Synthesis, structures and spectroscopic properties of cyclometalated tri-tert-butylphosphine complexes of platinum(II)

Article abstract of DOI:10.1016/j.jorganchem.2010.07.005

Reactions of [Pt₂(μ-Cl)₂(C^∩P) ₂] (C^∩P = CH₂C(Me₂)PBu ^t₂-C,P) with various anionic ligands differing in ligand bite and denticity have been investigated and the resulting products have been characterized by elemental analyses and NMR (¹H, ¹³C, ³¹P, ¹⁹⁵Pt) spectroscopy. Stereochemistry of the complexes has been deduced by NMR spectroscopy. Structures of [Pt₂(μ-SPh) ₂(C^∩P)₂], [Pt₂(μ-pz) ₂(C^∩P)₂], [PtCl(Spy)(PBu^t ₃)], [Pt₂(μ-SCOPh)₂(C^∩P) ₂] and [Pt{S₂P(OPrⁱ)₂}(C ^∩P)] have been established by single crystal X-ray diffraction analyses. The complex [Pt₂(μ-SPh)₂(C ^∩P)₂] adopts a sym cis configuration while other binuclear complexes exist in a sym trans configuration. The molecular structure of [Pt{S₂P(OPrⁱ)₂}(C^∩P)] revealed that complex comprises of two four-membered chelate rings but in solution a dimeric structure based on ¹⁹⁵Pt NMR data has been suggested.

Full text of DOI:10.1016/j.jorganchem.2010.07.005

Journal of Organometallic Chemistry 695 (2010) 2296e2304
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, structures and spectroscopic properties of cyclometalated tri-tert-
butylphosphine complexes of platinum(II)
*
*
Ninad Ghavale, Amey Wadawale, Sandip Dey , Vimal K. Jain
Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Reactions of [Pt2(
m
-Cl)2(CXP)2] (CXP ¼ CH2C(Me2)PBut2-C,P) with various anionic ligands differing in
Received 17 May 2010
Received in revised form
28 June 2010
Accepted 6 July 2010
Available online 14 July 2010
ligand bite and denticity have been investigated and the resulting products have been characterized by
elemental analyses and NMR (1H, 13C, 31P, 195Pt) spectroscopy. Stereochemistry of the complexes has been
deduced by NMR spectroscopy. Structures of [Pt2(
[Pt2(
-SCOPh)2(CXP)2] and [Pt{S2P(OPri)2}(CXP)] have been established by single crystal X-ray diffraction
analyses. The complex [Pt2(
m m
-SPh)2(CXP)2], [Pt2( -pz)2(CXP)2], [PtCl(Spy)(PBut3)],
m
m
-SPh)2(CXP)2] adopts a sym cis configuration while other binuclear
complexes exist in a sym trans configuration. The molecular structure of [Pt{S2P(OPri)2}(CXP)] revealed
that complex comprises of two four-membered chelate rings but in solution a dimeric structure based on
195Pt NMR data has been suggested.
Keywords:
Platinum
Anionic ligand
Cyclometalation
NMR
Ó 2010 Elsevier B.V. All rights reserved.
X-ray diffraction
1. Introduction
complexes containing five-membered metalated ligands and quite
often with E ¼ nitrogen donor atom. To access the reactivity of
Ever since the first report of cyclopalladation reaction by Cope
and Siekman [1], there has been sustained interest in the chemistry
of cyclometalated compounds of palladium(II) and platinum(II) [2].
These complexes find numerous applications such as catalysts in
organic synthesis [3,4], metallomesogens [5,6] and exhibit
remarkable photo physical properties [7e9]. A myriad of organic
ligands containing N, P, S, etc. donor atoms undergo cyclo-
metalation reaction leading to the formation of, in most of the
cases, five-membered “EXCM” (M ¼ Pd, Pt) ring. Cyclometalated
binuclear palladium and platinum complexes undergo a wide
variety of reactions viz., bridge cleavage by neutral donor ligands,
reaction at the metal carbon bond and substitution of the bridging
ligand (e.g. Cl or OAc) with another anionic ligand. The latter
reaction has been employed to prepare numerous complexes.
Depending on the nature of E, incoming ligand and the metal atom,
structural diversity in the resulting complexes is not uncommon
binuclear complexes derived from a strained four-membered
metalated ligand, we have chosen binuclear chloro-bridged plat-
inum complex containing metalated tri-tert-butylphosphine,
[Pt2(
m
-Cl)2(CXP)2] (CXP ¼ CH2C(Me2)PBut2-C,P) and carried out
reactions with one-, two- and three-atom anionic ligands. The
results of this work are reported herein.
2. Experimental
2.1. General procedures and instrumentation
Tri-tert-butylphosphine, HSpy, PhCOSH and other reagents were
procured from commercial sources. The complexes [PtCl2(PhCN)2]
[12] and [Pt2(m
-Cl)2{CH2C(Me2)PBut2-C,P}2] [m.p. 207 ꢀC (dec.);
UVevis (CH2Cl2) lmax: 262, 310 nm. 31P{1H} NMR (CDCl3)
d
: ꢁ16.3
(1J(PteP) ¼ 3755 Hz); ꢁ16.6 (1J(PteP) ¼ 3788 Hz); 195Pt{1H}NMR
(CDCl3)
d
: ꢁ3622 (1J(PteP) ¼ 3784 Hz, 3J(PteP) ¼ 245 Hz), ꢁ3660
[2]. For instance, the reaction of [Pt2(
C6H4eC5H4N) with pyEH (E ¼ O or S) yields readily platinum(III)
complexes, [Pt2Cl2( -Epy)2(ppy)2] [10], but a similar reaction of
[Pd2( -Cl)2(Me2NCH2C6H4-o)2] with pySH affords binuclear
complex, [Pd2( -Spy)2(Me2NCH2C6H4-o)2] [11]. Most of the
m
-Cl)2(ppy)2] (ppy ¼ 2-
(1J(PteP) ¼ 3752 Hz, 3J(PteP) ¼ 206 Hz)] [13] and the ligands tol-
m
NNNHtol [14], PhNCMeNHPh [15] and their silver salts [16], NaS2
-
COEt [17], NH4[S2P(OPri)2] [18] and Pb(SPh)2 [19] were prepared
according to literature methods.
m
a
m
substitution reactions have been investigated on binuclear
Solvents were dried by standard methods with subsequent
distillation under nitrogen. All the reactions were carried out in
Schlenk flask under a nitrogen atmosphere. Melting points were
determined in capillary tubes and are uncorrected. Absorption
* Corresponding authors. Tel.: þ91 22 2559 5095; fax: þ91 22 2550 5151.
E-mail addresses: dsandip@barc.gov.in (S. Dey), jainvk@barc.gov.in (V.K. Jain).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.07.005

N. Ghavale et al. / Journal of Organometallic Chemistry 695 (2010) 2296e2304
2297
spectra were recorded on a Chemito Spectrascan UV 2600 spec-
trophotometer. Elemental analyses were carried out on a Carlo-
Erba EA-1110 CHN-O instrument. IR spectra were recorded as Nujol
mulls between CsI plates on a Bomem MB-102 FT-IR spectrometer.
1H, 13C{1H}, 31P{1H} and 195Pt{1H} NMR spectra were recorded on
a Bruker Avance II-300 NMR spectrometers operating at 300, 75.47,
121.5 and 64.29 MHz, respectively. Chemical shifts are relative to
reaction mixture was further stirred for 2 h. The solvent was evap-
orated and the solid residue was extracted with dichloromethane
(3 ꢂ 10 mL). The extract was passed through a celite column and
concentrated to 5 mL and 2 mL of hexane was added for crystalli-
zation. The solution on cooling at ꢁ5 ꢀC gave colorless crystals of 4
(85 mg, 70%). m.p.: 147 ꢀC. Anal. Calcd for C34H66N4P2Pt2: C, 41.5; H,
6.8; N, 5.6. Found: C, 41.2; H, 6.5; N, 5.0%. UVevis (CH2Cl2) lmax in nm
internal chloroform peak (
d
7.26 1H and 77.0 for 13C), external 85%
(3 d: 1.47
in Mꢁ1 cmꢁ1): 234 (17000); 249 (21000). 1H NMR (CDCl3)
H3PO4 for 31P{1H} and Na2PtCl6 for 195Pt{1H}.
