Pyridine-2-thione derivatives of silver(I) and mercury(II): Crystal structures of dimeric [bis(diphenylphosphino)methane](1-oxo-pyridine-2-thionato)silver(I), [2-(benzylsulfanyl)pyridine 1-oxide]-dichloromercury(II) and phenyl(pyridine-2-thionato)mercury(II)

Article abstract of DOI:10.1039/a900405j

Silver(i) complexes, [Ag(O,S-C₅H₄NOS)(L)] [L = Ph₂PCH₂PPh₂ (dppm) 1, Ph₂P(CH₂)₄PPh₂ (dppb) 2, PPh₃ 3 or P(C₆H₄Me-m)₃ 4] were obtained from silver(I) acetate and neutral 1-hydroxypyridine-2-thione(C₅H₅NOS) in water-ethanol medium followed by addition of tertiary phosphines. Direct reaction of mercury(II) halides with 2-benzylsulfanyl)pyridine 1-oxide[C₅H₄NO(SCH₂C₆H₅)] in ethanol formed [HgX₂{C₅H₄NO(SCH₂C₆H ₅}] [X = Cl 5 or Br 6]. Similarly, organomercury(II) derivatives, Hg(R)L [R = m-O₂NC₆H₄, L = C₅H₄NS^- 7 or C₅H₄NOS^- 8; R = p-ClC₆H₄, L = C₅H₄NS^- 9 or C₅H₄NOS^- 10; R = C₆H₅, L = C₅H₄NS^- 11 or C₅H₄NOS^- 12] were prepared from Hg(R)(O₂CCH₃) and neutral pyridine-2-thiones(C₅H₅NS or C₅H₅NOS). All these have been characterised using analytical data, IR, far-IR, NMR (¹H, ¹³C or ³¹P) spectroscopy and for 1, 5 and 11 X-ray crystallography. Complex 1 exists as a dimer with dppm bridging the two Ag atoms leading to the formation of an eight membered metallacyclic ring with C₅H₄NOS^- moieties chelating to each Ag atom via O,S-donor atoms. The geometry about each Ag is highly distorted tetrahedral with bond angles varying from 72.85(7) to 137.92(4)°. Compounds 5 and 11 acquire formally dimeric structures via weaker interactions. For example, in 5, Hg binds strongly to one O, two Cl and weakly to one Cl and one S atom of a second ligand molecule. The geometry about each Hg is formally highly distorted trigonal bipyramidal with Cl(1)-Hg-Cl(2) and O(1)-Hg-S(1*) bond angles of 172.84(5) and 151.70(9)° respectively. Finally in 11 Hg is bonded strongly to one C and one S atom, relatively weakly to N{Hg-N 2.795(10), 2.879(9) A} and very weakly to a second S atom of a second ligand molecule {Hg-S 3.312(3), 3.365(3) A}. If secondary interactions are ignored the geometry about Hg is formally distorted T-shaped.

Full text of DOI:10.1039/a900405j

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Pyridine-2-thione derivatives of silver(I) and mercury(II): crystal
structures of dimeric [bis(diphenylphosphino)methane][(1-oxo-
pyridine-2-thionato)silver(I), [2-(benzylsulfanyl)pyridine 1-oxide]-
dichloromercury(II) and phenyl(pyridine-2-thionato)mercury(II)†
Tarlok S. Lobana,*a Seema Paula and Alfonso Castineirasb
a Department of Chemistry, Guru Nanak Dev University, Punjab, Amritsar-143 005, India
b Departamento de Quimica Inorganica, Universidade de Santiago, 15706-Santiago, Spain
Received 14th January 1999, Accepted 9th April 1999
Silver() complexes, [Ag(O,S-C5H4NOS)(L)] [L = Ph2PCH2PPh2 (dppm) 1, Ph2P(CH2)4PPh2 (dppb) 2, PPh3 3
or P(C6H4Me-m)3 4] were obtained from silver() acetate and neutral 1-hydroxypyridine-2-thione(C5H5NOS) in
water–ethanol medium followed by addition of tertiary phosphines. Direct reaction of mercury() halides with
2-benzylsulfanyl)pyridine 1-oxide[C5H4NO(SCH2C6H5)] in ethanol formed [HgX2{C5H4NO(SCH2C6H5}] [X = Cl
5 or Br 6]. Similarly, organomercury() derivatives, Hg(R)L [R = m-O2NC6H4, L = C5H4NSϪ 7 or C5H4NOSϪ 8;
R = p-ClC6H4, L = C5H4NSϪ 9 or C5H4NOSϪ 10; R = C6H5, L = C5H4NSϪ 11 or C5H4NOSϪ 12] were prepared from
Hg(R)(O2CCH3) and neutral pyridine-2-thiones(C5H5NS or C5H5NOS). All these have been characterised using
analytical data, IR, far-IR, NMR (1H, 13C or 31P) spectroscopy and for 1, 5 and 11 X-ray crystallography. Complex 1
exists as a dimer with dppm bridging the two Ag atoms leading to the formation of an eight membered metallacyclic
ring with C5H4NOSϪ moieties chelating to each Ag atom via O,S-donor atoms. The geometry about each Ag is highly
distorted tetrahedral with bond angles varying from 72.85(7) to 137.92(4)Њ. Compounds 5 and 11 acquire formally
dimeric structures via weaker interactions. For example, in 5, Hg binds strongly to one O, two Cl and weakly to one
Cl and one S atom of a second ligand molecule. The geometry about each Hg is formally highly distorted trigonal
bipyramidal with Cl(1)–Hg–Cl(2) and O(1)–Hg–S(1*) bond angles of 172.84(5) and 151.70(9)Њ respectively. Finally
in 11 Hg is bonded strongly to one C and one S atom, relatively weakly to N{Hg–N 2.795(10), 2.879(9) Å} and very
weakly to a second S atom of a second ligand molecule {Hg–S 3.312(3), 3.365(3) Å}. If secondary interactions are
ignored the geometry about Hg is formally distorted T-shaped.
