Syntheses and crystal structures of the potential tridentate ligand formed from condensation of ferrocenoylacetone and S-benzyldithiocarbazate and its bivalent metal complexes

Article abstract of DOI:10.1016/j.poly.2003.10.003

A new potential tridentate ligand (H₂L) was synthesized from condensation of ferrocenoylacetone (C₅H₅FeC ₅H₄C(O)CH₂C(O)CH₃) with S-benzyldithiocarbazate in refluxing benzene. Reaction of the ligand (H ₂L) with a bivalent metal salt (M(OAc)₂·xH ₂O, M=Cu, Ni, Mn, Hg, Zn; SnCl₂·2H₂O) afforded the corresponding bivalent metal complexes M(HL)₂ (I, M=Cu; II, M=Ni; III, M=Mn; IV, M=Hg; V, M=Zn; VI, M=Sn). All the new compounds have been characterized by elemental analyses, ¹H NMR, IR and UV spectroscopies. A single-crystal X-ray analysis indicates that the ligand exists as a single iminone and not a tautomeric mixture of the iminone and enaminone. Crystallography of complex VI shows that the ligand acts as monoanionic tridentate coordinated to the tin atom via the carbonyl oxygen, deprotonated enamine nitrogen and thione sulfur atoms and the coordination geometry of the central metal is a distorted octahedron.

Full text of DOI:10.1016/j.poly.2003.10.003

Polyhedron 23 (2004) 567–573
www.elsevier.com/locate/poly
Syntheses and crystal structures of the potential tridentate
ligand formed from condensation of ferrocenoylacetone and
S-benzyldithiocarbazate and its bivalent metal complexes
a,
a
b
a
a
Yao-Cheng Shi *, Hua-Mei Yang , Hai-Bin Song , Chao-Guo Yan , Xiao-Ya Hu
a
School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, PR China
b
State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, PR China
Received 2 August 2003; accepted 14 October 2003
Abstract
A new potential tridentate ligand (H2L) was synthesized from condensation of ferrocenoylacetone (C5H5FeC5H4C(O)
CH2C(O)CH3) with S-benzyldithiocarbazate in refluxing benzene. Reaction of the ligand (H2L) with a bivalent metal salt
(M(OAc)2 ꢀ xH2O, M ¼ Cu, Ni, Mn, Hg, Zn; SnCl2 ꢀ 2H2O) afforded the corresponding bivalent metal complexes M(HL)2 (I,
M ¼ Cu; II, M ¼ Ni; III, M ¼ Mn; IV, M ¼ Hg; V, M ¼ Zn; VI, M ¼ Sn). All the new compounds have been characterized by el-
1
emental analyses, H NMR, IR and UV spectroscopies. A single-crystal X-ray analysis indicates that the ligand exists as a single
iminone and not a tautomeric mixture of the iminone and enaminone. Crystallography of complex VI shows that the ligand acts as
monoanionic tridentate coordinated to the tin atom via the carbonyl oxygen, deprotonated enamine nitrogen and thione sulfur
atoms and the coordination geometry of the central metal is a distorted octahedron.
ꢀ 2003 Elsevier Ltd. All rights reserved.
Keywords: Ferrocene; Dithiocarbazate; Ligand; Complex; Tin; Crystal structure
1. Introduction
C(CH3) ¼ NNHCSSCH2C6H5] (H2L) formed from
condensation of ferrocenoylacetone and S-ben-
zyldithiocarbazate and its bivalent metal complexes
[10,11].
N-substituted acid hydrazides are well-known to act
as chelating agents [1–4]. Furthermore, these com-
pounds and their metal complexes exhibit a broad
spectrum of biological, bactericidal and fungicidal ac-
tivities [5–7]. Since the discovery of ferrocene in 1951, it
has played an important role in developing a knowledge
of electronic structures of organometallic compounds
and materials chemistry. A considerable number of
ferrocene derivatives have been prepared directly or in-
directly from ferrocene and their properties have been
extensively studied. Among them, some have been re-
ported to display biological activity and act as b-lacta-
mase inhibitors [8,9]. In view of relatively few studies on
reactions of 1,3-diketones and acylhydrazides, here
we report the syntheses and crystal structures of
the potential tridentate ligand [C5H5FeC5H4C(O)CH2
2. Experimental
2.1. Reagents and general procedures
All chemicals were of analytical grade and used
without further purification. S-benzyldithiocarbazate
and ferrocenoylacetone were synthesized according to
the literature methods [12–14]. Progress of the reaction
was monitored by TLC (silica gel H). The 1H NMR
spectra were determined with a Bruker Avance 500
spectrometer using TMS as an external standard in
CDCl3. IR spectra were recorded on a Perkin–Elmer
402 as KBr disks in the range of 400–4000 cmꢁ1. UV
spectra were measured with a Shimadzu UV-240 spec-
trometer using a solution in DMF. Analyses for C, H
* Corresponding author. Tel/fax: +865147857939.