(d, 3J(PeH) ¼ 13.8 Hz; CMe2); 1.57 (d, 3J(PeH) ¼ 13.5 Hz, CMe3); 2.13,
2.21 (each s, 3,5-Me2 of dmpz, major product); 2.26, 2.31 (each s, 3,5-
Me2, dmpz, minor product); 2.37 (d, 3J(PeH) ¼ 6 Hz, CH2); 5.77 (s,
minor); 5.83 (s, major) (CH-4; dmpz). 13C{1H} NMR: ꢁ0.7 (d, J
(PeC) ¼ 27 Hz, 1J(PteC) ¼ 642 Hz, CH2 major); ꢁ2.4 (d, J
(PeC) ¼ 27 Hz, CH2 minor); 10.8, 13.6 (Me2, pz); 14.7 (Me, dmpz,
minor); 31.4 (CMe3); 32.0 (s, CMe3, minor); 32.8 (CMe2); 32.6 (d, J
(PeC) ¼ 19 Hz); 37.2 (d, J(PeC) ¼ 18 Hz); 54.0 (d, J(PeC) ¼ 28 Hz,
2.2. Synthesis of complexes
2.2.1. Synthesis of [Pt2(
m
-SPh)2{CH2C(Me2)PBut2-C,P}2] (1)
-Cl)2{CH2C(Me2)
To a dichloromethane (15 mL) solution of [Pt2(
m
PBut2-C,P}2] (82 mg, 0.095 mmol) was added solid [Pb(SPh)2]
(41 mg, 0.096 mmol) and the mixture was further stirred for 2 h.
The reaction mixture was allowed to stand for 0.5 h. The super-
natant solution was decanted and filtered through a celite column.
The filtrate was concentrated and kept at 0e5 ꢀC for crystallization
to yield pale yellow crystals of 1 (50 mg, 52%). m.p.: 199 ꢀC. Anal.
Calcd for C36H62P2Pt2S2: C, 42.7; H, 6.2; S, 6.3. Found: C, 42.7; H, 6.1;
CMe2); 104.4; 104.8; 106.5 (pz). 31P{1H} NMR (CDCl3)
d
: ꢁ17.3 (1J
(PteP) ¼ 3255 Hz) (major); ꢁ15.1 (1J(PteP) ¼ 3270 Hz) (minor).195Pt
{1H} NMR (CDCl3)
d
: ꢁ3809 (1J(PteP) ¼ 3278 Hz, J(PteP0) ¼ 218 Hz,
major isomer), ꢁ3836 (1J(PteP) ¼ 3286 Hz, minor) ppm.
S, 6.0%. UVevis (CH2Cl2) lmax in nm (
3
in Mꢁ1 cmꢁ1): 260 (34400).
2.2.5. Synthesis of [Pt2(
m
-OAc)2{CH2C(Me2)PBut2-C,P}2] (5)
-Cl)2{CH2C(Me2)
1H NMR (CDCl3):
d
0.93 (d, 3J(PeH) ¼ 9.6 Hz, 2J(PteH) ¼ 97 Hz, CH2-
To a dichloromethane (20 mL) solution of [Pt2(m
); 1.36 (d, 3J(PeH) ¼ 13.8 Hz, CMe2); 1.49 (d, 3J(PeH) ¼ 13 Hz, PBut2);
PBut2-C,P}2] (119 mg, 0.14 mmol), solid AgOAc (47 mg, 0.28 mmol)
was added with stirring. After 3 h, the pinkish white precipitate
formed was separated by centrifugation and the supernatant was
treated with animal charcoal and filtered through a celite column.
The filtrate was dried and the white residue was recrystallized from
benzeneehexane mixture to yield white crystals of 5 (40 mg, 32%).
m.p.: 179 ꢀC (darkens at 172 ꢀC). Anal. Calcd for C28H58O4P2Pt2: C,
6.99e7.19 (m, H-3-5, Ph); 7.61, 7.90 (each d, 7.2 Hz, H-2,6, Ph). 13C
{1H} NMR (CDCl3)
d
: 8.4 (d, 2J(PeC) ¼ 26 Hz, CH2); 31.6 (s, CMe3);
32.7 (s, CMe2); 37.5 (d, J(PeC) ¼ 11 Hz, CMe3); 54.3 (d, 1J
(PeC) ¼ 28 Hz); 124.0, 124.9, 125.3, 126.8, 127.2, 134.3, 134.4, 138.0
(SPh). 31P{1H} NMR (CDCl3):
d
ꢁ9.6 (1J(PteP) ¼ 3049 Hz). 195Pt{1H}
NMR (CDCl3)
ppm.
d
: ꢁ3836 (1J(PteP) ¼ 3020 Hz; 3J(PteP) ¼ 195 Hz)
36.9; H, 6.4. Found: C, 36.8; H, 6.1%. UVevis (CH2Cl2) lmax in nm (
3
:
in Mꢁ1 cmꢁ1): 243 (14000); 269 (sh); 302 (1800). IR yC¼O
2.2.2. Synthesis of [Pt2(
m
-SePh)2{CH2C(Me2)PBut2-C,P}2] (2)
1561 cmꢁ1. 1H NMR (CDCl3)
(s, OAc). 13C{1H} (CDCl3)
d
: 1.43e1.57 (m, metalated PBut3); 1.97
The complex was prepared according to literature method [20].
d
:
ꢁ8.8 (d, 3J(PeC)
¼
25 Hz, 1J
1H NMR (CDCl3)
(d, 12 Hz, CMe3); 7.10e8.00 (m, Ph). 31P{1H} NMR (CDCl3)
d
: 1.05 (d, 9.7 Hz, CH2); 1.39 (d, 13.6 Hz, CMe2); 1.53
(PteC) ¼ 632 Hz, CH2e); 25.2 (s, OAc); 31.4 (CMe3); 31.5 (CMe2);
d
: ꢁ8.8 (1J
36.8 (s, CMe3); 55.0 (s, CMe2); 180.6 (CO). 31P{1H} NMR (CDCl3)
d:
(PteP)
¼
3049 Hz). 195Pt{1H} NMR (CDCl3)
d:
ꢁ4035 (1J
ꢁ22.3 (1J(PteP) ¼ 3866 Hz). 195Pt{1H} NMR (CDCl3)
(PteP) ¼ 3962 Hz) ppm.
d
: ꢁ3507 (d, 1J
(PteP) ¼ 3043 Hz, 3J(PteP) ¼ 186 Hz) ppm.
2.2.3. Synthesis of [Pt2(
m
-pz)2{CH2C(Me2)PBut2-C,P}2] (3)
-Cl)2{CH2C(Me2)PBut2-C,P}2] (113 mg,
2.2.6. Synthesis of [Pt2(tolNNNtol)2{CH2C(Me2)PBut2-C,P}2] (6)
To a dichloromethane (15 mL) solution of [Pt2( -Cl)2{CH2C(Me2)
To a suspension of [Pt2(
m
m
0.13 mmol) in methanol (10 mL), methanolic NaOH (6 mL, 0.11 M)
was added drop wise till a clear solution was obtained. After stirring
for 10 min, a methanolic solution (5 mL) of pzH (19 mg, 0.28 mmol)
was added and the reaction mixture was further stirred for 2 h.
