Mononuclear (Pd, Pt), heterodinuclear (PdAg, PtAg), and tetranuclear (Pd2Ag2, Pt2Ag2) 1,1-ethylenedithiolato complexes

Article abstract of DOI:10.1021/ic000996e

1p;&-5q; 1 The reactions of [Tl₂{S₂C=C{C(O)Me}₂}]_n with [MCl₂L₂] (1:1) or with [MCl₂(NCPh)₂] and PPh₃ (1:1:2) give complexes [M{η²-S₂C

Full text of DOI:10.1021/ic000996e

Inorg. Chem. 2001, 40, 2051-2057
2051
Mononuclear (Pd, Pt), Heterodinuclear (PdAg, PtAg), and Tetranuclear (Pd2Ag2, Pt2Ag2)
1,1-Ethylenedithiolato Complexes
Jose´ Vicente,*,† Mar´ıa Teresa Chicote, Sonia Huertas, and Delia Bautista‡
Grupo de Qu´ımica Organometa´lica, Departamento de Qu´ımica Inorga´nica,§ Facultad de Qu´ımica,
Universidad de Murcia, Apartado 4021, Murcia, 30071 Spain
Peter G. Jones*,|
Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Braunschweig, Postfach 3329,
38023 Braunschweig, Germany
Axel K. Fischer
Institut fu¨r Chemie, Universita¨t Magdeburg, Universita¨tsplatz 2, 37106 Magdeburg, Germany
ReceiVed August 31, 2000
lp;&-5q;1The reactions of [Tl2{S2CdC{C(O)Me}2}]n with [MCl2L2] (1:1) or with [MCl2(NCPh)2] and PPh3 (1:
1:2) give complexes [M{η2-S2CdC{C(O)Me}2}L2] [M ) Pt, L2 ) 1,5-cyclooctadiene (cod) (1); L2 ) bpy, M )
Pd (2a), Pt (2b), L ) PPh3, M ) Pd (3a), Pt (3b)] whereas with MCl2 and QCl (2:1:2) anionic derivatives
Q2[M{η2-S2CdC{C(O)Me}2}2] [M ) Pd, Q ) NMe4 (4a), Ph3PdNdPPh3 (PPN) (4a′), M ) Pt, Q ) NMe4
(4b)] are produced. Complexes 1 and 3 react with AgClO4 (1:1) to give tetranuclear complexes [{ML2}2Ag2-
{µ2,η2-(S,S′)-{S2CdC{C(O)Me}2}2}](ClO4)2 [L ) PPh3, M ) Pd (5a), Pt (5b), L2 ) cod, M ) Pt (5b′)], while
the reactions of 3 with AgClO4 and PPh3 (1:1:2) give dinuclear [{M(PPh3)2}{Ag(PPh3)2}{µ2,η2-(S,S′)-{S2Cd
C{C(O)Me}2}}]ClO4 [M ) Pd (6a), Pt (6b)]. The crystal structures of 3a, 3b, 4a, and two crystal forms of 5b
have been determined. The two crystal forms of 5b display two {Pt(PPh3)2}{µ2,η2-(S,S′)-{S2CdC{C(O)Me}2}2}
moieties bridging two Ag(I) centers.
Introduction
version processes.9 Much of the effort currently being expended
is devoted to finding how the excited-state properties can be
Certain ketene dithioacetals with electron-withdrawing sub-
stituents and certain 1,1-ethylenedithiolato metal complexes
display interesting photophysical properties.1-5 Indeed, the
increasing attention paid nowadays to these species arises from
their solvatochromic behavior and room-temperature lumines-
cence in solution6-8 and their status as excellent candidates for
applications as photocatalysts in light-to-chemical-energy con-
altered in a predictable manner through systematic ligand
modification.9 In addition, the use of 1,1-ethylenedithiolate
ligands may facilitate the syntheses of clusters10-14 or stabilize
unusually high oxidation states.15-17
Most 1,1-ethylenedithiolato metal complexes are mono-
nuclear,6-8,15-21 although some homopolynuclear complexes
with bridging or chelating 1,1-ethylenedithiolato ligands,22-24
Dedicated to Professor Rafael Uso´n on the occasion of his 75th
birthday.
(9) Paw, W.; Cummings, S. D.; Mansour, M. A.; Connick, W. B.; Geiger,
D. K.; Eisenberg, R. Coord. Chem. ReV. 1998, 171, 125.
(10) Hong, M. C.; Su, W. P.; Cao, R.; Jiang, F. L.; Liu, H. Q.; Lu, J. X.
Inorg. Chim. Acta 1998, 274, 229.
(11) McCandlish, L. E.; Bissell, E. C.; Coucouvanis, D.; Fackler, J. P.;
Knox, K. J. Am. Chem. Soc. 1968, 90, 7357.
(12) Hollander, F. J.; Coucouvanis, D. J. Am. Chem. Soc. 1977, 99, 6268.
(13) Birker, P. J. M. W. L.; Verschoor, G. C. J. Chem. Soc., Chem.
Commun. 1981, 322.
(14) Dietrich, H.; Storck, W.; Manecke, G. J. Chem. Soc., Chem. Commun.
1982, 1036.
† To whom correspondence should be addressed for the syntheses of
complexes. E-mail: jvs@um.es.
‡ To whom correspondence should be addressed for the X-ray diffraction
study of complex 4a. E-mail: dbc@um.es. Present address: S.A.C.E.
Universidad de Murcia, Apartado 4021, Murcia, 30071 Spain.
§ Web: http://www.scc.um.es/gi/gqo/.
| To whom correspondence should be addressed for the X-ray diffraction
studies of complexes 3a, 3b, and 5b. E-mail: jones@xray36.anchem.nat.tu-
bs.de.
(1) Mohanalingam, K.; Nethaji, M.; Das, P. K. J. Mol. Struct. 1996, 378,
177.
(2) Sandstro¨m, J.; Wennerbeck, I. Acta Chem. Scand. 1970, 24, 1191.
(3) Sandstrom, J.; Sjostrand, U. Tetrahedron 1978, 34, 3305.
(4) Smith, D.; Taylor, P. J. J. Chem. Soc., Perkin Trans. 2 1979, 1376.
(5) Colonna, F. P.; Distefano, G.; Sandstro¨m, J.; Sjo¨strand, U. J. Chem.
Soc., Perkin Trans. 2 1978, 279.
(15) Hollander, F. J.; Pedelty, R.; Coucouvanis, D. J. Am. Chem. Soc. 1974,
96, 4032.
(16) Hollander, F. J.; Caffery, M. L.; Coucouvanis, D. J. Am. Chem. Soc.
1974, 96, 4682.
(17) Coucouvanis, D.; Hollander, F. J.; Caffery, M. L. Inorg. Chem. 1976,
15, 1853.
(18) Weigand, W.; Saumweber, R.; Schulz, P. Z. Naturforsch. B 1993, 48,
1080.
(19) Pearson, R. G.; Sweigart, D. A. Inorg. Chem. 1970, 9, 1167.
(20) Weigand, W.; Bosl, G.; Polborn, K. Chem. Ber. 1990, 123, 1339.
