Metal-heterocyclic thione interactions. 12. Heterocyclic 2-thiolates of platinum(II) and palladium(II): The crystal structures of first examples of cis- [M(η1-S-pyridine-2-thiolato)2(L-L)] {M = Pt, Pd, L-L = 1,2-bis(diphenylphosphino)ethane; M = Pt, L-L = 1,2-bis(diphenylphosphino)ethene} complexes

Article abstract of DOI:10.1016/S0277-5387(00)00329-6

A series of platinum(II) complexes of stoichiometry cis-[Pt(η¹-S-C₅H₄NS)₂(L-L)] were obtained from the reactions of platinum tetra-chloride with pyridine-2-thione (C₅H₅NS) in the presence of Et₃N base in an ethanol-benzene mixture followed by the addition of bis(tertiary phosphines), viz. {Ph₂P-X-PPh₂}, or phosphine chalcogenides {Ph₂P-CH₂-P(E)Ph₂} {X(L-L) = (CH₂)₂(dppe) (1), CH=CH(dppen) (2), (CH₂)₃(dppp) (3), (CH₂)₄(dppb) (4), E = S, dppmPS (5), E = Se, dppmPSe (6)}. Palladium(II) complexes, viz. [Pd(η¹-S-C₅H₄NS)₂(L-L)] {L-L = dppm (X = CH₂) (7), dppe (8), dppp (9), dppmPS (10), dppmPSe (11)}, were prepared by reacting [PdCl₂(diphosphines)] suspended in ethanol with C₅H₅NS in the presence of aqueous NaOH. All these compounds have been characterised with the help of analytical data [IR, far-IR, NMR (¹H, ¹³C, ³¹P) spectroscopy] and X-ray crystallography (for compounds 1, 2 and 8). The geometry about each metal centre is distorted square planar with trans bond angles of: compound 1, P-Pt-S, 170.31 (11), 173.18(10)°; compound 2, P-Pt-S, 168.97(5), 171.43(5)°; compound 8, P-Pd-S, 170.78(8), 171.83(8)°. The bite angles P(1)-M-P(2) and angles trans to bite angles, S(1)-M-S(2), are, respectively: compound 1, 85.68(11), 82.69(11)°; compound 2, 86.65(5), 84.01(6)°; compound 8, 85.19(8), 83.90(7)°. The dppe complexes (1 and 8) are isomorphous, monoclinic with space group C2/c, whereas the dppen complex is triclinic. These compounds represent the first examples of an interesting series of cis-platinum(II) and -palladium(II) derivatives of pyridine-2-thione containing chelating diphosphines and pendant pyridyl groups. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(00)00329-6

www.elsevier.nl/locate/poly
Polyhedron 19 (2000) 899–906
Metal–heterocyclic thione interactions.
12. Heterocyclic 2-thiolates of platinum(II) and palladium(II):
the crystal structures of first examples of cis-[M(h1-S-pyridine-2-
thiolato)2(L-L)] {MsPt, Pd, L-Ls1,2-bis(diphenylphosphino)ethane;
MsPt, L-Ls1,2-bis(diphenylphosphino)ethene} complexes
a
a
b
Tarlok S. Lobana a, , Renu Verma , Geeta Hundal , Alfonso Castineiras
*
a Department of Chemistry, Guru Nanak Dev University, Amritsar-143 005, India
b Departamento de Quimica Inorganica, Universidade de Santiago de Compostela, 15706-Santiago, Spain
Received 24 August 1999; accepted 4 February 2000
Abstract
A series of platinum(II) complexes of stoichiometry cis-[Pt(h1-S-C5H4NS)2(L-L)] were obtained from the reactions of platinum tetra-
chloride with pyridine-2-thione (C5H5NS) in the presence of Et3N base in an ethanol–benzene mixture followed by the addition of bis(tertiary
phosphines), viz. {Ph2P–X–PPh2}, or phosphine chalcogenides {Ph2P–CH2–P(E)Ph2} {X(L-L)s(CH2)2(dppe) (1), CH_CH(dppen)
(2), (CH2)3(dppp) (3), (CH2)4(dppb) (4), EsS, dppmPS (5), EsSe, dppmPSe (6)}. Palladium(II) complexes, viz. [Pd(h1-S-
C5H4NS)2(L-L)] {L-Lsdppm (XsCH2) (7), dppe (8), dppp (9), dppmPS (10), dppmPSe (11)}, were prepared by reacting
[PdCl2(diphosphines)] suspended in ethanol with C5H5NS in the presence of aqueous NaOH. All these compounds have been characterised
with the help of analytical data [IR, far-IR, NMR (1H, 13C, 31P) spectroscopy] and X-ray crystallography (for compounds 1, 2 and 8). The
geometry about each metal centre is distorted square planar with trans bond angles of: compound 1, P–Pt–S, 170.31(11), 173.18(10)8;
compound 2, P–Pt–S, 168.97(5), 171.43(5)8; compound 8, P–Pd–S, 170.78(8), 171.83(8)8. The bite angles P(1)–M–P(2) and angles
trans to bite angles, S(1)–M–S(2), are, respectively: compound 1, 85.68(11), 82.69(11)8; compound 2, 86.65(5), 84.01(6)8; compound
8, 85.19(8), 83.90(7)8. The dppe complexes (1 and 8) are isomorphous, monoclinic with space group C2/c, whereas the dppen complex is
triclinic.These compounds represent the first examples of an interesting series of cis-platinum(II) and -palladium(II) derivatives of pyridine-
2-thione containing chelating diphosphines and pendant pyridyl groups.
q2000 Elsevier Science Ltd All rights reserved.
