CS2 insertion into a gold-carbon bond. First syntheses and characterization of 2,2-diacetylethylene-1,1-dithiolato complexes. Crystal structure of [N(PPh3)2][Au{η2-S 2C=C(COMe)2}2</sub

Article abstract of DOI:10.1039/a705052f

The reaction of [N(PPh₃)₂][Au(acac)₂] (acac = acetylacetonate) with CS₂ gives [N(PPh₃)₂]₂[Au₂{μ ²:η²-S₂C=C(COMe)₂}₂

Full text of DOI:10.1039/a705052f

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CS2 insertion into a gold–carbon bond. First syntheses and characterization of
2,2-diacetylethylene-1,1-dithiolato complexes. Crystal structure of
2
[N(PPh3)2][Au{h -S2CNC(COMe)2}2]†
Jose´ Vicente,*a‡ Mar´ıa Teresa Chicote,*a Pablo Gonza´lez-Herreroa and Peter G. Jones*b§
a Grupo de Qu´ımica Organometa´lica,¶ Departamento de Qu´ımica Inorga´nica, Facultad de Qu´ımica, Universidad de Murcia,
Aptdo. 4021, E-30071 Murcia, Spain
b Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Braunschweig, Postfach 3329, 38023 Braunschweig,
Germany
The reaction of [N(PPh3)2][Au(acac)2] (acac = acetylaceto-
complexes, respectively.7 However, in the case of gold these
reactions have scarcely been studied and thus only two other
CS2 insertion reactions have been described so far, namely
2
2
nate)
with
CS2
gives
[N(PPh3)2]2[Au2{m :h -
S2CNC(COMe)2}2], which reacts with PhICl2 to give
2
1
[N(PPh3)2][Au{h -S2CNC(COMe)2}2], for which the crystal
those into the Au–C bond in [Au{h -C5Me5)(PR3)] complexes
1
structure is determined; these are the first characterized
2,2-diacetylethylene-1,1-dithiolato complexes of any ele-
ment.
to
give
dithiocarboxylato
complexes
[Au{h -
S2CC5Me5)(PR3)n] (R = Ph, n = 2; R = Pri, n = 3)8 or into an
Au–Cl bond of [Au2Cl6] to give the chlorodithioformate
2
complex [AuCl2(h -S2CCl)].9 We have ourselves described the
Interest in gold complexes containing S-bonded ligands stems
from their potential application in the glass and ceramic
industries1 and, more importantly, in medicine (chrysothe-
rapy).2 Thiolatogold(i) complexes such as the commercial
Myocrisin, Allochrysine, Solganol, or Auranofin, are among the
most efficient antiarthritic drugs.2 In addition, Solganol and
Auranofin show in vitro inhibitory effects on Human Im-
munodeficiency Virus 1,3 high cytotoxicity to tumor cells4 and
activity against i.p. P388 leukaemia.5
insertion of CS2 into an Au–S (or S–H) bond in
[N(PPh3)2][Au(SH)2] to produce the first trithiocarbonatogold
complex.10
In
the
reaction
of
CS2
with
[Au(C6F5)(PPh2CHPPh2Me)] the complex [AuIII{PPh2C(PPh2-
Me)CS2}2][AuI(C6F5)2], resulting from a carbon–carbon cou-
pling reaction, is obtained.11
The reaction of methylene active compounds with CS2 and
LiNR2, NaH,12 or K2CO3,13 led to the synthesis of the
corresponding 2,2-disubstituted ethylene-1,1-dithiolate salts,
which were treated in situ with MeI to give ketene dithioacetals.
In this context acetylacetone has been used to prepare
We have found that CS2 reacts with [N(PPh3)2][Au(acac)2]6
2
2
to give [N(PPh3)2]2[Au2{m :h -S2CNC(COMe)2}2] 1 (Scheme
1). As far as we are aware, this is the first fully characterized
2,2-diacetylethylene-1,1-dithiolato complex of any element.
