Novel palladium and platinum carbene-complexes containing dithiocarbonate ligand [M(PPh3) {η2(S,S)-S2CO]-{C(SR)(NMe2)}] formed via alkyl migration of O-alkyldithiocarbonate to thiocarbamoyl ligand

Article abstract of DOI:10.1039/b305374a

The first example of alkyl migration of O-alkyldithiocarbonate to thiocarbamoyl ligand results in carbene-complexes [M(PPh₃){η²(S,S)-S₂CO] {C(SR)(NMe₂)}] (M = Pd, Pt; R = Me, Et) from the reactions of [M(η²

Full text of DOI:10.1039/b305374a

View Article Online / Journal Homepage / Table of Contents for this issue
Novel palladium and platinum carbene-complexes containing
dithiocarbonate ligand [M(PPh3){ꢀ2(S,S )-S2CO]{C(SR)(NMe2)}]
formed via alkyl migration of O-alkyldithiocarbonate to
thiocarbamoyl ligand†
Kuang-Hway Yih,*a Gene-Hsiang Leeb and Yu Wangc
a Department of Applied Cosmetology, Hungkuang University, Shalu, Taichung, Taiwan 433,
Republic of China
b Instrumentation Center, College of Science, National Taiwan University, Taiwan,
Republic of China
c Department of Chemistry, National Taiwan University, Taiwan 106, Republic of China
Received 13th May 2003, Accepted 18th June 2003
First published as an Advance Article on the web 24th June 2003
The first example of alkyl migration of O-alkyldithio-
carbonate to thiocarbamoyl ligand results in carbene-
complexes [M(PPh3){ꢀ2(S,S)-S2CO]{C(SR)(NMe2)}] (M ؍
Pd, Pt; R ؍ Me, Et) from the reactions of [M(ꢀ2-SCNMe2)-
(PPh3)2][PF6] with KS2COR in MeOH.
4, one resonance at δ 2.88 and three resonances at δ 1.20 and
3.45, 4.03 and the corresponding 13C{1H} NMR signals at
δ 21.2, and at δ 13.4, 33.4 are attributed to the thiomethylene8
and the thioethylene8 groups respectively. From the above
descriptions, it is clear that the alkyl group of the O-alkyldithio-
carbonate ligand migrate to the thiocarbamoyl ligand forming
dithiocarbonate palladium-carbene complexes. The π inter-
action between the carbene carbon and SR or NMe2 and the
higher chelate ability of the dithiocarbonate ligand than the
O-alkyldithiocarbonate ligand are two important factors in
stabilizing the carbene-complexes.
The activation of heteroallenes by transition metal complexes
is a topic of much activity.1 Formation of dithiocarbonate,
S2CO2Ϫ, metal complexes from the reactions of metal carbonyl
sulfide complexes with COS,2 metal carbon disulfide complexes
with dioxygen,3 dealkylation,4 iodide abstraction,5 and
hydrolysis6 of O-alkyldithiocarbonate metal complexes have
been reported. No alkyl migration process has been reported.
As an extension of our investigation on the thio-metal and
thiocarbamoyl palladium complexes,7 herein, we report the
unprecedented alkyl migration from the O-alkyldithiocarbonate
ligand to thiocarbamoyl ligand in palladium and platinum
complexes and crystal structure of the dithiocarbonate
palladium carbene-complex.