(21) Zuleta, J. A.; Bevilacqua, J. M.; Proserpio, D. M.; Harvey, P. D.;
Eisenberg, R. J. Am. Chem. Soc. 1992, 31, 2396.
(6) Zuleta, J. A.; Burberry, M. S.; Eisenberg, R. Coord. Chem. ReV. 1990,
97, 47.
(7) Bevilacqua, J. M.; Zuleta, J. A.; Eisenberg, R. Inorg. Chem. 1993,
32, 3689.
(8) Bevilacqua, J. M.; Eisenberg, R. Inorg. Chem. 1994, 33, 1886.
10.1021/ic000996e CCC: $20.00 © 2001 American Chemical Society
Published on Web 03/24/2001

2052 Inorganic Chemistry, Vol. 40, No. 9, 2001
Vicente et al.
Table 1. Crystallographic Data for Complexes 3a, 3b, 4a, 5b‚C3H6O, and 5b‚2C4H10O
3a
3b
4a
5b‚C3H6O
5b‚2C4H10O
chemical formula
fw
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
C46H36O2P2PdS
805.17
Pbca (No. 61)
19.2590(5)
16.9889(5)
22.5659(6)
90
90
90
7383
8
1.449
0.74
-100
0.710 73
0.066
0.031
1.07
C46H36O2P2PdS
893.96
Pbca (No. 61)
19.290(3)
16.927(3)
22.475(3)
90
90
90
7338
8
1.618
4.06
-100
0.710 73
0.059
0.031
0.79
C20H36N2O4PdS4
603.15
Pbca (No. 61)
11.9402(11)
18.9221(12)
25.580(2)
90
90
90
5779.4
8
1.386
0.956
25
0.710 73
0.1731
0.0515
0.97
C87H78Ag2Cl2O13P4Pt2S4
2260.43
P1h (No. 2)
10.6869(10)
12.574(2)
16.482(2)
80.422(10)
73.741(10)
87.582(10)
2096.6
C92H92Ag2Cl2O14P4Pt2S4
2350.60
P21/n (No. 11)
11.0089(2)
29.4225(5)
14.0317(3)
90
100.846(10)
90
4463.8
2
1.749
3.85
-110
0.710 73
0.057
Z
F
1
calcd (g cm-3
)
1.790
4.09
-100
0.710 73
0.084
0.034
1.00
µ (mm-1
T (°C)
λ (Å)
)
Rw(F2, all reflns)a
R(F>4 σ(F))a
S a
0.032
1.03
a R1 ) ∑||Fo| - |Fc||/∑|Fo| for reflections with I > 2 σ(I). wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo )2]0.5 for all reflections; w-1 ) σ2(F2) + (aP)2 +
2
2
bP, where P ) (2Fc2 + Fo )/3 and a and b are constants set by the program. S ) [∑[w(Fo - Fc2)2]/(n - p)]0.5, where n is the number of the
reflections and p is the total number refined.
2
2
including clusters,10,13,25-27 are known. In a few 1,1-ethylene-
apparatus and are uncorrected. C, H, N, and S analyses were carried
1
out with a Carlo Erba 1106 microanalyzer. H and 13C NMR spectra
dithiolato “MFe” or “M2Fe” complexes of the type [{M(PPh3)2}n
were measured in CDCl3 or d6-dmso (2a, 2b) on a Varian Unity 300
{S2CdCCHC(O)R}] [M ) Pd, Pt; n ) 1, R ) {(η5-C5H4)2Fe-
spectrometer. Chemical shifts are given in ppm and referenced to TMS
(η5-C5H5)}; n ) 2, R ) {(η5-C5H4)2Fe}]28sobtained from
ferrocenyl-substituted 3-hydroxydithioacrylic acidsthe Fe atom
forms part of the R group. The only heterometallic complexes
in which 1,1-ethylenedithiolato ligands are assumed to bridge
(1H and 13C) or to H3PO4 (31P).
X-ray Structure Determinations of 3a, 3b, 5b‚Me2CO, 5b‚2Et2O,
and 4a. Numerical data are presented in Table 1. Crystals were mounted
on glass fibers (4a with glue) and transferred to the cold gas stream of
the diffractometer. Data were recorded with Mo KR radiation (λ )
0.710 73 Å) in ω-scan mode. Structures of 3a, 3b, 5b‚Me2CO and 5b‚
two different metal centers are a few of general formula
M[Ag2(S2CdC(CN)CO2Et)2] (M ) Co, Ni, Cu, Cd, Hg, Pd).29
Their proposed nature is based on a variety of techniques, but
unfortunately, none of them has been structurally characterized.
We report here the syntheses and structural characterization of
heterodinuclear (PdAg, PtAg) and -tetranuclear (Pd2Ag2, Pt2-
Ag2) 1,1-ethylenedithiolato derivatives. Complexes with the
ligand 2,2-diacetyl-1,1-ethylenedithiolato are extremely scarce.
Apart from some complexes of Tl(I), Au(I), and Au(III) recently
reported by us,30 only a few with Mn(II), Co(II), Ni(II), Cu(II),
Zn(II), and Cd(II) have been reported, but their nature was only
established by elemental analysis.31 We report here 2,2-diacetyl-
1,1-ethylenedithiolato complexes of palladium and platinum.
2Et2O were solved by direct methods and refined anisotropically on
F2 [program SHELXL-97 (4a SHELXL-93), G. M. Sheldrick, Univer-
sity of Go¨ttingen, Germany]. Hydrogen atoms were included using a
riding model or with rigid methyl groups. A special feature of
refinement is that in 5b‚Me2CO the acetone is disordered over two
positions.
[PtCl2(cod)] (cod ) 1,5-cyclooctadiene),32 [AuCl(tht)] (tht ) tet-
30
rahydrothiophene),33 [Tl2{S2CdC{C(O)Me}2}],
and CuCl34 were
prepared as previously reported. PPh3, NiCl2‚6H2O (Fluka), AgClO4
(Aldrich), CdCl2, and HgCl2 (Probus) were obtained from commercial
sources and used without further purification.
[Pt{η2-S2CdC{C(O)Me}2}(cod)] (1). Solid [PtCl2(cod)] (cod ) 1,5-
cyclooctadiene, 114.7 mg, 0.31 mmol) was added to a suspension of
[Tl2{η2-S2CdC{C(O)Me}2}] (180.7 mg, 0.31 mmol) in acetone (20
mL). A white precipitate in a yellow solution readily formed, and the
suspension was stirred for 30 min. The solvent was removed under
vacuum, the residue extracted with dichloromethane, and the extract
filtered through Celite. The solution was concentrated (3 mL) and
diethyl ether (40 mL) added to precipitate 1 as a yellow solid, which
was filtered and suction-dried. Yield: 129.5 mg, 87%. Anal. Calcd for
C14H18O2PtS2: C, 35.22; H, 3.80; S, 13.43. Found: C, 35.16; H, 3.71;
S, 13.30. Mp: 191 °C (dec). ΛM (Ω-1 cm2 mol-1): 2. IR (cm-1): 1674
Experimental Section
Infrared spectra were recorded in the range 4000-200 cm-1 on a
Perkin-Elmer 16F PC FT-IR spectrophotometer using Nujol mulls
between polyethylene sheets. We give only the values of ν(CdO) or
ν(CdC) stretching modes. Conductivities were measured with a Philips
PW9501 conductimeter. Melting points were determined on a Reichert
(22) Fackler, J. P.; Staples, R. J.; Assefa, Z. J. Chem. Soc., Chem. Commun.
