Synthesis, characterization and physicochemical properties of copper(II) complexes containing salicylaldehyde semicarbazone

Article abstract of DOI:10.1016/S0277-5387(03)00402-9

Copper(II) complexes containing a series of salicylaldehyde semicarbazone ligands have been prepared and characterized by a range of physicochemical techniques. The X-ray structure of [Cu(HBnz₂)Cl]·H ₂O (5) (where HBnz₂ is salicylaldehyde-N,N-dibenzyl semicarbazone) shows the complex is monomeric and the copper atom is four coordinated in a distorted square planar geometry. The ligand chelates the copper in a tridentate fashion through the imine N, carbonyl O and phenolato O with the fourth position being occupied by coordinated Cl. The compound [Cu(Ph₂)·H₂O] (4) (where Ph₂ is salicylaldehyde-N,N-diphenyl semicarbazone) is also formulated as a monomer whereas all other complexes are assumed to have a side-by-side dimeric arrangement of the metal chelating with the phenolate bridging the Cu(II) centres.

Full text of DOI:10.1016/S0277-5387(03)00402-9

Polyhedron 22 (2003) 2781Á2786
/
www.elsevier.com/locate/poly
Synthesis, characterization and physicochemical properties of
copper(II) complexes containing salicylaldehyde semicarbazone
Peng Foo Lee, Chang-Tong Yang *, Daming Fan, Jagadese J. Vittal,
John D. Ranford *
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
Received 22 April 2003; accepted 6 June 2003
Abstract
Copper(II) complexes containing a series of salicylaldehyde semicarbazone ligands have been prepared and characterized by a
range of physicochemical techniques. The X-ray structure of [Cu(HBnz2)Cl]×H2O (5) (where HBnz2 is salicylaldehyde-N,N-dibenzyl
semicarbazone) shows the complex is monomeric and the copper atom is four coordinated in a distorted square planar geometry.
/
The ligand chelates the copper in a tridentate fashion through the imine N, carbonyl O and phenolato O with the fourth position
being occupied by coordinated Cl. The compound [Cu(Ph2)×
/
H2O] (4) (where Ph2 is salicylaldehyde-N,N-diphenyl semicarbazone) is
also formulated as a monomer whereas all other complexes are assumed to have a side-by-side dimeric arrangement of the metal
chelating with the phenolate bridging the Cu(II) centres.
# 2003 Elsevier Ltd. All rights reserved.
Keywords: Copper(II) complexes; Salicylaldehyde semicarbazone; Crystal structures
1. Introduction
salicylaldehyde acetylhydrazone (H2sa) has also dis-
played biological activity [9,10].
Transition metal complexes with potential biological
activity are the focus of extensive investigation. Inter-
estingly, complexation with copper enhances the biolo-
In this paper we focus on the synthesis of a series of
analogues of H2sb and their Cu(II) complexes. The
ligands (Fig. 1) prepared include disubstituted com-
pounds where R1 and R2 are identical, where R1ꢀ
R2ꢀmethyl, ethyl, isopropyl, phenyl, benzyl or where
R1ꢀphenyl and R2ꢀH. Lastly, the complex where R1
and R2 were part of an aliphatic ring was also
synthesized, where the substituted group is pipyridine.
Compounds prepared have been characterized by a
range of physicochemical techniques.
/
gical activity of a wide variety of organic ligands [1Á
Such an example is the copper complex of salicylalde-
hyde benzoylhydrazone (H2sb), [Cu(Hsb)Cl]×H2O,
which exhibits tumour inhibitory activity [5].
[Cu(Hsb)Cl]×H2O was first found to be a potent
inhibitor of DNA synthesis and cell growth [6,7] in a
number of human and rodent cell lines [8]. The
cytotoxicity of this complex was discovered to exceed
many other compounds which were previously known to
possess such properties, including those used clinically.
The Cu(II) complex of the structurally related ligand
/
4].