E-mail address: yzssyc@yzcn.net (Y.-C. Shi).
0277-5387/$ - see front matter ꢀ 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2003.10.003

568
Y.-C. Shi et al. / Polyhedron 23 (2004) 567–573
and N were performed on an Elementa Vario EL III
microanalytical instrument. Melting points were mea-
sured on a Yanagimoto apparatus and uncorrected.
Complex I as a black solid, yield: 0.847 g (88%). M.p.
131–132 ꢁC. Anal. Found: C, 54.54; H, 3.95; N, 5.42.
Calc. for C44H42Fe2N4O2S4Cu: C, 54.92; H, 4.40; N,
5.82%. IR (KBr disk): m(NH) 3435 (w, br), m(C@O) 1664
(vs), m(C@C) 1614 (m), m(C@S) 1070(s), m(C–S) 1019 (s),
m(N–N) 951 (m) cmꢁ1. UV (nm, in DMF): kmax (eꢂ
104, in dm3 molꢁ1 cmꢁ1) 265 (3.4) (B-band), 404 (4.5)
(K-band).
2.2. Synthesis of ligand
S-benzyldithiocarbazate (1.98 g, 10 mmol) was added
to a solution of ferrocenoylacetone (C5H5FeC5H4
C(O)CH2C(O)CH3) (2.7 g, 10 mmol) in 30 ml of ben-
zene, the mixture was refluxed for 5 h and then evapo-
rated to dryness and finally isolated by vacuum liquid
chromatography (VLC), using a mixed solvent of
CH2Cl2 and petroleum ether (v/v, 5:1) to afford the li-
gand. H2L as orange red crystals, yield: 3.51 g (78%).
M.p. 141–142 ꢁC. Anal. Found: C, 58.48; H, 4.58; N,
5.89. Calc. for C22H22FeN2OS2: C, 58.66; H, 4.93; N,
6.22%. 1H NMR (500 Mz, d, in CDCl3): iminone A
isomer (shown in Scheme 1), 2.18 (s, CH3), 3.73 (s,
SCH2), 3.94 (s, CH2), 4.23 (s, C5H5), 4.55, 4.82 (s, s, 3H/
4H and 2H/5H of C5H4 ring), 7.22–7.41 (m, C6H5), 6.54
(s, br, NH); enaminone B isomer (shown in Scheme 1),
Complex II as a dark red solid, yield: 0.536 g (56%).
M.p. 158–158.5 ꢁC. Anal. Found: C, 55.48; H, 4.08; N,
5.58. Calc. for C44H42Fe2N4O2S4Ni: C, 55.19; H, 4.42;
N, 5.83%. 1H NMR (500 Mz, d, in CDCl3): 1.83 (s, 6H,
2CH3), 4.37 (s, 4H, 2SCH2), 4.13 (s, 10H, 2C5H5), 4.19–
3
2
4.30, 4.63–4.69 (d, d, 4H, 4H, H/4H and H/5H of two
C5H4 rings), 5.28 (s, 2H, 2CH), 7.22–7.40 (m, 10H,
2C6H5), 8.28 ppm (s, 2H, 2NH). IR (KBr disk): m(NH)
3434 (m), m(C@O) 1663 (vs), m(C@C) 1534 (m), m(C@S)
1068 (s), m(C–S) 1028 (m), m(N–N) 966 (s) cmꢁ1. UV
(nm, in DMF): kmax (e ꢂ 104, in dm3 molꢁ1 cmꢁ1) 398
(2.0) (K-band), 624 (0.047) (R-band).
Complex III as a black purple solid, yield: 0.801 g
(84%). M.p. 192–193 ꢁC. Anal. Found: C, 54.90; H, 3.97;
N, 5.50. Calc. for C44H42Fe2N4O2S4Mn: C, 55.41; H,
4.41; N, 5.87%. IR (KBr disk): m(NH) 3427 (w, br),
m(C@O) 1529 (vs), m(C@C) 1519 (vs), m(C@S) 1062 (m),
m(C–S) 1020 (m), m(N–N) 965 (m) cmꢁ1. UV (nm, in
DMF): kmax (e ꢂ 104, in dm3 molꢁ1 cmꢁ1) 387 (1.64) (K-
band), 507 (0.052) (R-band).
