Synthesis and Structure of PdII Complexes Containing the C,C-Chelating Bis-Ylide Ligand [Ph3=C(H)]2CO. X-ray Crystal Structure of {Pd(μ-Cl){[C(H)PPh3]2CO}}2(ClO 4)2·CH

Article abstract of DOI:10.1021/ic980392z

The reaction of Pd(OAc)₂ with the bis(phosphonium) salt [Ph₃PCH₂COCH₂PPh₃]Cl₂ (1:1 molar ratio) results in the formation of the cis-dichlorobis(ylide) derivative Cl₂Pd{[C(H)PPh

Full text of DOI:10.1021/ic980392z

Inorg. Chem. 1998, 37, 6007-6013
6007
Synthesis and Structure of PdII Complexes Containing the C,C-Chelating Bis-Ylide Ligand
[Ph3PdC(H)]2CO. X-ray Crystal Structure of {Pd(µ-Cl){[C(H)PPh3]2CO}}2(ClO4)2‚CH2Cl2
Larry R. Falvello, Susana Ferna´ndez, Rafael Navarro,* Angel Rueda, and
Esteban P. Urriolabeitia
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n, Universidad de
Zaragoza- Consejo Superior de Investigaciones Cient´ıficas, 50009 Zaragoza, Spain
ReceiVed April 7, 1998
The reaction of Pd(OAc)2 with the bis(phosphonium) salt [Ph3PCH2COCH2PPh3]Cl2 (1:1 molar ratio) results in
the formation of the cis-dichlorobis(ylide) derivative Cl2Pd{[C(H)PPh3]2CO}, 1, in which the bis(ylide) ligand
[C(H)PPh3]2CO acts as a chelating group through the two ylide carbon atoms. Complex 1 reacts with TlClO4
(1:1 molar ratio) to give [Pd(µ-Cl){[C(H)PPh3]2CO}]2(ClO4)2, 2, which reacts with two further equivalents of
TlClO4 in NCMe to give [Pd{[C(H)PPh3]2CO}(NCMe)2](ClO4)2 3. The reactivity of 2 and 3 has been explored.
Compound 2 reacts with pyridine, 3,5-lutidine, or Ph3PdC(H)CN (1:2 molar ratio), resulting in the rupture of the
chlorine bridging system and formation of [PdCl{[C(H)PPh3]2CO}(L)](ClO4) (L ) py (4), 3,5-lu (5), NC-C(H)d
PPh3 (6)), and with Tlacac (1:2 molar ratio) with formation of the acetylacetonate [Pd(acac){[C(H)PPh3]2CO}]-
(ClO4), 7. On the other hand, complex 3 reacts with the ylide Ph3PdC(H)CN (1:2 molar ratio) giving
[Pd{[C(H)PPh3]2CO}[NC-C(H)dPPh3]2](ClO4)2, 8, which contains two N-coordinated ylides, and with NBu4-
OH (1:1) to give [Pd(µ-OH){[C(H)PPh3]2CO}]2(ClO4)2, 9. The reaction of Pd(OAc)2 with the ylide phosphonium
salt [Ph3PdC(H)COCH2PPh3](ClO4) (1:1) gives the acetate dimer [Pd(µ-OOCCH3){[C(H)PPh3]2CO}]2(ClO4)2,
10. The structures of complexes 1-10 were deduced from their spectroscopic data and from the resolution of
the molecular structure of complex 2‚CH2Cl2.
Introduction
donor atoms due to its multifuctionality. However, as far as
we know, only one report on this bis-ylide has appeared in the
literature8 (polynuclear gold and silver complexes), and very
few reports of related ylides containing the CCC skeleton have
been published.9,10
In this report we present our first results on the previously
unexplored chemistry of PdII with this bis-ylide. A series of
new complexes with the ylide coordinated as a C,C-chelate are
described, together with the crystal structure of a representative
example.
Ylides of phosphorus are now recognized as a class of
extremely powerful ligands that form complexes with both main
group elements and transition metals.1 In recent papers, we
have described a part of the chemistry of PdII and PtII with
R-stabilized ylides, such as Ph3PdC(H)COR (R ) Me, Ph,
OMe, NMe2) and Ph3PdC(H)CN.2-7 Throughout these studies,
we have observed the ability of these ylides to behave as
ambidentate ligands (except for the NMe2 derivative7). More-
over, we have obtained evidence about the possibility of
controlling the binding modessthat is, given an organometallic
substrate to predict the coordination mode of a given ylide and,
conversely, to design a substrate to drive a given binding mode.
A bis-ylide such as Ph3PdC(H)COC(H)dPPh3 offers new
synthetic possibilities. First, it has three potential coordinating
atoms (two carbons and one oxygen). Second, it can behave
as a chelating or bridging ligand through the same or different
Results and Discussion
The reaction of Pd(OAc)2 with the bis-phosphonium salt [Ph3-
PCH2COCH2PPh3]Cl2 (1:1 molar ratio) in CH2Cl2 at room
temperature results in the deprotonation of the two methylene
groups of the bis-phosphonium salt and formation of a solid of
stoichiometry Cl2Pd{[C(H)PPh3]2CO}, 1, as deduced from its
elemental analysis and mass spectrum (see Experimental Section
and Scheme 1). The IR spectrum clearly shows the cis-
disposition of the chlorine ligands11stwo absorptions at 293
and 278 cm-1sand the location of these bands at low wave-
numbers suggests a Cl-trans-to-C arrangement.12 The ν(CO)
(1) (a) Johnson, A. W.; Kaska, W. C.; Starzewski, K. A. O.; Dixon, D.
A. Ylides and Imines of Phosphorous; John Wiley & Sons: New York,
1993; Chapter 14 and references given therein. (b) Schmidbaur, H.
Acc. Chem. Res. 1975, 8, 62. (c) Schmidbaur, H. Angew. Chem., Int.
Ed. Engl. 1983, 22, 907.
(2) Falvello, L. R.; Ferna´ndez, S.; Navarro, R.; Pascual, I.; Urriolabeitia,
E. P. J. Chem. Soc., Dalton Trans. 1997, 763 and references therein.
(3) Falvello, L. R.; Ferna´ndez, S.; Navarro, R.; Urriolabeitia, E. P. Inorg.
Chem. 1996, 35, 3064 and references therein.
(4) Falvello, L. R.; Ferna´ndez, S.; Navarro, R.; Urriolabeitia, E. P. Inorg.
Chem. 1997, 36, 1136 and references therein.
(5) Falvello, L. R.; Ferna´ndez, S.; Navarro, R.; Urriolabeitia, E. P. New.
J. Chem. 1997, 21, 909.
(8) Vicente, J.; Chicote, M. T.; Sauras-Llamas, I.; Jones, P. G.; Meyer-
Ba¨se, K.; Erdbru¨gger, C. F. Organometallics 1988, 7, 997.
(9) Booth, B. L.; Smith, K. G. J. Organomet. Chem. 1981, 220, 229.