4
The co-ordination chemistry of heterocyclic thiones is of
immense interest because such compounds mimic (a) cysteine
3
5
2
6
sulfur co-ordination in metalloenzymes, (b) electronic and
N1
S
S
N
SH
SH
structural properties of the active sites in copper “blue”
proteins involving S,N co-ordination, (c) the environment for
molybdenum in nitrogenase where S,N-chelated molybdenum
is believed to be relevant to the reduction of nitrogen by nitro-
genase, (d) interactions of nucleotides and nucleic acid and
bases with metals,1,2 etc. In addition, the use of sulfur-co-
ordinated gold() complexes in the treatment of rheumatoid
arthritis, platinum complexes in anticancer activity and a var-
iety of biochemical applications have stimulated interest in
heterocyclic thiones and their derivatives.3–6 Using the simplest
molecules, pyridine-2-thione (I, C5H5NS) and its N-oxide
derivative, namely 1-hydroxypyridine-2-thione (II, C5H5NOS),
several investigations have been made by others4–6 and our
laboratory.7–16 Compound I and its anion C5H4NSϪ bind in
several ways4–6 while C5H5NOS co-ordinates only in its anionic
form via its O,S-donor atoms in a chelating mode.7
Silver() is known to form mono-, di-, hexa- and octa-nuclear
complexes with neutral C5H5NS or its derivatives containing
substituents in the pyridyl ring.17–20 Similarly, there are a few
reports on the use of organic substituents on sulfur which
can significantly modulate the co-ordination properties of
C5H5NOS.21 Further, the co-ordination chemistry of organo-
mercury() cations, RHgϩ (R = CH3, Ph, etc.) is important in
view of their toxicity to living systems by binding to cysteine
thiolate groups and thus there is need for detoxification of
mercury similar to metallothioneins.22 There are limited
H
Ia
Ib
N
N
OH
O
IIa
IIb
CH2
N
O
S
III
reports on the interaction of heterocyclic thiones with organo-
mercury() substrates.3–6,23
In this paper we report (a) complexes of silver() containing
2-thioxopyridine-1-one and tertiary phosphines as co-ligands,
(b) 2-(benzylsulfanyl)pyridine 1-oxide III complexes with mer-
cury() halides and (c) arylmercury() derivatives containing
m-C6H4, p-ClC6H4 and Ph as organic moieties and C5H4NSϪ,
C5H4NOSϪ anions.24
Experimental
General materials
Mercury() chloride, bromide (used after recrystallisation from
ethyl alcohol), silver acetate, silver carbonate and triphenyl-
† The chemistry of pyridinethiols and related ligands. Part 10.24a
J. Chem. Soc., Dalton Trans., 1999, 1819–1824
1819

View Article Online
phosphine were from M/s Sisco Laboratories, Bombay, tri-m-
tolylphosphine and Ph2PCH2PPh2 from Pressure Chemicals
Co. Ltd., Pittsburg, USA; other materials were prepared as
reported.8,9 The compound C5H5NS was prepared by heating
2-hydroxypyridine with P2S5, C5H5NOS by oxidation of 2-
chloropyridine using H2O2 followed by reaction with a mixture
of NaSH (prepared by passing H2S gas through NaOEt in
EtOH)7–9 and Na2S. Sodium salts, NaϩC5H4NSϪ and NaϩC5H4-
NOSϪ, were prepared by treating neutral C5H5NS and
C5H5NOS with NaOEt prepared in situ.7 C5H4NO(SCH2C6H5)
was prepared by treating the sodium salt of C5H5NOS with
benzyl chloride in 1:1 mole ratio (mp 158–59 ЊC).24a Phenyl-
mercury() chloride (Fluka chemika, Switzerland) was used
after recrystallisation from ethanol; m-nitrophenyl- and p-
chlorophenyl-mercury() chlorides were prepared by literature
methods.25–27
[HgCl2{C5H4NO(SCH2C6H5)}] 5. This was prepared by
direct reaction of mercury() chloride (0.100 g, 0.37 mmol)
with 2-(benzylsulfanyl)pyridine 1-oxide (0.080 g, 0.37 mmol) in
ethanol at room temperature under magnetic stirring (48 h) and
slow evaporation gave fine crystals of the complex. Yield 50%,
mp 190–192 ЊC (decomp) (Found: C, 29.9; H, 2.41; N, 2.89.
Required for C12H11Cl2HgNOS: C, 29.5; H, 2.25; N, 2.86%). IR
(cmϪ1): 1250m, 1220s, ν(C᎐S); 1090m, ν(N–O); 837s, δ(N–O);
᎐
1
710s, 700s, 333s, ν(Hg–O); 307m, 288m, ν(Hg–Cl). NMR: H,
δ 8.40 [d, J(H5H6) 6.8, H6], 7.55 (broad, H4), 7.38 (broad, H3)
and 7.23 [td, J(H5H4,6) 6.8, J(H3H5) 2.2 Hz, H5]; 13C, δ 154.5(C2),
140.8(C6), 129.0(C4), 125.4(C5) and 123.1(C3); benzyl group,
37.1(CH2), 136.9(i-C), 130.0–132.2(o-, m- and p-C).