/
/
/
/
/
2. Experimental
All reagents were commercially available and were
used as received. Solvents were dried by conventional
procedures prior to use. Reagents used for the physical
measurements were of spectroscopic grade. The yields
are reported with respect to the metal salts.
The 1H NMR spectra were recorded on a Bruker
ACF 300FT-NMR spectrometer using TMS as an
internal reference at 25 8C in DMSO and the Infrared
* Corresponding authors. Tel.: ꢁ
/
65-6874-2683; fax: ꢁ
/
65-6779-1691
(C.-T. Yang). Tel.:
Ranford).
ꢁ
/
65-6779-4241; fax: 65-6779-4241 (J.D.
ꢁ
/
E-mail
addresses:
chmyct@nus.edu.sg
kubalranford@yahoo.co.uk (J.D. Ranford).
(C.-T.
Yang),
0277-5387/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0277-5387(03)00402-9

2782
P.F. Lee et al. / Polyhedron 22 (2003) 2781Á2786
/
stirring over a period of 1 h. The reaction mixture was
left to stir for 30 min. before the solvents were removed
on a rotary evaporator at 60 8C. The solution was then
extracted with chloroform three times and the solvent
again removed by rotary evaporator to give the semi-
carbazide. A solution of the semicarbazide in ethanol (5
ml) was placed in an ice bath on a stirrer plate. To this
was added excess salicylaldehyde (16 mmol, 1.71 ml) in
ethanol (5 ml) dropwise with vigorous stirring, over a
period of 10 min. A yellow compound was obtained and
the reaction mixture was then filtered and washed with
cold water to remove excess salicylaldehyde. The yellow
product was then dried under vacuum until a constant
weight. Recrystallization was not carried out for fear of
Fig. 1. Salicylaldehyde-N,N-disubstituted semicarbazone.
product decomposition. Yields ranges from 80Á
/
90%.
spectra (KBr pellet) were recorded using a FTS165 Bio-
Rad FTIR spectrophotometer in the range 4000Á450
cmꢂ1. The electronic transmittance spectra were re-
corded on a Shimadzu UV-2501/PC UVÁVis spectro-
photometer in Nujol mull and MeOH solution.
Conductance measurements were made using a Kyoto
Electronics CM-115 conductivity meter using 1 mM
solutions. The elemental analyses were performed in the
Microanalytical Laboratory, Chemistry Department,
National University of Singapore. Water present in the
compounds was determined using a SDT 2980 TGA
thermal analyzer with a heating rate of 10 8C minꢂ1 in a
H2Me2×
/
1.5H2O: m.p. 164Á6 8C. Anal. Calc. for
/
/
C10H16N3O3.5: C, 51.0; H, 6.7; N, 18.0. Found: C,
51.3; H, 6.8; N, 17.9%. 1H NMR (DMSO-d6): d 2.91 (s,
/
6H), 6.85Á
/
6.90 (m, 2H), 7.20Á
/
7.25 (m, H), 7.35Á7.38
/
(m, H), 8.34 (s, H), 10.48 (s, H), 11.60 (s, H). IR (KBr,
cmꢂ1): n(OH) 3405; n(NH) 2919, n(COOꢂ)as 1646,
ns(COOꢂ) 1463, n(phenolic, CO) 1257.
H2Et2×
/
0.5H2O: m.p. 169Á71 8C. Anal. Calc. for
/
C12H18N3O2.5: C, 59.0; H, 7.3; N, 18.0. Found: C,
59.0; H, 7.4; N, 17.3%. 1H NMR (DMSO-d6): d 1.09 (t,
6H), 3.31 (q, 4H), 6.85Á
/
6.90 (m, 2H), 7.19Á7.25 (m, H),
/
7.34Á7.37 (m, H), 8.36 (s, H), 10.40 (s, H), 11.65 (s, H).
/
N2 atmosphere using a sample size of 5Á
Room-temperature magnetic susceptibility measure-
ments were carried out at a JohnsonÁMatthey magnetic
/
10 mg per run.
