Sulfur-assisted chloride and triphenylphosphine dissociation of palladium(II) complex. See abstract

Article abstract of DOI:10.1016/S1387-7003(03)00043-1

Treatment of Pd(PPh₃)₄ with Me₂NC(=S)Cl in dichloromethane at -20 °C produces the complex [Pd(PPh₃)₂(η¹-SCNMe₂) (Cl)], 2. Variable temperature ¹H and ³¹P{H}

Full text of DOI:10.1016/S1387-7003(03)00043-1

Inorganic Chemistry Communications 6 (2003) 577–580
www.elsevier.com/locate/inoche
Sulfur-assisted chloride and triphenylphosphine dissociation
of palladium(II) complex [Pd(PPh3)2(g1-SCNMe2)(Cl)]. X-ray
structures of [Pd(PPh3)2(g1-SCNMe2)(Cl)], [Pd(PPh3)(Cl)]2
(l; g2-SCNMe2)2, and [Pd(PPh3)2(g2-SCNMe2)][PF6]
a,
b
c
Kuang-Hway Yih *, Gene-Hsiang Lee , Yu Wang
a
Department of Applied Cosmetology, Hung Kuang 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 22 November 2002; accepted 25 January 2003
Abstract
Treatment of PdðPPh3Þ4 with Me2NCð@SÞCl in dichloromethane at )20 °C produces the complex ½PdðPPh3Þ2ðg1-SCNMe2Þ
1
ðClފ, 2. Variable temperature H and 31P{H} NMR experiments of complex 2 shows the dissociation of either the chloride or the
triphenylphosphine ligand to form complex ½PdðPPh3Þ2ðg2-SCNMe2ފ½ClŠ, 3 or the dipalladium complex ½PdðPPh3ÞClŠ2ðl; g2-
SCNMe2Þ2, 4. The reaction of complex 2 with NaPF6 affords complex ½PdðPPh3Þ2ðg2-SCNMe2ފ½PF6Š, 5. Complexes 2, 4, and 5 are
characterized by X-ray diffraction analyses.
Ó 2003 Elsevier Science B.V. All rights reserved.
Keywords: Dissociation behaviour; N,N-dimethylthiocarbamoyl; Palladium; Sulfur-assisted; X-ray diffraction
The study of transition-metal compounds containing
the N,N-dialkylthiocarbamonyl ligand (ÀSCNR2) is of
interest in that this ligand may behave like a mono- or
bidentate in ether, resulting in novel structural and
chemical features [1]. We have recently been investigat-
ing the chemistry of sulfur-containing heteroallenes and
related molecules with mono- and binuclear systems in
order to obtain a better understanding of how these
molecules interact with the metal center [2]. In this pa-
per, we report the preparation and properties of palla-
dium complexes with the ÀSCNMe2 containing ligand.
Treatment of PdðPPh3Þ4, 1 with Me2NCð@SÞCl in
dichloromethane at )20 °C yields the yellow complex
[PdðPPh3Þ2ðg1-SCNMe2ÞðClÞ], 2 (Scheme 1). The vari-
three sets of triphenylphosphine resonances at 233 K in
CDCl3. As depicted in Fig. 1, the three sets of reso-
nances are assigned to the 2 and the dissociation of ei-
ther the chloride of 2 to form the mononuclear complex
½PdðPPh3Þ2ðg2-SCNMe2ފ½ClŠ, 3 or the triphenylphos-
phine ligand of 2 to form the dipalladium complex
½PdðPPh3ÞClŠ2ðl; g2-SCNMe2Þ2, 4. Continuous stirring
dichloromethane solution of complex 2 at room tem-
perature for 8 h produces complex 4 as the ultimate
product. The spectroscopic [3]and analytical data of 2–4
are obtained. Complex [PdðPPh3Þ2ðg1-CH2SCH3ÞCl]
[4a]is the one only reported example including the dis-
sociation observation to form monomer complexes
[PdðPPh3Þðg2-CH2SCH3ÞCl]and [Pd ðPPh3Þ2ðg2-CH2
SCH3ފ½Cl]. From the above description, one can con-
clude that the sulfur atom of SCNMe2 ligand assists
triphenylphosphine or chloride dissociation of 2 to form
4 or 3.
1
able temperature H and 31P{1H} NMR spectra of 2
show three sets of methyl resonances of SCNMe2 and
* Corresponding author. Fax: +886-4-26321046.
E-mail address: khyih@sunrise.hkc.edu.tw (K.-H. Yih).
The dissociation of the chloride ligand from 2 also
can be confirmed by the shorter reaction time of 2 with
1387-7003/03/$ - see front matter Ó 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S1387-7003(03)00043-1