[HgBr2{C5H4NO(SCH2C6H5)] 6. This was prepared by the
same method. Yield 60%, mp 180–185 ЊC (Found: C, 25.7; N,
2.40. Required for C12H11Br2HgNOS: C, 25.4; N, 2.37%). IR
(cmϪ1): 1240m, 1220s, ν(C᎐S); 1090m, ν(N–O); 830s, δ(N–O);
Preparations
᎐
1
710s, 690s, ν(C–S). NMR: H, δ 8.19 (broad, H6), 7.10–7.47
[Ag(C5H4NOS)(dppm)] 1. To a solution of silver() acetate
(0.100 g, 0.6 mmol) in distilled water (20 ml) was added an
ethanolic solution of C5H5NOS (0.076 g, 0.6 mmol) dropwise
under magnetic stirring. After 0.5 h was added an ethanolic
solution of dppm (0.230 g, 0.6 mmol) dropwise and stirred
overnight. The white precipitates formed were filtered off,
washed with water and dried in vacuo. Crystals were grown
from ethanol–benzene–dichloromethane by slow evaporation
at room temperature. Yield 60%, mp, 120–123 ЊC (Found: C,
57.3; N, 2.31. Required for C30H26AgNOP2S: C, 58.0; N,
(broad, H3,4,5); 13C, δ 143.0(C6), 125.5(C4), 121.7(C5), 120.5(C3);
benzyl group, 36.8(CH2), 128.4(o-C), 127.3(m-C) and 128.4
(p-C).
[Hg(m-O2NC6H4)(C5H4NS)] 7. To a water–acetone solution
of [Hg(m-O2NC6H4)(O2CCH3)] (25 ml) [prepared by treating
Hg(m-O2NC6H4)Cl (0.100 g, 0.28 mmol) with Ag(O2CCH3)
(0.046 g, 0.28 mmol)] was added C5H5NS slowly (0.030 g, 0.27
mmol) in ethanol (20 ml). The contents were stirred for 5 h
when a white fibrous crystalline product separated. It was
filtered off washed with EtOH and then dried in vacuo. Yield
55% mp 140 ЊC (decomp.) (Found: C, 30.0; H, 1.33; N, 6.41.
Required for C11H8HgN2O2S: C, 30.5; H, 1.85; N, 6.47%). IR
2.34%). IR (cmϪ1): 1215m, 1190m, ν(C᎐S); 1100m, ν(P–C);
᎐
1080m, ν(N–O); 830m, δ(N–O). NMR (see structure Ia for
1
numbering scheme): H, δ 8.18 [d, J(H5H6) 6.4, H6], 6.84 [td,
J(H4H3,5) 7.6, J(H4H6) 1.4, H4], 7.57 [d, J(H3H4) 8.4, H3] and
6.65 [td, J(H5H4,6) 6.8, J(H3H5) 1.9 Hz, H5]; 13C, δ 162.7(C2),
140.7(C6), 133.5(C4), 127.2(C5), 118.8(C3); phosphine signals,
29.8(CH2), 135.9(i-C), 135.0(o-C), 130.6(m-C), 131.9(p-C). 31P,
δ 15.43, ∆δ = 36.7. Complexes 2–4 were prepared by the same
method.
(cmϪ1): 1124m, ν(C᎐S); 478s, ν(Hg–C); 389s, ν(Hg–S). NMR:
᎐
1H, δ 8.13 [d, J(H5H6) 4.1, H6], 7.40 [td, J(H4H3,5) 7.3, J(H4H6)
1.8, H4], 8.08 [d, J(H3H4) 7.1, H3] and 6.9 [td, J(H5H4,6) 6.2,
J(H3H5) 1.6 Hz, H5]; 13C, 168.6(C2), 146.7(C6), 136.1(C4),
122.3(C5) and 118.5(C3); 1H, (m-O2NC6H4)Hg, 8.29 [d, J(H2H4)
2.1 Hz], 7.21 [d, J(H5H6) 8.2, H6], 7.55 [t, J(H5H4,6) 7.8, H5] and
7.71 [d, J(H4H5) 7.3 Hz, H4]; 13C, δ 128.3(C2,C6), 141.7(C3),
122.3(C5) and 130.0(C4). Other complexes 8–12 were prepared
similarly (see structures IV and V for numbering scheme of
RHgϩ moiety).
[Ag(C5H4NOS){Ph2P(CH2)4PPh2}] 2. Yield 55%, mp 193–
195 ЊC (Found: C, 57.6; H, 4.91; N, 2.34. Required for
C33H32AgNOP2S: C, 57.4; H, 4.64; N, 2.03%). IR (cmϪ1):
1210m, 1190m, ν(C–S); 1100m, ν(P–C); 1080m, ν(N–O); 833m
1
δ(N–O). NMR: H, δ 8.12 [dd, J(H5H6) 6.6, J(H4H6) 1.4, H6],
6.85 [td, J(H4H3,5) 7.7, J(H4H6) 1.2, H4], 7.67 [dd, J(H3H4) 8.3,
J(H3H5) 1.9, H3] and 6.62 [td, J(H5H4,6) 6.9, J(H3H5) 1.9 Hz,
H5]; 13C, δ 160.0(C2), 137.8(C6), 130.8(C4), 124.8(C5), 116.0(C3);
phosphine signals, 27.0–29.1(CH2), 133.2(i-C), 132.0(o-C, JCP
16.6) 129.2 (m-C, JCP 8.5 Hz) and 128.9(p-C); 31P, δ Ϫ1.95,
∆δ = 19.0.