Keywords: Bisphosphines; Heterocyclic thiones; Palladium(II) complexes; Platinum(II) complexes; Pyridyl
1. Introduction
ways of binding, notably terminal S-bonding and S-bridging
(in neutral form), whereas in anionic form the modes are
terminal S-bonding, S-bridging, N,S-chelating, N,S-bridg-
ing, N,S-chelation-cum-S-bridging, N,S-bridging-cum-S-
bridging [1–32].
The interactions of heavy metals such as platinum, gold
with N,S-donor atoms have been recognised for their anti-
carcinogenic properties with the potential to develop metal-
based drugs [1–4,33–36]. These drugs probably exert their
therapeutic action via interaction with DNA [33,34].
Recently, some papers involving platinum(II or IV) and
gold(I) complexes with tertiary phosphines as co-ligands
have been published [37–42]. Using pyridine-2-thione
(C5H5NS), only a few compounds of platinum(II) and
The interaction of heterocyclic thiones with metals has
been the subject of several investigations as these ligands
contain chemically active groups [–N(H)–C(_S)–l
–N_C(–SH)–] and are useful model compounds for sulfur-
containing analogues of purine and pyrimidine bases. Het-
erocylic 2-thiones bind to a metal in several ways, leading to
the formation of monomeric or polymeric complexes [1–4].
For example, the simplest prototype of heterocylic 2-thiones,
i.e. pyridine-2-thione (hereafter C5H5NS, I), has several
* Corresponding author. Tel.: q91-183-257604; fax: q91-183-258820;
e-mail: tarlok@angelfire.com
0277-5387/00/$ - see front matter q2000 Elsevier Science Ltd All rights reserved.
PII S0277-5387(00)00329-6
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palladium(II) with tertiary phosphines (R3P) have been
reported: namely, monomeric [Pt(h2-N,S-C5H4NS)-
(PPh3)2]PF6 [43], trans-[Pt(h1-S-C5H4NS)2(PPh3)2]
[21], [PdCl(h2-N,S-C5H4NS)(PPh3)] [44] and dimeric
[PdCl(h2-N,S-C5H4NS)(PMe3)]2 [45]. There is no report
of these metals containing bis-tertiary phosphines and pyri-
dine-2-thione (C5H5NS). Among the metals under discus-
sion, trans-[Pt(h1-S-C5H4NS)2(PPh3)2] [21] was the first
compound reported, by Lobana et al. [21], containing a pen-
dant pyridyl group in the trans position. In this paper, we
report first examples of platinum(II)andpalladium(II)com-
plexes containing chelating bisphosphines(II) and pendant
pyridyl groups in the cis position; these compounds may act
as potential precursors for polymeric complexes [46].
2.2. Platinum complexes
2.2.1. cis-[Pt(h1-S-C5H4NS)2(dppe)] (1)
To a solution of C5H5NS (0.07 g, 0.60 mmol) in 20 ml of
benzene containing 2 ml of Et3N base was added dropwise a
solution ofPtCl4 (0.100 g, 0.30 mmol)in20mlofdryethanol
under magnetic stirring, followed by the addition of solid
dppm (0.120 g, 0.30 mmol) when a clear solution formed,
and was stirred overnight (24 h). The white salt of
Et3NHqCly formed was separated by filtration and slow
evaporation of the filtrate gave a light yellow complex. Yield,
80%; m.p., 219–2208C. Anal. Found: C, 52.8; H, 3.90; N,
3.24. Required for C36H32N2S2P2Pt: C, 53.1; H, 3.93; N,
3.44%. IR (KBr, cmy1): 1550s, 1445s, 1415s, 1120s (nC–
S), 1095sh (nP–C), 1110s, 820s, 720s, 698vs, 540s, 405w
(nPt–P), 360w (nPt–S). NMR (CDCl3, d ppm, J, Hz): 1H,
8.47d (J5, 4.8, H6), 7.13m (H3), 6.86m (H4), 6.41m (H5),
2.27sb (–CH2–), 7.65m (Ph–P); 13C, 166.3, 159.0 (C2),
149.6, 147.8 (C6), 137.4, 133.5 (C4), 127.4, 121.1 (C5),
119.7, 116.8 (C3), 29.7 (–CH2), 131.2 (i-C), 133.5 (o-C),
128.6 (m-C and p-C); 31P, 45.5 (JP-Pt, 2968.2 Hz). Coordi-
nation shift, DdP 58.2 ppm. The crystals for X-ray study were
grown from a benzene–ethanol mixture (1:1, v/v). Com-
pounds 2–5 were prepared similarly.
