Spectroscopic and structural study of some 2,5-hexanedione bis(salicyloylhydrazone) complexes: Crystal structures of its Ni(II) and Cu(II) complexes and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxy-benzamide

Article abstract of DOI:10.1016/j.saa.2014.02.195

The reaction between 2,5-hexanedione and salicylic acid hydrazide produced two compounds: 2,5-hexanedione bis(salicyloylhydrazone) [HDSH] (ethanol insoluble) and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide [DPH] (ethanol soluble). HDSH formed compl

Full text of DOI:10.1016/j.saa.2014.02.195

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 129 (2014) 307–313
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Spectroscopic and structural study of some 2,5-hexanedione
bis(salicyloylhydrazone) complexes: Crystal structures of its Ni(II) and
Cu(II) complexes and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxy-
benzamide
⇑
Bakir Jeragh , Ahmed A. El-Asmy
Chemistry Department, Faculty of Science, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
The Cu(II) complex was found square-planar; the ligand coordinates through two nitrogens and two oxy-
gens forming one seven and two five membered rings.
ꢀ
New transition metal complexes of
2,5-hexanedione
bis(thiosemicarbazone).
ꢀ
ꢀ
XRD structure of -1-(2,5-dimethyl-
1H-pyrrol-yl-2-hydroxynenzamide.
Octahedral and square-planar
structures for [Ni(HDSH-
2H)(EtOH)(H2O)] and [Cu(HDSH-2H)].
Crystal structure of [Cu(HDSH-2H)]
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction between 2,5-hexanedione and salicylic acid hydrazide produced two compounds: 2,5-hexane-
dione bis(salicyloylhydrazone) [HDSH] (ethanol insoluble) and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-
hydroxybenzamide [DPH] (ethanol soluble). HDSH formed complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II),
Hg(II) and Pd(II) which are characterized by elemental analyses, spectra (IR, 1H NMR, ESR and MS), thermal
and magnetic measurements. The crystals of [Ni(HDSH-2H)(EtOH)(H2O)] and [Cu(HDSH-2H)] were solved
having octahedral and square-planar geometries, respectively. The other complexes have the formulae
[Co(HDSH-2H)(H2O)2], [Cu(HDSH-H)2], [Zn(HDSH-2H)(H2O)2], [Cd2(HDSH-4H)(H2O)4], [Cd2(HDSH-
2H)(H2O)4Cl2]; [Hg(HDSH-2H)] and [Pd2(HDSH-4H)(H2O)4]. The obtained complexes are stable in air and
non-hygroscopic. The magnetic moments and electronic spectra of the complexes provide different geom-
etries. The ESR spectra support the mononuclear geometry for [Cu(HDSH-2H)] and [Cu(HDSH-H)2]. The
thermal decomposition of the complexes revealed the coordinated waters as well as the end product which
is in most cases the metal oxide. The crystal structure of N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxyben-
zamide is solved by X-ray technique.
Received 21 December 2013
Received in revised form 27 January 2014
Accepted 19 February 2014
Available online 13 March 2014
Keywords:
2,5-Hexanedione bis(salicyloylhydrazone)
Spectra
X-ray structure
ESR
N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-
hydroxybenzamide
Ó 2014 Elsevier B.V. All rights reserved.
⇑
Corresponding author.
E-mail address: bakir.jeragh@ku.edu.kw (B. Jeragh).
http://dx.doi.org/10.1016/j.saa.2014.02.195
1386-1425/Ó 2014 Elsevier B.V. All rights reserved.

308
B. Jeragh, A.A. El-Asmy / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 129 (2014) 307–313
N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide is pro-
Introduction
duced. This compound is isolated as crystals suitable for X-ray dif-
fraction. The crystal of N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-
hydroxybenzamide was formed with Pbca (#61) space group having
orthorhombic crystal system as shown in Fig. 1 and Table 1. The N1–
N2, O1–C2 and O2–C7 are 1.379, 1.362 and 1.230, respectively.
Some selected bond lengths and bond angles are presented in
Table 2.