Complex IV as a brown yellow solid, yield: 0.858 g
(78%). M.p. 137 ꢁC (dec.). Anal. Found: C, 47.77; H,
3.57; N, 4.77. Calc. for C44H42Fe2N4O2S4Hg: C, 48.05;
H, 3.85; N, 5.10%. IR (KBr disk): m(NH) 3434 (w),
m(C@O) 1666 (vs), m(C@C) 1614 (m), m(C@S) 1070 (m),
m(C–S) 1026 (m), m(N–N) 944 (s) cmꢁ1. UV (nm, in
DMF): kmax (e ꢂ 104, in dm3 molꢁ1 cmꢁ1) 328 (1.74),
360 (1.72) (K-band).
Complex V as an orange yellow solid, yield: 0.868 g
(90%). M.p. 192 ꢁC (dec.). Anal. Found: C, 54.80; H,
4.09; N, 5.54. Calc. for C44H42Fe2N4O2S4Zn: C, 54.81;
H, 4.39; N, 5.81%. IR (KBr disk): m(NH) 3434 (w),
m(C@O) 1666 (vs), m(C@C) 1622 (m), m(C@S) 1071 (m),
m(C–S) 1024 (m), m(N–N) 951 (m) cmꢁ1. UV (nm, in
DMF): kmax (e ꢂ 104, in dm3 molꢁ1 cmꢁ1) 265 (4.79),
277 (2.43) (B-band), 404 (3.74) (K-band).
2
2.07 (s, CH3), 3.54, 3.58, 3.83, 3.86 (q, JHH ¼ 18:6 Hz,
SCH2), 4.21 (s, C5H5), 4.68, 4.78 (s, s, 3H/4H and 2H/5H
of C5H4 ring), 5.73 (s, CH), 7.22–7.41 (m, C6H5), 9.82 (s,
NHCS2), 11.67 ppm (s, NH). IR (KBr disk): m(NH)
3431(w, br), m(C@O) 1665 (vs), m(C@N) 1637 (m), m
(C@S) 1068 (vs), m(C–S) 1035 (m), m(N–N) 984 (m)
cmꢁ1. UV (nm, in DMF): kmax (e ꢂ 104, in dm3 molꢁ1
cmꢁ1) 405 (1.8) (K-band), 553 (0.053) (R-band). Single
crystals of the ligand for X-ray determination were ob-
tained by slow evaporation of its solution in dichlo-
romethane and petroleum ether.
2.3. Syntheses of complexes
A solution of an appropriate metal acetate or
SnCl2 ꢀ 2H2O (0.5 mmol) in 5 ml of absolute ethanol was
added dropwise to a stirred solution of the ligand (H2L)
(0.45 g, 1 mmol) in 20 ml of absolute ethanol. The
mixture was stirred for 6 h at room temperature and
then filtered to afford the crude product. The resulting
solid recrystallized from dichloromethane and petro-
leum ether gave the corresponding complex (I to VI).
Complex VI as an orange solid, yield: 0.916 g (90%).
M.p. 238–239 ꢁC. Anal. Found: C, 51.72; H, 4.22; N,
5.41. Calc. for C44H42Fe2N4O2S4Sn: C, 51.94; H, 4.16;
N, 5.51%. 1H NMR (500 Mz, d, in CDCl3): 2.45 (s, 6H,
2
2CH3), 4.31, 4.34, 4.53. 4.56 (q, 4H, JHH ¼ 13:5 Hz,
2SCH2), 4.21 (s, 10H, 2C5H5), 4.37–4.39, 4.62–4.64 (d,
d, 4H, 4H, 3H/4H and 2H/5H of two C5H4 rings), 5.39 (s,
2H, 2CH), 7.31–7.43 (2m, 10H, 2C6H5), 7.28 ppm (s,
2H, 2NH). IR (KBr disk): m(NH) 3439(w, br), m(C@O)
1550 (s), m(C@C) 1515 (vs), m(C@S) 1051 (m), m(C–S)
1018 (m), m(N–N) 966 (m) cmꢁ1. UV (nm, in DMF):
kmax (e ꢂ 104, in dm3 molꢁ1 cmꢁ1) 400 (1.90) (K-band).
