Mononuclear Platinum(II) and Palladium(II) Dithiolate Complexes as Chelate Metalloligands for Preparation of Heterobimetallic d8-d8 Complexes

Article abstract of DOI:10.1021/ic970557o

Palladium - rhodium and platinum - rhodium heterobimetallic bridged dithiolate complexes of general formula [(P-P)M(μ-S-S)Rh(COD)]ClO₄ (COD = 1,5-cyclooctadiene. For M = Pt: P-P = (PPh₃)₂ and S-S = EDT^2- (1,2-ethanedithiolate) (1), PDT^2- (1,3-propanedithiolate) (2), and BDT^2- (1,4-buthanedithiolate) (3); P-P = dppb (1,4-bis(diphenylphosphino)butane) and S-S = EDT^2- (4), PDT^2- (5), and BDT^2- (6); P-P = dppp (1,3-bis-(diphenylphosphino)propane) and S-S = EDT^2- (7), PDT^2- (8), and BDT^2- (9). For M = Pd: P-P = dppb and S-S = EDT^2- (10), PDT^2- (11), and BDT^2- (12); P-P = dppp and S-S = EDT^2- (13), PDT^2- (14), and BDT^2- (15)) have been prepared. The crystal structures for complexes 1-3, 6, 9, and 12 have been determined, and hinged structures were found with angles between local coordination planes MS₂Rh ranging from 111.27° for complex 1 to 151.34° for complex 3. Metal-metal distances show nonbonding interactions between metals. X-ray data for 1: triclinic, P1?, a = 11.311(6) A?, b = 12.991(6) A?, c = 16.140(6) A?, α = 84.86(6)°, β= 75.73(6)°, γ = 86.43(6)°, Z = 2, R = 0.0427 (R_w = 0.1151). X-ray data for 2: triclinic, P1?, a = 11.084(5) A?, b = 13.094(6) A?, c = 16.338(6) A?, α = 86.06(6)°, β = 75.67(6)°, γ = 88.55(6)°, Z = 2, R = 0.0470 (R_w = 0.1264). X-ray data for 3: orthorbombic, Pbca, a = 14.439(6) A?, b = 19.807(6) A?, c = 38.156(6) A?, Z = 8, R = 0.0864 (R_w = 0.2457). X-ray data for 6: monoclinic, P2₁/c, a = 20.338(6) A?, b= 14.227(6) A, c = 14.570(6) A?, β = 100.94(6)°, Z = 4, R = 0.0536 (R_w = 0.1449). X-ray data for 9: monoclinic, P2₁/c, a = 20.326(6) A?, b = 14.109(6) A?, c = 14.368(6) A?, β = 100.90(6)°, Z = 4, R = 0.0380 (R_w = 0.0990). X-ray data for 12: monoclinic, P2₁/c, a = 20.365(6) A?, b = 14.186(6) A?, c = 14.592(6) A?, β = 101.04(6)°, Z = 4, R = 0.0507 (R_w = 0.1500).

Full text of DOI:10.1021/ic970557o

2626
Inorg. Chem. 1998, 37, 2626-2632
Mononuclear Platinum(II) and Palladium(II) Dithiolate Complexes as Chelate
Metalloligands for Preparation of Heterobimetallic d8-d8 Complexes
Jorge Fornie´s-Ca´mer,† Anna M. Masdeu-Bulto´,† Carmen Claver,*,† and Christine J. Cardin‡
Departament de Qu´ımica, Universitat Rovira i Virgili, Pl. Imperial Tarraco, 1, 43005 Tarragona, Spain,
and Department of Chemistry, The University of Reading, Whiteknights, P.O. Box 224, Reading RG6
6AD, U.K.
ReceiVed May 9, 1997
Palladium-rhodium and platinum-rhodium heterobimetallic bridged dithiolate complexes of general formula
[(P-P)M(µ-S-S)Rh(COD)]ClO4 (COD ) 1,5-cyclooctadiene. For M ) Pt: P-P ) (PPh3)2 and S-S ) EDT2-
(1,2-ethanedithiolate) (1), PDT2- (1,3-propanedithiolate) (2), and BDT2- (1,4-buthanedithiolate) (3); P-P ) dppb
(1,4-bis(diphenylphosphino)butane) and S-S ) EDT2- (4), PDT2- (5), and BDT2- (6); P-P ) dppp (1,3-bis-
(diphenylphosphino)propane) and S-S ) EDT2- (7), PDT2- (8), and BDT2- (9). For M ) Pd: P-P ) dppb
and S-S ) EDT2- (10), PDT2- (11), and BDT2- (12); P-P ) dppp and S-S ) EDT2- (13), PDT2- (14), and
BDT2- (15)) have been prepared. The crystal structures for complexes 1-3, 6, 9, and 12 have been determined,
and hinged structures were found with angles between local coordination planes MS2Rh ranging from 111.27°
for complex 1 to 151.34° for complex 3. Metal-metal distances show nonbonding interactions between metals.
X-ray data for 1: triclinic, P1h, a ) 11.311(6) Å, b ) 12.991(6) Å, c ) 16.140(6) Å, R ) 84.86(6)°, â ) 75.73(6)°,
γ ) 86.43(6)°, Z ) 2, R ) 0.0427 (Rw ) 0.1151). X-ray data for 2: triclinic, P1h, a ) 11.084(5) Å, b ) 13.094(6)
Å, c ) 16.338(6) Å, R ) 86.06(6)°, â ) 75.67(6)°, γ ) 88.55(6)°, Z ) 2, R ) 0.0470 (Rw ) 0.1264). X-ray data
for 3: orthorhombic, Pbca, a ) 14.439(6) Å, b ) 19.807(6) Å, c ) 38.156(6) Å, Z ) 8, R ) 0.0864 (Rw
)
0.2457). X-ray data for 6: monoclinic, P21/c, a ) 20.338(6) Å, b ) 14.227(6) Å, c ) 14.570(6) Å, â ) 100.94(6)°,
Z ) 4, R ) 0.0536 (Rw ) 0.1449). X-ray data for 9: monoclinic, P21/c, a ) 20.326(6) Å, b ) 14.109(6) Å, c
) 14.368(6) Å, â ) 100.90(6)°, Z ) 4, R ) 0.0380 (Rw ) 0.0990). X-ray data for 12: monoclinic, P21/c, a )
20.365(6) Å, b ) 14.186(6) Å, c ) 14.592(6) Å, â ) 101.04(6)°, Z ) 4, R ) 0.0507 (Rw ) 0.1500).
Introduction
disymmetric structural donor units such as N-C-P3,4 (pyri-
dine-phosphine), As-C-P5 (arsino-phosphine), and N-C-
S6 (benzothiazole-2-thiolate), the last of which is anionic.
Heterodonor ligands are especially appropriate for the synthesis
of hetero-bimetallic complexes, but their disymmetric nature
can yield two possible arrangements: head-to-head or head-to-
tail.
Interest in homo- and hetero-bimetallic complexes has
increased in the last few years due to the fact that the reactivity
and properties of a metal may be strongly modified by the
presence of another metallic center in close proximity. Two
bonded or close nonbonded metal atoms may react in a
cooperative manner with substrate molecules.1 Furthermore,
the electrochemical behavior of one metallic center may be
modified by the presence of a different metal in the same
molecule bonded directly or connected through a bridging ligand
that may act as an electron transmitter.2 Moreover, heterobi-
metallic complexes are of great interest as starting materials
for the preparation of cluster compounds.1a
Monodentate bridging ligands such as anionic thiolates (RS-)7
separate the metals by one atom and provide flexible structures
that support a wide range of bonding and nonbonding metal-
metal distances. However, the substituents, when present on
the donor sulfur atom, can adopt different relative orientations,
and thus complexes can have the syn and anti configurations.
