Synthesis of Palladium Complexes with ortho-Functionalized Aryl Ligands

Article abstract of DOI:10.1021/om9905963

The complexes [Pd(C₆H₄X-2)BrL₂] (L₂ = trans-(PR₃)₂, R = Ph, X = CH=CH₂ (1a), CHO (1b), C(O)Me (1c), CN (1d); R = p-To = 4-tolyl, X = CH=CH₂ (1a′); L₂ = bpy = 2,2′-bipyridine, X = CHO (2b), C(O)Me (2c), CN (2d); L₂ = tmeda = N,N,N′,N′-tetramethylethylenediamine, X = CHO (2b′), CN (2d′)) have been prepared by oxidative addition of the corresponding bromoarene BrC₆H₄X-2 to "Pd(dba)₂" (=[Pd₂(dba)₃]·dba, dba = dibenzylideneacetone) in the presence of the appropriate ligand. The compound [Pd{C₆H₄(CH=CH₂)-2}(bpy)(PPh₃)]TfO (3a; TfO = CF₃SO₃) has been obtained by reacting 1a with bpy in the presence of TlOTf. The cyclopalladated [Pd{κ²-C,O-C₆H₄{C(O)Me}-2}(bpy)]TfO (4c) has been prepared from 2c and TlOTf. The dimeric complexes [Pd(μ-Br)(C₆H₄X-2)(PR₃)]₂ (R = Ph, X = CHO (5b), C(O)-Me (5c), CN (5d); R = o-To = 2-tolyl, X = CHO (5b″), CN (5d″)) have been synthesized by reacting complexes 1b-d with [PdCl₂(NCPh)₂] in a 2:1 molar ratio or C₆H₄Br-1-X-2 with "Pd(dba)₂" and P(o-To)₃ in 1:1:1 molar ratio. The latter method leads to the monomeric [Pd{κ²-C,O-C₆H ₄{C(O)Me}-2})Br{P(o-To)₃}] (6c″) when X = C(O)Me. The complex 2c reacts with the alkyne PhC≡CPh or EtC≡CEt and TlOTf to give 1-methyl-2,3-diphenyl-1H-indenol (7) or 1-methyl-2,3-diethyl-1H-indenol (8), respectively. The crystal structures of complexes 1a·2CH₂Cl₂, 1b·CH₂Cl₂, 2b,d, and 6c″ have been determined by X-ray diffraction studies. An interesting supramolecular layered structure is formed through CN. . .H-C_bpy and Br. . .H-C_bpy hydrogen bonds in complex 2d.

Full text of DOI:10.1021/om9905963

752
Organometallics 2000, 19, 752-760
Syn th esis of P a lla d iu m Com p lexes w ith
or th o-F u n ction a lized Ar yl Liga n d s
J ose´ Vicente,*,† J ose´-Antonio Abad,*,‡ Elo´ısa Mart´ınez-Viviente, and
M. Carmen Ram´ırez de Arellano§
Grupo de Quı´mica Organometa´lica, Departamento de Qu´ımica Inorga´nica, Facultad de
Quı´mica, Universidad de Murcia, Apartado 4021, Murcia, 30071 Spain
Peter G. J ones|
Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany
Received J uly 28, 1999
The complexes [Pd(C6H4X-2)BrL2] (L2 ) trans-(PR3)2, R ) Ph, X ) CHdCH2 (1a ), CHO
(1b), C(O)Me (1c), CN (1d ); R ) p-To ) 4-tolyl, X ) CHdCH2 (1a ′); L2 ) bpy ) 2,2′-bipyridine,
X ) CHO (2b), C(O)Me (2c), CN (2d ); L2 ) tmeda ) N,N,N′,N′-tetramethylethylenediamine,
X ) CHO (2b′), CN (2d ′)) have been prepared by oxidative addition of the corresponding
bromoarene BrC6H4X-2 to “Pd(dba)2” ()[Pd2(dba)3]‚dba, dba ) dibenzylideneacetone) in the
presence of the appropriate ligand. The compound [Pd{C6H4(CHdCH2)-2}(bpy)(PPh3)]TfO
(3a ; TfO ) CF3SO3) has been obtained by reacting 1a with bpy in the presence of TlOTf.
The cyclopalladated [Pd{κ2-C,O-C6H4{C(O)Me}-2}(bpy)]TfO (4c) has been prepared from 2c
and TlOTf. The dimeric complexes [Pd(µ-Br)(C6H4X-2)(PR3)]2 (R ) Ph, X ) CHO (5b), C(O)-
Me (5c), CN (5d ); R ) o-To ) 2-tolyl, X ) CHO (5b′′), CN (5d ′′)) have been synthesized by
reacting complexes 1b-d with [PdCl2(NCPh)2] in a 2:1 molar ratio or C6H4Br-1-X-2 with
“Pd(dba)2” and P(o-To)3 in 1:1:1 molar ratio. The latter method leads to the monomeric
[Pd{κ2-C,O-C6H4{C(O)Me}-2})Br{P(o-To)3}] (6c′′) when X ) C(O)Me. The complex 2c reacts
with the alkyne PhCtCPh or EtCtCEt and TlOTf to give 1-methyl-2,3-diphenyl-1H-indenol
(7) or 1-methyl-2,3-diethyl-1H-indenol (8), respectively. The crystal structures of complexes
1a ‚2CH2Cl2, 1b‚CH2Cl2, 2b,d , and 6c′′ have been determined by X-ray diffraction studies.
An interesting supramolecular layered structure is formed through CN‚‚‚H-Cbpy and
Br‚‚‚H-Cbpy hydrogen bonds in complex 2d .
In tr od u ction
ated reagents.15 Thus, we have prepared complexes
containing aryl groups such as C6H(OMe)3-3,4,5-CHO-
2, C6H(OMe)3-2,3,4-X-6 (X ) CHO, C(O)Me, CH2OEt,
C(O)NHBut),12,16-18 and C6H3(CHO)2-2,5.19 Some of
these complexes show interesting supramolecular struc-
tures with hydrogen bonds involving the functional
Arylpalladium chemistry constitutes a subject of
current interest because of the involvement of such
compounds in many palladium-catalyzed organic
reactions.1-3 We are interested in the synthesis and
structure of palladium complexes with functionalized
aryl ligands in order to study their reactivity with
alkynes,4-12 isocyanides,12,13 CO13,14 and other unsatur-
(7) Vicente, J .; Saura-Llamas, I.; Ram´ırez de Arellano, M. C. J .
Chem. Soc., Dalton Trans. 1995, 2529.
(8) Vicente, J .; Saura-Llamas, I.; Palin, M. G.; J ones, P. G. J . Chem.
Soc., Dalton Trans. 1995, 2535.
† E-mail: jvs@fcu.um.es. WWW: http://www.scc.um.es/gi/gqo/.
‡ E-mail: jaab@fcu.um.es.
(9) Vicente, J .; Abad, J . A.; Ferna´ndez-de-Bobadilla, R.; J ones, P.
G.; Ram´ırez de Arellano, M. C. Organometallics 1996, 15, 24.
(10) Vicente, J .; Abad, J . A.; Gil-Rubio, J . Organometallics 1996,
15, 3509.
(11) Vicente, J .; Abad, J . A.; Bergs, R.; J ones, P. G.; Ram´ırez de
Arellano, M. C. Organometallics 1996, 15, 1422.
(12) Vicente, J .; Abad, J . A.; Shaw, K. F.; Gil-Rubio, J .; Ram´ırez de
Arellano, M. C.; J ones, P. G. Organometallics 1997, 16, 4557.
(13) Vicente, J .; Saura-Llamas, I.; Turp´ın, J .; Ram´ırez de Arellano,
M. C.; J ones, P. G. Organometallics 1999, 18, 2683.
(14) Vicente, J .; Abad, J . A.; Frankland, A. D.; Ram´ırez de Arellano,
M. C. Chem. Commun. 1997, 959.
§ To whom correspondence should be addressed regarding the X-ray
diffraction studies of complexes 1a ‚2CH2Cl2, 2b, and 2d . Present
address: Departamento de Qu´ımica Orga´nica, Facultad de Qu´ımica,
Universidad de Valencia, 46100 Valencia, Spain. E-mail:
M.Carmen.Ramirezdearellano@uv.es.
| To whom correspondence should be addressed regarding the X-ray
diffraction study of complexes 1b ‚CH2Cl2 and 6c′′. E-mail: jones@
xray36.anchem.nat.tu-bs.de.
(1) Heck, R. F. Palladium Reagents in Organic Synthesis; Academic
Press: New York, 1985.
(2) Tsuji, J . Palladium Reagents and Catalysts; Wiley: Chichester,
U.K., 1995.
(3) Hartwig, J . F. Angew. Chem., Int. Ed. 1998, 37, 2046.
(4) Vicente, J .; Abad, J . A.; Gil-Rubio, J . J . Organomet. Chem. 1992,
436, C9.
(15) Abad, J . A. Gazz. Chim. Ital. 1997, 127, 119.
(16) Vicente, J .; Abad, J . A.; J ones, P. G. Organometallics 1992, 11,
3512.
(17) Vicente, J .; Abad, J . A.; Gil-Rubio, J .; J ones, P. G.; Bembenek,
E. Organometallics 1993, 12, 4151.
(5) Vicente, J .; Abad, J . A.; Gil-Rubio, J .; J ones, P. G. Inorg. Chim.
Acta 1994, 222, 1.
(6) Vicente, J .; Abad, J . A.; Gil-Rubio, J .; J ones, P. G. Organome-
tallics 1995, 14, 2677.
(18) Vicente, J .; Abad, J . A.; Bergs, R.; J ones, P. G.; Bautista, D. J .