578
K.-H. Yih et al. / Inorganic Chemistry Communications 6 (2003) 577–580
Scheme 1.
Fig. 1. Variable-temperature 1H (a) and 31P{1H} NMR (b) spectra of the mixtures 2, 3, and 4 in CDCl3 (x as the impurity).
NaPF6 in acetone at room temperature to form complex
½PdðPPh3Þ2ðg2-SCNMe2ފ½PF6Š, 5 (5 min) than those of
chloride abstraction reaction of complex [C6H4CH2
NMe2)Pd(Cl)(2,6-dimethoxyphenyl)diphenylphosphine]
[4b]with NaPF (3 h) and [PdðPPh3Þ ðCH2SCH3ÞCl]
shows two doublet resonances at d 23.1 and d 35.1 due
to the chemical inequivalence of the two PPh3 ligands
and the relative downfield resonance than that of 2 (d
16.6) which shows the cationic character of 5. From the
description, it is clear that the palladium of 5 is side-on
bound through the C–S moiety of the SCNMe2 ligand.
The compounds 2, 4, and 5 were recrystallized from
CH2Cl2/n-hexane (1:10) and were isolated in 98%, 93%
and 92% yield, respectively.
Single crystals of 2, 4, and 5 suitable from X-ray
diffraction studies [6]were grown by slow n-hexane
diffusion into a dichloromethane solution at 4 °C. OR-
TEP plots of 2, 4, and 5 are shown in Figs. 2–4. In
6
2
with NH4PF6 (15 min) in the same reactive conditions.
The spectroscopic [5]and analytical data of 5 are in
good agreement with the formulation. The 1H and
31P{1H} NMR spectra of 5 are similar to those of 3. In
1
the H NMR spectrum of 5, the two methyl protons of
the SCNMe2 ligand exhibit two resonances at d 2.54 and
d 3.61. The corresponding 13C{1H} NMR signals are at
d 45.9 and d 53.9. The 31P{1H} NMR spectrum of 5