2.2.2. cis-[Pt(h1-S-C5H4NS)2(dppen)] (2)
Yield, 80%; m.p., 218–2208C. Anal. Found: C, 53.3; H,
3.62; N, 3.70. Required for C36H30N2S2P2Pt: C, 53.3; H, 3.69;
N, 3.45%. IR (KBr, cmy1): 1580s, 1560s, 1435s, 1405s,
1195s, 1130s (nC–S), 1110s, 1095sh (nP–C), 1025w, 750s,
725s, 700vs, 560s, 540s, 415w (nPt–P), 350w (nPt–S).
NMR (CDCl3, d ppm, J, Hz): 1H, 8.48d (J5, 4.6, H6), 7.12m
(H3), 6.94m (H4), 6.53m (H5), 7.56m (Ph–P), 2.01sb
(–CH_CH–); 13C, 165.8 (C2), 147.3 (C6), 133.9 (C4),
127.6 (C5), 117.0 (C3), 145.4 (–CH_CH–), 132.4 (i-C),
133.3 (JC-P, 10.4, o-C), 126.8 (m-C), 131.3 (p-C); 31P, 53.5
(JP-Pt, 2958.5 Hz), 53.9 (JP-Pt, 2969.4 Hz). Coordination
shift, DdP 77.1 ppm. The crystals for X-ray study weregrown
from benzene–ethanol mixture (1:1, v/v).
2. Experimental
2.1. General materials
Platinum tetrachloride was procured from M/s Central
Drug House Pvt. (Bombay). cis-1,2-Bis(diphenylphos-
phino)ethene (Ph2PCH_CHPPh2, dppen), bis(diphenyl-
phosphino)methane (Ph2PCH2PPh2, dppm) and bis(di-
phenylphosphino)propane {Ph2P(CH2)3PPh2, dppp} were
procured from Aldrich. 1,2-Bis(diphenylphosphino)ethane
{Ph2P(CH2)2PPh2, dppe} and 1,4-bis(diphenylphosphino)-
butane {Ph2P(CH2)4PPh2, dppb} were prepared by lithiation
of PPh3 in dry tetrahydrofuran followed by reaction with 1,2-
dichloroethane or 1,4-dihalobutane as reported earlier [15].
2-Hydroxypyridine was procured from M/s Sisco Labora-
tories (Bombay), and pyridine-2-thione was then prepared
from it by treatment with P4S5 at 140–1458C, as reported
earlier [5]. The monosulfide (or selenide) of dppm was
prepared by reacting dppm with sulfur powder (or selenium
metal) in 1:1 ratio in dry benzene [6]. The starting materials,
PdCl2(L-L), were prepared by reacting PdCl2 solutions in
CH3CN with suitable bisphosphines [7].
2.2.3. cis-[Pt(h1-S-C5H4NS)2(dppp)] (3)
Yield, 75%; m.p., 224–2268C. Anal. Found: C, 53.2; H,
3.90; N, 3.20. Required for C37H34N2S2P2Pt: C, 53.7; H, 4.11;
N, 3.40%. IR (KBr, cmy1): 1430s, 1170s, 1120s (nC–S),
1100m (nP–C), 690s (nPh), 675s, 625m, 560m. NMR
(CDCl3, d ppm, J, Hz): 1H, 8.48d (J5, 4.8, H6), 7.69t (J3,5
,
7.7, H4), 7.45d (J4, 7.0, H3), 7.12t (J4,6, 3.9, H5), 1.42t
(–CH2–), 7.4–7.7m (Ph–P); 13C, 158.9 (C2), 149.5 (C6),
137.3 (C4), 121.1 (C5), 119.7 (C3), 29.3 (–CH2–), 133.6
(i-C), 131.7 (o-C), 128.5 (m-C), 130.7 (p-C).
2.2.4. cis-[Pt(h1-S-C5H4NS)2(dppb)] (4)
Yield, 78%; m.p., 230–2328C. Anal. Found: C, 54.7; H,
4.06; N, 3.73. Required for C38H36N2S2P2Pt: C, 54.22; H,
4.28; N, 3.33%. IR (KBr, cmy1): 1555m, 1440s, 1420m,
1175s, 1115m (nC–S), 1100sh (nP–C), 1030w, 1000m,
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901
840m, 740s, 690s, 560s, 510s, 415w (nPt–P), 340w (nPt–
690s (nPh) 535s, 490m, 440m, 400w (nPd–P), 350m (nPd–
1
1
S). NMR (CDCl3, d ppm, J, Hz): H, 8.47d (J5, 4.2, H6),
S). NMR (CDCl3, d ppm, J, Hz): H, 7.83m (H6), 6.79td
7.69t (J3,5, 5.7, H4), 7.46d (J4, 7.2, H3), 7.11t (J4,6, 4.0, H5),
1.41t (–CH2–), 7.63m (Ph–P); 13C, –, 149.6 (C6), 137.4
(C4), 121.1 (C5), 119.8 (C3), 29.7 (–CH2–), 131.8 (i-C),
130.7 (o-C), 128.4 (m-C and p-C).
(J3,5, 7.55, J6, 1.8, H4), 7.07d (J4, 8.0, H3), 6.44t (J4,6, 6.1,
H5), 2.32t (–CH2–), 7.32–7.79m (Ph–P); 13C, 168.5 (C2),
147.4 (C6), 133.2 (C4), 127.1 (C5), 116.0 (C3), 28.6
(–CH2), 129.6 (i-C), 133.6 (o-C), 128.4 (m-C), 131.0 (p-
C). The crystals for X-ray study were grown from ethanol.
