Polynuclear homo- or heterometallic palladium(II)-platinum(II) pentafluorophenyl complexes containing bridging diphenylphosphido ligands. 6. Syntheses and molecular structure of [Pt4(μ2-PPh2)4(C 6F5)4(CO)2]·2CH 2Cl2

Article abstract of DOI:10.1021/om9706469

The reaction of [NBu₄]₂[{(C₆F₅) ₂Pt(μ-PPh₂)₂Pt(μ-Cl)}₂], A, with CO in CH₂Cl₂ gives the expected dinuclear compound [NBu₄][(C₆F₅)₂Pt(μ-PPh ₂)₂PtCl(CO)], 1, which reacts with AgClO₄ (1:1 molar ratio) in CH₂Cl₂ to produce the tetranuclear cluster [Pt₄(μ-PPh₂)₄(C₆F ₅)₄-(CO)₂], 2. The analogous complex [NBu₄]₂[{(C₆F₅) ₂Pt(μ-PPh₂)₂Pd(μ-Cl)}₂], B, does not react with CO under similar conditions, but treatment of B with AgClO₄ (1:2 molar ratio, CH₂Cl₂) renders the tetranuclear compound [Pt₂Pd₂(μ-PPh₂)₃(C ₆F₅)₃(PPh₂C₆F ₅)], 3, in which the PPh₂C₆F₅ ligand is produced through an unusual M-PPh₂/M-C₆F₅ reductive coupling. Complex 3 reacts with CO in CH₂Cl₂ producing the tetranuclear complex [Pt₂Pd₂(μ-PPh₂)₂-(μ ₃-PPh(1,2-η²-Ph)-κ³P)(C ₆F₅)₃(CO)(PPh₂C₆F ₅)], 4. The molecular structures of complexes 2 and 4 have been established by X-ray crystallography.

Full text of DOI:10.1021/om9706469

Organometallics 1997, 16, 5849-5856
5849
P olyn u clea r Hom o- or Heter om eta llic
P a lla d iu m (II)-P la tin u m (II) P en ta flu or op h en yl
Com p lexes Con ta in in g Br id gin g Dip h en ylp h osp h id o
Liga n d s. 6.† Syn th eses a n d Molecu la r Str u ctu r e of
[P t4(µ2-P P h 2)4(C6F 5)4(CO)2]‚2CH2Cl2 a n d
[P t2P d 2(µ2-P P h 2)2(µ3-P P h (1,2-η2-P h )-K3P )-
‡
(C6F 5)3(CO)(P P h 2C6F 5)]‚CHCl3‚C5H12
Larry R. Falvello, J uan Fornie´s,* Consuelo Fortun˜o, Antonio Mart´ın, and
Ana P. Mart´ınez-Sarin˜ena
Departamento de Quı´mica Inorga´nica and Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received J uly 28, 1997X
The reaction of [NBu4]2[{(C6F5)2Pt(µ-PPh2)2Pt(µ-Cl)}2], A, with CO in CH2Cl2 gives the
expected dinuclear compound [NBu4][(C6F5)2Pt(µ-PPh2)2PtCl(CO)], 1, which reacts with
AgClO4 (1:1 molar ratio) in CH2Cl2 to produce the tetranuclear cluster [Pt4(µ-PPh2)4(C6F5)4-
(CO)2], 2. The analogous complex [NBu4]2[{(C6F5)2Pt(µ-PPh2)2Pd(µ-Cl)}2], B, does not react
with CO under similar conditions, but treatment of B with AgClO4 (1:2 molar ratio,
CH2Cl2) renders the tetranuclear compound [Pt2Pd2(µ-PPh2)3(C6F5)3(PPh2C6F5)], 3, in which
the PPh2C6F5 ligand is produced through an unusual M-PPh2/M-C6F5 reductive coupling.
Complex 3 reacts with CO in CH2Cl2 producing the tetranuclear complex [Pt2Pd2(µ-PPh2)2-
(µ3-PPh(1,2-η2-Ph)-κ3P)(C6F5)3(CO)(PPh2C6F5)], 4. The molecular structures of complexes 2
and 4 have been established by X-ray crystallography.
In tr od u ction
nuclear platinum or palladium carbonyl phosphido com-
plexes which are the result of these or derived reactions
and which display several interesting features. Most
of them contain several Pt-M bonds and η2-P(C6H5)-
(C6H5)-M interactions. In one of the reactions, a re-
ductive coupling between PPh2 and C6F5 to produce
PPh2C6F5, which is an unusual process, is observed.
It is well-known that phosphido groups are very
flexible ligands which are able to stabilize polynuclear
transition metal clusters.1 In the course of our current
research on phosphido palladium or platinum com-
plexes, we have synthesised the tetranuclear homo- or
heterometallic derivatives [NBu4]2[{(C6F5)2Pt(µ-PPh2)2M-
(µ-Cl)}2] (M ) Pd, Pt),2 which react easily with neutral
monodentate ligands such as phosphines, giving the di-
nuclear derivatives as a result of halide bridge cleavage.
The 31P NMR spectra of the resulting dinuclear deriva-
tives reveal that the Pt-P-M angle is rather large, i.e.,
that there is no intermetallic bonding, to be expected
for a system with a total valence electron count of 32.
In addition, we have also observed that these chloride-
containing complexes eliminate chloride, after adequate
treatment, forming the dinuclear complexes with PtfM
bonds (total valence electron count 30).
Resu lts a n d Discu ssion
Reaction of [NBu 4]2[{(C6F5)2P t(µ-P P h 2)2P t(µ-Cl)}2]
w ith CO. [NBu4]2[{(C6F5)2Pt(µ-PPh2)2Pt(µ-Cl)}2] reacts
with CO in CH2Cl2 producing Pt(µ-Cl)2Pt bridge cleav-
age and yielding the dinuclear anionic derivative
[NBu4][(C6F5)2Pt(µ-PPh2)2PtCl(CO)], 1 (see Scheme 1a).
The spectroscopic data allow an unequivocal structural
assignment for complex 1. The IR spectrum shows
characteristic absorptions of the pentafluorophenyl
groups. The ones due to the X-sensitive mode appear
as two bands (783, 776 cm-1) with similar intensities,
as expected for complexes containing two C6F5 groups
bonded to the same metal center and in mutually cis
positions.3 Absorptions due to ν(Pt-Cl), 270 cm-1, and
ν(CtO), 2075 cm-1, are also observed. The 31P NMR
spectrum of 1 can be interpreted in terms of a second-
order spin system (AB). The resonances appear upfield,
suggesting that no platinum-platinum bond is present,4
and show platinum satellites. In the 19F NMR spec-
However, preliminary studies on the reactions of the
above-mentioned tetranuclear species with CO revealed
that the reactions apparently proceeded in a different
way that had not been elucidated.
In this paper, we report the reactions of the tetra-
nuclear complexes with CO and describe several poly-
§ Part 5. See ref 7c.
‡ Dedicated to Prof. Pascual Royo on the occasion of his 60th
birthday.
