Synthesis and structure of [Pt3(μ-dppm)2(μ-PPh2)L 2](O3SCF3) (dppm = bis(diphenylphosphino)methane; L = CO, t-BuNC)

Article abstract of DOI:10.1021/om980635v

Treatment of [Pt₂(μ-dppm)₂Cl₂] with 2 mequiv of AgO₃SCF₃ and bicyclo[2.2.1]hept-2-ene, respectively, in MeOH/CH₂Cl₂ results in a P-C cleavage of one dppm ligand to give [Pt₂-(μ-dppm)(μ-PPh₂)(η ²-bicyclo[2.2.1]hept-2-ene)₂](O₃SCF ₃) (1a) and the methoxyphosphonium salt [PMePh₂(OMe)](O₃SCF₃). Treatment of 1a with CO (1 atm) or 2 mequiv of t-BuNC gives [Pt₂(μ-dppm)(μ-PPh₂)L₂](O ₃SCF₃) where L = CO (1b) or t-BuNC (1c). The reaction of 1b or le with 1 mequiv of dppm and [Pt(η²-bicyclo[2.2.1]hept-2-ene)₃], respectively, gives [Pt₃(η-dppm)₂(μ-PPh₂)L ₂](O₃SCF₃) where L = CO (2a) or t-BuNC (2b). The new compounds were characterized by multinuclear NMR, FAB-MS, IR, and chemical analysis, 1a, 2a, and 2b additionally by single-crystal X-ray diffraction. In la, the orientation of the C=C double bonds is nearly in plane with the other ligands coordinated to the Pt atoms. The molecular structures of 2a and 2b show Pt₃ triangles whose edges are spanned by two dppm ligands and one PPh₂ ligand. There are bonds between the platinum atoms bridged by the dppm ligands (2.6456(8) and 2.6733(6) A? for 2a and 2.6463(11) and 2.6534(12) A? for 2b) while the separations of the Pt atoms bridged by the PPh₂ ligand are very long (2a, 3.5949(6) A?; 2b, 3.470(1) A?) and are clearly considered as nonbonding. The CO or t-BuNC ligands are coordinated terminally to the Pt atoms bridged by the PPh₂ ligand. The P atom of the phosphido group exhibits a short intramolecular contact to the third Pt atom of 2.954(3) A? (2a) or 2.933(5) A? (2b), which is significantly below the sum of the van der Waals radii of phosphorus and platinum.

Full text of DOI:10.1021/om980635v

5640
Organometallics 1998, 17, 5640-5646
Syn th esis a n d Str u ctu r e of
[P t3(µ-d p p m )2(µ-P P h 2)L2](O3SCF 3) (d p p m )
Bis(d ip h en ylp h osp h in o)m eth a n e; L ) CO, t-Bu NC)
Helmuth Wachtler,† Walter Schuh,† Karl-Hans Ongania,‡ Klaus Wurst,† and
Paul Peringer*,†
Institut fu¨r Allgemeine, Anorganische und Theoretische Chemie und Institut fu¨r Organische
Chemie, Universita¨t Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria
Received J uly 27, 1998
Treatment of [Pt2(µ-dppm)2Cl2] with 2 mequiv of AgO3SCF3 and bicyclo[2.2.1]hept-2-ene,
respectively, in MeOH/CH2Cl2 results in a P-C cleavage of one dppm ligand to give [Pt2-
(µ-dppm)(µ-PPh2)(η2-bicyclo[2.2.1]hept-2-ene)2](O3SCF3) (1a ) and the methoxyphosphonium
salt [PMePh2(OMe)](O3SCF3). Treatment of 1a with CO (1 atm) or 2 mequiv of t-BuNC gives
[Pt2(µ-dppm)(µ-PPh2)L2](O3SCF3) where L ) CO (1b) or t-BuNC (1c). The reaction of 1b or
1c with 1 mequiv of dppm and [Pt(η2-bicyclo[2.2.1]hept-2-ene)3], respectively, gives [Pt3(µ-
dppm)2(µ-PPh2)L2](O3SCF3) where L ) CO (2a ) or t-BuNC (2b). The new compounds were
characterized by multinuclear NMR, FAB-MS, IR, and chemical analysis, 1a , 2a , and 2b
additionally by single-crystal X-ray diffraction. In 1a , the orientation of the CdC double
bonds is nearly in plane with the other ligands coordinated to the Pt atoms. The molecular
structures of 2a and 2b show Pt3 triangles whose edges are spanned by two dppm ligands
and one PPh2 ligand. There are bonds between the platinum atoms bridged by the dppm
ligands (2.6456(8) and 2.6733(6) Å for 2a and 2.6463(11) and 2.6534(12) Å for 2b) while the
separations of the Pt atoms bridged by the PPh2 ligand are very long (2a , 3.5949(6) Å; 2b,
3.470(1) Å) and are clearly considered as nonbonding. The CO or t-BuNC ligands are
coordinated terminally to the Pt atoms bridged by the PPh2 ligand. The P atom of the
phosphido group exhibits a short intramolecular contact to the third Pt atom of 2.954(3) Å
(2a ) or 2.933(5) Å (2b), which is significantly below the sum of the van der Waals radii of
phosphorus and platinum.
In tr od u ction
to the Pt3(µ-dppm)3 core derive from [Pt3(µ-dppm)3-
(µ -CO)]2+ and are, in part, models for heterometallic
3
An impressive chemistry derives from the Puddephatt
catalysis. Related subvalent group 10 metal clusters
based on the [Ni3(µ-dppm)3]2+ or [Pd3(µ-dppm)3]2+ core
have been reported.7,8
cluster [Pt3(µ-dppm)3(µ -CO)]2+ containing the trian-
3
gulo-[Pt3]2+ system with a formal oxidation number of
2/3.1,2 The coordinatively unsaturated cluster can mimic
some of the properties of a metal surface as chemisorp-
tion and related phenomena as well as catalytic activity.
The ability to coordinate small molecules under mild
conditions mimics the adsorption at a Pt(111) surface
at low temperatures. The cluster has been found a
useful catalyst for the water gas shift reaction. Clusters
of the M3(µ-dppm)3 type are bifunctional recognition
hosts: The Lewis acidic M3 triangle and the hydrophobic
phenyl groups encycling the M3 skeleton form a cavity
being the basis of an interesting host-guest chemis-
try.2,3 Various heteronuclear clusters in which one or
two metals (e.g. Re,4 Ru,5 Ir,6 Sn, Hg, or Au2) are bound
The three metal atoms are locked together in a
triangle by µ-dppm ligands, preventing any cluster
fragmentation. We are interested in potential new
features upon substituting one or two of the neutral
dppm ligands of the M3(µ-dppm)3 core by anionic µ-PR2
groups, indicated as follows:
† Institut fu¨r Allgemeine, Anorganische und Theoretische Chemie.
‡ Institut fu¨r Organische Chemie,
(1) Ferguson, G.; Lloyd, B. R.; Puddephatt, R. J . Organometallics
1986, 5, 344.