Chem. Soc., Dalton Trans. 1995, 3093.
(19) Vicente, J .; Abad, J . A.; Rink, B.; Herna´ndez, F.-S.; Ram´ırez
de Arellano, M. C. Organometallics 1997, 16, 5269.
10.1021/om9905963 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 02/04/2000

Pd Complexes with Functionalized Aryl Ligands
Organometallics, Vol. 19, No. 5, 2000 753
were carried out as described earlier.30 Long-range CH cor-
relations of 2b, 2b′, 2c, 2d , and 2d ′ were determined on a
Bruker DPX 300 apparatus. The compounds “Pd(dba)2” ([Pd2-
(dba)3]‚dba, dba ) dibenzylideneacetone)1,31 and [PdCl2-
(NCPh)2]32 were prepared as reported previously. The 2-halo-
arenes were purchased from Fluka. In the complexes containing
the ligand 2,2′-bipyridine, the atoms marked with a prime
correspond to the ring trans to the aryl group.
groups incorporated in the aryl group, and we report in
this paper an interesting layer structure formed in such
a manner. We have also studied the reactivity of these
aryl complexes with alkynes, obtaining different prod-
ucts depending on the aryl substituents, the other
ligands coordinated to the palladium atom, and the
reaction conditions. In some cases we have obtained
highly functionalized indenylpalladium derivatives,11
but in other cases depalladation occurs, giving organic
compounds such as indenones and indenols,10 benzo-
fulvenes, or spirocyclic compounds.5,6,9,10,12 These sto-
ichiometric reactions could help to elucidate the mech-
anism of some palladium-catalyzed reactions involving
the same haloarenes. Thus, indenones and indenols
have been prepared by reacting 2-halobenzaldehyde and
2-haloaryl ketones with alkynes using Pd(0) as
catalyst20-23 and 3-oxo-1,3-dihydro-1-isobenzofuranyl
alkanoates have been prepared by reacting 2-bromoben-
zaldehyde with sodium alkanoates under carbon mon-
oxide pressure in the presence of a catalytic amount of
[PdCl2(PPh3)2].24
The above-mentioned palladium complexes were pre-
pared using the corresponding arylmercurials as trans-
metalating agents, since they are compatible with the
reactive substituents present in the aryl groups. In this
paper, we describe the synthesis of (o-X-phenyl)palla-
dium complexes with X ) CHO, C(O)Me, CHdCH2, and
CN through oxidative addition reactions. We have used
this method for the preparation of o-aminoaryl deriva-
tives.14,25 To the best of our knowledge, the only (o-CHO-
aryl)- or (o-C(O)Me-aryl)palladium complexes are our
trimethoxy derivatives and a series of (2,5-diformyl-
phenyl)palladium complexes;16,17,19 furthermore, very
few (o-alkenylaryl)palladium compounds are known,26
among which are those prepared by us from (2,3,4-
trimethoxy-6-formylphenyl)palladium derivatives and
phosphorus ylides.18 2-Iodoalkenyl arenes have been
reacted with diphenylacetylene, norbornene, or meth-
ylenecyclopropane to give various organic compounds
using Pd(0) as catalyst.27 The compound [Pd{C6H4CN-
2}Cl(PPh3)2} appeared in a patent.28 Recently, the
catalytic synthesis of 2,3-diphenylindenone has been
reported, resulting from the reaction of 2-iodobenzoni-
trile with diphenylacetylene using Pd(dba)2 as cata-
lyst.29
Syn t h esis of tr a n s-[P d {C6H 4(CHdCH 2)-2}Br (P P h 3)2]
(1a ). “Pd(dba)2” (150 mg, 0.26 mmol), PPh3 (137 mg, 0.52
mmol), and 2-bromostyrene (51 µL, 0.39 mmol) were mixed
under nitrogen in toluene (15 mL). The mixture was heated
quickly to boiling and refluxed for 10 min. The color changed
from red to yellow. The solvent was removed under vacuum,
the residue extracted with dichloromethane, and the extracts
filtered over anhydrous MgSO4. From this point the workup
was carried out in the air. The resultant yellow solution was
evaporated under vacuum to dryness and diethyl ether added,
precipitating a yellow solid which was filtered, washed with
diethyl ether, and dried to give 1a . Yield: 158 mg, 75%. Mp:
115 °C dec. Anal. Calcd for C44H37BrP2Pd: C, 64.92; H, 4.58.
Found: C, 64.93; H, 4.50. 1H NMR (300 MHz, CDCl3): δ 7.8-
3
7.15 (several m, 30H, PPh3), 6.97 (dd, 1H, CHdCH2, J HH
)
17 Hz, 3J HH ) 11 Hz), 6.91-6.86 (m, 1H, C6H4), 6.47-6.42 (m,
2H, C6H4), 6.28-6.23 (m, 1H, C6H4), 5.20 (dd, 1H, CHdCH2
2
3
trans to H, J HH ) 1 Hz, J HH ) 17 Hz), 4.84 (dd, 1H, CHd
CH2 cis to H, J HH ) 1 Hz, J HH ) 11 Hz). 13C NMR (50 MHz,
2
3
2
CDCl3): δ 158.28 (t, C-Pd C6H4, J PC ) 3 Hz), 142.04 (t,
3
4
C-CHdCH2, J PC ) 3 Hz), 141.08 (t, CHdCH2, J PC ) 2 Hz),
135.63 (t, C6 C6H4, 3J PC ) 5 Hz), 134,70 (t, ortho C’s PPh3, J PC
) 6 Hz), 131,27 (t, ipso C’s PPh3, J PC ) 23 Hz), 129.66 (s, para
C’s PPh3), 127.69 (t, meta C’s PPh3, J PC ) 5 Hz), 126.71 (s,
CH C6H4), 126.06 (s, CH C6H4), 122.67 (s, CH C6H4), 111.64
(s, CH2). 31P NMR (121 MHz, CDCl3): δ 22.87 (s).
Syn th esis of tr a n s-[P d{C6H4(CHdCH2)-2}Br {P (p-To)3}2]
(1a ′). Complex 1a ′ was similarly prepared from “Pd(dba)2” (150
mg, 0.26 mmol), P(p-To)3 (p-To ) 4-tolyl; 159 mg, 0.52 mmol),
and 2-bromostyrene (51 µL, 0.39 mmol). Color: pale brown.
Yield: 160 mg, 68%. Mp: 138 °C dec. Anal. Calcd for C50H49
-
BrP2Pd: C, 66.86; H, 5.50. Found: C, 66.70; H, 5.46. 1H NMR
(300 MHz, CDCl3): δ 7.8-6.8 (several m, 26H), 6.41 (m, 2H,
C6H4, J ) 4 Hz), 6.22 (m, C6H4, 1H), 5.20 (dd, 1H, CHdCH2,
2
3
H trans to H, J HH ) 1 Hz, J HH ) 17 Hz), 4.81 (dd, 1H, CHd
2
3
CH2, H cis to H, J HH ) 1 Hz, J HH ) 11 Hz), 2.30 (s, 18H,
Me). 13C NMR (50 MHz, CDCl3): δ 158,87 (t, C-Pd, J PC ) 3
2
3
Hz), 142.00 (t, C-CHdCH2, J PC ) 3 Hz), 141.42 (t, CHdCH2,
4J PC ) 2 Hz), 139.48 (s, para C’s P(p-To)3), 135.60 (t, C6 C6H4,
3J PC ) 5 Hz), 134.60 (t, ortho C’s P(p-To)3, J PC ) 6 Hz), 128.39
(t, meta C’s P(p-To)3, J PC ) 5 Hz), 128.36 (t, ipso C’s P(p-To)3,
J PC ) 24 Hz), 126.48 (s, CH C6H4), 125.84 (s, CH C6H4), 122.17
(s, CH C6H4), 119.29 (s, CH2), 21.36 (s, Me). 31P NMR (121
MHz, CDCl3): δ 21.01 (s).
Exp er im en ta l Section
Syn th esis of tr a n s-[P d {C6H4(CHO)-2}Br (P P h 3)2] (1b).
Complex 1b was similarly prepared from “Pd(dba)2” (150 mg,
0.26 mmol), PPh3 (137 mg, 0.52 mmol), and 2-bromobenzal-
dehyde (45 µL, 0.39 mmol). Color: pale yellow. Yield: 168 mg,
79%. Mp: 184 °C dec. Anal. Calcd for C43H35BrOP2Pd: C,
The IR and NMR spectra, elemental analyses, conductivity
measurements in acetone and melting-point determinations
(20) Larock, R. C.; Doty, M. J .; Cacchi, S. J . Org. Chem. 1993, 58,
4579.
(21) Quan, L. G.; Gevorgyan, V.; Yamamoto, Y. J . Am. Chem. Soc.
1999, 121, 3545.
(22) Gevorgyan, V.; Quan, L. G.; Yamamoto, Y. Tetrahedron Lett.
1999, 40, 4089.
(23) Quan, L. G.; Gevorgyan, V.; Yamamoto, Y. J . Am. Chem. Soc.
1999, 121, 9485.
(24) Cho, C. S.; Baek, D. Y.; Shim, S. C. J . Heterocycl. Chem. 1999,
36, 289.
(25) Vicente, J .; Abad, J . A.; Sa´nchez, J . A. J . Organomet. Chem.
1988, 352, 257.
(26) Miller, R. G.; Stauffer, R. D.; Fahey, D. R.; Parnell, D. R. J .
Am. Chem. Soc. 1970, 92, 1511.