X Abstract published in Advance ACS Abstracts, December 1, 1997.
(1) Baker, R. T.; Fultz, W. C.; Marder, T. B.; Williams, I. D.
Organometallics 1990, 9, 2357 and references given therein.
(2) (a) Fornie´s, J .; Fortun˜o, C.; Navarro, R.; Mart´ınez, F.; Welch, A.
J . J . Organomet. Chem. 1990, 394, 643. (b) Falvello, L. R.; Fornie´s, J .;
Fortun˜o, C.; Mart´ınez, F. Inorg. Chem. 1994, 33, 6242.
(3) Uso´n, R.; Fornie´s, J . Adv. Organomet. Chem. 1988, 288, 219.
(4) (a) Mercer, W. C.; Geoffroy, G. L.; Rheingold, A. L. Organome-
tallics 1985, 4, 1418. (b) Morrison, E. D.; Harley, A. D.; Marcelli, M.
A.; Geoffroy, G. L.; Rheingold, A. L.; Fultz, W. C. Organometallics 1984,
3, 1407. (c) Mercer, W. C.; Whittle, R. R.; Burkhardt, E. W.; Geoffroy,
G. L. Organometallics 1985, 4, 68.
S0276-7333(97)00646-8 CCC: $14.00 © 1997 American Chemical Society

5850 Organometallics, Vol. 16, No. 26, 1997
Falvello et al.
Sch em e 1
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [P t4(C6F 5)4(P P h 2)4(CO)2] (2‚2CH2Cl2)
Pt(1)-C(25)
Pt(1)-P(1)
Pt(2)-P(1)
Pt(3)-P(4)
Pt(4)-C(19)
Pt(4)-P(4)
Pt(1)-C(1)
Pt(2)-C(26)
1.917(10)
2.354(2)
2.315(2)
2.247(2)
2.056(9)
2.330(2)
2.040(8)
1.917(10)
Pt(2)-Pt(3)
Pt(3)-P(2)
Pt(4)-C(13)
Pt(1)-C(7)
Pt(2)-P(2)
Pt(3)-P(3)
Pt(3)-Pt(4)
Pt(4)-P(3)
2.6994(5)
2.264(2)
2.080(9)
2.073(9)
2.247(2)
2.237(2)
2.6882(5)
2.288(2)
C(25)-Pt(1)-C(1) 177.0(4)
C(25)-Pt(1)-C(7)
C(25)-Pt(1)-P(1)
C(7)-Pt(1)-P(1)
C(26)-Pt(2)-P(1)
89.5(4)
91.7(3)
172.2(3)
96.6(3)
C(1)-Pt(1)-C(7)
C(1)-Pt(1)-P(1)
89.1(4)
90.1(3)
C(26)-Pt(2)-P(2) 157.9(3)
P(2)-Pt(2)-P(1)
P(2)-Pt(2)-Pt(3)
P(3)-Pt(3)-P(4)
P(4)-Pt(3)-P(2)
Pt(2)-P(2)-Pt(3)
Pt(3)-P(4)-Pt(4)
105.56(8) C(26)-Pt(2)-Pt(3) 104.6(3)
53.53(6) P(1)-Pt(2)-Pt(3)
109.73(8) P(3)-Pt(3)-P(2)
147.35(8) Pt(2)-P(1)-Pt(1)
73.52(7) Pt(3)-P(3)-Pt(4)
71.91(7)
156.89(6)
102.85(8)
102.14(9)
72.90(7)
the range usually found for this kind of complex.2,5 The
angles C-Pt(1)-C and C-Pt(1)-P(1) define an almost
perfect square-planar environment for the metal atom.
The Pt(1) fragment is linked to the rest of the molecule
through the P(1)Ph2 ligand. Pt(2), Pt(3), and Pt(4) and
their environments lie in a plane, except for the P(1)
atom which is located 0.665 Å above the plane. This
plane makes a dihedral angle of 53.0° with the square
coordination plane of Pt(1). The angle Pt(1)-P(1)-Pt-
(2) is 102.14(9)°, and the Pt(1)-Pt(2) distance is 3.632-
(1) Å, excluding any kind of interaction between the
metal centers.
Pt(2) and Pt(3) are bridged by a single phosphido
ligand. The small value of the Pt(2)-P(2)-Pt(3) angle
(73.52(7)°) and the short Pt(2)-Pt(3) distance (2.6994-
(5) Å) are consistent with the presence of an interme-
tallic bond. The Pt(2) and Pt(3) environments are
distorted from square planar (Table 1).
F igu r e 1. Structure of [Pt4(µ-PPh2)4(C6F5)4(CO)2] (2)
showing the atom labeling scheme.
trum, the signals due to the p-F atoms appear to overlap
with the ones due to the m-F atoms and signals due to
the o-F atoms appear as a broad multiplet with plati-
num satellites.
The reaction of complex 1 with AgClO4 (1:1 molar
ratio) in CH2Cl2 results in the precipitation of AgCl, and
from the mother liquor after appropriate treatment, a
compound, 2, of stoichiometry [Pt2(µ-PPh2)2(C6F5)2(CO)]
is obtained. However, although this compound has the
same stoichiometry as the complexes obtained by react-
ing the analogous phosphine complexes, the structural
data reveal a different structure. Complex 2 can also
be obtained by reacting [NBu4]2[{(C6F5)2Pt(µ-PPh2)2Pt-
(µ-Cl)}2] with 2 equiv of AgClO4 and CO. The structure
of 2 has been established by an X-ray diffraction study.
Cr ysta l Str u ctu r e of [P t4(µ-P P h 2)4(C6F 5)4(CO)2]‚
2CH2Cl2 (2‚2CH2Cl2). The structure of complex 2
together with the atom labeling scheme is shown in
Figure 1. Selected bond distances and angles are listed
in Table 1. Complex 2 is a tetrametallic unit in which
the four platinum atoms are bridged by phosphide
ligands. The Pt(1)-C and Pt(1)-P(1) distances are in
Pt(3) and Pt(4) are bridged by two phosphido ligands,
the Pt(3)-Pt(4) distance being 2.6882(5) Å. The values
of the angles Pt(3)-P-Pt(4) (72.90(7)° for P(3) and
71.91(7)° for P(4)]) are small, and the P(3)-Pt-P(4)
angles (109.73(8)° for Pt(3) and 105.13(8)° for Pt(4)) are
(5) (a) Alonso, E.; Fornie´s, J .; Fortun˜o, C.; Mart´ın, A.; Orpen, A. G.
J . Chem. Soc., Chem. Commun. 1996, 231. (b) Alonso, E.; Fornie´s, J .;
Fortun˜o, C.; Toma´s, M. J . Chem. Soc., Dalton Trans. 1995, 3777.

Polynuclear Pd(II)-Pt(II) Complexes
Organometallics, Vol. 16, No. 26, 1997 5851
relatively large. This kind of geometry is commonly
found for fragments M(µ-PPh2)2M′ in which metal-
metal bonds are invoked6 and are rather similar to that
found in the complex [(C6F5)2Pt(µ-PPh2)2Pd(PPh3)].2b
Pt(4) is also bonded to two pentafluophenyl ligands, thus
completing the square-planar coordination sphere.
