Synthesis, crystal structures and multinuclear NMR spectroscopy of copper(I) complexes with benzophenone thiosemicarbazone

Article abstract of DOI:10.1016/j.poly.2006.04.006

Reactions of benzophenone thiosemicarbazone (Hbztsc, Ph₂C{double bond, long}N-NH-C({double bond, long}S)-NH₂) with copper(I) chloride/bromide in the presence of two moles of PPh₃, formed monomeric tetrahedral complexes, [CuX (η¹-S-Hbztsc)(PPh₃)₂] · CH₃CN (X = Cl, 1; Br, 2). It did not form similar complex with copper(I) iodide; rather it formed a trigonal planar complex [CuI(η¹-S-Hbztsc)₂] (3) with two moles of Hbztsc in absence of PPh₃. All the complexes have been characterized with the help of elemental analyses, IR, ¹H, ¹³C, and ³¹P NMR spectroscopy, and single crystal X-ray crystallography. The crystal structure of ligand is also described. In all the complexes, benzophenone thiosemicarbazone is acting as a neutral S donor ligand in η¹-S bonding mode. NMR data support that the complexes remain stable in solution phase.

Full text of DOI:10.1016/j.poly.2006.04.006

Polyhedron 25 (2006) 2755–2763
www.elsevier.com/locate/poly
Synthesis, crystal structures and multinuclear NMR spectroscopy
of copper(I) complexes with benzophenone thiosemicarbazone
a,
a
b
c
c
Tarlok S. Lobana *, Sonia Khanna , Ray J. Butcher , A.D. Hunter , M. Zeller
a
Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005, India
b
Department of Chemistry, Horward University, Washington, DC 20059, USA
Department of Chemistry, 1 University Plaza, Youngstown State University, Youngstown, OH 44555 3663, USA
c
Received 21 February 2006; accepted 2 April 2006
Available online 25 April 2006
Abstract
Reactions of benzophenone thiosemicarbazone (Hbztsc, Ph2C@N-NH-C(@S)-NH2) with copper(I) chloride/bromide in the presence
of two moles of PPh3, formed monomeric tetrahedral complexes, [CuX (g1-S-Hbztsc)(PPh3)2] Æ CH3CN (X = Cl, 1; Br, 2). It did not
form similar complex with copper(I) iodide; rather it formed a trigonal planar complex [CuI(g1-S-Hbztsc)2] (3) with two moles of Hbztsc
in absence of PPh3. All the complexes have been characterized with the help of elemental analyses, IR, 1H, 13C, and 31P NMR spectros-
copy, and single crystal X-ray crystallography. The crystal structure of ligand is also described. In all the complexes, benzophenone
thiosemicarbazone is acting as a neutral S donor ligand in g1-S bonding mode. NMR data support that the complexes remain stable
in solution phase.
Ó 2006 Elsevier Ltd. All rights reserved.
1. Introduction
(mode D) [25] (Scheme 1) and in the anionic form, there is
only N2,S-chelation-cum S-bridging (mode E) [27].
The chemistry of thiosemicarbazones has received con-
siderable attention in view of their variable bonding modes,
promising biological implications, structural diversity and
ion sensing ability [1–7]. Another reason is easy access to
their synthesis by modifying parent aldehyde or ketone used
for synthesis or by substitution at C2 or N1 atoms. Chart 1
shows various bonding modes of neutral thiosemicarbaz-
ones. As regards biological implications, thiosemicarbazone
complexes of copper(II) have been intensively investigated
for antiviral, antibacterial, antitumour, and antifungal
activity and inhibitory action is attributed to their chelating
properties [8–18]. While structural chemistry of copper(II)
has been well investigated [20], corresponding complexes
of copper(I) are limited [19–27]. In case of copper(I), neutral
thiosemicarbazones have exhibited different bonding
modes: g1-S (mode A) [19–24], l2-S (mode B) [24a], N3,S-
chelation (mode C) [25,26], N3,S-chelation-cum-S-bridging
In the literature, the reported complexes of thiosemicar-
bazones have R = Ph, pyridyl, CH3, etc. and R0 = H, CH3,
etc. (Chart 2) [1–4,8–41]. In other words, there is no com-
plex of copper(I) structurally characterized with both R and
R0 = Ph, or any other aryl group [8–18]. In the present work,
we report the synthesis, multinuclear NMR spectroscopy
and crystal structures of copper(I) halide complexes, [CuCl-
(g1-S-Hbztsc)(PPh3)2] (1), [CuBr(g1-S-Hbztsc) (PPh3)2] (2)
and trigonal complex [CuI(g1-S-Hbztsc)2] (3). The crystal
structure of ligand is also reported.