A white precipitate was formed which was separated by decanta-
tion of supernatant solution and washed with methanol, dried and
recrystallized from benzene to yield colorless crystals of 3 (54 mg,
44%). m.p.: 213 ꢀC. Anal. Calcd for C30H58N4P2Pt2: C, 38.8; H, 6.3; N,
PBut2-C,P}2] (104 mg, 0.12 mmol), solid Ag(ditolyltriazine) (79 mg,
0.24 mmol) was added and the mixture was stirred for 2 h. The
color of the solution turned orange. The solution was decanted and
filtered through celite. The filtrate was concentrated to 4 mL and
1 mL of hexane was added and cooled at ꢁ5 ꢀC to yield orange
crystals of
6
(113 mg, 75%). m.p.: 209 ꢀC. Anal. Calcd for
C52H80N6P2Pt2: C, 50.3; H, 6.5; N, 6.8. Found: C, 50.2; H, 6.4; N, 6.9%.
UVevis (CH2Cl2) lmax in nm (
3
in Mꢁ1 cmꢁ1): 243 (37100); 282
6.0. Found: C, 38.7; H, 6.3; N, 5.9%. UVevis (CH2Cl2) lmax in nm (
ꢁ1 cmꢁ1): 236 (19700); 247 (21200); 272 (5800). 1H NMR (CDCl3)
: 1.34 (d, 12.9 Hz); 1.41e1.67 (m, Me2 þ CH2); 1.63 (d, 12.9 Hz); 6.11
3
in
(34900); 312 (sh); 452 (28600). 1H NMR (CDCl3) : 1.52 (d, 3J
d
M
(PeH) ¼ 15.3 Hz, CMe2); 1.57 (d, 3J(PeH) ¼ 13.2 Hz, CMe3); 1.99 (d, 3J
(PeH) ¼ 9.3 Hz, CH2); 2.30, 2.31 (each s, tol-Me); 7.06 (m, C6H4);
d
(t, 1.8 Hz, CH-4); 7.41, 7.59 (s, CH-3,5). 13C{1H} NMR (CDCl3)
d: 0.11
7.20 (d, 8.4 Hz, C6H4). 13C{1H} NMR (CDCl3)
d
: ꢁ4.5 (d, 2J
(d, 2J(PeC) ¼ 25 Hz, 1J(195Pte13C) ¼ 548 Hz, CH2); 31.4 (d, J
(PeC) ¼ 22 Hz, CMe3); 32.8, 33.7 (CMe2); 35.3, 36.8 (d,15 Hz, CMe3);
53.8 (d, 29 Hz, CMe2); 103.7 (s, C-4 pz); 136.8 (s); 140.0 (s, C-3,5 pz).
(PeC) ¼ 29 Hz, 1J(PteC) ¼ 502 Hz, CH2); 20.9 (s, tol-Me); 31.5
(CMe3), 32.3 (CMe2); 36.7 (d, 1J(PeC) ¼ 12 Hz, CMe3); 54.8 (d, 1J
(PeC) ¼ 28 Hz, CMe2); 116.3; 117.4; 129.0 (each s, C6H4); 132.0;
31P{1H} NMR (CDCl3)
d
: ꢁ12.7 (1J(PteP) ¼ 3074 Hz); ꢁ16.0 (s, w5%).
132.6 (each s, C-1, C6H4); 146.4 (C-4, C6H4). 31P{1H} NMR (CDCl3)
d:
195Pt{1H} NMR (CDCl3)
d
: ꢁ3731 (d, 1J(PteP) ¼ 3065 Hz); ꢁ3863 (d,
ꢁ16.9 (1J(PteP) ¼ 2966 Hz). 195Pt{1H} NMR (CDCl3)
(PteP) ¼ 2969 Hz, J(Pt0-P) ¼ 195 Hz) ppm.
d
: ꢁ3555 (d, 1J
1J(PteP) ¼ 2957 Hz, w5%) ppm.
2.2.4. Synthesis of [Pt2(
m
-dmpz)2{CH2C(Me2)PBut2-C,P}2] (4)
-Cl)2{CH2C(Me2)PBut2-C,P}2] (106 mg,
2.2.7. Synthesis of [Pt2(PhNCMeNPh)2{CH2C(Me2)PBut2-C,P}2] (7)
To a benzene solution (20 mL) of [Pt2(
-Cl)2{CH2C(Me2)PBut2-
To a suspension of [Pt2(
m
m
0.12 mmol) in methanol, methanolic NaOH (6 mL, 0.11 M) was added
till a clear solution was obtained. After stirring for 10 min a meth-
anolic solution of dmpzH (23 mg, 0.24 mmol) was added and the
C,P}2] (118 mg, 0.13 mmol), solid Ag(PhNCMeNPh) (86 mg,
0.27 mmol) was added with stirring. After 3 h, the supernatant was
decanted and filtered through celite. The filtrate was dried and

2298
N. Ghavale et al. / Journal of Organometallic Chemistry 695 (2010) 2296e2304
extracted with methanol (2 ꢂ 10 mL) to yield a greenish-yellow
solid of 7 (80 mg, 48%). m.p.: 104 ꢀC. Anal. Calcd for C52H78N4P2Pt2:
C, 51.5; H, 6.5; N, 4.6. Found: C, 51.4; H, 6.6; N, 4.8%. UVevis (CH2Cl2)
(CDCl3)
d
: ꢁ5.2 (1J(PteP) ¼ 3066 Hz). 195Pt{1H} NMR (CDCl3)
d:
ꢁ4365 (d, 1J(PteP) ¼ 3066 Hz, 2J(PteP) ¼ 209 Hz) ppm.
lmax in nm (
3
in Mꢁ1 cmꢁ1): 236 (34100); 281 (32600); 351 (22400).
2.2.11. Synthesis of [Pt{S2P(OPri)2}{CH2C(Me2)PBut2-C,P}] (11)
1H NMR (CDCl3)
d
: 1.42 (d, J(PeH) ¼ 12 Hz, CMe3); 1.45 (d, J
To a dichloromethane (15 mL) solution of [Pt2(m-Cl)2{CH2C(Me2)
(PeH) ¼ 15.6 Hz, CMe2); 1.57 (d, J(PeH) ¼ 7.5 Hz, CH2); 1.91 (minor),
PBut2-C,P}2] (120 mg, 0.14 mmol) was added a methanolic solution
(10 mL) of NH4S2P(OPri)2 (64 mg, 0.28 mmol) and the whole was
further stirred for 2 h. The solvents were dried under reduced
pressure and the residue was extracted with benzene (3 ꢂ 10 mL)
and passed through celite. The filtrate was allowed to stand in air to
give white crystals which were washed with methanol and dried in
vacuum to yield 11 (59 mg, 35%). m.p.: 86 ꢀC. Anal. Calcd for
C18H40O2P2PtS2: C, 35.4; H, 6.6; S,10.5. Found: C, 35.5;H, 6.6; S,10.3%.
1.98 (major) (each s, CMe); 6.89e7.41 (m, Ph). 13C{1H} NMR (CDCl3)
d
: ꢁ4.5 (d, J(PeH) ¼ 29 Hz; 1J(PteH) ¼ 566 Hz, CH2); 19.1 (s, CMe);
31.1 (CMe3); 32.4 (CMe2); 36.3 (d, J(PeH) ¼ 14 Hz, CMe3); 54.9 (d, J
(PeH) ¼ 27 Hz, CMe2); 120.9, 122.3, 122.9, 124.6, 128.2, 146.3, 148.3
(Ph); 173.7 (CMe). 31P{1H} NMR (CDCl3)
d:
ꢁ13.9 (1J
(PteP) ¼ 3016 Hz, major); ꢁ17.2 (1J(PteP) ¼ 3193 Hz, minor). 195Pt
{1H} NMR (CDCl3)
d
: ꢁ3652 (d, J(PteP) ¼ 3031 Hz; J(Pt0-
1
P) ¼ 192 Hz) ppm.
UVevis (CH2Cl2) lmax in nm (
3
in Mꢁ1 cmꢁ1): 242 (10400); 297 (536).