The aforementioned complex 3 has been studied by X-ray
diffraction.‡ An ORTEP plot of 3 is shown in Fig. 1. Crystals
of 3 were obtained from diffusion of n-hexane into dichloro-
methane. In complex 3, the palladium atom has a distorted
square planar geometry. The palladium atom is displaced by
0.0396 Å from the least-squares plane. The distortion is mainly
due to the short bite of the S2COϪ2 ligand, in which the S(1)–
Pd–S(2) angle is 76.01(3)Њ. The carbene carbon and the three
substitutents Pd, S, and N are coplanar to within 0.030 Å,
and the bond angles about C(2) (126.7, 113.5, and 119.8Њ)
clearly show the sp2 character of the carbon. The Pd–C(2)
bond distance, 2.043(4) Å, is longer than other PdII–carbon-
(carbonyl) distances,9 and similar to those of Pd–C(carbene)
distances.9 Within the carbene, C(SMe)(NMe2), ligand itself,
the geometry is consistent with significant partial double bond
character in the S(3)–C(2) and C(2)–N(1) bonds. Thus, the
S(3)–C(2) bond distance (1.731(4) Å) is comparable to the C–S
double bond in ethylenethiourea although it is longer than
those in free CS2 (1.554 Å). The C(2)–N(1) bond distance
(1.308(4) Å) is typical for a C–N bond having partial double
bond character and are certainly much shorter than the normal
C–N (1.47 Å) single bond. This implies pπ–pπ overlap, involving
the empty p-orbital of the C(2) atom. The Pd–S(1) and Pd–S(2)
bond distances of 2.3306(9) Å and 2.3250(9) Å are within the
normal Pd–S length range (2.23 ∼ 2.32 Å).10 The Pd–S(1) bond
The respective reactions of [Pd(η2-SCNMe2)(PPh3)2][PF6] 1
and MeOCS2K 2 or EtOCS2K in methanol at room tem-
perature yields the air-stable and orange–yellow complexes
[Pd(PPh3){η2(S,S)-S2CO]{C(SR)(NMe2)}] (R = Me, 3; Et, 4)
with 90 and 75% isolation yields (Scheme 1). Complexes 3 and 4
are isolated by recrystallization from hexane–CH2Cl2. The
spectroscopic‡ and analytical data of 3 and 4 were obtained. In
the FAB mass spectra, base peaks with the typical Pd isotope
distribution are in agreement with the [M]ϩ molecular masses
of 3 and 4. The IR spectra of 3 and 4 show the C᎐O stretching
᎐
band of the co-ordinated carbonate at 1675, 1603 and at 1681,
1605 cmϪ1, respectively, which are indicative of a chelate
dithiocarbonate ligand.2,3,5,6 In the 1H NMR spectrum of 3 and
† Electronic supplementary information (ESI) available: 1H and
13C{1H} NMR spectra of 3 and the 1H NMR spectrum of the mixtures
of 4 and 5. See http://www.rsc.org/suppdata/dt/b3/b305374a/
Scheme 1 Reagents and conditions: i, ROCS2K, MeOH, r.t., 5 min, R = Me, 90%; Et, 75%. ii, EtOCS2K, MeOH, r.t., 5 min.
D a l t o n T r a n s . , 2 0 0 3 , 2 8 1 0 – 2 8 1 2
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
2810

View Article Online
1
νCO/cmϪ1: 1675(vs), 1603(vs), νasCS: 832(m). H NMR: δ 2.88 (s, 3H,
SCH3), 2.96, 3.52 (s, 6H, 2NCH3), 7.30–7.57 (m, 15H, Ph). 31P{1H}
NMR: δ 28.0 (PPh3). 13C{1H} NMR: δ 21.2 (s, SCH3), 43.6, 52.0 (s,
NCH3), 128.2–134.2 (m, C of Ph), 199.0 (s, S2CO), 247.9 (d, NCSMe,
JP–C = 14.6). MS (FAB, NBA, m/z): 564 (Mϩ). Anal. Calcd. for
C23H24NOPS3Pd: C, 48.98; H, 4.30; N, 2.48%. Found: C, 49.85; H, 4.56;
N, 2.38. 4: IR (KBr) νCO/cmϪ1: 1681(vs), 1605(vs), νasCS: 832(m).
1H NMR: δ 1.20 (t, 3H, SCH2CH3, JH–H = 7.5), 2.89, 3.54 (s, 6H,
2NCH3), 3.45, 4.03 (m, 2H, SCH2), 7.40–7.57 (m, 15H, Ph). 31P{1H}
NMR: δ 28.0 (PPh3). 13C{1H} NMR: δ 13.4 (s, SCH2CH3), 33.4, (s,
SCH2), 43.6, 52.2 (s, NCH3), 128.4–134.0 (m, C of Ph), 199.1 (s, S2CO),
246.7 (d, NCSEt, JP–C = 15.2). MS (FAB, NBA, m/z): 578 (Mϩ). Anal.