IR (KBr, cmꢂ1): n(OH) 3520; n(NH) 2982, n(COOꢂ)as
1643, ns(COOꢂ) 1475, n(phenolic, CO) 1281.
/
H2iPr2: m.p. 191Á2 8C. Anal. Calc. for C14H21N3O2:
/
susceptibility balance with Hg[Co(SCN)4] as standard.
Corrections for diamagnetism were made using Pascal’s
constants. The reported magnetic moments are per
Cu(II) ion.
C, 63.8; H, 8.1; N, 15.8. Found: C, 63.8; H, 8.0; N,
1
16.0%. H NMR (DMSO-d6): d 1.24 (d, 12H), 3.75 (m,
2H), 6.84Á
/
6.89 (m, 2H), 7.18Á
/
7.24 (m, H), 7.31Á7.34
/
(m, H), 8.32 (s, H), 10.32 (s, H), 11.75 (s, H). IR (KBr,
cmꢂ1): n(OH) 3446; n(NH) 2969, n(COOꢂ)as 1638,
ns(COOꢂ) 1469, n(phenolic, CO) 1267.
2.1. Preparation of ligands
H2Ph2: m.p. 198Á
/
9 8C. Anal. Calc. for C20H17N3O2:
C, 72.2; H, 5.1; N, 12.9. Found: C, 72.5; H, 5.2; N,
Disubstituted amine (15 mmol) was dissolved in dry
dichloromethane (25 ml) in a round bottom flask.
Triphosgene (5.25 mmol, 1.55 g) was dissolved in dry
methylene chloride (25 ml) in a two-necked round
bottom flask and pyridine (30 mmol, 2.43 ml) was
added to this solution. After placing a magnetic stirrer
bar into the triphosgene solution, the two flasks were
stoppered tightly. The triphosgene solution was placed
in an ice bath on top of a stirrer plate, while the flask
was constantly being flushed with N2 gas. Using a glass
syringe, the amine solution was added into the triphos-
gene solution over a period of 45 min to yield an orange
solution. The reaction was then left to stand at room
temperature (r.t.) for 3 days with constant N2 flushing to
give a yellow solution.
1
12.7%. H NMR (DMSO-d6): d 6.82Á7.42 (m, 14H),
/
8.30 (s, H), 10.40 (s, H), 11.28 (s, H). IR (KBr, cmꢂ1):
n(OH) 3436; n(NH) 2957, n(COOꢂ)as 1641, ns(COOꢂ)
1462, n(phenolic, CO) 1258.
H2Bnz2: m.p. 195Á
C, 73.6; H, 5.9; N, 11.6. Found: C, 73.5; H, 5.9; N,
1
11.7%. H NMR (DMSO-d6): d 4.51 (s, 4H), 6.84Á7.43
(m, 14H), 8.35 (s, H), 10.85 (s, H), 11.52 (s, H). IR (KBr,
cmꢂ1): n(OH) 3416; n(NH) 2854, n(COOꢂ)as 1634,
ns(COOꢂ) 1453, n(phenolic, CO) 1260.
/
6 8C. Anal. Calc. for C22H21N3O2:
/
H2Bip2: m.p. 153Á5 8C. Anal. Calc. for C13H17N3O2:
C, 59.7; H, 6.9; N, 16.3. Found: C, 59.9; H, 7.1; N,
1
16.1%. H NMR (DMSO-d6): d 1.49 (d, 4H) 1.58 (d,
/
2H), 3.39 (t, 4), 6.84Á
/
7.00 (m, 2H), 7.19Á7.25 (m, H),
/
To the solution of disubstituted carbamic acid chlo-
ride was added diethyl ether (63 ml) and this mixture
was added dropwise to a solution of hydrazine hydrate
(60 mmol, 1.87 ml) in ethanol (30 ml) with vigorous
7.34Á7.37 (m, H) 8.31 (s, H), 10.61 (s, H), 11.60 (s, H).
/
IR (KBr, cmꢂ1): n(OH) 3414; n(NH) 2856, n(COOꢂ)as
1628, ns(COOꢂ) 1466, n(phenolic, CO) 1264.