1994, 431.
(23) Xiong, R.-G.; You, X.-Z.; Zuo, J.-L. Inorg. Chem. 1997, 36, 2472.
(24) Kang, B.-S.; Chen, Z.-N.; Su, C.-Y.; Lin, Z.; Wen, t.-B. Polyhedron
1998, 17, 2497.
(25) Fackler, J. P., Jr.; Staples, R. J.; Liu, C. W.; Stubbs, T.; Lopez, C.;
Pitts, J. T. Pure Appl. Chem. 1998, 70, 839.
(26) Dietrich, H.; Storck, W.; Manecke, G. J. Chem. Soc., Chem. Commun.
1982, 1036.
(27) Coucouvanis, D.; Swenson, D.; Baenziger, N. C.; Pedelty, R.; Caffery,
M. L.; Kanodia, S. Inorg. Chem. 1989, 28, 2829.
(28) Buchweitz, J.; Gompper, R.; Polborn, K.; Robl, C.; Sailer, M.-T.;
Weigand, W. Chem. Ber. 1994, 127, 23.
1
s, 1615 s, 1509 s, 1499 s, 1489 s. H NMR: δ 2.26-2.36 (m, 10 H,
Me + cod), 2.62 (m, 4 H, cod), 5.29 (s with Pt satellites, 4 H, cod,
2JPtH ) 57.9 Hz). 13C{1H} NMR: δ 30.71 (CH2, cod), 31.90 (Me),
100.84 (s with Pt satellites, CH, cod, JCPt ) 75.4 Hz), 136.89 (Cd
CS2), 175.20 (CdCS2), 196.95 (CO).
[M{η2-S2CdC{C(O)Me}2}(bpy)]‚nH2O [M ) Pd, n ) 1 (2a); M
) Pt, n ) 0 (2b)]. Solid [MCl2(bpy)] (bpy ) 2,2′-bipyridine, 214 mg,
0.64 mmol for 2a; 114.3 mg, 0.27 mmol for 2b) was added to a
(29) Singh, N.; Gupta, S. Polyhedron 1999, 18, 1265.
(30) Vicente, J.; Chicote, M. T.; Gonzalez-Herrero, P.; Jones, P. G.;
Humphrey, M. G.; Cifuentes, M. P.; Samoc, M.; Luther-Davies, B.
Inorg. Chem. 1999, 38, 5018.
(31) Malik, W. U.; Bembi, R.; Bharddwaj, V. K. J. Indian Chem. Soc.
1984, 65, 379.
(32) McDermott, J. X.; White, F. J.; Whitesides, G. M. J. Am. Chem. Soc.
1976, 98, 6521.
(33) Uso´n, R.; Laguna, J.; Vicente, J. J. Organomet. Chem. 1977, 131,
471.
(34) Jolly, W. L. Synthetic Inorganic Chemistry; Prentice-Hall: Englewood
Cliffs, NJ, 1960; pp 142-143.

1,1-Ethylenedithiolato Complexes
Inorganic Chemistry, Vol. 40, No. 9, 2001 2053
suspension containing an equimolar amount of [Tl2{η2-S2CdC{C(O)-
Me}2}] in chloroform (40 mL). The mixture was refluxed for 6 (2a)
or 6.5 (2b) h and filtered. The brown residue was extracted with
chloroform (2a, 3 × 40 mL) or dichloromethane (2b, 4 × 40 mL), and
the combined extracts were filtered through Celite and added to the
initial filtrate. The solution was concentrated (5 mL) and diethyl ether
(40 mL) added to precipitate a cream (2a) or orange (2b) solid that
was filtered, washed with diethyl ether (2 × 5 mL), and suction-dried.
2a. Yield: 198 mg, 69%. Anal. Calcd for C16H16N2O3PdS2: C, 42.25;
H, 3.55; N, 6.16; S, 14.10. Found: C, 42.78; H, 3.00; N, 6.26; S, 14.35.
Mp: 97 °C (dec). IR (cm-1): 1636 m, 1596 s, br. 1H NMR: δ 2.28 (s,
6 H, Me), 3.32 (s, H2O), 7.76 (t, 2 H, bpy), 8.30-8.35 (m, 4 H, bpy),
8.66 (d, 2 H, bpy). 13C{1H} NMR: δ 30.89 (Me), 123.81, 127.74 (bpy),
139.74 (CdCS2), 140.61, 148.66, 154.28 (bpy), 190.10 (CdCS2),
197.15 (CO).
[{ML2}2Ag2{µ2,η2-(S,S′)-{S2CdC{C(O)Me}2}2}](ClO4)2 [L ) PPh3,
M ) Pd (5a), Pt (5b), L2 ) cod, M ) Pt (5b′)]. To a solution of
[M{η2-S2CdC{C(O)Me}2}L2] [M ) Pd, 3a (154.3 mg, 0.19 mmol);
M ) Pt, 3b (101.8 mg, 0.11 mmol), or 1 (170.2 mg, 0.36 mmol)] in
acetone (20 mL) an equimolar amount of AgClO4 was added. The
resulting yellow solution was stirred for 1 (5a, 5b′) or 3 h (5b) in the
dark and filtered through Celite. The filtrate was concentrated (3 mL),
and diethyl ether (35 mL) was added to precipitate an off-white solid,
which was filtered, washed with diethyl ether (5 mL), and suction-
dried.
5a. Yield: 167 mg, 87%. Anal. Calcd for C84H72Ag2Cl2O12P4Pd2S4:
C, 49.82; H, 3.58; S, 6.33. Found: C, 49.62; H, 3.55; S, 6.69. Mp: 71
°C (dec). ΛM (Ω-1 cm2 mol-1): 313. IR (cm-1): 1667 s, 1091 s, 622
s, 514 s. 1H NMR: δ 2.13 (s, 12 H, Me), 7.07-7.47 (m, 60 H, PPh3).
31P{1H} NMR: δ 26.0 (s).
5b. Yield: 102 mg, 84%. Anal. Calcd for C84H72Ag2Cl2O12P4Pt2S4:
C, 45.81; H, 3.29; S, 5.82. Found: C, 45.34; H, 3.45; S, 5.45. Mp: 85
°C (dec). ΛM (Ω-1 cm2 mol-1): 345. IR (cm-1): 1686 s, 1667 s, 1521
2b. Yield: 91 mg, 64%. Anal. Calcd for C16H14N2O2PtS2: C, 36.57;
H, 2.69; N, 5.33; S, 12.20. Found: C, 36.03; H, 2.41; N, 5.36; S, 12.30.
1
Mp: 280 °C (dec). IR (cm-1): 1680 m, 1614 s, br. H NMR: δ 2.29
1
m, 1090 s, 622 s, 568 s, 536 s, 518 s, 507 s, 491 s. H NMR: δ 2.04
(s, 6 H, Me), 7.76 (t, 2 H, bpy), 8.41 (t, 2 H, bpy), 8.53 (d, 2 H, bpy),
8.68 (d, 2 H, bpy).