(2) Puddephatt, R. J .; Manojlovic-Muir, L.; Muir, K. W. Polyhedron
1990, 9, 2767 and references therein.
(3) Zhang, T.; Drouin, M.; Harvey, P. D. J . Chem. Soc., Chem.
Commun. 1996, 877.
(6) Spivak, G. J .; Yap, G. P. A.; Puddephatt, R. J . Polyhedron 1997,
16, 3861.
(4) Muir, K. W.; Manojlovic-Muir, L.; Torabi, A. A. J . Organomet.
Chem. 1997, 536-537, 319. Xiao, J .; Kristof, E.; Vittal, J . J .; Pud-
dephatt, R. J . J . Organomet. Chem. 1995, 490, 1.
(5) King, W. D.; Lukehart, C. M. Abstr. PapsAm. Chem. Soc. 1998,
215, INOR 114.
(7) Wittrig, R. E.; Ferrence, G. M.; Washington, J .; Kubiak, C. P.
Inorg. Chim. Acta 1998, 270, 111 and references therein. Breedlove,
B. K.; Kubiak, C. P. Abstr. PapsAm. Chem. Soc. 1998, 215, INOR 144.
(8) Gauthron, I.; Mugnier, Y.; Hierso, K.; Harvey, P. D. Can. J .
Chem. 1997, 75, 1182 and references therein.
10.1021/om980635v CCC: $15.00 © 1998 American Chemical Society
Publication on Web 11/20/1998

[Pt3(µ-dppm)2(µ-PPh2)L2](O3SCF3) Complexes
Organometallics, Vol. 17, No. 26, 1998 5641
(ddd, 3J (P3P4) ) 15.3, 2J (Pt1P3) ) 70, 1J (Pt2P3) ) 3004, P3),
76.2 (dd, J (Pt2P4) ) 34, P4).
In this paper we report the synthesis and character-
ization of Pt3(µ-dppm)2(µ-PPh2) type clusters.
2
[P t2(µ-d p p m )(µ-P P h 2)(CO)2](O3SCF 3) (1b). This species
was obtained by bubbling CO for 2 min at room temperature
through a solution of 1a (0.03 mmol, 38.9 mg) in CH2Cl2 (0.5
mL). Petroleum ether (bp 50-70 °C) (2 mL) was added under
an atmosphere of CO, and the white precipitate formed was
collected by filtration and washed with the petroleum ether
and dried in vacuo. Yield: 77%. Anal. Calcd for C40H32F3O5P3-
Pt2S: C, 41.25; H, 2.77. Found: C, 41.35; H, 2.69. 31P NMR
(CD2Cl2): δ 210.9 (t, 2J (PP) ) 221.7, 1J (PtP) ) 2642, PPh2),
Exp er im en ta l Section
Gen er a l In for m a tion . NMR spectra were recorded using
a Bruker AC 200 spectrometer. 1H and 13C chemical shifts are
relative to Me4Si and were determined by reference to the
residual 1H and 13C solvent peaks. 31P/195Pt chemical shifts are
reported relative to 85% H3PO4/1 M Na2PtCl6, used as an
external reference. Coupling constants are reported in hertz.
In the NMR data, the P and Pt atoms are labeled as in the
crystal structures. Infrared spectra were recorded on a Nicolet
510 FT-IR spectrometer; mass spectra, on a Finnigan MAT
95 instrument. Elemental analyses were provided by the
Institut fu¨r Physikalische Chemie der Universita¨t Wien.
Unless otherwise noted, reagents were from commercial sup-
pliers. The compounds [Pt(η2-bicyclo[2.2.1]hept-2-ene)3] and
[Pt2(µ-dppm)2Cl2] were prepared according to literature pro-
cedures.9,10 The solvents were dried using standard procedures.
All operations were carried out under standard Schlenk
conditions.
2
1
2
4.1 (d, J (PCP) ) 62.8, J (PtP) ) 2838, J (PtP) ) 43, dppm).
195Pt NMR (CD2Cl2): δ -4885 (ddd, 1J (PtPt) ) 1803). IR
(Nujol; cm-1): ν(CO) 2072 w, 2057 s.
[P t2(µ-d p p m )(µ-P P h 2)(t-Bu NC)2](O3SCF 3) (1c). To a so-
lution of 1a (0.1 mmol, 130 mg) in CH2Cl2 (0.8 mL) was added
t-BuNC (23 µL, 0.2 mmol). The reaction mixture was stirred
for 15 min, and the solvent and bicyclo[2.2.1]hept-2-ene were
removed in vacuo, affording a red air-stable powder. Yield:
98%. Anal. Calcd for C48H50F3N2O3P3Pt2S: C, 45.21; H, 3.95;
N, 2.19. Found: C, 45.43; H, 3.86; N, 2.11. 31P NMR (CD2Cl2):
δ 193.4 (t, 2J (PP) ) 259.4, 1J (PtP) ) 2824, PPh2), 4.1 (d,
[P t 2(µ-d p p m )(µ-P P h 2)(η2-b icyclo[2.2.1]h ep t -2-en e)2]-
(O3SCF 3) (1a ). To a solution of [Pt2(µ-dppm)2Cl2] (1.00 mmol,
1.27 g) and bicyclo[2.2.1]hept-2-ene (0.94 g, 10 mmol) in CH2-
Cl2 (70 mL) was added a solution of AgO3SCF3 (0.51 g, 2.00
mmol) in MeOH (10 mL). The solution was stirred for 2 days
at 40 °C and then filtered, and the solvent was removed by
evaporation under reduced pressure. The solid residue was
washed with cold MeOH and dried under vacuum. Recrystal-
lization from MeOH gave pale yellow crystals of 1a . Yield: 70%.
Anal. Calcd for C52H52F3O3P3Pt2S: C, 48.15; H, 4.04. Found:
1
2
2J (PCP) ) 61.0, J (PtP) ) 2960, J (PtP) ) 55.7, dppm). 195Pt
NMR (CD2Cl2): δ -5038 (ddd, 1J (PtPt) ) 1552). IR (Nujol;
cm-1): ν(NC) 2149 s.
[P t3(µ-d p p m )2(µ-P P h 2)(CO)2](O3SCF 3) (2a ). A solution of
1b (0.05 mmol, 58 mg) in CH2Cl2 (0.8 mL) was stirred with
dppm (0.05 mmol, 19.2 mg) and [Pt(η2-bicyclo[2.2.1]hept-2-
ene)3] (0.05 mmol, 23.9 mg) under 1 atm of CO for 15 min.
The solvent and bicyclo[2.2.1]hept-2-ene were removed, af-
fording a yellow air-stable powder. Recrystallization from CH2-
Cl2/ethyl acetate gave yellow crystals of 2a . Yield: 63%. Anal.