Cl
4
NO2
3
1
1
Hg
Hg
IV
V
[Ag(C5H4NOS)(PPh3)] 3. Yield 60%, mp, 170 ЊC (Found: C,
[Hg(m-O2NC6H4)(C5H4NOS)] 8. Yield 70%, mp 249–250 ЊC
54.6; H, 3.72; N, 2.17. Required for C23H19AgNOPS: C, 55.6;
H, 3.83; N, 2.82%). IR (cmϪ1): 1215s, 1190s, ν(C᎐S); 1105s, ν(P–
(Found: C, 29.4; H, 1.36; N, 6.12. Required for C11H8HgN2O3S:
᎐
C, 29.4; H, 1.78; N, 6.23%). IR (cmϪ1): 1209m, ν(C᎐S); 1089m,
1
᎐
C); 1080s, δ(N–O); 833m, ν(N–O); 338m, ν(Ag–O). NMR: H,
δ 8.29 [d, J(H5H6) 6.6, H6], 6.99 [t, J(H4H3,5) 7.3, H4], 7.78 [dd,
J(H3H4) 8.3, J(H3H5) 1.9, H3] and 6.78 [td, J(H5H4,6) 6.9,
J(H3H5) 1.9 Hz, H5]; 13C, δ 164.9(C2), 137.6(C6), 130.7(C4),
124.9(C5), 116.5(C3); phosphine signals, 130.1(i-C), 133.1(o-C,
JCP 16.5), 128.0(m-C, JCP 10.4 Hz) and 129.6(p-C);24 31P,
δ 12.57, ∆δ = 19.7.
ν(N–O); 833m, δ(N–O); 435s, ν(Hg–C); 423s, ν(Hg–O); 336s,
ν(Hg–S). NMR: 1H, δ 8.48 [d, J(H5H6) 5.7, H6], 7.34 [td,
J(H4H3,5) 7.8, J(H4H6) 1.3, H4], 8.02 [ddd, J(H3H4) 8.5, J(H3H5)
2.5, J(H3H6), 1.1, H3] and 7.15 [td, J(H5H4,6) 6.9, J(H3H5) 1.6
Hz, H5]; (m-O2NC6H4)Hg, 8.41 [d, J(H2H4) 2.4, H2], 7.82 [dd,
J(H5H6) 8.2, J(H4H6) 1.7, H6], 7.65 [t, J(H5H4,6) 7.8, H5] and
7.94 [d, J(H4H5) 7.3 Hz, H4].
[Ag(C5H4NOS){P(C6H4Me-m)3}] 4. Yield 55%, mp 220–
225 ЊC (decomp.) (Found: C, 59.0; H, 4.88; N, 2.10. Required
for C26H28AgNOPS: C, 58.0; H, 4.64; N, 2.60%). IR (cmϪ1):
[Hg(p-ClC6H4)(C5H4NS)] 9. Yield 60%, mp 123–126 ЊC
(Found: C, 32.1; H, 1.69; N, 3.23. Required for C11H8ClHgNS:
1209m, 1189m, ν(C᎐S); 1096s, ν(P–C); 1080s, ν(N–O); 831m,
C, 31.2; H, 1.89; N, 3.31%). IR (cmϪ1): 1124s, ν(C᎐S); 485s,
᎐
᎐
δ(N–O); 321m, ν(Ag–O). NMR: 1H, δ 8.11 [d, J(H5H6) 6.6, H6],
6.81 [t, J(H4H3,5) 7.6, H4], 7.60 [d, J(H3H4) 7.2, H3] and 6.58 [t,
J(H5H4,6) 6.4 Hz, H5]; 13C, δ 160.9(C2), 131.8 (C4), 125.8(C5),
117.1(C3); phosphine signals, 21.5(CH3), 131.8(i-C), 131.0(o-C1,
JCP 14.4), 134.8(o-C2, JCP 20.1), 138.8(m-C1), 128.8(m-C2, JCP
10.1 Hz) and 131.5(p-C); 31P, δ 4.17, ∆δ = 13.4.
479s, ν(Hg–C); 389m, ν(Hg–S). NMR: H, δ 8.09 [d, J(H5H6)
1
4.6, H6] and 6.91 [td, J(H5H4,6) 6.2, J(H3H5) 1.0 Hz, H5]; 13C,
δ 163.5(C2), 146.7(C6), 135.9(C4), 124.1(C5) and 118.8(C3); H,
1
(p-ClC6H4)Hg, δ 7.17 [d, J(H2,6H3,5) 8.9 Hz, H2, H6] and 7.29–
7.35(H3,H5); 13C, δ 133.5(C1), 127.9(C2,C6), 136.4(C3,C5) and
137.4(C4).
1820
J. Chem. Soc., Dalton Trans., 1999, 1819–1824

View Article Online
[Hg(p-ClC6H4)(C5H4NOS)] 10. Yield 60%, mp 195–197 ЊC
collected at 293 K using Mo-Kα radiation (λ = 0.71073 Å) and
(Found: C, 31.1; H, 2.06; N, 3.06. Required for C11H8ClHg-
the ω scan technique and corrected for Lorentz-polarisation
effects.29 A semiempirical absorption correction (ψ scan) was
made.30 A summary of the crystal data, experimental details
and refinement results is given in Table 1.