2. Experimental
2.1. Materials and techniques
Copper(I) halides were prepared by reducing an aqueous
solution of CuSO4 Æ 5H2O with SO2 in the presence of NaX
(X = Cl, Br, I) in H2O [42]. Ph3P was procured from Aldrich
Chemicals Ltd. and used as such. C, H and N analysis
were obtained with Thermoelectron FLASHEA1112 CHNS
*
Corresponding author. Tel.: +91 183 257604; fax: +91 183 2 258820.
E-mail address: tarlokslobana@yahoo.co.in (T.S. Lobana).
0277-5387/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2006.04.006

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T.S. Lobana et al. / Polyhedron 25 (2006) 2755–2763
(Ph). 13C NMR (CDCl3, d ppm, J, Hz): 178.8 (C1); 151.0
NH2
NH2
M
N3
S
(C2); 136.3, 131.0 (C3); 130.3, 130.23 (C6); 129.86, 127.7
(C4,8); 128.4 (C5,7).
N3
N2
C
S
C
S
S
S
M
M
M
M
M
M
M
M
(A)
2.3. Synthesis of complexes
(E)
(D)
(C)
Chart 1.
(B)
2.3.1. [CuCl(g1-S-Hbztsc)(PPh3)2] Æ CH3CN (1)
To a solution of CuCl (0.025 g, 0.25 mmol) in dry aceto-
nitrile (15 mL) was added solid Hbztsc (0.064 g,
0.25 mmol) and the contents were stirred for 3 h at room
temperature. During stirring, a yellow solid formed was
separated. To this solid suspended in acetonitrile was
added PPh3 (0.132 g, 0.50 mmol) and stirring was contin-
ued for further 1 h followed by refluxing for 10 min. Clear
light yellow solution formed was filtered and allowed to
evaporate at room temperature. Slow evaporation of solu-
tion gave clear light yellow crystals. Complex is soluble in
chloroform, dichloromethane and hot acetonitrile (60%,
m.p. 182–184 °C). Anal. Calc. for C50H43ClCuN3P2S Æ
CH3CN: C, 67.83; H, 5.00; N, 6.08. Found: C, 67.58; H,
5.04; N, 5.52%. Main IR peaks (KBr, cmꢀ1): m(N–H)
3336 s, 3238 m (–NH2–), 3144 m (–NH–); 1602 m, 1585
sh m(C@N) + d(NH2) + m(C@C); 1072 s, 1024 s, 841 s (thi-
oamide moiety); 1093 s m(P–CPh). 1H NMR (CDCl3, d
ppm) 9.11 b (–N2H), 8.57 s, 6.91 s (–N1H2), 7.29–7.69 m
(Ph + PPh3). 13C NMR (CDCl3, d ppm, J, Hz) 176.9
(C1); 157.9 (C2); 136.3, 131.1 (C3); 130.4 (C6); 129.8,
127.8 (C4,8); 128.6 (C5,7); 133.9 (i-C, PhP); 133.9 (o-C,
2 PPh3
CuX + Hbztsc
CuI + 2 Hbztsc
[CuX(Hbztsc)(PPh3)2]
CH3CN
X = Cl (1), Br(2)
CH3CN
[CuI(Hbztsc)2]
(3)
Scheme 1.
5
8
6
4
3
2
2
NH
NH
S
R
1
C
7
S
3
N
2
1
C
3
N
2
C
C
R'
1
H2N
1
H2N
Hbztsc
Chart 2.
analyzer. Infrared spectra were recorded as KBr pellets in
the range 4000–200 cmꢀ1 on Pye–Unicam SP-3-300 spectro-
photometer. The melting points were determined with a
JP–C = 15.1, PhP); 129.4 (p-C, PhP); 128.4 (m-C, JP–C
=
8.8, PhP). 31P NMR (CDCl3, d ppm): ꢀ112.16 ppm,
Dd(dcomplex ꢀ dligand) = 0.991 ppm. Compound 2 was pre-
pared in the similar manner.
1
Gallenkamp electrically heated apparatus. H NMR were
recorded on a JEOL AL-300 FT spectrometer operating at
a frequency of 300 MHz using CDCl3 as solvent with
TMS as internal reference. 13C NMR spectra were recorded
at a frequency of 200 MHz using CDCl3 as solvent and TMS
as an internal reference. 31P NMR spectra were recorded on
a Bruker ACP-300 spectrometer operating at a frequency of
121.5 MHz with (CH3O)3P as external reference set at zero
value.