Calcd for C65H54F3O5P5Pt3S: C, 44.76; H, 3.12. Found: C,
44.39; H, 2.93. 31P NMR (CD2Cl2): δ 61.1 (2J (P1P2) ) 282.5,
1
C, 48.58; H, 4.01. H NMR (CD2Cl2): bicyclo[2.2.1]hept-2-ene
δ 3.43 (m, 4H, 2J (PtH) ) 56.8, HCdCH), 1.86 (m, 4H, CH),
1.00 (m, 8H, CH2), -0.04 (m, 4H, CH2 bridge). 13C NMR (CD2-
Cl2): bicyclo[2.2.1]hept-2-ene δ 79.5 (1J (PtC) ) 145, 2J (PtC)
) 24, CdC), 43.1 (3J (PtC) ) 13, CH2 bridge), 41.4 (2J (PtC) )
37, CH), 27.4 (3J (PtC) ) 38.8, CH2); dppm δ 61.2 (t, 2J (PtC) )
2
1
3J (P1P4) ) 2.4, J (Pt1P1) ) 297, J (Pt2P1) ) 2211, P1), 13.1
(2J (P2P3) ) -6.82, 3J (P2P4) ) 106.1, 3J (P2P5) ) -0.3,
2J (Pt1P2) ) ca. 0, 1J (Pt2P2) ) 2674, 3J (Pt3P2) ) 144, P2),
17.9 (2J (P4P5) ) -8.35,1J (Pt1P4) ) 2716, J (Pt2P4) ) ca. 0,
2
106.3, J (PC) ) 27.4, PCH2P). 31P NMR (CD2Cl2): δ 229.0 (t,
1
2J (Pt3P4) ) 562, P4). 195Pt NMR (CD2Cl2): δ -4995 (1J (Pt1Pt2)
2J (PP) ) 184.9, 1J (PtP) ) 2617, PPh2), 0.8 (d, 2J (PCP) ) 55.7,
1J (PtP) ) 3001, 2J (PtP) ) 54.9, dppm). 195Pt NMR (CD2Cl2):
) 789, Pt1), -4658 (Pt2). MS (FAB; m/z): 1687.8 (M+trif-
-
2CO), 1538.2 (M+ - 2CO). IR (Nujol; cm-1): ν(CO) 2041 s, 2020
1
δ -5786 (ddd, J (PtPt) ) 2133). MS (FAB, positive ions; m/z)
1147.3 (M+), 1053.2 (M+ - C7H10), 959.1 (M+ - 2C7H10).
The methoxyphosphonium salt [P MeP h 2(OMe)](O3SCF 3)
vs.
[P t3(µ-d p p m )2(µ-P P h 2)(t-Bu NC)2](O3SCF 3) (2b). A solu-
tion of 1c (0.05 mmol, 64 mg) in CH2Cl2 (0.8 mL), dppm (0.05
mmol, 19.2 mg), and [Pt(η2-bicyclo[2.2.1]hept-2-ene)3] (0.05
mmol, 23.9 mg) was stirred for 5 min. The solvent and bicyclo-
[2.2.1]hept-2-ene were removed in vacuo, affording a yellow
air-stable powder. Recrystallization from CH2Cl2 gave 2b as
yellow crystals. Yield: 76%. Anal. Calcd for C73H72F3N2O3P5-
Pt3S: C, 47.28; H, 3.91; N, 1.51. Found: C, 46.88; H, 3.88; N,
1
was present in the MeOH fraction. H NMR (CD2Cl2): δ 7.8
(m, 10H, Ph), 4.0 (d, 3J (PH) ) 12.2, 3H, OCH3), 2.8 (d, 2J (PH)
) 13.4, 3H, CH3). 13C NMR (CD2Cl2): δ 57.8 (dq, 1J (CH) )
2
1
1
151.7, J (PC) ) 7.4, OCH3), 10.4 (dq, J (CH) ) 133.2, J (PC)
) 66.6, CH3). 31P NMR (CD2Cl2): δ 74.5. The H and 31P NMR
1
data are in good agreement with those reported in the
literature.11
[P t2(µ-dppm )(µ-P P h 2)(σ-CH2P P h 2(OMe))(η2-bicyclo[2.2.1]-
h ep t-2-en e)](O3SCF 3) (1d ). 31P NMR (CH2Cl2/MeOH, 1/1): δ
3
1.46. 31P NMR (CD2Cl2): δ 62.5 (2J (P1P2) ) 319.0, J (P1P4)
) -1.73, 2J (Pt1P1) ) 372, 1J (Pt2P1) ) 2226, P1), 13.6
(2J (P2P3) ) -7.90, 3J (P2P4) ) 117.1, 3J (P2P5) ) -3.59,
2J (Pt1P2) ) ca. 0, 1J (Pt2P2) ) 2698, 3J (Pt3P2) ) 128, P2),
1
2
16.0 (2J (P4P5) ) -5.86, J (Pt1P4) ) 2601, J (Pt2P4) ) ca. 0,
2J (Pt3P4) ) 588, P4). 195Pt NMR (CD2Cl2): δ -5050 (1J (Pt1Pt2)
) 891, Pt1), -4832 (Pt2). MS (FAB, positive ions; m/z): 1704.3
(M+). IR (Nujol; cm-1): ν(NC) 2167 s, 2136 vs.
X-r a y Str u ctu r e Deter m in a tion s. Crystals of compounds
1a , 2a , and 2b were examined by similar procedures. Crystals
were mounted on a glass fiber, and X-ray data were collected
on
a Siemens P4 diffractometer using Mo KR radiation
186.5 (ddd, 2J (P1P2) ) 171.3, 2J (P1P3) ) 313.6, 3J (P1P4) )
4.6, 1J (Pt1P1) ) 2393, 1J (Pt2P1) ) 3352, P1), -2.6 (dd,
(monochromator: highly oriented graphite crystal, ω-scan).
Unit cell parameters were determined and refined from 30-
41 randomly selected reflections in the θ range 5.3-12.5°,
obtained by the P4 automatic routine. Every 97 reflections, 3
standard reflections were measured. Data were corrected for
Lorentz-polarization and absorption effects (ψ-scans). The
structures were solved by direct methods and subsequent
1
2
2J (P2P3) ) 53.5, J (Pt1P2) ) 3053, J (Pt2P2) ) 90, P2), 9.33
(9) Crascall, L. E.; Spencer, J . L. Inorg. Synth. 1990, 28, 126.
(10) Grossel, M. C.; Batson, J . R.; Moulding, R. P.; Seddon, K. R. J .
Organomet. Chem. 1986, 304, 391.
(11) Colle, K. S.; Lewis, E. S. J . Org. Chem. 1978, 43, 571.

5642 Organometallics, Vol. 17, No. 26, 1998
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
Wachtler et al.