Therefore, the structures of dinuclear complexes, homo- or
hetero-bimetallic with monothiolate bridged ligands, are rather
flexible, and their structures can range from planar to bent, with
Heterobimetallic complexes have mainly been prepared by
using mono- or bidentate bridging ligands which favor metal-
metal interaction. Of the bidentate ligands, a major role has
been played by the homodonor neutral diphosphine Ph2PCH2-
PPh2 (dppm),3 containing the donor structural unit P-C-P. This
approach can be modified by using heterodonor ligands with
(3) (a) Balch, A. L. In Homogeneous Catalysis with Metal Phosphine
Complexes; Pignolet, L. H., Ed.; Plenum Press: New York, 1983; pp
167-213. (b) Chaudret, B.; Delavaux, B.; Poilblanc, R. Coord. Chem.
ReV. 1988, 86, 191.
(4) Farr, J. P.; Olmstead, M. M.; Wood, F. E.; Rutherford, N. M.; Balch,
A. L. Organometallics 1983, 2, 1758 and references cited therein.
(5) (a) Balch, A. L.; Guimerans, R. R.; Linehan, J.; Wood, F. E. Inorg.
Chem. 1985, 24, 2021. (b) Balch, A. L.; Guimerans, R. R.; Linehan,
J.; Olmstead, M. M.; Oram, D. E. Organometallics 1985, 4, 1445.
(6) Ciriano, M. A.; Pe´rez-Torrente, J. J.; Lahoz, F. J.; Oro, L. A. Inorg.
Chem. 1992, 31, 969, and references cited therein.
(7) (a) Jain, V. K. Inorg. Chim. Acta. 1987, 133, 261. (b) Capdevila, M.;
Gonzalez-Duarte, P.; Foces-Foces, C.; Herna´ndez Cano, F.; Mart´ınez-
Ripoll, M. J. Chem. Soc., Dalton Trans. 1990, 143. (c) Amador, U.;
Delgado, E.; Fornie´s, J.; Herna´ndez, E.; Lalinde, E.; Moreno, M. T.
Inorg. Chem. 1995, 34, 5279.
† Universitat Rovira i Virgili.
‡ The University of Reading.
(1) (a) Braunstein, P.; Rose, J. In ComprehensiVe Organometallic
Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.;
Pergamon: Oxford, U.K., 1995; Vol. 10. (b) Savin, A.; Hengtai, Y.;
Chaquin, P. J. Organomet. Chem. 1984, 262, 391. (c) Poilblanc, R.
Inorg. Chim. Acta 1982, 62, 75.
(2) Zhou, M.; Xu, Y.; Tan, A.-M.; Leung, P.-H.; Mok, K. F.; Koh, L.-L.;
Hor, T. S. A. Inorg. Chem. 1995, 34, 6425.
S0020-1669(97)00557-0 CCC: $15.00 © 1998 American Chemical Society
Published on Web 05/06/1998

Heterobimetallic d8-d8 Complexes
Inorganic Chemistry, Vol. 37, No. 11, 1998 2627
carried out with a Carlo-Elba microanalyzer. Mass spectra were
recorded on a V. G. Autospec spectrometer.
hinged angles between local coordination planes MS2M (θ) less
than 180°.8 The distances between the metals are longer when
the structure is planar, so metal-metal interactions are less
favored. Even for bent structures, the estimated barrier energies
of the hinge motion are low8 and intermetallic interactions, if
there are any, are frequently weak in these kinds of complexes.9
The use of alkyl dithiolates, -S(CH2)nS-, with a few
methylenic units n, produces only the syn conformers and bent
structures and makes the systems less flexible than monothiolate
ones. More rigid systems could decrease the conformational
mobility of the intermediates providing different reactivity.
Safety Note. Initially, we attempted to prepare the complexes with
the tetrafluoroborate counteranion, but because of the greater facility
to crystallize with the perchlorate anion, the complexes were isolated
as perchlorate salts. We worked with these complexes in a number of
organic solvents without any incident, and as solids, they seem to be
very stable to shock and heat. Nevertheless, due to the unpredictable
behavior of perchlorate salts,14 they should be handled with extreme
care.
Perchlorate salts of metal complexes with organic ligands are
potentially explosive. Only small amounts of material should be
prepared, and these should be handled with great caution.
Recent studies have discussed the preparation of homo-
dinuclear and tetranuclear rhodium(I) complexes with alkyl
dithiolate bridging ligands [Rh2(µ-S(CH2)nS)(COD)2]x (x ) 1,
n ) 2 and 3; x ) 2, n ) 4),10 and their catalytic activity in the
hydroformylation of olefins has been investigated.11 Alkyl
dithiolates have considerable potential as bridging ligands for
synthesizing hetero-bimetallic complexes, and this aspect has
scarcely been studied.12
[(L)2M(µ-dithiolate)Rh(COD)]ClO4 (M ) Pt, Pd; dithiolate )
EDT, PDT, BDT; (L)2 ) (PPh3)2, dppb, dppp). General Procedure
for 1-15. A stoichiometric amount of [Rh(COD)2]ClO4 was added
to a solution of the corresponding mononuclear compound [M(dithi-
olate)(L)2] in dichloromethane (5 mL approximately), and the mixture
was stirred at room temperature for 30 min. The reaction was controlled
by thin-layer chromatography (TLC). The orange and yellow solutions
were concentrated to 2 mL approximately and the complexes were
isolated as microcrystalline solids by adding cold n-hexane. Crystals
of some of the compounds were obtained by slow diffusion of n-hexane
into a dichloromethane solution of the complexes.
[(PPh3)2Pt(µ-EDT)Rh(COD)]ClO4 (1). cis-[Pt(EDT)(PPh3)2] (0.0300
g, 0.0370 mmol) and [Rh(COD)2]ClO4 (0.0155 g, 0.0370 mmol), orange
crystals, 87% yield. 1H NMR (CDCl3, at 20 °C): δ 4.54 (m, 2 H,
-CHd, COD), 3.90 (m, 2 H, -CHd, COD), 2.40 (m, 2 H, -CH2-,
COD), 2.28 (m, 2 H, -CH2-, COD), 2.09 (m, 4 H, -CH2-, COD),
3.08 (m, 2 H, -CH2-, EDT), 2.55 (m, 2 H, -CH2-, EDT), 7.3-7.5
(m, 30 H, Ph, PPh3). 31P NMR (CDCl3, at 20 °C): δ 15.98 (J1(195Pt-
31P) ) 3219.9 Hz). Anal. Calcd for PtRhClS2P2O4C46H46: C, 49.18;
H, 4.10; S, 5.70. Found: C, 49.02; H, 4.31; S, 5.56.
[(PPh3)2Pt(µ-PDT)Rh(COD)]ClO4 (2). cis-[Pt(PDT)(PPh3)2] (0.0300
g, 0.0362 mmol) and [Rh(COD)2]ClO4 (0.0152 g, 0.0362 mmol), orange
crystals, 77% yield. 1H NMR (CDCl3, at 20 °C): δ 4.49 (m, 2 H,
-CHd, COD), 3.89 (m, 2 H, -CHd, COD), 2.45 (m, 2 H, -CH2-,
COD), 2.35 (m, 2 H, -CH2-, COD), 2.05 (m, 4 H, -CH2-, COD),
2.58 (m, 4 H, -SCH2-, PDT), 2.15 (m, 2 H, -CH2-, PDT), 7.3-7.5
(m, 30 H, Ph, PPh3). 31P NMR (CDCl3, at 20 °C): δ 17.93 (J1(195Pt-
31P) ) 3108.8 Hz). Anal. Calcd for PtRhClS2P2O4C47H48‚1/2CH2Cl2:
C, 48.35; H, 4.15; S, 5.43. Found: C, 48.05; H, 4.16; S, 5.26.
[(PPh3)2Pt(µ-BDT)Rh(COD)]ClO4 (3). cis-[Pt(BDT)(PPh3)2] (0.0300
g, 0.0358 mmol) and [Rh(COD)2]ClO4 (0.0150 g, 0.0358 mmol), yellow
crystals, 74% yield. 1H NMR (CDCl3, at 20 °C): δ 4.16 (m, 2 H,
-CHd, COD), 4.12 (m, 2 H, -CHd COD), 2.65 (m, 2 H, -CH2-,
COD), 2.10-2.30 (m, 4 H, -CH2-, COD), 1.98 (m, 2 H, -CH2-,
COD), 2.35 (m, 4 H, -SCH2-, BDT), 1.40 (m, 4 H, -CH2-, BDT),
7.2-7.6 (m, 30 H, Ph, PPh3). 31P NMR (CDCl3, at 20 °C): δ 19.13
(J1(195Pt-31P) ) 2915.2 Hz). Anal. Calcd for PtRhClS2P2O4C48H50‚
1/2CH2Cl2: C, 48.85; H, 4.27; S, 5.38. Found: C, 48.25; H, 4.18; S,
5.58.