2.3.2. [CuBr(g1-S-Hbztsc)(PPh3)2] Æ CH3CN (2)
Crystals were grown from an acetonitrile solution at
room temperature. Complex is soluble in chloroform,
dichloromethane and hot acetonitrile (61%, m.p. 184–
186 °C). Anal. Calc. for C50H43BrCuN3P2S Æ CH3CN: C,
64.70; H, 4.76; N, 5.80. Found: C, 64.82; H, 5.15; N,
5.31%. Main IR peaks (KBr, cmꢀ1): m(N–H) 3344 s, 3236m
(–NH2–), 3157 m (–NH–); 1602 s, 1585 m m(C@N) +
d(NH2) + m(C@C); 1025 s, 837 s (thioamide moiety); 1091
2.2. Preparation of ligand (Hbztsc)
To a solution of thiosemicarbazide (2.5 g, 0.027 mol) in
hot distilled water (50 mL) and glacial acetic acid (5 mL),
was slowly added benzophenone (4.99 g, 0.027 mol) dis-
solved in methanol (30 mL). The contents were refluxed
for 30 h. and the clear solution containing yellowish orange
oily layer, was poured in a beaker and stirred vigorously
with a glass rod. The yellow solid formed was dried and
recrystallised using methanol. Slow evaporation of the
solution gave clear yellow crystals. (25%, m.p. 160–
162 °C). Anal. Calc. for C14H13N3S: C, 65.79; H, 5.09; N,
16.45. Found: C, 65.66; H, 4.93; N, 16.25%. Main IR peaks
(KBr, cmꢀ1): m(N–H) 3412 s, 3346 s, 3247 m, (–NH2–) 3151
s (–NH–); 1608b, 1437b m(C@N) + dNH2 + m(C@C); 1070
1
s m(P–CPh). H NMR (CDCl3, d ppm) 9.02 b (–N2H), 8.46
s (–N1H2), 7.20–7.66 m (–N1H2 + Ph + PPh3). 13C NMR
(CDCl3, d ppm, J, Hz) 176.6 (C1); 151.7 (C2); 136.3, 131.1
(C3); 130.4 (C6); 129.5, 127.8 (C4,8); 128.5 (C5,7); 133.4 (i-
C, PhP), 133.9 (o-C, JP–C = 14.7, PhP ),129.4 (p-C, PhP),
128.4 (m-C, JP–C = 9.1, PhP). 31P NMR (CDCl3, d ppm):
ꢀ112.73, Dd(dcomplex ꢀ dligand) = 0.427 ppm.
2.3.3. [CuI(g1-S-Hbztsc)2] (3)
To a solution of CuI (0.025 g, 0.13 mmol) in dry aceto-
nitrile (20 mL) was added solid Hbztsc (0.067 g,
0.26 mmol) and contents were stirred for 4 h. Clear yellow
solution was filtered and allowed to evaporate at room
temperature. Slow evaporation of solution gave clear
1
s, 1026 s, 846 s (thioamide moiety). H NMR (CDCl3, d
ppm) 8.68 (–N2H), 7.81 s, 6.45 sb (N1H2), 7.27–7.61 m

T.S. Lobana et al. / Polyhedron 25 (2006) 2755–2763
2757
yellow crystalline needles. Complex is soluble in chloro-
form, dichloromethane and hot acetonitrile. (68.5%, m.p.
210–212 °C). Anal. Calc. for C28H26CuIN6S2: C, 47.92;
H, 3.71; N, 11.98. Found: C, 48.53; H, 3.84; N, 11.81%.
Main IR peaks (KBr, cmꢀ1): m(N–H) 3390 s, 3346 s, 3223
m (–NH2–) 3149 s (–NH–); 1595 sh, 1583 m, 1500 m
m(C@N) + d(NH) + m(C@C); 1072 s, 1026 s, 831 s (thioam-
ide moiety). 1H NMR (CDCl3, d ppm), 8.78 s (–N2H), 8.06
sb (–N1H2), 7.28–7.60 m (N1H2 + Ph).
formed an insoluble product of stoichiometry {CuX-
(Hbztsc)} which after addition of two moles of PPh3 yielded
a monomeric tetrahedral complex [CuX(Hbztsc)(PPh3)2]
(X = Cl, 1; Br, 2) (Scheme 1). Reaction of copper(I) iodide
with Hbztsc in the presence of two moles of PPh3 did not
form similar complex, rather it formed a known cubane
complex, {Cu4I4(PPh3)4}. However copper(I) iodide with
Hbztsc in MeCN in the absence of PPh3, formed a trigonal
complex [CuI(Hbztsc)2] (3). All these complexes have melt-
ing points in the range of 182–210 °C. Complexes 1 and 2
are readily soluble in chloroform while 3 is sparingly
soluble.
2.4. X-ray crystallography
Suitable light yellow crystals of Hbztsc and com-
pounds 1, 2 and 3 were mounted on an automatic Enraf
Nonius CAD-4 diffractometer equipped with graphite
The IR spectra of ligand (Hbztsc) shows m(N–H) in the
range of 3412–3247 cmꢀ1 (–NH2) and at 3151 s (–NH–).