Calcd. for C24H26NOPS3Pd: C, 49.87; H, 4.53; N, 2.42%. Found: C,
50.15; H, 4.38; N, 2.28.
Crystal data for (2)2ؒCH3CN: C6H9K2NO2S4, M = 333.58, mono-
clinic, space group P21/n, a = 9.91767(7) Å, b = 10.3027(8) Å, c =
14.3530(11) Å, β = 99.660(2)Њ, V = 1445.77(19) Å3, Z = 4, Dcalcd = 1.533 g
cmϪ3, µ = 1.214 mmϪl, independent reflections 3318, θrange = 2.32–27.50Њ.
Total number of parameters: 136. R = 0.028, Rw = 0.067; GOF = 1.038,
Mo Kα radiation; λ = 0.71073 Å; T = 150(1) K; ∆F = 0.474, Ϫ0.190 e
Å3. Crystal data for 3: C23H24NOPPdS3, M = 563.98, monoclinic, space
group P21/c, a = 16.3638(2) Å, b = 9.3374(1) Å, c = 15.7117(2) Å, β =
98.2957(6)Њ, V = 2375.56(5) Å3, Z = 4, Dcalcd = 1.577 g cmϪ3, µ = 1.128
mmϪl, independent reflections 5458, θrange = 1.26–27.50Њ. Total number
of parameters: 272. R = 0.039, Rw = 0.090; GOF = 1.119, Mo Kα
radiation; λ = 0.71073 Å; T = 150(1) K; ∆F = 0.813, Ϫ0.728 e Å3.
Absorption corrections of 2 and 3 have been carried out. The two
structures were solved by Patterson synthesis and then refined via
standard least-squares and difference Fourier techniques. Non-
hydrogen atoms were refined by using anisotropic thermal parameters.
CCDC reference numbers 210481 and 210482. See http://www.rsc.org/
suppdata/dt/b3/b305374a/ for crystallographic data in CIF or other
electronic format.
Fig. 1 ORTEP drawing with 50% thermal ellipsoids and atom-
numbering scheme for the complex [Pd(PPh3){η2(S,S)-S2CO}{C(SMe)-
(NMe2)}] 3. Selected bond distances (Å) and angles (Њ) are as follows:
Pd–C(2) 2.043(4), Pd–S(1) 2.3306(9), Pd–S(2) 2.3250(9), Pd–P(1)
2.2889(9), C(1)–O(1) 1.207(4), C(2)–S(3) 1.731(4), C(3)–S(3) 1.808(5),
C(2)–N(1) 1.308(5); S(2)–Pd–P(1) 171.56(3), S(1)–Pd–C(2) 170.61(10),
S(2)–C(1)–S(1) 108.0(2), N(1)–C(2)–Pd 126.7(3), C(5)–N(1)–C(4)
113.2(3).
5: IR (KBr) νCS/cmϪ1: 1436(m). 1H NMR: δ 1.40 (t, 3H, OCH2CH3,
3JH–H = 7.0), 2.95, 3.30 (s, 6H, NCH3), 4.55 (m, 2H, OCH2CH3), 7.37–
7.62 (m, 15H, Ph). 31P{1H} NMR: δ 24.8 (br, PPh3). 13C{1H} NMR:
δ 13.8 (s, OCH2CH3), 38.9, 40.8 (s, NCH3), 67.8, 68.0 (s, OCH2CH3),
128.3–134.2 (m, Ph), 210.0 (s, OCS2), 233.2 (s, NCS). MS (FAB, NBA,
distance is longer than the Pd–S(2) bond distance due to the
high trans influence of carbene ligand than PPh3 ligand. The
bond distances within the dithiocarbonate ligand, S–C(av),
1.773(4) Å, and C(1)–O(1), 1.207(4) Å, fall in the range
of values found for other dithiocarbonate complexes, and are
indicative of an overall electronic delocalization within the
S2CO group.2 The formation of an N, S-heteroatom carbene-
complex from the intramolecular alkyl-thiocarbamoyl coupling
is the first example in the literature.