It is noteworthy that the structure of 2 shows phos-
phido ligands acting as bridges in three structurally
different forms. Phosphide P(1) is the only ligand
bridging the two platinum atoms, Pt(1) and Pt(2), with
no intermetallic interaction. Phosphide P(2) is the only
ligand linking Pt(2) and Pt(3), but in this case the Pt-
Pt distance is consistent with a Pt-Pt bond. Finally
Pt(3) and Pt(4) are bridged simultaneously by two
phosphide ligands, with a short intermetallic distance
as well. This structure gives a total valence electron
count of 60, which is consistent with the presence of two
Pt-Pt bonds between three Pt(II) centers in the bent-
chain cluster 2.
and 103.2°, δ31P ) -132.0 ppm for [(C6F5)2Pt(µ-PPh2)2-
Pt(phen)];2a 104.4° and 102.3°, δ31P ) -126.8 ppm for
[(C6F5)2Pt(µ-PPh2)2Pd(µ-OH)2Pt(PPh3)2]5b), we and oth-
ers9 conclude that this relationship may not always be
true. Thus, δ31P values can render important informa-
tion about M-P-M angles in singly bridged diphen-
ylphosphido or in dibridged bis(diphenylphosphido)
complexes, but single and double bridges cannot be
compared between them for this purpose.
All signals show platinum satellites, and from each
1
of the satellites, two J Pt-P values can be extracted.
1
Powell10 correlated Pt-Pµ bond lengths with J Pt-P
µ
values in closely related dinuclear systems, the longer
Pt-P bonds being associated with a decrease in the
coupling constant. Nevertheless, as he pointed out,
1J Pt-P values are very sensitive to changes in ligands
µ
on the Pt center. In agreement with this, we observed
that while the Pt(2)-P(2) distance is equal to Pt(3)-
P(4), the two 1J Pt-P(2) values are much larger than that
1
found for J Pt(3)-P(4). Hence, an unequivocal assignment
The IR spectrum of 2 shows no absorptions assignable
to ν(Pt-Cl). The X-sensitive modes of the C6F5 groups
appear as two broad absorptions of different intensities.
Moreover, complex 2 shows two sharp absorptions at
2082 and 2056 cm-1 due to the ν(CtO) stretching
modes. All of these data are in accord with the structure
of 2.
of 1J Pt-P(2) and 1J Pt-P(1) values is not possible in this case.
The formation of this tetranuclear compound instead
of the expected dinuclear derivative could be a conse-
quence of the interaction between the two moieties of
the expected dinuclear derivative, since in such a
compound the platinum center of the Pt-CO fragment
displays a Lewis acid behavior2b while both Pt-P bonds
of the same fragment behave as a Lewis base,11,12 so
that a donor-acceptor interaction could start the dimer-
ization process giving the intermediate A which could
rearrange to B and finally to 2 (see Scheme 2).
It is well-documented that a deshielding of the 31P
resonances in phosphido-bridged complexes may indi-
cate the presence of a metal-metal bond.4 The 31P
NMR spectrum of 2 in CDCl3 shows four signals at
higher frequencies than the corresponding signals from
the starting material. Signals due to P(4) and P(3) (P
atoms of PPh2 groups that bridge two platinum centers
joined by a metal-metal bond) appear at 275.7 and
257.2 ppm, respectively. Analogous chemical shifts
have been found for other complexes that show the
fragment “(C6F5)2Pt(µ-PPh2)2M” with short Pt-M
distances.2b The P(2)Ph2 group acts as a single bridging
ligand between the Pt(3) and Pt(2) centers (Pt(3)-
Pt(2) distance 2.6994(5) Å), and the signal due to P(2)
appears at 147.1 ppm, in the same region as that found
for the analogous PPh2 in [NBu4][Pt3(µ-PPh2)2(C6F5)5].5a
The signal due to P(1) appears at a lower frequency,
-6.9 ppm, in good agreement with the long Pt(1)-
Pt(2) distance and with the δ31P found for other singly
bridged µ-phosphido dinuclear complexes without metal-
metal bonds.7 A relationship between the angular
parameters at the phosphorus atom and the corre-
sponding δ31P has been previously proposed. Thus, the
closing of the M-P-M′ angle means a deshielding at
the P atom.8 In fact, the Pt(1)-P(1)-Pt(2) angle
(102.14(9)°) is the largest one in cluster 2. Nevertheless,
if we compare this angle and the δ31P for this phosphide
ligand with the M-P-M angles observed in our doubly
bridged bis(diphenylphosphido) previously reported com-
plexes, in which no metal-metal bond is present (102.7°
R ea ct ion of [NBu 4]2[{(C6F 5)2P t (µ-P P h 2)2P d (µ-
Cl)}2] w ith CO. The analogous reaction between the
heteronuclear compound and CO gives completely dif-
ferent results. When a CH2Cl2 solution of [NBu4]2-
[{(C6F5)2Pt(µ-PPh2)2Pd(µ-Cl)}2] is treated with CO (at
room temperature), in order to obtain [NBu4][(C6F5)2-
Pt(µ-PPh2)2PdCl(CO)], no reaction takes place and only
the starting material can be recovered from the mother
liquor. The carbon monoxide is not able to break the
“Pd(µ-Cl)2Pd” framework to give a Pd-CO bond. For
that reason, and aiming to prepare a polynuclear pal-
ladium/platinum complex containing carbonyl, we have
changed the synthetic strategy in order to force the
chloride elimination reaction. So, when an orange
solution of [NBu4]2[{(C6F5)2Pt(µ-PPh2)2Pd(µ-Cl)}2] in
CH2Cl2 is treated with AgClO4 (molar ratio 1:2), its
color changes to dark purple, and from the solution a
compound of stoichiometry [Pt2Pd2(µ-PPh2)3(C6F5)3-
(PPh2C6F5)], 3, is isolated in high yield (see Scheme 1c).
A CH2Cl2 solution of complex 3 reacts with CO at room
temperature to give the carbonyl cluster [Pt2Pd2(µ-
PPh2)3(C6F5)3(PPh2C6F5)(CO)], 4. The IR and 19F NMR
spectra of the two complexes 3 and 4 present some
similarities. A full structural characterization of 4 has
been carried out by X-ray diffraction, and from these
data and by comparing the spectroscopic data of 3 and
4, a reasonable structure of complex 3 can finally be
proposed.
(6) (a) Braunstein, P.; Matt, D.; Bars, O.; Louer, M.; Grandjean, D.;
Fischer, J .; Mitschler, A. J . Organomet. Chem. 1981, 213, 79. (b) Shyu,
S.-G.; Calligaris, M.; Nardin, G.; Wojcicki, A. J . Am. Chem. Soc. 1987,
109, 3617.
(7) (a) Shyu, S.-G.; Lin, P.-J .; Lin, K.-J .; Chang, M.-C.; Wen, Y.-S.