NOS: C, 31.1; H, 1.83; N, 3.20%). IR (cmϪ1): 1208s, ν(C᎐S);
᎐
1088s, ν(N–O); 833m, δ(N–O); 480s, ν(Hg–C); 373m, ν(Hg–O);
354m, ν(Hg–S). NMR: 1H, δ 8.26 [dd, J(H5H6) 6.6, J(H4H6) 1.0,
H6], 7.14 [td, J(H4H3,5) 7.8, J(H4H6) 1.4, H4], 7.65 [dd, J(H3H4)
8.3, J(H3H5) 1.8, H3] and 6.89 [td, J(H5H4,6) 7.0, J(H3H5) 1.8
Hz, H5]; 13C, δ 152.7(C2), 139.3(C6), 129.8(C4), 122.4(C5) and
Structure solution and refinement. The structures were solved
by direct methods31 which revealed the positions of all non-
hydrogen atoms and refined on F2 by a full matrix least squares
procedure using anisotropic displacement parameters.32 The
hydrogen atoms were located from difference maps and refined
isotropically. Atomic scattering factors were taken from ref. 33,
while molecular graphics were drawn with ZORTEP.34
CCDC reference number 186/1422.
1
118.8(C3); H, (p-ClC6H4)Hg, δ 7.29 [d, J(H2,6H3,5) 7.6, H2H6)
and 7.35 [d, J(H2,6H3,5), 7.6 Hz, H3,H5]; 13C, δ 133.3(C1),
127.7(C2,C6), 137.1(C3,C5) and 139.4 (C4).
[Hg(C6H5)(C5H4NS)] 11. Yield 70%, mp 120–122 ЊC (Found:
C, 33.5; H, 2.06; N, 3.72. Required for C11H9HgNS; C, 34.0; H,
2.32; N, 3.61%). IR (cmϪ1): 1124s, ν(C᎐S). NMR: 1H, δ 8.18 [dd,
᎐
See http://www.rsc.org/suppdata/dt/1999/1819/ for crystallo-
graphic files in .cif format.
J(H5H6) 5.0, J(H4H6) 0.9, H6] and 6.98 [td, J(H5H4,6) 6.2,
J(H3H5) 0.9, H5]; (C6H5)Hg, δ 7.41–7.46 (H2,H6,H4) and 7.25–
7.33 (H3,H5); 13C, δ 164.7(C2), 147.7(C6), 136.5(C4), 125.1(C5)
and 119.2(C3).
Results and discussion
General comments
[Hg(C6H5)(C5H4NOS)] 12. Yield 65%, mp 130–135 ЊC
Stoichiometric reactions of Ag(O2CCH3) with C5H5NOS in
the presence of tertiary phosphines formed Ag(C5H4NOS)L
products [L = Ph2P(CH2)mPPh2, m = 1 or 4, PPh3 or P(C6H4Me-
m)3]. The complexes were generally soluble in organic solvents,
though organomercury derivatives have relatively low solubility
in C6H6, EtOH and MeOH. Direct reactions of HgX2 (X = Cl
or Br) with C5H4NO(SCH2C6H5) in EtOH formed products of
stoichiometry [HgX2{C5H4NO(SCH2C6H5}] (X = Cl or Br).
However, there was no reaction with HgI2 and products with
CuX (X = Cl, Br or I) were air sensitive and adducts could not
be isolated. Reaction of HgRCl with NaC5H4NS (or NaC5H4-
NOS) in EtOH {or of Hg(R)(O2CCH3) with neutral ligands}
formed Hg(R)L products [R = m-O2NC6H4, p-ClC6H4 or C6H5;
L = C5H4NSϪ or C5H4NOSϪ]. Reactions of Hg(R)L with
tertiary phosphines were complex and no product could be
established. This is in line with the chemistry of the RHgϩ
moiety which prefers two- or three-co-ordinated complexes
and extension of the co-ordination number to 4 or higher is not
common.35
(Found: C, 32.1; H, 2.15; N, 3.37. Required for C11H9HgNOS:
C, 32.7; H, 2.23; N, 3.46%). IR (cmϪ1): 1214s, ν(C᎐S); 1088m,
᎐
ν(N–O); 834m, δ(N–O); 451s, ν(Hg–C); 377m, ν(Hg–O); and
330m, ν(Hg–S). NMR: 1H, δ 8.26 [dd, J(H5H6) 6.6, J(H4H6) 1.0,
H6], 7.11 [td, J(H4H3,5) 7.8, J(H4H6) 1.0, H4], 7.64 [dd, J(H3H4)
8.3, J(H3H5) 1.5, H3] and 6.87 [td, J(H5H4,6) 6.9, J(H3H5) 1.7
Hz, H5]; 13C, δ 151.9(C2), 139.3(C6), 127.6(C4), 126.0(C5) and
118.7(C3); 1H, (C6H5)Hg, δ 7.37 [dd, J(H3H2,6) 8.0, J(H4H2,6) 1.4,
H2, H6], 7.30[t, J(H2H4), J(H6H2,4) 7.0, H2(or H6), H4] and
7.19 [t, J(H4H3,5) 7.3 Hz, H4]; 13C, 129.8(C1), 136.2(C2,6) and
127.8(C3–5).