Scheme 1. Synthesis of ligand.

Y.-C. Shi et al. / Polyhedron 23 (2004) 567–573
569
Table 1
Crystallographic data for ligand and complex VI
Formula
C22H22FeN2OS2
C44H42Fe2N4O2S4Sn
Formula weight
Crystal size (mm)
Crystal system
450.39
0.30 ꢂ 0.25 ꢂ 0.20
1017.45
0.16 ꢂ 0.14 ꢂ 0.08
monoclinic
P21=n
triclinic
ꢁ
Space group
Unit cell dimensions
P1
ꢀ
a (A)
7.993(3)
10.503(4)
16.452(7)
10.819(5)
ꢀ
b (A)
ꢀ
c (A)
13.770(5)
108.573(6)
90.576(6)
23.932(10)
90.00
a (ꢁ)
b (ꢁ)
c (ꢁ)
101.065(8)
90.00
4180(3)
102.356(6)
1066.6(6)
3
ꢀ
V (A )
Z
2
1.402
4
1.617
Dc (g cmꢁ1
F (0 0 0)
T (K)
)
468
293(2)
0.917
2064
293(2)
l(Mo Ka) (mmꢁ1
Scan mode
)
1.521
/ and x scans
1.39–26.44
/ and x scans
1.57–26.44
ꢁ9 6 h 6 8, ꢁ9 6 k 6 13,
ꢁ17 6 l 6 16
6149
h Range (ꢁ)
Limiting indices
ꢁ20 6 h 6 20, ꢁ13 6 k 6 13,
ꢁ15 6 l 6 29
19,253
Reflections collected
Independent reflections
Number of parameters refined
Absorption correction
Final R indices [I > 2:0rðIÞ]
R indices (all data)
4318
279
8582
516
multi-scan
R ¼ 0:0496, Rw ¼ 0:1074
R ¼ 0:0923, Rw ¼ 0:1346
1.011
multi-scan
R ¼ 0:0562, Rw ¼ 0:1057
R ¼ 0:1452, Rw ¼ 0:1399
0.990
Goodness-of-fitF
Largest peak and hole (e A
ꢁ3
ꢀ
)
0.445 and )0.291
0.830 and )0.691
Single crystals of complex VI for X-ray determination
were obtained by slow evaporation of its solution in
dichloromethane and petroleum ether.
CCD diffractometer using graphite-monochromated Mo
ꢀ
Ka radiation (k ¼ 0:71073 A) at 293 K. Data collection
and reduction were performed using the SMART and
SAINT software [15]. An empirical absorption correction
2.4. Crystal structure determination
was applied using the SADABS program [16]. The
structures were solved by direct methods and refined by
full-matrix least-squares methods, based on F 2 with
anisotropic thermal parameters for all non-hydrogen
For each of compounds (H2L and VI), a selected
single crystal was mounted on a Bruker SMART 1000
Table 2
ꢀ
Selected bond distances (A) and angles (ꢁ) for ligand
Bond distances
Fe(1)–C(1)
Fe(1)–C(2)
Fe(1)–C(3)
Fe(1)–C(4)
Fe(1)–C(5)
Fe(1)–C(6)
Fe(1)–C(7)
Fe(1)–C(8)
Fe(1)–C(9)
Fe(1)–C(10)
2.027(3)
2.047(4)
2.056(4)
2.047(4)
2.033(4)
2.044(4)
2.029(5)
2.041(5)
2.051(4)
2.044(4)
N(1)–C(13)
N(2)–C(14)
N(1)–N(2)
O(1)–C(11)
C(1)–C(11)
C(11)–C(12)
C(12)–C(13)
S(1)–C(14)
S(1)–C(15)
S(2)–C(14)
1.271(5)
1.335(4)
1.395(4)
1.221(4)
1.472(5)
1.515(5)
1.508(5)
1.749(4)
1.820(4)
1.667(4)
Bond angles
C(1)–C(11)–C(12)
O(1)–C(11)–C(1)
O(1)–C(11)–C(12)
C(11)–C(12)–C(13)
C(12)–C(13)–C(22)
N(1)–C(13)–C(12)
116.8(3)
N(1)–C(13)–C(22)
N(2)–C(14)–S(1)
N(2)–C(14)–S(2)
S(2)–C(14)–S(1)
C(13)–N(1)–N(2)
