTf)(PPh₃) (8b). To a ben-

zene solution (1 mL) of complex 4 (20.0 mg, 0.028 mmol) was

added a slight excess of MeOTf (1.2 equiv, 5.6 mg, 0.034 mmol).

The color changed to orange, and the product started to

precipitate from the benzene solution. The solvent and excess

of MeOTf were removed under vacuum, resulting in a yellowish

orange powder in 88.4% (21.4 mg) yield. Crystals of 8b were

obtained by pentane diffusion into a CD₂Cl₂solution of 8b.

NMR (C₆D₆): 203.59 (d, ²J_P,P=246.6 Hz) and 143.50 (d, ²J_P,P

=

1

3

246.6 Hz). H NMR (C₆D₆): 6.87 (t, J_H,H=7.7 Hz, 1H, Ar),

6.39 (t, ³J_H,H=8.8 Hz, 1H, Ar), 5.81 (d, ³J_H,H=7.7 Hz, 1H, Ar),

2.02 (m, 2H, P-CH(CH₃)₂), 1.70 (m, 2H, P-CH(CH₃)₂), 1.49

(dd, ⁴J_H,H=7.7 Hz, ³J_P,H=17.6 Hz, 6H, P-CH(CH₃)₂), 1.15 (m,

6H, P-CH(CH₃)₂), 0.94 (m, 6H, P-CH(CH₃)₂), 0.72 (m, 6H,

Anal. Calcd for C₃₆H₄₇F₃NO₅P₃RuS: C, 50.46; H, 5.53. Found:

2

C, 50.58; H, 5.59. ³¹P{¹H} NMR (CD₂Cl₂): 210.15 (d, J_P,P

=

23.4 Hz), 55.79 (t, ²J_P,P=23.4 Hz). ¹H NMR (CD₂Cl₂): 7.61 (t,

³J_H,H=8.9 Hz, 6H, Ar), 7.35 (m, 10H, Ar), 6.64 (d, ³J_H,H=7.6

Hz, 2H, Ar), 2.31 (m, ³J_H,H=7.6 Hz, 2H, P-CH(CH₃)₂), 1.57

(dd, ³J_H,H=7.6 Hz, 2H, P-CH(CH₃)₂), 1.17 (dd, ³J_H,H=7.6 Hz,

³J_P,H= 15.3 Hz, 6H, P-CH(CH₃)₂), 0.99 (m, 12H, P-CH-

2

P-CH(CH₃)₂), -6.39 (dd, J_P,H=27.4 Hz, 1H, Ru-H). ¹³C-

2

{¹H} NMR (C₆D₆): 201.23 (dd, J_P,C= 10.8 Hz, Ru-CO),

=

2

197.91 (t, J_P,C=7.5 Hz, Ru-CO), 171.69 (t, J_P,C=³J_P,C

2.2 Hz, Ar), 161.93 (br s, Ar), 139.80 (s, Ar), 110.61 (s, Ar), 91.84

3

(CH₃)₂), 0.64 (dd, J_H,H= 7.6 Hz, J_P,H= 15.3 Hz, 6H, P-

CH(CH₃)₂), -24.21 (vq, ²J_P₂_,H=22.9 Hz, 1H, Ru-H). ¹³C{¹H}

NMR (CD₂Cl₂): 163.83 (t, J_P,C=3.0 Hz, Ar), 141.83 (s, Ar),

(d, ²J_P,C=5.5 Hz, Ar), 31.81 (dd, ¹J_P,C=10.0 Hz, ³J_P,C=6.0 Hz,

1

3

2

P-CH(CH₃)₂), 31.41 (dd, J_P,C=31.9 Hz, J_P,C=6.2 Hz, P-

140.0 (d, J_P,C=40.9 Hz, Ar), 134.22 (d, J_P,C=11.0 Hz, Ar),

129.97 (br s, Ar), 128.17 (d, ²J_P,C=9.0 Hz, Ar), 101.82 (s, Ar),

31.56 (vt, J_P,C=12.0 Hz, P-CH(CH₃)₂), 30.67 (vt, J_P,C=8.0 Hz,

P-CH(CH₃)₂), 18.24 (s, P-CH(CH₃)₂), 17.61 (s, P-

CH(CH₃)₂), 17.52 (vt, J_P,C=3.0 Hz, P-CH(CH₃)₂), 16.23 (s,

P-CH(CH₃)₂). ¹⁹F NMR (CD₂Cl₂): -79.19 (br s, -CF₃,

^-OTf). IR (film): ν_Ru-H2129 cm^-1. X-ray structural analysis

of 8b: crystal data, C₃₆H₄₇F₃NO₅P₃RuS, yellow chunk,

1

3

CH(CH₃)₂), 30.0 (dd, J_P,C=6.0 Hz, J_P,C=2.1 Hz, P-CH-

(CH₃)₂), 29.74 (dd, ¹J_P,C=6.0 Hz, ³J_P,C=2.1 Hz, P-CH(CH₃)₂),

2

18.16 (d, J_P,C= 2.3 Hz, P-CH(CH₃)₂), 17.67 (br s, P-CH-

=

(CH₃)₂), 17.57 (d, ²J_P,C=5.6 Hz, P-CH(CH₃)₂), 16.0 (d, ²J_P,C

8.7 Hz, P-CH(CH₃)₂), 15.97 (d, ²J_P,C=2.1 Hz, P-CH(CH₃)₂),

15.68 (d, ²J_P,C=1.1 Hz, P-CH(CH₃)₂), 15.29 (d, ²J_P,C=6.4 Hz,

2

P-CH(CH₃)₂), 15.04 (d, J_P,C= 5.0 Hz, P-CH(CH₃)₂). IR

Article

Organometallics, Vol. 28, No. 16, 2009 4803

3

˚

0.15ꢀ0.12ꢀ0.05 mm , monoclinic, P2₁/c, a=12.8189(2) A, b=

resulting in a clear pink solution. The solvent was removed

under vacuum, yielding a pink solid. In order to remove the free

PPh₃, the residue was washed with pentane (5 mL) and the

washings were passed through a silica column. The residue was

dissolved in benzene (1 mL) and passed through the column.