In the absence of any mechanistic data, we assume that the
CS2 inserts into one of the gold–carbon bonds to produce a
dithiocarboxylato complex a (see Scheme 1), likely to be in
tautomeric equilibrium with the ethylene-1,1-dithiolato form b,
the remaining acac ligand being responsible for intermolecular
deprotonation and subsequent dimerization to give 1 with
concomitant formation of acetylacetone.
the
2-acetyl-2-oxopropylidene-S,S-acetal
[(MeS)2CNC-
{C(O)Me}2].13–15 Our synthetic method is, therefore, un-
precedented. Ketene dithioacetals are of current interest because
the double carbon–carbon bond they present is amenable to both
nucleophilic and electrophilic attack.14 Indeed, they are very
versatile starting materials for the synthesis of a wide variety of
fused heterocycles,13,16 polysubstituted pyridines,17 pyra-
zoles,18 etc. On the other hand, the interest in ketene
dithioacetals with electron-withdrawing substituents stems
from some of their physical properties as push–pull polarized
ethylenes. Thus, the effect of chiral substituents or hydrogen
bonding on second-order non-linearity,19 the free energy of
activation for rotation around the carbon–carbon double
Insertion reactions of CS2 into transition-metal–H, –C, –N,
–P, –S, or –Cl bonds are known to produce dithioformiato,
dithiocarboxylato,
dithiocarbamato,
phosphinodithiocar-
boxylato, trithio- or perthio-carbonato, or chlorodithioformiato
2 Q[Au(acac)2]
i
acac Au
S
S
C(O)Me
CH
C(O)Me
acac Au
S
C(O)Me
C(O)Me
2 Q
C
C C
2 Q
HS
a
b
ii
Me(O)C
S
S
Au
S
C(O)Me
C
C
C C
Q2
Me(O)C
Au
S
C(O)Me
1
iii
Me(O)C
Me(O)C
S
S
C(O)Me
C(O)Me
Au
C
C
C C
Q
S
S
2
Scheme 1 Q = [N(PPh3)2], acac = acetylacetonate. Reagents and conditions: i, CS2 (excess) in acetone, 1 h, room temp; ii, 22 Hacac; iii, + Cl2IPh 2 PhI
2 Q[AuCl2], CH2Cl2, 45 min, room temp.
Chem. Commun., 1997
2047

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We thank DGICYT (PB92-0982C) and the Fonds der
Chemischen Industrie for financial support. P. G.-H. is grateful
to Ministerio de Educacio´n y Cultura for a Grant.
O(2)
S(1A)
Footnotes and References
C(6)
S(2)
C(5)
† Dedicated to Professor Pascual Royo on the occasion of his 60th
birthday.
‡ E-mail: jvs@fcu.um.es
C(4)
Au(1)
C(1)
§ E-mail: p.jones@tu-bs.de
C(3)
¶ WWW: http://www.scc.um.es/gi/gqo/
∑ Crystal data for complex 2: C48H42AuNO4P2S4, triclinic, space group P1,
S(1)
¯
O(1)
C(2)
T = 143 K, a = 10.729(3), b = 11.853(3), c = 18.076(4) Å, a = 83.13(2),
b = 81.62(2), g = 79.75(2)°, U = 2227.6(10) Å3, Z = 2, l(Mo-
Ka) = 0.71073 Å, m = 3.61 mm21, Dc = 1.616 Mg m23. Data collection:
Yellow prism 0.55 3 0.40 3 0.30 mm, Stoe STADI-4 diffractometer, 9522
intensities of which 7867 independent, 2qmax 50°, absorption corrections
based on y-scans with transmissions 0.776–0.933. Structure solution and
refinement: heavy-atom method, refined anisotropically on F2 (program
SHELXL-93, G.M. Sheldrick, University of Go¨ttingen). H atoms with
riding model or as rigid methyl groups. In the C(NO)Me groups of the
second anion, the slightly short C–C and long CNO bonds and the difficulty
in locating methyl H may indicate some disorder. Final wR(F2) 0.0742,
Fig. 1 Structure of one of the two independent anions of 2. Selected bond
lengths (Å) and angles (°): Au(1)–S(1) 2.3234(13), 2.3375(13), Au(1)–S(2)
2.3479(12), 2.3217(12), C(1)–S(1) 1.758(4), 1.748(4), C(1)–S(2) 1.744(4),
1.755(4), C(1)–C(4) 1.353(6), 1.365(6); S(1)–Au(1)–S(2) 74.16(4),
74.46(4), S(2)–Au(1)–S(1A) 105.84(4), 105.54(4), S(1)–C(1)–S(2)
107.0(2), 107.2(2), S(1)–C(1)–C(4) 125.8(3), 126.1(3), S(2)–C(1)–C(4)
127.2(3), 126.8(4).