C(14)–N(2)–N(1)
126.9(3)
121.4(3)
121.8(3)
112.9(3)
117.5(3)
115.6(3)
113.9(2)
121.4(3)
124.7(2)
117.4(3)
119.4(3)

570
Y.-C. Shi et al. / Polyhedron 23 (2004) 567–573
Table 3
ꢀ
Selected bond distances (A) and angles (ꢁ) for complex VI
Bond distances
Fe(1)–C(1)
Fe(1)–C(2)
Fe(1)–C(3)
Fe(1)–C(4)
Fe(1)–C(5)
Fe(1)–C(6)
Fe(1)–C(7)
Fe(1)–C(8)
Fe(1)–C(9)
Fe(1)–C(10)
Sn(1)–O(1)
Sn(1)–N(1)
Sn(1)–S(1)
N(1)–C(13)
N(2)–C(15)
N(1)–N(2)
O(1)–C(11)
C(11)–C(12)
C(12)–C(13)
C(13)–C(14)
S(1)–C(15)
S(2)–C(15)
S(2)–C(16)
2.010(7)
2.024(7)
2.027(7)
2.052(8)
2.022(8)
2.022(8)
2.021(10)
2.023(8)
2.027(8)
2.022(9)
2.069(5))
2.141(6)
2.481(2)
1.348(8)
1.280(8)
1.376(8)
1.310(8)
1.379(10)
1.379(9)
1.496(10)
1.736(7)
1.752(7)
1.816(8)
Fe(2)ndash;C(23)
Fe(2)–C(24)
Fe(2)–C(25)
Fe(2)–C(26)
Fe(2)–C(27)
Fe(2)–C(28)
Fe(2)–C(29)
Fe(2)–C(30)
Fe(2)–C(31)
Fe(2)–C(32)
Sn(1)–O(2)
Sn(1)–N(3)
Sn(2)–S(3)
2.026(7)
2.016(8)
2.045(8)
2.025(8)
2.019(7)
2.012(9)
2.054(9)
2.059(9)
2.032(9)
1.989(9)
2.061(5)
2.137(6)
2.487(2)
1.333(9)
1.262(9)
1.382(8)
1.311(8)
1.371(9)
1.407(10)
1.502(9)
1.745(8)
1.744(8)
1.801(8)
N(3)–C(35)
N(4)–C(37)
N(3)–N(4)
O(2)–C(33)
C(33)–C(34)
C(34)–C(35)
C(35)–C(36)
S(3)–C(37)
S(4)–C(37)
S(4)–C(38)
Bond angles
N(1)–Sn(1)–N(3)
O(1)–Sn(1)–O(2)
O(1)–Sn(1)–N(1)
O(1)–Sn(1)–N(3)
O(1)–Sn(1)–S(1)
O(2)–Sn(1)–N(1)
O(2)–Sn(1)–N(3)
O(2)–Sn(1)–S(3)
172.5(2)
Sn(1)–N(1)–N(2)
S(1)–Sn(1)–S(3)
S(1)–Sn(1)–N(1)
S(1)–Sn(1)–N(3)
S(1)–Sn(1)–O(2)
S(3)–Sn(1)–N(1)
S(3)–Sn(1)–N(3)
S(3)–Sn(1)–O(1)
118.3(4)
86.6(2)
85.8(2)
92.6(2)
97.06(8)
80.81(17)
100.50(16)
91.44(15)
106.88(16)
80.41(17)
87.98(15)
166.58(14)
86.9(2)
85.7(2)
164.80(15)
atoms and hydrogen atoms were included in the model
at their calculated positions and refined isotropically
using the SHELXTL program package [17]. Crystal
structure data and refinement details for both com-
pounds are summarized in Table 1. Selected bond dis-
tances and angles are given in Tables 2 (H2L) and 3 (VI).
ate in refluxing benzene via removal of water affords a
new ligand (H2L) as orange-red crystals. The ligand
(H2L) reacts with bivalent metal ions forming neutral
complexes M(HL)2 (I, M ¼ Cu; II, M ¼ Ni; III,
M ¼ Mn; IV, M ¼ Hg; V, M ¼ Zn; VI, M ¼ Sn). TLC
analysis of H2L shows, that it exists as an equilibrium
mixture of two isomers (major orange–red and minor
brown spots) in solution. However, it can crystallize in
an orange–red isomer. All complexes listed in Section 2
are soluble in polar organic solvents such as DMF, THF
and dichloromethane and insoluble in non-polar organic
solvents such as benzene, toluene and petroleum ether.