The column was further washed with benzene (5 mL), and

finally the product was eluted with THF. The solvent THF

was removed under vacuum, affording a pink solid in 95.3%

(113 mg) yield. Anal. Calcd for C₂₂H₄₀ClNO₃P₂Ru: C, 46.76; H,

7.14. Found: C, 48.35; H, 7.18. ³¹P{¹H} NMR (C₆D₆): 226.65

(br s). ¹H NMR (C₆D₆): 6.71 (t, ³J_H,H=8.2 Hz, 1H, Ar), 6.09 (d,

³J_H,H=8.2 Hz, 2H, Ar), 1.72 (vt, J_P,H=7.6 Hz, P-C(CH₃)₃),

1.20 (vt, J_P,H=7.3 Hz, P-C(CH₃)₃), -14.07 (t, ²J_P,H=20.7 Hz,

1H, Ru-H). ¹³C{¹H} NMR (C₆D₆): 206.84 (t, ²J_P,C=10.2 Hz,

Ru-CO), 163.20 (t, ²J_P,C=3.9 Hz, Ar), 142.0 (s, Ar), 102.30 (s,

o

˚

11.9722(2) A, c =24.7335(3) A, β= 90.9097(7) , from 12 877

3

reflections, T=100(2) K, V=3795.4(1) A , Z=4, fw=856.79, D_c=

˚

1.499 Mg m^-3, μ=0.652 mm^-1; data collection and processing,

˚

Nonius KappaCCD diffractometer, Mo KR (λ=0.710 73 A),

graphite monochromator, -19 e h e 18, -17 e k e 17, -36 e

l e 36, frame scan width 1.0°, scan speed 1.0° per 60 s, typical

peak mosaicity 0.454°, 47 818 reflections collected, 13 652 in-

dependent reflections (R_int=0.081), data processed with Denzo;

solution and refinement, structure solved by direct methods with

SIR-97, full-matrix least-squares refinement based on F²with

SHELXL-97, 463 parameters with 0 restraints, final R1=0.0357

(based on F²) for data with I > 2σ(I) and R1=0.0485 on 13 108

reflections, goodness of fit on F²1.031, largest electron density

-3

˚

peak and hole 1.232 and -1.281 e A

.

Reaction of (ⁱPr-PONOP)Ru(H₂)(PPh₃) (4) with PhCOCl.

Formation of (ⁱPr-PONOP)Ru(H)(Cl)(PPh₃) (3). To a C₆D₆

solution (0.5 mL) of 4 (20.0 mg, 0.028 mmol) in a septum-

capped NMR tube was added 1 equiv of PhCOCl (4.0 mg,

0.028 mmol), and the reaction mixture was heated at 80 °C for

5 h, leading to a color change to yellow. The ³¹P{¹H} NMR

spectrum of the solution indicated the formation of complex 3.

Ar), 43.18 (t, J_P,C= 3.0 Hz, P-C(CH₃)₃), 40.70 (t, J_P,C

7.6 Hz, P-C(CH₃)₃), 30.50 (vt, J_P,C= 3.8 Hz, P-C(CH₃)₃),

27.85 (vt, J_P,C=2.8 Hz, P-C(CH₃)₃). IR (film): ν_CO1932 cm^-1

_Ru-H2128 cm^-1. MS-ESI: ES^þm/z (11 without the Cl ligand)

530.07 (M^þ, calcd m/z 530.15).

=

1

,

ν

Reaction of (^tBu-PONOP)Ru(H)(Cl)(CO) (11) with NaH-

BEt₃. Formation of (^tBu-PONOP)Ru(H)₂(CO) (12). To a THF

solution (1 mL) of complex 11 (40 mg, 0.071 mmol) was added

1 equiv of NaHBEt₃in toluene solution (1 M solution,

0.071 mmol, 71 μL) at -35 °C, and the mixture was then stirred

at room temperature for 30 min, leading to a color change from

pinkish red to orange. The solvent was removed under vacuum,

the residue was extracted with benzene, and the extract was

filtered through a cotton/Celite pad. The solvent was removed

from the filtrate under vacuum, resulting in an orange solid in

95.7% (36 mg) yield. Anal. Calcd for C₂₂H₄₁NO₃P₂Ru: C,

1

The formation of benzaldehyde was detected by H NMR. Its

quantification was performed by the addition of 2-methoxyben-

zaldehyde as an internal standard, indicating 55% yield, which

was confirmed by GC analysis.

Reaction of (ⁱPr-PONOP)Ru(H)(Cl)(PPh₃) (3) with MeI.

Formation of (ⁱPr-PONOP)Ru(H)(I)(PPh₃) (8a). To a benzene

solution (1 mL) of 3 (15.5 mg, 0.021 mmol) was added MeI

(3.0 mg, 0.021 mmol, 1.29 μL). The reaction mixture was left at

room temperature for 16 h for reaction completion, after which

the product partially precipitated. The solvent was removed

under vacuum, resulting in a pale yellow powder in 93.6%

(16.3 mg) yield. Anal. Calcd for C₃₅H₄₇INO₂P₃Ru: C, 50.37; H,

5.68. Found: C, 50.47; H, 5.84.

49.80; H, 7.79. Found: C, 50.15; H, 7.67. ³¹P{¹H} NMR

3

(C₆D₆): 246.60 (br s). ¹H NMR (C₆D₆): 6.58 (t, J_H,H

8.0 Hz, 1H, Ar), 6.15 (d, J_H,H= 8.2 Hz, 2H, Ar), 1.51 (vt,

=

3

J

_P,H=7.1 Hz, 36H, P-C(CH₃)₃), -5.03 (t, ²J_P,H=19.5 Hz, 2H,

Reaction of (ⁱPr-PONOP)Ru(H)(Cl)(PPh₃) (3) with MeOTf.

Formation of (ⁱPr-PONOP)Ru(H)(OTf)(PPh₃) (8b). To a ben-

zene solution (1 mL) of 3 (20.0 mg, 0.027 mmol) was added a

slight excess of MeOTf (1.2 equiv, 0.032 mmol, 5.3 mg). The

reaction mixture was kept at room temperature for 16 h for

reaction completion. The solvent was removed under vacuum,

resulting in a yellow powder in 97.8% (21.9 mg) yield. Anal.