(10) Sanchi, R. R.; Bonsal, K.; Mehrotra, R. C. J. Organomet. Chem. 1986,
303, 351.
(11) Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coor-
dination Compounds, 4th edition; John Wiley & Sons: New York,
1986; Chapter 3, p 326 and references therein.
(6) Ferna´ndez, S.; Garc´ıa, M. G.; Navarro, R.; Urriolabeitia, E. P. J.
Organomet. Chem., in press.
(7) Barco, I. C.; Falvello, L. R.; Ferna´ndez, S.; Navarro, R.; Urriolabeitia,
E. P. J. Chem. Soc., Dalton Trans. 1998, 1699.
(12) Crociani, B.; Boschi, T.; Pietropaolo, R.; Belluco, U. J. Chem. Soc.
(A) 1970, 531.
10.1021/ic980392z CCC: $15.00 © 1998 American Chemical Society
Published on Web 10/28/1998

6008 Inorganic Chemistry, Vol. 37, No. 23, 1998
Falvello et al.
Scheme 1
absorption appears at 1587 cm-1, shifted to lower energies with
compound which, after abstraction of one chlorine, dimerizes
following a well-known pathway for the formation of dinuclear
complexes.16 These facts imply that the bis-ylide group acts
as a chelating ligand in 1.
respect to the free phosphonium (1712 cm-1 13,14
and indicating
)
C-coordination of the ylide.2-7
1
The H NMR spectrum of 1 shows, in additon to complex
Other possible routes to complex 2 were tested, for example
the transmetalation of the bis-ylide from the silver complex [Ag-
{[C(H)PPh3]2CO}]2(ClO4)2 to the palladium derivative PdCl2-
(NCMe)2 or the transylidation reaction (exchange of ylide
ligands) of PdCl2[C(H)COMe(PPh3)]2 with [Ph3PCH2COCH2-
PPh3](ClO4)2. However, the low solubility of the silver deriva-
tive in the first case and the difficulty of completely eliminating
the phosphonium salt [Ph3PCH2COCH3]Cl in the second case
resulted in low yields of pure 2, and these methods are not
described in the Experimental Section. On the other hand, all
attempts to obtain complexes with the bis-ylide coordinated
through only one carbon atom ([M]-C(H)PPh3-COCHdPPh3)
or complexes containing the mono-ylide unit ([M]-C(H)PPh3-
COCH2PPh3) were unsuccessful, even for the more obvious
processes (e.g. reaction of PdCl2(NCMe)2 with the ylide-
phosphonium salt [Ph3PdC(H)COCH2PPh3](ClO4)).
resonances at low field due to Ph groups, a doublet centered at
3.70 ppm, with a coupling constant JP-H of 7 Hz, which is
2
attributed to the ylide proton. The 31P{1H} NMR spectrum of
1 shows a singlet at 25.15 ppm. These spectral parameters
suggest that the bis-ylide is coordinated through both carbon
atoms, although we cannot deduce from these data if the bis-
ylide acts as a chelate (mononuclear) or as a bridging (dinuclear)
ligand. The measurement of the molecular weight in CHCl3
solution was inconclusive, although the value obtained was
closer to that of a mononuclear complex. The reactivity of 1
was more informative.
Thus, 1 equiv of complex 1 reacts with 1 equiv of TlClO4
resulting in the precipitation of TlCl and formation of a yellow
solid of stoichiometry [PdCl{[C(H)PPh3]2CO}](ClO4) 2, ac-
cording to its elemental analysis. The mass spectrum of this
solid shows a weak peak at 1541 amu, which corresponds to
the stoichiometry [PdCl{[C(H)PPh3]2CO}]2(ClO4)+ and strongly
suggests a dinuclear nature for complex 2. The molar conduc-
tivity of 2 in acetone is ΛM ) 177 Ω-1 cm2 mol-1, which agrees
with the average value reported15 for 2:1 electrolytes (180 Ω-1
cm2 mol-1) in the range of concentration employed (6 × 10-4
M). Thus, complex 1 is concluded to be a mononuclear
The IR spectrum of 2 shows the expected changes. The ν-
(Pd-Cl) stretch is shifted to lower energies with respect to 1,
in accord with the change of Cl from terminal to bridging and
ν(CO) shows a value similar to that in 1. The NMR spectral
parameters show the presence of a single product, as can be
1
inferred from the observation of only one doublet in the H
2
NMR spectrum (4.32 ppm, JP-H ) 5.4 Hz) and a singlet in
the 31P{1H} NMR spectrum (23.75 ppm).
(13) Ford, J. A.; Wilson, C. V. J. Org. Chem. 1961, 26, 1433.
(14) Denney, D. B.; Song, J. J. Org. Chem. 1964, 29, 495.
(15) Geary, W. J. Coord. Chem. ReV. 1971, 7, 81.
(16) Urriolabeitia, E. P. J. Chem. Educ. 1997, 74, 325.

Synthesis and Structure of {Pd(µ-Cl){[C(H)PPh3]2CO}}2(ClO4)2‚CH2Cl2
Inorganic Chemistry, Vol. 37, No. 23, 1998 6009
Table 1. Selected Bond Lengths [Å] and Angles [deg] for
2‚CH2Cl2
Pd(1)-C(3)
Pd(1)-Cl(1)
Pd(2)-C(40)
Pd(2)-Cl(1)
P(1)-C(3)
P(1)-C(4)
P(2)-C(1)
P(2)-C(34)
C(1)-C(2)
C(2)-C(3)
P(3)-C(43)
P(3)-C(49)
P(4)-C(73)
P(4)-C(61)
C(41)-O(2)
2.053(11)
2.372(3)
2.061(12)
2.389(3)
Pd(1)-C(1)
Pd(1)-Cl(2)
Pd(2)-C(42)
Pd(2)-Cl(2)
P(1)-C(16)
P(1)-C(10)
P(2)-C(22)
P(2)-C(28)
C(2)-O(1)
P(3)-C(40)
P(3)-C(55)
P(4)-C(42)
P(4)-C(67)
C(40)-C(41)
C(41)-C(42)
2.060(11)
2.389(3)
2.078(11)
2.390(3)
1.774(11)
1.789(12)
1.766(11)
1.789(13)
1.468(16)
1.471(16)
1.800(14)
1.825(15)
1.784(13)
1.803(13)
1.234(15)
1.774(12)
1.810(13)
1.779(12)
1.795(13)
1.243(15)
1.779(12)
1.822(13)
1.772(12)
1.792(13)
1.460(18)
1.471(17)
C(3)-Pd(1)-C(1)
68.8(4)
C(3)-Pd(1)-Cl(1)
C(3)-Pd(1)-Cl(2)
Cl(1)-Pd(1)-Cl(2)
169.2(3)
102.6(3)
87.49(10)
C(1)-Pd(1)-Cl(1) 101.0(3)
C(1)-Pd(1)-Cl(2) 171.3(3)
C(40)-Pd(2)-C(42) 68.0(5)
C(42)-Pd(2)-Cl(1) 169.0(3)
C(42)-Pd(2)-Cl(2) 103.9(3)
C(40)-Pd(2)-Cl(1) 101.1(3)
2+
Figure 1. Thermal ellipsoid plot of the [Pd(µ-Cl){[C(H)PPh3]2CO}]2
cation. Atoms are drawn at the 50% probability level.