In all the complexes, m(N–H) ranges from 3390–
3236 cmꢀ1 (–NH2) and 3160–3140 cmꢀ1 (–NH–). It sug-
gests the neutral monodentate (g1-S) nature of ligand
Hbztsc. The thioamide bands m(C–S) + m(C–N) appear in
the range of 846–1085 cmꢀ1 in Hbztsc. These modes appear
in the region of 830–1090 cmꢀ1 in the complexes. Medium
to broad peaks appear at 1608 b, 1473 b cmꢀ1 in free ligand
corresponding to m(C@N), d(NH2) and m(C@C). However,
they appear in the range of 1500–1605 cmꢀ1 in all the com-
plexes. A characteristic m(P–CPh) peak at 1093 s cmꢀ1 in (1)
and 1091 s cmꢀ1 in (2) confirms the presence of PPh3 in the
coordinated form in the complexes.
˚
monochromator and Mo Ka radiation (k = 0.71073 A).
The unit cell dimensions and intensity data were mea-
sured at 93 K for Hbztsc, 1, 2 and 100 K for 3. The
structures were solved by direct methods and refined by
full matrix least squares method based on F2. All nonhy-
drogen atoms were refined anisotropically using XCAD-
49 (data reduction) and SHELXL. The hydrogen atoms
were calculated using structure factor calculations in their
idealized positions. The crystallographic data is summa-
rized in Table 1.
3. Results and discussion
3.2. Crystal structures of ligand and complexes 1–3
3.1. Synthesis and infrared spectroscopy
The atomic numbering schemes for molecular structures
of ligand and complexes 1, 2 and 3 are shown in Figs. 1–4
and the selected bond lengths and angles are given in
Table 2.
Reaction of copper(I) chloride/copper(I) bromide with
benzophenone thiosemicarbazone (Hbztsc, Ph2C@N–
NH–C(@S)–NH2) in the molar ratio of 1:1 in MeCN
Table 1
Crystallographic data for compounds 1, 2, 3 and ligand
1
2
3
Empirical formula
MW
C
50H43ClCuN3P2S Æ CH3CN
C50H43BrCuN3P2S Æ CH3CN
C28H26CuIN6S2
701.11
yellow
monoclinic
P2/c
16.4147(14)
6.1106(17)
31.3870(7)
2893.2(8)
90
113.22
90
4
1.610
1.995
919.92
yellow
triclinic
964.38
yellow
triclinic
Crystal colour
Crystal system
Space group
ꢀ
ꢀ
P1
P1
˚
a (A)
12.3639(8)
13.9423(8)
14.8040(9)
2255.8(2)
113.9130(10)
100.6420(10)
94.9190(10)
2
10.356(7)
14.480(11)
17.684(13)
2311(3)
66.206(12)
79.346(14)
72.729(13)
2
˚
b (A)
˚
c (A)
3
˚
V (A )
a (°)
b (°)
c (°)
Z
D (Mg mꢀ3
l(Mo Ka) (mmꢀ1
)
1.354
0.702
1.386
1.492
)
Reflections collected
Unique reflections, Rint
Final R indices
18082
10732, 0.0450
0.0490, 0.1006
18915
10975, 0.0365
0.0502, 0.114
10863
10897, 0.0000
0.0379,
0.0937
R1 and wR2
3
˚
˚
˚
˚
Crystal data for
C
14H13N3S: 255.33; monoclinic; C2/c; a = 26.5443(16) A; b = 6.0935(4) A; c = 16.7931(10) A; V = 2649.2(3) A ; a = 90°;
b = 102.7580(10)°; c = 90°; V = 2649.2(3) A ; Z = 8; D = 1.280 Mg mꢀ3; l(Mo Ka) (mmꢀ1) = 0.229; reflections collected = 9934; unique reflec-
3
˚
tions = 3227; Rint = 0.0297; R = 0.0453.

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T.S. Lobana et al. / Polyhedron 25 (2006) 2755–2763
Fig. 1a. The structure of ligand (Hbztsc) with numbering scheme.
Fig. 2b. Packing diagram of [CuCl(g1-S-Hbztsc)(PPh3)2] Æ CH3CN (1).
3.2.1. Ligand
The ligand (Hbztsc) crystallized in the monoclinic space
group C2/c. The S and the hydrazinic N(3) atoms are trans
with respect to C(1)–N(2) bond and thus ligand has E con-
˚
figuration. The C(1)–S bond distance, 1.6866(17) A is close
˚
to a double bond, and comparable with ca.1.69 A in salicyl-
aldehyde thiosemicarbazone and 2-hydroxyacetophenone
[43,44]; other bonds, C(2)–N(3), C(1)–N(1), C(1)–N(2),
N(2)–N(3) are also comparable with the literature data
Fig. 1b. Packing diagram of the ligand (Hbztsc).
Fig. 2a. The structure of [CuCl (g1-S-Hbztsc)(PPh3)2] Æ CH3CN (1) with numbering scheme.

