Metal derivatives of thiosemicarbazones: Crystal and molecular structures of mono- and dinuclear copper(II) complexes with N1-subsitituted salicylaldehyde thiosemicarbazones

Article abstract of DOI:10.1002/zaac.201200180

Reactions of copper(II) acetate with N¹-subsitituted salicylaldehyde thiosemicarbazones [R¹R²C ²=N³-N²H-C¹(=S)-N¹HR ³;R¹ = 2-HO-C₆H₄-, R² = H: R³ = Me (H₂L¹), Et (H₂L ²)] are described. Copper(II) acetate was reacted with H ₂L¹ and H₂L² ligands in the presence of polypyridyl co-ligands, and this led to the formation ofmononuclear complexes, [Cu(κ³-O, N, S-L¹)(κ²-N, N-bipy)] (1),[Cu(κ³-O, N, S-L)(κ²-N, N-phen)] [L = L¹ (3), L² (4)], [Cu(κ³-O, N, S-L)(κ²-N, N-tmphen)] [L =L¹ (5), L² (6)] and a dinuclear complex, [Cu₂L²₂(bipy)] (2) (bipy = 2, 2′-bipyridine, phen = 1, 10-phenanthroline, tmphen = 3, 4, 7, 8-tetramethyl-1, 10-phenanthroline). In dinuclear complex 2, one ligand is O, N³,S-chelating, while second is O, N³,S-chelation-cum- N²-bridging; and in all others thio-ligands are O, N ³,S-chelating. The μ_eff values for the complexes lie in the range of 1.79-1.83 BM. Complexes 1, 3-6 have square pyramidal arrangement, whereas complex 2 has two independent molecules in the crystal lattice, and each molecule has trigonal bipyramidal square planar (5:4) coordination pair. Complexes 2, 4, and 6 showed fluorescence properties. Copyright

Full text of DOI:10.1002/zaac.201200180

Job/Unit: Z12180
/KAP1
Date: 07-08-12 16:59:58
Pages: 8
ARTICLE
DOI: 10.1002/zaac.201200180
Metal Derivatives of Thiosemicarbazones: Crystal and Molecular Structures
of Mono- and Dinuclear Copper(II) Complexes with N1-Subsitituted
Salicylaldehyde Thiosemicarbazones
Tarlok S. Lobana,*[a] Poonam Kumari,[a] Ray J. Butcher,[b] Jerry P. Jasinski,[c] and
James A. Golen[c]
Keywords: Thiosemicarbazone; Copper; Bipyridine; Phenanthroline
Abstract. Reactions of copper(II) acetate with N1-subsitituted salicyl-
aldehyde thiosemicarbazones [R1R2C2=N3–N2H–C1(=S)–N1HR3;
throline, tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline). In dinu-
clear complex 2, one ligand is O,N3,S-chelating, while second is
R1 = 2-HO–C6H4–, R2 = H : R3 = Me (H2L1), Et (H2L2)] are described. O,N3,S-chelation-cum-N2-bridging; and in all others thio-ligands are
Copper(II) acetate was reacted with H2L1 and H2L2 ligands in the pres-
ence of polypyridyl co-ligands, and this led to the formation of
O,N3,S-chelating. The μeff values for the complexes lie in the range of
1.79–1.83 BM. Complexes 1, 3–6 have square pyramidal arrangement,
mononuclear complexes, [Cu(κ3-O,N,S-L1)(κ2-N,N-bipy)] (1), whereas complex 2 has two independent molecules in the crystal lat-
[Cu(κ3-O,N,S-L)(κ2-N,N-phen)] [L = L1 (3), L2 (4)], [Cu(κ3-O,N,S- tice, and each molecule has trigonal bipyramidal square planar (5:4)
L)(κ2-N,N-tmphen)] [L =L1 (5), L2 (6)] and a dinuclear complex, coordination pair. Complexes 2, 4, and 6 showed fluorescence proper-
[Cu2L2 (bipy)] (2) (bipy = 2,2Ј-bipyridine, phen = 1,10-phenan-
ties.
2
base adducts containing thiosemicarbazones have not been
much investigated.[1] For instance, for copper(II) there are lim-
ited reports on complexes of salicylaldehyde based thiosemi-
carbazonates (H2L) in the presence of polypyridyl N,N donors,
namely, [Cu(κ3-O,N,S-L)(κ2-N,N-D)] (L = salicylaldehyde
thiosemicarbazonate; D = bipy, phen), [Cu(κ3-O,N,S-L)(κ2-
N,N-D)] (L = salicylaldehyde-N1-phenyl thiosemicarbazonate;
D = bipy, phen), [Cu(κ3-O,N,S-L)(κ2-N,N-D)] (L = 3,5-di-tbu-
2-hydroxybenzaldehyde-N1-phenyl-thiosemicarbazonate; D =
bipy, phen, dmp), and [Cu(κ3-O,N,S-L)(κ2-N,N-D)] (L =
2-hydroxy-acetophenone-N1-methylphenyl thiosemicarbazone;
D = bipy) (bipy = 2,2Ј-bipyridine, phen = 1,10-phenanthroline,
dmp = 2,9-dimethyl-1,10-phenanthroline).[22] All these com-
plexes have square pyramidal arrangement.