1a ‚2MeOH
2a ‚3CH2Cl2
2b
empirical formula
fw
C
52H52F3O3P3Pt2S‚2MeOH
C65H53F3O5P5Pt3S‚3CH2Cl2
1998.03
C73H72F3N2O3P5Pt3S
1854.51
1361.17
crystal system
space group
unit cell dimens
orthorhombic
P212121 (No. 19)
monoclinic
P21/n (No. 14)
monoclinic
P21/n (No. 14)
a ) 13.514(3) Å, b ) 18.532(2) Å, a ) 11.592(4) Å, b ) 26.965(2) Å, a ) 15.601(6) Å, b ) 26.597(5) Å,
c ) 20.942(4) Å; R ) 90°,
â ) 90°, γ ) 90°
5.245(2)
c ) 22.816(2) Å, R ) 90°,
â ) 91.26(2)°, γ ) 90°
7.130 (3)
c ) 17.071(4) Å, R ) 90°,
â ) 90.31(3)°, γ ) 90°
7.083 (4)
vol, nm3
Z
4
4
4
density (calcd), Mg/m3
temp, K
1.724
213(2)
5.517
1.861
213(2)
6.294
yellow prism
0.8 × 0.18 × 0.18 mm
2.59-21.75
0 e h e 11, 0 e k e 28,
-23 e l e 23
8890
8387 (Rint ) 0.0290)
6578
0.953 and 0.846
7862/0/820
1.037
1.739
218(2)
6.108
yellow prism
0.4 × 0.25 × 0.15 mm
2.51-20.35
0 e h e 15, -1 e k e 26,
-17 e l e 17
7639
6913 (Rint ) 0.0529)
4946
0.904 and 0.565
6324/7/812
1.033
abs coeff, mm-1
color, habit
crystal size, mm
θ range for data collcn, deg
index ranges
light yellow prism
0.45 × 0.45 × 0.4 mm
2.67-23.50
-5 e h e 15, -1 e k e 21,
-1 e l e 23
6495
5727 (Rint ) 0.0168)
5166
0.838 and 0.677
5609/4/648
1.050
no. of reflcns collected
no. of indep reflcns
no. of reflcns with I > 2σ(I)
max and min transm
data/restraints/parameters
goodness-of-fit on F2
final R indices [I > 2σ(I)]
R1 ) 0.0285, wR2 ) 0.0565
R1 ) 0.0360, wR2 ) 0.0757
R1 ) 0.0501, wR2 ) 0.1055
R indices (all data)
R1 ) 0.0368, wR2 ) 0.0593
R1 ) 0.0576, wR2 ) 0.0850
R1 ) 0.0869, wR2 ) 0.1246
absolute structure parameter -0.014(8)
largest diff peak and hole,
694 and -568
1421 and -816
1188 and -1253
e nm-3
scan speed, deg/min in ω
scan range (ω), deg
weighting scheme
4.0
0.75
5.0
0.7
5.0
0.65
calc w ) 1/[σ2(Fo2) +
(0.0318P)2 + 4.3664P]
calc w ) 1/[σ2(Fo2) +
(0.0417P)2 + 29.6800P]
calc w ) 1/[σ2(Fo2) +
(0.0594P)2 + 37.5663P]
where P ) (Fo + 2Fc2)/3
where P ) (Fo + 2Fc2)/3
where P ) (Fo + 2Fc2)/3
2
2
2
difference Fourier techniques (SHELXS-86).12 Refinement on
F2 with all measured reflections was carried out by full-matrix
least-squares techniques (SHELXL-93).13
and 2b (32 pages). Ordering information is given on any
current masthead page.
Pale yellow crystals of [Pt2(µ-dppm)(µ-PPh2)(η2-bicyclo[2.2.1]-
hept-2-ene)2](O3SCF3)‚2MeOH were obtained by slowly cooling
a boiling methanolic solution of 1a to room temperature. All
non-hydrogen atoms were refined anisotropically. The hydro-
gen atoms at C1, C2, C8, and C9 were refined isotropically
with a fixed distance of 0.95 Å to the C atoms. All other
hydrogen atoms were placed at calculated ideal positions
(riding model). Hydrogen atoms at the MeOH molecules were
omitted. One of the solvent molecules was found to be
disordered and was refined in two positions with 0.5 oc-
cupancy.
Yellow crystals of [Pt3(µ-dppm)2(µ-PPh2)(CO)2](O3SCF3)‚3CH2-
Cl2 were grown by slow diffusion of ethyl acetate into a solution
of 2a in CH2Cl2. All non-hydrogen atoms were refined aniso-
tropically. Hydrogen atoms were placed at calculated ideal
positions (riding model).
Resu lts a n d Discu ssion
[P t2(µ-d p p m )(µ-P P h 2)L2](O3SCF 3) (L ) Bicyclo-
[2.2.1]h ep t-2-en e (1a ), CO (1b), t-Bu NC (1c)). The
reaction of [Pt2(µ-dppm)2Cl2] with 2 mequiv of AgO3-
SCF3 and bicyclo[2.2.1]hept-2-ene, respectively, in CH2-
Cl2/MeOH gives [Pt2(µ-dppm)(µ-PPh2)(η2-bicyclo[2.2.1]-
hept-2-ene)2](O3SCF3) (1a) and the methoxyphosphonium
salt [PMePh2(OMe)](O3SCF3)11 according to Scheme 1.
This reaction involves the fission of the bond between
the aliphatic carbon and one phosphorus atom of one
dppm ligand. The cleavage of P-C bonds of dppm in
the coordination sphere of various metals has been
previously observed: in one type, a metal-mediated
oxidative P-C bond cleavage gives PPh2 and CH2PPh2
fragments. Either both P groups or only the PPh2 group
is retained in the coordination sphere of the metal.14-18
Yellow crystals of [Pt3(µ-dppm)2(µ-PPh2)(t-BuNC)2](O3SCF3)
were grown by slow evaporation of a solution of 2b in CH2Cl2.
All non-hydrogen atoms of the [Pt3(µ-dppm)2(µ-PPh2)(t-BuNC)2]+
cation were refined anisotropically. Hydrogen atoms were
-
(14) 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.
(15) Riera, V.; Ruiz, M. A.; Villafane, F.; Bois, C.; J eannin, Y. J .
Organomet. Chem. 1989, 375, C23.
(16) Elliot, D. J .; Holah, D. G.; Hughes, A. N.; Mirza, H. A.; Zawanda,
E. J . Chem. Soc., Chem. Commun. 1990, 32. Hanson, B. E.; Fanwick,
P. E.; Mancini, J . S. Inorg. Chem. 1982, 21, 3811.
(17) Doherty, N. M.; Hogarth, G.; Knox, S. A. R.; Macpherson, K.
A.; Melchior, F.; Morton, D. A. V.; Orpen, A. G. Inorg. Chim. Acta 1992,
198-200, 257. Doherty, N. M.; Hogarth, G.; Knox, S. A. R.; Macpher-
son, K. A.; Melchior, F. M.; Orpen, A. G. J . Chem. Soc., Chem. Commun.
1986, 540. Grist, N. J .; Hogarth, G.; Knox, S. A. R.; Lloyd, B. R.;
Morton, D. A. V.; Orpen, A. G. J . Chem. Soc., Chem. Commun. 1988,
673.
placed at calculated ideal positions (riding model). The O3SCF3
anion was found to be disordered in two positions: one lies
nearby an inversion center with S1 ) C11, F1 ) O1, F2 ) O2,
and F3 ) O3; the other has an occupancy of 0.5 at a common
position. Only S2 could be refined anisotropically.