1
63.29; H, 4.32. Found: C, 63.22; H, 4.36. H NMR (300 MHz,
CDCl3): δ 9.69 (s, 1H, CHO), 7.55-6.58 (several m, 34 H, PPh3
and C6H4). 13C NMR (50 MHz, CDCl3): δ 194.54 (s, CHO),
2
168.52 (t, C-Pd, J PC ) 4 Hz), 140.07 (s, C-CHO), 135.14 (t,
3
C6 C6H4, J PC ) 4 Hz), 134.51 (t, ortho C’s PPh3, J PC ) 6 Hz),
133.04 (s, CH C6H4), 131.09 (s, CH C6H4), 130.71 (t, ipso C’s
PPh3, J PC ) 23 Hz), 129.83 (s, para C’s PPh3), 127.86 (t, meta
C’s PPh3, J PC ) 5 Hz), 122.51 (s, C4 C6H4). 31P NMR (121 MHz,
(27) Grigg, R.; Kennewell, P.; Teasdale, A.; Sridharan, V. Tetrahe-
dron Lett. 1993, 34, 153.
(28) Fitton, P. S.; Rick, E. A. U.S. Patent 3,674,825; Chem. Abstr.
1972, 77, 88664t.
(30) Vicente, J .; Chicote, M. T.; Gonza´lez-Herrero, P.; J ones, P. G.
Inorg. Chem. 1997, 36, 5735.
(31) Takahashi, Y.; Ito, T.; Sakai, S.; Ishii, U. J . Chem. Soc., Chem.
Commun. 1970, 1065.
(29) Larock, R. C.; Tian, Q.; Pletnev, A. A. J . Am. Chem. Soc. 1999,
121, 1, 3238.
(32) Doyle, J . R.; Slade, P. E.; J onassen, H. B. Inorg. Synth. 1960,
6, 218.

754 Organometallics, Vol. 19, No. 5, 2000
Vicente et al.
CDCl3): δ 23.17 (s). IR (cm-1): ν(CO) 1682 (solid) 1684
(dichloromethane solution).
CH2), 2.73 (s, 3H, Me), 2.70 (s, 3H, Me), 2.53 (s, 3H, Me), 2.17
(s, 3H, Me).13C NMR (50 MHz, CDCl3): δ 196.99 (s, CHO),
158.98 (s, C-Pd), 141.67 (s, C-CHO), 136.08 (s, C6), 131.26
(s, C5), 128.89 (s, C3), 123.46 (s, C4), 62.72 (s, CH2), 58.45 (s,
CH2), 51.74 (s, Me), 49.68 (s, Me), 49.27 (s, Me), 47.96 (s, Me).
IR (cm-1): ν(CO) 1682 (Nujol).
Syn th esis of tr a n s-[P d{C6H4{C(O)Me}-2}Br (P P h 3)2] (1c).
“Pd(dba)2” (200 mg, 0.35 mmol), PPh3 (184 mg, 0.70 mmol),
and 2-bromoacetophenone (71 µL, 0.52 mmol) were mixed in
toluene (20 mL), under nitrogen. The mixture is slowly heated
and kept at the boiling point for 10 min. The workup was
continued in the air. The residue was extracted with dichloro-
methane (4 × 10 mL), and the combined extracts were filtered
over anhydrous MgSO4. The resultant solution was evaporated
and diethyl ether added, precipitating a solid which was
filtered, washed with diethyl ether, and dried to give 1c as a
yellow solid. Yield: 209 mg, 72%. Mp: 285 °C dec. Anal. Calcd
for C44H37BrOP2Pd: C, 63.67; H, 4.49. Found: C, 63.40; H,
4.80. 1H NMR (300 MHz, CDCl3; -60 °C): δ 7.60-7.17 (several
Syn th esis of [P d {C6H4{C(O)Me}-2}Br (bp y)] (2c). “Pd-
(dba)2” (300 mg, 0.52 mmol), bpy (81 mg, 0.52 mmol), and
2-bromoacetophenone (101 mg, 0.75 mmol) were mixed in
toluene (20 mL), under nitrogen. The mixture was slowly
heated until the color changed to brown (1 h 20 min, 90 °C).
Workup as for 1c rendered yellow 2c. Yield: 180 mg, 75%.
Mp: 210 °C. Anal. Calcd for C18H15BrN2OPd: C, 46.83; H, 3.27;
N, 6.07. Found: C, 46.68; H, 3.17; N, 5.90. 1H NMR (300 MHz,
3
CDCl3; -60 °C): δ 9.45 (d, 1H, bpy, J HH ) 5 Hz), 8.14 (m,
3
3
m, 31H), 6.76 (d, 1H, C6H4, J HH ) 7 Hz), 6.65 (t, 1H, C6H4,
3H), 8.05 (t, 1H, J HH ) 8 Hz), 7.83 (t, 2H, J HH ) 8 Hz), 7.63
3
3J HH ) 7 Hz), 6.57 (t, 1H, C6H4, J HH ) 7 Hz), 1.76 (s, 3H,
(t, 1H, J HH ) 6 Hz), 7.57 (d, 1H, J HH ) 6 Hz), 7.35-7.23 (m,
2H), 7.13 (t, 1H, J HH ) 7 Hz), 2.86 (s, 3H, Me). 13C NMR (50
MHz, CDCl3): δ 203.17 (s, CO), 152.70 (s, C-Pd), 150.95 (bs,
C6 and 6′ bpy), 144.44 (C-C(O)Me), 138.66 (bs, C4 and 4′ bpy),
136.94 (s, C6 C6H4), 129.96 (s, C5 C6H4), 129.71 (s, C3 C6H4),
126.57 (b s, C5 and 5′ bpy), 123.30 (s, C4 C6H4), 121.70 (b s,
C3 and 3′ bpy), 30.30 (s, Me). IR (cm-1): ν(CO) 1660 (Nujol).
Syn th esis of [P d {C6H4(CN)-2}Br (bp y)] (2d ). “Pd(dba)2”
(150 mg, 0.26 mmol), bpy (41 mg, 0.26 mmol), and 2-bro-
mobenzonitrile (71 mg, 0.39 mmol) were mixed in toluene (15
mL) under nitrogen. The red mixture was heated for 30 min,
until the temperature reached 100 °C. The color changed to
greenish brown. Workup was then continued in air. The
solvent was removed under vacuum and the residue extracted
with dichloromethane (2 × 10 mL). The combined extracts
were filtered over anhydrous MgSO4, the resulting solution
was evaporated to dryness, and the residue was triturated with
diethyl ether, giving a yellow solid of 2d which was filtered,
washed with diethyl ether, and dried. Yield: 66 mg, 56%.
Mp: 175 °C dec. Anal. Calcd for C17H12BrN3Pd: C, 45.93; H,
2.72; N, 9.45. Found: C, 45.80; H, 2.45; N, 9.11. 1H NMR (200
MHz, CDCl3): δ 9.16 (d, 1H, H6′ bpy, 3J HH ) 5 Hz), 8.69-8.63
Me). 13C NMR (50 MHz, CDCl3): δ 198.40 (s, CO), 165.68 (s,
C-Pd), 141.04 (s, CC(O)Me), 135.32 (bs, C6 C6H4), 134.67 (t,
ortho C’s PPh3, J PC ) 5 Hz), 133.24 (s, CH C6H4), 131,26 (t,
ipso C’s PPh3, J PC ) 22 Hz), 129.50 (s, para C’s PPh3), 127.68
(bs, meta C’s PPh3), 121.83 (s, CH C6H4), 26.76 (s, Me). 31P
NMR (121 MHz, CDCl3): δ, 23.05 (s). IR (cm-1): ν(CO) 1660
(Nujol).
Syn th esis of tr a n s-[P d {C6H4(CN)-2}Br (P P h 3)2] (1d ).
Complex 1d was prepared as described for 1a from “Pd(dba)2”
(150 mg, 0.26 mmol), PPh3 (137 mg, 0.52 mmol), and 2-bromo-
benzonitrile (71 mg, 0.39 mmol). Color: white. Yield: 163 mg,
76%. Mp: 215 dec. Anal. Calcd for C43H34NP2Pd: C, 63.53; H,
4.22; N, 1.72. Found: C, 63.28; H, 4.36; N, 1.64. 1H NMR (300
MHz, CDCl3): δ 7.7-7.1 (several m, 31 H), 6.61-6.55 (m, 1H),
6.41-6.39 (m, 2H). 13C NMR (75 MHz, CDCl3): δ 167.14 (t,
2
3
C-Pd, J PC ) 5 Hz), 135.67 (t, C6 C6H4, J PC ) 4 Hz), 134,68
(t, ortho C’s PPh3, J PC ) 6 Hz), 132.84 (s, CH C6H4), 130.61 (t
ipso C’s PPh3, J PC ) 23 Hz), 129.94 (s, para C’s PPh3), 129.71
(s, CH C6H4), 127.91 (t, meta C’s PPh3, J PC ) 5 Hz), 122.20 (s,
3
C4 C6H4), 121.79 (s, CN), 120.29 (t, C-CN, J PC ) 4 Hz). 31P
NMR (121 MHz, CDCl3): δ 23.32 (s). IR (cm-1): ν(CN) 2212
(Nujol).