1H NMR (CDCl3)
d: 1.39, 1.40 (each d, 6.3 Hz, OCHMe2); 1.48 (d, J
2.2.8. Synthesis of [PtCl(Spy)(PBut3)] (8)
(PeH) ¼ 13 Hz, CMe3); 1.50 (d, J(PeH) ¼ 14 Hz, CMe2); 1.62 (d, CH2);
To a methanolic suspension (20 mL) of [Pt2(m-Cl)2{CH2C(Me2)
5.00 (m, OCH). 13C{1H} NMR (CDCl3)
d
: 2.0 (d, J(PeC) ¼ 28 Hz, 1J
PBut2-C,P}2] (101 mg, 0.11 mmol), pyridine (5 mL) was added till
a clear solution was formed. HSpy (25 mg, 0.22 mmol) was added to
this reaction mixture, resulting a clear orange solution and the
whole was stirred for 3 h. The solvents were evaporated in vacuum,
the solid was extracted with dichloromethane (3 ꢂ 10 mL). The
extract was concentrated to 5 mL and 1 mL of hexane was added to
yield orange crystals of 8 (52 mg, 41%). m.p.: 87 ꢀC. Anal. Calcd for
C17H31ClNPPtS: C, 37.6; H, 5.7; N, 2.6; S, 5.9. Found: C, 38.0; H, 5.7;
(PteC) ¼ 568 Hz, CH2); 23.8 (OCHMe2); 31.2 (s, J(PteC) ¼ 17 Hz,
CMe3); 32.7 (s, J(PteC) ¼ 73 Hz, CMe2); 37.2 (d, J(PeC) ¼ 13 Hz,
CMe3); 56.2 (d, J(PeC) ¼ 27 Hz, CMe2); 72.0 (d, J(PeC) ¼ 4 Hz, OCH).
31P{1H} NMR (CDCl3)
d
: ꢁ6.8 (m,1J(PteP) ¼ 3250 Hz, PXC); 97.4 (d, 2J
(PteP) ¼ 122 Hz, PS-2). 195Pt{1H} NMR (CDCl3)
d
: ꢁ4297 (1J
(PteP) ¼ 3251 Hz, 2J(PtePthio) ¼ 118 Hz, J (PteP0phosphine) ¼ 110 Hz).
2.3. Crystallography
N, 2.7; S, 6.1%. UVevis (CH2Cl2) lmax in nm (3
in Mꢁ1 cmꢁ1): 285
(16900); 375 (3300). 1H NMR (CDCl3)
d
: 1.62 (d, 3J(PeH) ¼ 13 Hz,
Single crystal X-ray diffraction measurements were made on
PBut3); 6.60 (d, 8.4 Hz, H-3 py); 6.90 (t, H-4, py), 7.53 (t, 8 Hz, H-5
Rigaku AFC7S diffractometer at room temperature (298 ꢃ 2 K)
py), 8.51 (br, 3J(PteH) ¼ 43 Hz, H-6, py). 13C{1H} NMR (CDCl3)
d:
using graphite monochromated Mo-K
a
(l
¼ 0.71069 A) radiation.
ꢀ
32.9 (CMe3); 41.2 (CMe3); 116.7, 125.3, 138.6, 140.6 (each s, py) (C-2
Crystallographic data, together with data collection and refinement
details are given in Table 1. The structures were solved by direct
methods [21] and refinement was on F2 [22] using data corrected
for Lorentz and polarization effects with an empirical procedure
[23,24]. The non-hydrogen atoms were refined with anisotropic
displacement parameters and hydrogen atoms were fitted in their
calculated positions and refined in isotropic approximation using
riding model. Neutral atom scattering factors were taken from
Cromer and Waber [25]. All calculations were performed using
crystal structure crystallographic software package [26,27].
Molecular structures were drawn using ORTEP [28].
not detected from noise). 31P{1H} NMR (CDCl3)
d
: 54.9 (s, 1J
(PteP) ¼ 3732 Hz). 195Pt{1H} NMR (CDCl3)
(PteP) ¼ 3765 Hz) ppm.
d
: ꢁ3338.3 (d, 1J
2.2.9. Synthesis of [Pt2(
m
-SCOPh)2{CH2C(Me2)PBut2-C,P}2] (9)
-Cl)2{CH2C(Me2)
To a dichloromethane (15 mL) solution of [Pt2(
m
PBut2-C,P}2] (104 mg, 0.12 mmol), solid Ag(SCOPh) (60 mg,
0.26 mmol) was added and the mixture was stirred for 2 h. The
yellow solution was decanted and filtered through celite. The
filtrate was concentrated to 5 mL and 1 mL of hexane was added
and cooled at ꢁ5 ꢀC to yield orange crystals of the title complex
(106 mg, 82%). m.p.: 167 ꢀC (darkens above 140 ꢀC). Anal. Calcd for
C38H62O2P2Pt2S2: C, 42.7; H, 5.8; S, 6.0. Found: C, 42.4; H, 5.5; S,
3. Results and discussion
5.9%. UVevis (CH2Cl2) lmax in nm (
3
in Mꢁ1 cmꢁ1): 242 (45400). 1H
3.1. Synthesis and spectroscopy
NMR (CDCl3)
d
: 1.33e1.65 (m, metalated phosphine); 7.31e7.47 (m),
8.15 (d, 7.2 Hz), 8.34 (t, 7.2 Hz) (Ph). 31P{1H} NMR (CDCl3)
d
: ꢁ6.8 (1J
The starting complex [Pt2(m
-Cl)2{CH2C(Me2)PBut2-C,P}2] exists
(PteP) ¼ 3216 Hz) (minor); ꢁ8.9 (1J(PteP) ¼ 3210 Hz (major). 195Pt
as cis and trans isomers nearly in 1:1 ratio in solution as evidenced
from 31P{1H} and 195Pt{1H} NMR spectra. The 31P{1H} [13] and 195Pt
{1H} NMR spectra exhibits two sets of resonances attributable for
cis and trans isomers. A doublet of triplet appearing at lower field in
the 195Pt{1H}NMR spectrum has been assigned for the trans isomer.
Syntheses of various complexes have been carried out by the
{1H} NMR (CDCl3)
d
: ꢁ3884 (d, 1J(PteP) ¼ 3194 Hz, major); ꢁ3851
(d, 1J(PteP) ¼ 3188 Hz, minor) ppm.
2.2.10. Synthesis of [Pt(S2COEt){CH2C(Me2)PBut2-C,P}] (10)
To a dichloromethane solution (15 mL) of [Pt2(m-Cl)2{CH2C(Me2)
PBut2-C,P}2] (81 mg, 0.09 mmol), methanolic (10 mL) NaS2COEt
(28 mg, 0.19 mmol) was added with stirring. After 2 h, the reaction
mixture was filtered through celite and the filtrate was concen-
trated to 5 mL and 1 mL of hexane was added and cooled at ꢁ5 ꢀC to
yield yellow crystals (34 mg, 35%). m.p.: 111 ꢀC. Anal. Calcd for
C15H31OPPtS2: C, 34.8; H, 6.0; S, 12.4%. Found: C, 34.8; H, 5.9; S,
reactions of [Pt2(
m
-Cl)2(CXP)2] (CXP ¼ eCH2C(Me2)PBut2-C,P) with
anionic ligands (Scheme 1). The treatment of [Pt2(m
-Cl)2(CXP)2]
with Pb(EPh)2 (E ¼ S or Se) gave binuclear complexes, [Pt2(
m-
EPh)2(CXP)2] (E ¼ S (1) and Se (2)). These complexes have been
isolated exclusively as a sym cis isomer, although the corresponding
SR (R ¼ alkyl) bridged complexes exist as a mixture of cis and trans
isomers with the former predominating in solution [29]. The 31P
{1H} NMR spectra showed a single resonance with platinum
satellites. The 195Pt{1H} NMR spectra displayed a doublet of doublet
due to 1J(PteP) and 3J(PteP) (w190 Hz) couplings. The magnitude
of 1J(PteP) (w3050 Hz) is reduced significantly from the parent
10.6%. UVevis (CH2Cl2) lmax in nm (3
in Mꢁ1 cmꢁ1): 236 (16100);
297 (4800); 332 (2300); 387 (1700). 1H NMR (CDCl3)
d: 1.45e1.60
(m, metalated phosphine þ OCH2CH3); 4.59 (q, 7.2 Hz, OCH2). 13
C
{1H} NMR (CDCl3)
d
: 1.1 (d, J(PeH) ¼ 28 Hz, 1J(PteH) ¼ 554 Hz, CH2);
13.8 (s, OCH2CH3); 31.4 (J(PteH)
¼
31 Hz, CMe3); 32.9 (J
(PteH) ¼ 70 Hz); 37.2 (d, J(PeH) ¼ 12.5 Hz, CMe3); 56.7 (d, J
chloro-bridged complex, [Pt2(
influence of the bridging chalcogenolate ligand [29].