T.S. Lobana et al. / Polyhedron 25 (2006) 2755–2763
2759
Fig. 3a. The structure of [CuBr(g1-S-Hbztsc)(PPh3)2] Æ CH3CN (2) with numbering scheme.
Fig. 3b. Packing diagram of [CuBr(g1-S-Hbztsc)(PPh3)2] Æ CH3CN (2).
[43–45]. There is a moderately strong intermolecular N(1)–
3.2.2. Complexes 1–3
H(1B)ꢁ ꢁ ꢁS* bond [2.49 A] {cf. sum of van der Waals radii of
Complexes 1 and 2 have the triclinic space groups, while
complex 3 has monoclinic space group. The E-configura-
tion of free ligand is unchanged in the complexes. In com-
plex 1, copper is bonded to one S atom of the ligand
˚
˚
H and S, 3.0 A [46]} and a long range C–HPhꢁ ꢁ ꢁS intermo-
lecular hydrogen bonding leading to formation of dimer as
shown in Fig. 1b.

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T.S. Lobana et al. / Polyhedron 25 (2006) 2755–2763
Fig. 4a. The structure of [CuI(g1-S-Hbztsc)2] (3) with numbering scheme.
Fig. 4b. Packing diagram of [CuI(g1-S-Hbztsc)2] (3).
amino group is engaged in intramolecular –HN1Hꢁ ꢁ ꢁCl
hydrogen bonding while other hydrogen is involved in
intermolecular –HN1Hꢁ ꢁ ꢁCl hydrogen bonding forming a
dimer (Fig. 2b). Similar trend of bonding is seen in complex
2 except for the presence of additional long range
C–HPh(Hbztsc)ꢁ ꢁ ꢁBr contact resulting in the formation of
8 membered ring in the center of the dimer. Two molecules
of CH3CN are present as solvent of crystallization per unit
cell in the crystal packing but are not involved in any sort
of hydrogen bonding at all and also do not appear in the
analysis (Fig. 3b). However, in complex 3, one hydrogen
of amino group is engaged in intramolecular –HN1Hꢁ ꢁ ꢁI
hydrogen bonding while other hydrogen remains free. In
addition, long range intermolecular C–HPh(Hbztsc)ꢁ ꢁ ꢁS
hydrogen bonding is present forming a dimer (Fig. 4b).
A comparison of P–Cu–P, S–Cu–X and Cu–S–C bond
angles is made for various CuI-complexes with analogous
thiosemicarbazones (Table 4). The groups at C2 carbon
appear to play significant role in affecting the above angles
which are correlated with the electronegativity of halogen
atoms. When py, H (4–6) [24a] ; and Ph, H (7, 8) [24a]
are bonded to C2 carbon, angles Cu–S–C and S–Cu–X
increase with change in X from chloride to iodide; and
the corresponding P–Cu–P bond angles decrease. The
halogens are engaged in intramolecular –N2Hꢁ ꢁ ꢁX, or
–N1H2ꢁ ꢁ ꢁX hydrogen bonds and strengths of these bonds
obviously vary with the electronegativity of halogen atoms.
Chart 3 exhibits how the amino and imino hydrogen atoms
˚
(Hbztsc) with Cu–S bond distance of 2.3606(8) A; two P
˚
atoms from PPh3 ligands {Cu–P(1), 2.2665(8) A; Cu–
P(2), 2.2505(8) A}, and one chlorine atom at Cu–Cl bond
distance of 2.3757(7) A. Complex 2 has similar bond
parameters, viz., Cu–S, 2.3542(17) A; Cu–P(1), 2.2749
(17) A; Cu–P(2), 2.2552(16) A; Cu–Br, 2.4863(12) A. The
angles around Cu lie in the ranges, 102.55(3)–126.00(3)°
and 99.49(6)–131.56(4)° in compounds 1 and 2, respec-
tively, with P(2)–Cu–P(1) being the largest, and P(2)–Cu–
X {X = Cl, Br} being the smallest. This reveals a distorted
tetrahedral geometry around Cu atom in both the com-
plexes. Finally in complex 3, each Cu is bonded to two S
atoms of two Hbztsc ligands with Cu–S distances of
˚
˚
˚
˚
˚
˚
˚
2.2269(7), 2.2321(7) A, and to one iodine atom with Cu–I
bond distance of 2.5441(4) A. The angles around Cu range
from 118.95(2)° to 121.42(2)°, indicating a trigonal geome-
try around copper center. The C–S bond distances in these
˚
`
complexes are marginally longer vis-a-vis free ligand, and
reveal weakening of pp–pp bond. It may be noted that
trends of variation in Cu–P, Cu–S and C–S distances are
analogous to the literature values [19,21,24a]. The absence
of PPh3 in trigonal planar complex 3 makes a stronger Cu–
S bond. Further, Cu–X distances in the complexes are
much lesꢀs than the sum ofꢀthe ionic radii oꢀf Cu+ and Xꢀ
+
+
+
˚
˚
˚
(Cu , Cl , 2.58 A; Cu , Br , 2.73 A; Cu , I , 2.97 A [46]).