2.2.5. cis-[Pt(h1-S-C5H4NS)2(dppmPS)] (5)
Yield, 75%; m.p., 128–1308C. Anal. Found: C, 50.28; H,
3.80; N, 3.50. Required for C35H30N2S3P2Pt: C, 50.48; H,
3.60; N, 3.36%. IR (KBr, cmy1): 1472m, 1435s, 1420s,
1115sh (nC–S), 1090s (nP–C), 730s, 680m, 610sh, 500m,
610w (nP–S), 405w (nPt–P), 355w (nPt–S). NMR
(CDCl3, d ppm, J, Hz): 1H, 8.47d (J5, 4.8, H6), 7.36m (H4),
7.62d (J4, 4.2, H3), 7.1m (H5), 3.11q (–CH2–), 7.56m (Ph–
P); 13C, 159.0 (C2), 149.4 (C6), 137.3 (C4), 121.0 (C5),
119.7 (C3), 29.5 (–CH2–), 131.5 (i-C), 130.7 (o-C), 128.2
(m-C and p-C).
2.3.3. cis-[Pd(h1-S-C5H4NS)2(dppp)] (9)
Yield, 72%; m.p., 128–1308C. Anal. Found: C, 58.9; H,
4.90; N, 3.40. Required for C37H34N2S2P2Pd: C, 60.1; H,
4.60; N, 3.70%. IR (KBr, cmy1): 1570s, 1440s, 1410w,
1180w, 1125m (nC–S), 1105m (nP–C), 830w, 750m, 725w,
700s, 545s, 510s, 420w (nPd–P), 390w, 365w (nPd–S).
1
NMR (CDCl3, d ppm, J, Hz): H, 8.40d (J5, 8.0, H6), –,
6.92d (J4, 7.0, H3), 6.65t (J4,6 6.4, H5), 2.40t (–CH2–), 7.5m
(Ph–P); 13C, 172.9 (C2), 146.5 (C6), 136.2 (C4), 126.7
(C5), 117.0 (C3), 29.0 (–CH2–), 132.9 (i-C), 133.5 (o-C),
128.5 (m-C), 130.7 (p-C).
2.2.6. cis-[Pt(h1-S-C5H4NS)2(dppmPSe)] (6)
Yield, 78%; m.p., 146–1498C. Anal. Found: C, 47.4; H,
3.30; N, 3.50. Required for C35H30N2S2P2SePt: C, 47.8; H,
3.41; N, 3.19%. IR (KBr, cmy1): 1560s, 1470m, 1430s,
1115w (nC–S), 1090s (nP–C), 1030m, 860w, 735m, 680m,
500sb, 490s (nP–Se), 405w (nPt–P), 355w (nPt–S). NMR
(CDCl3, d ppm, J, Hz): 1H, 8.47d (J5, 4.0, H6), –, 7.60d (J4,
2.0, H3,), 7.10m (H5), 3.06q (–CH2–), 7.57m (Ph–P); 13C,
–, 149.5 (C6), 137.3 (C4), 121.0 (C5), 119.7 (C3), 29.6
(–CH2–), 132.4 (i-C), 131.6 (o-C), 128.2 (m-C), 130.5
(p-C).
2.3.4. cis-[Pd(h1-S-C5H4NS)2(dppmPS)] (10)
Yield, 70%; m.p., 150–1528C. Anal. Found: C, 56.1; H,
3.90; N, 3.70. Required for C35H30N2S3P2Pd: C, 56.6; H,
4.04; N, 3.77%. IR (KBr, cmy1): 1570w, 1475w, 1430s,
1185w, 1115s (nC–S), 1095m (nP–C), 995m, 780w, 735s,
680s, 610w (nP–S) 550m, 510s, 425sh (nPd–P). NMR
(CDCl3, d ppm, J, Hz): 1H, 8.54d (J5, 5.6, H6), –, 7.18d (J4,
5.0, H3), 6.73t (J4,6, 7.0, H5), 3.1q (–CH2–), 7.6m (Ph–P);
13C, –, 146.5 (C6), 137.2 (C4), 122.0 (C5), 116.5 (C3), 29.7
(–CH2–), 133.7(i-C), 131.9 (o-C), 128.5 (m-C), 130.8
(p-C).
2.3. Palladium complexes
2.3.5. cis-[Pd(h1-S-C5H4NS)2(dppmPSe)] (11)
2.3.1. cis-[Pd(h1-S-C5H4NS)2(dppm)] (7)
Yield, 70%; m.p., 170–1728C. Anal. Found: C, 53.4; H,
3.60; N, 3.70. Required for C35H30N2S2P2SePd: C, 53.2; H,
3.80; N, 3.55%. IR (KBr, cmy1): 1570m, 1490m, 1440s,
1410m, 1190, 1120m (nC–S), 1085sh (nP–C), 1030w,
1000w, 775sh, 740s, 700s, 490s (nP–Se), 425sh (nPd–P),
360w (nPd–S). NMR (CDCl3, d ppm): 13C, 167.5 (C2),
147.1 (C6), 136.4 (C4), 121.8 (C5), 116.5 (C3), 29.7
(–CH2–), 133.7 (i-C), 132.4 (o-C), 128.4 (m-C), 130.7
(p-C).
