Polymer complexes. LIII. Supramolecular coordination modes and structural of novel sulphadrug complexes

Article abstract of DOI:10.1016/j.saa.2010.08.006

Novel polymer complexes of copper(II), palladium(II), platinum(II) and cadmium(II) containing homopolymer [4-acrylamido benzene sulphonyl guanidine; (HL)] and various anions (SO₄^2-, CH₃COO ^-, NO₃

Full text of DOI:10.1016/j.saa.2010.08.006

Spectrochimica Acta Part A 77 (2010) 795–801
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Polymer complexes. LIII. Supramolecular coordination modes and structural of
novel sulphadrug complexes
M.A. Diab, A.Z. El-Sonbati∗, R.H. Mohamed1
Chemistry Department, Faculty of Science (Demiatta), Mansoura University, New Demiatta, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
Novel polymer complexes of copper(II), palladium(II), platinum(II) and cadmium(II) containing
homopolymer [4-acrylamido benzene sulphonyl guanidine; (HL)] and various anions (SO42−, CH3COO−,
NO3−, Br− or Cl−) have been designed and carried out. Their structures were investigated by elemen-
tal analyses, spectral (IR, UV–vis, 1H NMR and ESR) and magnetic moments. The modes of interactions
Received 17 March 2010
Received in revised form 28 July 2010
Accepted 3 August 2010
between the ligand and the metals were discussed, where oxygen (of O
S O group) and nitrogen atom
Keywords:
[of imino nitrogen (NH/N) of the guanidine group] are involved in chelation. The homopolymer shows
two types of coordination behaviour. In mononuclear polymer complexes 4 and 6–10, it acts as a neutral
bidentate ligand chelated through the NH and O atoms, whereas in the polymer complexes 1–3, 5 and
11, monobasic bidentate ligand is coordinated through the –N and –O atoms. The poly-chelates are of
1:1/1:2 (metal–homopolymer) stoichiometry and exhibit four coordination. On the basis of electronic
spectral data and magnetic susceptibility measurement square planar geometry has been proposed. The
ESR spectral data provided information about their structure on the basis Hamiltonian parameters and
degree of covalency. From the electron paramagnetic resonance and spectral data, the orbital reduction
factors were calculated.
Homopolymer sulphadrug
Supramolecular polymer complexes
Spectral studies
© 2010 Elsevier B.V. All rights reserved.
1. Introduction
The field of polymer chemistry is developing very rapidly
because of its applications and importance in the area of coordina-
Substantial work has been done by Diab and El-Sonbati and our
co-workers [1–8] on poly-chelates derived from hydroxy-ketone,
acryloyl chloride and various aliphatic and aromatic amines. How-
ever, no attempt seems to have been made to study the synthesis,
characterization, coordination chemistry, thermal stability and bio-
logical function of some transition metal polymeric complexes
for which structural information was obtained by spectrochemi-
cal and magneticochemical means. The studies of Cu(II) complexes
have been widely explored for the versatility of their coordina-
tion geometries, exquisite color, technical application dependent
molecular structures, spectroscopic properties and their biochem-
ical significance. Octahedral Cu(II) complexes of ligands containing
mixed electron donors have been studied extensively; due to their
potential applications as molecular materials [9–13]. The chem-
istry of sulphadrug derivatives has attention because of their
interesting structural properties and applications in diverse areas
[14–17].
tion chemistry [8–17]. The stability of polymeric metals complexes
depends upon a number of factors, including the number and types
of donor atoms present in the homopolymer and their relative posi-
tions with the homopolymer skeleton, as well as the number and
the size of the chelate rings formed on complexation [1–15]. Coor-
dination polymers are useful as engineering materials and find an
important place in material chemistry [18]. Polymer complexes of
lanthanides and or transition metal are currently attracting much
attention towards tumor [19] and DNA targeting [20].
As
a part of our ongoing work [1–15] in the area of
supramolecular assembly of polymer complexes based on aro-
matic and/or aliphatic amine sulphadrugs, we report herein
the synthesis, characterization, structure of HL (Fig. 1) and
properties of copper supramolecular polymer complexes
of the general formula [CuHL·O2SO2]n, [CuL·X]n (X = OAc,
O2NO) and [CuL·Cl·OH2]n. The most probable coordination,
semi-coordination and hydrogen bonds related to inclu-
sion phenomena, guest exchange and molecular based
nickel will be discussed more in detail. Recently, El-Sonbati
[1,2,6,13,14] published a paper on rare earth/d-block ions with
sulphadiazineazo-3-phenyl-2-thioxo-4-thiazolidinone [HL1], 5-
sulphamethazineazo-3-phenyl-2-thioxo-4-thiazolidinone [HL2],
5-sulphamethoxoleazo-3-phenyl-2-thioxo-4-thiazolidinone
∗
Corresponding author. Tel.: +20 60081581; fax: +20 502254000.