(m, 2H, H3 and H3′ bpy), 8.30 (dt, 2H, H4 and 4′ bpy, J HH
)
7 Hz, J HH ) 1 Hz), 7.84 (t, 1H, H5′ bpy, J HH ) 6 Hz), 7.65 (t,
1H, H5 bpy, J HH ) 6 Hz), 7.55-7.51 (m, aryl H3, aryl H6, and
H6 bpy, 3H), 7.28 (dt, 1H, aryl H5, J HH ) 7 Hz, J HH ) 1 Hz),
7.10 (t, 1H, aryl H4, J HH ) 7 Hz). 13C NMR (50 MHz,
d6-dimethyl sulfoxide): δ 156.24 (s, C1 C6H4), 155.83 (s, C2
bpy), 153.66 (s, C2′ bpy), 149.69 (s, C6 bpy), 149.43 (s, C6′ bpy),
140.40 (s, 2C, C4 and 4′ bpy), 137.34 (s, C6 C6H4), 132.38 (s,
C3 C6H4), 130.21 (s, C5 C6H4), 127.70 (s, C5 bpy), 127.37 (s,
C5′ bpy), 123.98 (s, C3 bpy), 123.89 (s, C4 C6H4), 123.25 (s,
C3′ bpy), 121.41 (s, CN), 118.88 (s, C-CN). IR (cm-1): ν(CN)
2218 (Nujol).
Syn th esis of [P d {C6H4(CN)-2}Br (tm ed a )] (2d ′). Complex
2d ′ was similarly prepared from “Pd(dba)2” (150 mg, 0.26
mmol), tmeda (39 µL, 0.26 mmol), and 2-bromobenzonitrile (71
mg, 0.39 mmol), but the mixture was slowly heated to boiling
and kept at the boiling point for a further 10 min. Color: pale
brown. Yield: 67 mg, 63%. Mp: 141 °C dec. Anal. Calcd for
Syn th esis of [P d {C6H4(CHO)-2}Br (bp y)] (2b). “Pd(dba)2”
(150 mg, 0.26 mmol), bpy (2,2′-bipyridine; 41 mg, 0.26 mmol),
and 2-bromobenzaldehyde (45 µL, 0.39 mmol) were mixed in
toluene (15 mL) under nitrogen. The red mixture was slowly
heated over 1 h 20 min until the color changed to orange-yellow
(at ca. 90 °C) and then evaporated to dryness. Workup as for
1c rendered 2b as a yellow solid. Yield: 93 mg, 80%. Mp: 190
°C dec. Anal. Calcd for C17H13BrN2OPd: C, 45.62; H, 2.93; N,
1
6.26. Found: C, 45.74; H, 2.84; N, 6.10. H NMR (200 MHz,
3
CDCl3): δ 11.09 (s, 1H, CHO), 9.42 (d, 1H, H6′ bpy, J HH ) 5
Hz), 8.14-8.05 (several m, 3H, H3, H3′ and H4′ bpy), 8.00 (td,
3
4
1H, H4 bpy, J HH ) 8 Hz, J HH ) 2 Hz), 7.78 (dd, 2H, aryl H3
3
4
and H6, J HH ) 8 Hz, J HH ) 1 Hz), 7.64-7.57 (m, 1H, H5′
3
4
bpy), 7.52 (dd, 1H, H6 bpy, J HH ) 6 Hz, J HH ) 1 Hz), 7.31-
3
7.21 (m, 2H, aryl H5 and H5 bpy), 7.09 (t, 1H, aryl H4, J HH
) 7 Hz). 13C NMR (50 MHz, CDCl3): δ 196.73 (s, CHO), 159.50
(s, C-Pd), 156.12 (s, C2 bpy), 153.44 (s, C2′ bpy), 150.67 (s,
C6 or 6′ bpy), 150.59 (s, C6′ or 6 bpy), 141.39 (s, C-CHO),
139.24 (s, C4′ bpy), 139.06 (s, C4 bpy), 136.46 (s, C6 C6H4),
131.97 (s, C5 C6H4), 128.30 (s, C3 C6H4), 126.81 (b s, C5 and
5′ bpy), 124.02 (s, C4 C6H4), 122.40 (s, C3 bpy), 121.67 (s, C3′
bpy). IR (cm-1): ν(CO) 1682 (Nujol).
C
13H20BrN3Pd: C, 38.59; H, 4.98; N, 10.38. Found: C, 38.67;
1
H, 4.84; N, 9.91. H NMR (200 MHz, CDCl3): δ 7.40 (dd, 1H,
H6, 3J HH ) 8 Hz, 4J HH ) 1 Hz), 7.34 (dd, 1H, H3, 3J HH ) 8 Hz,
4J HH ) 2 Hz), 7.13 (td, 1H, H5, J HH ) 8 Hz, J HH ) 2 Hz),
3
4
3
4
6.91 (td, 1H, H4, J HH ) 8 Hz, J HH ) 1 Hz), 3.0-2.3 (m, 4H,
2 × CH2), 2,74 (s, 3H, Me), 2.66 (s, 3H, Me), 2.56 (s, 3H, Me),
2.46 (s, 3H, Me). 13C NMR (50 MHz, d6-CDCl3): δ 156.05 (s,
CPd), 136.27 (s, C6), 131.63 (s, C3), 129.66 (s, C5), 123.00 (s,
C4), 122.03 (s, CN), 119.62 (s, CCN), 62.45 (s, CH2), 58.34 (s,
CH2), 51.13 (s, Me), 49.78 (s, Me), 48.87 (s, Me), 47.94 (s, Me).
IR (cm-1): ν(CN) 2214 (Nujol).
Syn th esis of [P d {C6H4(CHO)-2}Br (tm ed a )] (2b′): as
described for 2b, from “Pd(dba)2” (150 mg, 0.26 mmol), tmeda
(N,N,N′,N′-tetramethylethylenediamine; 39 µL, 0.26 mmol),
and 2-bromobenzaldehyde (45 µL, 0.39 mmol). Color: yellow.
Yield: 76 mg, 72%. Mp: 181 °C dec. Anal. Calcd for C13H21
-
BrN2OPd: C, 38.31; H, 5.19; N, 6.87. Found: C, 38.51; H, 5.23;
N, 6.89. 1H NMR (200 MHz, CDCl3): δ 11.07 (s, 1H, CHO),
7.66 (dd, 1H, H3, 3J HH ) 7 Hz, 4J HH ) 2 Hz), 7.61 (dd, 1H, H6,
3J HH ) 7 Hz, 4J HH ) 1 Hz), 7.16 (td, 1H, H5, 3J HH ) 7 Hz, 4J HH
Syn t h esis of [P d {C6H 4(CHdCH 2)-2}(b p y)(P P h 3)]TfO
(3a ). TlOTf (TfO ) CF3SO3; 65 mg, 0.18 mmol) and bpy (29
mg, 0.18 mmol) were added to a solution of 1a (150 mg, 0.18
mmol) in dichloromethane (15 mL), and the mixture was
3
) 2 Hz), 7.00 (b t, 1H, H4, J HH ) 7 Hz), 3.0-2.3 (m, 4H, 2 ×

Pd Complexes with Functionalized Aryl Ligands
Organometallics, Vol. 19, No. 5, 2000 755
°C dec. NMR: not sufficiently soluble. Anal. Calcd for (C25H19
stirred at room temperature overnight. The suspension was
filtered over Celite, the solution evaporated to dryness, and
the residue triturated with diethyl ether to give 3a as a yellow
solid. Yield: 124 mg, 88%. Mp: 156 °C dec. ΛM (acetone): 116
Ω-1 cm2 mol-1. Anal. Calcd for C37H30F3N2O3PdS: C, 57.19;
H, 3.89; N, 3.60; S, 4.13. Found: C, 57.25; H, 3.81; N, 3.46; S,
-
BrOPPd)2: C, 54.53; H, 3.48; N, 2.54. Found: C, 54.17; H, 3.34;
N, 2.55. IR (cm-1): ν(CN) 2220 (Nujol).
Syn th esis of [P d 2(µ-Br )2{C6H4(CN)-2}2{P (o-To)3}2] (5d ′′).
“[Pd(dba)2]” (200 mg, 0.35 mmol) and P(o-To)3 (107 mg, 0.35
mmol) were mixed in toluene (20 mL) under nitrogen. Then,
2-bromobenzonitrile (95 mg, 0.52 mmol) was added, and the
resultant suspension was slowly heated until the red color
disappeared (25 min, 80 °C). The solvent was evaporated under
vacuum, the residue was extracted with dichloromethane (4
× 10 mL), the combined extracts were filtered over Celite, and
the resulting solution was evaporated in vacuo. Addition of
diethyl ether (15 mL) precipitated a solid which was filtered,
washed with diethyl ether, and air-dried to give 5d ′′ as a yellow
solid. Yield: 47 mg, 23%. Mp: 300 °C dec. NMR: not
sufficiently soluble. Anal. Calcd for (C28H25BrNPPd)2: C, 56.73;
H, 4.25; N, 2.36. Found: C, 56.70; H, 4.55; N, 2.39. IR (cm-1):
ν(CN) 2214 (Nujol).
1
3
3.89. H NMR (300 MHz, CDCl3): δ 8.79 (d, 1H, bpy, J HH
)
8 Hz), 8.24-8.14 (m, 1H), 7.72-6.72 (several m, 26H), 5.46
3
2
(dd, 1H, CHdCH2 H trans to H, J HH ) 18 Hz, J HH ) 1 Hz),
3
2
5.04 (dd, 1H, CHdCH2 H cis to H, J HH ) 11 Hz, J HH ) 1
Hz). 31P NMR (121 MHz, CDCl3): δ 32.61 (s).
Syn th esis of [P d{K2-C,O-C6H4{C(O)Me}-2}(bpy)]TfO (4c).