C(40)-Pd(2)-Cl(2) 171.4(3)
Cl(1)-Pd(2)-Cl(2)
87.06(11)
Pd(1)-Cl(1)-Pd(2)
C(2)-C(1)-Pd(1)
O(1)-C(2)-C(1)
C(1)-C(2)-C(3)
P(1)-C(3)-Pd(1)
87.82(10) Pd(1)-Cl(2)-Pd(2)
83.4(7)
125.5(11) O(1)-C(2)-C(3)
104.5(11) C(2)-C(3)-Pd(1)
123.8(6)
87.40(10)
125.1(6)
127.4(11)
83.6(7)
P(2)-C(1)-Pd(1)
Due to the presence of two chiral centers in 1, two
diastereoisomers would be expected (RR or SS and RS or SR)
along with two sets of signals in the NMR spectrum. However,
only one set is observed and hence only one diastereoisomer is
obtained (no splitting or broadening of the signals was observed
in the NMR spectrum at low temperaturesCD2Cl2, 183 Ks
ruling out a fast interconversion equilibrium between the two
isomers). The same holds for 2, in which four chiral centers
are present, but only one set of resonances is observed. The
elucidation of the stereochemistry of complexes 1 and 2 comes
from the X-ray structure determination of compound 2‚CH2-
Cl2.
Crystals suitable for X-ray analysis were obtained by slow
diffusion of n-hexane into a CH2Cl2 solution of 2 at room
temperature. A drawing of the organometallic dinuclear cation
is shown in Figure 1, selected bond distances and angles are
collected in Table 1 and relevant crystallographic parameters
are given in Table 2.
The complex crystallizes in the paramorphic orthorhombic
space group P212121, with one molecule in the asymmetric unit.
Thus, just one diastereoisomer is present. Each palladium atom
is located in a distorted square-planar environment, surrounded
by the two bridging chlorine atoms and the two ylide carbon
atoms. This confirms the dinuclear nature of this complex and
the C,C-chelating coordination mode of the bis-ylide ligand.
The atom Pd(2) deviates 0.026 (5) Å from the best least-squares
plane defined by C(40), C(42), Cl(1), and Cl(2), and Pd(1)
deviates -0.046 (5) Å from the plane defined by C(1), C(3),
Cl(1), and Cl(2).
The basic skeleton C(40)-C(42)-Pd(2)-Cl(1)-Cl(2)-Pd-
(1)-C(1)-C(3) is not planar, and the dihedral angle between
the coordination planes is 145.38 (27)°. The coordination planes
are defined as the best least-squares planes formed with C(40)-
C(42)-Cl(1)-Cl(2)-Pd(2) and C(1)-C(3)-Cl(1)-Cl(2)-Pd-
(1). The value of this angle is similar to those reported in some
other dinuclear palladium(II) complexes with halide bridges;
for di-µ-bromobis-π-cycloheptenyldipalladium(II) the value
reported17a is 139°, for di-µ-chlorobis-π-1,3-dimethylallyldi-
palladium(II)17b this value is 150°, and for di-µ-chlorobis{[2,6-
dimethyl-N-(benzylidene)phenylaminato-C2′,N]pallad-
C(41)-C(40)-Pd(2) 83.4(8)
O(2)-C(41)-C(40) 128.0(12)
P(3)-C(40)-Pd(2) 126.5(7)
O(2)-C(41)-C(42) 126.2(12) C(40)-C(41)-C(42) 104.2(11)
C(41)-C(42)-Pd(2) 82.5(7)
P(4)-C(42)-Pd(2) 128.5(6)
a
Table 2. Crystallographic Data for 2‚CH2Cl2
empirical formula
fw
C79H66Cl6O10P4Pd2
1724.70
T
λ
-123(1) °C
0.71073 Å
P212121 (No. 19)
19.247(5) Å
19.521(4) Å
19.757(4) Å
7423(3) Å3
4
space group
a
b
c
V
Z
Fcalcd
1.543 g cm-3
8.46 cm-1
0.0578
µ
R1 [I > 2σ(I)]a
wR2 [I > 2σ(I)]b
0.1216
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) [∑w(Fo2 - Fc2)2/∑w(Fo )2]1/2
.
2
ium(II)}18 the reported value is 143.3(1)°. However, this feature
is rather unusual in palladium(II) complexes, where the normal
arrangement of the ligands results in planar dinuclear complexes,
that is, the two coordination planes are coplanar. One of the
facts which gives significant deviations from the planarity is
the presence of metal-metal interactions, but there is no reason
to suppose that these molecules are affected by metal-metal
bonding. The Pd-C (ylide) bond distances [range 2.053(11)-
2.078(11) Å] are similar, within experimental error, to those
found in other C-coordinated ylide Pd complexes2,19 and the
palladium-chlorine bond distances [range 2.372(3)-2.390(3)
Å] are also similar to those found in related dinuclear di-µ-
chlorine Pd complexes.18,20
The environment of each ylide carbon [C(1), C(3), C(40),
and C(42)] is tetrahedral, with the PPh3 substituents on the same
(18) Crispini, A.; De Munno, G.; Ghedini, M.; Neve, F. J. Organomet.
Chem. 1992, 427, 409.
(19) Vicente, J.; Chicote, M. T.; Sauras-Llamas, I.; Lo´pez-Mun˜oz, M. J.;
Jones, P. G. J. Chem. Soc., Dalton Trans. 1990, 3683.
(20) Parra-Hake, M.; Rettig, M. F.; Wing, R. M.; Woolcock, J. C.
Organometallics 1982, 1, 1478.
(17) (a) Kilbourn, B. T.; Mais, R. H. B.; Owston, P. G. J. Chem. Soc.,
Chem. Commun. 1968, 1438. (b) Davies, G. R.; Mais, R. H. B.;
O’Brien, S.; Owston, P. G. J. Chem. Soc., Chem. Commun. 1967, 1151.

6010 Inorganic Chemistry, Vol. 37, No. 23, 1998
Falvello et al.
side of the coordination plane within each fragment [PdCl(bis-
ylide)] and on opposite sides at the two ends of the molecule.
That gives absolute configurations for the ylide carbon atoms
SC(1), RC(3), SC(40), and RC(42). Thus, the molecule crystallizes
in one of the meso forms. Due to the fact that only one
stereoisomer is observed in solution for 2 (within the range of
detection of the NMR spectrometer), we can conclude that the
RS configuration for the ylide carbon atoms of the chelating
bis-ylide ligand is preseved in solution, and that for complex 1
these, and not the RR/SS configurations, are the absolute
configurations for the carbon atoms. These facts are depicted
in Scheme 1. A similar disposition of the substituents around
the ylide carbon atoms has been found in the gold(I) derivative8
[Au2{µ-{{CH(PPh3)}2CO}}2](ClO4)2.