There is a continuous interest of the chemistry of hydrazones
and their complexes because of their pharmacological, antitumour,
fungicide, bactericide, anti-inflammatory and antiviral activities
[1,2]. Great attention has been focused on the structural investiga-
tion of this class of compounds [3].
The complexes of salicylaldehydeisobutroyl hydrazone (SIBuH)
and o-hydroxyacetophenoneisobutyroyl hydrazone (HAIBuH) were
prepared and structurally characterized forming octahedral geome-
Synthesis of the complexes
try:
[Ni(SIBuH)2],
[Ni(HAIBuH)2],
[Co(SIBuH)(OAc)–(H2O)];
low-spin octahedral: [Cu(SIBuH)2]ꢁH2O, [Co(HAIBuH)2] and
square-planar: [Cu(AIBuH)–(H2O)] [4]. Square-planar geometry for
Cu2+ and octahedral for Ni2+ and Co2+ complexes [M(HSS)2]
The complexes were prepared by adding a solution of the ligand
(3 mmol), dissolved in 20 ml absolute ethanol to a solution of the
metal salt (3 mmol) in 30 ml absolute ethanol and severely stirred
on a hot plate under reflux for 2–4 h. The binuclear complexes
were prepared by heating a mixture of the ligand (3 mmol) and
the metal salts (6 mmol) in 30 ml aqueous–ethanol solution (v/v)
on a water bath for 4–6 h. After completion of the reaction, the pre-
cipitate was filtered off, washed with ethanol, diethyl ether and fi-
nally dried. The single crystals of the Ni(II) and Cu(II) complexes
were grown by slow evaporation technique in DMSO/ethanol solu-
tion. To isolate the Co(II) complex, water is added to help in the
precipitation. No crystals are formed in the rest of the complexes
and the trials are continued.
(M = Cu2+, Co2+, Mn2+, VO2+, TiO2+), [M0(SS)] (M0 = Cu2+, Ni2+, Co2+
)
and [Cu(HSS)] were synthesized with salicylaldehydesalicyloyl
hydrazone [5]. 2-Aceto-1-naphthol-N-salicoyl hydrazone was used
for the microdetermination of metal ions in solution [6]. Salicalde-
hydefuronyl hydrazone behaved as a dibasic ONO forming [Ni(L)
(H2O)2], [Co(L)(H2O)2], [CuL], [Zn(L)(H2O)], [Zr(OH)2(L)–(CH3OH)2],
[Zr(OH)2(HL)2], [MoO(L)Cl] and [UO2(L)(CH3OH)]. The Cu2+ and
Mo(V)O complexes have subnormal magnetic moments with
antiferromagnetic interaction [7]. Mn2+, Co2+, Ni2+, Cu2+ and Zn2+
complexes of salicylidene-N-cyanoaceto hydrazone, H2L1 and 2-hy-
droxy-l-naphthylidene-N-cyanoaceto hydrazone, H2L2 were found
having octahedral geometries, except for [Co(HL2)OAc] which has
a tetrahedral structure [8].
Physical measurements
[VO(H2L)]ꢁ2H2O, [Ni(H2L)]ꢁ3H2O, [Zn(H2L)], [Ni(H4L)Cl2]ꢁ2H2O
Elemental analyses (C, H and N) of HDSH and its complexes
were measured at the Microanalytical Unit on VarianMicro
V1.5.8, CHNS Mode, 15073036 of Kuwait University. Metal con-
tents were estimated using ICP-OES GBC Quantum Sequential.
The FT-IR spectra were recorded as KBr disc on a FT/IR-6300 type
A (400–4000 cmꢂ1). The electronic spectra of the complexes were
recorded on Cary 5 UV–Vis Spectrophotometer, Varian (200–
900 nm). The 1H and 13C NMR spectra of the ligand and its diamag-
netic complexes were recorded in DMSO-d6, on a Bruker WP 200
SY spectrometer (300 MHz) at room temperature using tetrameth-
ylsilane (TMS) as an internal standard. The magnetic measure-
ments were carried out on a Johnson–Matthey magnetic balance,
UK. Thermogravimetric analysis (TGA) was measured (10–850 °C)
on a Shimadzu TGA-60; the nitrogen flow and heating rate were
50 ml/min and 10 °C minꢂ1, respectively. The ESR spectra were ob-
tained on a Bruker EMX Spectrometer working in the X-band
(9.66 GHz) with 100 kHz modulation frequency. The microwave
power was set at 2.00e + 02 mW. A powder spectrum was obtained
in a 2 mm quartz capillary at room temperature.