TlOTf (46 mg, 0.13 mmol) was added to 1c (60 mg, 0.13 mmol)
in acetone (17 mL), and the mixture was stirred for 1 h. The
suspension was filtered over Celite and the resulting solution
evaporated to dryness. Addition of diethyl ether causes the
precipitation of a solid, which was filtered, washed with diethyl
ether, and dried to give 4c as a yellow solid. Yield: 60 mg,
87%. Mp: 172 °C dec. ΛM (acetone): 150 Ω-1 cm2 mol-1
NMR: not sufficiently soluble. Anal. Calcd for C19H15F3N2O3-
PdS: C, 42.99; H, 2.85; N, 5,28; S, 6.04. Found: C, 42.68; H,
2.95; N, 5.29; S, 5.82. IR (cm-1): ν(CdO) 1582 (Nujol).
.
Syn th esis of [P d {K2-C,O-C6H4{C(O)Me}-2}Br {P (o-To)3}]
(6c′′). “[Pd(dba)2]” (200 mg, 0.35 mmol) and P(o-To)3 (107 mg,
0.35 mmol) were mixed in toluene (20 mL) under nitrogen.
Then, 2-bromoacetophenone (70 µL, 0.52 mmol) was added,
and the resultant suspension was slowly heated until the red
color disappeared (20 min, 70 °C). The solvent was evaporated
under vacuum, the residue was extracted with dichloro-
methane (4 × 10 mL), the combined extracts were filtered over
Celite, and the resulting solution evaporated under vacuum.
Addition of diethyl ether (15 mL) precipitated a solid which
was filtered, washed with diethyl ether, and air-dried to give
6c′′ as a yellow solid. Yield: 120 mg, 56%. Mp: 205 °C dec.
1H NMR (300 MHz, CDCl3): δ 8.70 (dd, 1H, H6 endo o-To,
Syn th esis of [P d 2(µ-Br )2{C6H4(CHO)-2}2(P P h 3)2] (5b).
[PdCl2(NCPh)2] (48 mg, 0.13 mmol) was added to a dichloro-
methane solution (5 mL) of 1b (200 mg, 0.25 mmol). The
resulting yellow suspension was stirred for 30 min. Then, a
large excess of NaBr (1.03 g, 10 mmol) was added and the
mixture stirred for a further 10 min. The final suspension was
filtered over Celite, the solid was washed with dichloro-
methane (3 × 5 mL), and the combined mother liquors were
concentrated nearly to dryness. Diethyl ether (15 mL) was then
added, precipitating a solid, which was filtered, washed with
diethyl ether, and dried in air to give 5b as a yellow solid.
Yield: 132 mg, 95%. Mp: 212 °C dec. NMR: not sufficiently
soluble. Anal. Calcd for C50H40Br2O2P2Pd2: C, 54.23; H, 3.64.
Found: C, 53.90; H, 3.34. IR (cm-1): ν(CdO) 1692 (Nujol).
Syn t h esis of [P d 2(µ-Br )2{C6H 4(CH O)-2}2{P (o-To)3}2]
(5b′′). “Pd(dba)2” (150 mg, 0.26 mmol) and P(o-To)3 (79 mg,
0.26 mmol) were mixed in toluene (20 mL) under nitrogen.
After 10 min, 2-bromobenzaldehyde (45 µL, 0.39 mmol) was
added and the mixture slowly heated until the red color
disappeared (45 min, 80 °C). The solvent was evaporated under
vacuum, the resulting residue was extracted with dichloro-
methane (4 × 10 mL), and the combined extracts were filtered
over anhydrous MgSO4. The resultant yellow solution was
evaporated to dryness and diethyl ether added, precipitating
a solid which was filtered, washed with diethyl ether, and air-
dried to give 5b′′ as a yellow solid. Yield: 82 mg, 53%. Mp:
210 °C dec. Anal. Calcd for (C28H26BrOPPd)2: C, 56.45; H, 4.40.
Found: C, 56.54; H, 4.14. 1H NMR (300 MHz, CDCl3, -60
3
3J PH ) 18 Hz, J HH ) 8 Hz), 7.5-7.1 (several m, 11H), 6.98 (t,
1H, J HH ) 7 Hz), 6.76 (t, 1H, J HH ) 7 Hz), 6.49 (t, 1H, J HH
)
7 Hz), 3.27 (s, 3H, Me), 2.71 (s, 3H, COMe), 2.09 (s, 3H, Me),
1.68 (s, 3H, Me). 31P NMR (121 MHz, CDCl3): δ 38.37 (s). Anal.
Calcd for C29H28BrOPPd: C, 57.12; H, 4.63. Found: C, 57.14;
H, 4.69. IR (cm-1): ν(CdO) 1586 (Nujol).
Syn th esis of In d en ols 7 a n d 8. PhCtCPh (157 mg, 0.88
mmol) or EtCtCEt (0.1 cm3, 0.88 mmol) and TlOTf (156 mg,
0.44 mmol) were added to a solution of 2c (200 mg, 0.44 mmol)
in 15 cm3 of CH2Cl2. The resulting suspension was stirred for
16 h at room temperature and then filtered over Celite. The
red solution obtained was concentrated and chromatographed
over silica gel containing a small amount of silica gel 60 GF254,
using 1:2 hexane/CH2Cl2 as eluant. The first, colorless band
was taken. The product was extracted with acetone, stirred
with anhydrous MgSO4, and filtered. Evaporation of the
acetone gave 7 or 8 as a white solid. Yield: 92 mg, 70% (7); 60
mg, 67% (8). The NMR data of these indenols coincide with
those reported in the literature.33
X-r a y St r u ct u r e Det er m in a t ion s. Com p ou n d s 1b ‚
CH2Cl2 a n d 6c′′. Da ta Collection a n d Red u ction . Crystals
were mounted in inert oil on glass fibers and transferred to
the cold gas stream of the diffractometer (Bruker SMART 1000
CCD with LT-3 low-temperature apparatus). Measurements
were conducted using monochromated Mo KR radiation (ω-
scans). Absorption corrections were based on multiple scans
(program SADABS).
Str u ctu r e Refin em en t. Structures were refined anisotro-
pically against F2 (program SHELXL-97, G. M. Sheldrick,
University of Go¨ttingen). H atoms were included using a riding
model or with rigid methyl groups. Special aspects: for 1b‚
CH2Cl2 the dichloromethane molecule is disordered over an
inversion center.
Com p ou n d s 1a ‚2CH2Cl2, 2b, a n d 2d . Da ta Collection
a n d Red u ction . Crystals were mounted on glass fibers and
transferred to the diffractometer as summarized in Table 1.
Cell constants were refined from ca. 60 reflections in the 2θ
3
°C): δ 11.60 (bs, 1H, CHO), 9.59 (dd, 1H, H6 o-To endo, J PH
3
) 19 Hz, J HH ) 7 Hz), 7.9-6.5 (several m, 15H), 3.61 (s, 3H,
Me), 1.46 (s, 3H, Me), 0.91 (s, 3H, Me). 31P NMR (121 MHz,
CDCl3, -60 °C): δ 27.83 (s). IR (cm-1): ν(CdO) 1682 (Nujol).
Syn t h esis of [P d 2 (µ-Br )2{C6H 4{C(O)Me}-2}2(P P h 3)2]
(5c). Complex 5c was prepared as described for 5b from 1c
(350 mg, 0.42 mmol) and [PdCl2(NCPh)2] (81 mg, 0.21 mmol).
Since the elemental analyses were unsatisfactory, the resulting
solid was applied to a preparative TLC and eluted with hexane/
dichloromethane (1:3). The immobile fraction was collected to
give pure 5c as a yellow solid. Yield: 174 mg, 73%. Mp: 195
°C dec. Anal. Calcd for C52H44Br2O2P2Pd2: C, 55.01; H, 3.91.
Found: C, 54.83; H, 3.96. 1H NMR (300 MHz, CDCl3, -60
°C): δ 7.8-7.2 (several m, 16H), 7.08 (t, 1H, C6H4, J HH ) 7
Hz), 6.83 (t, 1H, C6H4, J HH ) 7 Hz), 6.38 (t, 1H, C6H4, J HH
)
7 Hz), 2.81 (s, 3H, Me). 31P NMR (121 MHz, CDCl3, -60 °C):
δ 49.64 (s). IR (cm-1): ν(CdO) 1660 (Nujol).
Syn t h esis of [P d 2(µ-Br )2{C6H4(CN)-2}2(P P h 3)2] (5d ).
Complex 5d was prepared by following the procedure described
for 5b from 1d (200 mg, 0.25 mmol) and [PdCl2(NCPh)2] (47
mg, 0.12 mmol). Color: yellow. Yield: 118 mg, 87%. Mp: 228
(33) Liebeskind, L. S.; Gasdaska, J . R.; McCallum, J . S.; Tremont,
S. J . J . Org. Chem. 1989, 54, 669.

756 Organometallics, Vol. 19, No. 5, 2000
Ta ble 1. Cr ysta l Da ta for 1a ‚2CH2Cl2, 1b‚CH2Cl2, 2b, 2d , a n d 6c′′
Vicente et al.