3. Results and discussion
3.1. Syntheses of ligand and its complexes
Syntheses of ligand and its complexes are shown in
Schemes 1 and 2. Reaction of ferrocenoylacetone (C5H5
FeC5H4C(O)CH2C(O)CH3) and S-benzyldithiocarbaz-
1
3.2. H NMR Spectra
The 1H NMR spectral data of ligand (H2L) and
complexes II and VI are listed in Section 2. Although H2L
contains the thioamide NHCS2 functional group, in
principle, it can exhibit thione–thiol tautomerism. How-
ever, its 1H NMR spectrum does not display any signal at
approximately 4.00 ppm due to the H–S proton, indi-
cating even in solution it exists as the thione tautomers
(iminone A and enaminone B isomers) as shown in
Scheme 1 [12], which is in agreement with the above TLC
2H2L + M(OAc)2
(HL)2M + 2HOAc
(M = Cu,Ni,Mn,Hg,Zn)
Ethanol
Scheme 2. Syntheses of complexes I–VI.
(HL) Sn + 2HCl

Y.-C. Shi et al. / Polyhedron 23 (2004) 567–573
571
analysis of H2L. Two methyl groups of tautomers A and
C19
C8
B exhibit two well-resolved singlets at d 2.18 and 2.07
ppm. According to relative intensities of both singlets,
two tautomers A and B exist in a 3:2 ratio in solution at
room temperature. For tautomer A, the protons of SCH2
and COCH2C moieties display two singlets at d 3.73 and
3.94 ppm. The substituted cyclopentadienyl ring shows
two singlets at d 4.55 and 4.82 ppm which are due to
protons of 3, 4- and 2, 5-positions, whereas a singlet at d
4.23 ppm is due to protons on the unsubstituted cyclo-
pentadienyl ring. The NH absorption appears at d 6.54
ppm as a broad peak [11,19]. For tautomer B, the protons
of COCH@C moiety displays a singlet at d 5.73 ppm
while the protons of SCH2 moiety exhibits a typical
doublet–doublet quartet (2JHH ¼ 18:55 Hz) [14,18]. The
substituted cyclopentadienyl ring shows two singlets at d
4.68 and 4.78 ppm which are due to protons of 3, 4- and 2,
5-positions, whereas a singlet at d 4.21 ppm is due to
protons on the unsubstituted cyclopentadienyl ring. The
NHCS2 (thioamide) and HN (enamine) absorptions ap-
pear at d 9.82 and 11.67 ppm, respectively [14,19]. For
both tautomers, benzene rings show three slightly-re-
solved multiplets at d 7.22–7.41 ppm.
C7
C18
C9
C21
C16
C6
C17
C4
C10
S1
Fe1
H12a
C12
C15
C5
H12b
C3
N1
C1
C13
N2
C2
C11
S2
O1
H2a
C22
Fig. 1. Crystal structure of ligand.
double bond. Therefore, the above data indicate, that
the bonding mode in the NNCS2CH2Ph moiety is very
similar to that in the S-benzyldithiocarbazate [22]. The
average distance of iron to carbon in the ferrocenyl
ꢀ
ꢀ
group is 2.042(4) A and very close to 2.045 A in ferro-
cene [23]. The mean C–C distances in the cyclopenta-
dienyl rings with and without the side-chain are 1.422(5)
ꢀ
ꢀ
and 1.403(7) A and also close to 1.41 A in ferrocene [23].
ꢀ
The distances of N(1) ꢀ ꢀ ꢀ S(1) (2.756(3) A) and
1
The H NMR spectral data of complexes II and VI
ꢀ
S(1) ꢀ ꢀ ꢀ S(2) (3.027 A) fall in the range of the sum of van
are characterized by the absence of the d 3.94 ppm signal
of COCH2C in the tautomer A or the d 11.67 ppm signal
of HN (enamine) in the tautomer B and the appear-
ance of the methine (CH) at d 5.28 and 5.39 ppm in
complexes II and VI [14]. Therefore, the above evidence
indicates that the ligand is deprotonated and bonded to
the metal ion, which is also supported by the crystal
structure of complex VI as described below. In addition,
all the signals of protons in complex II display high-field
shifts compared with those in the tautomer B, which
may be due to the increase of electron density resulting
from deprotonation and nickel-to-ligand feedback after
forming the planar–square complex [2,14].
der waals radii of the corresponding two atoms (3.35
ꢀ
and 3.6 A), which indicates that there is a weak inter-
action between the two atoms. Similarly, the distances of
S(2) ꢀ ꢀ ꢀ H(2A) and S(2) ꢀ ꢀ ꢀ H(22A) show the existence of
N(2)–H(2A) ꢀ ꢀ ꢀ S(2) and C(22)–H(22A) ꢀ ꢀ ꢀ S(2) intra-
molecular hydrogen bondings, whereas the O(1) ꢀ ꢀ ꢀ H(4)
distance displays an O(1) ꢀ ꢀ ꢀ H(4)–C(4) intermolecular
hydrogen bonding [24].