(s, 12 H, Me), 7.16-7.34 (m, 60 H, PPh3). 31P{1H} NMR: δ 18.78 (s
with Pt satellites, JPPt ) 3068 Hz). In various attempts to crystallize
complexes resulting from the reactions of 5b with [Ag(PPh3)(ClO4)],
1:1 and 1:2, crystals of 5b‚Me2CO (triclinic) and 5b‚2Et2O (mono-
clinic), respectively, were obtained; both modifications were studied
crystallographically.
[M{η2-S2CdC{C(O)Me}2}(PPh3)2] [M ) Pd (3a), Pt (3b)]. To a
suspension of [Tl2{η2-S2CdC{C(O)Me}2}] (256.5 mg, 0.44 mmol for
3a; 239.0 mg, 0.41 mmol for 3b) in dichloromethane (40 mL) were
added an equimolar amount of [MCl2(NCPh)2] and 2 equiv of PPh3.
After 10 min (3a) or 24 h (3b) of stirring, the suspension was filtered
through Celite, the solution concentrated (3 mL) under vacuum, and
diethyl ether (40 mL) added to precipitate 3a and 3b as yellow solids
that were filtered, washed with diethyl ether (2 × 5 mL), and suction
dried.
5b′. Yield: 226 mg, 92%. Anal. Calcd for C28H36Ag2Cl2O12Pt2S4:
C, 24.55; H, 2.67; S, 9.36. Found: C, 24.88; H, 2.50; S, 9.23. Mp:
173 °C (dec). ΛM (Ω-1 cm2 mol-1): 298. IR (cm-1): 1668 s, 1615 s,
1
1075 s, 620 s. H NMR: δ 2.22-2.33 [m, 28 H, Me + CH2 (cod)],
5.28 (s, br, with Pt satellites, 8 H, CH (cod), JHPt ) 55 Hz).
3a. Yield: 312 mg, 88%. Anal. Calcd for C42H36O2P2PdS2: C, 62.65;
H, 4.51; S, 7.96. Found: C, 62.90; H, 4.52; S, 7.59. Mp: 91 °C (dec).
[{M(PPh3)2}{Ag(PPh3)2}{µ2,η2-(S,S′)-{S2CdC{C(O)Me}2}}]-
ClO4 [M ) Pd (6a), Pt (6b)]. To a solution of the complex [M{η2-
S2CdC{C(O)Me}2}(PPh3)2] (3a, 157.2 mg, 0.20 mmol; 3b, 82.1 mg,
0.09 mmol) in acetone (40 mL) were added an equimolar amount of
AgClO4 and 2 equiv of PPh3. The resulting solution was stirred in the
dark for 2 (6a) or 4 h (6b). It was then concentrated (3 mL), and diethyl
ether (40 mL) was added to precipitate a pale-yellow solid that was
filtered, washed with diethyl ether (5 mL), and suction-dried.
6a. Yield: 230 mg, 75%. Anal. Calcd for C78H66AgClO6P4PdS2:
C, 60.95; H, 4.33; S, 4.17. Found: C, 60.80 H, 4.51; S, 3.92. Mp: 135
°C (dec). ΛM (Ω-1 cm2 mol-1): 116. IR (cm-1): 1680 s, 1658 m, 1089
1
IR (cm-1): 1658 s, 1630 s, 1091 s. H NMR: δ 2.25 (s, 6 H, Me),
7.18-7.38 (m, 30 H, Ph). 13C{1H} NMR: δ 31.69 (Me), 128.33 (m,
o-C, PPh3), 129.05 (m, ipso-C, PPh3), 130.72 (m, p-C, PPh3), 134.33
(m, m-C, PPh3), 137.00 (CdCS2), 187.04 (CdCS2), 198.03 (CO). 31P-
{1H} NMR: δ 29.71 (s). Crystals of 3a were grown from dichlo-
romethane/diethyl ether.
3b. Yield: 315 mg, 86%. Anal. Calcd for C42H36O2P2PtS2: C, 56.43;
H, 4.06; S, 7.17. Found: C, 56.06; H, 4.07; S, 7.30. Mp: 133 °C (dec).
1
IR (cm-1): 1659 s, 1636 s, 1092 m, 571 s, 537 s, 505 s, 455 s. H
NMR: δ 2.24 (s, 6 H, Me), 7.18-7.44 (m, 30 H, Ph). 13C{1H} NMR:
δ 32.07 (Me), 128.14 (m, o-C, PPh3), 129.11 (m, ipso-C), 130.87 (m,
p-C, PPh3), 134.47 (m, m-C, PPh3), 138.20 (CdCS2), 183.00 (CdCS2),
197.67 (CO). 31P{1H} NMR: δ 19.15 (s with Pt satellites, JPPt ) 3041
Hz). Single crystals of 3b were grown from acetone/diethyl ether.
Q2[M{η2-S2CdC{C(O)Me}2}2] [M ) Pd, Q ) NMe4 (4a), Ph3Pd
NdPPh3 (PPN) (4a′); M ) Pt, Q ) NMe4 (4b)]. To a suspension of
[Tl2{η2-S2CdC{C(O)Me}2}] (658.8 mg, 1.13 mmol for 4a; 697.8 mg,
1.20 mmol for 4a′; 618 mg, 1.06 mmol for 4b) in acetone (50 mL)
were added an equimolar amount of the corresponding MCl2 and 2
equiv of Me4NCl (4a, 4b) or PPNCl (4a′), and the mixture was refluxed
for 8 h. The solvent was removed under vacuum, and the residue was
extracted with dichloromethane (4 × 25 mL). The extracts were filtered
through Celite, the solution concentrated (3 mL), and diethyl ether (40
mL) added to precipitate orange (4a, 4a′) or brown-orange solids (4b)
that were filtered and dried under a N2 atmosphere.
1
s, 621 s, 512 s. H NMR: δ 1.92 (s, 6 H, Me), 7.15-7.64 (m, 60 H,
PPh3). 31P{1H} NMR (20 °C): δ 5-13 (v br, AgPPh3), 30.37 (s,
PdPPh3). 31P{1H} NMR (-60 °C): δ 8.52 [dd, J(31P109Ag) ) 470 Hz,
J(31P107Ag) ) 409 Hz], 25-36 (br).
6b. Yield: 138 mg, 92%. Anal. Calcd for C78H66AgClO6P4PtS2: C,
57.62; H, 4.09; S, 3.94. Found: C, 57.59 H, 4.15; S, 4.07. Mp: 146
°C (dec). ΛM (Ω-1 cm2 mol-1): 146. IR (cm-1): 1680 s, 1608 vs,
1091 s, 620 s, 518 s. 1H NMR: δ 1.92 (s, 6 H, Me), 7.13-7.43 (m, 60
H, PPh3). 31P{1H} NMR (20 °C): δ 6-13 (v br), 18.15 [s with 195Pt
satellites, J(31P195Pt) ) 3093 Hz]. 31P{1H} NMR (-60 °C): δ 8.52
[dd, J(31P109Ag) ) 472 Hz, J(31P107Ag) ) 410 Hz], 18.20 (br).