In the solid state, amino (–HN1H) hydrogen atom of
thiosemicarbazone is involved in hydrogen bonding in all
the complexes (Table 3). In complex (1), one hydrogen of

T.S. Lobana et al. / Polyhedron 25 (2006) 2755–2763
2761
Table 2
are involved in hydrogen bonding with halogens. A stron-
ger –N2Hꢁ ꢁ ꢁX or –N1H2ꢁ ꢁ ꢁX hydrogen bond shortens the
Cu–S–C bond angle, which leads to opening of P–Cu–P
angle. The trend for p-HOC6H5, H groups (9, 10) [21]
bonded to C2 is similar except for S–Cu–X which decreased
and this may be due to the packing effect or presence of sol-
vent of crystallization. Due to rigidity of isatin groups (11,
12) [19], the above trends are less significant.
˚
Selected bond distances (A) and bond angles (°) for ligand (Hbztsc) and
complexes 1, 2 and 3
Bond distances
Hbztsc
S–C(1)
N(1)–C(1)
N(2)–C(1)
N(2)–N(3)
1.6866(17)
1.321(2)
1.358(2)
N(3)–C(2)
C(2)–C(3)
C(2)–C(9)
1.289(2)
1.496(2)
1.481(2)
1.3766(19)
The most significant observation is found when two Ph
groups are bonded to C2 carbon. Both Cu–S–C and S–Cu–
X angles increase as noted for above complexes. However,
P–Cu–P angle increases with change in halide from chloride
(121°) to bromide (131°) in complexes 1 and 2, unlike the
expected decreasing trend. The increased P–Cu–P bond
angle in complex 2 is due to the steric effect of two Ph groups
at C2 carbon with large bromide group. In case of still bulky
iodide group in complex 3, this steric effect becomes very
large and this explains lack of formation copper(I) iodide
complex containing PPh3 ligands similar to 1 or 2.
1
Cu–S
2.3606(8)
2.2665(8)
2.2505(8)
2.3757(7)
1.702(3)
1.314(3)
N(2)–C(1)
N(2)–N(3)
N(2)–C(2)
C(2)–C(3)
C(2)–C(9)
1.351(3)
1.374(3)
1.296(4)
1.479(4)
1.495(4)
Cu–P(1)
Cu–P(2)
Cu–Cl
S–C(1)
N(1)–C(1)
2
Cu–S
2.3542(17)
2.2749(17)
2.2552(16)
2.4863(12)
1.699(4)
N(2)–C(1)
N(2)–N(3)
N(3)–C(2)
C(2)–C(3)
C(2)–C(9)
1.395(4)
1.357(4)
1.291(5)
1.499(5)
1.513(5)
Cu–P(1)
Cu–P(2)
Cu–Br
S–C(1)
N(1)–C(1)
3.3. NMR spectroscopy
1.292(5)
The 1H NMR of ligand Hbztsc in CDCl3 shows a singlet
at 8.68 ppm (N2H), which shifted downfield to 9.11 ppm in
complex 1, 9.02 ppm in complex 2 and 8.78 ppm in com-
plex 3. This is in accordance with the coordination behav-
iour of thiosemicarbazones [24a], and its presence in the
spectra of complexes indicates that N2H protons are not
deprotonated. The N1H2 protons of free ligand Hbztsc
exhibit two sets of signals, one broad peak (unresolved)
at 6.45 ppm and a doublet at 7.81 ppm. This can be attrib-
uted to the restricted rotation about C1–N1 bond axis due
to delocalization of lone pairs of electrons on N1H2 nitro-
gen. A pair of broad signals corresponding to N1H2 pro-
tons appear downfield at 6.91 ppm and 8.56 ppm in
complex 1. However, a single broad signal is observed at
8.47 ppm in complex 2 and 8.06 ppm in complex 3. The sec-
ond signal is probably obscured by the protons of phenyl
rings. This may be attributed to intermolecular as well as
intramolecular –HN1Hꢁ ꢁ ꢁX (X = Cl, Br, I) hydrogen
bonding in the solid state which may be operative even in
the solution phase. The phenyl protons in free ligand show
a series of multiplets in the region of 7.27–7.61 ppm. Ph3P
signals in the complexes merged with the signals of phenyl
protons of ligand and show a series of doublets and multi-
plets in the region of 7.29–7.69 ppm in 1 and 7.20–
7.66 ppm in 2. In complex 3, phenyl protons appeared
unchanged at 7.28–7.60 ppm.