[(dppb)Pt(µ-EDT)Rh(COD)]ClO4 (4). cis-[Pt(EDT)(dppb)] (0.0300
g, 0.0420 mmol) and [Rh(COD)2]ClO4 (0.0176 g, 0.0420 mmol), yellow
solid, 75% yield. 1H NMR (CDCl3, at 20 °C): δ 4.25 (m, 2 H, -CHd,
COD), 3.22 (m, 2 H, -CHd, COD), 2.80 (m, 4 H, -CH2-, COD),
1.85 (m, 2 H, -CH2-, COD), 1.65 (m, 2 H, -CH2-, COD), 2.81 (m,
2 H, -CH2-, EDT), 2.52 (m, 2 H, -CH2-, EDT), 7.75 (m, 10 H, Ph,
dppb), 7.58 (m, 5 H, Ph, dppb), 7.51 (m, 5 H, Ph, dppb), 2.80 (m, 4 H,
-PCH2-, dppb), 2.12 (m, 4 H, -CH2-, dppb). 31P NMR (CDCl3, at
20 °C): δ 15.33 (J1(195Pt-31P) ) 3127.9 Hz). FAB: m/z 924 [M -
ClO4]+. Anal. Calcd for PtRhClS2P2O4C38H40‚1/2CH2Cl2: C, 43.38;
H, 4.22; S, 6.04. Found: C, 43.15; H, 4.22; S, 5.90.
In this paper, we describe the preparation and X-ray deter-
mination of the first examples of hetero-bimetallic PtRh and
PdRh complexes of general formula [(phosphine)M(µ-dithio-
late)Rh(COD)]ClO4 (COD ) 1,5-cyclooctadiene). The syn-
thesis has been performed by reaction between the corresponding
mononuclear platinum or palladium dithiolate-phosphine com-
plex and the rhodium mononuclear complex [Rh(COD)2]ClO4.
Heterobimetallic complexes [(phosphine)M(µ-dithiolate)Rh-
(COD)]ClO4 are of interest because they can be modified in
any of their three ligand positions: the dithiolate bridging and
the different terminal positions of the two metals. It should be
pointed out that new complexes can be easily prepared by
controlling the synthesis of this type of hetero-bimetallic
compounds. By combining the characteristics of the ligands,
the properties of the whole complex may be tuned.
Experimental Section
All reactions were carried out under nitrogen atmosphere using
Schlenk techniques. Solvents were dried by standard methods and
distilled under nitrogen prior to use. Starting materials [Pt(EDT)-
(PPh3)2],13a [Pt(PDT)(PPh3)2],13b [Pt(BDT)(PPh3)2],13c [Pt(EDT)(dppb)],13d
[Pt(PDT)(dppb)],13d [Pt(EDT)(dppp)],13d [Pt(PDT)(dppp)],13d [Pt(BDT)-
(dppb)],13c [Pt(BDT)(dppp)],13c [Pd(BDT)(dppb)],13c and [Pd(BDT)-
(dppp)]13c were prepared using already described procedures. Com-
plexes which had not been previously described, [Pd(EDT)(dppb)],
[Pd(PDT)(dppb)], [Pd(EDT)(dppp)], and [Pd(PDT)(dppp)], were pre-
pared by a similar method.13 The 1H and 31P NMR spectra were
recorded on a Varian Gemini 300 spectrometer. Chemical shifts are
reported in parts per million relative to external standards (tetrameth-
1
ylsilane (TMS) for H and H3PO4 for 31P). Elemental analyses were
(8) Capdevila, M.; Clegg, W.; Gonza´lez-Duarte, P.; Jarid, A.; Lledo´s, A.
Inorg. Chem. 1996, 35, 490.
(9) (a) Bonnet, J.-J.; Kalck, P.; Poilblanc, R. Inorg. Chem. 1977, 16, 1514.
(b) Bonnet, J.-J.; Thorez, A.; Maisonnat, A.; Galy, J.; Poilblanc, R. J.
Am. Chem. Soc. 1979, 101, 5940. (c) Uso´n, R.; Oro, L. A.; Ciriano,
M. A.; Pinillos, M. T.; Tiripicchio, A.; Tiripicchio-Camellini, M. J.
Organomet. Chem. 1981, 205, 247.
(10) Masdeu, A. M.; Ruiz, A.; Castillo´n, S.; Claver, C.; Hitchcock, P. B.;
Chaloner, P. A.; Bo´, C.; Poblet, J. M.; Sarasa, P. J. Chem. Soc., Dalton
Trans. 1993, 2689.
(11) Aaliti, A.; Masdeu, A. M.; Ruiz, A.; Claver, C. J. Organomet. Chem.
1995, 489, 101.
(12) Aggarwal, R. C.; Mitra, R. Ind. J. Chem., A 1994, 33, 55.
(13) (a) Rauchfuss, T. B.; Roundhill, D. M. J. Am. Chem. Soc. 1975, 97,
3386. (b) Rauchfuss, T. B.; Shu, J. S.; Roundhill, D. M. Inorg. Chem.
1976, 15, 2096. (c) Fornie´s-Ca´mer, J.; Aaliti, A.; Ruiz, N.; Masdeu-
Bulto´, A. M.; Claver, C.; Cardin, C. J. J. Organomet. Chem., in press.
(d) Fazlur-Rahnam, A. K.; Verkade, J. G. Inorg. Chem. 1992, 31, 969.
[(dppb)Pt(µ-PDT)Rh(COD)]ClO4 (5). cis-[Pt(PDT)(dppb)] (0.0300
g, 0.0412 mmol) and [Rh(COD)2]ClO4 (0.0173 g, 0.0412 mmol), orange
solid, 69% yield. 1H NMR (CDCl3, at 20 °C): δ 4.30 (m, 2 H, -CHd,
(14) (a) Everett, K.; Graf, F. A., Jr. In CRC Handbook of Laboratory Safety,
2nd ed.; Steere, N. V., Ed.; Chemical Rubber Co.: Cleveland, OH,
1971. (b) Wolsey, W. C. J. Chem. Educ. 1973, 50, A335. (c) Raymond,
K. N. Chem. Eng. News 1983, 61 (Dec 5), 4.

2628 Inorganic Chemistry, Vol. 37, No. 11, 1998
Fornie´s-Ca´mer et al.
COD), 3.30 (m, 2 H, -CHd, COD), 2.25 (m, 4 H, -CH2-, COD),
1.95 (m, 2 H, -CH2-, COD), 1.72 (m, 2 H, -CH2-, COD), 2.90 (m,
4 H, -SCH2-, PDT), 2.40 (m, 2 H, -CH2-, PDT), 7.80 (m, 5 H, Ph,
dppb), 7.72 (m, 5 H, Ph, dppb), 7.51 (m, 10 H, Ph, dppb), 2.85 (m, 4
H, -PCH2-, dppb), 2.15 (m, 4 H, -CH2-, dppb). 31P NMR (CDCl3,
at 20 °C): δ 16.19 (J1(195Pt-31P) ) 3035.8 Hz). FAB: m/z 938 [M -
ClO4]+. Anal. Calcd for PtRhClS2P2O4C39H42‚1/2CH2Cl2: C, 43.93;
H, 4.35; S, 5.94. Found: C, 43.82; H, 4.31; S, 6.24.