Calcd for C₃₆H₄₇F₃NO₅P₃RuS: C, 50.46; H, 5.53. Found: C,

49.46; H, 5.58.

Ru-H). ¹³C{¹H} NMR (C₆D₆): 209.52 (t, ²J_P,C=11.0 Hz, Ru-

CO), 162.39 (t, ³J_P,C=4.5 Hz, Ar), 138.86 (s, Ar), 100.77 (s, Ar),

39.54 (vt, J_P,C=6.5 Hz, P-C(CH₃)₃), 28.59 (vt, J_P,C=4.0 Hz, P-

C(CH₃)₃). IR (film): ν_CO1918 cm^-1. X-ray structural analysis of

12: crystal data, C₂₂H₄₁NO₃P₂Ru, red chunk, 0.18 ꢀ 0.15 ꢀ

3

˚

0.02 mm , monoclinic, P2₁/n, a=14.8727(6) A, b=13.0273(6)

o

˚

A, c=14.8764(6) A, β=119.649(2) , from 48 905 reflections, T=

3

100(2) K, V=2504.9(2) A , Z=4, fw=530.57, D_c=1.407 Mgm

-3

˚

,

μ = 0.775 mm^-1, data collection and processing, Bruker

Synthesis of the Ligand ^tBu-PONOP, [1,3-C₅H₃N(OP^tBu₂)₂]

(10). In a 1 L round-bottom Schlenk flask under nitrogen was

added 2,6-dihydroxypyridine hydrochloride (1.47 g, 10 mmol),

N,N,N⁰,N⁰-tetramethylethylenediamine (20 mmol, 3 mL), and

triethylamine (61 mmol, 8.5 mL) in 60 mL of dry THF. The

reaction mixture was cooled to 0 °C, and a solution of (^tBu)₂PCl

(3.97 g, 22 mmol) in 30 mL of dry THF was added to it dropwise.

After the mixture reached room temperature, it was heated with

stirring at 65 °C for 20 h. The reaction mixture was cooled to

room temperature, filtered under nitrogen over Celite, and dried

under vacuum, resulting in a yellow oil that solidified upon

evaporation of the solvent. The residue was distilled under high

vacuum (bp 175-180 °C at 0.2 mmHg), resulting in a pale yellow

oil in 75% (3.0 g) yield in 90% purity. The oil gradually solidified

to a white solid after distillation. Anal. Calcd for C₂₁H₃₉NO₂P₂:

C, 63.14; H, 9.84. Found: C, 62.31; H, 9.84. ³¹P{¹H} NMR

(C₆D₆): 157.49 (s). ¹H NMR (C₆D₆): 7.11 (t, ³J_H,H=7.5 Hz, 1H,

Ar), 6.46 (d, ³J_H,H=7.7 Hz, 2H, Ar), 1.18 (d, ³J_P,H=11.4 Hz,

36H, P-C(CH₃)₃). ¹³C NMR (C₆D₆): 163.16 (d, ²J_P,C=9.3 Hz,

KappaApexII CCD diffractometer, Mo KR (λ=0.710 73 A),

˚

graphite monochromator, -24 e h e 24, -19 e k e 21, -24 e

l e 24, frame scan width 0.5°, scan speed 1° per 20 s, typical peak

mosaicity 0.68°, 47 861 reflections collected, 12 685 indepen-

dent reflections (R_int=0.0302). The data were processed with

SAINT, solution and refinement, structure solved by direct

methods with Bruker AutoStructure, full-matrix least-squares

refinement based on F²with SHELXL-97, 282 parameters with

0 restraints, final R1 = 0.0218 (based on F²) for data with

I > 2σ(I) and R1=0.0281 on 12 259 reflections, goodness of

fit on F²=1.020, largest electron density peak and hole 0.760 and

-3

˚

-0.511 e A

.

t

Reaction of H₂Ru(CO)(PPh₃)₃with Bu-PONOP (10). For-

mation of (^tBu-PONOP)Ru(H)₂(CO) (12). To a benzene solu-

tion (4 mL) of H₂Ru(CO)(PPh₃)₃(40.0 mg, 0.04 mmol) was

added ligand 10 (17.4 mg, 0.04 mmol) as a solid. The reaction

mixture was heated at 100 °C in a closed vessel for 18 h, resulting

in a color change to light brown. This route for the preparation

of 12 resulted in a less clean product, and the separation of the

generated free PPh₃was not possible due to the similarity of its

solubility with that of 12.

Ar), 141.33 (s, Ar), 104.03 (d, ²J_P,C=4.3 Hz, Ar), 35.57 (d, ¹J_P,C

=

28.8 Hz, P-C(CH₃)₃), 27.75 (d, ²J_P,C=16.3 Hz, P-C(CH₃)₃).

Reaction of ^tBu-PONOP (10) with HRu(Cl)(CO)(PPh₃)₃.

Formation of (^tBu-PONOP)Ru(H)(Cl)(CO) (11). To a benzene

slurry (5 mL) of HRu(Cl)(CO)(PPh₃)₃(200.0 mg, 0.21 mmol)

was added ligand 10 (83.9 mg, 0.21 mmol) as a solid. The

reaction mixture was heated at 100 °C for 8 h in a closed vessel,

Reaction of (^tBu-PONOP)Ru(H)(Cl)(CO) (11) with KO^tBu.

Formation of (^tBu-PONOP)Ru(CO) (13). To a THF or benzene

solution (1 mL) of complex 11 (20.0 mg, 0.035 mmol) was added

1.1 equiv of KO^tBu (4.4 mg, 0.039 mmol) as a solid, leading to an

immediate color change to brown. The reaction mixture was

4804 Organometallics, Vol. 28, No. 16, 2009

Salem et al.

stirred for 16 h when utilizing benzene and for 1 h for THF. The

solvent was removed under vacuum, the residue was extracted

with benzene (when using benzene the solution was filtered with

no prior solvent removal), and the extract was filtered through a

cotton/Celite pad. The solvent was removed from the filtrate,

resulting in a brown solid in 97.3% (18.2 mg) yield. ³¹P{¹H}

screw-capped vial (20 mL) was added 1 equiv of CO (2.75 mL,

0.122 mmol) with a syringe, and the reaction mixture was stirred

at 80 °C for 5 h, leading to a color change from orange to violet.