3.3.2. Crystal structure of complex VI
The crystal structure of the new tin complex VI to-
gether with the atomic numbering scheme is shown in
Fig. 2. The complex consists of two monoanionic tri-
dentate ligands (HLꢁ), each of which coordinates to the
Sn(II) ion via carbonyl oxygen, deprotonation enamine
3.3. Crystal structures of ligand and complex VI
3.3.1. Crystal structure of ligand
The crystal structure of the ligand together with the
atomic numbering scheme is shown in Fig. 1. The O(1)–
C9
C6
C8
C7
C14
N1
ꢀ
ꢀ
C(11) (1.221(4) A) and N(1)–C(13) (1.271(5) A) bond
distances indicate that these correspond to typical dou-
ble bonds [20,21], so the ligand in the solid state exists in
the form of the tautomeric iminone A. The N(1)–N(2)
Fe1
C4
C12
C13
C5
H2
C15
C16
S2
C11
S3
C3
C22
C1
C37
N2
Sn1
C33
C2
C44
S4
C43
C40
C18
C19
ꢀ
O1
bond distance is 1.395(4) A, which is slightly shorter
C42
C41
S1
ꢀ
than the single bond distance of 1.411(7) A [11,21]. The
C–S bond distances are 1.749(4) (S(1)–C(14)) and
ꢀ
1.820(4) A (S(1)–C(15)). Of the two distances, one is
ꢀ
close to the C–S distance of 1.81 A, while the other
shows an intermediate value between the single and
double bond distances, indicating partial double bond
N4
H4
C21
O2
C20
C38 C39
N3
C27
C23
C32
C35
C28
C26
Fe2
C34
C36
C31
C30
C24
C25
ꢀ
character. The S(2)–C(14) distance (1.667(4) A) is close
ꢀ
to the C@S distance of 1.69 A, suggesting that this is a
Fig. 2. Crystal structure of complex VI.

572
Y.-C. Shi et al. / Polyhedron 23 (2004) 567–573
nitrogen and thione sulfur (ONS donor set), viz.,
through the deprotonated tautomer B. The coordination
geometry of the central metal ion is a distorted octahe-
dron, the bond angle of N(1)–Sn–N(3) being 172.5(2)ꢁ.
The Sn–S, Sn–O and Sn–N bond distances are larger
than values reported for a related complex (2.458(3),
3.4. IR spectra
The important IR absorptions of the ligand (H2L) and
its complexes are given in Section 2. The ligand shows
bands at ca. 3169, 1665, 1637, 1068, 1035 and 983 cmꢁ1
which are assignable to m(NH), m(C@O), m(C@N),
m(C@S), m(C–S) and m(N–N), respectively. The m(C@N)
band disappears and new bands at 1513–1622 and 1220–
1287 cmꢁ1, which can be assigned to m(C@C) and m(C–N),
are observed. For complexes I, II, IV and V, the m(C@O)
band remains nearly unchanged, whereas for complexes
III and VI the corresponding band shows a significant
red-shift compared with the free ligand. These facts in-
dicate that the ligand possesses two bonding modes: as an
NS bidentate bonded to Cu, Ni, Hg and Zn ions and as an
ONS tridentate coordinated to Mn and Sn ions (N, de-
protonation enamine nitrogen and S, thione sulfur)
[12,14]. The ONS bonding mode has confirmed by the
above crystal structure of complex VI, however efforts to
grow single crystals of complex I, II, IV or V in order to
further support the NS bonding mode were unsuccessful.
ꢀ
2.396(3) and 2.187(4) A) [25].