[(dppb)Pt(µ-BDT)Rh(COD)]ClO4 (6). cis-[Pt(BDT)(dppb)] (0.0300
g, 0.0405 mmol) and [Rh(COD)2]ClO4 (0.0170 g, 0.0405 mmol), yellow
crystals, 74% yield. 1H NMR (CDCl3, at 20 °C): δ 4.12 (m, 4 H,
-CHd, COD), 2.30 (m, 4 H, -CH2-, COD), 2.15 (m, 2 H, -CH2-,
COD), 2.00 (m, 2 H, -CH2-, COD), 3.28 (m, 2 H, -SCH2-, BDT),
2.80 (m, 2 H, -SCH2-, BDT), 1.80 (m, 4 H, -CH2-, BDT), 8.20
(m, 5 H, Ph, dppb), 7.40-7.70 (m, 15 H, Ph, dppb), 2.55 (m, 4 H,
-PCH2-, dppb), 1.70 (m, 4 H, -CH2-, dppb). 31P NMR (CDCl3, at
20 °C): δ 17.69 (J1(195Pt-31P) ) 2909.9 Hz). Anal. Calcd for
PtRhClS2P2O4C40H44‚1/2CH2Cl2: C, 44.45; H, 4.47; S, 5.86. Found:
C, 44.20; H, 4.65; S, 5.96.
[(dppp)Pt(µ-EDT)Rh(COD)]ClO4 (7). cis-[Pt(EDT)(dppp)] (0.0300
g, 0.0427 mmol) and [Rh(COD)2]ClO4 (0.0179 g, 0.0427 mmol), yellow
solid, 72% yield. 1H NMR (CDCl3, at 20 °C): δ 4.25 (m, 2 H, -CHd,
COD), 3.12 (m, 2 H, -CHd, COD), 2.80 (m, 4 H, -CH2-, COD),
1.92 (m, 2 H, -CH2-, COD), 1.75 (m, 2 H, -CH2-, COD), 3.20 (m,
2 H, -CH2-, EDT), 2.55 (m, 2 H, -CH2-, EDT), 7.82 (m, 5 H, Ph,
dppp), 7.70 (m, 5 H, Ph, dppp), 7.52 (m, 5 H, Ph, dppp), 7.41 (m, 5 H,
Ph, dppp), 2.80 (m, 4 H, -PCH2-, dppp), 2.15 (m, 2 H, -CH2-, dppp).
31P NMR (CDCl3, at 20 °C): δ 0.01 (J1(195Pt-31P) ) 3004.5 Hz).
FAB: m/z 910 [M - ClO4]+. Anal. Calcd for PtRhClS2P2O4C37H38‚
1/2CH2Cl2: C, 42.81; H, 4.08; S, 6.09. Found: C, 42.49; H, 4.06; S,
6.12.
[(dppp)Pt(µ-PDT)Rh(COD)]ClO4 (8). cis-[Pt(PDT)(dppp)] (0.0300
g, 0.0420 mmol) and [Rh(COD)2]ClO4 (0.0176 g, 0.0420 mmol), orange
solid, 81% yield. 1H NMR (CDCl3, at 20 °C): δ 4.40 (m, 2 H, -CHd,
COD), 3.60 (m, 2 H, -CHd, COD), 3.15 (m, 4 H, -CH2-, COD),
2.01 (m, 2 H, -CH2-, COD), 1.35 (m, 2 H, -CH2-, COD), 2.85 (m,
4 H, -SCH2-, PDT), 2.35 (m, 2 H, -CH2-, PDT), 7.85 (m, 5 H, Ph,
dppp), 7.70 (m, 5 H, Ph, dppp), 7.50 (m, 10 H, Ph, dppp), 2.31 (m, 4
H, -PCH2-, dppp), 2.01 (m, 2 H, -CH2-, dppp). 31P NMR (CDCl3,
at 20 °C): δ 0.60 (J1(195Pt-31P) ) 2919.4 Hz). FAB: m/z 924 [M -
ClO4]+. Anal. Calcd for PtRhClS2P2O4C38H40‚1/2CH2Cl2: C, 42.25;
H, 4.14; S, 5.78. Found: C, 42.18; H, 4.03; S, 5.76.
[(dppp)Pt(µ-BDT)Rh(COD)]ClO4 (9). cis-[Pt(BDT)(dppp)] (0.0300
g, 0.0412 mmol) and [Rh(COD)2]ClO4 (0.0173 g, 0.0412 mmol), yellow
crystals, 70% yield. 1H NMR (CDCl3, at 20 °C): δ 4.21 (m, 4 H,
-CHd, COD), 2.55 (m, 4 H, -CH2-, COD), 2.32 (m, 2 H, -CH2-,
COD), 1.95 (m, 2 H, -CH2-, COD), 2.80 (m, 4 H, -SCH2-, BDT),
1.95 (m, 4 H, -CH2-, BDT), 8.20 (m, 5 H, Ph, dppp), 7.70-7.40 (m,
15 H, Ph, dppp), 2.12 (m, 4 H, -PCH2-, dppp), 1.92 (m, 2 H, -CH2-,
dppp). 31P NMR (CDCl3, at 20 °C): δ 1.14 (J1(195Pt-31P) ) 2785.7
Hz). Anal. Calcd for PtRhClS2P2O4C39H42‚1/2CH2Cl2: C, 44.04; H,
4.36; S, 5.95. Found: C, 44.01; H, 4.50; S, 6.04.
[(dppb)Pd(µ-EDT)Rh(COD)]ClO4 (10). cis-[Pd(EDT)(dppb)]
(0.0300 g, 0.0478 mmol) and [Rh(COD)2]ClO4 (0.0201 g, 0.0478
mmol), orange solid, 70% yield. 1H NMR (CDCl3, at 20 °C): δ 4.28
(m, 2 H, -CHd, COD), 3.12 (m, 2 H, -CHd, COD), 3.00 (m, 4 H,
-CH2-, COD), 1.85 (m, 2 H, -CH2-, COD), 1.62 (m, 2 H, -CH2-,
COD), 2.80 (m, 2 H, -CH2-, EDT), 2.60 (m, 2 H, -CH2-, EDT),
7.72 (m, 10 H, Ph, dppb), 7.60 (m, 5 H, Ph, dppb), 7.51 (m, 5 H, Ph,
dppb), 2.60 (m, 4 H, -PCH2-, dppb), 2.12 (m, 4 H, -CH2-, dppb).
31P NMR (CDCl3, at 20 °C): δ 25.68. FAB: m/z 835 [M - ClO4]+.
Anal. Calcd for PdRhClS2P2O4C38H40‚CH2Cl2: C, 45.93; H, 4.51; S,
6.29. Found: C, 45.48; H, 4.51; S, 6.32.
849 [M - ClO4], 741 [M - COD - ClO4], 423 [M - dppb - ClO4].
Anal. Calcd for PdRhClS2P2O4C39H42‚CH2Cl2: C, 46.47; H, 4.64; S,
6.20. Found: C, 46.12; H, 4.62; S, 6.22.
[(dppb)Pd(µ-BDT)Rh(COD)]ClO4 (12). cis-[Pd(BDT)(dppb)]
(0.0300 g, 0.0460 mmol) and [Rh(COD)2]ClO4 (0.0193 g, 0.0460
mmol), red cyrstals, 69% yield. 1H NMR (CDCl3, at 20 °C): δ 4.19
(m, 2 H, -CHd, COD), 3.99 (m, 2 H, -CHd, COD), 2.29 (m, 4 H,
-CH2-, COD), 2.12 (m, 2 H, -CH2-, COD), 2.02 (m, 2 H, -CH2-,
COD), 3.38 (m, 2 H, -SCH2-, BDT), 2.62 (m, 2 H, -SCH2-, BDT),
1.90 (m, 2 H, -CH2-, BDT), 1.62 (m, 2 H, -CH2-, BDT), 8.20 (m,
5 H, Ph, dppb), 7.4-7.8 (m, 15 H, Ph, dppb), 2.53 (m, 4 H, -PCH2-,
dppb), 1.70 (m, 4 H, -CH2-, dppb). 31P NMR (CDCl3, at 20 °C): δ
26.89. Anal. Calcd for PdRhClS2P2O4C39H42: C, 48.37; H, 4.97; S,
6.37. Found: C, 48.06; H, 5.05; S, 6.32.
[(dppp)Pd(µ-EDT)Rh(COD)]ClO4 (13). cis-[Pd(EDT)(dppp)]
(0.0300 g, 0.0491 mmol) and [Rh(COD)2]ClO4 (0.0206 g, 0.0491
mmol), orange solid, 84% yield. 1H NMR (CDCl3, at 20 °C): δ 4.30
(m, 2 H, -CHd, COD), 3.15 (m, 2 H, -CHd, COD), 3.00 (m, 4 H,
-CH2-, COD), 1.95 (m, 2 H, -CH2-, COD), 1.75 (m, 2 H, -CH2-,
COD), 3.15 (m, 2 H, -CH2-, EDT), 2.65 (m, 2 H, -CH2-, EDT),
7.72 (m, 10 H, Ph, dppp), 7.52 (m, 5 H, Ph, dppp), 7.47 (m, 5 H, Ph,
dppp), 2.65 (m, 4 H, -PCH2-, dppp), 2.15 (m, 2 H, -CH2-, dppp).