Finally, there is a short metal-hydrogen contact C(56)-
H(56)‚‚‚Pd(2) [M-H ) 2.71(2) Å], similar to that found in [Pd-
(H1-nabz)2]21 [2.66(7) Å]. We have not been able to isolate
the solution 1H NMR signal of this proton among the aromatic
protons,22 and thus we cannot positively characterize this as an
intramolecular three-center four-electron or three-center two-
electron interaction.21
conclusions can be inferred from the analysis of the spectra of
complex 5.
The cleavage of the halide bridge system in 2 can also be
carried out with other ligands. We have tried reactions with
R-stabilized phosphoylide ligands Ph3PdC(H)COR (R ) Me,
Ph, OMe) and Ph3PdC(H)CN. Surprisingly, the keto-stabilized
ylides do not produce the cleavage of the chloride bridge, and
the starting products can be recovered unaltered. The reaction
with the cyano-stabilized ylide Ph3PdC(H)CN (1:2 molar ratio)
gives a product of stoichiometry [PdCl{[C(H)PPh3]2CO}(Ph3-
PCHCN)](ClO4), 6, according to its elemental analysis and mass
spectrum (see Experimental Section). The cleavage of the
bridging system can be inferred from the observation in the 1H
NMR spectrum of 6 of two doublets attributed to the ylide
2
2
protons (3.96 ppm, JP-H ) 6 Hz; 3.86 ppm, JP-H ) 4 Hz)
and the coordination mode of the ylide from the appearance of
a doublet in the high field region (1.02 ppm, 2JP-H ) 6.3 Hz),
which is indicative of N-coordination of the ylide.4 The 31P-
{1H} NMR spectrum shows the expected resonances; an AB
spin system for the ylide phosphorus (25.90 and 24.20 ppm,
4JP-P ) 11 Hz) and a singlet for the N-bonded ylide (22.84
ppm). It is worth noting the selective N-coordination of the
ylide in 6. In similar reactions performed with the halide
bridged [Pd(dmba)(µ-Cl)]2 (dmba ) C6H4CH2NMe2-2), the
reaction product contained a mixture of the C- and N-bonded
forms, probably in thermal equilibrium, and both of them were
postulated to be trans to the N atom of the cyclometalated
ligand.4 Here, complex 6 shows a single coordination form,
and this fact could be rationalized by two factors. The first is
the antisymbiotic behavior of the Pd(II) center,23 which results
in a higher stability of the N-bonded ylide (“borderline” base24)
trans to the ylide carbon atom (soft base) than of a C-trans-
to-C arrangement. The second factor is the low steric require-
ment of the N-bonded ylide, compared to the C-form, in a cis
position to the bulky C(H)PPh3 fragment.
The reactivity of complex 2 is as expected for a dinuclear
system with chlorine bridges. Thus, treatment of 2 with TlClO4
(1:2 molar ratio) in NCMe results in the formation of the bis-
solvate [Pd{[C(H)PPh3]2CO}(NCMe)2](ClO4)2, 3. In these
syntheses we have avoided the use of AgClO4 as halide
abstracting agent because of the formation of the very insoluble
salt [Ag2{µ-{{CH(PPh3)}2CO}}2](ClO4)28 as a consequence of
a lateral transmetalation process. For the same reason, the
synthesis of 2 starting from 1 was carried out with the thallium
salt instead of the silver. The IR spectrum of 3 shows the
expected absorptions corresponding to the presence of coordi-
nated NCMe, and the 1H NMR and 31P{1H} NMR spectra show
a doublet at 4.51 ppm (2JP-H ) 3.1 Hz), and a singlet at 25.00
ppm, respectively, corresponding to the ylide proton and to the
phosphorus. The stereochemistry for the chelate bis-ylide
moiety in 3 is likely to be similar to that described for 2 (see
Scheme 1), assuming that the Pd-C bonds remain unbroken in
the reaction.
Complex 2 also undergoes other reactions typical of halide
bridges, such as substitution by anionic chelating ligands. Thus,
2 reacts with Tl(acac) (1:2 molar ratio) to give the acetylac-
etonato derivative [Pd(acac-O,O′){[C(H)PPh3]2CO}](ClO4) 7.
The characterization of 7 results from the same considerations
as those used previously; the key indicators are the ν(CO) in
the IR spectrum and the chemical shifts of the ylide proton and
the phosphorus in the NMR spectra (see Experimental Section).
The reactivity of the bis-solvate 3 has also been explored.
Thus, complex 3 reacts with the ylide Ph3PdC(H)CN (1:2) to
give [Pd{[C(H)PPh3]2CO}(NC-C(H)dPPh3)2](ClO4)2, 8 (see
Scheme 1), in which both NCMe ligands have been replaced
by the ylide Ph3PdC(H)CN as characterized by the elemental
analysis and mass spectrum. The IR spectrum of 8 shows the
expected absorptions corresponding to the bis-ylide (ν(CO) )
1615 cm-1) and to the cyano-ylide (ν(CN) ) 2175 cm-1). The
most interesting feature of this complex is the presence of two
cyano-ylides N-bonded to the Pd(II) center, as can be inferred
Treatment of 2 with bases such as pyridine or 3,5-lutidine
(1:2.5 molar ratio) in CH2Cl2 promotes the symmetrical cleavage
of the bridging system and formation of the corresponding
complexes of stoichiometry [PdCl{[C(H)PPh3]2CO}(L)](ClO4)
(L ) pyridine (4), 3,5-lutidine (5)). The IR spectra of 4 and 5
show a slight increase in energy of the Pd-Cl stretch,
corresponding to the change from bridging to terminal coordina-
tion, in addition to the absorptions attributed to the bis-ylide
and to the pyridine ligands. The 1H NMR spectrum of 4 shows
the presence of two doublet resonances attributed to the two
nonequivalent ylide proton atoms, one at 4.80 ppm (2JP-H ) 6
Hz) and the other at 4.51 ppm (2JP-H ) 4.5 Hz), together with
characteristic resonances of coordinated pyridine (see Experi-
mental Section). The 31P{1H} NMR spectrum shows the
presence of an AB spin sytem (25.75 and 24.55 ppm) with a
coupling constant of 4JP-P ) 12 Hz. These observations are in
accord with the structure depicted in Scheme 1. Similar
1
from the H NMR. The resonance attributed to the bis-ylide
appears at 4.48 ppm (2JP-H ) 3.6 Hz) while the resonance
attributed to the cyano-ylide appears at 0.86 ppm (2JP-H ) 5.4
Hz), typical for N-coordination of this ylide.4 The relative
intensity of these resonances is 1:1, confirming the complete
substitution of the NCMe ligand. Further evidence for the
proposed structure (see Scheme 1) can be obtained from the
31P{1H} NMR spectrum, which shows two resonances of relative
intensity 1:1 (24.65 ppm for the bis-ylide and 22.92 ppm for
(21) Kawamoto, T.; Nagasawa, I.; Kuma, H.; Kushi, Y. Inorg. Chem. 1996,
35, 2427 and references therein.