E-mail address: elsonbatisch@yahoo.com (A.Z. El-Sonbati).
1
1Abstracted from his Ph.D.
1386-1425/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2010.08.006

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M.A. Diab et al. / Spectrochimica Acta Part A 77 (2010) 795–801
2.3. Preparation of the polymer complexes
2.3.1. Method A: copper(II) salts, polymer complexes 1–4 and
cadmium(II) chloride, polymer complex 5
All the metal polymer complexes in this work were pre-
pared using 1:1 metal:ligand molar ratio. Polymer complexes were
prepared by mixing HL monomer (0.01 mol) in 20 ml dimethyl-
formamide (DMF) and the copper(II) salts and/or Cd(II) chloride
(0.01 mol) in 20 ml DMF as
a
solvent, and 0.1% (w/v) 2,2ꢀ-
azobisisobutyronitrile (AIBN) as initiator. The mixture was boiled
under reflux for 6 h. The hot solution was precipitated by adding to
a large excess of distilled water, containing dilute hydrochloric acid,
to remove the metal salts that were incorporated into the polymer
complexes. The polymer complexes (1–5, see Table 1) were filtered,
washed with water, and dried in a vacuum oven at 40 ◦C for several
days to yield 65–75% of colored crystals.
2.3.2. Method B: palladium(II) salts polymer complexes 6–9
Solution of PdX2 (X = Cl or Br; 0.01 mol); HL (0.01 or 0.02 mol)
and 0.1 (w/v) AIBN (2,2ꢀ-azobisisobutyronitrile) as initiator in
MeOH–DMF (3:2, v/v) containing a few drops of concentrated HCl
were mixed and stirred for 3 h at room temperature, polymer com-
plexes precipitated immediately; then they were reflux for ∼2.5 h
to complete the reaction; these were poured into a large excess of
distilled H2O containing dilute HCl, to remove the metal salt incor-
porated into the polymer complexes. The products were filtered,
washed with water, methanol and finally, with ether.
Fig. 1. The preparation and structure of the homopolymer (HL).
2.3.3. Method C: platinum chloride polymer complex 10
The salt K2[PtCl4] was dissolved in water–ethanol (1:1, v/v) and
HL in a 0.1N HCl; the pH of both solutions was acidic. The two solu-
tions were mixed and stirred at room temperature for 13 h in the
presence of 0.1 (w/v) AIBN (2,2ꢀ-azobisisobutyronitrile) as initiator.
The obtained precipitate was filtered off and washed with small
portions of water, EtOH and Et2O.
[HL3], 5-sulphacetamideazo-3-phenyl-2-thioxo-4-thiazolidinone
[HL4], 5-sulphaguanidineazo-3-phenyl-2-thioxo-4-thiazolidinone
[HL5].
Recently in our laboratory, numerous polymer complexes
and/or complexes of rhodanine sulphadrug and its derivatives have
been reported [1–15]. In this paper, we report the synthesis and
spectroscopic characterization of copper(II) polymer complexes
with 4-(acrylamido) benzenesulphonyl guanidine (HL).
2.3.4. Method D: palladium polymer complex 11
To a suspension of compounds 7 + 8 in 50 ml of DMF–ethanol
(1:1, v/v) was added an aqueous solution (25 ml) of potassium
hydroxide (0.4 g). The mixture became clear and yellowish powder
was precipitated. The product was washed with water and Et2O
after filtrated.
2. Experimental
Experimental techniques were as described previously [3,7–12].
Homopolymer was prepared by the method described by Diab, El-
Sonbati and co-workers [3,7–12].
2.4. Measurements
C, H, and N microanalyses were carried out at the Cairo Uni-
versity Analytical Center, Egypt. The metal content in the polymer
complexes was estimated by standard methods [7–10]. The 1H
NMR spectrum was obtained with a Jeol FX90 Fourier transform
spectrometer with DMSO-d6 as the solvent and TMS as an internal
reference. Infrared spectra were recorded using Perkin-Elmer 1340
spectrophotometer. Ultraviolet–visible (UV–vis) spectra of the
polymer were recorded in nuzol solution using a Unicam SP 8800
spectrophotometer. The magnetic moment of the prepared solid
complexes was determined at room temperature using the Gouy’s
method. Mercury(II) (tetrathiocyanato)cobalt(II) [Hg{Co(SCN)4}],
was used for the calibration of the Gouy’s tubes. Diamagnetic
corrections were calculated from the values given by Selwood
[22] and Pascal’s constants. Magnetic moments were calculated
2.1. Reagents
Sulphaguanidine was bought from Aldrich and used without
further purification. Acryloylchloride (Aldrich) was used with-
out purification. 2,2ꢀ-Azobisisobutyronitrile (AIBN) was purified by
fractional crystallization from EtOH [21].