Organometallics 1995, 14, 2253. (b) Shyu, S.-G.; Hsiao, S.-M.; Lin, K.-
J .; Gau, H.-M. Organometallics 1995, 14, 4300. (c) Alonso, E.; Fornie´s,
J .; Fortun˜o, C.; Mart´ın, A.; Rosair, G. M.; Welch, A. J . Inorg. Chem.
1997, 36, 4426.
(9) Deeming, A. J .; Doherty, S. Polyhedron 1996, 15, 1175.
(10) (a) Powell, J .; Sawyer, J . F.; Stainer, M. V. R. Inorg. Chem.
1989, 28, 4461. (b) Powell, J .; Fuchs, E.; Gregg, M. R.; Phillips, J .;
Stainer, M. V. R. Organometallics 1990, 426, 247.
(11) Alonso, E. Ph.D. Thesis, University of Zaragoza, Zaragoza,
Spain, J uly 1996.
(8) Barre´, C.; Boudot, P.; Kubicki, M. M.; Moise, C. Inorg. Chem.
1995, 34, 284.
(12) Bender, R.; Braunstein, P.; Dedieu, A.; Dusausoy, Y. Angew.
Chem., Int. Ed. Engl. 1989, 28, 923.

5852 Organometallics, Vol. 16, No. 26, 1997
Falvello et al.
F igu r e 3. Schematic view of the central core of 4.
F igu r e 2. Structure of [Pt2Pd2(µ-PPh2)3(C6F5)3(PPh2C6F5)-
(CO)] (4) showing the atom labeling scheme.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [P t2P d 2(P P h 2)3(C6F 5)3{P P h 2(C6F 5)}(CO)]‚
CHCl3‚C5H12 (4‚CHCl3‚C5H12
)
Sch em e 2
Pt(1)-C(7)
Pt(1)-P(2)
Pt(2)-C(13)
Pt(2)-Pd(1)
Pd(1)-P(2)
Pd(2)-P(2)
Pt(1)-C(1)
Pt(1)-Pd(1)
Pt(2)-P(3)
2.058(8)
2.371(2)
2.065(8)
2.8718(7)
2.376(2)
2.351(2)
2.100(9)
2.7513(7)
2.285(2)
Pd(1)-P(1)
Pd(1)-Pd(2)
Pd(2)-C(37)
Pt(1)-P(1)
Pt(2)-C(73)
Pt(2)-Pd(2)
Pd(1)-P(3)
Pd(2)-P(4)
Pd(2)-C(38)
2.220(2)
2.7983(9)
2.425(8)
2.305(2)
1.922(9)
2.7063(7)
2.249(2)
2.342(2)
2.649(8)
C(7)-Pt(1)-C(1)
C(1)-Pt(1)-P(1)
C(1)-Pt(1)-P(2)
C(73)-Pt(2)-C(13)
C(13)-Pt(2)-P(3)
84.1(3)
166.5(2)
84.3(2)
94.4(4)
97.4(2)
C(7)-Pt(1)-P(1)
C(7)-Pt(1)-P(2)
P(1)-Pt(1)-P(2)
C(73)-Pt(2)-P(3)
C(73)-Pt(2)-Pd(2)
P(3)-Pt(2)-Pd(2)
86.8(2)
166.6(2)
105.68(7)
164.9(3)
69.3(3)
100.28(5)
108.31(8)
142.81(6)
53.29(5)
118.0(2)
97.38(6)
72.60(6)
78.60(7)
110.3(3)
111.0(3)
119.6(3)
C(13)-Pt(2)-Pd(2) 161.3(2)
P(1)-Pd(1)-P(3)
P(3)-Pd(1)-P(2)
P(3)-Pd(1)-Pd(2)
107.61(8) P(1)-Pd(1)-P(2)
143.73(8) P(1)-Pd(1)-Pd(2)
98.49(6) P(2)-Pd(1)-Pd(2)
Pt(1)-Pd(1)-Pd(2) 101.71(2) P(4)-Pd(2)-C(37)
P(4)-Pd(2)-C(38)
Pd(1)-P(1)-Pt(1)
Pt(1)-P(2)-Pd(1)
C(37)-P(2)-Pd(2)
C(37)-P(2)-C(43)
C(43)-P(2)-Pt(1)
101.9(2)
74.86(7) Pd(2)-P(2)-Pd(1)
70.85(6) Pd(1)-P(3)-Pt(2)
69.8(2)
107.7(4)
114.5(3)
P(2)-Pd(2)-Pt(2)
C(37)-P(2)-Pt(1)
C(43)-P(2)-Pd(2)
C(43)-P(2)-Pd(1)
Pt(1), C(1), C(7), P(1), Pd(1), P(3), Pt(2), C(73), and O
lie almost in a plane (see Figure 3), with a maximum
deviation for the Pd(1) center (0.203 Å). P(2) is located
below this plane, at 0.517 Å. Complex 4 can be regarded
as the union of the “Pd(2)(PPh2C6F5)” fragment to the
planar moiety described above through metal-metal
interactions and a P(2)Ph2 bridging ligand. Pd(1), Pd-
(2), and Pt(2) form a nearly equilateral triangle. The
internal angles are Pd(1)-Pt(2)-Pd(2) 60.13(2)°,
Pt(2)-Pd(1)-Pd(2) 57.00(2)°, and Pt(2)-Pd(2)-Pd(1)
62.87(2)°, and the intermetallic distances are Pt(2)-
Pd(1) 2.8718(7), Pd(1)-Pd(2) 2.7983(9), and Pt(2)-
Pd(2) 2.7063(7) Å, all three within bonding distance.13
Pd(2) is also bonded to P(2) with an interatomic distance
of 2.351(2) Å. The geometry around atom P(2) is very
unusual, since it is five-coordinate12,14 and acts as a
triple bridge between three of the metal atoms (Pt(1),
Cr yst a l St r u ct u r e of [P t 2P d 2(µ-P P h 2)3(C6F 5)3-
(P P h 2C6F 5)(CO)]‚CHCl3‚C5H12 (4‚CHCl3 ‚C5H12). The
structure of complex 4 together with the atom labeling
scheme is shown in Figures 2 and 3. Selected bond
distances and angles are listed in Table 2. Complex 4
is a tetrametallic Pt2Pd2 unit in which the four metal
atoms are bridged by phosphide ligands. The atoms
(13) (a) Berry, D. E.; Bushnell, G. W.; Dixon, K. R.; Moroney, P. M.;
Wan, C. Inorg. Chem. 1985, 24, 2634. (b) Leoni, P.; Manetti, S.;
Pasquali, M.; Albinati, A. Inorg. Chem. 1996, 35, 6045. (c) Bender, R.;
Braunstein, P.; Dedieu, A.; Ellis, P. D.; Huggins, B.; Harvey, P. D.;
Sappa, E.; Tiripicchio, A. Inorg. Chem. 1996, 35, 1223.