(22) However, the positioning of this proton atom leaves it ideally located
to undergo an orthometalation process, and, in fact, compound 2 can
be transformed into its orthometalated isomer [Pd(µ-Cl)(C6H4-
PPh2C(H)COCH2PPh3)]2(ClO4)2 in an intramolecular acid-base reac-
tion: Falvello, L. R.; Ferna´ndez, S.; Navarro, R.; Rueda, A.;
Urriolabeitia, E. P. Organometallics, in press.
(23) Pearson, R. G. Inorg. Chem. 1973, 12, 712.
(24) Davies, J. A.; Hartley, F. R. Chem. ReV. 1981, 81, 79.

Synthesis and Structure of {Pd(µ-Cl){[C(H)PPh3]2CO}}2(ClO4)2‚CH2Cl2
Inorganic Chemistry, Vol. 37, No. 23, 1998 6011
the N-coordinated ylide).4 This behavior is rather different from
that observed for this ylide in C,N-cyclometalated complexes.4
There, the reaction of the cationic complex [Pd(dmba)-
(NCMe)2]+ with 2 equiv of Ph3PdC(H)CN gave [Pd(dmba)-
{C(H)PPh3(CN)}{NC-C(H)dPPh3}]+ in which the C-bonded
ylide was trans to the N atom of the dmba and the N-bonded
ylide was trans to the orthometalated atom of the dmba group.4
Taking into account the preceding discussion for complex 6,
the structure of complex 8 can be easily explained in terms of
the antisymbiotic effect (the hardest atom of the cyano-ylide,
that is, the N atom, would be more stabilized trans to the carbon
atom of the bis-ylide) and of the steric interactions (due to the
large volume of the bis-ylide, the low steric requirements of
the N-bonded ylide are preferred).
ylide ligand and the other one at 1557 cm-1 and attributed to
the asymmetric stretch of the acetate ligand30 (the symmetric
stretch falls in the polyethylene region, precluding its observa-
tion). The NMR spectra show high symmetry in the molecule.
Thus, in the 1H NMR the resonance attributed to the ylide proton
appears as a doublet at 4.92 ppm (2JP-H ) 5.6 Hz) and the
methyl group of the acetate ligand as a singlet at 1.41 ppm.
The 31P{1H} NMR shows a single resonance at 26.41 ppm.
Several dinuclear structures are consistent with these data: (i)
the bis-ylide and the acetate bridge two palladium atoms, (ii)
the bis-ylide acts as a chelate and the acetate as bridge, and
(iii) the bis-ylide acts as a bridge and the acetate as a chelate.
We propose the second possibility as the most plausible, since
in complexes 1-9 the bis-ylide acts as a chelate and shows
good stability. Moreover, the spectral parameters (IR, NMR)
of the coordinated chelating bis-ylide in 1-9 and those of 10
are very similar. Moreover, the acetate group is a very good
bridging ligand, giving “open-book” structures.31 The high
symmetry of the molecule shown in the NMR spectra allows
us to propose the structure shown in Scheme 1. We think that
this disposition of the ligands, with the ylide H atoms on the
inner side of the “book”, is less sterically hindered and accounts
for the symmetry.
It is interesting to note that all similar complexes described
to date possess, trans to the bis-ylide, ligands with donor atoms
which behave as borderline or hard bases (Cl-, NCMe, pyridine,
N-bonded ylides, acac-).24 We have decided to explore other
interesting “hard” O-donor ligands, such as the hydroxy group
OH-, which is scarcely represented in palladium(II) chem-
istry,25-27 and which shows a very interesting reactivity.28,29 The
reaction of 3 with a methanolic solution of NBu4OH (1:2.1
molar ratio) results in the immediate precipitation of the
dinuclear complex [Pd(µ-OH){[C(H)PPh3]2CO}]2(ClO4)2, 9, as
deduced from its elemental analysis and mass spectrum. The
presence of the OH ligand is inferred from the observation in
Conclusion
A series of new complexes with the bis-ylide {[Ph3PdC(H)]2-
CO} has been prepared and one of the new products has been
structurally characterized by X-ray diffraction. In all of the
complexes the bis-ylide acts as a C,C-chelate. The presence
of two soft carbon atoms on the palladium center appears to
stabilize the coordination of hard ligands, such as the OH group,
and is able to drive the selective coordination of ambidentate
ligands through their hardest atoms. The results derived so far
from this chemistry suggest that further novel, interesting
systems may await study.
1
the IR spectrum of 9 of an absorption at 3602 cm-1. The H
NMR spectrum shows the resonances attributed to the ylide
proton at 3.78 ppm (2JP-H ) 6.6 Hz), and the resonance due to
the OH group at -4.44 ppm as a singlet. The relative intensities
of these resonances (2:1) confirm the bridging nature of the
OH group. The 31P{1H} NMR spectrum shows a single
resonance at 23.99 ppm. Further treatment of 9 with NBu4OH
does not promote the formation of the bis-hydroxo derivative
[Pd(OH)2{[C(H)PPh3]2CO}], and the reaction of 3 with an
excess of NBu4OH (1:6 molar ratio) gives 9 as the only reaction
product. It seems that the bridging arrangement confers a
special stability to this ligand. However, 9 reacts with the
phosphonium salt [Ph3PCH2CN]Cl to give a (1:1) mixture of 2
and 6. The reactivity of 9 in other processes is presently under
study.
Experimental Section
Safety Note. Caution! Perchlorate salts of metal complexes with
organic ligands are potentially explosiVe. Only small amounts of these
materials should be prepared, and they should be handled with great
caution.
General Procedures. Solvents were dried and distilled under
nitrogen before use: diethyl ether and tetrahydrofuran over benzophe-
none ketyl, dichloromethane, and chloroform over P2O5, acetonitrile
over CaH2, methanol over magnesium and n-hexane over sodium.
Elemental analyses were carried out on a Perkin-Elmer 240-B mi-
croanalyzer. Infrared spectra (4000-200 cm-1) were recorded on a
Perkin-Elmer 883 Infrared spectrophotometer from Nujol mulls between
polyethylene sheets. 1H (300.13 MHz) and 31P{1H} (121.49 MHz)
NMR spectra were recorded in CDCl3 or CD2Cl2 solutions at room
temperature (unless otherwise stated) on a Bruker ARX-300 spectrom-
Finally, the reaction of Pd(OAc)2 with the mixed ylide-
phosphonium salt [Ph3PdC(H)COCH2PPh3](ClO4) (1:1 molar
ratio) results in the formation of the acetate bridged dimer [Pd-
(µ-OOCCH3){[C(H)PPh3]2CO}]2(ClO4)2, 10. The elemental
analyses and mass spectrum are in good agreement with the
proposed stoichiometry, and the conductivity data in acetone
solution (ΛM ) 217 Ω-1 cm2 mol-1) confirms the dicationic
character of 10. Complex 10 can also be obtained by reaction
of 2 with TlOOCCH3 (1:2 molar ratio), although in this case
the yield is notably lower. We are unaware of the reasons of
this low yield, and for this reason this synthetic method has
not been included in the Experimental Section.