Herein in this paper, copper(II) complexes with salicylalde-
hyde-N1-methyl (or ethyl) thiosemicarbazones in the presence
of N,N donor co-ligands (Scheme 1) are described and com-
pared with its –N1HPh analogue. It was anticipated that the
presence of electron releasing groups (R3 = Me, Et) at N1 atom
in presence of polypyridyl co-ligands with π electron net
works might alter chemical/optical properties such as bonding
and fluorescence of the resulting complexes vis-à-vis those of
the complexes having phenyl group at N1(–N1HPh)
Introduction
Thiosemicarbazones
[R1R2C2=N3–N2H–C1(=S)–N1HR3]
represent an interesting class of N, S donor ligands due to their
variable donor ability and structural diversity.[1–6] Salicylalde-
hyde thiosemicarbazones with O, N, S donor atoms have been
of considerable interest due to their remarkable structural and
biological properties.[7–12] Interactions between aromatic rings
of salicylaldehyde thio ligands are very important in proteins
and protein-DNA systems for protein stabilization and various
regulatory processes.[13–16] A number of thiosemicarbazones
and their copper complexes have been found to be active in
cell destruction, as well as in the inhibition of DNA synthe-
sis.[17–19] The copper(II) metal ion is especially attractive for
study because of its rich spectroscopic and magnetic properties
that often change during the course of enzyme catalysis.
There has been considerable interest in the compounds con-
taining N,N donor co-ligands such as bipyridine and phenan-
throline because of their versatile self-assembling properties
and tendency to act as building blocks in the design of metal-
ligand networks.[20,21] However, transition metal polypyridyl
* Prof. Dr. T. S. Lobana
E-Mail: tarlokslobana@yahoo.co.in
[a] Department of Chemistry
Guru Nanak Dev University
Amritsar-143 005, India
[b] Department of Chemistry
Howard University
Washington DC 20059, USA
[c] Department of Chemistry
Keene State College
229 Main Street
Keene, NH 03435–2001, USA
Scheme 1.
Z. Anorg. Allg. Chem. 0000, ᭿,(᭿), 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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T. S. Lobana et al.
ARTICLE
376 (0.70ϫ104), 323 (1.00ϫ104), 313 (0.95ϫ104), 280 (1.52ϫ104),
264 (2.05ϫ104). Complex 4 was prepared by a similar method.
Experimental Section
Materials and Techniques: Copper(II) acetate monohydrate
Cu(OAc)2·H2O, N-methyl thiosemicarbazide, N-ethyl thiosemicarbaz-
[Cu(κ3-O,N,S-L2)(κ2-N,N-phen)]·2H2O (4): Color: red (61%, M.p.
ide, salicylaldehyde, 2,2Ј-bipyridine (bipy), 1,10-phenanthroline 220–222 °C). μeff = 1.83 BM. C22H23CuN5OS: calcd. C 52.75; H 4.60;
(phen) and 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen) were N 13.98%; found: C 53.01; H 4.54; N 14.02%. IR (KBr, selected
procured from Aldrich Sigma Ltd. The thio ligands were synthesized absorption bands): ν(N–H) 3425 br; ν(C–H) 2989 w, 2929 m, 2855 w;
by conventional procedures.[23,24] C, H, and N were carried out with ν(C=N) + ν(C=C) 1597 s, 1518 s; ν(C–N) 1073 s, 1045 s, 914 w;
a thermoelectron FLASHEA1112 analyzer. The melting points were ν(C–S) 759 s cm–1. Electronic absorption spectrum (10–3/10–4 m in
determined with a Gallenkamp electrically heated apparatus. Magnetic DMSO, λmax /nm,
ε
/L·mol–1·cm–1): 580 (0.15ϫ103), 507
susceptibility was recorded with a magnetic susceptibility balance pro-
(0.25ϫ103), 396 (0.94ϫ104), 375 (0.84ϫ104), 326 (1.26ϫ104), 312
cured from Johnson Matthey, Catalytic Systems Division Equipment, (1.19ϫ104), 264 (2.96ϫ104). Fluorescence spectrum: λmax
=
ex
em
UK. The IR spectra were recorded using KBr pellets with a Varian 320 nm, λmax = 386 nm.
666–IR FT-IR spectrometer. The UV/visible spectra were recorded
[Cu(κ3-O,N,S-L1)(κ2-N,N-tmphen)]·0.11(C6H24O6)·2(H2O) (5): To a
suspension of {CuL1} (0.010 g, 0.037 mmol) in acetonitrile was added
tmphen (0.008 g, 0.037 mmol), and the contents were stirred for 1 h.
A clear red solution obtained was allowed to evaporate at room tem-
perature, which yielded red compound. This compound was crys-
tallized from a mixture of dichloromethane and methanol (3:1, v:v).
with a UV-1601PC Shimadzu spectrophotometer. Fluorescence spectra
of complexes were recorded with a Varian Cary Eclipse Fluorescence
spectrophotometer.