3
Cu–I
2.5441(4)
2.2269(7)
2.2321(7)
1.712(7)
1.708(2)
1.306(3)
1.306(3)
1.346(3)
1.352(3)
N(2A)–N(3A)
N(2B)–N(3B)
N(3A)–C(2A)
N(3B)–C(2B)
C(2A)–C(3A)
C(2A)–C(9A)
C(2B)–C(3B)
C(2B)–C(9B)
1.378(3)
1.378(3)
1.288(3)
1.289(3)
1.479(3)
1.493(3)
1.480(3)
1.493(3)
Cu–S(1A)
Cu–S(1B)
S(1A)–C(1A)
S(1B)–C(1B)
N(1A)–C(1A)
N(1B)–C(1B)
N(2A)–C(1A)
N(2B)–C(1B)
Bond angles
Hbztsc
C(1)–N(2)–N(3)
C(2)– N(3)–N(2)
N(1)–C(1)–S
119.71(13)
117.42(14)
124.71(13)
N(2)–C(1)–S
N(3)–C(2)–C(3)
N(3)–C(2)–C(9)
118.58(12)
124.33(14)
116.68(14)
1
P(2)–Cu–P(1)
P(2)–Cu–S
P(1)–Cu–S
P(2)–Cu–Cl
P(1)–Cu–Cl
S–Cu–Cl
126.00(3)
106.49(3)
107.17(3)
102.55(3)
106.96(3)
106.21(3)
101.93(10)
C(1B)–P(1)–Cu
C(1C)–P(1)–Cu
C(1A)–P(1)–Cu
C(1F)–P(2)–Cu
C(1D)–P(2)–Cu
C(1E)–P(2)–Cu
115.40(9)
117.17(10)
112.85(10)
117.60(9)
113.17(9)
114.27(10)
C(1)–S–Cu
2
P(2)–Cu–P(1)
P(2)–Cu–S
P(1)–Cu–S
P(2)–Cu–Br
P(1)–Cu–Br
S–Cu–Br
131.56(4)
104.64(4)
103.34(4)
99.49(6)
105.27(6)
112.38(4)
108.19(12)
C(1B)–P(1)–Cu
C(1C)–P(1)–Cu
C(1A)–P(1)–Cu
C(1F)–P(2)–Cu
C(1D)–P(2)–Cu
C(1E)–P(2)–Cu
109.40(10)
120.06(11)
115.35(12)
116.31(11)
112.30(11)
117.45(11)
The 13C NMR spectra provide more convincing infor-
mation about the monodentate behaviour of Hbztsc moi-
ety in the complexes. The C1 carbon signal appears at d
176.9 ppm in 1 and at d 176.5 ppm in 2, which are upfield
relative to the free ligand (d 178.8 ppm). Further, C2
carbon signal at d 157.9 ppm in 1 and d 151.7 ppm in 2
shifts downfield relative to the free ligand (d 150.98 ppm),
the former carbon showing more pronounced shift. This
behaviour is similar to that observed for related complexes
C(1)–S–Cu
3
S(1A)–Cu–S(1B)
S(1A)–Cu–I
S(1B)–Cu–I
C(1A)–S(1A)–Cu
C(1B)–S(1B)–Cu
119.62(3)
121.42(2)
118.95(2)
110.62(8)
110.30(9)
C(1A)–N(2A)–N(3A)
C(2A)–N(3A)–N(2A)
C(1B)–N(2B)–N(3B)
C(2B)–N(3B)–N(2B)
N(1A)–C(1A)–(N2A)
118.8(2)
117.6(2)
118.0(2)
117.6(2)
117.6(2)

2762
T.S. Lobana et al. / Polyhedron 25 (2006) 2755–2763
Table 3
˚
Hydrogen bonds (A) for complexes 1–3
Complex no.
D–H. . .A
d(D–H)
d(H. . .A)
d(D. . .A)
\(DHA)
1
N(1)–H(1A). . .Cl#1
N(1)–H(1B). . .Cl
0.88
0.88
2.44
2.54
3.230(2)
3.281(3)
149.3
142.7
2
3
N(1)–H(1A). . .Br#1
N(1)–H(1B). . .Br
0.88
0.88
2.63
2.64
3.407(4)
3.494(4)
147.3
163.1
N(1A)–(H1AA). . .I#1
N(1A)–H(1AB). . .I
N(1B)–H(1BA). . .I#2
N(1B)–H(1BB). . .N(1A)#2
N(1B)–H(1BB). . .I
0.88
0.88
0.88
0.88
0.88
3.08
2.65
3.19
2.67
2.75
3.570(2)
3.503(2)
3.764(2)
3.157(3)
3.509(2)