1
eter; H was referenced using the solvent signal as internal standard
and 31P{1H} was externally referenced to H3PO4 (85%). Mass spectra
(positive ion FAB) were recorded on a V. G. Autospec. Molecular
weight determinations were made on a Knauer vapor pressure osmom-
eter. Electrical conductivity measurements were performed in acetone
solutions with concentrations around 5 × 10-4 M with a Philips PW
9509 conductivity cell. The starting compounds Pd(OAc)2,32 Ph3Pd
C(H)CN,33 [Ph3PCH2COCH2PPh3]Cl2,13,14 and [Ph3PdC(H)COCH2-
The IR spectrum of 10 shows two strong absorptions in the
carbonyl region; one at 1611 cm-1 and attributed to the bis-
(25) Bryndza, H. E.; Tam, W. Chem. ReV. 1988, 88, 1163.
(26) (a) Lo´pez, G.; Garc´ıa, G.; Ruiz, J.; Sa´nchez, G.; Garc´ıa, J.; Vicente,
C. J. Chem. Soc., Chem. Commun. 1989, 1045. (b) Lo´pez, G.; Ruiz,
J.; Garc´ıa, G.; Vicente, C.; Casabo´, J.; Molins, E.; Miratvilles, C. Inorg.
Chem. 1991, 30, 2605.
(27) Wimmer, S.; Castan, P.; Wimmer, F. L.; Johnson, N. P. J. Chem.
Soc., Dalton Trans. 1989, 403.
(28) Ganguly, S.; Mague, J. T.; Roundhill, D. M. Inorg. Chem. 1992, 31,
3831.
(29) Ruiz, J.; Mart´ınez, M. T.; Vicente, C.; Garc´ıa, G.; Lo´pez, G.; Chaloner,
P. A.; Hitchcock, P. B. Organometallics 1993, 12, 4321.
8
PPh3]ClO4 were prepared according to published methods.
(30) Deacon, G. B.; Phillips, R. J. Coord. Chem. ReV. 1980, 33, 227.
(31) Navarro-Ranninger, C.; Lo´pez-Solera, I.; Alvarez-Valde´s, A.; Rod-
r´ıguez-Ramos, J. H.; Masaguer, J. R.; Garc´ıa-Ruano, J. L.; Solans, X.
Organometallics 1993, 12, 4104.
(32) Stephenson, T. A.; Morehouse, S. M.; Powell, A. R.; Heffer, J. P.;
Wilkinson, G. J. Chem. Soc. 1965, 3632.
(33) Trippett, S.; Walker, D. M. J. Chem. Soc. 1959, 3874.

6012 Inorganic Chemistry, Vol. 37, No. 23, 1998
Falvello et al.
Preparations. Cl2Pd[{C(H)PPh3}2CO], 1. To a solution of Pd-
(OAc)2 (0.200 g, 0.890 mmol) in CH2Cl2 (20 mL) at room temperature,
[Ph3PCH2COCH2PPh3]Cl2 (0.580 g, 0.890 mmol) was added. The
resulting orange solution was stirred for 5 h at room temperature, then
evaporated to dryness. By addition of Et2O (40 mL) to the oily residue
and continuous stirring 1 was obtained as an orange solid, which was
filtered, washed with additional Et2O (20 mL) and air-dried. The crude
solid was recrystallized from CH2Cl2/n-hexane, giving orange crystals
of 1‚0.5CH2Cl2. Obtained: 0.553 g (82% yield). The crystals of
1‚0.5CH2Cl2 were used for elemental analyses and NMR measurements.
The amount of CH2Cl2 was determined by 1H NMR integration. Anal.
Found for C39H32Cl2OP2Pd‚0.5CH2Cl2: C, 58.51; H, 4.24. Calcd: C,
59.42; H, 4.16. MS (+ FAB) [m/z (%)]: 721 [(M - Cl)+, 6%]. IR
(cm-1): 1587 (νCO), 293, 278 (νPd-Cl). 1H NMR (CDCl3): δ 8.08-
{PdCl[NC-C(H)dPPh3][{C(H)PPh3}2CO]}(ClO4), 6. To a solu-
tion of 2 (0.163 g, 0.100 mmol) in CH2Cl2 (25 mL) at room temperature,
Ph3PdC(H)CN (0.090 g, 0.30 mmol) was added. The resulting solution
was stirred for 1 h, then evaporated to dryness. The oily residue was
treated with Et2O (30 mL) giving 6 as a pale yellow solid, which was
filtered, washed with additional Et2O (30 mL) and air-dried. The crude
product was recrystallized from CH2Cl2/n-hexane, giving pale yellow
crystals of 6‚0.5CH2Cl2. Obtained: 0.191 g (85% yield). These crystals
were used for analytical and spectroscopic purposes. The amount of
CH2Cl2 was established by 1H NMR integration. Anal. Found for
C59H48Cl2NO5P3Pd‚0.5CH2Cl2: C, 61.82; H, 4.18; N, 0.94. Calcd: C,
61.41; H, 4.24; N, 1.20. MS (+ FAB) [m/z (%)]: 1020 [M+, 10%].
IR (cm-1): 2166 (νCN), 1621 (νCO), 299 (νPd-Cl). 1H NMR (CDCl3):
δ 7.88-7.32 (m, 45H, Ph), 3.96 (d, CH ylide, 1H, 2JP-H ) 6 Hz), 3.86
2
2
6.96 (m, 15H, Ph), 3.70 (d, CH ylide, 1H, JP-H ) 7 Hz). 31P{1H}
(d, CH ylide, 1H, JP-H ) 4 Hz), 1.02 (d, CH ylide N-coordinated,
2
1H, JP-H ) 6.3 Hz). 31P{1H} NMR (CDCl3): δ 25.90, 24.20 (AB
NMR (CDCl3): δ 25.15.
4
spin system, 2P, bis-ylide C-coordinated, JP-P ) 11 Hz), 22.84 (s,
{Pd(µ-Cl)[{C(H)PPh3}2CO]}2(ClO4)2, 2. To a solution of 1 (0.200
g, 0.264 mmol) in CH2Cl2 (30 mL) at room temperature, TlClO4 (0.080
g, 0.26 mmol) was added and the resulting suspension was stirred
overnight at room temperature, then filtered. The clear yellow solution
was evaporated to dryness and the residue treated with Et2O (30 mL)
giving 2 as a yellow solid, which was filtered, washed with additional
Et2O (30 mL) and air-dried. The crude solid was recrystallized from
CH2Cl2/n-hexane, giving orange crystals of 2‚CH2Cl2. Obtained: 0.177
g (83% yield). The crystals of 2‚CH2Cl2 were used for elemental
analysis, NMR and X-ray measurements. The amount of CH2Cl2 was
determined by 1H NMR integration. Anal. Found for C78H64Cl4O10P4-
Pd2‚CH2Cl2: C, 54.27; H, 3.74. Calcd: C, 55.01; H, 4.05. MS (+
FAB) [m/z (%)]: 1541 [(M2 - ClO4)+, 20%]. ΛM ) 177 Ω-1 cm2
mol-1 (6 × 10-4 M in acetone). IR (cm-1): 1617 (νCO), 278 (νPd-Cl).