Synthesis of Complexes
Color: red (73%, M.p. 212–214 °C). μeff
=
1.80 BM.
[Cu(κ3-O,N,S-L1)(κ2-N,N-bipy)]·H2O (1): To a solution of H2L1
(0.026 g, 0.125 mmol) in methanol was added solid Cu(OAc)2H2O
(0.025 g, 0.125 mmol) and the contents were stirred. The brown pre-
cipitates formed during stirring were filtered and allowed to dry at
room temperature. The analytical data supported the formation of a
compound of empirical composition, {CuL1} (anal. calcd. for
C9H9CuN3OS: C 39.92; H 3.33; N 15.52%; found: C 40.09; H 3.27;
N 15.71%). To a suspension of {CuL1} (0.010 g, 0.037 mmol) in ace-
tonitrile was added solid bipyridine (0.007 g, 0.037 mmol), and the
contents were stirred for 1 h. A clear reddish green solution obtained
was allowed to evaporate at room temperature, which yielded red-
green needles. Color: green (66%, M.p. 198–200 °C). μeff = 1.79 BM.
C21H17CuN5OS: calcd. C 56.63; H 3.82; N 15.73%; found: C 56.46;
H 4.01; N 15.62%. IR (KBr, selected absorption bands): ν(N1–H)
3436 br; ν(C–H) 3056 w, 2957 m, 2924 w, 2891 m; ν(C=N) + ν(C=C)
1534 s, 1489 s; ν(C–N) 1032 s, 971 w; ν(C–S) 762 s cm–1. Electronic
absorption spectrum (10–3/10–4 m in DMSO, λmax /nm, ε /L·mol–1·cm–1):
576 (0.264ϫ103), 391 (1.46ϫ104), 377 (1.38ϫ104), 354
(1.07ϫ104), 325 (1.91ϫ104), 316 (1.82ϫ104), 275 (1.47ϫ104).
Complex 2 was prepared by a similar method.
C25.66H31.64CuN5O3.66S: calcd. C 54.57; H 5.61; N 12.40%; found: C
54.46; H 5.64; N 12.26%. IR (KBr, selected absorption bands):
ν(N–H) 3392 s, ν(C–H) 3012 m, 2950 w, 2920 m, 2850 w; ν(C=N) +
ν(C=C) 1618 s, 1586 s, ν(C–N) 1078 s, 1027 s, 953 s, ν(C–S) 767 s
cm–1. Electronic absorption spectrum (10–3/10–4
m in DMSO,
λmax /nm, ε /L·mol–1·cm–1): 574 (0.19ϫ103), 394 (1.14ϫ104), 378
(1.06ϫ104), 324 (1.46ϫ104), 310 (1.50ϫ104), 274 (2.95ϫ104).
Complex 6 was prepared by a similar method.
[Cu(κ3-O,N,S-L2)(κ2-N,N-tmphen)] (6): Color: red (69%, M.p. 235–
237 °C). μeff = 1.82 BM. C26H27CuN5OS: calcd. C 59.73; H 5.17; N
13.40%; found: C 60.01; H 5.47; N 13.09%. IR (KBr, selected absorp-
tion bands): ν(N–H) 3446 br; ν(C–H) 2997 m, 2958 w, 2924 m, 2854
w; ν(C=N) + ν(C=C) 1599 s, 1488 s; ν(C–N) 1068 s, 1016 s, 917 s;
ν(C–S) 767 s cm–1. Electronic absorption spectrum (10–3/10–4 m in
DMSO, λmax /nm,
ε
/L·mol–1·cm–1): 579 (0.11ϫ104), 505
(0.24ϫ104), 389 (0.985ϫ104), 324 (1.31ϫ104), 309 (1.57ϫ104),
ex
273 (3.84ϫ104), 270 (3.72ϫ104). Fluorescence spectrum: λmax
=
em
320 nm, λmax = 394 nm.
X-ray Crystallography
[Cu2L2 (bipy)] (2): Color: black (66%, M.p. 245–247 °C). μeff = 1.81
2
BM. C30H30Cu2N8O2S2: calcd. C 49.60; H 4.13; N 15.43%; found: C
50.06; H 4.22; N 15.49%. IR (KBr, selected absorption bands):
ν(N1–H) 3439 br; ν(C–H) 3056 m, 2977 m, 2925 m, 2854 m; ν(C=N)
+ ν(C=C) 1545 s, 1475 s; ν(C–N) 1053 m, 928 w; ν(C–S) 751 s cm–1.