To the solution of C5H5NS (0.040 g, 0.17 mmol) in 15 ml
of water containing 0.3 mmol of NaOH was added a suspen-
sion of [PdCl2(dppm)] (0.098 g, 0.17 mmol) in 25 ml of
ethanol. The reaction mixture was heated for 15 min, and the
clear solution formed was left to evaporate at room temper-
ature. The product was recrystallised from chloroform and
dried in vacuo. Yield, 78%; m.p., 117–1208C. Anal. Found:
C, 59.2; H, 3.90; N, 3.80. Required for C35H30N2S2P2Pd: C,
59.0; H, 4.21; N, 3.93%. IR (KBr, cmy1): 1570s, 1430s,
1410w, 1132sh, 1120s (nC–S), 1095s (nP–C), 895m, 740s,
690s, 610w, 520s, 460w, 410w (nPd–P), 360m (nPd–S).
2.4. Elemental analyses and spectroscopic techniques
NMR (CDCl3, d ppm, J, Hz): H, 8.52d (J5, 6.6, H6), –,
C, H and N determinations were performed by the micro-
analytical laboratory of the Regional Sophisticated Instru-
mentation Centre (RSIC) of Panjab University, Chandigarh.
Infrared (IR) spectra were recorded as KBr pellets in the
range 4000–200 cmy1 on a Philips Analytical SP3-300 spec-
trophotometer. 1H NMR spectra were recorded on a Bruker
AC-200 spectrometer operating at a frequency of 200 MHz.
CDCl3 was used as a solvent with TMS (tetramethylsilane)
as the internal reference. 13C NMR spectra were recorded on
a Bruker AC-200 spectrometer operating at a frequency of
50 MHz using CDCl3 as solvent and TMS as the internal
1
6.98d (J4, 5.6, H3), –, 2.07t (–CH2–), 7.6m (Ph–P); 13C,
165.5 (C2), 147.5 (C6), 131.8 (C4), 128.4 (C5), 117.0 (C3),
29.7 (–CH2–), 133.8 (i-C), 132.5 (o-C), 128.5 (m-C),
130.8 (p-C). Complexes 8–11 were prepared similarly.
2.3.2. cis-[Pd(h1-S-C5H4NS)2(dppe] (8)
Yield, 80%; m.p., 188–1908C. Anal. Found: C, 60.0; H,
4.40; N, 4.10. Required for C36H32N2S2P2Pd: C, 59.7; H,
4.41; N, 3.86%. IR (KBr, cmy1): 1565s, 1540m, 1445s,
1415s, 1120m (nC–S), 1105s (nP–C), 1050w, 810s, 740m,
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Table 1
Summary of crystal data for compounds 1, 2 and 8
1
2
8
Empirical formula
MW
C36H32N2P2PtS2
813.79
C36H30N2P2PtS2
811.77
C36H32N2P2PdS2
725.10
T (K)
l (A)
Crystal system
293(2)
293(2)
0.71073
293(2)
0.71073
monoclinic
C2/c
37.049(10)
8.8224(17)
23.722(7)
6559(3)
90
122.227(19)
90
8
˚
0.71073
monoclinic
C2/c
37.028(7)
8.827(2)
23.698(5)
6545(2)
90
122.33(3)
90
8
1.652
4.542
triclinic
¯
Space group
P1
˚
a (A)
8.862(2)
12.462(3)
16.323(3)
1635.3(6)
92.35(3)
103.63(3)
109.68(3)
2
˚
b (A)
˚
c (A)
3
˚
V (A )
a (8)
b (8)
g (8)
Z
Dc (g cmy3
)
1.649
4.544
v–2u
1.468
0.819
v–2u
m (Mo Ka) (mmy1
Scan type
)
v–2u
2u Range (8)
h, k, l ranges
2.60–44.98
0, 39; 0, 9; y25, 21
4351
4274, 0.0372
0.721 and 0.545
3920, 388
3216
3.50–45.02
0, 9; y13, 21; y17, 17
4580
4245, 0.0440
0.97661 and 0.58438
4138, 388
800
4.06–52.40
y38, 46; 0, 10; y29, 0
6742
6570, 0.0418
0.968 and 0.937
6570, 388
2960
No. reflections collected
No. unique reflections, Rint
Maximum and minimum transmission
No. reflections with I)2s(I), parameters
F(000)
Final R indices
R1 a, wR2
0.0421, 0.0960
0.0741, 0.1401
0.978
0.0259, 0.0594
0.0324, 0.0621
1.038
0.0547, 0.0732
0.3040, 0.1056
0.906
R indices (all data), R1 b, wR2
S c on F2
Peak and hole (e A
y3
˚
)
0.706 and y0.999
0.411 and y0.524
0.653 and y1.433
a R1sSNNFoNyNFcNN/SNNFoNN.
b R1s[Sw(Fo yFc )2/Sw(Fo2)2]1/2
.
2
2
c Ss[Sw(Fo yFc )2/(nyp)]1/2, where n is total number of reflections measured, p is number of parameters.