A comparison of the bond distances within the co-
ordinated HLꢁ ligands shows extensive delocalization to
ꢀ
be present. The N–N bond at mean 1.379(8) A, which is
singnificantly shorter than the single bond distance of
ꢀ
1.411(7) A, is observed to have some double bond
character [12,21]. More double bond character is present
in the C–N bond of the HNCS2 moiety as judged from
ꢀ
its bond distance of mean 1.271(8) A. This very clearly
indicates a pronounced lone pair delocalization between
carbon and nitrogen, namely the p–p conjugation. More
interestingly, formal C@S and C–S bonds in the HNCS2
moiety also display marked electron delocalization
[12,21]. The C–N bond distances (1.348(8) and 1.333(9)
ꢀ
A) in the CH@C(CH3)N moiety are close to the value of
ꢀ
the C–N single bond (1.335(4) A) of the HNCS2 moiety
in the free ligand while the C@O bonds are longer than
the corresponding bond in the free ligand [20,21]. In
addition, delocalization evidence is further supported by
the fact that the hybridized states of C (attached to N
and O atoms) and N atoms are all sp2. Although that
the protons of thioamide NHCS2 functional groups are
not removed on complexation are unusual, similar cases
also appear in two metal complexes of thiosemicarba-
zone and dithiocarbazate ligands [26,27]. The average
3.5. UV spectra
The UV spectral data of the ligand (H2L) and its
complexes are listed in Section 2. The UV spectrum of
the ligand shows two absorptions at 405 and 553 nm,
which are attributable to the K-band of the skelton
[C(O)CH@C(CH3)N] and the R-band (n fi p* transi-
tion) [12,18,21]. For complex I, the shortest wavelength
absorption which is assigned as the B-band of the ben-
zene and cyclopentadienyl rings. However, complex V
exhibits two B-bands of the benzene and cyclopenta-
dienyl rings. Interestingly, the K-bands in all complexes
show hypsochromic shifts compared with that of the
free ligand [2].
ꢀ
distance of iron to carbon (2.026(7) A) and mean C–C
distances with and without side-chains (1.42(1) and
ꢀ
1.39(1) A) in the ferrocenyl groups are all shorter than
those in the free ligand [2]. The distance of
ꢀ
N(2) ꢀ ꢀ ꢀ H(16B) (2.43 A) indicates that there is the
C(16)–H(16B) ꢀ ꢀ ꢀ N(2) intramolecular hydrogen bond-
ing in complex VI. It is more noted that although it
contains the NH group no intermolecular hydrogen
bonding about the NH group in complex VI is observed
because of the steric hindrance from the methyl and
benzyl groups. However, the S(2) ꢀ ꢀ ꢀ H(36A) distance
4. Summary and conclusions
Reaction of ferrocenoylacetone and S-benzyldithioc-
arbazate yields a new ligand (H2L). The ligand exists as
a single iminone in the solid state while as a tautomeric
mixture of the iminone and enaminone (3:2) in solution.
ꢀ
(2.85 A) may display a weak S(2) ꢀ ꢀ ꢀ H(36A)–C(36) in-
termolecular hydrogen bonding [24].
Fc
Fc
H3C
H3C
NH
O
N
O
NH
N
PhCH2S
PhCH2S
S
S
M
S
M
S
SCH2Ph
SCH2Ph
O
N
NH
O
N
NH
CH3
Fc
CH3
Fc
( M=Mn,Sn )
( M=Cu,Ni,Hg,Zn )
Fig. 3. Proposed structures of complexes.

Y.-C. Shi et al. / Polyhedron 23 (2004) 567–573
573
[4] D.X. West, M.M. Salberg, G.A. Bain, A.E. Liberta, Transition
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Upon coordinating to the bivalent metal ion, the ligand
exhibits two bonding modes (NS and ONS donor sets).
In complexes I, II, IV and V (I, M ¼ Cu; II, M ¼ Ni; IV,
M ¼ Hg; V, M ¼ Zn), the ligand acts as a monoanionic
bidentate coordinated to the metal ion via the deprot-
onated enamine nitrogen and thione sulfur atoms (NS
donor set) whereas in complexes III and VI (III,
M ¼ Mn; VI, M ¼ Sn) as a monoanionic tridentate via
the carbonyl oxygen, deprotonated enamine nitrogen
and thione sulfur atoms (ONS donor set). Suggested
structures for new complexes are shown in Fig. 3.
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5. Supplementary material
Full crystallographic data (CCDC No. 213725 for
ligand and CCDC No. 211558 for complex VI) have
been deposited at the Cambridge Crystallographic Da-
tabase Centre and are available on request from the
Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (fax: +44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk or http//www.ccdc.cam.ac.uk).
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Y.C. Shi thanks the National Nature Science Foun-
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