The solvent was removed under vacuum, resulting in an orange

powder in 89.3% (60.9 mg) yield. Anal. Calcd for C₂₃H₃₉NO₄-

P₂Ru: C, 49.63; H, 7.06. Found: C, 49.79; H, 7.09. ³¹P{¹H}

NMR (C₆D₆): 233.45 (br s). ¹H NMR (C₆D₆): 6.71 (t, ³J_H,H

8.0 Hz, 1H, Ar), 6.14 (d, ³J_H,H=8.1 Hz, 2H, Ar), 1.43 (vt, J_P,H

=

NMR (C₆D₆): 247.48 (br s). ¹H NMR (C₆D₆): 6.57 (t, ³J_H,H

8.0 Hz, 1H, Ar), 6.04 (d, ³J_H,H=7.9 Hz, 2H, Ar), 1.39 (vt, J_P,H

=

6.9 Hz, 36H, P-C(CH₃)₃). ¹³C{¹H} NMR (C₆D₆): 216.96 (t,

²J_P,C=12.9 Hz, Ru-CO), 165.89 (t, ³J_P,C=6.0 Hz, Ar), 139.25

(s, Ar), 100.65 (br s, Ar), 40.52 (vt, J_P,C=4.0 Hz, P-C(CH₃)₃),

7.2 Hz, 36H, P-C(CH₃)₃). ¹³C{¹H} NMR (C₆D₆): 215.29 (t,

²J_P,C=13.0 Hz, Ru-CO), 161.19 (t, ³J_P,C=3.2 Hz, Ar), 136.13

(s, Ar), 100.50 (br s, Ar), 41.63 (vt, J_P,C=6.0 Hz, P-C(CH₃)₃),

28.01 (vt, J_P,C= 3.7 Hz, P-C(CH₃)₃). IR (film): ν_CO1937.7,

1870.2, and 1828 cm^-1. X-ray structural analysis of 15: crystal

data, C₁₈₃H₃₁₂N₈ClO₃₁P₁₆Ru₈, red prism, 0.5ꢀ0.5ꢀ0.03 mm³,

28.66 (vt, J_P,C=4.7 Hz, P-C(CH₃)₃. IR (film): ν_CO1928 cm ^-1

MS-ESI: m/z 530.07 (M^þ, calcd m/z 529.14).

.

Reaction of (^tBu-PONOP)Ru(H)₂(CO) (12) with Excess H₂O.

Formation of the Complex (^tBu-PONOH)Ru(CO)(μ-H)(μ-OH)-

(ONOP-^tBu)Ru(H)(CO) (14). To a benzene solution (2 mL) of

complex 12 (20.0 mg, 0.038 mmol) was added an excess of H₂O

(50-fold, 0.03 mL, 1.88 mmol), and the mixture was stirred for 24

h at room temperature, resulting in a color change from orange

to brown. The stirring was stopped, the benzene layer was

decanted, and the aqueous layer was washed with benzene (2ꢀ

1 mL). The solvent was removed from the combined benzene

fractions under vacuum, resulting in a brown solid. The residue

was dissolved in benzene and passed through a silica gel column,

the column was washed with benzene (5 mL), the complex was

eluted with a benzene and THF mixture (benzene:THF=10:1),

and finally the cleaved moiety (^tBu)₂POH was eluted with THF.

The benzene/THF fraction was dried under vacuum, resulting in

a yellow oil in 81.8% (12.1 mg) yield. Anal. Calcd for

C₂₈H₄₆N₂O₇P₂Ru₂: C, 42.74; H, 5.89. Found: C, 44.50; H,

6.08. ³¹P{¹H} NMR (C₆D₆): 234.89 (s) and 228.85 (s). ¹H

˚

monoclinic, P2₁/c, a = 13.2784(2) A, b = 14.5962(5) A, c =

˚

26.5498(8) A, β=90.08(1)°, from 20° of data, T=100(2) K, V=

5145.6(3) A , Z=1, fw=4459.94, D_c=1.439 Mg m^-3, μ=0.774

3

˚

mm^-1, data collection and processing:, Bruker KappaApexII

˚

CCD diffractometer, Mo KR (λ=0.710 73 A), graphite mono-

chromator, 69 538 reflections collected, -19 e h e 18, -15 e

k e 21, -37 e l e 39, frame scan width 0.5°, scan speed 1° per

20 s, typical peak mosaicity 0.52°, 17 123 independent reflections

(R_int=0.0361), data processed with Bruker Apex2 Saint soft-

ware; solution and refinement, structure solved by direct methods

with SHELXS, full-matrix least-squares refinement based on

F²with SHELXL-97, 592 parameters with 0 restraints, final

R1=0.0285 (based on F²) for data with I > 2σ(I) and R1=

0.0368 on 17 123 reflections, goodness of fit on F²= 1.005,

-3

˚

largest electron density peak and hole 1.504 and -1.034 e A

.

Reaction of (^tBu-PONOP)Ru(CO) (13) with CO. Formation

of (^tBu-PONOP)Ru(CO)₂(15). To a benzene solution (1 mL) of

complex 13 (10.0 mg, 0.019 mmol) was added 1 equiv of CO

(0.42 mL, 0.019 mmol), leading to a color change from brown to

violet. The solvent was removed under vacuum, resulting in an

orange-violet solid in 96.1% (10.1 mg) yield.