Polynuclear Pd(II)-Pt(II) Complexes
Organometallics, Vol. 16, No. 26, 1997 5853
Pd(1), and Pd(2)) of the complex. The three P(2)-M
distances are almost equal (2.371(2) Å for Pt(1), 2.376-
(2) Å for Pd(1), and 2.351(2) Å for Pd(2)) and longer than
the other phosphide-metal distances present in 4 (see
Table 2). Moreover, there are also relatively short
distances between the Pd(2) center and two carbon
atoms of one phenyl ring of the P(2) phosphide ligand,
indicating a possible η2-arene interaction. The com-
plexes [Ru4(µ-H)(CO)10(µ-PPh2)(µ-PPh2C6H4)]15 and
[NBu4][Pt3(µ-PPh2)2(C6F5)5]5a show a similar unusual
bridging phosphide in which there is an M-P distance
that is longer than the other two, with the metal center
M simultaneously bonded to one of the phenyl rings of
the phosphide through an η2-arene interaction. How-
ever, the Pd(2)-C distances in 4 are 2.425(8) Å for C(37)
and 2.649(8) Å for C(38), longer than the ones found in
the complexes mentioned above, indicating that in 4 the
η2-arene interaction is weaker. The coordination sphere
of the Pd(2) center is completed by a PPh2C6F5 ligand
which, as we will see below, is also present in the
starting material 3, as revealed by its NMR spectra.
Pt(2) lies in the center of a square planar environment
formed by the P(3)PPh2 phosphide, one carbonyl, and
one pentafluorophenyl ligand, the fourth coordination
position being taken by the Pd(2) atom. This geometry
forces the C(13) atom to be located 1.309 Å above the
main molecular plane described above. Phosphide P(3)
bridges the Pt(2) and Pd(1) centers. The angle Pt(2)-
P(3)-Pd(1) is small (78.60(7)°), consistent with the short
intermetallic distance.
The environment of the Pd(1) atom is very distorted.
It is doubly bridged to Pt(1) by two phosphide ligands.
The geometry of the Pd(1)(µ-PPh2)2Pt(1) fragment, small
Pd-P-Pt and large P-M-P angles, is commonly found6
for systems in which short intermetallic distances are
present. For 4, the Pt(1)-Pd(1) distance is 2.7513(7)
Å. Pt(1) is also bonded to two pentafluophenyl ligands,
thus completing the square planar coordination sphere.
If the phenyl-platinum interaction observed in 4
represents a classical two electron bonding interaction,
this structure gives a total valence electron count of 58,
which would be in agreement with the presence of three
metal-metal bonds. However, the crystal structure
reveals the existence of four short metal-metal dis-
tances, in agreement with a total valence electon count
of 56. The values of these distances are quite similar,
with a difference of 0.17 Å between the longest and the
shortest. As can be seen, complex 4 shows some
remarkable features: (i) the four metal centers present
mixed formal oxidation states, since they have to supply
an overall charge of 6+, (ii) a PPh2 group acts as a triply
bridging ligand. Only rarely12,14,15 do such ligands
display µ3-PR2 coordination with three metal centers
involved, and (iii) a new phosphine ligand, PPh2(C6F5),
is coordinated to a palladium center.
cies (1515 and 977 cm-1), the latter probably being due
to the C6F5 group bonded to the P atom. An absorption
at 2025 cm-1 is due to ν(CtO). This value is lower than
the ones found for the corresponding ν(CtO) in complex
2, indicating a larger degree of π-back donation in the
Pt-CO bond. The 19F NMR spectrum of 4 shows, in
the usual region of o-F atoms, five signals with platinum
satellites and an intensity ratio of 2:1:1:1:1. The most
intense signal is assigned to o-F of the C6F5 group cis
to the CO group and the other ones to the four in-
equivalent o-F atoms of the two C6F5 groups mutually
cis. Signals due to the m-F and p-F atoms of these C6F5
groups appear, as expected, from -160 to -165 ppm,
but an unambiguous assignment for all these m-F and
p-F cannot be carried out. Moreover, the spectrum
shows signals due to another type of C6F5 group. The
ones due to o-F (-127.1 ppm, no platinum satellites)
and p-F (-150.2 ppm) appear in a striking region, while
the signal due to m-F is in the same region as the m-F
and p-F signals of the other C6F5 groups. These signals
can be assigned to the phosphine pentafluorophenyl
ring. Similar chemical shifts have been observed in
other pentafluorophenyl organic ligands.16
The 31P NMR spectrum of 4 shows four signals. Three
of them, with platinum satellites, appear from 270 to
150 ppm and are assigned to P atoms of the PPh2
groups. These downfield chemical shifts are consistent
with short metal-metal distances and small M-P-M
angles in the “M(µ-PPh2)xM” (x ) 1 or 2) systems. The
signal due to the P atom of the PPh2C6F5 phosphine
ligand appears at 23.9 ppm and has no platinum
satellites.
Str u ctu r a l Ch a r a cter iza tion of 3. All our attemps
to grow crystals of 3 suitable for an X-ray study have
proven unsuccessful. So, the structure of complex 3 can
only be established on the basis of spectroscopic data
and by comparing it with the structure of 4.
The IR spectrum of complex 3 shows two broad
absorptions of different intensities which can be as-
signed to the X-sensitive mode of the C6F5 groups. As
in complex 4, beside the strong signals around 1500 and
950 cm-1, two other absorptions of lower intensity are
observed at higher frequencies (1516 and 978 cm-1),
indicating that, as in 4, the PPh2C6F5 ligand is present
in complex 3.
The 19F NMR spectrum of 3 shows three signals with
platinum satellites and an intensity ratio of 2:2:2 due
to the o-F atoms of the three C6F5 groups bonded to the
platinum centers. Signals due to the m-F and p-F atoms
of these C6F5 groups appear overlapped in the range
from -160 to -165 ppm. Moreover, there are two
signals with an intensity ratio of 2:1 at ca. -130 and
-150 ppm. The chemical shifts of these signals indicate
that complex 3, as with complex 4, must contain a
PPh2C6F5 ligand.
The 31P NMR spectrum of 3 shows four signals in the
same region as that for complex 4. Unlike complex 4,
all of these signals show platinum satellites. This
indicates that in complex 3 the PPh2C6F5 ligand has to
be bonded to a Pt center.
In the IR spectrum of complex 4, the X-sensitive
modes of the C6F5 groups appear as two broad absorp-
tions with different intensities. Besides the strong
signals around 1500 and 950 cm-1, two other absorp-
tions of lower intensity are observed at higher frequen-
A reasonable structure for complex 3, which agrees
with all of these spectroscopic data, is schematized in
(14) (a) Gol, F.; Knuppel, P. C.; Stelzer, O.; Sheldrick, W. S. Angew.
Chem., Int. Ed. Engl. 1988, 27, 956. (b) Brauer, D. J .; Knuppel, P. C.;
Stelzer, O. J . Chem. Soc., Chem. Commun. 1988, 551. (c) J ones, R. A.;
Stuart, A. L.; Wright, T. C. J . Am. Chem. Soc. 1983, 105, 7459.