m
-Cl)2(CXP)2] due to strong trans
(PeH) ¼ 26 Hz, CMe2); 67.7 (s, OCH2); 236.5 (CS2). 31P{1H} NMR

N. Ghavale et al. / Journal of Organometallic Chemistry 695 (2010) 2296e2304
2299
Table 1
Crystallographic and structure refinement data for platinum complexes.
Complex
1
3$C6H6
8
9
11
Chemical formula
Formula weight
Crystal size (mm3)
Crystal system
C
36H62P2Pt2S2
C36H64N4P2Pt2
1005.03
0.1 ꢂ 0.2 ꢂ 0.2
Orthorhombic
P 212121
C17H31ClNPPt S
543.00
0.1 ꢂ 0.15 ꢂ 0.15
Monoclinic
P21/n
C38H62O2P2Pt2S2
1067.12
0.05 ꢂ 0.1 ꢂ 0.2
Monoclinic
P21/n
C18H40O2P2PtS2
609.65
0.1 ꢂ 0.15 ꢂ 0.15
Monoclinic
P21/n
1011.10
0.2 ꢂ 0.2 ꢂ 0.4
Monoclinic
P21/n
Space group
Unit cell dimensions
ꢀ
a (A)
18.927(7)
11.379(7)
18.783(7)
e
14.610(2)
30.513(13)
8.987(4)
90.00
90.00
90.00
4006(2)
1.666
4
7.084/1976
ꢁ10 ꢄ h ꢄ 18
0 ꢄ k ꢄ 39
ꢁ6 ꢄ l ꢄ 11
2.63 to 27.47
5578/3664
5599/0/383
0.0647/0.1421
0.1264/0.1758
1.056
9.0000(15)
29.590(3)
7.9900(17)
e
11.772(4)
10.600(3)
17.200(10)
e
8.7439(11)
14.050(2)
20.7000(19)
e
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(ꢀ)
(ꢀ)
(ꢀ)
102.19(3)
e
103.519(16)
e
109.51(4)
e
92.156(9)
e
3
ꢀ
Volume (A )
3954(3)
1.698
4
2068.9(6)
1.743
4
2023.1(14)
1.752
2
2541.2(6)
1.593
4
r
Z
m
calcd. (g cmꢁ3
)
(mmꢁ1)/F(000)
Limiting indices
7.277/1984
ꢁ24 ꢄ h ꢄ 24
0 ꢄ k ꢄ 14
ꢁ24 ꢄ l ꢄ 13
2.78 to 27.50
9050/6549
9050/0/397
0.0591/0.1896
0.0932/0.2204
1.052
7.087/1064
ꢁ11 ꢄ h ꢄ 6
0 ꢄ k ꢄ 38
ꢁ10 ꢄ l ꢄ 10
2.70 to 27.48
4647/3061
4647/0/208
0.0368/0.0861
0.0783/0.1002
1.020
7.120/1048
ꢁ14 ꢄ h ꢄ 15
0 ꢄ k ꢄ 13
ꢁ22 ꢄ l ꢄ 12
2.51 to 27.51
4654/3180
4654/0/216
0.0392/0.0963
0.0809/0.1148
0.938
5.821/1216
ꢁ11 ꢄ h ꢄ 11
ꢁ18 ꢄ k ꢄ 0
ꢁ26 ꢄ l ꢄ 15
2.50 to 27.49
5827/3916
5827/0/238
0.0464/0.1169
0.0894/0.1339
1.037
q
range of data collection (ꢀ)
Reflections collected/unique
Data/restraints/parameters
Final R1, uR2 indices
R1, uR2 (all data)
Goodness of fit on F2
The reactions of [Pt2(
dimethylpyrazole (dmpzH) in methanol in the presence of NaOH
m
-Cl)2(CXP)2] with pyrazole (pzH)/3,5-
been known to yield a mixture of cis and trans isomers of pyr-
azolate-bridged complexes, [Pt2R02( -NXN)2(PR3)2] [31]. The rela-
m
in 1:2:2
[Pt2(
M
ratio afforded bis(pyrazolate)-bridged complexes,
tive ratio of the two isomers varied from one preparation to
another and also varied from the relative concentration of the two
isomers in the parent chloro-bridged complexes [31]. The 31P{1H}
and 195Pt{1H} NMR spectra of 3 and 4 exhibited two sets of
resonances assignable to cis (minor, w5% (3); w24% (4)) and trans
(major, w95% (3); 76% (4)) isomers. The 195Pt NMR resonance for
m
-NXN)2(CXP)2] (NXN ¼ pz (3) and dmpz (4)). The NMR
spectra of these complexes reveal that a mixture of cis and trans
isomers is formed with the latter predominating in solution. Goel
et al. [30] however, isolated only the trans form. The reactions of
[Pt2R02(
m-Cl)2(PR3)2] with pyrazoles in the presence of a base have
Scheme 1.

2300
N. Ghavale et al. / Journal of Organometallic Chemistry 695 (2010) 2296e2304
Table 2
-SPh)2(But2PCMe2CH2)2]
ꢀ
ꢀ
Selected bond distances (A) and bond angles ( ) for [Pt2(
m
(1).
Pt(1)eP(1)
Pt(1)eC(8)
P(1)eC(7)
C(8)eC(7)
Pt(1)eS(1)
Pt(1)eS(2)
S(1)eC(1)
2.218(3)
2.097(10)
1.889(12)
1.563(16)
2.365(3)
2.440(3)
1.787(14)
Pt(2)eP(2)
Pt(2)eC(26)
P(2)eC(25)
C(26)eC(25)
Pt(2)eS(1)
Pt(2)eS(2)
S(2)eC(19)
2.232(3)
2.094(10)
1.873(12)
1.552(16)
2.366(3)
2.420(3)
1.786(12)
Fig. 1. 195Pt{1H} NMR spectrum of [Pt(S2COEt){CH2C(Me2)PBut2-C,P}] (10) in CDCl3.
Pt(1)/Pt(2)
3.269
P(1)ePt(1)eS(1)
P(1)ePt(1)eS(2)
S(1)ePt(1)eS(2)
Pt(1)eS(1)ePt(2)
C(8)ePt(1)eS(2)
C(8)ePt(1)eS(1)
C(8)ePt(1)eP(1)
C(1)eS(1)ePt(1)
C(19)eS(2)ePt(1)
C(7)eC(8)ePt(1)
C(7)eP(1)ePt(1)
C(8)eC(7)eP(1)
C(11)eP(1)ePt(1)
C(15)eP(1)ePt(1)
169.06(10)
108.22(10)
82.39(10)
87.41(10)
175.5(4)
99.1(3)
P(2)ePt(2)eS(1)
P(2)ePt(2)eS(2)
S(1)ePt(2)eS(2)
Pt(2)eS(2)ePt(1)
C(26)ePt(2)eS(2)
C(26)ePt(2)eS(1)
C(26)ePt(2)eP(2)
C(1)eS(1)ePt(2)
C(19)eS(2)ePt(2)
C(25)eC(26)ePt(2)
C(25)eP(2)ePt(2)
C(26)eC(25)eP(2)
C(29)eP(2)ePt(2)
C(33)eP(2)ePt(2)
170.07(10)
106.85(11)
82.82(11)
84.54(10)
175.2(4)
100.7(3)
69.8(3)
112.0(4)
109.8(4)
102.5(7)
88.0(4)
the cis form appeared at lower frequency than the trans isomer.