NMR of ligands
1
C6H5NS: H, δ 7.56 [ddd, J(H5H6) 6.3, J(H4H6) 1.6, J(H3H6)
0.8, H6], 7.34 [ddd, J(H3H4) 8.7, J(H4H5) 7.0, J(H4H6) 1.8, H4],
7.49 [dt, J(H3H4) 8.7, J(H3H5,6) 0.8, H3] and 6.73 [td, JH5H4,6)
6.7, J(H3H5) 1.2 Hz, H5]; 13C, δ 175.6(C2), 137.0(C6), 135.9(C4),
132.8(C5) and 113.1(C3). C5H5NOS: 1H, δ 8.02 [dd, J(H5H6) 6.7,
J(H4H6) 1.2, H6], 7.21 [td, J(H4H3,5) 7.9, J(H4H6) 1.4, H4], 7.60
[dd, J(H3H4) 8.6, J(H3H5) 1.5, H3] and 6.72 [td, J(H5H4,6) 7.0,
J(H3H5) 1.6 Hz, H5]; 13C, 166.0(C2), 131.6(C6), 130.3(C4),
Crystal and molecular structures
1
131.2(C5) and 113.1(C3). C5H4NO(SCH2C6H5): H, δ 8.18 [d,
The atomic numbering schemes of [Ag(C5H4NOS)(dppm)], 1,
[HgCl2{C5H4NO(SCH2C6H5)}] 5 and [Hg(C6H5)(C5H4NS)] 11
are shown in Figs. 1–3 respectively; bond lengths/angles are
listed in Table 2. Complex 1 exists as a centrosymmetric dimer
with no interaction between the dimers. The two dppm
molecules bridge two Ag(C5H4NOS) moieties forming a eight
membered Ag2P4C2 metallacyclic ring with C5H4NOS chelated
to each Ag. Each Ag atom acquires distorted tetrahedral geom-
etry by co-ordinating to one O, one S and two P atoms. The
angles about each Ag atom vary from 72.85(7) to 137.92(4)Њ
with the bite angle of C5H4NOSϪ, O(1)–Ag–S(1) being the
shortest and P(1)–Ag–P(2) the largest (Table 2). Two Ag–P dis-
tances are different [2.4254(10), 2.4914(11) Å], while two Ag–S
and two Ag–O distances are equal [Ag–S 2.5844(12), Ag–O
2.440(3) Å].20 This is unlike those in 3 where the Ag–P and
Ag–O distances are equal [Ag–P 2.3824(10), Ag–O 2.343(3) Å]
while the Ag–S distances are significantly different [Ag–S
2.5072(10), 2.8218(11) Å] obviously due to sulfur bridging the
two Ag atoms, VI. There is no Ag ؒ ؒ ؒ Ag interaction [3.8457(7)
Å]37 unlike that observed in 3 [Ag ؒ ؒ ؒ Ag 3.2472(11) Å].24 This
weak interaction is similar to the CuI ؒ ؒ ؒ CuI interaction in the
sulfur bridged dinuclear complex [{CuI(C5H5NS)[P(C6H4Me-
p)3]}2].15 The S(1)–C(1)py, N(1)–O(1) and N(1)–C(1) distances
suggest double bond character and thus charge density is
delocalised in the S–C–N–O moiety.4–6,24,37
J(H5H6) 6.4, H6], 7.09 (broad), 7.37 (broad) and 6.98 [td,
J(H4H5) 6.5, J(H3H5) 2.6 Hz, H5]; 13C, δ 137.8(C2), 133.8(C6),
124.6(C4), 121.0(C5) and 119.6(C3).
Physical measurements
The elemental analyses for C,H and N were obtained with a
Carlo-Erba 1108 microanalyser (Santiago, Spain) or from
RSIC Chandigarh. The melting points were determined with a
Gallenkamp electrically heated apparatus. The infrared spectra
were recorded in KBr pellets (4000–400 cmϪ1) or Nujol mulls
in polyethene sheets (500–100 cmϪ1) on a Bruker 1FS 66V
spectrometer. The NMR spectra were recorded in CDCl3 using
(i) a Bruker AMX 300.13 spectrometer and 75.48 MHz probe
frequencies (1H and 13C respectively) with TMS as the internal
reference and (ii) a Bruker AMX 500 spectrometer at 202.45
MHz probe frequency (13P-{1H} with 85% H3PO4 as the
external reference (δ 27.5).
X-Ray data collection and reduction
Suitable colourless prismatic crystals of complexes 1, 5 and 11
were mounted on glass fibers and used for data collection. Cell
constants and an orientation matrix for data collection were
obtained by least squares refinement of the diffraction data
from 25 reflections in the ranges (a) 11.491 < θ < 42.234Њ for
1, (b) 9.372 < θ < 18.159Њ for 5 and 9.319 < θ < 20.811Њ in an
Enraf-Nonius MACH3 automatic diffractometer.28 Data were
In compound 5 Hg forms normal bonds to two Cl and one O
atom; however, an S atom binds to a second HgCl2{C5H4NO-
(SCH2C6H5)} unit leading to the formation of the dimer
J. Chem. Soc., Dalton Trans., 1999, 1819–1824
1821

View Article Online
Fig. 1 Perspective view of [{Ag(C5H4NOS)(dppm)}2] 1 with the num-
bering scheme. The thermal ellipsoids are drawn at the 30% probability
level.
Fig. 2 Perspective view of [HgCl2{C5H4NO(SCH2C6H5}] 5. Details as
in Fig. 1.