2
2
reference. 31P NMR spectra were recorded on a Bruker ACP-
300 spectrometer operating at a frequency of 121.4 MHz with
85% phosphoric acid as the external reference (dP 32.5
ppm).
method based on F2. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were fixed geometrically
and were not refined for compounds 1 and 2, but were refined
for compound 8 using a riding model. Atomic scattering
factors were used from International Tables for Crystallog-
raphy [50]. Data reduction, structure solution, refinement
and molecular graphics were performed using SHELXTL-
PC [51–54]. A summary of the crystal data, experimental
details and refinement results are listed in Table 1.
2.5. Crystal structure determinations
The suitable light yellow prismatic crystals of compounds
1, 2 and 8 were mounted on glass fibres and used for data
collection. Cell constants and orientation matrix for data col-
lection were obtained by least-squares refinement of the dif-
fraction data from 25 reflections in the u range of 8–208 for
compounds 1 and 2 with XSCANS (Siemens Analytical X-
Ray Instruments) and 7.567-u-11.8898 for compound 8.
No detectable decompositon of the crystals occurred during
data collection. For compounds 1 and 2, data were collected
on a Siemens P4 diffractometer and for compound 8 on an
Enraf-Nonius Mach 3 automatic diffractometer [47]. The
3. Results and discussion
3.1. Synthesis and IR spectroscopy
In a recent study, it was found that reaction of N,S-bridged
dimeric Pt(C5H4NS)2 {obtained from PtCl2 with
NaqC5H4NSy} in CH3CN with PPh3 formed trans-[Pt(h1-
S-C5H4NS)2(PPh3)2] with pendant pyridyl groups in the
trans position [21]. The cis-[Pt(h1-S-C5H4NS)2(L-L)]
compounds [L-Lsdppe, dppen, etc. (1–6)] were obtained
by the reactions of PtCl4 (soluble in ethanol, unlike PtCl2)
with neutral C5H5NS in benzene in the presence of Et3N,
˚
data were collected using Mo Ka radiation (ls0.71073 A)
and v–2u scan technique, and corrected for Lorentz and
polarisation effects [48]. A semi-empirical absorption cor-
rection (psi scan) was made [49]. The structure was solved
by direct methods and refined by a full-matrix least-squares
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T.S. Lobana et al. / Polyhedron 19 (2000) 899–906
903
Fig. 1. Structure of monomeric cis-[Pt(h1-S-C5H4NS)2(dppe)] (1) showing the numbering scheme.
followed by addition of diphosphines or phosphine chalco-
genides. Palladium(II) complexes were prepared by reacting
PdCl2 (diphosphines) with C5H5NS in the presence of aque-
ous NaOH.
The IR spectra of the complexes show various character-
istic peaks of C5H4NSy, diphosphines (see Section 2). The
neutral C5H5NS shows n(N–H) at 3162 cmy1, and its
absence in the complexes shows deprotonation of the pyri-
dine-2-thione ligand (also confirmed by NMR data, see
below). The coordination to PtII/PdII via S-donor atom is
shown by the characteristic low-energy shift of n(C–S) in
the region 1110–1130 cmy1 occurring as a weak to strong
peak. The n(P_S) and n(P_Se) peaks also undergo low-
energy shifts, confirming coordination via P,S/P,Se-donor
atoms of dppmPS and dppmPSe. Other tentative assignments
due to n(M–P) and n(M–S) in the regions 400–420 cmy1
and 350–380 cmy1, respectively, have been made.
Fig. 2. Structure of monomeric cis-[Pt(h1-S-C5H4NS)2(dppen)](2)show-
ing the numbering scheme.
3.2. Crystal and molecular structures
and the geometry about Pt centres is distorted square planar
with trans P–Pt–S angles of 173.18(10), 170.31(11)8 for
compound 1 and 171.43(5), 168.97(5)8 for compound 2
(Table 2). There is a small difference in the bite angles of
both diphosphines [P(1)–Pt–P(2), 85.688 for compound 1
and 86.65(5)8 for compound 2] as well as in angles trans to
these bite angles [S(1)–Pt–S(2), 82.69(11) and 84.01(6)8
for compounds 1 and 2, respectively]. Of the cis angles about
Pt, only one is obtuse [P–Pt–S, 103.99(11)8 for compound
1 and 104.38(5)8 for compound 2]; all the others are acute
(Table 2). Significantly, an analogous complex, trans-
[Pt(h1-S-C5H4NS)2(PPh3)2] (A) containing trans pendant
pyridyl groups [21], showed trans bond angles (P–Pt–P*
and S–Pt–S*) of exactly 1808 and two acute (85.248) and
two obtuse (94.768) angles about Pt. In a relateddiphosphine
dimeric Pt complex [39], [(dppm)Pt(m2-N,S-TT)2Pt-
(dppm)] {B, dppmsPh2PCH2PPh2, H2TTs8-thiotheo-
The atomic numbering schemes of cis-[Pt(h1-S-
C5H4NS)2(dppe)] (1), cis-[Pt(h1-S-C5H4NS)2(dppen)]
(2) and cis-[Pd(h1-S-C5H4NS)2(dppe)] (8) are shown in
Figs. 1–3, respectively; the packing arrangements for com-
pounds 1 and 2 are shown in Figs. 4 and 5, respectively. The
basic monomer unit of compound 1 shows weak intermole-
˚
cular interaction (4.036 A)viaphenylgroupsoftwodifferent
Ph2P moieties (Fig. 4). However, no such interaction was
visible in compound 2 (Fig. 5), as the closest distance
between phenyl groups of two different molecules was 4.672
˚
˚
A. In compound 1, intramolecular interaction (3.663 A) is
observed between a pyridyl and a phenyl group of the same
molecule (Fig. 4).