1H NMR (CDCl3): δ 8.07-6.95 (m, 15H, Ph), 4.32 (d, CH ylide, 1H,
2JP-H ) 5.4 Hz). 31P{1H} NMR (CDCl3): δ 23.75.
1P, ylide N-coordinated).
{Pd(acac-O,O′)[{C(H)PPh3}2CO]}(ClO4), 7. To a solution of 2
(0.200 g, 0.122 mmol) in CH2Cl2 (25 mL) at room temperature, Tl-
(acac) (0.107 g, 0.354 mmol) was added and the resulting suspension
was stirred for 2 h at room temperature and then filtered. The clear
pale yellow solution was evaporated to dryness and the residue treated
with Et2O (30 mL) giving 7 as a yellow solid, which was filtered,
washed with additional Et2O (30 mL), filtered and air-dried. Ob-
tained: 0.146 g (67% yield). Anal. Found for C44H39ClO7P2Pd: C,
59.12; H, 4.53. Calcd: C, 59.81; H, 4.44. MS (+ FAB) [m/z (%)]:
783 [M+, 100%]. IR (cm-1): 1610 (νCO-ylide), 1568, 1517 (νCO-acac).
1H NMR (CDCl3): δ 7.63-7.34 (m, 30H, Ph), 4.97 (s, 1H, CH-acac),
2
4.05 (d, CH ylide, 2H, JP-H ) 5.7 Hz), 1.29 (s, 6H, CH3-acac). 31P-
{1H} NMR (CDCl3): δ 25.26.
{Pd[{C(H)PPh3}2CO][NC-C(H)dPPh3]2}(ClO4)2, 8. To a solu-
tion of 3 (0.115 g, 0.119 mmol) in CH2Cl2 (25 mL) at room temperature,
Ph3PdC(H)CN (0.072 g, 0.24 mmol) was added. The resulting solution
was stirred for 2 h at room temperature, then evaporated to dryness.
The residue was treated with Et2O (30 mL) giving 8 as a pale yellow
solid, which was filtered, washed with additional Et2O (30 mL), filtered,
and air-dried. The crude product was recrystallized from CH2Cl2/n-
hexane, giving pale yellow crystals of 8‚CH2Cl2. Obtained: 0.100 g
(56% yield). These crystals were used for analytical and spectroscopic
purposes. The amount of CH2Cl2 was assayed by 1H NMR integration.
Anal. Found for C79H64Cl2N2O9P4Pd‚CH2Cl2: C, 61.48; H, 4.21; N,
1.54. Calcd: C, 61.14; H, 4.23; N, 1.78. MS (+ FAB) [m/z (%)]:
984 [(M - 2ClO4 - NCCHPPh3 + H)+, 20%]. IR (cm-1): 2175 (νCN),
1615 (νCO-ylide). 1H NMR (CDCl3): δ 7.58-7.12 (m, 15H, Ph), 4.48
{Pd[{C(H)PPh3}2CO](NCMe)2}(ClO4)2, 3. To a solution of 2
(1.000 g, 0.610 mmol) in NCMe (60 mL) at room temperature, TlClO4
(0.371 g, 1.220 mmol) was added and the resulting suspension was
stirred overnight at room temperature, then filtered. The clear yellow
solution was evaporated to dryness and the residue treated with Et2O
(30 mL) giving 3 as a yellow solid, which was filtered, washed with
additional Et2O (30 mL) and air-dried. Obtained: 0.955 g (82% yield).
Anal. Found for C43H38Cl2N2O9P2Pd: C, 53.55; H, 3.58; N, 2.89.
Calcd: C, 53.46; H, 3.96; N, 2.51. MS (+ FAB) [m/z (%)]: 785 [(M
- 2NCMe - ClO4)+, 100%]. IR (cm-1): 2327, 2315, 2300, 2288
(νCN), 1634 (νCO). 1H NMR (CD2Cl2, 218 K): δ 7.93-7.41 (m, 15H,
2
Ph), 4.51 (d, CH ylide, 1H, JP-H ) 3.1 Hz), 1.72 (s, 3H, NCMe).
31P{1H} NMR (CD2Cl2, 218 K): δ 25.00.
2
(d, CH ylide C-coordinated, 1H, JP-H ) 3.6 Hz), 0.86 (d, CH ylide
N-coordinated, 1H, 2JP-H ) 5.4 Hz). 31P{1H} NMR (CDCl3): δ 24.65
(bis-ylide C-coordinated), 22.92 (ylide N-coordinated).
{PdCl(py)[{C(H)PPh3}2CO]}(ClO4), 4. To a solution of 2 (0.200
g, 0.122 mmol) in CH2Cl2 (30 mL) at room temperature, pyridine (50
µL, 0.624 mmol) was added. The resulting solution was stirred for 3
h, then evaporated to dryness. The oily residue was treated with Et2O
(30 mL) giving 4 as a yellow solid, which was filtered, washed with
additional Et2O (30 mL) and air-dried. Obtained: 0.185 g (84% yield).
Anal. Found for C44H37Cl2NO5P2Pd. C, 58.47; H, 3.80; N, 1.72.
Calcd: C, 58.78; H, 4.15; N, 1.56. MS (+ FAB) [m/z (%)]: 798 [M+,
12%], 719 [(M - py)+, 50%]. IR (cm-1): 1601 (br, νCO), 302 (νPd-Cl).
1H NMR (CDCl3): δ 8.75 (m, 2H, H2 and H6, py), 8.20 (m, 1H, H4,
py), 7.97-6.98 (m, 30H, Ph), 6.74 (m, 2H, H3 and H5, py), 4.80 (d,
CH ylide, 1H, 2JP-H ) 6 Hz), 4.51 (d, CH ylide, 1H, 2JP-H ) 4.5 Hz).
{Pd(µ-OH)[{C(H)PPh3}2CO]}2(ClO4)2, 9. To a solution of 3
(0.173 g, 0.179 mmol) in MeOH (30 mL) at room temperature, NBu4-
OH (0.097 g, 0.38 mmol) was added. A yellow solid precipitated
almost instantaneously. This suspension was stirred for 30 min at room
temperature and then filtered. The yellow solid of 9 was washed with
MeOH (5 mL) and Et2O (30 mL) and then air-dried. The product was
recrystallized as usual from CH2Cl2/n-hexane giving yellow crystals
of 9‚1.5CH2Cl2. Obtained: 0.100 g (69% yield). Anal. Found for
C78H66Cl2O12P4Pd2‚1.5CH2Cl2: C, 55.03; H, 3.90. Calcd: C, 55.18;
H, 4.02. MS (+ FAB) [m/z (%)]: 1503 [(M2 - ClO4)+, 5%]. IR
(cm-1): 3602 (νOH), 1594 (νCO-ylide). 1H NMR (CDCl3): δ 8.21-6.90
(m, 30H, Ph), 3.78 (d, CH ylide, 2H, 2JP-H ) 6.6 Hz), - 4.44 (s, 1H,
µ-OH). 31P{1H} NMR (CDCl3): δ 23.99.