Electronic absorption spectrum (10–3/10–4 m in MeOH, λmax /nm, ε /
L·mol–1·cm–1): 572 (0.21ϫ103), 392 (1.06ϫ104), 377 (0.99ϫ104),
325 (1.34ϫ104), 316 (1.29ϫ104), 279 (1.64ϫ104). Fluorescence
A single crystal was mounted on a glass fiber and used for data collec-
tion with a Xcalibur, Ruby, Gemini (1), Xcalibur, Eos, Gemini (2, 6),
and a Bruker AXS SMART APEX CCD (5) diffractometer, equipped
with graphite monochromated Mo-Kα (λ = 0.71073 Å). Crystal data
were collected at 123(2) (1), 170(2) (2, 6) and 100(2) (5) K. For com-
plexes 1, 2 and 6, data were processed with CrysAlisPro CCD (data
collection), CrysAlisPro RED (cell refinement, data reduction).[25] The
structure was solved by direct methods using the program SHELXS-
97, refined by full-matrix least-squares techniques against F2 using
SHELXL-97 and molecular graphics from SHELXTL.[26] For complex
5, data were processed with SMART 5.630 and corrected for absorp-
tion using SADABS.[27] The structures were solved by direct methods
and refined by full-matrix least-squares method based on F2 using the
program using SHELXTL 6.14.[28] Atomic scattering factors from “In-
ternational Tables for Crystallography”.[29] The crystallographic data
and important bond parameters of complexes 1, 2, 5, and 6 are given
in Table 1 and Table 2, respectively.
ex
em
spectrum: λmax = 320 nm, λmax = 442 nm.
[Cu(κ3-O,N,S-L1)(κ2-N,N-phen)]·H2O (3): To
a
suspension of
{CuL1} (0.010 g, 0.037 mmol) in acetonitrile was added phen (0.007 g,
0.037 mmol) and the contents were stirred for 1 h. The clear reddish
green solution obtained was allowed to evaporate at room temperature,
which yielded green needles. Color: green (66%, M.p. 205–207 °C).
μeff = 1.80 BM. C21H19CuN5O2S: calcd. C 53.79; H 4.06; N 14.94%;
found: C 53.96; H 4.21; N 15.15%. IR (KBr, selected absorption
bands): ν(N1–H) 3413 br; ν(C–H) 3042 m, 2922 m, 2853 m, ν(C=N)
+ ν(C=C) 1597 s, 1493 s, ν(C–N) 1028 m, 913 w; ν(C–S) 765 s cm–1.
Electronic absorption spectrum (10–3/10–4 m in DMSO, λmax /nm, Crystallographic data (excluding structure factors) for the structures in
ε /L·mol–1·cm–1): 579 (0.15ϫ103), 508 (0.23ϫ103), 394 (0.77ϫ104),
this paper have been deposited with the Cambridge Crystallographic
2
www.zaac.wiley-vch.de
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 0000, 0–0

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Copper(II) Complexes with N1-Subsitituted Salicylaldehyde Thiosemicarbazones
Table 1. Crystallographic data for compounds 1, 2, 5, and 6.
1
2
5
6
Empirical formula
M
C19H19CuN5O2S
444.99
C30H30Cu2N8O2S2
725.82
C25.66H31.64Cu N5 O3.66
564.30
S
C26H27CuN5OS
521.13
T /K
123(2)
170(2)
100(2)
170(2)
Crystal system
Space group
orthorhombic
Pna21
triclinic
P1
rhombohedral
R3
monoclinic
P21/c
¯
¯
Flack parameters
0.016(11)
–
–
–
Unit cell dimensions
a /Å
b /Å
c /Å
α /°
17.714(5)
6.586(2)
17.008(6)
90.00
90.00
90.00
1984.3(1)
4
1.490
14.304(4)
14.898(4)
16.589(3)
113.04(2)
90.36(16)
95.96(2)
3231.4(1)
4
22.196(2)
22.196(2)
26.598(4)
90.00
12.007(3)
11.715(3)
17.412(5)
90.00
93.24(2)
90.00
2445.2(1)
4
1.416
β /°
90.00
γ /°
120.00
11348.2(2)
18
V /Å3
Z
Dcalcd. /g·cm–3
1.492
1.486
μ /mm–1
1.231
1.487
0.990
1.007
F(000)
916
1488
0.23ϫ0.20ϫ0.15
29350
15393 [R(int) =
0.0652]
5307.8
0.43ϫ0.39ϫ0.13
33520
1084
0.30ϫ0.20ϫ0.10
15621
Crystal size /mm3
Reflections collected
Unique reflections
0.35ϫ0.28ϫ0.14
20332
7931 [R(int) = 0.0336]
6274 [R(int) = 0.0789]
5722 [R(int) = 0.0306]
Data/ restraints / param-
eters
7931 / 4 / 259
15393 / 817 / 14
6274 / 16 / 357
5722 / 1 / 325
Index ranges
–19 Յ h Յ 29
–8 Յ k Յ 10
–23 Յ l Յ 28
–18 Յ h Յ 18
–19 Յ k Յ 19
–21 Յ l Յ 21
R1 = 0.0812,
wR2 = 0. 1926
R1 = 0.1462,
–29 Յ h Յ 29
–29 Յ k Յ 29
–35 Յ l Յ 35
R1 = 0.0629,
wR2 = 0.1600
R1 = 0.0914,
–13 Յ h Յ 15
–15 Յ k Յ 15
–21 Յ l Յ 22
R1 = 0.0459,
wR2 = 0.1107
R1 = 0.0683,
Final R indices[I Ͼ 2σ(I)] R1 = 0.0499,
wR2 = 0.1060
R indices (all data)
R1 = 0.0593,
wR2 = 0.1094
1.338 and –1.160
wR2 = 0.2360
1.515 and –1.221
wR2 = 0.1800
1.473 and –0.728
wR2 = 0.1238
0.500 and –0.316
Largest diff. peak and
hole /e·Å–3
shown the disappearance of ν(N2–H) and ν(O–H) bands,
which reveals that thio ligands are coordinated to the metal
atom as anions. The diagnostic ν(C–S) bands lie in the range
of 751–767 cm–1. Other characteristic bands are given in the
Experimental Section. Magnetic moments of complexes
[μeff = 1.79 (1), 1.81 (2), 1.80 (3, 5), 1.83 (4), 1.82 (6) BM]
are close to the spin-only value of 1.73 BM for d9 CuII com-
plexes.[30] Scheme 2 shows a coordination pattern of com-
plexes, confirmed by X-ray crystallography (vide infra).