In complexes 1 and 2, two P atoms of diphosphines and
two S atoms of C5H4NSy groups coordinate to the Pt atom
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T.S. Lobana et al. / Polyhedron 19 (2000) 899–906
Fig. 3. Structure of monomeric cis-[Pd(h1-S-C5H4NS)2(dppe)] (8) showing the numbering scheme.
Fig. 4. Molecular packing arrangement of cis-[Pt(h1-S-C5H4NS)2(dppe)]
(1).
phylline-N,S}, the diphosphine bite angle (P–Pt–P) was
73.35(12)8 and trans P–Pt–S and P–Pt–N bond angles were
168.91(11) and 171.80(3)8, respectively; other cis angles
about Pt were obtuse.
Fig. 5. Molecular packing arrangement of cis-[Pt(h1-S-C5H4NS)2(dppen)]
(2).
˚
A). In compounds 1 and 2, the bite angles of S(1)–C(15)–
The Pt–P and Pt–S distances are similar in all four cases
under discussion (Pt–P (A): for compound 1, 2.270(3),
N(1) and S(2)–C(32)–N(2) are different: compound 1,
119.8(1), 114.7(9)8; compound 2, 113.4(5), 120.1(4)8,
respectively. However, these bite angles (113–1208) are
characteristic of an S-bonded monodentate C5H4NSy moiety
[21,55]. Other characteristic bond angles, Pt–S(1)–C(15)
and Pt–S(2)–C(32), are also different in the two cases:com-
pound 1, 116.9(4), 106.1(4)8; compound 2, 109.1(2),
115.8(2)8.
Complexes 1 and 8 are isomorphous and their bond angles
and distances are similar. Considering different planes for the
complexes, the plane in compound 1 defined by the atoms
S1S2P1P2Pt makes an angle of 89.688 with the plane defined
˚
2.256(3); compound 2, 2.241(2), 2.268(1); compound A,
2.315 [21]; compound B, 2.270(3), 2.235(3) [6]. Pt–S
˚
(A): compound 1, 2.327(3), 2.389(3); compound 2,
2.370(1), 2.332(2); compound A, 2.343(2) [21]; com-
pound B, 2.356(3) [39]). There are small differences in P–
CPh and P–Calkane/alkene bond lengths in compounds 1 and 2.
The S(1)–C(15) and S(2)–C(32) bond distances are
slightly longer in compounds 1, 2 and B compared with that
in A (average: compound 1, 1.7645(11); compound 2,
1.753(6); compound A, 1.739(6); compound B, 1.751(12)
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T.S. Lobana et al. / Polyhedron 19 (2000) 899–906
905
Table 2
a pyridyl group in the vicinity ofN atomsgenerallyundergoes
a shift to the low field in the complexes relative to neutral
C5H5NS; other proton signals H(3), H(4) and H(5), all
move upfield in the complexes. This behaviour of C5H4NSy
is similar to that in trans-[Pt(h1-S-C5H4NS)2(PPh3)2][21]
and shows increased aromaticity of pyridyl groups in the
complexes [55]. The –(CH2)n–, –CH_CH– and C6H5– pro-
tons of diphosphine ligands show small low-field shifts.
The 13C NMR spectra provide more convincing informa-
tion about the uni- or bi-dentate behaviour of the C5H4NSy
moiety [15–21,56]. The C(2) carbon signal of the pyridyl
group moves upfield in the complexes (relative to free
C5H5NS) and is characteristic of an S-bonded unidentate
C5H4NSy moiety as a N,S-chelating moiety shows a low-
field shift in the C(2) signal. Further C(3) and C(6) signals
move downfield, while C(4) and C(5) signals move upfield,
the latter carbon showing more pronounced shifts [15–
21,56]. Finally, the –CH2– signals of diphosphine ligands
show significant low-field shifts. The ipso-carbon of the
C6H5– group of free ligands moves upfield in all the com-
plexes. The meta- and para-carbon signals either appear as
separate or overlap; however, the ortho-carbon signal is
almost unaffected. The –CH_CH– carbon signal of dppen
appears as a triplet at d 146.6t (JC-P, 7.5 Hz) which shifts to
a higher field at d 145.4 ppm as an unresolved singlet in
compound 2. Thus NMR shows that, in all the complexes,
pyridine-2-thiolate is coordinating to metals via an S-donor
atom with pendant pyridyl groups in cis positions.