P.F. Lee et al. / Polyhedron 22 (2003) 2781Á
/
2786
2783
H2PhH: m.p. 188Á
C, 66.0; H, 5.0; N, 16.4. Found: C, 65.9; H, 5.1; N,
16.5%. 1H NMR (DMSO-d6): d 6.84Á
7.95 (m, 9H), 8.27
/
9 8C. Anal. Calc. for C14H13N3O2:
1.3. Found: C, 44.6; H, 4.7; N, 12.0; H2O, 1.3%. IR
(KBr, cm ꢂ1): n(OH) 3468, n(NH) 2854, nas(COOꢂ)
1624, ns(COOꢂ) 1393, n(phenolic, CO) 1285.
/
(s, H), 8.86 (s, H), 10.08 (s, H), 11.12 (s, H). IR (KBr,
cmꢂ1): n(OH) 3404; n(NH) 3050, n(COOꢂ)as 1651,
ns(COOꢂ) 1471, n(phenolic, CO) 1263.
2.2.7. [{Cu(HPhH)Cl}2] (7)
Light brown colour. Yield: 0.244 g (69%). Anal. Calc.
for C28H24N6O4Cl2Cu2: C, 47.4; H, 3.4; N, 12.0. Found:
C, 47.6; H, 3.4; N, 11.9%. IR (KBr, cm ꢂ1): n(NH)
2842, nas(COOꢂ) 1631, ns(COOꢂ) 1411, n(phenolic,
CO) 1266.
2.2. Preparation of complexes
The general procedure for complexes preparation is as
follows. To a solution of the salicylaldehyde semicarba-
zone (1.0 mmol) in dichloromethane (50 ml) was added
2.3. X-ray structure determination
dropwise a solution of CuCl2×/2H2O (1.00 mmol, 0.170
g) in methanol (20 ml) with vigorous stirring at r.t. The
reaction mixture was filtered cold to give the green or
brown complex which was then washed with diethyl
ether.
The diffraction experiments were carried out on a
Bruker AXS SMART CCD diffractometer. The pro-
gram SMART [11] was used for collecting frames of data,
indexing reflection and determination of lattice para-
meters, SAINT [11] for integration of the intensity of
reflections and scaling, SADABS [12] for absorption
correction and SHELXTL [13] for space group and
structure determination and least-squares refinements
on F2. Selected crystallographic data and refinement
details are displayed in Table 1.
2.2.1. [{Cu(Me2)}2]×
/
H2O (1)
Light brown colour. Yield: 0.216 g (78%). Anal. Calc.
for C20H24N6O5Cu2: C, 43.3; H, 4.3; N, 15.0; H2O, 3.8.
Found: C, 43.2; H, 4.3; N, 15.1; H2O, 3.7%. IR (KBr,
cm ꢂ1): n(OH) 3433, n(NH) 2862, nas(COOꢂ) 1631,
ns(COOꢂ) 1413, n(phenolic, CO) 1280.
2.2.2. [{Cu(HEt2)Cl}2] (2)
3. Results and discussion
Light brown colour. Yield: 0.270 g (81%). Anal. Calc.
for C24H32N6O4Cl2Cu2: C, 43.2; H, 5.0; N, 12.4. Found:
C, 43.2; H, 4.8; N, 12.6%. IR (KBr, cm ꢂ1): n(NH)
2847, nas(COOꢂ) 1616, ns(COOꢂ) 1390, n(phenolic,
CO) 1256.
3.1. Synthesis
The synthetic route for the disubstituted ligands
required moisture-free and oxygen-free conditions as it
2.2.3. [{Cu(HiPr2)Cl}2]×
/
4H2O (3)
Table 1
Crystallographic data and structure refinement details for 5
Green colour. Yield: 0.258 g (65%). Anal. Calc. for
C28H48N6O8Cl2Cu2: C, 42.6; H, 6.0; N, 10.4; H2O, 9.0.