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK.
Copies of the data can be obtained free of charge on quoting the de-
pository numbers CCDC-848767 (1), -848768 (2), -875852 (5),
-875853 (6) (Fax: +44-1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk,
http://www.ccdc.cam.ac.uk).
Results and Discussion
Synthesis and IR Spectroscopy
The addition of a solid Cu(OAc)2·H2O to a solution of sali-
cylaldehyde-N1-methyl thiosemicarbazone ligand (H2L1) in
methanol in 1:1 molar ratio (M:L) formed a rust colored com-
pound of empirical composition, {CuL1}. Due to its low solu-
Crystal Structures
The crystal structure of complex [CuL1(bipy)] (1) shows
bility, it could not be crystallized to ascertain its structure, and that copper is coordinated by phenolato oxygen (O1A), azome-
this product could be an oligomer or a polymer (by O or S thine nitrogen (N1A), thiolato sulfur (S), and bipyridine nitro-
donor atoms). The reactions of {CuL1} with bipyridine in ace- gen atoms, N(1B) and N(2B) (Figure 1). Herein, O1A, N1A,
tonitrile in 1:1 or 2:1 molar ratios (M:bipy) formed the product, S, and N2B atoms form an equatorial plane and the N1B atom
[Cu(κ3-O,N,S-L1)(κ2-N,N-bipy)] (1). The reactions of of bipy occupies the axial position. Trans angles in equatorial
Cu(OAc)2 with H2L2 in presence of bipyridine in 1:1 or 2:1 plane N(1A)–Cu–N(2B) and S–Cu–O1A [175.88(8),
molar ratios (M:bipy) rather has formed a dinuclear complex, 157.95(5)°] are different and close to those reported in litera-
[Cu2L2 (bipy)] (2). The reactions of H2L1 and H2L2 using phen ture [177.94(2), 156.71(1)°],[23] suggesting a distorted square
2
and tmphen as co-ligands in acetonitrile also yielded mononu- pyramidal arrangement around the central copper atom. The
clear complexes, [Cu(κ3-O,N,S-L)(κ2-N,N-phen)] [L = L1 (3), copper to thio ligand bond lengths, Cu–N(1A) 1.953(2),
L2 (4)] and [Cu(κ3-O,N,S-L)((κ2-N,N-tmphen)] [L = L1 (5), Cu–O(1A) 1.954(2), and Cu–S 2.276(7) Å, are similar to those
L2 (6)]. The IR spectroscopic data of complexes 1–6 have reported in literature.[23] Copper to bipyridine distances,
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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T. S. Lobana et al.
ARTICLE
Table 2. Bonding parameters of compounds 1, 2, 5, and 6.