31P NMR (CDCl3, at 20 °C): δ 9.94. FAB: m/z 821 [M - ClO4]+.
Anal. Calcd for PdRhClS2P2O4C37H38‚1/2CH2Cl2: C, 46.60; H, 4.34;
S, 6.63. Found: C, 46.28; H, 4.40; S, 6.63.
[(dppp)Pd(µ-PDT)Rh(COD)]ClO4 (14). cis-[Pd(PDT)(dppp)]
(0.0300 g, 0.0478 mmol) and [Rh(COD)2]ClO4 (0.0201 g, 0.0478
mmol), orange solid, 77% yield. 1H NMR (CDCl3, at 20 °C): δ 4.40
(m, 2 H, -CHd, COD), 3.60 (m, 2 H, -CHd, COD), 3.20 (m, 4 H,
-CH2-, COD), 1.85 (m, 2 H, -CH2-, COD), 1.40 (m, 2 H, -CH2-,
COD), 2.70 (m, 4 H, -SCH2-, PDT), 2.30 (m, 2 H, -CH2-, PDT),
7.85 (m, 5 H, Ph, dppp), 7.65 (m, 5 H, Ph, dppp), 7.45 (m, 10 H, Ph,
dppp), 2.30 (m, 4 H, -PCH2-, dppp), 2.05 (m, 2 H, -CH2-, dppp).
31P NMR (CDCl3, at 20 °C): δ 8.70. FAB: m/z 835 [M - ClO4]+.
Anal. Calcd for PdRhClS2P2O4C38H40‚CH2Cl2: C, 45.93; H, 4.51; S,
6.29. Found: C, 45.96; H, 4.48; S, 6.27.
[(dppp)Pd(µ-BDT)Rh(COD)]ClO4 (15). cis-[Pd(BDT)(dppp)]
(0.0300 g, 0.0470 mmol) and [Rh(COD)2]ClO4 (0.0197 g, 0.0470
mmol), orange solid, 66% yield. 1H NMR (CDCl3, at 20 °C): δ 4.27
(m, 2 H, -CHd, COD), 4.09 (m, 2 H, -CHd, COD), 2.57 (m, 4 H,
-CH2-, COD), 2.32 (m, 2 H, -CH2-, COD), 2.02 (m, 2 H, -CH2-,
COD), 3.07 (pt, 4 H, -SCH2-, BDT), 1.85 (m, 4 H, -CH2-, BDT),
8.15 (m, 5 H, Ph, dppp), 7.2-7.7 (m, 15 H, Ph, dppp), 2.17 (m, 4 H,
-PCH2-, dppp), 2.02 (m, 2 H, -CH2-, dppp). 31P NMR (CDCl3, at
20 °C): δ 9.38. FAB: m/z 850 [MH - ClO4]+. Anal. Calcd for
PdRhClS2P2O4C39H42‚CH2Cl2: C, 46.46; H, 4.64; S, 6.20. Found: C,
46.26; H, 4.72; S, 6.32.
Crystal Data for the Compounds 1-3, 6, 9, and 12. Suitable
crystals of the complexes 1-3, 6, 9, and 12 were grown by diffusing
n-hexane into a solution of the above compounds in dichloromethane
and mounted on a glass fiber. The data were collected and processed
at room temperature on a Mar Research image plate scanner, graphite-
monochromated Mo ΚR radiation was used to measure 95/2° frames,
180 s per frame in all cases, except for compound 3 where 1200 s
exposure was used.
Compound 1: PtRhClS2P2O6C46H46, M ) 1154.34, triclinic, a )
11.311(6) Å, b ) 12.991(6) Å, c ) 16.140(6) Å, R ) 84.85(6)°, â )
75.73(6)°, γ ) 86.43(6)°, V ) 2287.2 Å3, space group P1h (No. 2), Z
) 2, Dc ) 1.676 g‚cm-3, F(000) ) 1144. Orange, crystal dimensions
0.15 × 0.22 × 0.17 mm, µ(Mo ΚR) ) 36.82 cm-1
.
Compound 2: PtRhCl2S2P2O5C47.5H48, M ) 1193.82, triclinic, a )
11.084(5) Å, b ) 13.094(6) Å, c ) 16.338(6) Å, R ) 86.06(6)°, â )
75.67(6)°, γ ) 88.55(6)°, V ) 2291.9 Å3, space group P1h (No. 2), Z
) 2, Dc ) 1.730 g‚cm-3, F(000) ) 1184. Orange, crystal dimensions
[(dppb)Pd(µ-PDT)Rh(COD)]ClO4 (11). cis-[Pd(PDT)(dppb)]
(0.0300 g, 0.0470 mmol) and [Rh(COD)2]ClO4 (0.0197 g, 0.0470
mmol), orange solid, 74% yield. 1H NMR (CDCl3, at 20 °C): δ 4.30
(m, 2 H, -CHd, COD), 3.30 (m, 2 H, -CHd, COD), 2.2-1.7 (m, 8
H, -CH2-, COD), 2.82 (m, 4 H, -SCH2-, PDT), 2.0-2.2 (m, 2 H,
-CH2-, PDT), 7.74 (m, 5 H, Ph, dppb), 7.60 (m, 5 H, Ph, dppb), 7.55
(m, 10 H, Ph, dppb), 2.70 (m, 4 H, -PCH2-, dppb), 2.0-2.2 (m, 4 H,
-CH2-, dppb). 31P NMR (CDCl3, at 20 °C): δ 25.59. FAB: m/z
0.34 × 0.26 × 0.20 mm, µ(Mo ΚR) ) 37.32 cm-1
.
Compound 3: PtRhCl2S2P2O4C48.5H42, M ) 1184.79, orthorhombic,
a ) 14.439(6) Å, b ) 19.807(6) Å, c ) 38.156(6) Å, V ) 10912.4 Å3,
space group Pbca (No. 61), Z ) 8, Dc ) 1.442 g‚cm-3, F(000) ) 4680.
Yellow, crystal dimensions 0.43 × 0.20 × 0.24 mm, µ(Mo ΚR) )
31.34 cm-1
.

Heterobimetallic d8-d8 Complexes
Inorganic Chemistry, Vol. 37, No. 11, 1998 2629
Table 1. Crystal Data for Compounds 1-3, 6, 9, and 12
1
2
3
6
9
12
formula
PtRhClS2
P2O4C46H46
2H2O
1154.34
P1h
20
11.311(6)
12.991(6)
16.140(6)
84.86(6)
75.73(6)
86.43(6)
2287.2
2
PtRhClS2
P2O4C47H48
1/2CH2Cl2‚H2O
1193.82
P1h
PtRhClS2
P2O4C48H42
1/2CH2Cl2
1184.79
Pbca
PtRhClS2
P2O4C40H48
1/2CH2Cl2
1093.75
P21/c
PtRhClS2
P2O4C39H38
1/2CH2Cl2
1070.65
P21/c
PdRhClS2
P2O4C40H48
1/2CH2Cl2
1005.06
P21/c
solvent
fw, g‚mol-1
space group
temp, °C
a, Å
20
20
20
20
20
11.084(5)
13.094(6)
16.338(6)
86.06(6)
75.67(6)
88.55(6)
2291.9
14.439(6)
19.807(6)
38.156(6)
20.338(6)
14.227(6)
14.570(6)
20.326(6)
14.109(6)
14.368(6)
20.365(6)
14.186(6)
14.592(6)
b, Å
c, Å
R, deg
â, deg
100.94(6)
100.90(6)
101.04(6)
γ, deg
V, Å3
10912.4
8
4139.1
4
4046.2
4
4137.6
4
Z
2
λ(Mo KR) Å
F(calcd), g‚cm-3
µ(Mo KR), cm-1
0.710 73
1.676
36.82
0.0427
0.1151
0.710 73
1.730
37.32
0.0470
0.1264
0.710 73
1.442
31.34
0.0864
0.2457
0.710 73
1.755
41.22
0.0536
0.1449
0.710 73
1.758
42.15
0.0380
0.0990
0.710 73
1.613
11.81
0.0507
0.1500
a
R1
b
Rw2
b
2
2
2
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. Rw2 ) [∑w(Fo - Fc2)/∑w(Fo )2]1/2; w ) 1/[σ2(Fo ) + (0.1025P)2 + 21.43P], where P ) (max(Fo ,0) + 2Fc2)/3).