The magnitude of 1J(PteP) is reduced significantly from the one
observed for the parent chloro-bridged complex. Similar reduction
in coupling constant in pyrazolate-bridged platinum complexes
has been reported [31,32].
70.1(3)
108.3(4)
107.5(3)
103.7(7)
89.3(4)
91.4(7)
121.1(5)
110.0(5)
The reactions of [Pt2(m
-Cl)2(PXC)2] with anionic three-atom
ligands gave different products depending on the nature of the
donor atoms and the ligand bite. Reaction with silver acetate yiel-
92.2(7)
111.4(4)
121.3(4)
ded an acetato-bridged complex, [Pt2(m
-OAc)2(CXP)2] (5). The IR
spectrum displayed carbonyl stretching at 1560 cmꢁ1 indicating
bridging acetate group. The carbonyl stretching of bridging acetate
group has been reported at 1575 cmꢁ1 and 1570 cmꢁ1 for [Pt2(
m-
OAc)2(C8H12OMe)2] [33] and [Pt2Cl2(m-OAc)2(PEt3)2] [34], respec-
Treatment of [Pt2(m
-Cl)2(CXP)2] with one equivalent of Pb(Spy)2
tively. The 1H and 13C{1H} NMR spectra showed a singlet for the
methyl group of acetate ligand suggesting sym-trans configuration.
The 31P NMR spectrum displayed a singlet with 1J(PteP) of 3866 Hz
indicating binuclear complex. Similar 195Pt NMR spectrum showed
a doublet at ꢁ3507 ppm, which is deshielded with reference to the
chloro-bridged parent complex. Recently reactions of the chloro-
bridged platinum complex, containing five-membered metalated
gave a product which displayed four doublets at
d
ꢁ3713 (1J
(PteP) ¼ 2950 Hz); ꢁ3837 (1J(PteP) ¼ 3104 Hz); ꢁ3853 (1J
(PteP) ¼ 3091 Hz) and ꢁ4122 (1J(PteP) ¼ 2968 Hz; constitute
w70%) in the 195Pt{1H} NMR spectrum. The magnitude of 1J(PteP)
coupling constants suggests that all the four species contain thio-
late bridges. The pyS ligand has been known to bridge two metal
atoms either through sulfur (monodentate) or via N, S-bridging
atoms [36]. The observed four doublets may be assigned to the cis
and trans isomers of the two different bridging modes of the pyS
ligand. Attempts to separate these isomers either by recrystalliza-
tion or by column chromatography were unsuccessful. It is worth
phosphine, [Pt2(
m
-Cl)2(CXP0)2] (CXP0 ¼ CMe2C6H4(o)PBut2-C,P) with
silver carboxylates have been studied [35]. With silver acetate
a monomeric complex, [Pt(CXP0)(OAc)], containing chelated acetate
(from X-ray), is formed, but with silver trifluoroacetate both
monomeric (with chelated O2CCF3) and dimeric (with bridging
O2CCF3) species exist in a dynamic equilibrium in solution.
However, in the solid-state only dimeric complex (from X-ray) is
isolated [35].
noting that the reaction of [Pd2(m-Cl)2(Me2NCH2C6H4(o)-N,C)2]
with pySH yields a binuclear complex stabilized by SN bridges [11],
while the reaction of [Pt2(m-Cl)2(ppy)2] (ppy ¼ 2-C6H4eC5H4N)
Treatment of [Pt2(m
-Cl)2(CXP)2] with silver salts of di(p-tolyl)
triazine and diphenylacetamidine afforded binuclear complexes,
[Pt2(ArNXNAr)2(CXP)2] (Ar/X ¼ tol/N (6) and Ph/CMe (7)). The 31P
and 195Pt NMR spectra showed a single set of resonances indicative
of the formation of only one isomer. The presence of J(PteP0)
coupling (190 Hz) in the 195Pt spectra is suggestive of binuclear
formulation.
Table 3
-pz)2(But2PCMe2CH2)2]$
ꢀ
ꢀ
Selected bond distances (A) and bond angles ( ) for [Pt2(
C6H6 (3$C6H6).
m
N(1)ePt(1)
N(4)ePt(1)
P(1)ePt(1)
C(20)ePt(1)
N(1)eN(2)
C(17)eP(1)
C(11)eP(1)
C(7)eP(1)
2.099(17)
2.11(3)
2.216(6)
2.01(4)
1.38(3)
1.87(3)
1.87(3)
1.90(3)
1.55(4)
N(2)ePt(2)
N(3)ePt(2)
P(2)ePt(2)
C(32)ePt(2)
N(3)eN(4)
P(2)eC(29)
P(2)eC(21)
P(2)eC(25)
C(29)eC(32)
2.10(2)
2.088(17)
2.228(5)
2.01(3)
1.32(3)
1.88(3)
1.86(2)
1.85(3)
1.55(3)
C(17)eC(20)
Pt(1)/Pt(2)
3.547
N(2)eN(1)ePt(1)
N(3)eN(4)ePt(1)
N(1)ePt(1)eN(4)
C(20)ePt(1)eN(1)
C(20)ePt(1)eN(4)
N(4)ePt(1)eP(1)
N(1)ePt(1)eP(1)
C(20)ePt(1)eP(1)
C(17)eP(1)ePt(1)
C(11)eP(1)ePt(1)
C(7)eP(1)ePt(1)
C(17)eC(20)ePt(1)
C(1)eN(1)ePt(1)
C(6)eN(4)ePt(1)
120.4(14)
119.7(15)
89.3(7)
N(1)eN(2)ePt(2)
N(4)eN(3)ePt(2)
N(2)ePt(2)eN(3)
C(32)ePt(2)eN(3)
C(32)ePt(2)eN(2)
N(2)ePt(2)eP(2)
N(3)ePt(2)eP(2)
C(32)ePt(2)eP(2)
C(29)eP(2)ePt(2)
C(21)eP(2)ePt(2)
C(25)eP(2)ePt(2)
C(29)eC(32)ePt(2)
C(3)eN(2)ePt(2)
C(4)eN(3)ePt(2)
121.7(13)
124.1(16)
90.1(7)
94.8(8)
94.3(8)
173.9(9)
105.9(5)
164.6(5)
69.8(7)
85.8(10)
114.0(9)
121.1(8)
103(2)
173.2(11)
105.8(5)
163.9(6)
70.0(7)
87.5(7)
113.0(7)
121.2(9)
105.8(19)
134.8(18)
125.7(18)
129.4(18)
133.9(16)
Fig. 2. 195Pt{1H}NMR of [Pt{S2P(OPri)2}{CH2C(Me2)PBut2-C,P}] (11) in CDCl3.

N. Ghavale et al. / Journal of Organometallic Chemistry 695 (2010) 2296e2304
2301
Table 4
Table 6
t
i
t
ꢀ
ꢀ
ꢀ
ꢀ
Selected bond distances (A) and bond angles ( ) for [PtCl(Spy)(PBu 3)] (8).
Selected bond distances (A) and bond angles ( ) for [Pt(S2P{OPr }2)(Bu 2PCMe2CH2)]
(11).