HL monomer was prepared according to the literature methods
[3,7–12]. The IR spectrum of the monomer showed the presence of
a NH absorption band at 3165 cm−1. Anal. Found: C, 44.8; H, 4.0; N,
15.9; S, 11.5%. Calcd. For HL(C10H11N3SO4): C, 44.6; H, 4.1; N, 15.6;
S, 11.9%. 1H NMR (300 MHz, DMSO-d6): ı(ppm) 10.22 (CONH); 5.80,
5.50 (CH2 C).
ꢀ
ꢁ
1/2. EPR measurements of
coor.
using the equation, ꢀeff. = 2.84 Tꢁ
M
2.2. Polymerization
powdered samples were recorded at room temperature (Tanta Uni-
versity, Egypt) using an X-band spectrometer utilizing a 100 kHz
magnetic field modulation with diphenylpicrylhydrazyle (DPPH) as
a reference material. TG measurements were made using a Du Pont
950 thermobalance. Ten milligram samples were heated at a rate of
Monomer HL was polymerized by the method described by Diab,
El-Sonbati and co-workers [3,7–12]. The homopolymer has been
characterized by IR, 1H NMR.

M.A. Diab et al. / Spectrochimica Acta Part A 77 (2010) 795–801
797
Table 1
Analytical data of the polymer complexesa (for molecular structure see Fig. 1)b.
Complexc
No.
Method of preparationd
Experimental (Calcd.) %
C
H
N
(S/Cl)e
Molar ratio
[Cu(L)Cl·OH2]n
A
A
A
A
A
B
B
B
B
C
D
31.5
(31.3)
30.7
(30.6)
37.2
(37.0)
28.0
(28.1)
27.5
(27.7)
27.0
(26.8)
22.5
(22.4)
33.7
(33.6)
29.9
(30.1)
22.5
(22.2)
37.5
(37.4)
3.3
(3.4)
3.0
(2.8)
3.6
(3.6)
2.8
(3.0)
3.0
(3.0)
2.7
(2.7)
2.3
(2.2)
3.4
(3.3)
3.0
(2.9)
2.3
(2.1)
3.5
(3.3)
14.3
(14.6)
18.1
(17.8)
14.7
(14.4)
13.1
(13.4)
13.2
(12.9)
12.6
(12.9)
10.5
(10.8)
15.7
(15.5)
14.0
(14.3)
10.5
(10.8)
17.5
(17.2)
8.5/9.6
(8.3)/9.3
8.0
(8.2)
8.4
(8.2)
15.0
(15.3)
7.7/8.0
(7.4)/8.2
7.2
(7.4)
6.0
(6.2)
9.0
(8.8)
8.0
(8.4)
6.0
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:2
1:2
1:1
1:2
1
[Cu(L)O2NO]n
2
[Cu(L)OAc]n
3
[Cu(HL) (O2SO2)]n
4
[Cd(L)Cl·OH2]n
5
[Pd(HL)Cl2]n
6
[Pd(HL)Br2]n
7
{[Pd(HL)2]Cl2}n
8
{[Pd(HL)2]Br2}n
9
[Pt(HL)Cl2]n
10
[Pd(L)2]n
11
(6.2)
10.0
(9.7)
a
Microanalytical data as well as metal estimations are in good agreement with the stoichiometry of the proposed complexes.
The excellent agreement between calculated and experimental data supports the assignment suggested in the present work.
HL are the ligand as given in Fig. 1 and L is the anion; air stable; no-hygroscopic; insoluble in water; soluble in coordinating solvents such as DMF and DMSO.
See text.
Estimated gravimetrically.
b
c
d
e
10 ◦C/min in a dynamic nitrogen atmosphere (70 ml/min); the sam-
ple holder was boat-shaped, 10 mm × 5 mm × 2.5 mm deep; the
temperature measuring thermocouple was placed within 1 mm of
the holder. The halogen content was determined by combustion
of the solid complex (30 mg) in an oxygen flask in the presence
of a KOH–H2O2 mixture. The halide content was then determined
by titration with a standard Hg(NO3)2 solution using diphenyl car-
bazone as an indicator.