Compound 6: PtRhCl2S2P2O4C40.5H48, M ) 1093.75, monoclinic, a
) 20.338(6) Å, b ) 14.227(6) Å, c ) 14.570(6) Å, â ) 100.94(6)°, V
Results and Discussion
The best method for preparing hetero-bimetallic complexes
M1-M1′ has been shown to be the direct reaction between the
two mononuclear fragments M1 + M1′.1 Another possible
method described in the literature is the reaction between the
corresponding homo-dinuclear monothiolates M2 + M2′, but,
in these cases, yields were poor.7b The M1 + M1′ synthesis
can be tackled in two ways, depending on which of the
mononuclear fragments (M1 or M1′) contains the coordinated
dithiolate ligand. The syntheses described in this paper require
the mononuclear platinum or palladium dithiolate complexes
to be used because rhodium ones stabilize the dinuclear species
[L2Rh(µ-dithiolate)RhL2].10
) 4139.1 Å3, space group P21/c (No. 14), Z ) 4, Dc ) 1.755 g‚cm-3
,
F(000) ) 2168. Yellow, crystal dimensions 0.21 × 0.29 × 0.22 mm,
µ(Mo ΚR) ) 41.22 cm-1
.
Compound 9: PtRhCl2S2P2O4C39.5H38, M ) 1070.65, monoclinic, a
) 20.326(6) Å, b ) 14.109(6) Å, c ) 14.368(6) Å, â ) 100.90(6)°, V
) 4046.2 Å3, space group P21/c (No. 14), Z ) 4, Dc ) 1.758 g‚cm-3
,
F(000) ) 2100. Yellow, crystal dimensions 0.24 × 0.32 × 0.26 mm,
µ(Mo ΚR) ) 42.15 cm-1
.
Compound 12: PdRhCl2S2P2O6C40.5H48, M ) 1005.06, monoclinic,
a ) 20.365(6) Å, b ) 14.186(6) Å, c ) 14.592(6) Å, â ) 101.04(6)°,
V ) 4137.6 Å3, space group P21/c (No. 14), Z ) 4, Dc ) 1.613 g‚cm-3
,
F(000) ) 2040. Dark red, crystal dimensions 0.17 × 0.22 × 0.24
mm, µ(Mo ΚR) ) 11.81 cm-1
.
Previous studies13 reported the preparation of mononuclear
platinum and palladium complexes containing coordinated
dithiolates with the general formula of [M(dithiolate)(P-P)] (M
) Pt, Pd; dithiolate ) EDT2- (1,2-ethanedithiolate), PDT2- (1,3-
propanedithiolate), BDT2- (1,4-buthanedithiolate); P-P )
(PPh3)2, dppb (1,4-bis(diphenylphosphino)butane), and dppp
(1,3-bis(diphenylphosphino)propane)). Due to the presence of
the dithiolate nonbonding electrons, these complexes may be
expected to coordinate to a second metal. With the aim of
developing the potential of this species as metalloligands in the
synthesis of hetero-bimetallic complexes, we studied their
reactivity with the mononuclear complex [Rh(COD)2]ClO4, in
which it is known that one diolefin can be easily displaced.
Reaction between a dichloromethane solution of complex [Pt-
(S(CH2)2S)(PPh3)2] with the rhodium complex [Rh(COD)2]ClO4
at room temperature for 30 min leads to the formation of an
orange compound which is isolated in high yield (87%) by
adding hexane and characterized as the new hetero-binuclear
complex 1, [(PPh3)2Pt(µ-S(CH2)2S)Rh(COD)]ClO4 (reaction 1).
The XDS15 package was used to give the following: 7052 unique
reflections [merging R ) 0.0280] (1), 6888 [merging R ) 0.0281] (2),
9013 [merging R ) 0.1360] (3), 5588 [merging R ) 0.0380] (6), 6486
[merging R ) 0.0374] (9), 5708 [merging R ) 0.0494] (12).
The heavy atoms were found from the Patterson map using the
SHELX8616 program and refined subsequently from successive dif-
ference Fourier maps using SHELXL9317 by full-matrix least squares
of 553 (1), 579 (2), 319 (3), 511 (6), 501 (9), and 511 (12) variables,
to a final R-factor of 0.043 (1), 0.047 (2), 0.086 (3), 0.054 (6), 0.038
(9), and 0.051 (12) for 6332 (1), 6239 (2), 2120 (3), 4614 (6), 5343
(9), 4452 (12) reflections with [Fo] > 4σ(Fo). All atoms were revealed
by the Fourier map difference. Non-hydrogen atoms were refined
anisotropically (except the C atoms of the phenyl groups of the PPh3
ligand in complex 3, which were fixed by using a riding model in which
the C-C vector is fixed at 1.39 Å). A disorder produced by the motion
of the central methylenic C atoms in the BDT ligand can be seen in 3
-
and 6. In all cases, a disorder was found in ClO4 anion. Hydrogen
atoms were placed geometrically and then refined with fixed isotropic
atomic displacement parameters. The weighting scheme w ) 1/[σ2-
(Fo ) + (aP)2 + bP], where P ) (max(Fo ,0) + 2Fc2)/3, a ) 0.0742
(1), 0.0900 (2), 0.1577 (3), 0.1072 (6), 0.0621 (9), 0.1209 (15) and b
) 9.84 (1), 9.39 (2), 139.81 (3), 15.24 (6), 7.18 (9), 4.50 (12) with
σ(Fo) from counting statistics, gave satisfactory agreement analyses.
Data collection parameters including R ([Fo] > 4σ(Fo)) and R′ (all data)
values are summarized in Table 1.
2
2
[Pt(EDT)(PPh3)2] + [Rh(COD)2]ClO4 f
[(PPh3)2Pt(µ-EDT)Rh(COD)]ClO4
+ COD (1)
1
This reaction was highly selective in the formation of hetero-
bimetallic compound 1. Other species were not observed either
in solid state or in solution. This method was extended to a
series of several dithiolates and diphosphines (Scheme 1), and
in all cases the desired hetero-bimetallic complexes were
(15) Kabsch, W. J. Appl. Crystallogr. 1993, 26, 795.
(16) Sheldrick, G. M. SHELXS-86: Program for Crystal Structure Solutions;
University of Go¨ttingen: Go¨ttingen, Germany, 1986.
(17) Sheldrick, G. M. SHELXS-93: Program for Crystal Structure Solutions;
University of Go¨ttingen: Go¨ttingen, Germany, 1993.

2630 Inorganic Chemistry, Vol. 37, No. 11, 1998
Fornie´s-Ca´mer et al.
Scheme 1
Table 2. 31P{1H} NMR Spectra (δ, ppm) for Complexes 1-15 in
CDCl3 Solutions with H3PO4 as External Standard
complex
δ, ppm
1J, Hz
complex
δ, ppm
1J, Hz
1
2
3
4
5
6
7
8
15.98
17.93
19.13
15.33
16.19
17.69
0.01
3219.9
3108.8
2915.2
3127.9
3035.8
2909.9
3004.5
2919.4
9
10
11
12
13
14
15
1.14
25.68
25.59
26.89
9.94
8.70
9.38
2785.7
0.60
obtained in high yields. Therefore, it is an efficient way for
the preparation of hetero-bimetallic complexes which can be
generalized.