1
Cu–N(1A)
Cu–N(1B)
Cu–S
N(1A)–Cu–O(1A) 93.70(7)
N(1A)–Cu–N(1B) 99.97(7)
N(2B)–Cu–N(1B) 76.75(7)
1.953(2)
2.246(2)
2.276(7)
Cu–N(2B)
Cu–O(1A)
S–C(8A)
O(1A)–Cu–N(2B)
O(1A)–Cu–N(1B)
N(1A)–Cu–S
N(1B)–Cu–S
O(1A)–Cu–S
2.018(2)
1.954(2)
1.752(2)
89.31(7)
99.12(7)
85.26(6)
102.76(6)
157.95(5)
N(2B)–Cu–S
N(1A)–Cu–N(2B) 175.88(8)
93.01(6)
2
Cu(1)–O(1)
Cu(1)–N(2)
Cu(1)–S(1)
Cu(2)–N(6)
Cu(2)–S(2)
Cu(3)–O(3)
Cu(3)–N(9)
Cu(4)–O(4)
Cu(4)–N(12)
S(1)–C(18)
S(3)–C(48)
O(1)–Cu(1)–N(3) 91.89(2)
O(1)–Cu(1)–N(1) 94.70(2)
N(2)–Cu(1)–N(1) 76.60(2)
N(3)–Cu(1)–S(1) 85.26(2)
N(1)–Cu(1)–S(1) 122.22(2)
O(2)–Cu(2)–N(4) 88.8(2)
N(4)–Cu(2)–S(2) 92.93(2)
O(3)–Cu(3)–N(10) 94.20(2)
O(3)–Cu(3)–N(9) 95.00(2)
N(11)–Cu(3)–S(3) 85.78(2)
N(10)–Cu(3)–S(3) 92.03(2)
O(4)–Cu(4)–N(14) 93.40(3)
N(14)–Cu(4)–S(4) 85.50(2)
N(3)–Cu(1)–N(2) 172.90(2)
O(2)–Cu(2)–S(2) 178.03(2)
1.967(4)
2.024(5)
2.265(2)
1.961(5)
2.252(2)
1.971(5)
2.222(6)
1.930(6)
2.038(7)
1.737(7)
1.702(9)
Cu(1)–N(3)
Cu(1)–N(1)
Cu(2)–O(2)
Cu(2)–N(4)
Cu(3)–N(11)
Cu(3)–N(10)
Cu(3)–S(3)
Cu(4)–N(14)
Cu(4)–S(4)
1.987(5)
2.238(5)
1.924(5)
2.056(5)
1.969(6)
2.022(6)
2.256(2)
1.955(8)
2.253(2)
1.757(7)
1.755(8)
94.64(2)
100.00(2)
142.92(2)
91.24(2)
92.70(2)
85.68(2)
Scheme 2.
S(2)–C(28)
S(4)–C(58)
O(1)–Cu(1)–N(2)
N(3)–Cu(1)–N(1)
O(1)–Cu(1)–S(1)
N(2)–Cu(1)–S(1)
O(2)–Cu(2)–N(6)
N(6)–Cu(2)–S(2)
N(11)–Cu(3)–O(3) 91.20(2)
N(11)–Cu(3)–N(9) 98.90(2)
N(10)–Cu(3)–N(9) 77.10(2)
O(3)–Cu(3)–S(3)
N(9)–Cu(3)–S(3)
O(4)–Cu(4)–N(12) 87.80(3)
N(12)–Cu(4)–S(4)
N(6)–Cu(2)–N(4)
N(11)–Cu(3)–N(10) 173.50(2)
142.86(2)
122.10(2)
93.29(2)
174.70(2)
N(14)–Cu(4)–
N(12)
177.80(3)
O(4)–Cu(4)–S(4)
178.50(2)
5
Cu–N(1)
Cu–N(5)
Cu–S(2)
C(7)–N(1)
N(1)–Cu–O(1)
O(1)–Cu–N(5)
N(4)–Cu–N(5)
N(5)–Cu–S(2)
N(1)–Cu–N(5)
1.967(3)
2.037(3)
2.299(1)
1.285(5)
93.74(1)
87.62(1)
78.16(1)
92.83(8)
177.58(1)
Cu–N(4)
Cu–O(1)
C(8)–S(2)
2.223(3)
1.958(3)
1.745(4)
Figure 1. Molecular structure of complex [CuL1(bipy)]·H2O (1).
N(4)–Cu–O(1)
N(1)–Cu–N(4)
N(1)–Cu–S(2)
O(1)–Cu–S(2)
94.39(1)
103.71(1)
85.25(9)
161.75(8)
In complex [Cu2L2 (bipy)] (2), copper(II) has adopted two
2
different coordination environments. Cu1 is coordinated by O,
N
azomethine, S atoms of one thio ligand and N,N atoms of bipyr-
6
idine co-ligand, whereas the central Cu2 atom is coordinated
by O, Nazomethine, S donor atoms of the second thio ligand. The
fourth coordination site of Cu2 is occupied by Nhydrazinic atom
from the thio ligand bonded to the central Cu1 atom and
formed a dinuclear complex with 5:4 coordination pattern (Fig-
ure 2). This complex has two independent molecules in the
crystal lattice, with slightly different bond parameters. Herein,
N(1), O(1), S(1) atoms form an equatorial plane with bond
angles, O1–Cu1–N1 94.70(2), N1–Cu1–S1 122.22(2), and
Cu(1)–O(1)
Cu(1)–N(5)
Cu(1)–N(4)
O(1)–Cu(1)–N(1) 94.07(8)
N(1)–Cu(1)–S(1) 85.04(6)
O(1)–Cu(1)–N(4) 95.87(9)
N(5)–Cu(1)–N(4) 76.54(8)
N(1)–Cu(1)–N(5) 176.88(9)
1.922(2)
2.029(2)
2.323(2)
Cu(1)–N(1)
Cu(1)–S(1)
S(1)–C(8)
O(1)–Cu(1)–N(5)
N(5)–Cu(1)–S(1)
N(1)–Cu(1)–N(4)
S(1)–Cu(1)–N(4)
O(1)–Cu(1)–S(1)
1.952(2)
2.280(8)
1.746(3)
88.29(8)
92.10(6)
105.20(8)
101.10(6)
162.64(8)
Cu–N(1B) 2.246(2) and Cu–N(2B) 2.018(2) Å are different S1–Cu1–O1 142.92(2)° (total sum = 359.84°), whereas N(2),
and longer than copper to azomethine nitrogen bond length N(3) atoms occupy the axial sides with an N2–Cu1–N3 bond
[1.953(2) Å], which suggest that the central copper atom is angle of 172.9(2)°. Thus the environment around Cu1 is dis-
displaced above the O(1A), S, N(1A), and N(2B) equatorial torted trigonal bipyramidal. The bond angles around Cu2,
plane and towards the elongated apical N(1B) atom.