Crystal data and details of the structure determinations and
refinements are collected in Table 1.
Listings of positional and thermal parameters, complete
bond distances and angles, anisotropic thermal parameters,
and hydrogen atom coordinates for 1a ‚2MeOH, 2a ‚3CH2Cl2,
(12) Sheldrick, G. M. SHELXS-86: program for crystal structure
solutions. University of Go¨ttingen, 1986.
(13) Sheldrick, G. M. SHELXL-93: program for refinement of crystal
structures. University of Go¨ttingen, 1993.
(18) Lavigne, G.; Bonnet, J .-J . Inorg. Chem. 1981, 20, 2713. Lugan,
N.; Bonnet, J .-J .; Ibers, J . A. J . Am. Chem. Soc. 1985, 107, 4484.
Bergounhou, C.; Bonnet, J .-J .; Fompeyrine, P.; Lavigne, G.; Lugan,
N.; Mansilla, F. Organometallics 1986, 5, 60.

[Pt3(µ-dppm)2(µ-PPh2)L2](O3SCF3) Complexes
Organometallics, Vol. 17, No. 26, 1998 5643
Sch em e 1
A second type, formally a hydrolysis of dppm, involves
a nucleophilic attack by hydroxide ions at one phospho-
rus atom to produce Ph2P(O)H and MePh2P.19
The reaction sketched in Scheme 1 does not occur in
the absence of bicyclo[2.2.1]hept-2-ene. This may be in
keeping with recent evidence indicating that the P-C
cleavage in a Ru complex is more sensitive to an
electronic supersaturation than to a transient unsat-
uration.14
Figu r e 1. Molecular structure of 1a. The trifluoromethane-
sulfonate anion and phenyl groups are omitted for clarity.
No platinum intermediate carrying a CH2PPh2 ligand
was detected when the present reaction was monitored
by 31P NMR. In the presence of the base CaCO3
however, [Pt2(µ-dppm)(µ-PPh2)(σ-CH2PPh2(OMe))(η2-
bicyclo[2.2.1]hept-2-ene)](O3SCF3) (1d ) was identified as
an intermediate by 31P NMR spectroscopy (see Experi-
mental Section), indicating a possible mechanism: The
fission of the P-C bond results in [Pt2(µ-dppm)(µ-
P P h 2)(CH 2P P h 2)(η2-bicyclo[2.2.1]h ept -2-en e)](O3S-
CF3)2. A nucleophilic attack by methanol at the phos-
phorus atom of the CH2PPh2 group gives 1d and 1
mequiv of trifluoromethanesulfonic acid. In the absence
of CaCO3, the products 1a and [PMePh2(OMe)](O3SCF3)
are finally formed via acidolysis of the Pt-C σ-bond by
HO3SCF3 and subsequent coordination of bicyclo[2.2.1]-
hept-2-ene.
Ta ble 2. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for Com p lex 1a
Pt(1)-Pt(2)
Pt(1)-P(1)
Pt(1)-P2)
Pt(2)-P(1)
Pt(2)-P(3)
2.7047(6)
2.236(2)
2.299(2)
2.232(2)
2.291(2)
Pt(1)-C(1)
Pt(1)-C(2)
Pt(2)-C(8)
Pt(2)-C(9)
C(1)-C(2)
C(8)-C(9)
2.181(9)
2.203(10)
2.204(9)
2.193(8)
1.409(14)
1.386(12)
P(2)-Pt(1)-Pt(2)
P(2)-Pt(1)-P(1)
Pt(2)-Pt(1)-P(1)
P(3)-Pt(2)-Pt(1)
P(3)-Pt(2)-P(1)
Pt(1)-Pt(2)-P(1)
C(8)-Pt(2)-P(1)
C(9)-Pt(2)-P(3)
91.57(6) Pt(1)-P(1)-Pt(2)
74.52(7)
143.96(9) C(23)-P(2)-Pt(1) 112.4(3)
52.68(6) C(23)-P(3)-Pt(2) 113.8(3)
94.74(7) P(2)-C(23)-P(3)
147.06(9) C(1)-Pt(1)-P(1)
52.80(6) C(2)-Pt(1)-P(2)
110.0(5)
87.4(3)
91.2(3)
37.5(4)
36.8(3)
91.3(2)
85.4(2)
C(1)-Pt(1)-C(2)
C(8)-Pt(2)-C(9)
In this context, it is interesting to note, that the side-
on-coordinated CH2PPh2 ligand in [Ru2(CO)2(PR3)(η2-
CH2PPh2)(µ-O2CMe)(µ-dppm)(µ-PPh2)]+, which was also
generated via a CH2-P cleavage of dppm, was extruded
by the nucleophilic attack of PR3 at the carbon site to
give [PPh2CH2PR3]+ whereas the nucleophile MeOH
attacks at the P atom in the present reaction.14
The [Pt2(µ-dppm)(µ-PPh2)] framework was previously
described in the complex [Pt2(µ-dppm)(µ-PPh2)(PPh3)2]+,
which was obtained by fragmentation of the trinuclear
clusters [Pt3(µ-PPh2)2(PPh3)3X]+ (X ) Cl, H, PR2, SR)
with dppm.20
As indicated in Scheme 1, the bicyclo[2.2.1]hept-2-ene
ligands of 1a are readily substituted by CO or t-BuNC
to give 1b and 1c.
A X-ray crystallographic study of 1a was undertaken.
A drawing of the cation of 1a is shown in Figure 1.
Selected bond distances and angles are listed in Table
2.
Crystals of 1a contain one trifluoromethanesulfonate
anion and two methanol molecules for each [Pt2(µ-
dppm)(µ-PPh2)(bicyclo[2.2.1]hept-2-ene)2]+ cation. The
anion and the methanol molecules show no unusual
structural features and will not be considered further
here.
The orientation of the CdC double bonds is nearly
coplanar with the other ligands coordinated to the Pt
atoms: the deviations of the π-bonded carbon atoms
from the least-squares planes spanned by the platinum
atoms and the corresponding two cis phosphorus atoms
amount to 0.04(1) and -0.27(1) Å for C1 and C2 and
-0.41(1) and -0.14(1) Å for C8 and C9. An approxi-
mately “in-plane” geometry for olefin ligands is char-
acteristic for three-coordinated Pt(0) complexes.21 In
Pt(II) complexes, alkenes are usually coordinated “up-
(19) Bergamini, P.; Sostero, S.; Traverso, O.; Kemp, T. J .; Pringle,
P. G. J . Chem. Soc., Dalton Trans. 1989, 2017. Alcock, N. W.;
Bergamini, P.; Kemp, T. J .; Pringle, P. G. J . Chem. Soc., Chem.
Commun. 1987, 235. Lin, I. J . B.; Lai, J . S.; Liu, C. W. Organometallics
1990, 9, 530.