Found: C, 42.3; H, 6.0; N, 10.5; H2O, 9.1%. IR (KBr,
cm ꢂ1): n(OH) 3440, n(NH) 2929, nas(COOꢂ) 1618,
ns(COOꢂ) 1406, n(phenolic, CO) 1263.
Complex
Formula
fw
5
C22H22N3O3Cl Cu
475.42
293(2)
T (K)
˚
Wavelength, l (A)
Crystal system
Space group
0.71073
monoclinic
P21/c
2.2.4. [Cu(Ph2)×
/
H2O] (4)
Green colour. Yield: 0.353 g (86%). Anal. Calc. for
C20H17N3O3Cu: C, 58.3; H, 4.0; N, 10.2; H2O, 4.3.
Found: C, 58.5; H, 4.1; N, 10.2; H2O, 4.4%. IR (KBr,
cm ꢂ1): n(OH) 3420, n(NH) 2849, nas(COOꢂ) 1598,
ns(COOꢂ) 1374, n(phenolic, CO) 1261.
Unit cell dimensions
˚
a (A)
˚
18.9212(1)
7.1327(1)
16.0490(1)
100.05(1)
2132.70(3)
4
b (A)
˚
c (A)
b (8)
3
V (A )
˚
Z
2.2.5. [Cu(HBnz2)Cl]×
/
H2O (5)
rcalc (g cmꢂ3
)
1.481
1.178
Dark green colour. Yield: 0.342 g (72%). Anal. Calc.
for C22H22N3O3ClCu: C, 58.1; H, 5.0; N, 9.3; H2O, 4.1.
Found: C, 58.3; H, 4.9; N, 9.3; H2O, 4.0%. IR (KBr, cm
ꢂ1): n(OH) 3461, n(NH) 2855, nas(COOꢂ) 1603,
ns(COOꢂ) 1378, n(phenolic, CO) 1270.
Absorption coefficient (mmꢂ1
Reflections collected
Independent reflections
Rint
)
13074
5212
0.0242
1.023
Goodness-of-fit
a
Final [I ꢀ
/2s], R1
0.0385
0.0943
b
wR2
2.2.6. [{Cu(HBiP)Cl}2]×
/
0.5H2O (6)
a
Dark green colour. Yield: 0.260 g (80%). Anal. Calc.
for C26H33N6O4.5Cl2Cu2: C, 44.8; H, 4.6; N, 12.0; H2O,
R1ꢀ
wR2ꢀ
/
SjjFo½ꢂ
/
½Fcjj/SjFoj.
b
/
[S w(Fo2ꢂFc2)2/S w(Fo2)2]1/2
.

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P.F. Lee et al. / Polyhedron 22 (2003) 2781Á2786
/
involves the use of triphosgene which is sensitive to both
of these. Hence, reactions had to be carried out in the
dry box, under a nitrogen atmosphere and at ice
temperature in order to minimize the possibility of
undesired products. Complexation was relatively
straightforward, however, the choice of solvent for the
ligands was important. Initially ethanol was chosen but
it was not satisfactory as gentle heating was required for
complete solubilization which was not recommended as
decomposition might occur. A series of solvents were
tested and dichloromethane was selected as the most
suitable.