N(6)–Cu(2)–N(4) 174.70(2) and O(2)–Cu(2)–S(2) 178.03(2)°,
4
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Copper(II) Complexes with N1-Subsitituted Salicylaldehyde Thiosemicarbazones
suggest a distorted square-planar arrangement. Copper to thio
ligand bond lengths are Cu(1)–O(1) 1.967(4), Cu(1)–N(3)
1.987(5), Cu(1)–S(1) 2.265(2), Cu(2)–O(2) 1.924(5), Cu(2)–
N(6) 1.961(5), and Cu(2)–S(2) 2.252(2) Å. The Cu–Nhydrazinic
bond length, Cu(2)–N(4), is 2.056(5) Å, and is close to Cu–
N
azomethine. The bond length, Cu(1)–Nazomethine 1.987(5) Å, is
similar to that in 1 [1.953(2) Å]. Further, Cu···Cu separation
(4.812, 4.832 Å) is much longer than twice the sum of the van
der Waals radius of copper atoms, 2.80 Å.[30]
Figure 3.
Molecular
structure
of
complex
[CuL1(tmphen)]·0.11{(CH3OH)6}·2(H2O) (5). The disordered meth-
anol molecules are removed for clarity.
Figure 4. Molecular structure of complex [CuL2(tmphen)] (6).
Figure 2. Molecular structure of complex [Cu2(L2)2(bipy)] (2).
dal or square pyramidal arrangements (types B and C, Scheme
4).
Mononuclear
complexes,
[Cu(κ3-O,N,S-L1)(κ2-N,N-
tmphen)]·0.11(C6H24O6)·2(H2O) (5) and [Cu(κ3-O,N,S-L2)(κ2-
N,N-tmphen)] (6), have coordination pattern and bond param-
eters similar to those of complex 1. Compound 5 has distorted
methanol molecule in the crystal lattice. In these complexes
fourth and fifth coordination sites around the central metal
atom are occupied by nitrogen atoms of the tmphen co-ligand
(Figure 3 and Figure 4). Complexes 3 and 4 of phen co-ligand
did not crystallize and are believed to have structures similar
to1.
Scheme 3.
Analysis of Results
Salicylaldehyde-based thiosemicarbazones (H2L) exhibit
O,N,S chelation and bind to CuII as dianion, and form species
[Cu(κ3-O,N,S-L)], which with a monodentate ligand such as
py formed square-planar complexes (Scheme 3).[23] In the pre-
sented studies, it was believed that bidentate ligands such as
2,2Ј-bipyridine (bipy), 1,10-phenanthroline (phen) and 3,4,7,8-
tetramethyl-1,10-phenanthroline (tmphen) might form square-
planar complex with de-ligation of one of donor atoms (type
A) or form five coordinated complexes with trigonal bipyrami- Scheme 4.
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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T. S. Lobana et al.
ARTICLE
Figure 5. Inter- and intra-molecular interactions in 1, 2, 5, and 6.
The addition of N,N donor bipyridine to [Cu(κ3-O,N,S-L)] complex 6, only one ligand-to-metal charge-transfer band is
has formed complexes of different stoichiometries (Figure 5). present at 389 nm. Another d–d band (ν2) appears in the range
For R3 = Me in H2L1, a mononuclear square pyramidal com- 505–580 nm.
plex of stoichiometry, [CuL1(bipy)] (1) was obtained. How-
Fluorescence spectra of all complexes were recorded in
ever, the introduction of the ethyl group at N1 nitrogen (R3 = DMSO. Complexes 1, 3, and 5 did not exhibit fluorescence,
em
Et in H2L2 in place of Me) favored the formation of a N2- complex 2 exhibited a fluorescence band at λmax = 442 nm
ex
bridged dinuclear complex [Cu2L2(bipy)] (2) with 5:4 coordi- upon excitation at λmax = 340 nm (Figure 6). Complex 4
nation pair. In contrast, the interaction of [Cu(κ3-O,N,S-L)] [L showed two weak fluorescence bands at λmaxem = 362, 386 nm
ex
= L1 (R3 = Me), L2 (R3 = Et)] with tmphen formed only square (λmax = 320 nm) and complex 6 exhibited a weak band at
pyramidal complexes, [CuL1(tmphen)]·0.11(C6H24O6)·2(H2O) λmaxem = 394 nm (λmaxex = 320 nm). The origin of fluorescence
(5) and [CuL2(tmphen)] (6). The formation of mono- and dinu- is believed to be centered on bipy ligands, i.e. π–π transitions.
clear complexes might be due to the presence of different inter- The presence of ethyl group at N1 atom appears to induce fluo-
and intra-molecular interactions between two adjacent mole- rescence properties in complexes 2, 4, and 6, which could be
cules. In 1, water is present in the crystal lattice and this water attributed to the increase in donor ability of the thio ligands
molecule is engaged in strong hydrogen bonding with the N1H assisting the co-ligands in fluorescence by way of enhancing
and phenoxy groups of two adjacent molecules. However, in the life time of the excited state.