K.-H. Yih et al. / Inorganic Chemistry Communications 6 (2003) 577–580
579
Fig. 2. An ORTEP drawing with 30% thermal ellipsoids and atom-
numbering scheme for the complex [PdðPPh3Þ2ðg1-SCNMe2ÞðClÞ], 2.
ꢀ
Selected bond distances (A) and angles (°) are as follows: Pd–P(1)
Fig. 4. An ORTEP drawing with 30% thermal ellipsoids and atom-
numbering scheme for the cationic complex ½PdðPPh3Þ2ðg2-SCNMe2ފ
2.3531(9), Pd–P(2) 2.3401(9), Pd–Cl(1) 2.4067(9), Pd–C(1) 1.982(3),
C(1)–S(1) 1.679(4), C(1)–N(1) 1.320(4), C(2)–N(1) 1.458(5), C(3)–N(1)
1.457(5); C(1)–Pd–Cl(1) 166.32(10), P(1)–Pd–P(2) 173.75(3), Cl(1)–Pd–
P(1) 93.50(3), Cl(1)–Pd–P(2) 91.13(3), C(1)–Pd–P(1) 87.50(10), C(1)–
Pd–P(2) 89.00(10), S(1)–C(1)–Pd 111.61(18), S(1)–C(1)–N(1) 124.7(3),
N(1)–C(1)–Pd 123.6(3).
ꢀ
½PF6Š, 5. Selected bond distances (A) and angles (°) are as follows: Pd–
P(1) 2.3125(15), Pd–P(2) 2.3660(16), Pd–S(1) 2.3243(15), Pd–C(1)
2.003(6), C(1)–S(1) 1.667(6), C(1)–N(1) 1.303(7), C(2)–N(1) 1.468(7),
C(3)–N(1) 1.466(7); C(1)–Pd–S(1) 44.54(16), P(1)–Pd–P(2) 103.66(5),
S(1)–Pd–P(1) 151.36(6), S(1)–Pd–P(2) 104.92(5), C(1)–Pd–P(1)
106.82(16), C(1)–Pd–P(2) 149.15(16), S(1)–C(1)–Pd 78.0(2), S(1)–C(1)–
N(1) 131.5(4), N(1)–C(1)–Pd 150.5(4), C(1)–S(1)–Pd 57.4(2).
the geometries are consistent with significant partial
double bond character in the C–S and SC–N bonds.
ꢀ
Thus, the C–S bond distances (1.679(4) A of 2, 1.731(4)
ꢀ
ꢀ
and 1.718(4) A of 4, and 1.667(6) A of 5) are comparable
to the C–S double bond in ethylenethiourea although
ꢀ
they are longer than those in free CS2 (1.554 A). The
ꢀ
SC–N bond distances (1.320(4) A of 2, 1.316(5) and
ꢀ
ꢀ
1.318(5) A of 4, and 1.303(7) A of 5) are typical for a
C–N bond having partial double bond character and are
ꢀ
certainly much shorter than the normal C–N (1.47 A)
single bond. The Me–N distances are normal for single
bonds and are significantly longer than those of SC–N
bonds, which, as noted, have multiple bond character.
In complex 5, the Pd atom and its neighboring atoms,
P(1), P(2), S(1), and C(1) lie in a distorted squared plane.
The distortion is mainly due to the short bite of the C@S
linkage [C–Pd–S, 44.54(16)°]. A least-squares plane cal
culation reveals that the planarity of the P(2)P(1)C(1)
Fig. 3. An ORTEP drawing with 50% thermal ellipsoids and
atom-numbering scheme for the complex ½PdðPPh3ÞClŠ ðl; g2-
2
ꢀ
SCNMe2Þ2, 4. Selected bond distances (A) and angles (°) are as
follows: Pd(1)Á Á ÁPd(2) 3.334(2), Pd(1)–P(1) 2.3046(10), Pd(2)–P(2)
2.3013(9), Pd(1)–Cl(1) 2.3721(10), Pd(2)–Cl(2) 2.3677(9), Pd(1)–C(1)
1.969(4), Pd(2)–C(4) 1.989(4), C(1)–S(1) 1.731(4), C(4)–S(2) 1.718(4);
C(1)–Pd(1)–Cl(1) 178.55(11), C(4)–Pd(2)–Cl(2) 178.05(10), Cl(1)–
Pd(1)–P(1) 87.26(3), Cl(2)–Pd(2)–P(2) 84.95(3), C(1)–Pd(1)–P(1)
93.41(11), C(4)–Pd(2)–P(2) 93.51(10), S(1)–C(1)–Pd(1) 116.93(19),
S(2)–C(4)–Pd(2) 117.7(2).
ꢀ
S(1) core (largest deviation 0.031(1) A). The C(1)–S(1)
ꢀ
bond distance of 1.667(6) A is similar to the corre-
sponding carbon–sulfur bond distance observed in
g2-CS2 (sp ) transition-metal complexes [1.65(3) A in
2
ꢀ
[ðPPh3Þ2Pdðg2-CS2Þ][.7] The Pd–S(1) distance of
complex 2, the SCNMe2 ligand is r-bounding to Pd
atom through the carbon atom of the thiocarbonyl
ꢀ
group. The S–Pd bond distance of 3.033 A in 2 indicates
no bonding interaction between the sulfur atom and
palladium metal atom. Complex 4 is a dimer with each
SCNMe2 unit bridging through carbon atom of thio-
carbonyl group to one metal center and sulfur atom to
the other metal. Within the SCNMe2 ligands themselves,
ꢀ
ꢀ
2.3243(5) A is within the normal Pd–S length range
(2.23–2.32 A) [8]. Our interest in the M–CðSÞNMe2 and
M–C(S)OPh moieties are due to their analogies with
metallocarboxylic acid esters (M–C(O)OR) and metal-
locarboxylic acids themselves. Metallocarboxylic acids
have been proposed to be the key intermediates in the
homogeneous catalysis of the water gas shift reaction