Table 2
˚
Selected bond lengths (A) and bond angles (8) for 5
Bond lengths
Cu(1)Á/O(1)
1.902(2) Cu(1)Á
1.974(2) Cu(1)Á
1.290(3) N(1)Á
1.363(3) N(3)Á
1.327(2) C(8)Á
/
N(1)
1.941(2)
2.222(6)
1.378(2)
1.343(3)
1.261(2)
Cu(1)Á/O(2)
/Cl(1)
N(1)Á
N(2)Á
O(1)Á
/
C(7)
/
N(2)
/C(8)
/
C(8)
/C(1)
/
O(2)
Bond angles
O(1)ÁCu(1)Á
N(1)ÁCu(1)Á
N(1)ÁCu(1)Á
C(7)ÁN(1)Á
N(2)ÁN(1)Á
C(8)ÁN(3)Á
C(9)ÁN(3)Á
C(8)ÁO(2)Á
/
/
N(1)
O(2)
92.3(7) O(1)Á
80.8(6) O(1)Á
170.2(5) O(2)Á
118.6(2) C(7)Á
112.8(1) C(8)Á
117.8(2) C(8)Á
121.3(2) C(1)Á
113.5(1) O(1)Á
/
Cu(1)Á
Cu(1)Á
Cu(1)Á
N(1)Á
N(2)Á
N(3)Á
O(1)Á
C(1)Á
/
O(2)
Cl(1)
Cl(1)
172.3(6)
91.4(4)
96.0(5)
/
/
/
/
/
/
Cl(1)
/
/
/
/
N(2)
/
/
Cu(1)
N(1)
C(16)
128.6(1)
113.8(2)
119.7(2)
127.8(1)
124.4(2)
/
/
Cu(1)
/
/
/
/
C(9)
/
/
3.2. Description of crystal structure [Cu(HBnz2)Cl]×
/
/
/
C(16)
/
/
Cu(1)
/
/
Cu(1)
/
/
C(6)
H2O (5)
An ORTEP diagram of the structure is shown in Fig. 2.
Selected bond lengths and angles are given in Table 2.
The structure of 5 shows the copper atom is four
coordinated and is best described as having a distorted
square planar geometry with a NO2Cl donor set. The
3.3. Physical characterization
The IR absorption band in the region 3400Á3500
/
cmꢂ1 confirms the hydrates in all the complexes except
2 and 7 [16]. This is further supported by the weight loss
observed in thermogravimetry, TG. For all the com-
ligand chelates the copper in an tridentate fashion
˚
emplying the imine N (Cu(1)ÁN(1) 1.941(2) A), carbon-
/
˚
yl O (Cu(1)Á
/
O(2) 1.974(2) A), and phenolato O (Cu(1)Á
/
˚
O(1) 1.902(2) A). The last position is occupied by
plexes, the sharp band in the region 2842Á
has been assigned to NÁH stretching modes [17]. The
band in the region 1598Á
1631 cmꢂ1 is due to the
asymmetric vibration of coordinated carboxylate group
[nas(CO2ꢂ)] and the band in the region 1374Á1413 cmꢂ1
/
2929 cmꢂ1
˚
Cl(1) 2.222(6) A). The angles
/
coordinated Cl (Cu(1)Á
/
/
[O(1)ÁCu(1)ÁO(2), 172.3(6)8] and [N(1)Á
/
/
/
Cu(1)ÁCl(1)
/
170.2(5)8] at Cu(1) support the square planar geometry.
The bond angle and length data for 5 agree with the
/
equivalent values of those for CuCl(H2saladhp)×
(H3saladhpꢀ1,3-dihydroxy-2-methyl-(salicylidenea-
mino)-propane) [14] and [CuCl(Hsbh)]×H2O (H2sbhꢀ
salicylaldehyde benzoylhydrazone) [15].
The OÁH protons of lattice water are involved in
strong and weak inter-molecular hydrogen-bonding to
/
H2O
may be attributed to the symmetric stretching vibration
of carboxylate group [ns(CO2ꢂ)]. For all the complexes,
the difference between nas(COOꢂ) and nsym(COOꢂ)
/
/
/
stretching frequencies is ꢀ
a terminal coordination mode for the carboxylate group
[18Á20]. This observation was confirmed by the X-ray
/
200 cmꢂ1, thus suggesting
/
/
˚
the O atom [O(1S)Á
/
H(1S)ꢀ ꢀ ꢀO(1), 2.45 A; O(1S)Á
/
structure of 5.