The hetero-binuclear nature of these species in the solid state
was shown by X-ray structural analysis for the complexes 1-3,
6, 9, and 12. FAB mass spectra of complexes 4, 5, 7, 8, 10,
and 11 had a signal at m/z which corresponded to the cationic
species [(P-P)M(µ-dithiolate)Rh(COD)]+.
Figure 1. COSY experiment for complex 1.
NMR Spectroscopic Characterization. The spectroscopic
data (1H NMR in the experimental section and 31P{1H} NMR
in Table 2) show that there are no redistribution reactions in
solution. The 31P{1H} NMR spectra show only one signal in
all of the complexes, as expected for equivalent phosphorus
atoms. In the case of platinum compounds the satellites
attributed to the 31P-195Pt coupling corresponding to the
coordinated phosphine were observed. The palladium com-
plexes show the singlet that is to be expected when the
diphosphine ligand coordinates to the palladium center.
As far as the 31P{1H} data for all of the complexes are
concerned, the influence of the diphosphine ring size on the
31P displacement previously reported for other diphosphine
complexes18 can be seen by comparing dppb and dppp com-
plexes. The dithiolate ring size has less influence on the 31P
signals, which was also the case in related mononuclear platinum
dithiolate complexes.13
For the platinum complexes 1-9, the coupling constants
1J(Pt-P) have higher values in the hetero-bimetallic complexes
than in the mononuclear ones13 (for example, 1J(Pt-P) is 3219.9
Hz for complex 1 and 2884 Hz for complex [Pt(S(CH2)2S)-
(PPh3)2]), which indicates that the M-P bond strengthens. This,
in turn, can be related to the weakening of the M-S bond due
to bridge coordination.
In the complexes 1-5, 7, 8, and 10-15, the olefinic protons
corresponding to the coordinated COD appear in the 1H NMR
spectra as two multiplet signals, as expected for a bent structure
with a different environment for each of the two different faces
of the coordination plane.10 However, in the BDT complexes
6 and 9 these signals are not resolved and appear as a broad
signal. Because of the bent structure and the endo- and exo-
positions of methylenic COD protons, four non-equivalent sites
should be expected for methylenic COD protons. However,
all of the non-equivalencies are not resolved, and the spectra
show only three signals for all of the complexes 1-15 (except
for complex 11 for which a broad signal is observed).
As far as the dithiolate protons for complex 1 and the rest of
the complexes with EDT2- (4, 7, 10, and 13) are concerned,
the resonances attributed to the methylenic groups of the
dithiolate bridging ligands, which should be equivalent in a
homometallic environment, clearly split into two signals around
3.0 and 2.5 ppm. One of the signals may correspond to the
protons oriented to the platinum or palladium center and the
other to the rhodium center. This behavior is not observed for
the complexes with the PDT2- and BDT2- in which broad
signals were detected, probably due to conformational exchange
of the condensed six- and seven-membered metalocycles formed
by coordination to both metals.
The signals of the 1H NMR spectra were assigned by
correlation of 1H-1H COSY experiments due to the overlap of
the signals in the methylenic region. One example of the COSY
experiment for complex 1 is shown in Figure 1.
In order to determine which of the methylenic signals of the
1,2-ethanodithiolate correspond to the protons oriented to the
rhodium or platinum center, NOE experiments were performed
for complex 1. The more significative NOE effect values and
the proposed assignation of methylenic and olefinic signals for
(18) Garrou, P. E. Chem. ReV. 1981, 81, 229.

Heterobimetallic d8-d8 Complexes
Inorganic Chemistry, Vol. 37, No. 11, 1998 2631
Scheme 2
Scheme 3
Figure 2. X-ray structure for complex 1 showing thermal ellipsoids
at 50% probability.
occupied by coordinated COD. Crystal data and selected bond
distances and angles are summarized in Tables 1 and 3.
The rhodium-platinum and rhodium-palladium distances
range from 3.0096(6) Å for complex 1 to 3.4084 Å observed
for complex 3. These values are longer than the ones reported
for the metal-metal single bond (2.6 Å).19
Nevertheless, the Rh‚‚‚Pt separation for complex 1 (3.0096(6)
Å) is one of the shortest reported in the literature and is smaller
than that observed for face-to-face Pt‚‚‚Rh diphenylphosphi-
noarsino dimers5a such as trans-[Rh(CO)Cl(µ-dapm)2(cis-PtCl2)]
(dapm ) bis(diphenylarsino)methane) reported by Balch and
co-workers, where the Pt‚‚‚Rh distance was 3.043 Å. In these
cases, metal-metal interaction through the out-of-plane orbitals
was claimed. For bent structures, the orientation of the out-
of-plane orbitals will be less favorable but should not be rejected.
The influence of the size of the dithiolato metalloring in the
intermetallic distance can be detected in the complexes contain-
ing PPh3, 1-3. The Pt‚‚‚Rh distance increases from 1 to 3
according to the number of methylenic carbons between the
thiolato groups. This could be attributed to the consistent
increasing of the flexibility of the structure.
complex 1 are shown in Scheme 2. Irradiation of the HA
dithiolate proton is not conclusive because it produces a similar
NOE effect (0.8%) on the aromatic and olefinic protons.
However, when HB was irradiated, aromatic PPh3 signals show
enhancement of 9.8% and no NOE effect was observed on the
olefinic protons HC and HD. This suggests that HB protons may
be oriented to the platinum center that contains the phosphine
ligands and HA protons to the rhodium center. The inverse
experiments supported these results.
1
The H NMR spectra for complex 1 was unaltered in the
temperature range from +60 to -90 °C.
In the case of PDT2- complex 2, since the methylenic COD
protons appear as two broad signals, in the 1H NMR spectrum
at room temperature at 2.58 and 2.15 ppm, there may be an
equilibrium between the two different dithiolate ring conforma-
tions 2a and 2b (Scheme 3).
To confirm this, 1H NMR experiments were recorded at
different temperatures. Olefinic protons appear at +30 °C in
two broad signals, indicating a fast equilibrium between species
2a and 2b. When the temperature is decreased to -60 °C, a
slight broadening of these signals can be observed. At -90 °C
each signal split into two resonances in an 80:20 ratio with each
signal corresponding to one of the conformers. The same
behavior was detected in the 31P{1H} spectrum at -90 °C.
The X-ray study of complex 2, discussed below, shows that
the least sterically hindered conformer 2a is the more stable in
the solid state. According to these data, we propose that
structure 2a is the main species present in solution at -90 °C.
In an attempt to elucidate the mechanism of the substitution
reaction between [Pt(EDT)(PPh3)2] and [Rh(COD)2]ClO4, the
1H NMR of this mixture was performed at low temperature (-90
°C), but no intermediates could be detected and only the signals
corresponding to the starting materials and products were
observed.
Crystal Structures of Complexes 1-3, 6, 9, and 12. The
crystal structures of complexes 1-3, 6, 9, and 12 were
determined by X-ray diffraction analysis.
All complexes described here have similar structures, and,
as an example, Figure 2 shows the structure for complex 1.
They consist of discrete hetero-binuclear cationic units [(P-
P)M(µ-dithiolate)Rh(COD)]+ with the corresponding counter-
anions ClO4-. Cation complexes have a hinged structure where
dithiolates act as bridging ligands which coordinate both metals,
and the metal centers have square planar rearrangements. The
other coordination sites of platinum and palladium centers are
occupied by the phosphine ligands, while the rhodium ones are
Intermetallic distances are also sensitive to the phosphine
present in the platinum core. The Pt‚‚‚Rh distances for
complexes with the same dithiolato (BDT2-), 3, 6, and 9,
increase in the following order: dppp < dppb < PPh3. This
behavior could be attributed to the repulsion between the phenyl
groups and the ring constraints.
In the same way, of the BDT2- complexes 3, 6, and 9, those
containing PPh3 (complex 3) and the seven-membered dppb ring
(complex 6) show the largest P1-Pt-P2 angle (100.8(3) and
100.74(9)°, respectively), while the six-membered dppp ring
(complex 9) has a lower value (96.45(6)°). In contrast, the
values of the S-Pt-S, S-Pd-S, and S-Rh-S angles were
smaller than 90°, the smallest being the S-Pt-S angle,
78.73(7)°, for complex 1.