and [Cr2(H2L)(OAc)2(OH)2]ꢁ2H2O, [Cu(H4L)(H2L)(EtOH)2]ꢁ2H2O,
[Co2(H2L)(OAc)2]ꢁH2O,
[Mn2(H2L)(OH)2]ꢁH2O
[Cu2(H2L)(OAc)2
(H2O)6], and [Co2(H2L)(H2O)4Cl2]ꢁ2H2O were isolated with 2,5-hex-
anedione bis(salicyloylhydrazone) [H4L] and characterized by
elemental analyses, spectral (IR, 1H NMR, ESR and MS), thermal
and magnetic measurements [9].
Extension to the work done on 2,5-hexanedione bis(salicyl-
oylhydrazone) and its metal complexes [9], the present paper aims
to synthesize enol-form complexes. Also, N-(2,5-dimethyl-1H-pyr-
rol-1-yl)-2-hydroxybenzamide was isolated and structurally
investigated.
Experimental
2,5-Hexanedione, salicaldehyde, hydrazine hydrate, CoCl2ꢁ
6H2O, NiCl2ꢁ6H2O, CuCl2ꢁ2H2O, Cu(OAc)2-ꢁH2O, CdCl2ꢁ2H2O, ZnCl2ꢁ
2H2O, HgCl2 and K2PdCl4 were used as supplied. Ethanol, diethyl-
ether and dimethylsulphoxide were Merk products and directly
used.
X-ray crystallography
Results and discussion
The X-ray single-crystal diffraction data were collected on a
Characterization of the complexes
Rigaku R-AXIS RAPID diffractometer using filtered Mo Ka radiation.
The structure was solved by the direct methods and expanded
using Fourier techniques at Kuwait University. Crystallographic
data and details of the data collection and structure refinements
are listed in Table 1.
General
In previous work [9], we reported [VO(H2L)]ꢁ2H2O, [Ni(H2L)]ꢁ
3H2O, [Zn(H2L)], [Ni(H4L)Cl2]ꢁ2H2O and [Cr2(H2L)(OAc)2(OH)2]ꢁ
2H2O, [Cu(H4L)(H2L)(EtOH)2]-ꢁ2H2O, [Co2(H2L)(OAc)2]ꢁH2O, [Mn2
(H2L)(OH)2]ꢁH2O [Cu2(H2L)(OAc)2(H2O)6], and [Co2(H2L)(H2O)4Cl2]ꢁ
2H2O with the same ligand. Here, we aim to isolate different
complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and Pd(II)
ions and to prove their structures by X-ray crystallography. The
formed complexes have the formulae: [Co(HDSH-2H)(H2O)2],
[Ni(HDSH-2H)(EtOH)(H2O)], [Cu(HDSH-2H)], [Cu(HDSH-H)2], [Zn
(HDSH-2H)(H2O)2], [Cd2(HDSH-4H)(H2O)4], [Cd2(HDSH-2H)(H2O)4
Cl2]; [Hg(HDSH-2H)] and [Pd2(HDSH-4H)(H2O)4] (Table 3). The
complexes are insoluble in most common organic solvents and
are completely soluble in DMSO.
Synthesis of HDSH and DPH
The two ligands were prepared by adding 0.05 mol of 2,5-hex-
anedione to 0.1 mol of salicylic acid hydrazide, in 50 ml ethanol
with continuous stirring. The reaction mixture was heated under re-
flux on a water bath for 2 h. The precipitate formed was separated
by filtration, recrystallized from ethanol, dried and characterized
as HDSH. On gathering the filtrate and concentrated by evaporation,
a new compound with empirical formula C13H14N2O2 and name

B. Jeragh, A.A. El-Asmy / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 129 (2014) 307–313
309
Table 1
Summary of the crystallographic data and structure analysis.