1
m/z): 578 (Mϩ). 6: IR (KBr) νCO/cmϪ1: 1683(vs), 1610(vs). H NMR:
δ 2.82 (s, 3H, SCH3), 2.93, 3.49 (s, 6H, 2NCH3), 7.28–7.76 (m, 15H, Ph).
31P{1H} NMR: δ 15.4 (t, PPh3, JPt–P = 1662.3). 13C{1H} NMR: δ 21.8 (t,
SCH3, JPt–C = 34.5), 43.2, 51.2 (t, NCH3, JPt–C = 17.5, 30.8), 128.1–137.2
(m, C of Ph), 195.5 (s, S2CO), 229.8 (d, NCSMe, JP–C = 9.5). MS (FAB,
NBA, m/z): 653 (Mϩ). Anal. Calcd. for C23H24NOPS3Pt: C, 42.32; H,
3.71; N, 2.15%. Found: C, 42.48; H, 3.80; N, 2.01. 7: IR (KBr) νCO/
cmϪ1: 1680(vs), 1612(vs). 1H NMR: δ 1.43 (t, 3H, SCH2CH3, JH–H
=
7.1), 2.94, 3.21 (s, 6H, 2NCH3), 4.55 (q, 2H, SCH2, JH–H = 7.1), 7.37–
7.86 (m, 15H, Ph). 31P{1H} NMR: δ 28.0 (t, PPh3, JPt–P = 1616). 13C{1H}
NMR: δ 13.7 (t, SCH2CH3, JPt–C = 47.1), 39.8 (t, SCH2, JPt–C = 17.4),
43.8, 51.8 (t, NCH3, JPt–C = 17.4, 32.4), 128.2–134.4 (m, C of Ph), 194.4
(s, S2CO), 226.5 (d, NCSEt, JP–C = 9.2). MS (FAB, NBA, m/z): 667
(Mϩ). Anal. Calcd. for C24H26NOPS3Pt: C, 43.23; H, 3.93; N, 2.10%.
Found: C, 43.35; H, 4.08; N, 2.02.
In an attempt to get information about the alkyl migration,
complex [Pd(η1-CSNMe2)(PPh3)2(Cl)]7 was used to react with
EtOCS2K in MeOH at room temperature for 5 min to form
complexes [Pd(PPh3){η2(S,S)-S2COEt]{η1-CS(NMe2)}] 5‡
and 4 with a 10 : 1 ratio from the integration of 31P{1H} NMR
spectrum. In the solution state, complex [Pd(PPh3){η2(S,S)-
S2COEt]{η1-CS(NMe2)}] 5 ethyl migration slowly gives 4
during 2 h. To test the generality of these reactions, we have
studied the platinum system. Interestingly, the reactions of
[Pt(η2-SCNMe2)(PPh3)2][PF6] with KS2COR (R = Me, Et) in
MeOH at room temperature for 2 h also gave dithiocarbonate
carbene-complexes[Pt(PPh3){η2(S,S)-S2COR]{C(SR)(NMe2)}]
(R = Me, 6; Et, 7).‡ It is clear that in the reactions of
thiocarbamoyl Pd and Pt complexes with KS2COR (R = Me,
Et) ligands, the intramolecular alkyl-thiocarbamoyl coupling
reaction occurs. Olefin metathesis reactions of 3 and 4 are
currently under investigation.
1 M. Schmittel, D. Rodriguez and J. P. Steffen, Angew. Chem. Int. Ed.,
2000, 39, 2152 and references therein. K. Aparna, R. McDonald and
R. G. Cavell, J. Am. Chem. Soc., 2000, 122, 9314 and references
therein. L. D. Field, W. J. Shaw and P. Turner, Organometallics, 2001,
20, 3491 and references therein.