Results and Discussion
Synthesis. Complexes [M{η2-S2CdC{C(O)Me}2}L2] [M )
Pt, L2 ) 1,5-cyclooctadiene (cod) (1); L2 ) bpy, M ) Pd (2a),
Pt (2b), L ) PPh3, M ) Pd (3a), Pt (3b)] were obtained along
with TlCl by reacting equimolar amounts of [Tl2{S2CdC{C-
(O)Me}2}]30 and the corresponding [MCl2L2] complexes in
acetone (1) or chloroform (2) or dichloromethane (3) (see
Scheme 1). Replacement of the labile cod ligand in 1 with 2
equiv of PPh3 also leads to complex 3b, but both 3a and 3b
were best obtained through a third method: by reacting the
thallium derivative with the corresponding [MCl2(NCPh)2]
complex and PPh3 in a 1:1:2 molar ratio. The reaction in
dichloromethane between equimolar amounts of [Tl2{S2Cd
C{C(O)Me}2}] and [MCl2(NCPh)2] (M ) Pd, Pt) produced a
brownish suspension from which, after extraction with CH2Cl2
and filtration of the insoluble TlCl, a brown (Pd) or an orange
4a. Yield: 236 mg, 70%. Anal. Calcd for C20H36N2O4PdS4: C, 39.83;
H, 6.02; N, 4.64; S, 21.26. Found: C, 38.83; H, 5.18; N, 5.01; S, 19.96.
Mp: 227 °C (dec). ΛM (Ω-1 cm2 mol-1): 164. IR (cm-1): 1678 s,
1567 m, 946 s. 1H NMR: δ 2.22 (s, 12 H, Me), 3.48 (s, 24 H, NMe4).
Crystals of 4a were grown from acetone/diethyl ether.
4a′. Yield: 850 mg, 92%. Anal. Calcd for C84H72N2O4P4PdS4: C,
65.87; H, 4.74; N, 1.83; S, 8.36. Found: C, 62.08; H, 4.95; N, 1.70; S,
6.82. Mp: 208 °C (dec). ΛM (Ω-1 cm2 mol-1): 158. IR (cm-1): 1681
s, 1562 m, 1298 s, br. 1H NMR: δ 2.33 (s, 12 H, Me), 7.43-7.70 (m,
60 H, PPN).
4b. Yield: 339 mg, 92%. Anal. Calcd for C20H36N2O4PtS4: C, 34.72;
H, 5.24; N, 4.05; S, 18.53. Found: C, 37.12; H, 4.89; N, 4.13; S, 15.91.
Mp: 207 °C (dec). ΛM (Ω-1 cm2 mol-1): 161. IR (cm-1): 1672 s,
1562 m, 945 s. 1H NMR: δ 2.20 (s, 12 H, Me), 3.50 (s, 24 H, NMe4).

2054 Inorganic Chemistry, Vol. 40, No. 9, 2001
Vicente et al.
Scheme 1
Scheme 2
ratio produces TlCl together with the anionic complexes Q2-
[M{η2-S2CdC{C(O)Me}2}2] [M ) Pd, Q ) NMe4 (4a), Ph3Pd
NdPPh3 (PPN) (4a′), M ) Pt, Q ) NMe4 (4b)], which can be
isolated in good yield. Although their NMR spectra prove the
purity of all the three compounds and the crystal structure of
4a confirms the proposed structure, the elemental analysis results
found for carbon and sulfur of samples obtained after many
recrystallizations differ from the calculated values (see Experi-
mental Section), which could be due to combustion problems.
We have shown that 4a′ reacts with [PdCl2(NCPh)2] and PPh3
(1:1:2) to give 3a (80% yield) and PPNCl and also that A is an
intermediate species in this reaction (See Scheme 1). This proves
that the sulfur atoms of the 1,1-ethylenedithiolato ligand
coordinated to Pd in 4a′ retain enough coordinating ability to
replace not only the labile PhCN ligands in [PdCl2(NCPh)2]
but also the chloro ligands.
Similarly, complexes 1, 3a, and 3b can act as ligands toward
other metal centers. Thus, from their reactions with AgClO4
(1:1 in acetone), very high yields are obtained of the tetranuclear
complexes [{ML2}2Ag2{µ2,η2-(S,S′)-{S2CdC{C(O)Me}2}2}]-
(ClO4)2 [L ) PPh3, M ) Pd (5a), Pt (5b), L2 ) cod, M ) Pt
(5b′)] (see Scheme 2). Similarly, when 3a and 3b were reacted
with AgClO4 in the presence of PPh3 (1:1:2), the dinuclear
complexes [{M(PPh3)2}{Ag(PPh3)2}{µ2,η2-(S,S′)-{S2CdC{C-
(O)Me}2}}]ClO4 [M ) Pd (6a), Pt (6b)] result (see Scheme 2)
likely because the coordination of silver to two PPh3 ligands
avoids the dimerization process that leads to 5 in the absence
of PPh3.
(Pt) solid was precipitated by the addition of diethyl ether. We
assume these to be oligomeric species (A and B in Scheme 1)
of stoichiometry M{S2CdC{C(O)Me}2} based on their reactions
with 2 equiv of PPh3 to give complexes 3a and 3b. We have
not been able to obtain good elemental analyses of these species
even after many recrystallizations (Anal. Calcd for C12H12O4-
Pd2S4: C, 25.68; H, 2.16; S, 22.85. Found: C, 24.26; H, 2.02;
S, 22.01. Anal. Calcd for C12H12O4Pt2S4: C, 19.50; H, 1.64; S,
1
17.36. Found: C, 19.02; H, 1.60; S, 14.51). Because the H
NMR of spectra of A and B show many singlets in the 2.3-
2.7 ppm region, suggesting mixtures of oligomers, we do not
know if the wrong analysis results are due to combustion
problems or to the presence of some impurities. Resonances
due to the PhCN ligand are absent in these spectra. However,
from a synthetic point of view, these oligomeric species behave
as pure compounds because the yields of those reactions are
comparable to those obtained with other methods.
The reaction of [Tl2{S2CdC{C(O)Me}2}] with [MCl2(cod)]
(M ) Pd, Pt) reveals the greater lability of the cod ligand in
the palladium complex. In fact, whereas the reaction with the
platinum complex produces only substitution of the chloro
ligands to give 1, in the case of palladium the diolefin is also
displaced, yielding complex A. The same result is obtained when
starting from [PdCl2(norbornadiene)].
Crystal Structures of Complexes. The crystal structures of
complexes 3a (Figure 1), 3b (Figure 2), 4a (Figure 3), 5b‚Me2-
CO (Figure 4), and 5b‚2Et2O (Figure 4) have been determined
(see Tables 2-5). Complexes 3a and 3b are isostructural; both
show two phosphine ligands and the two sulfur atoms of a Z,E-
2,2-diacetyl-1,1-ethylenedithiolato ligand coordinated to pal-
ladium (3a) or platinum (3b), which are in slightly distorted
square planar environments [S(1), S(2), M, P(1), P(2) mean
The reaction in acetone of MCl2 (M ) Pd, Pt), [Tl2{S2Cd
C{C(O)Me}2}], and QCl (Q ) NMe4, PPN) in a 1:2:2 molar

1,1-Ethylenedithiolato Complexes
Inorganic Chemistry, Vol. 40, No. 9, 2001 2055
Figure 1. Structure of complex 3a in the crystal. Ellipsoids represent
50% probability levels. Phenyl H atoms omitted for clarity.