Parameters
N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxy-benzamide
13H14N2O2
[Ni(HDSH-2H)(EtOH)(H2O)]
[Cu(HDSH-2H)]
Empirical formula
Formula weight
Crystal color, habit
Crystal dimensions
Crystal system
C
C22H28N4O6Ni
503.19
Colorless, prism
0.20 ꢅ 0.06 ꢅ 0.03 mm
Triclinic
C20H20CuN4O4
443.95
Colorless, needle
230.27
Colorless, prism
0.20 ꢅ 0.20 ꢅ 0.20 mm
Orthorhombic
Primitive
0.20 ꢅ 0.04 ꢅ 0.02 mm
Monoclinic
Lattice type
Primitive
Primitive
Lattice parameters
a = 13.4738(6)
b = 15.3097(8)
c = 24.903(2)
a = 8.252(3) Å
b = 11.807(4) Å
c = 27.583(9) Å
a = 7.322(1) Å
b = 16.918(3) Å
c = 15.631(2) Å
a
= 93.109(9)°
b = 107.40(1)°
b = 95.957(7)°
c
= 110.358(8)°
V = 5136.9(5)
Pbca (#61)
16
V = 2366(2) Å3
Pꢂ1 (#2)
4
V = 1925.7(5) Å3
P21/n (#14)
4
Space group
Z value
Dcalc
1.191 g/cm3
1952.00
1.412 g/cm3
1056.00
1.531 g/cm3
916.00
F000
l(Mo K
a)
0.817 cmꢂ1
8.646 cmꢂ1
11.697 cmꢂ1
Fig. 1. N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide.
X-ray crystal structure of the Ni(II) and Cu(II) complexes
(i) The t
(C@N) vibration observed at 1625 cmꢂ1 in the ligand
spectrum shifted to lower wavenumbers (1581–
The structures of [Ni(HDSH-2H)(EtOH)(H2O)] and [Cu(HDSH-
2H)] are shown in Figs. 2 and 3. The parameters of the crystals
are presented in Table 1 while the selected bond lengths and an-
gles are summarized in Table 2. The Ni(II) and Cu(II) complexes
have P1 (#2) and P21/n (#14) space groups, respectively. Ni(II)
has six-coordination being bonded to two pairs of oxygen and
nitrogen atoms from the ligand and completed its hexa-coordina-
tion with one water and one ethanol molecule. Its bond angles of
O2ANiAO4; O2ANiAO5; O2ANiAO6; O2ANiAN2; O4ANiAO5
and O4ANiAO6 are 94.9; 89.1; 90.4; 78.7; 94.1 and 87.6, respec-
tively. Those of O4ANiAN2 and O5ANiAO6 are 173.7; 173.4 and
178.3 corresponding to the octahedral geometry. On the other
hand, the angles of Cu(II) complex are O2ACuAO3 (91.65);
O2ACuAN2 (82.00) O2ACuAO3 (91.65); O2ACuAN3 (158.31);
O3ACuAN2 (169.53); O3ACuAN3 (82.54) and N2ACuAN3
(106.34). The values indicate a distortion for N2ACuAN3 rather
than O2ACuAO3 in the square-planar geometry.
1610 cmꢂ1) in all complexes with the appearance of a new
band at 408–433 cmꢂ1 due to
t
(MAN) indicating the partic-
ipation of this group in bonding [10].
(ii) The (OH) vibration not altered strongly in the spectra of
t
complexes and appeared as medium or broad band more
or less at the same position in HDSH (ꢃ3290 cmꢂ1) as well
as the appearance of d(OH) at 1357–1378 cmꢂ1 as observed
in the ligand spectrum (1378 cmꢂ1).
(iii) In the spectra of [Pd2(HDSH-4H)(H2O)4] and [Cd2(HDSH-
4H)(H2O)4], the t(OH) and d(OH) bands disappear revealing
the deprotonation of the phenolic OH and its participation
in bonding.
(iv) In most complexes, the (C@O) and (NH) bands appearing at
1644 and 3038 cmꢂ1 in the ligand spectrum disappear in the
spectra of complexes indicating the enolization of amide
group (CONH) and the participation of CAO group in coordi-
nation. Evidence for oxygen donor is the appearance of new
bands at 1531–1577 and 1223–1258 cmꢂ1 due to
and (CAO) vibrations [11].