O
L
S
S
L
Ag
Ag
O
VI
[{HgCl2[C5H4NO(SCH2C6H5)]}2] (Fig. 2). This Hg ؒ ؒ ؒ S(1*)
interaction is weak [3.3116(14) Å] and close to the sum of the
van der Waals radii.37 Similarly, the Hg ؒ ؒ ؒ Cl(1*) distance
3.2317(14) Å is slightly longer than sum of the van der Waals
radii [3.30 Å]. In the dimer the geometry about each Hg can be
described as distorted trigonal bipyramidal with Cl(1)–Hg–
Cl(2) (equatorial) and O(1)–Hg–S(1*) (axial) bond angles of
172.84(5) and 151.70(9)Њ respectively. There is
a weak
Fig. 3 Perspective view of [Hg(C6H5)(C5H4NS)] 11. Details as in
O(1) ؒ ؒ ؒ S(1) interaction [2.679(4) Å] less than the sum of the
van der Waals radii [3.30 Å], but more than a normal single
bond [O–S 1.75 Å].36,37 The S(1)–C(6) distance [1.831(7) Å] is
somewhat longer than a single bond [1.81 Å] and lengthening
of this bond as well as some other bonds of the CH2C6H5
moiety could be due to the combined effect of Hg–O co-
ordination and O ؒ ؒ ؒ S interaction (Table 2). The phenyl group
makes an angle of 79.24Њ with the plane of the pyridyl group.
Similarly the pyridyl group makes an angle of 50.01Њ with the
plane defined by Cl(1)HgCl(2)O(1).
In compound 11 the mercury atom is bonded strongly to one
C{Hg(1)–C(11) 2.062(9) Å} and one S atom {Hg(1)–S(1)
2.376(3) Å] (Fig. 3, Table 2). The N(1) atom of one pyridyl
moiety is at a distance of 2.795(10) Å from the Hg atom and it
shows weak interaction {sum of van der Waals radii, 3.05 Å}.
However, this Hg ؒ ؒ ؒ N(1) interaction is stronger than that in
HgCH3(C5H4NS) {Hg ؒ ؒ ؒ N 2.980(5) Å}.23 Further, the
Hg(1)–S(2) distance of 3.365(3) Å is close to the van der
Waals distance (3.30 Å) and thus 11 forms a weak centro-
symmetric dimer, [{Hg(C6H5)(C5H4NS)}2]. The angle (C11)–
Hg(1)–S(1) [175.2(3)Њ] deviates from linearity and the S(1)–
Hg(1)–N(1) angle is 60.57(18)Њ. This shows that the geometry
about each Hg can be treated as distorted T-shaped. The
plane defined by atoms Hg, C(11)–C(16) makes an angle of
89.65 with that defined by S(1), C(17)–C(19), C(40), C(111),
N(1), Hg(1).
Fig. 1.
Spectroscopy
The infrared and NMR spectral data are listed in the Experi-
mental section. The IR spectrum of complex 1 showed diag-
nostic ν(C᎐S) peaks at 1215m, 1190m, ν(N–O) at 1080m and
᎐
δ(N–O) at 830m cmϪ1 [cf. C H NOS, 1225s, ν(C᎐S); 1082,
᎐
5
5
ν(N–O); 832m, δ(N–O)] supporting the O,S binding of the
C5H4NOS moiety in its characteristic modes.7 A similar situ-
ation pertains for the complexes 2–4, 8, 10 and 12. The ν(M–S),
ν(M–O) or ν(Hg–Cl) bands could be located for 3, 5, 6, 8, 10
and 12. For the C5H4NSϪ complexes 7, 9 and 11 the ν(C᎐S)
᎐
peak shows a low energy shift of 15 cmϪ1 [cf. C H NS, ν(C᎐S)
᎐
5
5
7–16
1139s cmϪ1
]
supporting Hg–S interaction. The weak
Hg ؒ ؒ ؒ N interaction revealed from the crystal data could not be
identified from IR data. The spectra of 5 and 6 show mainly
intensity changes in the characteristic regions for C–S single
(710–690 cmϪ1) and C᎐S double or partially double bonds
᎐
(1250–1180 cmϪ1).7–16
1H and 13C NMR spectra (see structure Ia for numbering
scheme). From the proton NMR of complexes 7, 9 and 11, the
absence of a NH signal shows that anionic C5H4NSϪ is bonded
to Hg. The diagnostic H(6) and H(5) signals of the pyridyl
moiety provide information about the co-ordination of the
1822
J. Chem. Soc., Dalton Trans., 1999, 1819–1824

View Article Online
Table 1 Summary of crystal data for compounds 1, 5 and 11
1
5
11
Chemical formula
M
K
C30H26AgNOP2S
618.39
293(2)
C12H11Cl2HgNOS
488.77
293(2)
C11H9HgNS
387.84
293(2)
Crystal system
Space group
Triclinic
P1
Triclinic
P1
Monoclinic
C2/c
¯
¯
a/Å
b/Å
11.2139(4)
12.2698(9)
12.6138(11)
1355.86(16)
60.275(6)
67.096(4)
88.802(5)
2
7.983
5823
5526
0.0251
6.4265(5)
11.1825(11)
11.7128(9)
713.70(10)
112.297(6)
99.680(6)
105.797(6)
2
11.289
3149
2880
0.0179
30.135(3)
6.7304(11)
23.061(3)
4355.7(10)
c/Å
U/Å3
α/Њ
β/Њ
γ/Њ
Z
111.371(9)
16
14.283
5367
5234
µ(Mo-Kα)/mmϪ1
No. reflections collected
No. unique reflections
Rint
0.0733
Final R1, wR2 [I >2σ(I )]
(all data)
0.0396, 0.1008
0.0657, 0.1116
0.0259, 0.0596
0.0469, 0.0650
0.0427, 0.0728
0.1953, 0.0971
the 13C NMR signals of 7, 9 and 11 support neither essentially
S-bonded nor N,S-chelating or bridging C5H4NSϪ when com-
pared with literature trends because the C(6) carbon remains
significantly low field. This points to an intermediate situation
where weak Hg ؒ ؒ ؒ N interaction is suggested in addition to
normal Hg–S bonding.8,15,16,23,38,39 The spectral trends of
C5H4NOSϪ compounds of mercury (8, 10, 12) and silver (1–4)
are suggestive of O,S chelation as these show characteristic
upfield shifts for C(2) and C(4) carbons,40 while other carbons
show trends similar to that of C5H4NSϪ. In the case of the silver
compounds, tertiary phosphines do shift the C(2) signals to low
field as compared to those of the mercury compounds. For
compounds 5 and 6 all the pyridyl protons except H(3) and
carbons undergo low-field shifts.