(20) Hadj-Bagheri, N.; Browning, J .; Dehghan, K.; Dixon, K. R.;
Meanwell, N. J .; Vefghi, R. J . Organomet. Chem. 1990, 396, C47.
(21) Hartley, F. R. In Comprehensive Organometallic Chemistry;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: Oxford,
U.K., 1982; Vol. 6, Chapter 39. Young. G. B. In Comprehensive
Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson,
G., Eds.; Pergamon: Oxford, U.K., 1995; Vol. 9, Chapter 9.

5644 Organometallics, Vol. 17, No. 26, 1998
Wachtler et al.
right” to the metal atom, with the CdC double bond
perpendicular to the platinum coordination plane,21 but
there also exist a few examples of “in-plane” and
intermediate orientation, which were attributed to the
geometry and steric demands of the olefins.22 The “in-
plane” coordination geometry of the alkenes in 1a may
be favored by the ample P1-Pt1-P2/P1-Pt2-P3 angles
of ca. 214.5° (average) within the Pt2(µ-dppm)(µ-PPh2)
framework. A search in the Cambridge Structural
Database for Pt(I)-olefin complexes gave [Pt2(µ-(CF3)2-
CO))(η4-cycloocta-1,5-diene)2] as the sole structurally
characterized example. All CdC double bonds are
oriented “upright” in this complex.23
Figu r e 2. Molecular structure of 2a. The trifluoromethane-
sulfonate anion and phenyl groups are omitted for clarity.
The CdC double bonds of the bicyclo[2.2.1]hept-2-ene
ligands show a lengthening to 1.40 Å (average); the Pt-
C(π) bond lengths with a mean distance of 2.20 Å
correspond to those found for other platinum π-olefin
complexes.24 Both of the bridging methylene groups of
the bicyclo[2.2.1]hept-2-ene ligands are on the same side
of the platinum coordination plane. The bicyclo[2.2.1]-
hept-2-ene molecules are positioned directly in the
middle between the cis-phosphorus atoms with an angle
X-Pt-P of 107° (average; X ) midpoint of the CdC
double bond).
In the [Pt2(µ-dppm)(µ-PPh2)(bicyclo[2.2.1]hept-2-ene)2]+
cation, the Pt1-Pt2 distance (2.7047(6) Å) lies in the
range of Pt-Pt bond lengths found for diplatinum(I)
complexes25 and is very similar to the Pd-Pd separation
(2.688(2) Å) in the related Pd(I) complex [Pd2(µ-i-Pr2-
PCH2PPh2)(µ-PPh2)(PPh3)2]+.20 The five-membered ring
formed by the two Pt atoms and the dppm ligand adopts
an envelope conformation with the methylene carbon
at the flap.
The 31P{1H} NMR spectra of 1a -c recorded at ambi-
ent temperature in CD2Cl2 show the pattern of an A2X
spin system and are flanked by satellites due to coupling
with 195Pt nuclei. The chemical shifts and coupling
constants of 1a -c are similar to the values reported for
[Pt2(µ-dppm)(µ-PPh2)(PPh3)2]+.20 The chemical shift of
P1 increases and the value of 1J (PtP1) decreases in the
order PPh3 ≈ t-BuNC/CO/bicyclo[2.2.1]hept-2-ene. The
195Pt{1H} NMR spectra of 1a -c exhibit resonances at
-5786 ppm (1a ), -4885 ppm (1b), and -5038 ppm (1c).
There is a remarkably large difference between the
shifts of 1a and 1b, which is however difficult to
evaluate in view of a lack of comparable data. The
195Pt{1H} NMR spectra of 1a -c also reveal the pattern
of the isotopomers containing two 195Pt nuclei, from
which the 1J (PtPt) couplings are extracted, which
decrease in the order PPh3 > t-BuNC > CO > bicyclo-
[2.2.1]hept-2-ene.
Figu r e 3. Molecular structure of 2b. The trifluoromethane-
sulfonate anion and phenyl groups are omitted for clarity.
interatomic distances and angles are collected in Table
3.
The cluster skeleton of 2a and 2b consists of a Pt3
triangle with the edges spanned by two bridging dppm
ligands and one bridging phosphido group. The dppm-
bridged platinum atoms involve short Pt-Pt distances
(2.6456(8) and 2.6733(6) Å for 2a and 2.6463(11) and
2.6534(12) Å for 2b) whereas a long Pt-Pt separation
is observed between the phosphido-bridged Pt atoms
(2a , 3.5949(6) Å; 2b, 3.470(1) Å). The carbonyl ligands
are η1-coordinated to the terminal Pt atoms of the bent
Pt3 chain with a Pt-C-O angle of 173.7° (average), a
mean Pt-C distance of 1.90 Å, and a C-O bond length
of 1.13 Å (average). The terminal isonitrile ligands in
2b exhibit approximately linear geometries (mean Pt-
C-N angle 174.5°; mean C-N-C angle 176°), the Pt-C
distance is 1.96 Å (average), and the C-N bond length
is 1.15 Å (average). Each of the three Pt atoms in 2a
and 2b shows an approximately square planar coordi-
nation geometry as indicated in Figures 2 and 3. The
least-squares planes through Pt2 and Pt3 are twisted
by 37.7° (average) with respect to the least-squares
plane through Pt1 in 2a (2b: 39.7°, average). Due to
the folding of the Pt coordination planes, the P atom of
the phosphido bridge adopts a position with a short
contact to Pt1 (2a , 2.954(3) Å; 2b, 2.933(5) Å) which is
distinctly less than the van der Waals estimate of 3.6
Å. There are examples for µ2-phosphido groups with a
short contact to a third metal atom known in the
literature. The M-P distances range from 3.002 Å,
attributable to weak electronic interaction, to 2.466 Å,
representing a triply bridging phosphido group.26,27 The
[P t3(µ-d p p m )2(µ-P P h 2)L2](O3SCF 3) (L) CO (2a ),
t-Bu NC (2b )). Upon treatment of 1b with the zero-
valent platinum complex [Pt(η2-bicyclo[2.2.1]hept-2-
ene)3] and dppm, the cationic trinuclear cluster 2a is
formed according to Scheme 1. Similarly, the related
cluster 2b is obtained from 1c. The solid-state structures
of 2a and 2b are shown in Figures 2 and 3, and selected
(22) Miki, K.; Yamatoya, K.; Kasai, N.; Kurosawa, H.; Urabe, A.;
Emoto, M.; Tatsumi, K.; Nakamura, A. J . Am. Chem. Soc. 1988, 110,
3191 and references therein.
(23) Green, M.; Howard, J . A. K.; Laguna, A.; Smart, L. E.; Spencer,
J . L.; Stone, F. G. A. J . Chem. Soc., Dalton Trans. 1977, 278.
(24) Ibers, J . A.; Ittel, S. D. Adv. Organomet. Chem. 1976, 14, 33.
(25) Anderson, G. K. Adv. Organomet. Chem. 1993, 35, 1.