3

NMR (C₆D₆): 10.19 (br s, Ru-OH), 6.84 (t, J_H,H=8.0 Hz,

1H, Ar), 6.79 (t, ³J_H,H=7.9 Hz, 1H, Ar), 6.21 (d, ³J_H,H=8.3 Hz,

1H, Ar), 6.14 (d, ³J_H,H=7.6 Hz, 1H, Ar), 5.95 (d, ³J_H,H=8.3 Hz,

1H, Ar), 5.92 (d, ³J_H,H=7.4 Hz, 1H, Ar), 1.34 (d, ³J_H,H=14.4

3

Hz, 9H, P-C(CH₃)₃), 1.28 (d, J_H,H= 14.4 Hz, 9H, P-C-

Reaction of (^tBu-PONOP)Ru(CO)₂(15) with H₂O. Formation

of (^tBu-PONOP(OH))Ru(H)(CO)₂(16). To a THF solution

(1 mL) of complex 15 (39.2 mg, 0.07 mmol) was added an excess

of H₂O (100-fold, 126 mg, 7 mmol), and the mixture was stirred

for 24 h at room temperature, resulting in a color change from

violet to yellow. The solvent was removed under vacuum,

resulting in a yellow solid in 89.5% (36 mg) yield. Anal. Calcd

for C₂₃H₄₁NO₅P₂Ru: C, 47.99; H, 7.35. Found: C, 48.04; H,

(CH₃)₃), 1.21 (dd, ³J_H,H=14.0 Hz, 18H, P-C(CH₃)₃), -12.21

(dd, ²J_P1,H=²J_P2,H=33.8 Hz, 1H, bridging Ru-H), -15.17 (d,

²J_P,H=28.9 Hz, 1H, Ru-H). ¹³C{¹H} NMR (C₆D₆): 204.59 (dd,

2

²J_P,C=16.5 Hz, J_P,C=4.5 Hz, Ru-CO), 204.13 (dd, J_P,C

=

13.7 Hz, ²J_P,C=2.0 Hz, Ru-CO), 170.88 (br s, Ar), 168.51 (br s,

Ar), 163.20 (s, Ar), 162.91 (s, Ar), 142.28 (s, Ar), 139.24 (s, Ar),

109.16 (s, Ar), 105.17 (s, Ar), 99.05 (d, ²J_P,C=4.7 Hz, Ar), 92.45

(d, ²J_P,C=5.7 Hz, Ar), 42.38 (d, ¹J_P,C=11.4 Hz, P-C(CH₃)₃),

42.17 (d, ¹J_P,C=7.3 Hz, P-C(CH₃)₃), 41.74 (d, ¹J_P,C=22.1 Hz,

P-C(CH₃)₃), 39.63 (d, ¹J_P,C=27.4 Hz, P-C(CH₃)₃), 29.18 (d,

2

7.35. ³¹P{¹H} NMR (C₆D₆): 214.01 (d, J_P,P=245.9 Hz) and

154.59 (d, ²J_P,P=245.9 Hz). ¹H NMR (C₆D₆): 6.88 (t, ³J_H,H

7.7 Hz, 1H, Ar), 6.38 (d, ³J_H,H=7.7 Hz, 1H, Ar), 5.80 (t, ³J_H,H

=

²J_P,C= 4.9 Hz, P-C(CH₃)₃), 28.88 (d, J_P,C= 4.9 Hz, P-

7.7 Hz, 1H, Ar), 1.43 (d, ³J_H,H=13.2 Hz, 9H, P-C(CH₃)₃), 1.27

(d, ³J_H,H=14.3 Hz, 9H, P-C(CH₃)₃), 1.17 (d, ³J_H,H=14.3 Hz,

2

C(CH₃)₃), 28.82 (d, ²J_P,C=4.8 Hz, P-C(CH₃)₃), 28.60 (d, ²J_P,C

=

6.8 Hz, P-C(CH₃)₃). IR (film): ν_CO1946, 1911 cm^-1, ν_Ru-H

3

9H, P-C(CH₃)₃), 0.93 (d, J_H,H=14.3 Hz, 9H, P-C(CH₃)₃),

2063 cm^-1. X-ray structural analysis of 14: crystal data, 2-

-5.98 (dd, ²J_P,H=26.4 Hz, 1H, Ru-H). ¹³C{¹H} NMR (C₆D₆):