Table 2 Selected bond lengths (Å) and angles (Њ)
[{Ag(C5H4NOS)(dppm)}2] 1
Ag–P(2)
Ag–P(1)
Ag–O(1)
Ag–S(1)
2.4254(10)
2.4914(11)
2.440(3)
N(1)–C(5)
N(1)–C(1)
Ag ؒ ؒ ؒ Ag*
S(1)–C(1)
1.369(6)
1.370(5)
3.8457(7)
1.721(5)
2.5844(12)
P(2)–Ag–P(1)
P(2)–Ag–O(1)
P(2)–Ag–S(1)
P(1)–Ag–O(1)
P(1)–Ag–S(1)
137.92(4)
107.22(8)
124.55(4)
96.58(8)
95.16(4)
Ag–O(1)–N(1)
Ag–S(1)–C(1)
S(1)–C(1)–N(1)
O(1)–Ag–S(1)
117.6(2)
101.52(15)
121.1(3)
72.85(7)
[HgCl2(C12H11NOS)] 5
Hg–Cl(2)
Hg–Cl(1)
Hg–O(1)
Cl(1) ؒ ؒ ؒ Cl(1*)
Hg ؒ ؒ ؒ S(1*)
2.289(2)
2.316(1)
2.568(4)
4.081(3)
3.312(1)
S(1)–C(5)
S(1) ؒ ؒ ؒ C(6)
S(1)–O(1)
Hg ؒ ؒ ؒ Hg*
Hg ؒ ؒ ؒ Cl(1*)
1.750(5)
1.831(7)
2.679(4)
3.869(5)
3.232(1)
The 31P NMR spectra of the silver() complexes show single
peaks at positions different from the ligand peaks. The lack of
coupling from 107Ag/109Ag [107Ag, abundance 51.35%, I = 1/2;
109Ag, abundance, 48.65%, I = 1/2} suggests fast equilibrium
between co-ordinated and dissociated phosphines. The co-
ordination shifts (∆δP = δcomplex Ϫ δligand) for 1, 2, 3 and 4 are
36.7, 19.0, 19.7 and 13.4 ppm respectively which shows that the
binding of phosphine ligands to the Ag(C5H4NOS) moiety
varies in the sequence: dppm > PPh3 ≈ dppb > P(C6H4Me-p)3.
The binding of tertiary phosphines to CuI in analogous dimeric
[{CuX(C5H5NS)L}2] complexes [L = P(C6H4Me-m)3 or P(C6-
H4Me-p)3; X = Cl, Br or I] was also labile.15
Cl(2)–Hg–Cl(1)
Cl(2)–Hg–O(1)
Cl(1)–Hg–O(1)
C(5)–S(1)–C(6)
C(5)–S(1)–O(1)
172.84(5)
98.43(11)
87.12(1)
101.6(3)
58.3(2)
Hg–O(1)–S(1)
C(6)–S(1)–O(1)
N(1)–O(1)–Hg
N(1)–O(1)–S(1)
117.6(2)
159.3(2)
120.3(3)
71.8(3)
[Hg(C6H5)(C5H4NS)] 11
Hg(1)–C(11)
Hg(1)–S(1)
Hg(1) ؒ ؒ ؒ N(1)
Hg(2) ؒ ؒ ؒ N(2)
2.062(9)
Hg(1) ؒ ؒ ؒ S(2)
S(1) ؒ ؒ ؒ Hg(2)
Hg(2)–C(21)
Hg(2)–S(2)
3.365(3)
3.312(3)
2.054(9)
2.380(3)
2.376(3)
2.795(10)
2.879(9)
Acknowledgements
One of us (S. P.) is grateful to the Guru Nanak Dev University
for a research fellowship. We thank Professor J. S. Casas,
University of Santiago, Spain for instrumental facilities, and to
the referees for useful comments.
C(11)–Hg(1)–S(2)
S(1)–Hg(1)–S(2)
N(1)–Hg(1)–S(2)
C(21)–Hg(2)–S(1)
Hg(1)–S(1)–Hg(2)
C(21)–Hg(2)–S(2)
C(21)–Hg(2)–N(2)
95.3(3)
85.23(9)
89.4(2)
96.1(3)
93.6(2)
177.3(3)
119.6(3)
C(11)–Hg(1)–S(1)
C(11)–Hg(1)–N(1)
S(1)–Hg(1)–N(1)
S(2)–Hg(2)–N(2)
S(2)–Hg(2)–S(1)
N(2)–Hg(2)–S(1)
Hg(2)–S(2)–Hg(1)
175.2(3)
124.2(3)
60.57(18)
59.97(19)
86.38(9)
78.38(17)
92.34(9)
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