˚
H(2S)ꢀ ꢀ ꢀO(1), 2.11 A] of the carbonyl group and
Electronic spectral data in Nujol mull are given Table
4 along with molar conductivity and room temperature
magnetic data. The mull transmittance spectra exhibit a
charge transfer transition (CT) at approximately 400
nm, often being poorly resolved shoulders. The band is
similar to that found for the related Cu(Hsb)ꢁ [4] and
Cu(Hsa)ꢁ [5] complexes which was assigned to a ligand
to copper(II) transition. This band may also contain a
˚
chloride atom [O(1S)Á
/
H(1S)ꢀ ꢀ ꢀCl(1), 2.48 A] in an
adjacent molecule. The H atom of the protonated amide
participates in strong intermolecular hydrogen-bonding
˚
to oxygen O(1S) [N(2)Á
/
H(2)ꢀ ꢀ ꢀO(1S), 2.04 A] of lattice
water. Hydrogen bond parameters for 5 are given in
Table 3.
Cl0
/
Cu ligand-to-metal CT component for 2, 3, 5, 6 and
d absorption bands at 630, 620
and 630 nm for 1, 4 and 5, respectively, were assigned to
7, respectively. The dÁ
/
the square planar geometry [21] as seen in the crystal
structure of 5. The rather broad dÁd absorption band
/
(ca. 670 nm) for 2, 3, 6 and 7 was assigned to a square
pyramidal geometry, as present in related copper(II)
complexes [4,5].
For all the complexes, molar conductivity values in
DMSO fall below the range expected for 1:1 electrolytes
Fig. 2. An ORTEP view showing the coordination environment of 5.
suggesting that the counterÁions remained bound to the
/

P.F. Lee et al. / Polyhedron 22 (2003) 2781Á
/
2786
2785
Table 3
Hydrogen bond distances (A) and bond angles (8) in 5
˚
DÁ
/
H
d(DÁ
/
H)
d(Hꢀ ꢀ ꢀA)
ꢀ
/
DHA
d(Dꢀ ꢀ ꢀA)
A
Symmetry
[ꢂxꢁ1, ꢂ
N2Á
O1SÁ
O1SÁ
O1SÁ
/
H2
0.86
0.70
0.70
0.75
2.04
2.45
2.48
2.11
145
126
166
171
2.784(2)
3.115(2)
3.464(2)
2.815(2)
O1S
O1
/
/
/
yꢁ
/
1, ꢂ
/
zꢁ1]
/
/
H1S
H1S
H2S
/
Cl1
O1
/
[ꢂ
/
xꢁ
/
1, yꢂ
/1/2, ꢂ
/zꢁ1/2]
/
Table 4
Magnetic, electronic absorption and conductivity data for complexes
Complex
Absorption bands a
Molar conductivity b (S cm2 molꢂ1
)
Magnetic moment mB (BM)
CT
dÁ/d
1
2
3
4
5
6
7
390 (sh)
395 (sh)
405 (sh)
400 (sh)
400 (sh)
385 (sh)
400 (sh)
630 (br)
680 (br)
670 (br)
620 (br)
630 (br)
670 (br)
675 (br)
19
18
28
17
20
21
21
1.39
1.50
1.44
1.83
2.03
1.35
1.47
a
As Nujol mull transmittance.
In DMSO.
b
complexes even in such a strongly coordinating solvent
[22]. There is continued interest in the magnetic proper-
ties of di- and oligomeric Cu(II) complexes from
theoretical and biological viewpoints [23,24]. Complexes
4 and 5 have normal moments (1.83mB for 4 and 2.04mB
for 5) and are consistent with uncoupled Cu(II) ions
formulated as monomers. All other complexes have
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 200158. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2
lower magnetic moments (1.35Á/1.50mB) indicating an
1EZ, UK (fax: ꢁ44-1223-336033; e-mail: deposit@
/
antiferromagnetic coupling and have been assumed a
side-by-side arrangement of the metal chelates with
phenolato bridges between the Cu(II) centres, as found
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
in [{Cu(Hsa)(H2O)}2]×
/
(NO3)2 [5]. Cytotoxicity testing is
Acknowledgements
presently being conducted.
This research was supported by Grant RP970614
from the National University of Singapore.
4. Summary
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/
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