Pt(1)eN(1)
Pt(1)eP(1)
Pt(1)eS(1)
Pt(1)eCl(1)
P(1)eC(6)
2.094(6)
2.3146(18)
2.331(2)
2.346(2)
1.921(10)
P(1)eC(10)
P(1)eC(14)
S(1)eC(1)
C(1)eN(1)
1.942(10)
1.919(8)
1.747(8)
1.358(9)
S(1)ePt(1)
S(2)ePt(1)
P(2)ePt(1)
C(18)ePt(1)
2.396(2)
2.440(2)
2.2129(19)
2.083(8)
P(1)eS(1)
P(1)eS(2)
O(1)eP(1)
O(2)eP(1)
2.002(3)
1.988(3)
1.572(6)
1.579(6)
N(1)ePt(1)eP(1)
N(1)ePt(1)eS(1)
P(1)ePt(1)eS(1)
N(1)ePt(1)eCl(1)
P(1)ePt(1)eCl(1)
S(1)ePt(1)eCl(1)
C(1)eS(1)ePt(1)
170.89(17)
69.14(18)
101.75(7)
87.93(19)
101.15(8)
156.89(9)
81.9(3)
C(1)eN(1)ePt(1)
C(5)eN(1)ePt(1)
C(6)eP(1)ePt(1)
C(10)eP(1)ePt(1)
C(14)eP(1)ePt(1)
N(1)eC(1)eS(1)
101.2(5)
137.0(5)
107.0(3)
111.4(3)
112.9(3)
107.8(5)
S(1)ePt(1)eS(2)
P(1)eS(1)ePt(1)
P(1)eS(2)ePt(1)
S(2)eP(1)eS(1)
O(1)eP(1)eS(1)
O(2)eP(1)eS(1)
O(1)eP(1)eS(2)
O(2)eP(1)eS(2)
82.39(8)
84.88(10)
84.01(10)
105.95(13)
114.1(3)
113.0(3)
115.0(3)
113.4(3)
C(18)ePt(1)eS(1)
P(2)ePt(1)eS(1)
C(18)ePt(1)eS(2)
P(2)ePt(1)eS(2)
C(11)eP(2)ePt(1)
C(7)eP(2)ePt(1)
C(15)eP(2)ePt(1)
C(15)eC(18)ePt(1)
C(18)ePt(1)eP(2)
99.3(2)
168.29(8)
177.9(2)
108.50(7)
121.9(3)
109.1(3)
88.4(3)
103.5(5)
69.9(2)
with Pb(Spy)2 readily afforded
Spy)2(ppy)2] [10].
a Pt(III) complex, [Pt2Cl2(m-
CXP group. The 195Pt NMR spectrum of 11 showed doublet of
apparently looking quartet, which may be merging of two trip-
lets due to the formation of binuclear species having cis and
trans isomers with very close chemical shifts (Fig. 2). However,
A different synthetic approach was attempted which involved
a reaction between [Pt2(
m
-Cl)2(CXP)2] and pySH in the presence of
pyridine as HCl scavenger. However, this reaction gave a mono-
nuclear complex [PtCl(Spy)(PBut3)] (8). The PBut3 seems to be
formed by the action of liberated HCl on metalated phosphine. The
31P and 195Pt NMR spectra showed a single set of resonances with
195Pt and 31P couplings in their respective spectra. This suggests
that only one isomeric species exists exclusively in solution. The 2-
mercaptopyridine complexes of palladium and platinum of
composition [MCl(Spy)(PR3)] have been described previously
[37e40]. Overall nuclearity (mono-/di-meric) of the resulting
complex is governed by the basicity of phosphine in these
complexes.
the solid-state structure (see later) revealed
a monomeric
species with chelating 1,1-dithiolate group. The 1,1-dithiolate
complexes of palladium and platinum with metalated nitrogen
and phosphorus ligands have been described in literature
[10,41]. In all these complexes (e.g. [Pd(Me2NCH2C6H4(o)-N,C)
{S2P(OPri)2}] (CePdeN ¼ 81.7(2)ꢀ; SePdeS ¼ 83.24(5)ꢀ) [41]; [Pt
(S2CNMe2){CH2C6H4(o)Ptol2-C,P}]
(PePteC
¼
84.2(2)ꢀ;
SePteS ¼ 74.1(1)ꢀ) [42]; [Pt{S2P(OPri)2}(ppy)] (CePteN ¼ 82.1
(5)ꢀ; SePteS ¼ 82.80(17)ꢀ [10])) the solid-state structure prevails
in solution. These complexes have four-(dithiolate) and five-
(metalated ligand) membered chelate rings. However, in 10 and
11 there are two four-membered chelate rings (dithiolate and
CXP). It is likely that to relieve strain of the two four-membered
rings (PePteC and SePteS angles of 69.9(2)ꢀ and 82.39(8)ꢀ,
respectively in 11) the dithiolate adopts a bridging position (e.g.
in 9, PteSePt ¼ 97.21(7)ꢀ). Bridging mode of dithiophosphate
ligand is well documented in literature [43].
The reaction between [Pt2(m
-Cl)2(CXP)2] and AgSCOPh in
dichloromethane afforded an orange binuclear complex, [Pt2(m-
SCOPh)2(CXP)2] (9). The 31P and 195Pt NMR spectra showed two sets
of resonances with similar 1J(PteP) values. The most shielded
resonances due to major species (65%) have been attributed to the
sym trans isomer while the other resonance due to minor species
(35%) has been assigned to the cis form.
The reactions of [Pt2(m
-Cl)2(CXP)2] with sodium salt of eth-
ylxanthate and ammonium salt of diisopropyldithiophosphate
yielded 1,10-dithiolate complexes, [Pt(SXS)(CXP)] (SXS ¼ S2COEt
(10) and S2P{OPri}2 (11)). The 1J(PePt) value of 3067 Hz in 31P
NMR spectra of 10 indicated the formation of binuclear species.
The 195Pt NMR spectra displayed a doublet of triplet indicating
the presence of cis and trans isomers in equal ratio (Fig. 1). The
triplet pattern may be explained due to the merging of two
doublets of cis and trans isomers due to J(PteP0) coupling. The
31P NMR spectrum of 11 displayed two sets of peaks. The
multiplet at higher frequency with 1J(PteP) ¼ 3250 Hz is due to
Table 5
Selected bond distances (A) and bond angles (ꢀ) for [Pt2(
m
-SCOPh)2(But2PC-
ꢀ
Me2CH2)2] (9).
Pt(1)eS(1)
Pt(1)eS(1)
Pt(1)eP(1)
Pt(1)eC(19)
S(1)eC(1)
2.376(2)
2.445(2)
2.238(2)
2.072(8)
1.800(9)
P(1)eC(8)
P(1)eC(12)
P(1)eC(16)
O(1)eC(1)
1.898(9)
1.882(9)
1.887(9)
1.199(10)
Pt(1)/Pt(2)
3.617
S(1)ePt(1)eS(1)
C(19)ePt(1)eS(1)
C(19)ePt(1)eP(1)
P(1)ePt(1)eS(1)
C(19)ePt(1)eS(1)
P(1)ePt(1)eS(1)
C(1)eS(1)ePt(1)
C(1)eS(1)ePt(1)
82.79(7)
97.3(2)
70.1(2)
165.70(8)
170.1(3)
110.79(7)
112.5(3)
112.6(3)
Pt(1)eS(1)ePt(1)
C(12)eP(1)ePt(1)
C(16)eP(1)ePt(1)
C(8)eP(1)ePt(1)
O(1)eC(1)eS(1)
C(2)eC(1)eS(1)
C(16)eC(19)ePt(1)
O(1)eC(1)eC(2)
97.21(7)
110.6(3)
87.1(3)
122.8(3)
118.8(8)
119.9(6)
103.0(5)
121.2(8)
Fig. 3. ORTEP diagram of [Pt2(
scheme (ellipsoids are drawn with 50% probability).
m
-SPh)2(But2PCMe2CH2)2] (1) with atomic numbering

2302
N. Ghavale et al. / Journal of Organometallic Chemistry 695 (2010) 2296e2304
Fig. 4. ORTEP diagram of [Pt2(
m
-pz)2(But2PCMe2CH2)2]$C6H6 (3) with atomic numbering scheme (ellipsoids are drawn with 50% probability).