204.01 (dd, ²J_P,C=12.7 Hz, Ru-CO), 199.82 (dd, ²J_P,C=8.4 Hz,

Ru-CO), 171.96 (t, ²J_P,C= 1.8 Hz, Ar), 162.41 (d, ³J_P₃_,C=1.4

(C₂₈H₄₆N₂O₇P₂Ru₂) þ C₅H₁₂, colorless prism, 0.20 ꢀ 0.16 ꢀ

3

0.12 mm , triclinic, P1, a=9.4286(4) A, b=14.0069(5) A, c=

˚

14.7373(5) A, R=103.079(2)°, β=99.442(2)°, γ=107.519(2)°,

from 48 616 reflections, T=100(2) K, V=1750.5(1) A , Z=1,

Hz, Ar), 140.25 (s, Ar), 111.15 (s, Ar), 92.66 (d, J_P,C=

3

1

˚

5.1 Hz, Ar), 41.71 (d, J_P,C=6.1 Hz, P-C(CH₃)₃), 40.82 (dd,

fw=1645.64, D_c=1.561 Mg m^-3, μ=1.00 mm^-1; data collection

and processing, Bruker KappaApexII CCD diffractometer, Mo

KR (λ=0.710 73 A), graphite monochromator, Miracol optics,

¹J_P,C=2.7 Hz, ³J_P,C=23.5 Hz, P-C(CH₃)₃), 40.52 (dd, ¹J_P,C

=

6.1 Hz, ³J_P,C=21.7 Hz, P-C(CH₃)₃), 38.84 (dd, ¹J_P,C=2.2 Hz,

2

³J_P,C= 24.2 Hz, P-C(CH₃)₃), 29.58 (d, J_P,C= 4.7 Hz,

˚

2

-14 e h e 14, -21 e k e 21, -22 e l e 22, frame scan width

0.5°, scan speed 1° per 8 s, typical peak mosaicity 0.73°, 48 618

reflections collected, 13 348 independent reflections (R_int=

P-C(CH₃)₃), 28.97 (d, J_P,C= 4.7 Hz, P-C(CH₃)₃), 27.17 (d,

2

²J_P,C= 5.1 Hz, P-C(CH₃)₃), 27.05 (d, J_P,C= 6.9 Hz, P-C-

(CH₃)₃). IR (film): ν_CO2061, 1992, 1948 cm^-1. X-ray structural

analysis of 16: crystal data, C₂₃H₄₁NO₅P₂Ru, colorless plate,

0.031), data processed with Bruker Apex2 Saint software; solu-

tion and refinement, structure solved by direct methods with

SHELXS, full-matrix least-squares refinement based on F²with

SHELXL-97, 453 parameters with 1 restraint, final R1=0.0290

(based on F²) for data with I > 2σ(I) and R1=0.0356 on 13 348

reflections, goodness of fit on F²=1.051, largest electron density

3

˚

0.22 ꢀ 0.18 ꢀ 0.08 mm , monoclinic, P2₁/c, a = 14.7874(4) A,

˚

b=9.2745(3) A, c=19.7832(6) A, β=95.006(2)°, from 40 033

reflections, T=100(2) K, V=2702.83(14) A , Z=4, fw=574.58,

3

˚

D_c= 1.412 Mg m^-3, μ = 0.730 mm^-1; data collection and

processing, Bruker KappaApexII CCD diffractometer, Mo

KR (λ=0.710 73 A), graphite monochromator, Miracol optics,

-3

˚

peak and hole 2.768 and -0.987 e A

.

Reaction of (^tBu-PONOP)Ru(H)₂(CO) (12) with CO. Forma-

tion of (^tBu-PONOP)Ru(CO)₂(15). To a benzene or THF

solution (2 mL) of complex 12 (65.3 mg, 0.122 mmol) in a

-22 e h e 22, -12 e k e 14, -30 e l e 30, frame scan width

0.5°, scan speed 1° per 20 s, typical peak mosaicity 0.67°, 40 033

reflections collected, 10 386 independent reflections (R_int=0.039),

Article

Organometallics, Vol. 28, No. 16, 2009 4805

t

data processed with Bruker Apex2 Saint software; solution and

refinement, structure solved by direct methods with SHELXS, full-

matrix least-squares refinement based on F²with SHELXL-97,

306 parameters with 0 restraint, final R1=0.0291 (basedonF²) for

data with I > 2σ(I) and R1 = 0.0420 on 10 386 reflections,

goodness of fit on F²1.011, largest electron density peak and hole

Reaction of HRu(Cl)(PPh₃)₃with Bu-PONOP (10). Forma-

tion of (^tBu-PONOP)Ru(H)(Cl) (19). To a benzene (5 mL) slurry

of HRu(Cl)(PPh₃)₃(50.0 mg, 0.05 mmol) was added ligand 10

(21.6 mg, 0.05 mmol) as a solid, and the mixture was heated in a

closed vessel at 100 °C for 3 h, forming a clear violet solution.

The solvent was removed under vacuum, resulting in a violet

solid. The residue was dissolved in benzene (1 mL), loaded onto

a silica gel column, and eluted with a pentane/benzene mixture

(1:1, 20 mL) for removal of the generated free PPh₃and then

eluted with benzene until the violet compound reached the

bottom of the column, at which time THF was added for

complete elution of complex 19. The THF was removed under

vacuum, resulting in a sticky violet solid in 72.8% (21.1 mg)

yield. Anal. Calcd for C₂₁H₄₀ClNO₂P₂Ru: C, 46.97; H, 7.51.

Found: C, 47.24; H, 7.54. ³¹P{¹H} NMR (C₆D₆): 212.13 (s).

¹H NMR (C₆D₆): 6.50 (t, ³J_H,H=8.2 Hz, 1H, Ar), 6.11 (d, ³J_H,H

-3

˚

1.006 and -0.587 e A

.

Reaction of (^tBu-PONOP)Ru(H)₂(CO) (12) with MeOTf.

Formation of (^tBu-PONOP)Ru(H)(CO)(OTf) (17). To a ben-

zene solution (1 mL) of complex 12 (20.0 mg, 0.038 mmol) was

added a slight excess of MeOTf (1.2 equiv, 7.4 mg, 0.045 mmol).

The product started to precipitate immediately as an orange-

yellow solid. The solvent was removed under vacuum, resulting

in an orange solid in quantitative yield (25.5 mg). Anal. Calcd

for C₂₃H₄₀F₃NO₆P₂RuS: C, 40.71; H, 5.94. Found: C, 41.00; H,

6.08. ³¹P{¹H} NMR (CD₂Cl₂): 225.94 (s). ¹H NMR (CD₂Cl₂):

8.08 (t, ³J_H,H=8.1 Hz, 1H, Ar), 7.05 (d, ³J_H,H=8.1 Hz, 2H, Ar),

1.35 (m, 36H, P-C(CH₃)₃), -24.97 (br s, 1H, Ru-H). ¹³C{¹H}

NMR (CD₂Cl₂): 203.67 (t, ²J_P,C=9.4 Hz, Ru-CO), 164.71 (s,

Ar), 147.36 (s, Ar), 104.79 (s, Ar), 43.19 (t, ¹J_P,C=6.3 Hz, P-

C(CH₃)₃), 39.88 (t, ¹J_P,C=8.0 Hz, P-C(CH₃)₃), 27.77 (br s, P-

=8.0 Hz, 2H, Ar), 1.40 (vt, J_P,H=7.2 Hz, 18H, P-C(CH₃)₃),

2

1.35 (vt, J_P,H=6.7 Hz, 18H, P-C(CH₃)₃), -31.13 (t, J_P,H

=

20.3 Hz, 1H, Ru-H). ¹³C{¹H} NMR (C₆D₆): 168.25 (t, ²J_P,C

4.2 Hz, Ar), 134.03 (s, Ar), 134.13 (d, Ar), 100.27 (t, ²J_P,C=2.3

=

Hz, Ar), 41.72 (t, ¹J_P,C=3.5 Hz, P-C(CH₃)₃), 39.27 (t, ¹J_P,C

2

C(CH₃)₃), 27.27 (t, J_P,C= 3.0 Hz, P-C(CH₃)₃). ¹⁹F NMR

5.5 Hz, P-C(CH₃)₃), 27.82 (t, J_P,C= 4.0 Hz, P-C(CH₃)₃),

(CD₂Cl₂): -79.68 (s, -CF₃, OTf^-). IR (film): ν_CO1972 cm^-1

,

27.41 (t, J_P,C= 4.2 Hz, P-C(CH₃)₃). IR (film): ν_Ru-H

2

ν

_Ru-H1928 cm^-1

Reaction of (^tBu-PONOP)Ru(H)(Cl)(CO) (11) with MeOTf.