(v) The appearance of bands due to
t
(C@Nꢄ)
FT-IR and 1H NMR spectra of the complexes
t
t
(MAO) at 520–530 cmꢂ1
Examining the IR spectra of the complexes (Table 4) one may
conclude the following observations:
[12] in the spectra of all complexes is further support for oxy-
gen coordination. The bands at ꢃ3290, ꢃ930 and ꢃ600 cmꢂ1

310
B. Jeragh, A.A. El-Asmy / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 129 (2014) 307–313
Table 2
Some selected bond lengths (Å) and bond angles of Ni(II) and Cu(II) complexes.
Bond length of Ni(II) complex Å
Bond angles of Ni(II) complex (o)
Bond length of Cu(II) complex
Å
Bond angles of Cu(II) complex (o)
NiAO2
NiAO5
NiAN2
NiAO8
NiAO11
NiAN6
O1AC3
O3AC16
O5AC21
O8AC23
O10AC36
N1AN2
N2AC8
N3AC12
N5AN6
N6AC30
N7AC34
2.074(5)
2.126(7)
2.030(10)
2.032(5)
2.151(6)
2.071(8)
1.372(16)
1.347(14)
1.406(18)
1.314(11)
1.285(10)
1.411(8)
1.306(16)
1.265(15)
1.399(10)
1.294(16)
1.294(16)
O2ANiAO4
O2ANiAO6
O2ANiAN3
O4ANiAO6
O4ANiAN3
O5ANiAN2
O6ANiAN2
N2ANiAN3
O2ANiAO5
O8ANiAO10
O4ANiAO5
O5ANiAO6
94.9(3)
90.4(2)
173.7(4)
87.6(3)
79.4(3)
84.4(3)
93.9(3)
107.0(4)
89.1(3)
95.5(3)
94.1(3)
178.3(3)
CuAO2
CuAN2
O1AC2
O3AC12
N1AN2
N2AC8
N3AC11
C1AC2
C1AC7
C3AC4
C5AC6
C8AC19
C10AC11
C12AC13
C13AC18
C15AC16
C17AC18
1.921(4)
1.954(4)
1.350(8)
1.286(6)
1.402(6)
1.292(7)
1.292(6)
1.400(7)
1.457(8)
1.363(9)
1.375(8)
1.482(8)
1.506(7)
1.479(7)
1.402(7)
1.380(7)
1.378(7)
O2ACuAO3
O2ACuAN3
O3ACuAN3
CuAO2AC7
CuAO3AC12
N2AN1AC7
CuAN2AN1
CuAN2AC8
N1AN2AC8
CuAN3AN4
CuAN3AC11
91.65(14)
158.31(16)
82.54(14)
111.3(3)
110.8(3)
110.3(4)
112.4(3)
129.4(4)
118.1(4)
109.9(3)
133.8(4)
Some bond length of N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide(Å)
O1
O3
N1
N2
N3
N4
C2
1.362(3)
1.357(3)
1.379(3)
1.380(3)
1.385(3)
1.367(3)
O2
C7
C20
C7
C11
C20
C24
1.230(2)
1.226(2)
1.347(3)
1.373(3)
1.344(3)
1.377(3)
C15
N2
C8
N4
C21
O4
N1
N2
N3
N4
Some bond angles of N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide(°)
N2AN1AC7
N1AN2AC11
N4AN3AC20
N3AN4AC24
C2AC1AC6
C6AC1AC7
O1AC2AC3
120.18(14)
124.08(18)
121.29(14)
123.42(18)
117.72(18)
116.30(15)
120.86(15)
N1AN2AC8
124.52(18)
111.40(18)
124.91(19)
111.42(19)
125.97(17)
119.21(17)
119.93(18)
C8AN2AC11
N3AN4AC21
C21AN4AC24
C20C1AC7
O1AC2AC1
C1AC2AC3
Table 3
Elemental analysis of HDSH and its complexes.