1a ‚2CH2Cl2
1b‚CH2Cl2
2b
2d
6c′′
formula
Mr
C
46H41BrCl4P2Pd
C43.5H36BrClOP2Pd
858.42
C17H13BrN2OPd
447.61
C17H12BrN3Pd
444.61
C29H28BrOPPd
609.79
959.88
source
vapor diffusion
hexane/CH2Cl2
colorless prism
monoclinic
11.7835(14)
28.951(2)
12.9176(14)
99.891(8)
4341.3
liquid diffusion
hexane/CH2Cl2
colorless block
monoclinic
11.7883(10)
18.9947(16)
16.7519(16)
102.731(3)
3658.8
liquid diffusion
hexane/CH2Cl2
yellow prism
monoclinic
9.6853(9)
13.5645(13)
11.6714(12)
91.354(6)
1532.9
liquid diffusion
hexane/CH2Cl2
yellow lath
monoclinic
9.8692(12)
13.799(2)
11.7476(14)
91.574(10)
1599.3
liquid diffusion
hexane/CH2Cl2
pale yellow tablet
orthorhombic
17.9750(14)
12.9761(10)
21.532(2)
90
cryst habit
cryst syst
a, Å
b, Å
c, Å
â, deg
V, Å3
5022.3
Z
4
4
4
4
8
radiation used
λ, Å
T, K
Mo KR
0.710 73
173(1)
Mo KR
0.710 73
143
Mo KR
0.710 73
173(1)
Mo KR
0.710 73
293(2)
Mo KR
0.710 73
143
monochromator
space group
cryst size, mm
µ, mm-1
graphite
P21/n
graphite
P21/c
graphite
P21/n
graphite
P21/n
graphite
Pbca
0.45 × 0.32 × 0.28
0.33 × 0.20 × 0.17
0.60 × 0.20 × 0.14
0.42 × 0.20 × 0.14
0.20 × 0.17 × 0.06
1.70
1.79
3.82
3.66
2.41
abs cor
ψ scans
0.91
0.75
Siemens P4
ω
6-50
-h, -k, (l
9239
7642
0.032
0.040
0.069
0.53
SADABS
0.94
0.67
ψ scans
0.98
0.74
Siemens P4
ω
6-50
(h, -k, -l
2873
2693
0.023
0.031
0.062
0.51
ψ scans
0.86
0.70
Siemens P4
ω
6-50
(h, -k, -l
3910
2758
0.020
0.029
0.055
0.33
SADABS
0.99
0.73
max transmissn, %
min transmissn, %
diffractometer
scan method
2θ range, deg
hkl limits
no. of rflns measd
no. of indep rflns
Rint
Bruker SMART
ω
Bruker SMART
ω
3.4-60
3.8-60
(h, (k, +l
(h, (k, +l
25 949
39 959
10 584
0.029
0.033
0.086
7321
0.079
0.030
0.053
R1a
wR2b
max ∆F, e Å-3
1.46
0.52
R1 ) ∑||Fo| - |Fc||/∑|Fo| for reflections with I > 2σ(I). wR2 ) [∑[w(Fo - Fc2)2/∑[w(Fo2)2]]0.5 for all reflections; w-1 ) σ2(F2) + (aP)2
a
b
2
+ bP, where P ) (2Fc + Fo2)/3 and a and b are constants set by the program.
2
range 10-25°. The structure of 2b was solved by direct
methods, and the others were solved by the heavy-atom
method and subjected to anisotropic full-matrix least-squares
refinement against F2 (program SHELXL-93, G. M. Sheldrick,
University of Go¨ttingen). H atoms were included using a riding
model. For 1a ‚2CH2Cl2 the final R(F) (I > 2σ(I)) was 0.0403,
for 487 parameters and 426 restraints; maximum ∆/σ ) 0.001.
For compound 2b the final R(F) (I > 2σ(I)) was 0.0310, for
199 parameters and 175 restraints; maximum ∆/σ ) 0.001.
For compound 2d the final R(F) (I > 2σ(I)) was 0.0290, for
199 parameters and 175 restraints; maximum ∆/σ ) 0.001.
Restraints were applied to local symmetry, and U components
of neighboring light atoms. The programs use the neutral atom
scattering factors, ∆f ′ and ∆f ′′ values, and absorption coef-
ficients from ref 34.
Brief refluxing in toluene (10 min) of a mixture of “Pd-
(dba)2”, PR3, and 2-bromostyrene in an 1:2:1.5 molar
ratio led to the complexes trans-[Pd(C6H4X-2)Br(PR3)2]
(X ) CHdCH2, R ) Ph (1a ), p-To ()4-tolyl) (1a ′))
(Scheme 1). Attempts to prepare 1a under other reaction
conditions (shorter reaction time or lower temperature)
gave irresolvable mixtures. Complex 1a can also be
obtained by using [Pd(PPh3)4] instead of the mixture
“Pd(dba)2” + PR3.
Similar reactions in the presence of nitrogen donor
ligands such as 2,2′-bipyridine (bpy) and N,N,N′,N′-
tetramethylethylenediamine (tmeda) lead to decomposi-
tion. A somewhat different behavior was observed with
2-bromobenzaldehyde, 2-bromoacetophenone, and 2-bro-
mobenzonitrile. The reactions in the presence of PPh3
were successful, yielding trans-[Pd(C6H4X-2)Br(PR3)2]
(R ) Ph, X ) CHO (1b), C(O)Me (1c), CN (1d )), as were
those using bpy or tmeda, giving the complexes cis-[Pd-
(C6H4X-2)Br(L2)] (L2 ) bpy, X ) CHO (2b), C(O)Me (2c),
CN (2d ); L2 ) tmeda, X ) CHO (2b′), CN (2d ′)). It was
not possible to obtain the complex [Pd(C6H4C(O)Me-2)-
Br(tmeda)].
Resu lts a n d Discu ssion
Syn th esis of Com p lexes. We have prepared the
complexes 1, 2, 5b′′, 5d ′′, and 6c′′ by oxidative addition
of the corresponding aryl bromides to [Pd2(dba)3]‚dba
(“Pd(dba)2”) in the presence of a stoichiometric amount
of the ligand (Scheme 1). Such a procedure has been
shown to be useful for the synthesis of organopalladium
complexes containing nitrogen35,36 or phosphorus donor
ligands,37 and we have recently applied it to the
synthesis of palladated o-aniline derivatives.14
When complex 1a is reacted with bpy in the presence
of TlOTf, the cationic complex 3a is formed. The
cyclopalladated cation 4c can be obtained from the
reaction of 2c with TlOTf. A similar reaction with 2b
gave a product that we could not characterize.
The complexes [Pd(Ar)(µ-X)]2 (X ) Cl, AcO), obtained
by cyclometalation of ArH, have been used in most
alkyne,7,10,13,38-50 in some isocyanide,51-56 and in a few
(34) International Tables for Crystallography; Kluwer Academic
Publishers: Dordrecht, The Netherlands, 1992; Vol. C, Tables 6.1.1.4
(pp 500-502), 4.2.6.8 (pp 219-222), and 4.2.4.2 (pp 193-199).
(35) van Asselt, R.; Vrieze, K.; Elsevier: C. J . J . Organomet. Chem.
1994, 480, 27.
(36) Markies, B. A.; Canty, A. J .; Degraaf, W.; Boersma, J .; J anssen,
M. D.; Hogerheide, M. P.; Smeets, W. J . J .; Spek, A. L.; van Koten, G.
J . Organomet. Chem. 1994, 482, 191.
(38) Dupont, J .; Pfeffer, M. J . Organomet. Chem. 1987, 321, C13.
(39) Pfeffer, M.; Rotteveel, M. A.; Sutter, J .-P.; De Cian, A.; Fisher,
J . J . Organomet. Chem. 1989, 371, C21.
(37) Wallow, T. I.; Goodson, F. E.; Novak, B. M. Organometallics
1996, 15, 3708.

Pd Complexes with Functionalized Aryl Ligands
Organometallics, Vol. 19, No. 5, 2000 757
Sch em e 1
(C6H4X-2)(µ-Br)(PR3)]2. The involvement of this type of
complex in palladium-catalyzed C-N bond formation
reactions has been shown.3,57-60 We attempted the
oxidative addition of the corresponding bromoarenes to
a mixture of Pd(dba)2 and PPh3 in a 1:1 molar ratio but
observed only the formation of the monomeric complexes
1b-d in low yields. In the case of the reaction with
2-bromostyrene, the resonances due to the vinyl group
were not present in the 1H NMR spectrum of the
product of the reaction. Nevertheless, it was possible
to prepare the desired complexes [Pd(C6H4X-2)(µ-Br)-
(PPh3)]2 (X ) CHO (5b), C(O)Me (5c), CN ) (5d ))
(Scheme 1) by reacting 1b-d with [PdCl2(NCPh)2],
following a procedure described for the synthesis of some
PhCH2C(O)[Pd] derivatives.61 Again, the attempts to
prepare 5a through this method led to products without
the vinyl group. This behavior is probably the result of
the interchange between a phenyl group of PPh3 and
the aryl ligand, which is a very well-known process.62-67
In contrast, the homologous complexes [Pd(C6H4X-2)-
(µ-Br){P(o-To)3}]2 (X ) CHO (5b′′), CN ) (5d ′′)) were
prepared by oxidative addition reactions of BrC6H4X-2
to [Pd(P(o-To)3)2]57,68,69 or to Pd(dba)2 in the presence
of 1 equiv of P(o-To)3.60 In the case of X ) C(O)Me, the
monomer [Pd{κ2-C,O-C6H4{C(O)Me}-2}Br{P(o-To)3}]
(6c′′), containing a C,O chelate ring instead of a bromo
bridging ligand, was obtained, as confirmed by an X-ray
diffraction study (see below and Scheme 1). We had
already observed the coordination ability of this sub-
stituent in (6-acetyl-2,3,4-trimethoxyphenyl)palladium
complexes.17
The complex 2c reacts with the alkyne PhCtCPh or
EtCtCEt and TlOTf to give 1-methyl-2,3-diphenyl-1H-
indenol (7) or 1-methyl-2,3-diethyl-1H-indenol (8), re-
spectively. The syntheses of these compounds were
previously achieved by reacting ortho-manganated ac-
etophenone with trimethylamine N-oxide and the cor-
responding alkynes.33
(50) Tao, W.; Silverberg, L. J .; Rheingold, A. L.; Heck, R. F.