–C NH groups. The relative down field appearance of the third peak
(ı = 7.48 ppm) may be due to the intramolecular hydrogen bond-
ing between NH and S O groups [15]. The broad medium signal
centered at ı = 5.45 ppm which could be assigned to the NH2 pro-
tons. These signals disappeared on repeating the measurements in
the presence of D2O. The 1H NMR spectrum of the ligand showed
characteristic protons, which are listed in Table 2.
The NMR spectrum of monomer (HL) showed the expected
peaks and pattern of the vinyl group (CH2 CH), i.e. ı(DMSO-d6)
6.25 ppm (dd, J = 17, 11 Hz) for the vinyl CH proton and proton ı
5.12 ppm (AM part of AMX system dd, J = 17, 1 Hz) for the vinyl CH2
protons, respectively. These peaks disappeared on polymerization
3. Results and discussion
3.1. Characterization of the uncomplexed
HL was prepared by the amidation reaction of acryloyl chloride
with sulpha guanidine [3,7–12]. The monomer HL was charac-
terized as in Section 2. The monomer was then polymerized
as in Section 2. The monomer was then polymerized by radi-
cal polymerization initiated by 2,2ꢀ-azobisisobutyronitrile (AIBN).
The homopolymer has been characterized by various techniques
[7–12].
Herein we demonstrate the coordination mode of HL to gener-
ate Cu(II) polymer complexes. As expected these complexes are ESR
active due to the presence of an unpaired electron. The Cu(II) com-
plexes generally exhibit room temperature magnetic susceptibility
as expected for an isolated d9 transition metal center.
Table 2
Characteristic 1H NMR spectra for HL, Cd(II) complex (ppm vs. TMS)a.
Compoundb
HL
Chemical shift ı(ppm)
Assignment
7.44
11.30
5.45
7.26
7.48
7.22
11.15
4.48
7.17
–
d, 4H, ArH’s
d, 1H, CONH
br, 2H, –C NHNH2
br, 1H, –SO2NH
s, 1H, –C NH
d, 4H, ArH’s
d, 1H, CONH
br, 2H, –C NHNH2
br, 1H, –SO2NH
s, 1H, –C NH
5
3.54
7.54
11.18
4.82
7.12
7.30
7.65
11.22
4.68
7.07
7.25
br, coordinated H2O proton
d, 4H, ArH’s
d, 1H, CONH
br, 2H, –C NHNH2
br, 1H, –SO2NH
s, 1H, –C NH
d, 4H, ArH’s
d, 1H, CONH
br, 2H, –C NHNH2
br, 1H, –SO2NH
s, 2H, –C NH
6
8
3.1.1. The ligand
HL used in this study is elucidated by different tools as, the
elemental analysis, which used to propose the HL formula and
IR spectrum supported this. 1H NMR spectrum is the final con-
firming tool for the ligand structure and displayed a peaks for
C
NHNH2, SO2NH and –C NH. 1H NMR spectrum of HL [ı(DMSO-
d6)] is the final confirming tool for the ligand structure and
displayed a singlet peak at ı = 7.44 ppm by integration assigned
to 4H referring to the phenyl group. Also, the three singlet peaks
at 11.3, 7.26 and 7.48 ppm each peak by integration assigned to
the three hydrogen atoms aggregated from CONH, SO2NH and
a
The excellent agreement experimental data supports the assignment suggested
in the present work.
b
See footnote in Table 1.

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M.A. Diab et al. / Spectrochimica Acta Part A 77 (2010) 795–801
while a triplet at ı 1.86 ppm (t, J = 7 Hz) and a doublet at ı 1.80 ppm
(d, J = 7 Hz) appeared. This indicates that the polymerization of HL
monomer occurs on the vinyl group [7]. It is worth noting that the
rest of the proton spectrum of the monomer and polymer remains
almost without change.
presence of coordinated water molecules. In case of 8, the signal
characteristic for –C NH(NH2) group shifted to lower frequency
due to the coordination via NH atom.