(15) Corrigan, J . F.; Doherty, S.; Taylor, N. J .; Carty, A. J . J . Am.
Chem. Soc. 1992, 114, 7557.
(16) (a) Uso´n, R.; Fornie´s, J .; Espinet, P.; Lalinde, E.; J ones, P. G.;
Sheldrick, G. M. J . Chem. Soc., Dalton Trans. 1982, 2389. (b) Uso´n,
R.; Fornie´s, J .; Espinet, P.; Lalinde, E. J . Organomet. Chem. 1983,
254, 371.

5854 Organometallics, Vol. 16, No. 26, 1997
Falvello et al.
3-nitrobenzyl alcohol (3-NOBA) as the matrix. Literature
methods were used to prepare the starting complexes [NBu4]2-
[{(C6F5)2Pt(µ-PPh2)2M(µ-Cl)}2].2a
P r ep a r a tion of [NBu 4][(C6F 5)2P t(µ-P P h 2)2P tCl(CO)] (1).
CO was bubbled into a CH2Cl2 (10 mL) solution of [NBu4]2-
[{(C6F5)2Pt(µ-PPh2)2Pt(µ-Cl)}2] (400 mg, 0.146 mmol) at room
temperature for 20 min. The resulting solution was treated
with 20 mL of n-hexane, and CO was bubbled for 15 min so
that an oily residue was obtained. The stirring of this oily
residue for 2 h resulted in the precipitation of a white solid,
which was filtered off and washed with n-hexane (362 mg, 89%
yield). Anal. Calcd for C53ClF10H56NOP2Pt2: C, 45.45; H, 4.0;
N, 1.0. Found: C, 45.75; H, 4.05; N, 1.0. ΛM ) 102 Ω-1 cm2
mol-1. IR (Nujol): 783, 776 cm-1 (X-sensitive, C6F5); 2075 cm-1
(ν(CtO)). FAB-MS: m/ z 1130 ([M - CO]-). 19F NMR (20 °C,
F igu r e 4. Schematic representation of the structure
proposed for [Pt2Pd2(µ-PPh2)3(C6F5)3(PPh2C6F5)] (3).
Figure 4, in which probably one of the palladium centers
has to display two η2-C6H5-Pd weak interactions. The
formation of complex 3 is most unusual since it re-
quires a reductive coupling between a phosphido ligand
and a pentafluorophenyl group to afford a tertiary
phosphine, which is a very rare process. In fact, it is
well-known that tertiary phosphine ligands can be
converted thermally to phosphido bridging species
through the breaking of a P-C bond and formation of
new M-P and M-C bonds.13c,17 Examples of reductive
coupling between a phosphido group and a one-electron
donor ligand to afford a tertiary phosphine are rather
scarce.18 Braunstein et al. have recently reported19 the
first cluster-mediated conversion of M-C6H5 into a
P-C6H5 bond, a coupling reaction between a PPh2
bridge and a phenyl group to give a PPh3 ligand. Since
it is well-known that the M-C6F5 bonds are more stable
than the corresponding M-C6H5 bonds,20 the formation
of complex 3 throught a reductive coupling is most
unusual.
Finally, it is also noteworthy that the reaction of 3
with CO, which should result in the breaking of the
weak η2-C6H5-Pd interactions, does simultaneously
produce a migration of the phosphine ligand to the
palladium center. The ability of CO to act as a bridging
ligand21 and the higher stability of the Pt-CO bond as
compared to Pd-CO could be the reason for this phos-
phine migration. In addition, it is also noteworthy that
although the reaction is carried out in an excess of CO,
only one of the proposed η2-C6H5-Pd interactions is
broken.
3
acetone-d6, 282.4 MHz) δ: -116.1(4 o-F, J Pt-F ) 325.2 Hz),
-167.2 to -168.6 (6 m-F + p-F). 31P{1H} NMR (20 °C, acetone-
2
d6, 121.4 MHz) δ: -137.1 (1J Pt-P ) 1941.6 Hz, J P-P ) 147.4
Hz), -142.9 (1J Pt-P ) 1958.7, 1821.7 Hz).
P r ep a r a tion of [P t4(µ-P P h 2)4(C6F 5)4(CO)2] (2). To a
stirred solution of 1 (200 mg, 0.143 mmol) in CH2Cl2 (15
mL), AgClO4 was added (31 mg, 0.149 mmol). After 3 h of
stirring, the mixture was filtered off and the solvent was
removed under vacuum. i-PrOH (8 mL) was added, and by
stirring, an orange solid 2 crystallized, which was filtered off
and washed with 1 mL of i-PrOH (104 mg, 65%). Anal. Calcd
for C74F20H40O2P4Pt4: C, 39.6; H, 1.8. Found: C, 39.4; H, 1.8.
IR (Nujol): 796, 782 cm-1 (X-sensitive, C6F5); 2082, 2056 cm-1
(ν(CtO)). FAB-MS: m/ z 2189 ([M - 2CO]+). 19F NMR (20
3
°C, CDCl3, 282.4 MHz) δ: -117.1 (2 o-F, J Pt-F ) 366.2 Hz),
-118.0 (2 o-F, 3J Pt-F ) 304.2 Hz), -119.2 (4 o-F, 3J Pt-F ) 300.7
Hz), -159.4 (2 m-F), -160.2 (1 p-F), -161.2 (1 p-F), -163.0 (4
m-F), -163.4 (2 m-F), -164.1 (2 p-F). 31P{1H} NMR (20 °C,
CDCl3, 121.4 MHz) δ: 275.7 (ddd, P(4), 1J Pt(4)-P(4) ) 1097.8 Hz,
2
2
1J Pt(3)-P(4) ) 1914.2 Hz, J P(4)-P(2) ) 119.6 Hz, J P(4)-P(3) ) 64.3
Hz, 3J P(4)-P(1) ) 28.9 Hz), 257.2 (pseudo t, br, P(3), 1J Pt(4)-P(3)
)
)
1
1
1312.7 Hz, J Pt(3)-P(3) ) 2104.4 Hz), 147.1 (dd, P(2), J Pt-P(2)
2
2
2875.4, 2792.7 Hz, J Pt(4)-P(2) ) 81.5 Hz, J P(4)-P(2) ) 119.6 Hz,
2J P(3) or P(1)-P(2) ) 7.3 Hz), -6.9 (s very br, P(1), 1J Pt-P(1) ) 2652.3,
2
1741.2 Hz, J Pt(3)-P(1) ) 237.9 Hz).
P r ep a r a tion of [P t2P d 2(µ-P P h 2)3(C6F 5)3(P P h 2C6F 5)] (3).
To a CH2Cl2 solution (15 mL) of [NBu4]2[{(C6F5)2Pt(µ-PPh2)2-
Pd(µ-Cl)}2] (500 mg, 0.195 mmol) was added AgClO4 (95 mg,
0.458 mmol). After 3 h of stirring, the mixture was filtered
off and the solution was evaporated almost to dryness. The
addition of i-PrOH (10 mL) caused the precipitation of a pur-
ple solid 3, which was filtered off and washed with small
portions (2 × 1 mL) of i-PrOH (314 mg, 80%). Anal. Calcd
for C72F20H40P4Pd2Pt2: C, 43.0; H, 2.0. Found: C, 43.1; H, 1.8.