Compound
HDSH
M.F Calcd. (Founda)
Color
C Calcd. (Found)
H Calcd. (Found)
N Calcd. (Found)
M Calcd. (Found)
384.44
383
477.40
Pale yellow
Brown
62.48
(62.10)
50.31
(50.64)
35.47
(35.30)
41.18
6.29
(5.94)
5.49
(5.32)
4.17
(3.58)
3.80
14.57
(14.32)
11.74
(11.56)
8.26
[Co(HDSH-2H)(H2O)2]
[Cd2(HDSH-4H)(H2O)4]
[Hg(HDSH-2H)]
12.35
(12.00)
677.29
583.23
Pale orange
Orange
(7.48)
9.61
(41.21)
49.44
(48.95)
52.88
(53.09)
32.10
(31.52)
53.86
(53.70)
57.85
(57.82)
36.11
(3.72)
5.39
(4.72
5.98
(5.57)
4.04
(3.69)
4.97
(4.21)
5.58
(4.98)
3.94
(9.37)
11.53
(10.33)
11.09
(11.04)
7.49
(7.41)
12.56
(11.94)
13.49
(12.82)
8.42
[Zn(HDSH-2H)(H2O)2]
[Ni(HDSH-2H)(EtOH)(H2O)]
[Cd2(HDSH-2H)Cl2(H2O)4]
[Cu(HDSH-2H)]
485.82
(485)
505.25
(438)
748.20
(665)
445.97
(443)
Buff
13.45
(13.13)
11.62
(12.12)
30.04
(30.31)
14.25
Pale brown
Beige
Green
(14.90)
[Cu(HDSH-H)2]
830.41
Brown
[Pd2(HDSH-4H)(H2O)4]
665.283
Dark brown
(36.17)
(3.91)
(8.82)
a
Values from MS.
in the spectra of [Cd2(HDSH-4H)(H2O)4], [Zn(HDSH-
2H)(H2O)2], [Cd2(HDSH-2H)(H2O)4Cl2] and [Pd2(HDSH-
the deprotonation and enolization of OH and CONH groups.
On deuteration, the OH signal disappeared in all spectra
(Table 5).
4H)(H2O)4] are attributed to
coordinated water [13].
t(OH), qr(H2O) and qw(H2O) of
(vi) The 1H NMR spectra of [Zn(HDSH-2H)(H2O)2] and
[Hg(HDSH-2H)] showed the signal of the OH protons at
(13.825; 11.473) and 11.831 ppm. This signal is disappeared
together with that of NH proton in the spectra of [Cd2
(HDSH-4H)(H2O)4] and [Pd2(HDSH-4H)ꢁ3H2O] confirming
Spectral and magnetic studies
The electronic spectral bands, measured in DMSO, with the
magnetic moments of the complexes are given in Table 6; DMSO
has no effect on the color. The spectrum of HDSH showed the

B. Jeragh, A.A. El-Asmy / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 129 (2014) 307–313
311
Fig. 2. Crystal structure of [Ni(HDSH-2H)(EtOH)(H2O)].
Fig. 3. Crystal structure of [Cu(HDSH-2H)].
Table 4
IR spectral data of HDSH and its complexes.
Compound
m
(OH)
m
(NH)
m
(C@O)
m
(C@N)
m
(C@Nb)
d(OH)
m
(NAN)
m
(MAN)
HDSH
3290
3038
–
–
–
3068
–
1644
–
1635
1641
–
–
1644
–
1625
1610
1608
1605
1581
1604
1606
1603s
1596
1610
–
–
1368
1378
–
1362
–
1375
1357
1376s
1376vs
––
1069
1055
1075
1094
1107
1088
1066
1086
1073
1060
–
433
426
[Co(HDSH-2H)(H2O)2]
[Cd2(HDSH-4H)(H2O)4]
[Hg(HDSH-2H)]
[Zn(HDSH-2H)(H2O)2]
[Ni(HDSH-2H)(EtOH)(H2O)]
[Cd2(HDSH-2H)Cl2(H2O)4]
[Cu(HDSH-2H)]
3280
3554a
3283
–
–
1536
1578
1540
3450a
3313br
3554a, 3242
3326br
–
422
416
408
406
–
–
[Cu(HDSH-H)2]
[Pd2(HDSH-4H)(H2O)4]
3500a
–
1591
427
a
Coordinated water.