bond,15,20 or the influence of the double bond twisting on the
position of the IR nCNC stretching band21 or on the photoioniza-
tion energy22 have been studied. Our synthesis opens a new
access for such studies. The only 2,2-diacetylethylene-1,1-di-
thiolato complexes (of MnII, CoII, NiII, CuII and ZnII) mentioned
in the literature were prepared from the corresponding sodium
salt of the ligand and their composition was only established by
elemental analysis, while amperometric and potentiometric
titrations were unsuccessful.23
R(F) 0.0296, 547 parameters, 464 restraints, S = 1.09, max Dr 1.4 e Å23
.
CCDC 182/591.
1 A. N. Papazian, Gold Bull., 1982, 15, 81.
2 A. Lorber and T. M. Simon, Gold Bull., 1979, 12, 149; K. C. Dash and
H. Schmidbaur, Metal Ions in Biological Systems, ed. H. Sigel, Marcel
Dekker, New York, 1982; P. J. Sadler, Adv. Inorg. Chem., 1991, 36, 1.
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192, 631.
4 T. M. Simon, D. H. Kunishima, D. H. Vibert and A. Lorber, Cancer
Res., 1981, 41, 94.
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and S. T. Crooke, Cancer Res., 1985, 45, 32.
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10 J. Vicente, M. T. Chicote, P. Gonza´lez-Herrero and P. G. Jones,
J. Chem. Soc. Chem. Commun., 1995, 745.
Many dinuclear gold(i) complexes are known to undergo
oxidative addition reactions with halogens, pseudohalogens or
alkyl halides to give gold(ii) complexes containing a gold–gold
bond.24 However, when complex 1 is treated with an equimolar
amount of Cl2IPh in dichloromethane a disproportionation
reaction takes place, giving [N(PPh3)2][AuCl2] along with the
2
gold(iii) complex [N(PPh3)2][Au{h -S2CNC(COMe)2}2] 2. The
same behaviour has previously been observed for other
dithiolato,25 dialkyldithiocarbamato,26 or trithiocarbonato27
gold(i) complexes.
The isolated complexes 1 and 2 have been fully characterized
by C, H, N, S analyses, IR spectroscopy and 1H and 13C NMR.
The X-ray crystal structure of complex 2 (Fig. 1),∑ shows it to
crystallize with two independent half-anions and one
11 M. Bardaj´ı, M. C. Gimeno, P. G. Jones, A. Laguna, M. Laguna,
F. Mercha´n and I. Romeo, Organometallics, 1997, 16, 1083.
12 Z.-T. Huang and X. Shi, Synthesis, 1990, 162.
13 A. K. El-Shafei, A. M. M. El-Saghier and E. A. Ahmed, Synthesis, 1994,
152.