IR (Nujol): 1516, 978 cm-1 (C6F5); 791, 780 cm-1 (X-sensitive,
C6F5). FAB-MS: m/ z 2012 ([M]+). 19F NMR (20 °C, CDCl3,
Exp er im en ta l Section
Gen er a l Com m en ts. C, H, and N analyses were per-
formed with a Perkin-Elmer 240B microanalyzer. IR spectra
were recorded on a Perkin-Elmer 599 spectrophotometer (Nujol
mulls between polyethylene plates in the range 4000-200
cm-1). NMR spectra were recorded on a Varian Unity 300
instrument with CFCl3 and 85% H3PO4 as external references
for 19F and 31P, respectively. Conductivities (acetone, c ≈ 5 ×
10-4 M) were measured with a Philips PW 9509 conductimeter.
Mass spectra were recorded on a VG-Autospec spectrometer
operating at 30 kV, using the standard Cs-ion FAB gun and
3
282.4 MHz) δ: -115.9 (2 o-F, J Pt-F ) 307.8 Hz), -118.3 (2
3
3
o-F, J Pt-F ) 395.1 Hz), -118.6 (2 o-F, J Pt-F ) 336.9 Hz),
-130.4 (2 o-F, PPh2C6F5), -150.0 (1 p-F, PPh2C6F5), -162.4
(2 m-F, PPh2C6F5), -161.4 and -164.0 (9 m-F + p-F). 31P-
{1H} NMR (20 °C, CDCl3, 121.4 MHz) δ: 261.8 (s, br, 1J Pt-P
1595.5 Hz), 190.6 (d, br, J Pt-P ) 1227.5 Hz, J P-P ) 70.9 Hz),
)
1
1
139.6 (dm, br, J Pt-P ) 2553.7 Hz, J P-P ≈ 360 Hz), 5.7 (d,
1
PPh2C6F5, J Pt-P ) 2843.6 Hz, J P-P ) 363.8 Hz).
P r epar ation of [P t2P d2(µ-P P h 2)3(C6F5)3(P P h 2C6F5)(CO)]
(4). CO was bubbled through a CH2Cl2 (8 mL) solution of 3
(100 mg, 0.050 mmol) at room temperature for 20 min.
n-Hexane (20 mL) was added to the resulting solution, and
then CO was bubbled through the solution for 20 min. After
filtration, the solution was left to stand in the freezer (-18
°C) for 1 week. The resulting purple solid was filtered off and
washed with 2 × 1 mL of cold n-hexane (4, 50 mg, 49%). Anal.
Calcd for C73F20H40OP4Pd2Pt2: C, 43.0; H, 2.0. Found: C, 42.8;
H, 1.8. IR (Nujol): 1515, 977 cm-1 (C6F5); 790, 779 cm-1 (X-
(17) (a) Dubois, R. A.; Garrou, P. E. Organometallics 1986, 5, 460.
(b) Shiu, K.-B.; J ean, S.-W.; Wang, H.-J .; Wang, S.-L.; Liao, F.-L.;
Wang, J .-C.; Liou, L.-S. Organometallics 1997, 16, 114.(c) Garc´ıa, G.;
Garc´ıa, M. E.; Melo´n, S.; Riera, V.; Ruiz, M. A.; Villafan˜e, F. Organo-
metallics 1997, 16, 624.
(18) (a) Shulman, P. M.; Burkhardt, E. D.; Lundquist, E. G.; Pilato,
R. S.; Geoffroy, G. L.; Rheingold, A. L. Organometallics 1987, 6, 101.
(b) Blum, O.; Frolow, F.; Milstein, D. J . Chem. Soc., Chem. Commun.
1991, 258. (c) Kong, K. C.; Chen, C. H. J . Am. Chem. Soc. 1991, 113,
6313.
(19) Archambault, C.; Bender, R.; Braunstein, P.; De Cian, A.;
Fischer, J . J . Chem. Soc., Chem. Commun. 1996, 2729.
(20) Uso´n, R.; Fornie´s, J .; Toma´s, M. J . Organomet. Chem. 1988,
358, 525.
(21) Oudet, P.; Mo¨ıse, C; Kubicki, M. M. Inorg. Chim. Acta 1996,
247, 263.

Polynuclear Pd(II)-Pt(II) Complexes
Organometallics, Vol. 16, No. 26, 1997 5855
Ta ble 3. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
complex
2‚2CH2Cl2
4‚CHCl3.C5H12
empirical formula
unit cell dimens
a (Å)
b (Å)
c (Å)
C74H40F20O2P4Pt4‚2CH2Cl2
C73H40F20OP4Pd2Pt2‚CHCl3‚C5H12
17.9838(14)
23.281(2)
19.7896(15)
90
97.146(14)
90
15.227(2)
15.2923(12)
17.229(2)
87.625(8)
84.326(9)
85.793(7)
3979.1(7), 2
0.71073
R (deg)
â (deg)
γ (deg)
volume (Å3), Z
wavelength (Å)
temperature (K)
radiation
8221.1(11), 4
150(1)
150(1)
graphite monochromated Mo KR
cryst syst
monoclinic
triclinic
space group
cryst dimens (mm)
P21/n
P1h
0.70 × 0.50 × 0.30
0.50 × 0.40 × 0.20
abs coeff (mm-1
)
7.082
4.222
transmission factors
abs corr
diffractometer
2θ range for data collection (deg)
no. of reflns collected
no. of independent reflns
refinement method
goodness-of-fit on F2
final R indices [I > 2σ(I)]a
1.000, 0.255
ψ scans
Enraf-Nonius CAD4
4.0-50.0 (+h, +k, (l)
14 906
0.989, 0.603
ψ scans
Siemens P4
4.0-50.0 (+h, (k, (l)
14 549
14 409 [R(int) ) 0.0309]
13 975 [R(int) ) 0.0465]
full-matrix least-squares on F2
1.068
1.023
R1 ) 0.0422
wR2 ) 0.1066
R1 ) 0.0601
wR2 ) 0.1193
R1 ) 0.0435
wR2 ) 0.0866
R1 ) 0.0781
wR2 ) 0.1043
R indices (all data)
a
2
4
wR2 ) [∑w(Fo - Fc2)2/∑wFo
]
0.5; R1 ) ∑||Fo| - |Fc||/∑|Fo|.