Organometallics 1989, 8, 2550.
(51) O’Sullivan, R. D.; Parkins, A. W. J . Chem. Soc., Chem. Commun.
1984, 1165.
(52) Dupont, J .; Pfeffer, M. J . Chem. Soc., Dalton Trans. 1990, 3193.
(53) van Baar, J . F.; Klerks, J . M.; Overbosch, P.; Stufkens, D. J .;
Vrieze, K. J . Organomet. Chem. 1976, 112, 95.
(54) Yamamoto, Y.; Yamazaki, H. Synthesis 1976, 750.
(55) Albinati, A.; Pregosin, P. S.; Ru¨edi, R. Helv. Chim. Acta 1985,
68, 2046.
(56) Gehrig, K.; Klaus, A. J .; Rys, P. Helv. Chim. Acta 1983, 66,
2603.
(57) Paul, F.; Patt, J .; Hartwig, J . F. Organometallics 1995, 14, 3030.
(58) Hartwig, J . F.; Richards, S.; Baranano, D.; Paul, F. J . Am.
Chem. Soc. 1996, 118, 3626.
CO51,52 insertion reactions. Therefore, for a future study
of the reactivity of these arylpalladium complexes, we
considered it of interest to synthesize the complexes [Pd-
(59) Louie, J .; Paul, F.; Hartwig, J . F. Organometallics 1996, 15,
2794.
(60) Widenhoefer, R. A.; Zhong, H. A.; Buchwald, S. L. Organome-
tallics 1996, 15, 2745 and references therein.
(61) Lin, Y. S.; Yamamoto, A. Organometallics 1998, 17, 3466.
(62) Herrmann, W. A.; Brossmer, C.; Priermeier, T.; Ofele, K. J .
Organomet. Chem. 1994, 481, 97.
(63) Goodson, F. E.; Wallow, T. I.; Novak, B. M. J . Am. Chem. Soc.
1997, 119, 12441.
(64) Sakamoto, M.; Shimizu, I.; Yamamoto, A. Chem. Lett. 1995,
1101 and references therein.
(40) Albert, J .; Granell, J .; Sales, J .; Solans, X. J . Organomet. Chem.
1989, 379, 177.
(41) Ryabov, A. D. Synthesis 1985, 233.
(42) Maassarani, F.; Pfeffer, M.; Spencer, J .; Wehman, E. J . Orga-
nomet. Chem. 1994, 466, 265.
(43) Lopez, C.; Solans, X.; Tramuns, D. J . Organomet. Chem. 1994,
471, 265.
(44) Pfeffer, M. Pure Appl. Chem. 1992, 64, 335.
(45) Sutter, J . P.; Pfeffer, M.; Decian, A.; Fischer, J . Organometallics
1992, 11, 386.
(46) Spencer, J .; Pfeffer, M.; Decian, A.; Fischer, J . J . Org. Chem.
1995, 60, 1005.
(47) Ryabov, A. D.; Vaneldik, R.; Leborgne, G.; Pfeffer, M. Organo-
metallics 1993, 12, 1386.
(65) Segelstein, B. E.; Butler, T. W.; Chenard, B. L. J . Org. Chem.
1995, 60, 12.
(66) Morita, D. K.; Stille, J . K.; Norton, J . R. J . Am. Chem. Soc. 1995,
117, 8576.
(48) Spencer, J .; Pfeffer, M.; Kyritsakas, N.; Fischer, J . Organome-
tallics 1995, 14, 2214.
(49) Zhao, G.; Wang, Q. G.; Mak, T. C. W. Tetrahedron: Asymmetry
1998, 9, 2253.
(67) Kong, K. C.; Cheng, C. H. J . Am. Chem. Soc. 1991, 113, 6313.
(68) Paul, F.; Patt, J .; Hartwig, J . F. J . Am. Chem. Soc. 1994, 116,
5969.
(69) Hartwig, J . F.; Paul, F. J . Am. Chem. Soc. 1995, 117, 5373.

758 Organometallics, Vol. 19, No. 5, 2000
Vicente et al.
F igu r e 1. Section of the HMBC spectrum of 2d ′, showing
long-range correlations between the 13C signals and the
protons of the aryl ligand.
F igu r e 2. Section of the phase-sensitive 1H-NOESY
spectrum of 2b′, showing exchange cross-peaks among all
the methyl groups of the tmeda. The methylene groups are
also in mutual exchange.
Sp ect r oscop ic P r op er t ies of Com p lexes. The
NMR spectra of complexes are in accord with their
proposed geometries in Scheme 1. A noteworthy feature
of the tmeda complexes 2b′,d ′ is that they show four
resonances corresponding to the Me groups of the tmeda
ligand, which indicates a hindered rotation of the aryl
groups around the C-Pd bond.9,19,70 The presence of the
vinyl substituent in complexes 1a ,a ′ and 3a is confirmed
in their 1H NMR spectra, which show the signals
corresponding to this group with coupling constants of
17-18 (trans), 11 (cis), and 1 (gem) Hz. The formyl
derivatives show in their 1H NMR spectra a singlet,
assignable to the proton of the formyl group, whose
position in 1b (9.69 ppm) is quite different from that in
2b, 2b′, and 5b′′ (11.1-11.6 ppm). Probably, in 1b the
magnetic anisotropy induced by one phenyl group of the
PPh3 ligands is responsible for the shielding of the
formyl proton (see X-ray Crystal Structures). This
difference is not as marked in the 13C NMR spectra
(194.54-196.99 ppm). In 2b,b′,c,d ,d ′, the complete
assignment of the NMR resonances of the aryl group
has been achieved using 13C,1H one-bond and long-range
correlations. As an example, Figure 1 is a section of the
HMBC (heteronuclear shift correlations via multiple
bond connectivities) spectrum of 2d ′, showing long-range
correlations between the 13C signals and the protons of
the aryl ligand. These correlations arise from three-bond
spin-spin interactions. The CN carbon can be easily
distinguished from C-2 because it correlates with just
one hydrogen, H-3, while C-2 shows cross-peaks with
both H-6 and H-4. In this way, the aryl protons can be
fully assigned. Furthermore, it is possible to identify
C-3, -4, -5, and -6 from their respective interactions with
H-5, -6, -3, and -4. C-1 shows the two expected cross-
peaks with H-3 and -5.
1H NMR spectrum shows the expected signals of the
halves of the bpy. The behavior of 5c is more complex,
1
since its H and 31P NMR spectra show broad signals
corresponding to both the aryl and the PPh3 ligands;
lowering the temperature to -60 °C causes the sharp-
ening of all signals to give the expected spectra. In 2b′,
a slow fluxional process exchanges all methyl protons
of the tmeda ligand (as well as the methylene protons),
as shown by its phase-sensitive NOESY spectrum (see
Figure 2). In the phase-sensitive NOESY spectrum of
2b we also observed an exchange of the halves of the
bpy. Because these four complexes have a carbonylic
function in the ortho position of the aryl ligand, we
suggest that such fluxional processes involve intermedi-
ates in which a change in the coordination mode of the
aryl group from monocoordinate to chelate occurs. Such
intermediates could be pentacoordinate species and/or
square-planar complexes resulting from displacement
of the Br ligand to give complexes related to 6c′′. The
latter probably exists only in the monomeric form due
to steric reasons. The role played by the oxygen in the
above fluxional processes seems to be confirmed by the
fact that, in the phase-sensitive NOESY spectrum of 2d ′,
the exchange in the tmeda ligand, observed in 2b′, is
not detected.
The 1H NMR of complex 5b′′ shows three broad
signals attributable to the methyl groups of P(o-To)3.
At -60 °C these signals appear as sharp peaks at 3.61,
1.46, and 0.91 ppm, indicating that rotation around the
P-C bonds is hindered; two isomers, exo3 (with the three
tolyl groups in exo positions) and exo2 (with one tolyl
group in an endo position), are accessible, but only the
latter is formed. This is confirmed by the presence of a
doublet of doublets at 9.59 ppm, assignable to the H6
of the endo o-To group, which is forced into close
A feature of 2c is that its 1H and 13C NMR room-
temperature spectra show a broadening of the signals
corresponding to the bpy ligand, whereas the resonances
of the aryl ligand appear as sharp signals. The -60 °C
2
proximity to the palladium dz orbital. A similar behav-
ior has been observed by Hartwig et al.;60 however, in
our case, the P-Pd bond seems to rotate freely and the
three possible rotamers are not observed. Complex 6c′′
(70) Brown, J . M.; Perez-Torrente, J . J .; Alcock, N. W.; Clase, H. J .
Organometallics 1995, 14, 207.

Pd Complexes with Functionalized Aryl Ligands
Organometallics, Vol. 19, No. 5, 2000 759
F igu r e 3. Thermal ellipsoid plot of 1a ‚2CH2Cl2 (50%
probability levels) with the labeling scheme. H atoms and
solvent are omitted for clarity. Selected bond lengths (Å)
and angles (deg): Pd-C(1) ) 2.015(4), Pd-P(1) ) 2.3339-
(11), Pd-P(2) ) 2.3266(11), Pd-Br ) 2.5462(5), C(2)-C(7)
) 1.461(5), C(7)-C(8) ) 1.321(6); C(1)-Pd-P(1) ) 87.36-
(11), C(1)-Pd-P(2) ) 87.68(11), P(1)-Pd-P(2) ) 174.98-
(4), C(1)-Pd-Br ) 174.45(12), P(1)-Pd-Br ) 94.64(3),
P(2)-Pd-Br ) 90.23(3), C(2)-C(7)-C(8) ) 127.3(4).