(26) Hartung, H.; Walther, B.; Baumeister, U.; Bo¨ttcher, H.-C.;
Krug, A.; Rosche, F.; J ones, P. G. Polyhedron 1992, 11, 1563. Brauer,
D. J .; Hessler, G.; Knu¨ppel, P. C.; Stelzer, O. Inorg. Chem. 1990, 29,
2370. MacLaughlin, S. A.; Carty, A. J .; Taylor, N. J . Can. J . Chem.
1982, 60, 87. Bender, R.; Braunstein, P.; Dedieu, A.; Dusausoy, Y.
Angew. Chem., Int. Ed. Engl. 1989, 28, 923. Eichho¨fer, A.; Fenske, D.;
Holstein, W. Angew. Chem., Int. Ed. Engl. 1993, 32, 242.

[Pt3(µ-dppm)2(µ-PPh2)L2](O3SCF3) Complexes
Organometallics, Vol. 17, No. 26, 1998 5645
F igu r e 4. Experimental 31P{1H} NMR spectrum of 2b (upper trace) and simulated spectrum (lower trace, isotopomer
without 195Pt nuclei). Additional peaks in the experimental spectrum with respect to the simulated spectrum result from
the isotopomers containing 195Pt nuclei; especially in the dppm region, the signals are overlapping with the platinum
satellites, which are broadend by chemical shift anisotropy and probably by scalar relaxation of the second kind (coupling
of 195Pt with 14N of the isonitriles).
Ta ble 3. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for Com p lexes 2a a n d 2b
In contrast to those of other dppm-bridged triplatinum
complexes,2 the Pt2PCP rings in 2a and 2b do not show
envelope conformations but are twisted.
2a
2b
Clusters 2a and 2b are based on the [Pt3]2+ or
Pt(1)-Pt(2)
Pt(1)-Pt(3)
Pt(1)-P(4)
Pt(1)-P(5)
Pt(2)-P(1)
Pt(2)-P(2)
Pt(3)-P(1)
Pt(3)-P(3)
Pt(2)-C(1)
Pt(3)-C(2)
O(1)-C(1)
O(2)-C(2)
2.6733 (6) Pt(1)-Pt(2)
2.6456 (8) Pt(1)-Pt(3)
2.6463 (11)
2.6534 (12)
2.263 (5)
2.261 (5)
2.275 (4)
2.279 (4)
2.294 (5)
2.310 (5)
1.97 (2)
PtI Pt0 system involving the formal oxidation number
2
2
of
/
like the Puddephatt cluster [Pt3(µ-dppm)3-
3
2.289 (3)
2.275 (3)
2.285 (3)
2.321 (3)
2.276 (2)
2.284 (2)
Pt(1)-P(4)
Pt(1)-P(5)
Pt(2)-P(1)
Pt(2)-P(2)
Pt(3)-P(1)
Pt(3)-P(3)
(µ -CO)]2+ and various derivatives.2 The formal sub-
3
stitution of one dppm ligand in the Pt3(µ-dppm)3 frame-
work of [Pt3(µ-dppm)3(µ3-CO)]2+ by a PPh2 group has
interesting implications: First, there are only two
Pt-Pt bonds in the Pt3 system of 2a , whereas the
platinum atoms in [Pt3(µ-dppm)3(µ3-CO)]2+ are arranged
in the form of an almost equilateral triangle (Pt-Pt
distances 2.613-2.650 Å).1 Second, two η1-CO ligands
are coordinated to the Pt atoms in 2a , making an
electron count of 44, whereas the Puddephatt cluster
contains one µ3-CO and thus has 42 electrons.
1.913 (12) Pt(2)-C(1)
1.893 (12) Pt(3)-C(6)
1.124 (12) N(1)-C(1)
1.132 (13) N(2)-C(6)
1.94 (2)
1.15 (2)
1.14 (2)
Pt(3)-Pt(1)-Pt(2) 85.04 (2)
Pt(3)-Pt(1)-Pt(2) 81.80 (4)
Pt(2)-Pt(1)-P(4) 90.47 (12)
102.06 (9) P(4)-Pt(1)-P(5) 103.4 (2)
Pt(2)-Pt(1)-P(4) 83.87 (7)
P(4)-Pt(1)-P(5)
P(5)-Pt(1)-Pt(3) 89.01 (7)
P(5)-Pt(1)-Pt(3) 84.13 (12)
Other examples involving the [Pt3]2+ core comprise
[Pt3(2,6-Me2C6H3NC)8](PF6)2 (44 e),29 [Pt3(2,6-Me2C6H3-
NC)6(PPh3)2](PF6)2,29,30 and [Pt3(2,6-Me2C6H3NC)4(η2-
dppen)2](PF6)2 (dppen ) cis-1,2-bis(diphenylphosphino)-
ethene) (44 e),31 which all adopt a linear Pt3 chain. The
A-frame type cluster [Pt3(2,6-Me2C6H3NC)4(µ-dppm)2]-
(PF6)2 (44 e) involves a bent triplatinum chain with an
average Pt-Pt bond length of 2.593 Å and a nonbonded
Pt-Pt distance of 3.304(2) Å.29,32 The two dppm ligands
doubly bridge the nonbonded platinum atoms, and this
represents an arrangement of the Pt3(µ-dppm)2 frag-
ment which is isomeric with that of 2a and 2b. The 42
e cluster Pt3(µ-Ph)(µ-SO2)(µ-PPh2)(PPh3)3 exhibits a
triangular Pt skeleton (Pt-Pt 2.8155(10), 2.6958(12),
2.7810(14) Å).33
P(4)-Pt(1)-Pt(3) 168.87 (6) P(4)-Pt(1)-Pt(3) 169.91 (12)
P(5)-Pt(1)-Pt(2) 174.02 (7) P(5)-Pt(1)-Pt(2) 165.92 (12)
P(1)-Pt(2)-C(1)
C(1)-Pt(2)-P(2)
98.4 (3)
98.9 (3)
P(1)-Pt(2)-C(1)
C(1)-Pt(2)-P(2)
96.7 (5)
102.2 (5)
P(2)-Pt(2)-Pt(1) 90.79 (6)
P(2)-Pt(2)-Pt(1) 88.59 (11)
Pt(1)-Pt(2)-P(1) 72.71 (12)
161.98 (9) P(2)-Pt(2)-P(1) 160.7 (2)
Pt(1)-Pt(2)-P(1) 72.65 (6)
P(2)-Pt(2)-P(1)
C(1)-Pt(2)-Pt(1) 168.3 (4)
C(1)-Pt(2)-Pt(1) 169.2 (5)
P(3)-Pt(3)-C(2)
C(2)-Pt(3)-P(1)
99.4 (3)
99.6 (3)
P(3)-Pt(3)-C(6)
C(6)-Pt(3)-P(1)
93.1 (6)
104.3 (6)
P(1)-Pt(3)-Pt(1) 73.33 (6)
P(1)-Pt(3)-Pt(1) 72.31 (11)
Pt(1)-Pt(3)-P(3) 90.17 (12)
160.45 (9) P(3)-Pt(3)-P(1) 162.0 (2)
Pt(1)-Pt(3)-P(3) 88.16 (7)
P(3)-Pt(3)-P(1)
C(2)-Pt(3)-Pt(1) 171.0 (4)
Pt(3)-P(1)-Pt(2) 104.04 (9) Pt(3)-P(1)-Pt(2) 98.8 (2)
C(6)-Pt(3)-Pt(1) 176.4 (6)
Pt(2)-P(2)-C(24) 113.0 (3)
C(35)-P(3)-Pt(3) 106.8 (3)
C(24)-P(4)-Pt(1) 107.9 (3)
Pt(1)-P(5)-C(35) 115.2 (3)
Pt(2)-P(2)-C(24) 110.7 (6)
C(35)-P(3)-Pt(3) 112.8 (6)
C(24)-P(4)-Pt(1) 115.8 (6)
Pt(1)-P(5)-C(35) 105.5 (5)
172.5 (11) N(1)-C(1)-Pt(2) 176 (2)
There also exist clusters involving a [Pt3]4+ or
O(1)-C(1)-Pt(2)
O(2)-C(2)-Pt(3)
P(2)-C(24)-P(4)
P(5)-C(35)-P(3)
174.9 (12) N(2)-C(6)-Pt(3)
173 (2)
(28) Hambley, T. W. Inorg. Chem. 1998, 37, 3767.