sensitive, C6F5). FAB-MS: m/ z 2012 ([M - CO]+). 19F NMR
latter two, interatomic bond distances and angles were con-
strained to idealized geometries. Full-matrix least-squares
refinement of this model against F2 converged to the final
residual indices given in Table 3. Weights, w, were set equal
to [σc2(Fo2) + (aP)2 + bP]-1, where P ) [0.333 max{Fo2,0} +
3
(20 °C, CDCl3, 282.4 MHz) δ: -114.0 (2 o-F, J Pt-F ) 382.0
Hz), -116.3 (1 o-F, 3J Pt-F ) 290.1 Hz), -118.0 (1 o-F, 3J Pt-F
)
3
355.0 Hz), -119.1 (1 o-F, J Pt-F ) 280.2 Hz), -119.7 (1 o-F,
3J Pt-F ) 295.5 Hz), -127.1 (2 o-F, PPh2C6F5), -150.2 (1 p-F,
PPh2C6F5), -160.3 (2 m-F), -161.0 (2 m-F), -161.5 (1 p-F),
-163.2 to -164.6 (6 m-F + p-F). 31P{1H} NMR (20 °C, CDCl3,
2
0.667Fc2], σc2(Fo2) is the variance in Fo due to counting
statistics, and a ) 0.0559 and b ) 81.559 were chosen to
minimize the variation in S as a function of |Fo|. Final
difference electron density maps showed 37 peaks above 1 e
Å-3 (max 2.64; largest difference hole -1.88), all of them lying
within 1.12 Å of the platinum atoms. Most of these peaks (31)
have an electron density lower than 1.88 e Å-3, and their
presence can be explained on the basis of residual uncorrected
absorption (the absorption coefficient is 7.082 mm-1).
1
121.4 MHz) δ: 266.9 (s, very br, P(1), J Pt(1)-P(1) ) 1567.1 Hz),
1
2
174.4 (ddd br, P(2), J Pt(1)-P(2) ) 1239.9 Hz, J P(2)-P(4) ) 140.2
2
2
Hz, J P(2)-P(3) ) 92.1 Hz, J P(2)-P(1) ) 17.8 Hz), 152.7 (dd, P(3),
1J Pt(2)-P(3) ) 2566.5 Hz, J Pt(1)-P(3) ) 59.1 Hz, J P(2)-P(3) ) 92.1
2
2
2
2
Hz, J P(1)-P(3) ) 35.0 Hz), 23.9 (dd, P(4), J P(2)-P(4) ) 140.2 Hz,
3J P(4)-P(1) ) 15.1 Hz).
P r ep a r a tion of Cr ysta ls of 2 a n d 4 for X-r a y Str u ctu r e
Deter m in a tion s. Suitable crystals of 2 were obtained by slow
diffusion of n-hexane into a solution of 0.025 g of the complex
in CH2Cl2. Suitable crystals of 4 were obtained by slow
diffusion of n-pentane into a solution of 0.025 g of the complex
in CHCl3.
Cr ysta l Str u ctu r e An a lysis of [P t2P d 2(P P h 2)3(C6F 5)3-
{P P h 2(C6F 5)}(CO)] ‚CHCl3‚C5H12 (4‚CHCl3‚C5H12). Crystal
data and other details of the structure analysis are presented
in Table 3. A crystal of 4 was mounted at the end of a glass
fiber and held in place with a fluorinated oil. Unit cell
dimensions were determined from 37 centered reflections in
the range 20° < 2 θ < 30°. Three check reflections remeasured
after every 297 ordinary reflections showed no decay of the
crystal over the period of data collection. An absorption
correction was applied based on 242 azimuthal scan data. The
structure was solved by Patterson and Fourier methods. All
calculations were carried out using the program SHELXL-93.22
All non-hydrogen atoms were assigned anisotropic displace-
ment parameters and refined without positional constraints,
except for the solvent atoms. The hydrogen atoms of the
complex were constrained to idealized geometries and assigned
isotropic displacement parameters of 1.2Uiso of their attached
carbon (1.5Uiso for the methyl hydrogen atoms). Whereas the
positions and thermal parameters of the atoms of the metal
complex were found and refined without difficulty, the electron
density corresponding to the solvent molecules was very
diffuse. The model that gives the best results consists of one
molecule of n-pentane disordered over two positions with 0.5
occupancy each and one molecule of CHCl3 disordered over
three positions with 0.333 occupancy each. Both solvents had
been used in the obtention of the crystals, and signals of both
Cr yst a l St r u ct u r e An a lysis of [P t 4(C6F 5)4(P P h 2)4-
(CO)2]‚2CH2Cl2 (2‚2CH2Cl2). Crystal data and other details
of the structure analysis are presented in Table 3. A crystal
of 2 was mounted at the end of a quartz fiber and held in place
with a fluorinated oil. Unit cell dimensions were determined
from 25 centered reflections in the range 22.8° < 2 θ < 31.7°.
Three check reflections remeasured after every 2 h showed
no decay of the crystal over the period of data collection. An
absorption correction was applied based on 555 azimuthal scan
data. The structure was solved by Patterson and Fourier
methods. All calculations were carried out using the program
SHELXL-93.22 All non-hydrogen atoms were assigned aniso-
tropic displacement parameters and refined without positional
constraints. The hydrogen atoms of the complex were con-
strained to idealized geometries and assigned isotropic dis-
placement parameters of 1.2Uiso of their attached atom. Four
molecules of the dichloromethane solvent were found (con-
firmed by 1H NMR spectroscopy), of which one (C(76), Cl(3),
and Cl(4)) was assigned 0.5 occupancy and two (C(77), Cl(5),
and Cl(6); C(78), Cl(7), and Cl(8)) 0.25 occupancy. For the
1
were observed in the H NMR spectrum of the crystals. The
(22) Sheldrick, G. M. SHELXL-93, a program for crystal structure
determination; University of Go¨ttingen, Go¨ttingen, Germany, 1993.
interatomic distances and angles in the solvent molecules were

5856 Organometallics, Vol. 16, No. 26, 1997
Falvello et al.
constrained to idealized geometries, and the anisotropic ther-
mal parameter of the carbon and chlorine atoms of each
molecule were constrained to be the same. No attempts to
include the solvent hydrogen atoms were made. Full-matrix
least-squares refinement of this model against F2 converged
to the final residual indices given in Table 3. Weights, w, were
set equal to [σc2(Fo2) + (aP)2 + bP]-1, where P ) [0.333 max-
Ack n ow led gm en t. We thank the Direccio´n General
de Ensen˜anza Superior (Spain) for financial support
(Project Nos. PB95-0003-CO2-01 and PB95-0792).
Su p p or tin g In for m a tion Ava ila ble: Tables of full atomic
positional and equivalent isotropic displacement parameters,
anisotropic displacement parameters, full bond distances and
bond angles, and hydrogen coordinates and isotropic displace-
ment parameters for the crystal structures of complexes 2 and
4 (29 pages). Ordering information is given on any current
masthead page.
2
{Fo2,0} + 0.667Fc2], σc2(Fo2) is the variance in Fo due to
counting statistics, and a ) 0.0369 and b ) 14.87 were chosen
to minimize the variation in S as a function of |Fo|. Final
difference electron density maps showed six peaks above 1 e
Å-3 (1.26-1.05 e Å-3; largest difference hole -1.06), all of them
located in the solvent area.
OM9706469