[N(PPh3)2] cation in the asymmetric unit. Both anions show
2
almost
identical
inversion-symmetric
[Au{h -
S2CNC(COMe)2}2] E,Z-conformations. The gold atoms are in
distorted square-planar environments, the angles around gold
differing from the ideal value of 90° because of the small bite of
the dithiolate ligand [S(1)–Au(1)–S(2) 74.16(4), 74.46(4)°;
S(1)–Au(1)–S(2A) 105.84(4), 105.54(4)°, respectively]. The
Au(1), S(1), S(2), C(1) and C(2) atoms are coplanar (mean
deviation 0.054, 0.044 Å), with both acetyl groups twisted out
of this plane, one of them considerably (torsion angle 55, 48°),
the other one slightly (torsion angle 9, 13°, respectively). The
C(1)–C(4) bond distances [1.353(6), 1.365(4) Å] lie in the range
expected for C(sp2)NC(sp2) double bonds (1.294–1.392)28 and
are similar to that found in the closely related ketene S,S-
dithioacetal (MeS)2CNC{C(O)Me}2 (1.351 Å) which shows a
twisted (torsion angle 14°) E,E-conformation.29
14 D. Villemin and A. B. Alloum, Synthesis, 1991, 301.
15 J. Sandstro¨m and I. Wennerbeck, Acta Chem. Scand., 1970, 24, 1191.
16 L.-B. Wang and Z.-T. Huang, Synth. Commun., 1996, 26, 459;
Z.-T. Huang and X. Shi, Chem. Ber., 1990, 123, 541.
17 F. A. Abu-Shanab, M. H. Elnagdi, F. M. Ali and B. J. Wakefield,
J. Chem. Soc., Perkin Trans. 1, 1994, 1449.
18 E. C. Taylor and P. W. Ronald, Heterocycles, 1977, 8, 243.
19 K. Mohanalingam, M. Nethaji and P. K. Das, J. Mol. Struct., 1996, 378,
177.
20 J. Sandstro¨m and U. Sjo¨strand, Tetrahedron, 1978, 34, 3305.
21 D. Smith and P. J. Taylor, J. Chem. Soc., Perkin Trans. 2, 1979,
1376.
22 F. P. Colonna, G. DiStefano, J. Sandstro¨m and U. Sjo¨strand, J. Chem.
Soc., Perkin Trans. 2, 1978, 279.
23 W. U. Malik, R. Bembi and V. K. Bharddwaj, J. Indian Chem. Soc.,
1984, 65, 379.
Apart from bands due to the cation, the solid-state IR
spectrum of 1 shows two strong n(CNO) bands at 1698 and 1678
cm21 and a strong n(CNC) band at 1580 cm21, while the n(AuS)
band(s) cannot be assigned unequivocally because of the
presence of bands from the [N(PPh3)2] cation in the 400–300
cm21 region. The position of the n(CNO) band suggest that
conjugation plays at best a marginal role.29 The IR spectrum of
2 shows two strong n(CNO) bands at 1664 and 1636 cm21 and
a medium n(AuS) band at 370 cm21. The frequency of the
n(CNC) band is expected to decrease because of conjugation
with one of the acetyl groups and cannot be unequivocally
assigned.
24 J. P. Fackler Jr., Polyhedron, 1997, 16, 1.
25 M. N. I. Khan, S. Wang and J. P. Fackler Jr., Inorg. Chem., 1989, 28,
3579.
26 D. C. Calabro, B. A. Harrison, G. T. Palmer, M. K. Moguel,
R. L. Rebbert and J. L. Burmeister, Inorg. Chem., 1981, 20, 4311.
27 J. Vicente, M. T. Chicote, P. Gonza´lez-Herrero and P. G. Jones,
unpublished work.
28 F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen and
R. Taylor, J. Chem. Soc., Perkin Trans. 2, 1987, S1.
29 A. J. Jarvis and P. J. Taylor, J. Chem. Soc., Perkin Trans. 2, 1978,
972.
Received in Cambridge, UK, 15th July 1997; 7/05052F
2048
Chem. Commun., 1997