.

2098 cm^-1

.

Reaction of (^tBu-PONOP)Ru(H)Cl (19) with CO. Formation

of (^tBu-PONOP)Ru(H)(CO)(Cl) (20). To a benzene solution

(2 mL) of complex 19 (21.0 mg, 0.037 mmol) in a septum-capped

vial (20 mL) was added 1 equiv of CO (0.83 mL, 0.037 mmol)

with a syringe. The solution was stirred for 2 min, resulting in a

color change to yellow. The solvent was removed under vacuum,

resulting in a light yellow powder in 97.6% (20.3 mg) yield. Anal.

Calcd for C₂₂H₄₀ClNO₃P₂Ru: C, 46.76; H, 7.14. Found: C,

48.88; H, 7.13. ³¹P{¹H} NMR (C₆D₆): 225.20 (s). ¹H NMR

(C₆D₆): 6.54 (t, ³J_H,H=8.2 Hz, 1H, Ar), 6.0 (d, ³J_H,H=8.2 Hz,

2H, Ar), 1.53 (vt, J_P,H=7.2 Hz, 18H, P-C(CH₃)₃), 1.47 (vt,

J_P,H=7.1 Hz, 18H, P-C(CH₃)₃), -3.92 (t, ²J_P,H=21.9 Hz, 1H,

Ru-H). ¹³C{¹H} NMR (C₆D₆): 205.27 (t, ²J_P,C=7.8 Hz, Ru-

CO), 164.34 (t, ²J_P,C=2.8 Hz, Ar), 138.94 (s, Ar), 101.29 (br s,

Formation of (^tBu-PONOP)Ru(H)(CO)(OTf) (17). To a ben-

zene solution (1 mL) of complex 11 (20.0 mg, 0.035 mmol) was

added a slight excess of MeOTf (1.2 equiv, 7.0 mg, 0.042 mmol).

After a few minutes a yellow precipitate started to form. The

solvent was removed under vacuum, resulting in a yellow

powder in 84.6% (20.3 mg) yield. Anal. Calcd for

C₂₃H₄₀F₃NO₆P₂RuS: C, 40.71; H, 5.94. Found: C, 41.11; H,

5.81. ³¹P{¹H} NMR (acetone-d₆): 224.31 (s). ¹H NMR (acetone-

d₆): 8.25 (t, ³J_H,H=8.2 Hz, 1H, Ar), 7.24 (d, ³J_H,H=8.3 Hz, 2H,

3

Ar), 1.43 (vq, 36H, J_P,H=14.9 Hz, P-C(CH₃)₃), -22.01 (vq,

²J_P,H= 17.1 Hz, 1H, Ru-H). ¹³C{¹H} NMR (acetone-d₆):

2

205.90 (t, J_P,C=11.0 Hz, Ru-CO), 165.77 (br s, Ar), 148.80

(s, Ar), 106.31 (t, ³J_P,C=11.0 Hz, Ar), 43.79 (t, ¹J_P,C=6.1 Hz, P-

C(CH₃)₃), 42.06 (t, ¹J_P,C=8.3 Hz, P-C(CH₃)₃), 28.84 (t, ²J_P,C

=

F

Ar), 41.84 (t, J_P,C= 4.2 Hz, P-C(CH₃)₃), 41.63 (t, J_P,C=

1

3.7 Hz, P-C(CH₃)₃), 28.54 (t, ²J_P,C=3.2 Hz, P-C(CH₃)₃). ¹⁹

NMR (acetone-d₆): -78.87 (s, -CF₃, OTf^-). IR (film): ν_CO

1972 cm^-1, ν_Ru-H1928 cm^-1

6.2 Hz, P-C(CH₃)₃), 28.77 (t, ²J_P,C=3.9 Hz, P-C(CH₃)₃), 28.43

(t, ²J_P,C=3.4 Hz, P-C(CH₃)₃). IR (film): ν_CO1918 cm^-1, ν_Ru-H

.

2010 cm^-1

.

Reaction of (^tBu-PONOP)Ru(H₂)(CO) (12) with PhCOCl.

Formation of (^tBu-PONOP)Ru(H)(Cl)(CO) (11). To a C₆D₆

solution (0.5 mL) of 12 (20.0 mg, 0.038 mmol) in a septum-

capped NMR tube was added 1 equiv of PhCOCl (5.3 mg, 0.038

mmol), and the reaction mixture was heated at 80 °C for 5 h,

leading to a color change to yellow. The ³¹P{¹H} NMR spec-

trum exhibited formation of complex 11. Formation of benzal-

dehyde was detected by ¹H NMR, which was quantified using 2-

methoxybenzaldehyde as an internal standard, indicating 57%

yield, and this was confirmed by GC analysis.

Reaction of Ru(Cl)₂(PPh₃)₃with of Pr-PONOP (1). Forma-

tion of (ⁱPr-PONOP)Ru(Cl)₂(PPh₃) (21). To a THF slurry

(2 mL) of Ru(Cl)₂(PPh₃)₃(20.0 mg, 0.02 mmol) was added

ligand 1 (7.2 mg, 0.02 mmol) in THF (1 mL). The reaction

mixture was heated in a closed vessel at 80 °C for 30 min,

resulting in a clear orange solution. The solvent was removed

under vacuum. The residue was dissolved in benzene and added

to a silica gel column, and the column was washed with benzene

(10 mL) for removal of free PPh_3.The complex was eluted with

THF followed by removal of THF under vacuum, resulting in

an orange oil in 90.7% (14.7 mg) yield. Anal. Calcd for

C₃₅H₄₆Cl₂NO₂P₃Ru: C, 54.06; H, 5.96. Found: C, 54.75; H,

6.19. ³¹P{¹H} NMR (C₆D₆): 194.30 (d, ²J_P,P=24.5 Hz), 38.95 (t,

²J_P,P=23.8 Hz). ¹H NMR (C₆D₆): 8.20 (t, ³J_H,H=8.9 Hz, 6H,

i

Reaction of (^tBu-PONOP)Ru(H)(Cl)(CO) (11) with MeI.