Figure 3. Structure of the anion of complex 4a in the crystal. Ellipsoids
represent 50% probability levels.
Figure 4. Structure of the cation of complex 5b‚2Et2O in the crystal.
Ellipsoids represent 50% probability levels. Solvent and H atoms are
omitted for clarity.
Figure 2. Structure of complex 3b in the crystal. Ellipsoids represent
50% probability levels. Phenyl H atoms are omitted for clarity.
any sulfur donor ligand43-46) that differ only in the metal (M
) Pd, Pt).
deviation: 0.07 (3a), 0.06 (3b) Å]. The C2CdCS2 skeleton of
the sulfur donor ligand is also planar [mean deviation: 0.01
(3a), 0.02 (3b) Å] with both acetyl groups rotated out of the
plane, one of them considerably [interplanar angle: 58° (3a),
59° (3b)], the other one only slightly [torsion angle: 12° (3a),
13° (3b)]. The S2MP2 and C2CdCS2 planes subtend an angle
of only 4.8° (3a) or 4.7° (3b). Both complexes display narrow
S(1)MS(2) [74.595(18) (3a), 74.46(5) (3b) Å] and S(1)C(1)S-
(2) [107.19(11)° (3a), 105.9(3)° (3b)] angles associated with
the small chelate bite. The Pd-P bond distances in 3a [2.3282-
(5), 2.3306(5) Å] are significantly longer than the Pt-P distances
in 3b [2.2909(14), 2.2920(16) Å], despite the marginally smaller
covalent radius of palladium compared to that of platinum. This
difference is reflected in the 31P NMR spectra of these
complexes (see below). A search of the Cambridge Structural
Database reveals longer Pd-P with respect to Pt-P bond
distances to be a common feature in pairs of complexes cis-
[MP2L2] (P ) any phosphorus donor ligand, L ) Cl35-42 or
The bond distances and angles in 3b are similar to those found
in [Pt{η2-S2CdCH{C(O)Ph}(PPh3)2],20 but compared to [Pt-
{η2-S2CdC(CN)CO2Et}(cod)],7 3b displays longer Pt-S bond
distances [2.3363(15), 2.3326(15) vs 2.299(2), 2.298(2) Å], in
agreement with the greater trans influence of phosphine
compared with olefin ligands47 and a shorter CdC bond distance
(37) Farrar, D. H.; Ferguson, G. J. Crystallogr. Spectrosc. Res. 1982, 12,
465.
(38) Steffen, W. L.; Palenik, G. J. Inorg. Chem. 1976, 15, 2432.
(39) Browning, C. S.; Farrar, D. H.; Frankel, D. C. Acta Crystallogr. 1992,
C48, 806.
(40) Hayashi; Konishi, T. M.; Kobori, Y.; Kumada, M.; Higuchi, T.;
Hirotsu, K. J. Am. Chem. Soc. 1984, 106, 158.
(41) Clemente, D. A.; Pilloni, G.; Corain, B.; Longato, B.; Tiripicchio
Camellini, M. Inorg. Chim. Acta 1986, 115, L9.
(42) Oberhauser, W.; Bachmann, C.; Stampfl, T.; Bruggeller, P. Inorg.
Chim. Acta 1997, 256, 223.
(43) Schierl, R.; Nagel, U.; Beck, W. Z. Naturforsch. B 1984, 39, 649.
(44) Buchweitz, J.; Gompper, R.; Polborn, K.; Robl, C.; Sailer, M.-T.;
Weigand, W. Chem. Ber. 1994, 127, 23.
(45) Guowei, W.; Hanqin, L. Acta Crystallogr. 1990, C465, 2457.
(46) Gouwei, W.; Ying, H.-Z.; Maochun, H.; Hanqin, L. Chin. J. Struct.
Chem. (Jiegou Huaxue) 1991, 10, 159.
(35) Kin-Chee, H.; McLaughlin, G. M.; McPartlin, M.; Robertson, G. B.
Acta Crystallogr., Sect. B 1982, 38, 421; Acta Crystallogr. 1982, B38,
421.
(36) Alcock, N. W.; Nelson, J. H. Acta Crystallogr. 1985, C41, 1748.

2056 Inorganic Chemistry, Vol. 40, No. 9, 2001
Vicente et al.
Table 5. Selected Bond Distances (Å) and Angles (deg) for
Table 2. Selected Bond Distances (Å) and Angles (deg) for
Complex 3a
Complex 5b
Pd-P(1)
Pd-P(2)
Pd-S(2)
Pd-S(1)
S(1)-C(1)
S(2)-C(1)
2.3306(5)
2.3282(5)
2.3286(5)
2.3294(5)
1.761(2)
1.746(2)
O(1)-C(3)
O(2)-C(5)
C(1)-C(2)
C(2)-C(3)
C(2)-C(5)
1.210(3)
1.223(3)
1.374(3)
1.495(3)
1.472(3)
5b‚2Et2O, monoclinic
5b‚Me2CO, triclinic
Pt-P(2)
2.2912(10)
2.2999(11)
2.3625(10)
2.3700(10)
3.1204(5)
2.4265(11)
2.4591(11)
3.1363(8)
1.791(4)
1.785(4)
1.214(6)
1.232(6)
1.348(5)
2.2989(9)
2.3065(8)
2.3588(8)
2.3589(8)
3.2387(3)
2.4116(9)
2.4337(9)
3.0588(6)
1.782(4)
1.787(3)
1.211(5)
1.222(4)
1.355(4)
1.510(5)
1.499(5)
Pt-P(1)
Pt-S(2)
Pt-S(1)
Pt-Ag
Ag-S(1)#1
Ag-S(2)
Ag-Ag#1
S(1)-C(1)
S(2)-C(1)
O(1)-C(3)
O(2)-C(5)
C(1)-C(2)
C(2)-C(5)
C(2)-C(3)
P(1)-Pd-P(2)
P(1)-PdS(2)
P(2)-Pd-S(1)
S(2)-PdS(1)
98.792(18) C(3)-C(2)-C(5) 118.05(19)
91.170(18) O(1)-C(3)-C(2) 120.0(2)
95.623(18) O(1)-C(3)-C(4) 120.4(2)
74.595(18) C(2)-C(3)-C(4) 119.5(2)
C(2)-C(1)-S(1) 126.01(16)
C(2)-C(1)-S(2) 126.79(16)
O(2)-C(5)-C(2) 122.3(2)
O(2)-C(5)-C(6) 119.2(2)
C(2)-C(5)-C(6) 118.4(2)
S(1)-C(1)-S(2)
107.19(11)
C(1)-C(2)-C(3) 120.7(2)
1.499(6)
1.514(6)
C(1)-C(2)-C(5) 121.26(19)
Table 3. Selected Bond Distances (Å) and Angles (deg) for
Complex 3b
P(1)-Pt-Ag
P(1)-Pt-S(2)
P(2)-Pt-Ag
P(2)-Pt-P(1)
P(2)-Pt-S(1)
S(1)-Pt-Ag
S(2)-Pt-Ag
S(2)-Pt-S(1)
S(2)-Ag-Pt
Pt-Ag-Ag#1
97.51(3)
88.79(4)
121.72(3)
100.92(4)
96.33(4)
80.70(3)
51.04(3)
74.98(4)
48.33(2)
71.321(15)
94.87(2)
93.81(3)