3.2. Crystal structures
interactions. As expected, the PtePt separation in bent structures
ꢀ
(e.g. 1; 3.269 A) is shorter than the one observed in planar struc-
Crystal and molecular structures of [Pt2(
m
-SPh)2(CXP)2] (1),
-SCOPh)2(CXP)2]
tures (e.g. 9, 3.617 A).
ꢀ
[Pt2(m
-pz)2(CXP)2] (3), [PtCl(Spy)(PBut3)] (8) [Pt2(
m
The structural analysis of 1 supports the conclusions drawn
from NMR spectroscopic data. The molecule adopts a sym-cis
configuration with non-planar ‘Pt2S2’ ring (hinge angle 51.74ꢀ)
(Fig. 3). There are distinctly two types of PteS distances, the one
trans to P atom is shorter than those trans to C atom of the meta-
lated phosphine ligand reflecting stronger trans influence of the
latter. The PteS distances are well within the range reported for
(9) and [Pt{S2P(OPri)2}(CXP)] (11) have been established by single
crystal X-ray diffraction analyses. Selected bond lengths and angles
are summarized in Tables 2e6 and ORTEP drawings with crystal-
lographic numbering scheme are shown in Figs. 3e7. The PteP
ꢀ
ꢀ
(2.212e2.238 A) and PteC (2.01e2.097 A) bond distances and
PePteC (w70ꢀ) angle of metalated tri-t-butylphosphine are similar
to those observed in other platinum(II) complexes containing this
[Pt2Ph2(m-SPh)2(PMe2Ph)2] [47], [Pt2Cl2(m-SEt)2(PPr3)2] [48] and
and related ligands, e.g. [Pt2(
m
-Cl)2(CXP)2] [44], [Pt2(
m-
[Pt2I2(
m
-SCH2CH2CMe¼CH2)2(PPh3)2] [49]. The SPh groups adopt
Cl)2{CH2CMe2CH2PBut2eC,P}2] [45], [Pt2(
m
-dmpz)2(CXP)2] [30] and
an anti conformation. The PteSePt angles (84.54(10), 87.41 (10)ꢀ)
are as expected [47e49].
[Pt(Cp)(CXP)(PPh3)] [46]. The four-membered chelate ring,
“PtePeCeC” is non-planar in these complexes. The Pt/Pt
distances of 3.269e3.617 A are too long to support any bonding
The complex [Pt2(m
-pz)2(CXP)2] (3) crystallizes with a molecule
ꢀ
of benzene and exists in a trans configuration. The two planar
pyrazolate groups bridges two platinum atoms (Fig. 4). The six-
membered Pt2N4 ring has a boat conformation as observed for
pyrazolate-bridged binuclear platinum complexes, such as
[Pt2Cl2(m-dmpz)2(PMePh2)2] [32], [Pt2(m
-dmpz)2(CXP)2] [30],
Fig. 5. ORTEP diagram of [PtCl(Spy)(PBut3)] (8) with atomic numbering scheme
(ellipsoids are drawn with 50% probability).
Fig. 6. ORTEP diagram of [Pt2(
scheme (ellipsoids are drawn with 50% probability).
m
-SCOPh)2(But2PCMe2CH2)2] (9) with atomic numbering

N. Ghavale et al. / Journal of Organometallic Chemistry 695 (2010) 2296e2304
2303
metalated phosphine and slightly asymmetrically chelated dithio-
phosphate ligand (Fig. 7). Interestingly dithiophosphate ligand in
[Pt(ppy){S2P(OPri)2}] is symmetrically chelated. The two PteS
distances in 11 are similar to those reported in [Pt(ppy){S2P(OPri)2}]
[10], [Pt{S2P(OEt)2}2(PPh3)] [55]. The structural features, the PeS
distances and the acute SePteS angle (82.39ꢀ), of the dithiophos-
phate group are in conformity with the complexes containing
chelating dithiophosphate ligand as in [Pt(ppy){S2P(OPri)2}] [10],
[Pt{S2P(OEt)2}2(PPh3)] [55] and [PtMe{S2P(OPri)2}(AsPh3)] [56].
4. Conclusions
Reactions of [Pt2(m
-Cl)2(CXP)2] with various ligands differing in
bite size and denticity yield a variety of complexes which could be
characterized by NMR spectroscopy. Although the parent complex
[Pt2(m
-Cl)2(CXP)2] exists as a mixture of cis and trans isomers in
solution, the resulting binuclear complexes tend to adopt a cis
configuration with strong trans influencing single atom bridging
ligands (e.g. EPh). With two- and three- atom anionic ligands trans
configuration is preferred even if a cis isomer is formed it exists as
a minor species. The strain in four-membered PXC ring tends to
influence overall structure in solution as in the case of 11.
Fig. 7. ORTEP diagram of [Pt(S2P{OPri}2)(But2PCMe2CH2)] (11) with atomic numbering
scheme (ellipsoids are drawn with 50% probability).
[Pt2(m-pz)2(thpy)2] (thpy ¼ C4H2SeC5H4N) [50], [Pt2(m-pz)2(ppy)2]
[10]. The two mean square planes of platinum atom inclined with
the base of the boat i.e. the plane containing the four N atoms by
47.59ꢀ (Pt1) and 40.35ꢀ (Pt2). There are two dissimilar PteN
distances owing to the different trans influence of phosphine and
the metalated carbon atom. Thus, the bonds trans to the phosphine
ligands are slightly shorter than those trans to the carbon atom. All
the four PteN distances are, however, in conformity with those
Acknowledgements
We thank Drs. T. Mukherjee and D. Das for encouragement of
this work. We are thankful to the Chemistry Department, IIT
Bombay, Mumbai for providing microanalysis of the complexes.
One of the authors (NG) is thankful to DAE for the award of a Senior
Research Fellowship.
reported
for
pyrazolate-bridged
platinum
complexes
ꢀ
[10,30,32,50,51]. The Pt/Pt separation (3.547 A) is the longest
reported so far in binuclear pyrazolate-bridged platinum
complexes (2.8343e3.3763 A) [10,32,50,51]. This is due to the
Appendix A. Supplementary material
ꢀ
outward bending of the two metal planes of platinum atoms to
CCDC Nos. 775651 (for 1), 775652 (for 3), 775653 (for 8), 775654
(for 9) and 775655 (for 11); contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
minimize the steric repulsion of bulkier But group.
The single crystal X-ray analysis of 5 reveals a highly disordered
dimeric acetate-bridged sym-trans structure with Pt/Pt separa-
ꢀ
tion of 3.369 A. The structure could not be refined completely and
hence, results are not discussed here (Supplementary material).
The complex [PtCl(Spy)(PBut3)] (8) is a discrete monomer with
the platinum atom acquiring a distorted square planar coordination
environment defined by P, Cl, N, S donor atoms (Fig. 5). The neutral
donors (P and N) occupy mutually trans positions. The Spy forms
a four-membered chelate ring with platinum. The platinum square
plane, chelate ring and the pyridyl ring are co-planar. The PteS,
PteN and PteCl distances are well within the ranges reported for
platinum complexes [10,32,47,52]. The acute NePteS angle (69.14
(18)ꢀ) reflects the small bite of the Spy ligand. This angle can be
compared with those complexes containing chelating Spy ligand,
e.g. [PdCl(Spy)(PPh3)] (73.9 and 67.3ꢀ) [37], [Ru(Spy)2(L)(PPh3)]
(L ¼ CO, PPh3) (66.6e67.8ꢀ) [53,54].
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2010.07.005.
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