Formation of (^tBu-PONOP)Ru(H)(CO)(I) (18). To a benzene

solution (1 mL) of complex 11 (20.0 mg, 0.038 mmol) was added

a large excess of MeI (10-fold, 107.8 mg, 0.76 mmol, 47.3 μL),

and this mixture was stirred for 7 days at room temperature. The

color changed to yellow after 2 days. The solvent was removed

under vacuum, resulting in a yellow solid in 47.8% (11.7 mg)

yield. ³¹P{¹H} NMR (C₆D₆): 227.22 (s). ¹H NMR (C₆D₆): 6.66

(t, ³J_H,H=7.6 Hz, 1H, Ar), 6.05 (d, ³J_H,H=7.6 Hz, 2H, Ar), 1.75

(vt, J_P,H=7.6 Hz, 18H, P-C(CH₃)₃), 1.18 (vt, J_P,H=7.6 Hz,

Ar, PPh₃), 7.09 (t, ³J_H,H=7.6 Hz, 6H, Ar, PPh₃), 7.02 (d, ³J_H,H

=

7.6 Hz, 3H, Ar, PPh₃), 6.77 (t, ³J_H,H=7.6 Hz, 1H, Ar), 6.29 (d,

³J_H,H= 7.6 Hz, 2H, Ar), 3.40 (m, J_H,H= 7.6 Hz, 4H, P-

3

CH(CH₃)₂), 1.39 (dist dd, ³J_H,H=6.4 Hz, ⁴J_P,H=12.7 Hz, 12H,

3

4

P-CH(CH₃)₂), 0.98 (dist dd, J_H,H=7.6 Hz, J_P,H=15.3 Hz,

12H, P-CH(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): 163.36 (br s, Ar),

140.80 (s, Ar), 140.34 (d, J_P,C= 38.8 Hz, Ar, PPh₃), 135.34

2

18H, P-C(CH₃)₃), -11.94 (t, J_P,H= 21.6 Hz, 1H, Ru-H).

¹³C{¹H} NMR (C₆D₆): 206.22 (t, J_P,C= 10.0 Hz, Ru-CO),

(d, J_P,C=9.6 Hz, Ar, PPh₃), 129.28 (br d, ²J_P,C=1.4 Hz, Ar,

2

163.02 (t, ²J_P,C=3.5 Hz, Ar), 141.93 (s, Ar), 102.37 (br s, Ar),

43.31 (t, ¹J_P,C=2.7 Hz, P-C(CH₃)₃), 41.83 (t, ¹J_P,C=7.6 Hz, P-

PPh₃), 127.48 (d, ²J_P,C=8.8 Hz, Ar, PPh₃), 102.15 (s, Ar), 29.56

(vt, J_P,C=7.8 Hz, P-CH(CH₃)₂), 19.32 (s, P-CH(CH₃)₂), 18.41

(s, P-CH(CH₃)₂).

C(CH₃)₃), 31.56 (t, ²J_P,C=3.6 Hz, P-C(CH₃)₃), 27.80 (t, ²J_P,C

=

2.8 Hz, P-C(CH₃)₃). IR (film): ν_CO1947.2 cm^-1, ν_Ru-H2139.7

cm^-1. ESI-MS: ES^þm/z 530.07 (M^þ, calcd m/z 530.15); ES^-m/z

126.64 (calcd m/z 126.90).

Reaction of RuCl₂(PPh₃)₃with (^tBu-PONOP) (10). Formation

of (^tBu-PONOP)Ru(Cl)₂(22). To a THF (2 mL) slurry

of RuCl₂(PPh₃)₃(40 mg, 0.04 mmol) was added ligand 10

4806 Organometallics, Vol. 28, No. 16, 2009

Salem et al.

1

(16.7 mg, 0.04 mmol) as a solid, and the solution was stirred at

room temperature for 1 h, resulting in a clear green solution. The

solvent was removed under vacuum, resulting in a brown solid.

The residue was dissolved in benzene (1 mL) and loaded onto a

silica gel column, followed by elution of the column with a

pentane/benzene mixture (1:1, 5 mL) for removal of the gener-

ated free PPh₃. Subsequent elution with benzene removed a

brown undefined minor byproduct. Finally, complex 22 was

eluted with THF. The THF was removed under vacuum,

resulting in a greenish blue solid in 73.1% (17.4 mg) yield. Anal.

Calcd for C₂₁H₃₉Cl₂NO₂P₂Ru: C, 44.14; H, 6.88. Found: C,

45.08; H, 7.19. ³¹P{¹H} NMR (acetone-d₆): 181.16 (s). ¹H NMR

142.60 (s, Ar), 129.09 (s, Ar), 102.42 (s, Ar), 43.32 (t, J_P,C

3.2 Hz, P-C(CH₃)₃), 27.42 (s, P-C(CH₃)₃).

=

Acknowledgment. This work was supported by the

Israel Science Foundation, by the donors of the Petro-

leum Research Fund, administered by the American

Chemical Society, and by The Helen and Martin Kimmel

Center for Molecular Design. D.M. holds the Israel Matz

Professorial Chair of Organic Chemistry.

Supporting Information Available: Figures giving NMR spec-

tra of complex 13 and CIF files containing X-ray crystallographic

data for complexes 2, 4, 8a,b, 12, and 14-16. This material is

available free of charge via the Internet at http://pubs.acs.org.

3

(acetone-d₆): 7.43 (t, J_H,H=8.1 Hz, 1H, Ar), 7.11 (d, J_H,H=

8.1 Hz, 2H, Ar), 1.22 (vt, J_P,H= 6.6 Hz, 36H, P-C(CH₃)₃).

3

¹³C{¹H} NMR (acetone-d₆): 171.95 (t, J_P,C= 3.2 Hz, Ar),

Article Doi

Formation of stable trans-dihydride ruthenium(II) and 16-electron ruthenium(0) complexes based on phosphinite PONOP pincer ligands. Reactivity toward water and electrophiles

DOI: 10.1021/om9004077

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Authors:

Article abstract of DOI:10.1021/om9004077

Full text of DOI:10.1021/om9004077

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