New azomethine group.
b

312
B. Jeragh, A.A. El-Asmy / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 129 (2014) 307–313
Table 5
Table 7
1H NMR spectra of HDSH and its complexes.
Thermal decomposition stages of HDSH and its complexes.
Compound
OH
NH
CHph
CH2
–
CH3
Compound
M.F.
Average temp.,
(°C)
Species removal (%)
HDSH
12.490 11.249 7.968–7.020
3.184
[Cd2(HDSH-4H)(H2O)4]
[Hg(HDSH-2H)]
[Zn(HDSH-2H)(H2O)2]
–
–
–
–
7.945–7.041 1.990 3.362
7.952–7.453 1.360 2.046
7.954–7.012 1.078 2.139
HDSH
384.44
678.16
245
87.72
Residue 1.52%
11.831
13.825
11.473
[Cd2(HDSH-4H)(H2O)4]
302
641
11.33
63.67
Residue 10.75%
[Cd2(HDSH-2H)Cl2(H2O)4] 11.466
[Pd2(HDSH-4H)(H2O)4]
–
–
7.864–7.005 1.070 2.037
7.900–7.057 1.921 3.348
–
[Hg(HDSH-2H)]
583.23
275
65.17
Residue 34.83% (Hg)
[Zn(HDSH-2H)(H2O)2]
485.824 319
47.86
Residue 14.88% (Zn)
p
?
pꢄ and n ? pꢄ bands at 39,215 and 33,000 cmꢂ1 for the amide
groups [14]. A small change is observed on the spectra of its com-
plexes. The bands at 29,155–21,550 cmꢂ1 in the spectra of the
complexes (Table 4) may be due to LMCT from N and O donors.
The electronic spectrum of [Co(HDSH-2H)(H2O)2] showed
[Ni(HDSH-
2H)(EtOH)(H2O)]
505.25
111
290
11.95
38.84
Residue 13.48%
(NiO)
bands at 16,745 and 19,540 cmꢂ1 assigned to 4T1g ? 4A2g
(m2)
[Cd2(HDSH-
2H)Cl2(H2O)4]
748.20
302
641
11.33
63.67
Residue 10.75%
and 4T1g ? 4T1g(P) (
[15]. The eff value is 4.83 BM which lies inside the range reported
m3) characteristic for an octahedral geometry
l
[Cu(HDSH-2H)]
445.968 284
53.09
for complexes having the proposed geometry (4.7–5.2 BM). The
previously reported Co(II) complexes with the same ligand [9] have
a binuclear moiety containing Cl or acetate anion. The ligand field
parameters (B, b, 10Dq) are calculated and their values are
869 cmꢂ1, 0.895 and 869 cmꢂ1. It is worthy to note that the value
of 10Dq ordered the strength of the ligand, based on the crystal
field splitting energy, in the series of moderate ligands. Consider-
able reduction in the B value from 971 in the free Co(II) to
869 cmꢂ1 in the complex and b from unity to 0.895 indicate more
ionic character of LAM bonds.
Residue 31.07%
[Pd2(HDSH-4H)(H2O)4]
665.283 235
288
23.00
14.88
Residue 45.35%
(2PdO2)
presented in Table 7. [Ni(HDSH-2H)(EtOH)(H2O)] is taken as an
example.
The steady part of the thermogram of [Ni(HDSH-2H)(EtOH)
(H2O)] till 111 °C indicates the absence of any solvent outside the
sphere. The 1st decomposition step at mid-point 111 °C is due to
the removal of C2H5OH + H2O (% Found 11.95; Calcd. 12.67). The
2nd step indicates the decomposition of part of Ni(HDSH-2H) (%
Found 38.84). NiO is the stable residue at 800 °C (% Found 13.48;
Calcd. 14.85). The residual parts in the Zn(II) and Hg(II) complexes
are the metal atoms (Table 6). In the Pd(II) complex, the residue is
PdO2.