a
˚
Selected bond lengths (A) and bond angles (8) for 1, 2 and 8
cis-[Pt(h1-S-C5H4NS)2(dppe)] (1)
Pt–P(1)
Pt–P(2)
Pt–S(1)
2.270(3)
2.256(3)
2.327(3)
2.389(3)
1.753(11)
1.774(12)
1.803(12)
1.801(12)
1.823(12)
1.823(11)
P(1)–Pt–P(2)
P(1)–Pt–S(1)
P(1)–Pt–S(2)
P(2)–Pt–S(2)
P(2)–Pt–S(1)
S(1)–Pt–S(2)
Pt–S(1)–C(15)
Pt–S(2)–C(32)
S(1)–C(15)–N(1)
S(32)–C(32)–N(2)
85.68(11)
103.99(11)
173.18(10)
87.67(11)
170.31(11)
82.69(11)
116.9(4)
106.1(14)
119.8(8)
114.7(9)
Pt–S(2)
S(1)–C(15)
S(2)–C(32)
P(1)–C(1)
P(1)–C(3)
P(2)–C(2)
P(2)–C(20)
cis-[Pt(h1-S-C5H4NS)2(dppen)] (2)
Pt–P(1)
Pt–P(2)
Pt–S(1)
2.241(2)
2.2678(14)
2.3701(14)
2.332(2)
1.761(6)
1.744(6)
1.791(5)
1.806(6)
1.822(5)
1.821(6)
P(1)–Pt–P(2)
P(1)–Pt–S(1)
P(1)–Pt–S(2)
P(2)–Pt–S(2)
P(2)–Pt–S(1)
S(1)–Pt–S(2)
Pt–S(1)–C(15)
Pt–S(2)–C(32)
S(1)–C(15)–N(1)
S(32)–C(32)–N(2)
86.65(5)
84.95(5)
168.97(5)
104.38(5)
171.43(5)
84.01(6)
109.1(2)
115.8(2)
113.4(5)
120.1(4)
Pt–S(2)
S(1)–C(15)
S(2)–C(32)
P(1)–C(1)
P(1)–C(3)
P(2)–C(2)
P(2)–C(20)
cis-[Pd(h1-S-C5H4NS)2(dppe)] (8)
Pd–P(1)
Pd–P(2)
Pd–S(1)
2.297(2)
2.263(2
P(1)–Pd–P(2)
P(1)–Pd–S(1)
P(1)–Pd–S(2)
P(2)–Pd–S(2)
P(2)–Pd–S(1)
S(1)–Pd–S(2)
Pd–S(1)–C(12)
Pd–S(2)–C(22)
S(1)–C(12)–N(1)
S(2)–C(22)–N(2)
85.19(8)
104.02(8)
171.83(8)
86.89(8)
170.78(8)
83.90(7)
116.9(3)
104.7(3)
120.4(6)
114.7(6)
2.333(2)
2.382(2)
1.744(7)
1.757(8)
1.838(6)
1.819(7)
1.839(7)
1.803(8)
Pd–S(2)
S(1)–C(12)
S(2)–C(22)
P(1)–C(1)
P(1)–C(31)
P(2)–C(2)
P(2)–C(51)
The 31P NMR spectrum of compound 2 shows two 31P
NMR signals with corresponding pairs of satellites due to
coupling from 195Pt (Is1/2), whereas compound 1 shows
one 31P signal with a pair of satellites. The presence of two
sets of 31P signals could be due to the non-equivalent pyridyl
groups facing P atoms and this non-equivalence is probably
not resolved in the dppe complex (1). While the JP-Pt con-
stants are similar in magnitude in the two cases (compound
1, 2968.2 Hz; compound 2, 2958.5, 2969.4 Hz), the coordi-
nation shifts (DdP) are different (compound 1, 58.2 ppm;
compound 2, 77.1 ppm). Thus, dppen is coordinating more
strongly to the Pt centre than dppe is. The difference is attrib-
uted to the unsaturation in the –CH_CH– moiety of dppen,
which could favour increased charge delocalisation in the
Pt–dppen moiety.
a Symmetry transformations were used to generate equivalent atoms.
by the atoms C32–36, N2, and the angle is 5.988 with the second
pyridyl group defined by atomsC15–19, N1. Thecorresponding
angles are 12.198 for compound 3 and 74.948 for complex 2.
The orientation of pyridyl groups in compound 8 is similar
to that of complex 2, the corresponding angles being 7.36 and
84.108. A further significant observation is the small angle of
13.078 between the planes defined by C32–36, N2 and C26–31
for compound 1; this explains the closest contact between a
pyridyl group and a phenyl group as described earlier. It
shows p-interactions between the two rings. In summary, the
change in alkane moiety connecting Ph2P groupsfrom–CH2–
CH2– to –CH_CH– affects the orientation of the planes of
Ph and py groups, in addition to inducing variations in bond
distances and angles as discussed above.
In conclusion, cis-[M(h1-S-C5H4NS)2(diphosphines)]-
(III) represent an interesting series of first examples with the
potential to act as precursors to develop further polymetallic
chemistry.
3.3. NMR spectroscopy
1
The observed H and 13C NMR resonances for all the
complexes are given in Section 2. Deprotonation of C5H5NS
in the complexes is evident from the absence of an NH proton
signal (dN-H, 13.4 ppm (b) for free C5H5NS) and it shows
platinum(II)–C5H4NSy bonding in complexesvia S- orN,S-
donor atoms [18–20]. The diagnostic H(6) proton signal of
Supplementary data
Supplementary data are available from the CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: q44-1223-
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T.S. Lobana et al. / Polyhedron 19 (2000) 899–906
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