139.17(2)
99.79(3)
90.30(3)
82.19(2)
48.47(2)
74.97(3)
46.51(2)
65.823(10)
Pt-P(1)
Pt-P(2)
Pt-S(2)
Pt-S(1)
S(1)-C(1)
S(2)-C(1)
2.2909(14)
2.2920(16)
2.3326(15)
2.3363(15)
1.757(6)
O(1)-C(3)
O(2)-C(5)
C(1)-C(2)
C(2)-C(3)
C(2)-C(5)
1.223(7)
1.213(7)
1.349(7)
1.467(8)
1.491(8)
1.783(6)
P(1)-Pt-P(2)
98.33(6)
95.97(6)
91.36(5)
74.46(5)
127.5(5)
126.6(5)
105.9(3)
121.0(6)
120.7(6)
C(3)-C(2)-C(5)
O(1)-C(3)-C(2)
O(1)-C(3)-C(4)
C(2)-C(3)-C(4)
O(2)-C(5)-C(2)
O(2)-C(5)-C(6)
C(2)-C(5)-C(6)
118.2(6)
122.0(6)
120.3(6)
117.7(6)
119.9(6)
119.6(6)
120.4(6)
P(1)-Pt-S(2)
P(2)-Pt-S(1)
S(2)-Pt-S(1)
C(2)-C(1)-S(1)
C(2)-C(1)-S(2)
S(1)-C(1)-S(2)
C(1)-C(2)-C(3)
C(1)-C(2)-C(5)
angles [S(1)PdS(3), 74.69(6)°; S(2)PdS(4), 74.84(6)°] similar
to those found in 3. The different conformation of the ligands
in 4a with respect to the Z,E found in 3 affects neither their
planarity [S(2)S(4)C(1)C(2)C(4)C(5) and S(1)S(3)C(7)C(8)C-
(9)C(11) mean deviations: 0.04 and 0.03 Å, respectively] nor
the fact that in each ligand only one of the acetyl groups [C(2)C-
(5)O(1) and C(8)C(9)O(4)] deviates markedly from that plane
(torsion angles of 6.7° and 8.1°, respectively) while the other
[C(2)C(3)O(2) and C(8)C(11)O(3)] is nearly coplanar (torsion
angles of 4.4° and 2.7°, respectively).
Table 4. Selected Bond Distances (Å) and Angles (deg) for
Complex 4a
Pd-S(1)
2.315(2)
2.312(2)
2.323(2)
2.321(2)
1.736(7)
1.741(7)
1.745(7)
1.738(7)
1.382(9)
C(7)-C(8)
C(2)-C(3)
C(2)-C(5)
C(8)-C(9)
C(8)-C(11)
O(1)-C(5)
O(2)-C(3)
O(3)-C(11)
O(4)-C(9)
1.378(9)
1.427(10)
1.510(10)
1.522(9)
1.429(10)
1.215(9)
1.230(8)
1.256(9)
1.204(8)
Pd-S(2)
Complex 5b has been obtained in monoclinic (5b‚2Et2O) and
triclinic (5b‚Me2CO) crystal forms. Both exhibit crystallographic
inversion symmetry. The complex results from the coordination
to Ag(I) of both sulfur atoms of the metalloligand complex 3b,
and its crystal structures show tetranuclear Pt2M2 cations,
perchlorate anions, and solvent molecules. Upon coordination
to silver, only some of the main features of 3b are preserved,
such as the Z,E conformation of the 2,2-diacetyl-1,1-ethylene-
dithiolato ligand and the planarity of its C2CdCS2 skeleton
[mean deviations: 0.01 (5b‚2Et2O), 0.02 (5b‚Me2CO) Å].
However, compared to that of 3b, the structures of 5b show
some differences. Thus, in complex 5b the platinum environ-
ment deviates significantly from planarity; mean deviation for
the five atoms S(1), S(2), Pt, P(1), P(2) is 0.05 Å for the
monoclinic modifications and 0.13 Å for the triclinic one.
Although a smaller mean deviation is found in the monoclinic
modification of 5b, the Pt atom lies 0.13 Å out of the P2S2
plane (displaced toward the silver atom) and the P(1)-Pt-P(2)
plane is rotated by 20° (in the triclinic form 24°) with respect
to the plane of the C2CdCS2 skeleton of the ligand, thus
avoiding steric congestion. Coordination of 3b to silver causes
significant lengthening in the Pt-S bond distances, while in
general, only small variations are observed for S-C and CdC.
The bond angles in the platinum moiety are similar in complexes
3b and 5b, which in all cases display a narrow S(1)-Pt-S(2)
angle [74.46(5)-75.63(3)°] imposed by the chelating ligand.
The olefinic C(1) and C(2) atoms in 5b are in planar, distorted
trigonal environments, showing narrow S(1)-C(1)-S(2) angles
[105.9(3)-107.8(2)°]. The silver atoms in these complexes are
Pd-S(3)
Pd-S(4)
S(1)-C(7)
S(3)-C(7)
S(2)-C(1)
S(4)-C(1)
C(1)-C(2)
S(1)-Pd-S(2)
104.67(7) C(7)-C(8)-C(9)
105.81(7) C(11)-C(8)-C(9)
74.69(6) O(1)-C(5)-C(6)
74.84(6) O(1)-C(5)-C(2)
117.4(7)
113.8(6)
122.0(8)
120.5(8)
117.5(7)
118.7(7)
119.2(8)
122.1(8)
122.1(7)
120.9(7)
116.9(7)
118.4(7)
S(3)-Pd-S(4)
S(1)-Pd-S(3)
S(2)-Pd-S(4)
C(2)-C(1)-S(2)
S(4)-C(1)-S(2)
S(4)-C(1)-S(2)
C(8)-C(7)-S(1)
C(8)-C(7)-S(3)
S(1)-C(7)-S(3)
C(1)-C(2)-C(3)
C(1)-C(2)-C(5)
C(3)-C(2)-C(5)
122.3(6)
107.8(4)
107.8(4)
129.9(6)
122.0(6)
108.0(4)
129.9(8)
117.0(7)
113.1(6)
C(6)-C(5)-C(2)
O(2)-C(3)-C(2)
O(2)-C(3)-C(4)
C(2)-C(3)-C(4)
O(4)-C(9)-C(10)
O(4)-C(9)-C(8)
C(10)-C(9)-C(8)
O(3)-C(11)-C(8)
O(3)-C(11)-C(12) 118.1(7)
C(7)-C(8)-C(11) 128.8(7)
C(8)-C(11)-C(12) 123.5(7)
[1.349(7) vs 1.38(1) Å], suggesting stronger delocalization over
the π-electron system of the S2CdC(CN)CO2Et ligand.
The crystal structure of 4a shows NMe4 cations (disordered)
and [Pd{η2-S2CdC{C(O)Me}2}2]2- anions in which two E,E-
2,2-diacetyl-1,1-ethylenedithiolato ligands coordinate the pal-
ladium atom in a distorted square planar environment [S(1),
S(2), Pd, S(3), S(4) mean deviation: 0.002 Å] with narrow SPdS
(47) Purcell, K. F.; Kotz, J. C. Inorganic Chemistry; W. B. Saunders
Company: Philadelphia, 1977.