580
K.-H. Yih et al. / Inorganic Chemistry Communications 6 (2003) 577–580
[9]. Reactions and different bonding modes of 2 and
nucleophiles are currently under investigation.
[3]Spectroscopy for 2: 31P {1H} NMR: d 16.6 (br, PPh3). 1H NMR: d
2.34, 2.64 (s, 6H, NCH3), 7.31–8.05 (m, 30H, Ph). 13C{1H} NMR: d
41.5 (s, NCH3), 128.4–135.8 (m, C of Ph), 223.5 (s, CS). Anal.
Calcd. for C39H36ClNP2SPd: C, 62.08; H, 4.81; N, 1.86%. Found:
C, 62.10; H, 4.81; N, 1.84. Spectroscopy for 3: 31P{1H} NMR: d
2
23.1, 35.1 (d, JP–P ¼ 40:7). 1H NMR: d 2.39, 3.58 (s, 6H, NCH3),
Acknowledgements
7.31–8.05 (m, 30H, Ph). 13C{1H} NMR: d 46.1, 53.4 (s, NCH3),
128.4–135.8 (m, C of Ph). Spectroscopy for 4: 31P{1H} NMR: d
19.8 (s, PPh3). 1H NMR: d 2.51, 3.44 (s, 6H, NCH3), 7.28–8.05 (m,
15H, Ph). 13C{1H} NMR: d 39.9, 49.1 (s, NCH3), 128.4–135.8 (m,
C of Ph), 234.4 (s, CS). Anal. Calcd. for C42H42Cl2N2P2S2Pd2: C,
51.23; H, 4.30; N, 2.85%. Found: C, 51.28; H, 4.21; N, 2.80.
[4](a) G. Yoshida, H. Kurosawa, R. Okawara, J. Organomet. Chem.
113 (1976) 85;
We thank the National Science Council of Taiwan,
the Republic of China (NSC91-2113-214-002) for sup-
port.
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d 23.2, 34.8 (d, 2JP–P ¼ 40:7, PPh3), )144.0 (sep, JP–F ¼ 708:6, PF6).
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2
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ꢀ
ꢀ
ꢀ
a ¼ 12:8248ð1Þ A, b ¼ 18:6358ð1Þ A, c ¼ 14:9692ð1Þ A, b ¼
ꢀ3
105:1513ð4Þ°, V ¼ 3453:28ð5Þ A , Z ¼ 4, Dcalcd ¼ 1:451 gcmÀ3
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,
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ꢀ
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ꢀ3
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ꢀ
ꢀ
Cl4N2P2Pd2S2, space group P1, a ¼ 9:8782ð1Þ A, b ¼ 11:4238ð1Þ A,
ꢀ
c ¼ 20:7353ð2Þ A, a ¼ 103:9126ð5Þ°, b ¼ 97:8453ð3Þ° c ¼
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ꢀ3
104:9669ð5Þ°, V ¼ 2166:76ð4Þ A , Z ¼ 2, Dcalcd ¼ 1:639 gcmÀ3
,
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,
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3939;
27:50°. Total number of parameters: 497. R ¼ 0:0409, Rw
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ꢀ
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ꢀ3
150ð1Þ K; DF ¼ 1:730, )1.261e A . Crystal data for 5:
ꢀ
C39H36F6NP3PdS Á CH2Cl2, space group P21=c, a ¼ 9:8101ð1Þ A,
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ꢀ
ꢀ
b ¼ 23:5315ð3Þ A, c ¼ 18:2112ð2Þ A, b ¼ 103:2337ð5Þ°, V ¼
ꢀ3
4092:35ð4Þ A , Z ¼ 4, Dcalcd ¼ 1:540 gcmÀ3; l ¼ 0:810 mmÀ1, inde-
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ꢀ
ꢀ3
radiation; k ¼ 0:71073 A ; T ¼ 150ð1Þ K; DF ¼ 1:543, )1.136e A .
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