The magnetic moment of [Ni(HDSH-2H)(EtOH)(H2O)] is 3.23
3
BM expected for octahedral structure with A2g ground term
[16]. Its electronic spectrum shows broad band at 13,245 cmꢂ1 as-
signed to the 3A2g ? 3T1g (F) (
m2) transition [17]. The value of B
(656 cmꢂ1) and Dq (1054 cmꢂ1) are used to calculate b and m1
,
3A2g ? 3T2g (F), to be 0.62 and 10,540 cmꢂ1, respectively [18]. The
previous complexes have tetrahedral and octahedral geometries;
the octahedral one was formed in the keto-form [9].
The electronic spectra of [Cu(HDSH-2H)] and [Cu(HDSH-H)2]
exhibit bands at 15,410 and 21,050 cmꢂ1, respectively, assigned
to 2T2g ? 2Eg. The band position with magnetic moments of 1.98
ESR spectra
The room temperature solid state ESR spectra of the copper
complexes exhibit axially symmetric g-tensor parameters with
g|| > g\ > 2.0023 indicating that the copper site has a d2x ꢂ y2 ground
state [21]. The ESR spectra of [Cu(HDSH-2H)] and [Cu(HDSH-H)2]
are similar to the ESR spectra of the reported mononuclear Cu2+
complexes [22]. The spectra of the two complexes exhibit a single
line centered at g|| = 2.250; 2.226 and g\ = 2.070; 2.059, respec-
tively, attributable to dipolar broadening and enhanced spin lattice
relaxation. This line is probably due to insufficient spin-exchange
narrowing toward the coalescence of four copper hyperfine lines
to a single line. Note that, the same kind of powder ESR line shapes
have been observed for many tetrahedral or square-planar Cu2+
and 1.64 BM are consistent with
a square-planar geometry
[19,20]. The lower value in [Cu(HDSH-H)2] may be due to little
effect of the diamagnetic ligands on the magnetic interaction due
to the presence of two ligand molecules.
The spectrum of Pt(II) complex showed bands at 13,040 and
12,675 cmꢂ1 attributed to 1A1g ? 1Eg transition.
Thermal studies
The thermogravimetric data considering the decomposition
temperature and the weight losses for most complexes are
Table 6
Magnetic moments and electronic spectral bands of HDSH and its metal complexes.
Compound
leff (BM)
Intraligand bands (nm)
d–d Bands, (nm)
Proposed structure
HDSH
–
39,215, 33,000
–
[Co(HDSH-2H)(H2O)2]
[Cd2(HDSH-4H)(H2O)4]
[Hg(HDSH-2H)]
[Zn(HDSH-2H)(H2O)2]
[Ni(HDSH-2H)(EtOH)(H2O)]
[Cd2(HDSH-2H)Cl2(H2O)4]
[Cu(HDSH-2H)]
4.83
–
–
–
3.23
–
37,760, 33,365, 31,155
38,910, 33,000
16,745, 19,540
Octahedral
Tetrahedral
Tetrahedral
Octahedral
Octahedral
–
Square-planar
Square-planar
Square-planar
39,060, 33,110, 29,155
36,495, 34,480, 32,050
38,760, 35,970, 34,365, 32,155
39,060, 33,000, 21,550
27,400, 26,110
–
17,300, 13,245
–
15,410
21,050
13,040, 12,675
1.98
1.64
[Cu(HDSH-H)2]
[Pd2(HDSH-4H)(H2O)4]
39,215, 34,840, 32,785, 27,400
38,760

B. Jeragh, A.A. El-Asmy / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 129 (2014) 307–313
313
complexes with a strong intra-nuclear spin-exchange interaction.
In axial symmetry, the g-values are related by the expression,
G=(g||ꢂ2)/(g\ꢂ2) = 4. According to Hathaway [23], the calculated
G values for [Cu(HDSH-2H)] and [Cu(HDSH-H)2] are 3.57 and
3.83 suggesting copper–copper exchange interactions. The molec-
can be obtained free of charge at www.ccdc.cam.ac.uk/conts/
retrieving.html.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.saa.2014.02.195.
ular orbital coefficients
using the reported equations [24] and found to be 0.94 and 0.86,
respectively. The low value of b2 than 2 indicates that the in-plane
-bonding is less covalent [25].
a
2 and b2 for [Cu(HDSH-2H)] are calculated
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Acknowledgment
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CCDC reference numbers 842111 and 840137 contain the
supplementary crystallographic data for this article. These data