1,1-Ethylenedithiolato Complexes
Inorganic Chemistry, Vol. 40, No. 9, 2001 2057
Table 6. Dimensions of Possible Intermolecular C-H‚‚‚O
are stronger than P-Pd in the homologous complexes. This is
also supported by the shorter Pt-P bond distances found in the
crystal structure of 3b compared with Pd-P in the homologous
complex 3a.
Hydrogen Bondsa
compound
system
H‚‚‚O (Å) C-H‚‚‚O (deg)
3a
C(13)-H(13)‚‚‚O(1)
C(55)-H(55)‚‚‚O(2)
C(13)-H(13)‚‚‚O(1)
C(63)-H(63)‚‚‚O(2)
2.47
2.48
2.51
2.48
2.55
2.51
2.49
2.54
148
168
166
150
137
130
158
120
The spectra of complexes 6a and 6b show one broad
resonance (6a, 5-13; 6b, 6-13 ppm) due to the Ag(PPh3)2
fragment, suggesting that in solution an intermolecular inter-
change process of PPh3 occurs at room temperature; we have
previously observed this in other AgPPh3 complexes.48 When
the spectra are measured at low temperature (-60 °C), both
resonances are affected. The wide P-Ag resonance splits into
two doublets [6a, δ 8.52, J(31P109Ag) ) 470 Hz, J(31P107Ag) )
409 Hz; 6b, δ 8.52, J(31P109Ag) ) 472 Hz, J(31P107Ag) ) 410
Hz] as expected for the coupling of 31P with 107Ag and 109Ag.48
The measured coupling constants are in the range reported in
the literature for sp2-hybridized silver(I) complexes of the type
AgL2X (L ) monodentate arylphosphine).50 The resonance due
to the M(PPh3)2 moiety is a sharp singlet downfield-shifted for
the palladium complex (6a, 30.37 ppm) with respect to the
platinum analogue (6b, 18.15 ppm, 195Pt satellites, J ) 3093
Hz) as in the case of the 3a, 3b couple. However, at -60 °C
this resonance broadens significantly. This suggests that rapid
interchange of the Ag(PPh3)2 unit between both sulfur donor
atoms lead to the singlet resonance observed at room temper-
ature for the P nuclei of the M(PPh3)2 group and that the
coalescence temperature for this fluxional process is close to
-60 °C.
3b
5b‚Me2CO C(66)-H(66)‚‚‚O(1)
C(33)-H(33)‚‚‚O(2)
C(13-)H(13)‚‚‚O(6)
C(63)-H(63)‚‚‚O(12)
5b‚2Et2O
a The cutoff criterion is H‚‚‚O < 2.6 Å. Key to atom numbering:
the oxygen atoms O1 and O2 are those of the ethylenedithiolate ligand;
others are perchlorate oxygens.
in distorted linear environments [S-Ag-S, 168.32(4)°, 174.10-
(3)°] and display short numismophilic48 [Ag‚‚‚Ag, 3.1361(8),
3.0588(6) Å] and weak Pt‚‚‚Ag [3.1205(5), 3.2387(3) Å]
contacts. In both structures of 5b the coordination plane of
platinum is perpendicular (within 7°) to the S4M2 plane.
The structures of 3a, 3b, and 5b display C-H‚‚‚O contacts
that might reasonably be interpreted as hydrogen bonds;
corresponding dimensions (excluding those involving disordered
groups) are presented in Table 6.
NMR Spectra. The 1H NMR spectra of complexes 1-6 show
a unique resonance in the range 1.92-2.36 ppm. The equiva-
lence of the methyl groups could be associated with an E,E
conformation of the 1,1-ethylenedithiolato ligands in solution,
as confirmed in the solid state for 4a, or, if the ligands adopt
the E,Z conformation (see crystal structures of 3a, 3b, and 5b),
with free rotation of the acetyl groups around the C-C bond in
solution. This is confirmed for 1, 2a, and 3a, and 3b by their
13C{1H} NMR spectra, which show unique resonances for each
of the nuclei CH3 (30.8-32.1 ppm), CdCS2 (136.8-139.8
ppm), CdCS2 (175.2-190.1 ppm), and C(O) (196.9-198.1
ppm). The 31P{1H} NMR spectra of complexes 3a and 5a show
one singlet resonance at 29.71 and 26.0 ppm, respectively,
indicating the equivalence of both phosphine ligands. In the
spectra of their platinum analogues 3b and 5b, this resonance
shows 195Pt satellites [J(31P195Pt) of 3041 and 3068 Hz,
respectively] and is appreciably highfield-shifted (3b, 19.15
ppm; 5b, 18.78 ppm). It is widely accepted that for 13C and
heavier nuclei (31P) the chemical shifts depend on the para-
magnetic contribution (σp) to the total screening constant (σ).49
σp is negative, and its absolute value |σp| varies inversely with
the energy difference (∆E) between the occupied and unoc-
cupied molecular orbitals in which the atom is involved. For
stronger bonds one expects larger ∆E, smaller |σp|, larger σ,
and thus lower δ values. Accordingly, the lower 31P chemical
shifts observed in the P-Pt complexes suggest that P-Pt bonds
IR Spectra. The IR spectra, measured in the solid state, show
several bands (see Experimental Section) in the 1690-1450
cm-1 region that cannot be unequivocally assigned to ν(CdO)
or ν(CdC) stretching modes because these have proved to be
coupled to other carbonyl-containing push-pull ethylenes.51 The
bands at higher frequencies (over 1600 cm-1) largely reflect
the strength of the CdO bond,51 and their lowering in energy
could be attributed to conjugation within the S2CdC{C(O)Me}2
ligand or to coordination of the carbonyl oxygen atoms to a
metal center. The spectra of complexes 4 show bands due to
the corresponding cations at around 950 (4a, 4b: NMe4) or 1300
and 525 (4a′: PPN) cm-1, while those of 5 and 6 show intense
perchlorate bands at around 1100 and 620 cm-1
.
Acknowledgment. We thank Direccio´n General de Inves-
tigacio´n Cient´ıfica y Te´cnica (Grant PB97-1047) (J.V.) and the
Fonds der Chemischen Industrie (P.G.J.) for financial support.
S.H. thanks the Ministerio de Educacio´n y Cultura (Spain) for
a grant.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of complexes 3a, 3b,
4a, 5b‚Me2CO and 5b‚2Et2O. This material is available free of charge
via the Internet at http://pubs.acs.org.
(48) Vicente, J.; Chicote, M. T.; Lagunas, M. C. Inorg. Chem. 1993, 32,
3748.
IC000996E
(49) Friebolin, H. Ein- und zweidimensionale NMR-Spektroskopie (One-
and Two-Dimensional NMR Spectroscopy), 2nd ed.; VCH: Weinheim,
Germany, 1992; p 43.
(50) Muetterties, L.; Alegranti, C. W. J. Am. Chem. Soc. 1972, 94, 6386.
(51) Smith, D.; Taylor, P. J. J. Chem. Soc., Perkin Trans 2 1979, 1376.