{Pd(µ-OOCCH3)[{C(H)PPh3}2CO]}2(ClO4)2, 10. To a solution
of Pd(OAc)2 (0.139 g, 0.619 mmol) in CH2Cl2 (25 mL), [Ph3PdC(H)-
COCH2PPh3]ClO4 (0.421 g, 0.619 mmol) was added. The resulting
orange solution was stirred for 5 h at room temperature and then
evaporated to dryness. The residue was treated with CHCl3 (20 mL)
giving 10 as an orange solid, which was collected and air-dried.
Obtained: 0.187 g (36% yield). The solution was evaporated to dryness
and the residue was treated with Et2O (20 mL). An orange solid was
obtained, which was identified as 10 contaminated with very small
amounts of an unidentified compound. A second recrystallization
4
31P{1H} NMR (CDCl3): δ 25.75, 24.55 (AB spin system, JP-P ) 12
Hz).
{PdCl(3,5-lu)[{C(H)PPh3}2CO]}(ClO4), 5. Complex 5 was syn-
thesized similarly to 4. Complex 2 (0.300 g, 0.182 mmol) was reacted
with 3,5-lutidine (41.7 µL, 0.365 mmol) in CH2Cl2 (30 mL) to give 5
as a yellow solid. Obtained: 0.295 g (87% yield). Anal. Found for
C46H41Cl2NO5P2Pd: C, 59.10; H, 4.01; N, 1.68. Calcd: C, 59.59; H,
4.46; N, 1.51. MS (+ FAB) [m/z (%)]: 826 [M+, 20%], 719 [(M -
lu)+, 65%]. IR (cm-1): 1601 (br, νCO), 284 (νPd-Cl). 1H NMR
(CDCl3): δ 8.51 (m, 2H, H2 and H6, lu), 8.12-6.98 (m, 31H, Ph+H4),
4.67 (d, CH ylide, 1H, 2JP-H ) 6 Hz), 4.43 (d, CH ylide, 1H, 2JP-H
)
4.2 Hz), 1.91 (s, 6H, CH3, lu). 31P{1H} NMR (CDCl3): δ 25.75, 24.40
4
(AB spin system, JP-P ) 12 Hz).

Synthesis and Structure of {Pd(µ-Cl){[C(H)PPh3]2CO}}2(ClO4)2‚CH2Cl2
Inorganic Chemistry, Vol. 37, No. 23, 1998 6013
carried out in CHCl3 (5 mL) gave a second fraction of pure 10.
Obtained: 0.197 g (38% yield; net yield of 10: 74%). Anal. Found
for C82H70Cl2O14P4Pd2: C, 58.78; H, 3.80. Calcd: C, 58.38; H, 4.18.
MS (+ FAB) [m/z (%)]: 1587 [(M2 - ClO4)+, 10%]. ΛM ) 217 Ω-1
cm2 mol-1 (acetone solution, 5 × 10-4 M). IR (cm-1): 1611 (νCO-ylide),
1557 (νCO2-asym). 1H NMR (CD2Cl2): δ 7.78-7.71 (m, 9H, Ph), 7.52-
7.46 (m, 6H, Ph), 4.92 (d, CH ylide, 1H, 2JP-H ) 5.6 Hz), 1.41 (s, 3H,
CH3-acetate). 31P{1H} NMR (CD2Cl2): δ 26.41.
Crystal Structure Determination of 2‚CH2Cl2. A yellow crystal
of 2‚CH2Cl2 was mounted on a quartz fiber and covered with epoxy.
Normal procedures were used for the determination of the unit cell
constants and for the measurement of intensity data. After preliminary
indexing and transformation of the cell to a conventional setting, axial
photographs were taken of the a, b, and c axes to verify the lattice
dimensions and symmetry. Unit cell dimensions were determined from
25 centered reflections in the range 22.0 e 2θ e 30.1°. For intensity
data collection, pure ω-scans were used with ∆ω ) 1.00 + 0.35 tan θ.
Three monitor reflections measured after every 3 h of beam time showed
a decay of 16% over the period of data collection. The orientation of
the crystal was checked after every 700 intensity measurements.
Absorption corrections34 were based on azimuthal scans of 10 reflections
which had the Eulerian angle ø near 90°.
atomic sites in an interstitial zone were modeled as a disordered CH2-
Cl2 molecule. One of the chlorine atoms [Cl(5)] of this group is
disordered over three positions with partial occupancies of 0.600, 0.200,
and 0.200. The hydrogens atoms of this molecule were omitted from
the model. At the end of the refinement, there was only one difference
Fourier peak with F > 1.00 e/Å3, in the area of the disordered CH2Cl2
molecule. The data-to-parameter ratio in the final refinement was 7.7.
2
The structure was refined to Fo , and all reflections were used in the
least-squares calculation.36a To determine the correct absolute structure
the Flack x parameter was refined.36b,c Once the enantiomorph had
been established, the Flack parameter was not refined again, but rather
estimated following the least-squares calculations. The residuals and
other pertinent parameters are summarized in Table 2. Crystallographic
calculations were done on a Local Area VAXCluster (VAX/VMS
V5.5-2). Data reduction was done by the program XCAD4B.37
Acknowledgment. We thank the Direccio´n General de
Ensen˜anza Superior (Spain) for financial support (Projects PB95-
0003-C02 and PB95-0792) and Prof. J. Fornie´s for invaluable
logistical support.
Supporting Information Available: An X-ray crystallographic file,
in CIF format, for the structure determination of 2‚CH2Cl2 is available
on the Internet only. Access information is given on any current
masthead page.
The structure was solved and developed by Patterson and Fourier
methods.35 All non-hydrogen atoms were assigned anisotropic dis-
placement parameters. All hydrogen atoms of compound 2 (including
those of the ylide groups, which were observed in a difference map)
were placed at idealized positions and treated as riding atoms with
isotropic displacement parameters set to 1.2 times the equivalent
isotropic displacement parameters of their respective parent atoms. Five
IC980392Z
(36) (a) Sheldrick, G. M. SHELXL-97: FORTRAN program for the
refinement of crystal structures from diffraction data; Go¨ttingen
University: Germany, 1997. (b) Flack, H. D. Acta Crystallogr. 1983,
A39, 876. (c) Bernardinelli, G.; Flack, H. D. Acta Crystallogr. 1985,
A41, 500.
(34) Absorption corrections and molecular graphics were done using the
commercial package SHELXTL-PLUS, Release 4-21/V; Siemens
Analytical X-ray Instruments, Inc.: Madison, WI, 1990.
(35) Sheldrick, G. M. SHELXS-86. Acta Crystallogr. 1990, A46, 467.
(37) Harms, K., private communication, 1995.