(29) Yamamoto, Y.; Takahashi, K.; Yamazaki, H. J . Am. Chem. Soc.
1986, 108, 2458. Yamamoto, Y.; Takahashi, K.; Yamazaki, H. Orga-
nometallics 1993, 12, 933.
(30) Briant, C. E.; Gilmour, D. I.; Mingos, D. M. P. J . Organomet.
Chem. 1986, 308, 381.
106.5 (5)
108.9 (5)
P(2)-C(24)-P(4)
P(5)-C(35)-P(3)
C(1)-N(1)-C(2)
C(6)-N(2)-C(7)
110.2 (9)
106.0 (8)
178 (2)
174 (2)
(31) Tanase, T.; Ukaji, H.; Kudo, Y.; Ohno, M.; Kobayashi, K.;
Yamamoto, Y. Organometallics 1994, 13, 1374.
(32) Bradford, A. M.; Payne, N. C.; Puddephatt, R. J .; Yang, D.-S.;
Marder, T. B. J . Chem. Soc., Chem. Commun. 1990, 1462.
(33) Evans, D. G.; Hughes, G. R.; Mingos, D. M. P.; Bassett, J .-M.;
Welch, A. J . J . Chem. Soc., Chem. Commun. 1980, 1255.
Pt‚‚‚P distances in 2a and 2b may be classified as van
der Waals contacts.28
(27) Alonso, E.; Fornie´s, J .; Fortun˜o, C.; Mart´ın, A.; Orpen A. G. J .
Chem. Soc., Chem. Commun. 1996, 231.

5646 Organometallics, Vol. 17, No. 26, 1998
Wachtler et al.
PtI PtII system: the 44 e cluster Pt3(µ-PPh2)3Ph(PPh3)2
exhibits an interesting skeletal isomerism and exists
Pt2 and Pt3.36 This is confirmed by the crystal structure
showing a large Pt-P-Pt angle (98.8°) and no metal-
metal bonding between Pt2 and Pt3. The signal is
flanked by two sets of Pt satellites (1J (Pt2P1) ) 2226
2
alternately in
a cyclic (Pt-Pt 2.956(3), 2.956(3),
3.074(4) Å) or open triangle form (Pt-Pt 2.758(3),
2.758(3), 3.586(2) Å) depending on the crystallization
conditions.34 Extended Hu¨ckel calculations showed that
the former isomer is slightly more stable. Other ex-
amples are the recently reported Pt3(µ-t-Bu2P)3(H)(CO)2
(44 e, with two short (2.7247(6), 2.7165(6) Å) and one
long (3.6135(6) Å) Pt-Pt distances)35 and the above-
mentioned 42-electron clusters [Pt3 (µ-PPh2)2(PPh3)3X]+
(X ) Cl, H, PR2, SR).20
2
Hz, J (Pt1P1) ) 372 Hz). The relatively large value of
2J (Pt1P1) can be explained by some through-space
coupling, if the short Pt1-P1 distance found in the
crystal structure (2.93 Å) is maintained in solution.35
The 31P chemical shifts and P-P coupling constants of
2a and 2b were obtained by computer simulation of the
experimental spectrum.37 Figure 4 shows the experi-
mental and the simulated 31P{1H} NMR spectra of 2b.
The 195Pt{1H} NMR spectrum of 2b exhibits two
resonances at -5050 (Pt1; td) and -4832 ppm (Pt2, Pt3;
dddd). Both sets of signals are flanked by satellites due
to the presence of the isotopomers 195Pt1195Pt2Pt3 and
195Pt1Pt2195Pt3 (1J (Pt1Pt2) ) 891 Hz); the subspectrum
resulting from the isotopomer Pt1195Pt2195Pt3 was not
observed.
A [Pt3]6+ system exhibiting a bent Pt3 chain arrange-
ment is present in [NBu4][Pt3(µ-PPh2)2(C6F5)5] with an
electron count of 44, which is consistent with two
Pt-Pt bonds (2.772(1) and 2.899(1) Å) between the PtII
centers.27
The NMR parameters of 2a and 2b are closely related;
therefore, only those of 2b are discussed here. The
31P{1H} NMR spectrum of 2b recorded at ambient
temperature in CD2Cl2 consists of an AA′BB′X spin
system with satellites due to the isotopomers containing
195Pt nuclei. The resonance at 62.5 ppm is assigned to
the phosphido ligand. The 31P chemical shift of bridging
phosphido groups is sensitive to the M-P-M angle, and
the value for 2b indicates the absence of a bond between
Su p p or tin g In for m a tion Ava ila ble: Listings of posi-
tional and thermal parameters, all bond distances and angles,
anisotropic thermal parameters, and hydrogen atom coordi-
nates for 1a ‚2MeOH, 2a ‚3CH2Cl2, and 2b (32 pages). Ordering
information is given on any current masthead page.
OM980635V
(34) Bender, R.; Braunstein, P.; Dedieu, A.; Ellis, P. D.; Huggins,
B.; Harvey, P. D.; Sappa, E.; Tiripicchio, A. Inorg. Chem. 1996, 35,
1223.
(35) Leoni, P.; Manetti, S.; Pasquali, M.; Albinati, A. Inorg. Chem.
1996, 35, 6045.
(36) Carty, A. J .; MacLaughlin, S. A.; Nucciarone, D. In Phosphorus-
31 NMR Spectroscopy in Stereochemical Analysis; Verkade, J . G., Quin,
L. D., Eds.; VCH Publishers: New York, 1987; Chapter 16.
(37) Program PANIC, Bruker.