F igu r e 4. Thermal ellipsoid plot of 1b‚CH2Cl2 (50%
probability levels) with the labeling scheme. The solvent
is omitted for clarity. Selected bond lengths (Å) and angles
(deg): Pd-C(11) ) 1.991(2), Pd-P(1) ) 2.3217(6), Pd-P(2)
) 2.3243(6), Pd-Br ) 2.5029(3), O-C(17) ) 1.212(3);
C(11)-Pd-P(1) ) 87.97(7), C(11)-Pd-P(2) ) 86.94(7),
P(1)-Pd-P(2) ) 173.89(2), C(11)-Pd-Br ) 174.43(7),
P(1)-Pd-Br ) 92.097(17), P(2)-Pd-Br ) 92.640(17),
O-C(17)-C(12) ) 126.5(2).
shows a similar pattern, while 5d ′′ is not soluble enough
for an NMR study.
The IR bands assignable to the ν(CO) mode in 1b,
2b,b′, 5b,b′′, 1c, 2c, and 5c appear in the 1650-1680
cm-1 region in the solid state, indicating the noncoor-
dination of the carbonyl group in these complexes. In
the case of 1b, several bands in the 1650-1680 cm-1
region are probably attributable to a solid-state effect,
since its IR spectrum recorded in dichloromethane
solution shows a single band at 1684 cm-1. The com-
pounds 2b,b′ and 5b,b′′ show only one band in the
1682-1692 cm-1 region in the solid state. Complexes
4c and 6c′′ have this absorption at lower frequency
(1582, 1586 cm-1), which is in accordance with the
proposed formulations as C,O palladacycles.
F igu r e 5. Thermal ellipsoid plot of 2b (50% probability
levels) with the labeling scheme. Selected bond lengths (Å)
and angles (deg): Pd-C(11) ) 1.986(4), Pd-N(1) ) 2.060-
(3), Pd-N(2) ) 2.108(3), Pd-Br ) 2.4207(6), O-C(17) )
1.204(5); C(11)-Pd-N(1) ) 95.8(2), C(11)-Pd-N(2) )
174.1(2), N(1)-Pd-N(2) ) 79.18(13), C(11)-Pd-Br )
88.96(11), N(1)-Pd-Br ) 173.79(9), N(2)-Pd-Br ) 96.28-
(9), O-C(17)-C(12) ) 127.3(4).
The ν(CtN) IR bands of the cyanophenyl complexes
appear in the region 2212-2220 cm-1
.
X-r a y Cr ysta l Str u ctu r es. The crystal and molec-
ular structures (Table 1) of the complexes 1a ‚2CH2Cl2
(Figure 3) 1b ‚CH2Cl2 (Figure 4), 2b (Figure 5), 2d
(Figure 6), and 6c′′ (Figure 7) have been determined by
X-ray diffraction studies. All these complexes show
somewhat distorted square planar coordination (mean
deviations from the best plane through Pd and the four
donor atoms are 0.04, 0.03, 0.06, 0.04, and 0.08 Å,
respectively). The distortion may be associated in ap-
propriate cases with the chelating nature of the bpy or
the aryl ligand (in 6c′′ C(11) lies 0.3 Å out of the plane
of Pd, O, P, and Br; mean deviation 0.02 Å).
The Pd-C bond distance in the C6H4(CHdCH2)-2
complex 1a ‚2CH2Cl2 is significantly longer (2.015(4) Å)
than that in the C6H4(CHO)-2 complex 1b‚CH2Cl2
(1.991(2) Å), despite the otherwise identical ligands. The
Pd-C bond distances in the bpy complexes 2b and 2d
(1.986(4) Å) are similar to those in 1b‚CH2Cl2, in turn
showing the similarity of (i) bond strength from Pd to
the C6H4(CHO)-2 and C6H4(CN)-2 aryl ligands and (ii)
trans influence of the Br and bpy ligands. The Pd-C
bond distance in the C6H4{C(O)Me}-2 complex 6c′′
(2.021(2) Å) is similar to that in 1a ‚2CH2Cl2.
The Pd-Br bond lengths follow the order 1a ‚2CH2-
Cl2 (2.5462(5) Å) > 6c′′ (2.5085(3) Å) ≈ 1b‚CH2Cl2
(2.5029(3) Å) > 2b (2.4207(6) Å) > 2d (2.4127(6) Å),
showing the scale of trans influence: C6H4(CHdCH2)-2
> C6H4{C(O)Me}-2 ≈ C6H4(CHO)-2 . bpy. The short-
ening of the Pd-Br bond in 2d with respect to 2b could
be associated with the intermolecular hydrogen bond
between the bromo ligand and H(11A) of the bpy ligand
in 2d (see below). The Pd-N bond distances in com-
plexes 2b (Pd-N trans to aryl, 2.108(3) Å; Pd-N trans
to Br, 2.060(3) Å) and 2d (Pd-N trans to aryl, 2.112(3)
Å; Pd-N trans to Br, 2.056(3) Å) show the scale of trans
influence: C6H4(CHO)-2 ) C6H4CN-2 . bpy. The Pd-P

760 Organometallics, Vol. 19, No. 5, 2000
Vicente et al.
F igu r e 6. Thermal ellipsoid plot of 2d (50% probability
levels) with the labeling scheme. Selected bond lengths (Å)
and angles (deg): Pd-C(1) ) 1.986(4), Pd-N(1) ) 2.112-
(3), Pd-N(2) ) 2.056(3), Pd-Br ) 2.4127(6), C(7)-N(3) )
1.140(5); C(1)-Pd-N(1) ) 173.37(13), C(1)-Pd-N(2) )
95.66(13), N(1)-Pd-N(2) ) 79.21(12), C(1)-Pd-Br )
88.76(10), N(1)-Pd-Br ) 96.41(8), N(2)-Pd-Br ) 175.57-
(9), N(3)-C(7)-C(2) ) 179.1(5).
F igu r e 8. Hydrogen bond interactions in 2d .
In the complexes 1b‚CH2Cl2 and 2b, the O atom of the
formyl group makes a short contact of 2.884(2) or 2.982-
(3) Å to the Pd atom, but the CdO bond lengths are
normal (1.212(3) and 1.204(5) Å, respectively). X-ray
diffraction and NMR studies by Pregosin et al. have
shown that, in some (quinoline-8-carbaldehyde)plati-
num complexes, the CHO group interacts with the metal
through the H atom.72,73
In complex 2d , the molecules are connected to form
layers through intermolecular CN‚‚‚H-Cbpy and Br‚‚‚
H-Cbpy hydrogen bonds (N(3)‚‚‚H(9B), 2.51 Å; N(3)‚‚‚
C(9B), 3.243(5) Å; N(3)‚‚‚H(9B)-C(9B), 150°; Br‚‚‚
H(11A), 3.01 Å; Br‚‚‚C(11A), 3.845(4) Å; N(3)‚‚‚H(9B)-
C(9B), 136°). As shown in Figure 8, each molecule uses
its Br and N atoms and the pair of H atoms of the
pyridine ring trans to the aryl ligand, H(9) and H(11),
to form hydrogen bonds with H(11), H(9), N, and Br
atoms, respectively, of four neighboring molecules.
F igu r e 7. Thermal ellipsoid plot of 6c′′ (50% probability
levels) with the labeling scheme. Selected bond lengths (Å)
and angles (deg): Pd-C(11) ) 2.021(2), Pd-O ) 2.1103-
(15), Pd-P ) 2.2546(6), Pd-Br ) 2.5085(3), O-C(17) )
1.242(3); C(11)-Pd-O ) 80.84(8), C(11)-Pd-P ) 95.81-
(7), O-Pd-P ) 175.11(5), C(11)-Pd-Br ) 166.03(7),
O-Pd-Br ) 86.96(4), P-Pd-Br ) 96.765(18), C(17)-O-
Pd ) 113.57(15), C(12)-C(17)-O ) 118.5(2).
Ack n ow led gm en t. We thank the DGES (Grant No.
PB97-1047), the Fonds der Chemischen Industrie, and
INTAS for financial support. E.M.-V. and M.C.R.A.
thank the Fundacio´n Se´neca (Comunidad Auto´noma de
la Regio´n de Murcia, Murcia, Spain) and the Ministerio
de Educacio´n y Ciencia of Spain for a grant and a
contract, respectively. We are grateful to Prof. Paul
Pregosin for helpful suggestions and NMR facilities.
bond distances in complexes 1a ‚2CH2Cl2 and 1b‚CH2-
Cl2 (2.3339(11)-2.3217(6) Å) are significantly longer
than in 6c′′ (2.2546(6) Å). With all the above data, the
following scale of trans influence results: C6H4(CHd
CH2)-2 > C6H4{C(O)Me}-2 g C6H4(CHO)-2 ) C6H4CN-2
. bpy ) Br; PPh3 > OdC(Me)C6H4-2.
Su p p or tin g In for m a tion Ava ila ble: Tables giving crys-
tal data and refinement details, atomic coordinates and
thermal parameters, and bond distances and angles for 1a ‚
2CH2Cl2, 1b‚CH2Cl2, 2b, 2d , and 6c′′. This material is avail-
able free of charge via the Internet at http://pubs.acs.org.
The crystal structure of 6c′′ confirms the monomeric
structure proposed for this complex, based on the C,O
chelating nature of the aryl ligand, and also the exo2
conformation of the phosphine deduced by 1H NMR
spectroscopy. The coordination of the carbonylic oxygen
leads to a slight lengthening of the CdO bond (1.242(3)
Å) with respect to the mean value in ketones (1.221 Å).71
OM9905963
(71) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 2 1987, S1.
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P. S. Inorg. Chem. 1987, 26, 503.
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671.