2 T. R. Gaffney and J. A. Ibers, Inorg. Chem., 1982, 21, 2860;
H. Werner, W. Bertleff, B. Zimmer-Gasser and U. Schubert, Chem.
Ber., 1982, 115, 1004; T. R. Gaffney and J. A. Ibers, Inorg. Chem.,
1982, 21, 2851; C. Bianchini, A. Meli and A. Orlandini, Inorg.
Chem., 1982, 21, 4166.
3 F. Cecconi, C. A. Ghilardi, S. Midollini, S. Moneti, A. Orlandini and
G. Scapacci, J. Chem. Soc., Dalton Trans., 1989, 211; C. Bianchini,
C. A. Ghilardi, A. Meli and A. Orlandini, J. Organomet. Chem.,
1985, 286, 259; C. Bianchini and A. Meli, J. Chem. Soc., Dalton
Trans., 1983, 2419; C. Bianchini and A. Meli, Inorg. Chem., 1987, 26,
4268; C. Bianchini, C. Mealli, A. Meli and M. Sabat, J. Chem. Soc.,
Chem. Commun., 1985, 1024.
4 R. Colton, J. C. Traeger and V. Tedesco, Inorg. Chim. Acta, 1993,
210, 193; R. Colton and V. Tedesco, Inorg. Chim. Acta, 1992, 202,
95; R. Colton and V. Tedesco, Inorg. Chim. Acta, 1991, 183, 161.
5 J. Doherty, J. Fortune, A. R. Manning and F. S. Stephens, J. Chem.
Soc., Dalton Trans., 1984, 1111.
Acknowledgements
We thank the National Science Council of Taiwan, the
Republic of China (project: NSC92-2113-241-001) for financial
support and Mrs S.-L. Huang for carrying out NMR
experiments.
6 R. Rossi, A. Marchi, L. Margon, U. Casellato and R. Graziani,
J. Chem. Soc., Dalton Trans., 1990, 2923.
7 K. H. Yih, G. H. Lee and Y. Wang, Inorg. Chem. Commun., 2003, 6,
577; K. H. Yih, G. H. Lee and Y. Wang, Inorg. Chem. Commun.,
2003, 6, 213; K. H. Yih, G. H. Lee and Y. Wang, Inorg. Chem., 2003,
Notes and references
1
‡ Selected spectroscopic data: H (500 MHz) and 13C{1H} (125 MHz)
NMR (CDCl3, relative to SiMe4, multiplicity, assignment, J in Hz)
31P{1H} (202 MHz) NMR (H3PO4 external standard). 3: IR (KBr)
D a l t o n T r a n s . , 2 0 0 3 , 2 8 1 0 – 2 8 1 2
2811

View Article Online
42, 1092; K. H. Yih, G. H. Lee, S. L. Huang and Y. Wang, Organo-
metallics, 2002, 21, 5767.
8 K. H. Yih, Y. C. Lin, M. C. Cheng and Y. Wang, J. Chem. Soc.,
Chem. Commun., 1993, 1380; K. H. Yih, Y. C. Lin, M. C. Cheng and
Y. Wang, J. Chem. Soc., Dalton Trans., 1995, 1305.
545 and references cited therein. W. M. Butler and J. H. Enemark,
Inorg. Chem., 1973, 12, 451; O. P. Anderson and A. B. Packard,
Inorg. Chem., 1978, 17, 1333; R. D. Wilson, K. Kamitori, H. Ogoshi,
Z. Yoshida and J. A. Ibers, J. Organomet. Chem., 1979, 173, 199.
10 H. L. Bozec, P. H. Dixneuf, A. J. Carty and N. J. Taylor, Inorg.
Chem., 1978, 17, 2568.
9 D. J. Cardin, B. Cetinkaya and M. F. Lappert, Chem. Rev., 1972, 72,
D a l t o n T r a n s . , 2 0 0 3 , 2 8 1 0 – 2 8 1 2
2812