117.2
164.0
125.2
116.2
145.7
Table 4
Comparison of bond angles (°) of complexes 1–3 with related complexes
S. no.
Ligand
Complexes
C(1)–S–Cu
P–Cu–P
S–Cu–X
Hydrogen bonding (Hꢁ ꢁ ꢁX)
S
1
1
2
R
2
C
NH
3
1
N
C
2
N
R
H
H
I
R1, R2
Py, H
1
Cl (4)
Br (5)
I (6)
103.13(8)
105.82(15)
115.85(18)
120.92(2)
122.39(5)
117.21(5)
103.13(8)
107.76(4)
113.41(4)
–NH–
–NH–
–NH2–
2
3
4
Ph, H
Br (7)
I (8)
110.52(8)
115.73(7)
123.31(2)
118.11(2)
109.93(18)
115.42(2)
–NH2–
–NH–
p-OHC6H5, H
Br (9)
I (10)
107.0(11)
112.1(4)
135.4(1)
123.1(1)
114.81(9)
110.18(9)
–NH–
–NH–
Ph, Ph
Cl (1)
Br (2)
I (3)
101.93(10)
108.19(12)
110.62(8), 110.30(9)
126.00(3)
131.56(4)
108.22(17)
112.38(4)
121.42(2), 118.95(2)
–NH2–
–NH2–
–NH2–
5
Br (11)
I (12)
113.30(12)
115.50(2)
121.97(3)
124.09(5)
109.22(3)
112.13(4)
–NH2–
–NH2–
N
4
2
3
5
9
O
4
6
8
N
7
H
(1)–(3) this work; [CuCl(Hpytsc)(PPh3)2] (4) [CuBr(Hpytsc)(PPh3)2] (5) [CuI(Hpytsc)(PPh3)2] (6) (Hpytsc = pyridine-2-carbaldehyde thiosemicarbazone),
[CuBr(Hbtsc)(PPh3)2] (7), [CuI(Hbtsc)(PPh3)2]. (8) (Hbtsc = Benzaldehyde thiosemicarbazone) [24a]; [CuBr(L)(PPh3)2] (9), [CuI(L)(PPh3)2] (10) (L = 4
hydroxybenzaldehyde thiosemicarbazone) [21]; [CuBr(H2istsc)(PPh3)2] (11); [CuI(H2istsc)(PPh3)2] (12) (H2istsc = Isatin-3-carbaldehyde thiosemicarba-
zone) [19].
[24a]. C3 carbon in free ligand shows a pair of low intensity
signals at d 136.3 ppm and d 131.0 ppm. This can be attrib-
uted to the fact that the two phenyl rings at C2 carbon in
the free ligand as well as in complexes are not coplanar
rather at an angle with respect to each other. Thus carbon
atoms of two phenyl rings at C2 carbon are in different
chemical environments due to different spatial arrangement
of phenyl rings, also revealed by the X-ray structure of the
ligand (Fig. 1a). Similarly, C4,8 and C6 carbon atoms show
pairs of signals at d 129.8, 127.7 ppm and d 130.3,
130.2 ppm, respectively. A single broad signal at d
128.4 ppm is observed for C5,7 carbons. Similar signals
are observed for ligand ring carbons (C3,C4,8,C5,7,C6) in
the complexes 1 and 2 showing no significant shift. Various
signals due to ipso carbon, ortho, meta and para carbons of
phosphine ligands are well resolved in both the complexes.
The i-C, ortho, meta and para carbon signals of Ph rings of
Cu
Cu
X
X
S
H
S
H
C
N1
C
N2
N2
H
N1
H
H
4-6, 8-10
1-3, 7, 11, 12
H
Chart 3.

T.S. Lobana et al. / Polyhedron 25 (2006) 2755–2763
2763
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PPh3 in 1 appear as separate and are similar to the corre-
sponding signals in 2.
The 31P NMR signal of free Ph3P appears at
ꢀ113.153 ppm. A single broad signal is observed in the
complexes 1 and 2 indicating the equivalence of two
PPh3 groups. This signal shifted downfield to
ꢀ112.16 ppm in 1 and ꢀ112.73 ppm in 2 with coordina-
tion shifts (dcomplex ꢀ dligand) of 0.99 and 0.43 ppm, respec-
tively. Such low coordination shifts can be attributed to
the equilibrium between coordinated PPh3 and the free
PPh3 in the solution phase, and similar behaviour was
observed in the literature [24b].
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4. Supplementary material
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4023.
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Supplementary data is available from CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: +44 12336033;
e-mail: deposit@ccdc.cam.ac.uk, or on the web www.ccdc.
cam.ac.uk) on request quoting the deposition number
CCDC 297906 for (1), 297907 for (2), 297908 for (3) and
297909 for Hbztsc.
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Acknowledgements
Financial assistance from CSIR, New Delhi (F. No. 9/
254(159)/2005-EMR-I) and research facilities to one of us
(Sonia) by the university are gratefully acknowledged.
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