2, there is no solvent in the crystal lattice. Herein N1H hydro-
gen of thio ligand coordinated to Cu1 is engaged in hydrogen
bonding to the phenoxy group of the thio ligand coordinated
to Cu2 and favored the formation of a dinuclear complex. Fur-
ther, in 5 water is present in crystal lattice and this water mole-
cule exhibited strong interaction with hydrazinic nitrogen
atom, N2···H–OH 2.023 Å, and inhibited possible bridging by
this atom. In 6, there is no solvent present in the crystal lattice
but hydrazinic nitrogen is engaged in intermolecular interac-
tions with tmphen co-ligand, N2···H–C(tmphen) 2.610 and
2.723 Å. These different interactions might be responsible for
the formation of square pyramidal complexes 1, 5, 6 rather
than dinuclear complex 2.
Figure 6. Fluorescence spectra of complexes 2, 4, and 6.
Solution Phase Behavior
In complexes 1–6, πǞπ* and nǞπ* transitions lie in the
ranges 264–280 and 309–326 nm, respectively. The ligand-to-
metal charge-transfer bands are found in the range of 354–
Conclusions
396 nm. The higher energy bands at about 375 nm are assigned
Salicylaldehyde-N1-methyl (or ethyl) thiosemicarbazones
to SǞCu transition.[23] The band due to OǞCu transition bind to copper(II) as dianions by O, N3, S donor atoms. Com-
merges with d–d band (ν3) and appears at about 394 nm. In plexes 1 and 3–6 have square pyramidal arrangement, whereas
6
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Copper(II) Complexes with N1-Subsitituted Salicylaldehyde Thiosemicarbazones
[13] C. A. Hunter, J. K. Msanders, J. Am. Chem. Soc. 1990, 112, 5525.
[14] Y. Kim, J. H. Geiger, S. Hahn, P. B. Sigler, Nature 1993, 365,
512.
[15] J. L. Kim, D. B. Nikolov, S. K. Burley, Nature 1993, 365, 520.
[16] D. W. Christianson, W. N. Lipscomb, Acc. Chem. Res. 1989, 22,
62.
[17] I. H. Hall, K. G. Rajendran, D. X. West, E. Liberta, Anti-Cancer
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[18] M. Belicchi Ferrari, G. Gasparri Fava, P. Tarasconi, R. Albertini,
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[19] M. Belicchi Ferrari, G. Gasparri Fava, E. Leporati, G. Pelosi, R.
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complex 2 is a trigonal bipyramidal square planar (5:4) coordi-
nation pair. The presence of an ethyl group at N1 atom appears
to induce fluorescence properties in complexes 2, 4, and 6,
which could be attributed to the increase in donor ability of
the thio ligands assisting the co-ligands in fluorescence by way
of enhancing the life time of the excited state. The formation
of a trigonal bipyramidal square planar (5:4) involving N2-
bridging was observed first time in complexes of mono-thio-
semicarbazones.
[20] W. L. Kwik, K. P. Ang, H. S. O. Chan, V. Chebolu, S. A. Koch,
J. Chem. Soc., Dalton Trans. 1986, 2519.
Acknowledgements
[21] a) G. Filippini, A. Gavezotti, Acta Crystallogr., Sect. B 1993, 49,
868; b) A. Gavezotti, G. Filippini, J. Am. Chem. Soc. 1996, 118,
7153.
[22] a) A. D. Naik, P. A. N. Reddy, M. Nethaji, A. R. Chakravarty,
Inorg. Chim. Acta 2003, 349, 149; b) A. M. Thomas, A. D. Naik,
M. Nethaji, A. R. Chakravarty, Inorg. Chim. Acta 2004, 357,
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M. R. P. Kurup, Polyhedron 2004, 23, 2549; d) E. B. Seena,
M. R. P. Kurup, Polyhedron 2007, 26, 829.
Financial assistance from CSIR, (letter no. 09/254(0188)/2009–EMR–
I), New Delhi is gratefully acknowledged. The authors thank Matthias
Zeller of Youngstown State University, USA, for his contribution in
X-ray crystallography.
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Received: April 17, 2012
Published Online: ᭿
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T. S. Lobana et al.
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T. S. Lobana*, P. Kumari, R. J. Butcher, J. P. Jasinski,
J. A. Golen ......................................................................... 1–8
Metal Derivatives of Thiosemicarbazones: Crystal and Mole-
cular Structures of Mono- and Dinuclear Copper(II) Com-
plexes with N1-Subsitituted Salicylaldehyde Thiosemicarb-
azones
8
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