The torsion angle PtS2Rh θ (Scheme 4, Table 3) changes
with the variation in the metal-metal separations. It is smallest
for the complex with EDT, 1 (111.27°), and increases as the
dithiolato ring increases up to a value of 151.34° for complex
3. The corresponding homo-dinuclear rhodium(I) dithiolato
complexes [Rh(µ-EDT)(COD)]2 and [Rh(µ-PDT)(COD)]2, which
we have reported in a previous paper,10 both had torsion angles
of 104°.
The θ values observed for the complexes described in this
paper are, in general, slightly larger than the ones reported for
homo-binuclear thiolato complexes containing phosphorus-donor
ligands. Thus, θ for the phenylthiolato-bridged complex cis-
(19) See for example: (a) Farr, J. P.; Olmstead, M. M.; Balch, A. L. J.
Am. Chem. Soc. 1980, 102, 6654. (b) Guimerans, R. R.; Wood, F. E.;
Balch, A. L. Inorg. Chem. 1984, 23, 1307.

2632 Inorganic Chemistry, Vol. 37, No. 11, 1998
Fornie´s-Ca´mer et al.
Table 3. Selected Bond Distances (Å) and Angles (deg) for Complexes 1-3, 6, 9, and 12
1
2
3
6
9
12a
Pt-P1
Pt-P2
Pt-S1
Pt-S2
Pt-Rh1
Rh-S1
Rh-S2
2.285(2)
2.267(2)
2.358(2)
2.343(2)
3.0096(6)
2.372(2)
2.347(2)
2.297(2)
2.249(2)
2.345(2)
2.332(2)
3.0648(6)
2.370(2)
2.331(2)
2.274(7)
2.288(1)
2.341(1)
2.351(1)
3.4084
2.337(8)
2.358(11)
2.261(3)
2.260(2)
2.367(2)
2.354(3)
3.1984(8)
2.352(3)
2.351(2)
2.243(2)
2.256(2)
2.366(2)
2.259(2)
3.1592(6)
2.357(2)
2.353(2)
2.288(2)
2.282(2)
2.368(2)
2.357(2)
3.1718(7)
2.354(2)
2.352(2)
Rh-M*(C1-C2)b
Rh-M*(C5-C6)b
P2-Pt-P1
P2-Pt-S2
P1-Pt-S2
P2-Pt-S1
P1-Pt-S1
S2-Pt-S1
S1-Rh-S2
Pt-S1-Rh
Pt-S2-Rh
θ (PtS2Rh)
æ
2.030
2.035
2.007
2.022
2.019
2.072
2.039
2.030
2.026
2.039
2.039
2.027
97.25(6)
94.43(7)
168.03(7)
169.78(6)
90.02(6)
78.73(7)
78.38(7)
79.03(6)
79.83(6)
111.27
97.11(6)
91.37(7)
170.09(6)
173.38(6)
88.01(6)
83.17(7)
82.67(7)
81.08(6)
82.18(6)
121.42
100.8(3)
85.2(3)
173.5(3)
164.0(3)
91.5(3)
82.9(3)
82.9(3)
93.5(3)
92.7(3)
151.34
137.09
100.74(9)
86.80(10)
172.34(9)
167.76(9)
86.82(9)
85.52(9)
85.95(9)
85.33(8)
85.66(8)
135.67
96.45(6)
89.37(6)
173.78(6)
170.92(6)
87.63(6)
86.29(6)
86.65(6)
83.96(5)
84.21(5)
133.62
100.45(6)
86.20(7)
173.23(6)
168.11(7)
86.37(6)
86.86(6)
87.30(6)
84.42(6)
84.68(5)
136.24
96.02
104.91
129.91
132.30
132.16
a Pd complex. b M* ) medium point between olefinic carbons of COD.
Scheme 4
similar to the ones observed for mononuclear dithiolato-
diphosphino complexes.13c
As far as the conformation of the metalloring formed in
complex 2 is concerned, the crystal structure shows that the
methylene â to the thiolato group is oriented toward the rhodium
center as in species 2a (Scheme 3). In agreement with the
structure in the solid state, we have proposed that this
conformation is the main species observed by NMR in solution.
From the crystallographic data of the complexes discussed
here, it can be concluded that simple modifications in the alkyl
chain of the bridging dithiolates directly affect geometric
parameters such as metal-metal distances and the angles
between the coordination planes of the hinged structures. Thus,
the platinum-rhodium distance has been modified up to ca.
0.4 Å, and there have been variations in the coordination plane
angles up to 40°. Similarly, although to a lesser extent, the
terminal phosphine position of the platinum or palladium center
affects metal-metal distances and angles. These structural
changes may influence the chemical properties of these com-
plexes. In addition, further modifications in the electronic
properties of the ligands may give these complexes new
possibilities of reactivity.
[{Rh(µ-SPh)(CO)(PMe3)}2] is a value similar to that of complex
2 (113.0°),9a but a more sterically demanding thiolate in the
iridium complex cis-[{Ir(µ-SCMe3)(CO)(P(OMe)3)}2] increases
this value to 123.2°.9b
Another important geometric parameter to be considered is
the angle between coordination planes æ without considering
the metal coordinates (Scheme 4). In the case of the EDT2-
complex (1), the value of æ is 96.02°, which is very close to
the value for complex [Rh(µ-EDT)(COD)]2 (97°). The differ-
ence between the two parameters θ and æ in a particular
structure indicates a separation of the metals from their
coordination plane. This deviation was also observed for
complex [Rh(µ-EDT)(COD)]2 and was attributed to repulsion
between metals due to a short metal-metal nonbonding
distance.10
Metal-ligand distances are in the ranges reported for metal-
thiolate-phosphine complexes.13 Pt-P bond distances in
complex 1 (average 2.276 Å) decrease slightly with respect to
the corresponding mononuclear dithiolate complex cis-[Pt(EDT)-
(PPh3)2] (average 2.2885 Å)20 but are longer than those for the
mononuclear dichlorobis(triphenylphosphine)platinum(II) com-
plex cis-[PtCl2(PPh3)2] (2.251(2) and 2.265(2) Å.).21 The
variation in Pt-P distances is in agreement with the relative
values of 195Pt-31P coupling constants (2884.4 Hz for [Pt(EDT)-
(PPh3)2], 3219.9 Hz for complex 1, and 3513 Hz for
[PtCl2(PPh3)2] measured in CDCl3 with H3PO4 as external
standard).
In conclusion, a new route to hetero-bimetallic complexes
with bridging dithiolates [(P-P)M(µ-S-S)Rh(COD)]ClO4 has
been set up. The combination of different dithiolates in the
bridging position with different ligands in the terminal positions
(phosphine and diolefine) may allow the structural and electronic
parameters of these complexes to be finely tuned. The catalytic
activity in homogeneous processes and the reactivity of these
complexes are currently being investigated.
Acknowledgment. We thank the Ministerio de Educacio´n
y Ciencia and the Generalitat de Catalunya for financial support
(Grant QFN-95-4725-C03-2; CICYT-CIRIT).
Supporting Information Available: Figures showing ORTEP
1
projections of complexes 2, 3, 6, 9, and 12, and the H NMR spectra
of complex 1, the 1H NMR spectra in the methylenic region of complex
2, and the 31P{1H} NMR spectrum of complex 2 (8 pages). X-ray
crystallographic files, in CIF format, for complexes 1-3, 6, 9, and 12
are available on the Internet only. Ordering and access information is
given on any current masthead page.
The Pt-S and Pd-S bond lengths are not strongly influenced
by the variations in Pt-P and Pd-P bond values, which are
(20) Bryan, S. A.; Roundhill, D. M. Acta Crystallogr. 1983, C39, 184.
(21) Ferguson, G.; Anderson, K.; Clark, H. C.; Davies, J. A.; Parvez, M.
J. Crystallogr. Spectrosc. Res. 1982, 12, 449.
IC970557O