IR spectra of the polymer complexes suggest that the formation
of a stable six-membered ring system with the central Cu(II)/Cd(II)
ion having O–NH/O–N donor function taking one of oxygen of
3.2. Characterization of polymer complexes
O S O and nitrogen of the –C NH(NH2) and the imino nitro-
gen (NH/N) of the guanidine residue as bonding sites is the most
probable proposition; this substantiated through the present IR
spectral studies recorded down to 200 cm−1. The IR spectrum of the
homopolymer showed three medium broad bands at 3165, 3280
and 3440 cm−1 which consist of overlapping stretching vibration
assigned to ꢂs(N–H) and ꢂas(NH and NH2 groups). The bandwidth
further indicates that the NH2 group is involved in intramolecu-
lar hydrogen bonding [24]. Also, the IR spectrum of uncomplexed
polymer (HL) shows absorption bands at 3350 and 1630 cm−1 due
to NH and CO groups, respectively. These bands disappear when
the homopolymer is dissolved in DMSO and four absorption bands
have been observed at 1600, 1540, 1470 and 1415 cm−1 which
are attributed to ꢂasym + sym(C C) and ꢂ(C N) vibrations. The SO2
group modes of the HL appear as a bands at 1315 cm−1 (ꢂasym(SO2))
and 1036 cm−1 (ꢂsym(SO2)), respectively.
3.2.1. Metal polymeric complexes
The HL used in this study is elucidated by different tools as, the
elemental analysis, which used to propose the HL formula, IR and 1H
NMR supported this. All the isolated polymer complexes are air sta-
ble for extended periods and remarkably soluble in DMSO and DMF.
The molar conductivities in DMF solution indicate that the polymer
complexes are in the range expected for non-electrolytes [23]. This
can be account for by the satisfaction of the bi-valency of the metal
by the chloride, nitrate, acetate and sulphate. This implies the coor-
dination of the anions to the metal ion centers. The analytical data
of the isolated polymer complexes are listed in Table 1. Further,
confirmation of the proposed structures of the chelates of HL with
metal salts was done by using different physico-chemical meth-
ods shown below. The formation of these complexes may proposed
according to the following equation:
In the polymer complexes, the asymmetric and symmetric
modes are shifted to higher frequencies, at 1330 and 1085 cm−1
[25]. Also, the stretching vibration mode characteristic for ꢂ(NH)
of –C (NH) (NH2) moiety at 3175 cm−1 in HL was shifted to higher
frequencies (∼3195–3215 cm−1) upon coordination to the transi-
tion metals [25] via deprotonated NH group, except compound 1.
The ꢂ(C N) stretching bands of the guanidine part of the ligand
appearing around 1645 cm−1 [26] has been found to experience a
negative shift of ≈8 cm−1 pointing to the probable participation of
the imino nitrogen/nitrogen of the guanidine moiety of the ligand
in complexes. New bands were found in the spectra of the polymer
complexes in the regions 450–470 and 495–520 cm−1 which were
assigned to ꢂ(M–N) and (M–O) stretching vibrations, respectively
[1–6,34]. These stretches were not present in the spectra of the lig-
and. The appearance of band in compounds 1 and 5 at ∼800 and
∼760 cm−1 attributed to coordinated water molecule. The unco-
ordinated homopolymer exhibits strong and weak bands at 3350,
3372, 1630, 410 and 390 cm−1, respectively. These are assigned to
the ꢂ(NH), ꢂ(NH), of the sulphonamide group and C–C out-of-plane
vibration [27].
CuSO4 + HL → [Cu(HL)(SO4)]n
(1)
(2)
(3)
CuX2 + HL → [Cu(L)X]n
X = OAcorNO3
M = Cu(II) or Cd(II)
MCl2 + HL → [M(L)Cl·OH2]n
MX2 + HL → {[M(HL)nꢀX2]Y2}n
M
=
Pd(II), X = Cl and/or Br; Y = nil; nꢀ = 1
(4)
(5)
MX2 + HL → {[M(HL)nꢀX2]Y2}n
M
=
Pd(II), X = nil and/or Br; Y = Cl; nꢀ = 2
MX2 + HL → {[M(HL)nꢀX2]Y2}n
M
=
Pt(II), X = Cl; Y = nil; nꢀ = 1
(6)
(7)
PdCl2 + HL → [Pd(L)2]n
In order to elucidate the type of homopolymer coordination and
related geometry in the polymer complexes, NMR, IR and spectra
were recorded.
3.2.2. Bands due to anions
Additional, the IR spectra of the polymer complexes show the
bands due to coordinated anions. Due to the acetate complex 2
shows the bands at 1430 and 1340 cm−1 corresponding to ꢂas(OAc)
and ꢂs(OAc) stretching vibrations, respectively. The separation of
these two vibrations (90 cm−1) indicates the bidentate coordina-
tion of acetate anion [28]. In the spectrum of polymer complex 3,
three additional bands which are not present in the spectrum of
free ligand, were observed. Of these, the band around 1028 cm−1
is assigned to the ꢂ2 mode of the nitrate group. The bands in 1463
and 1258 cm−1, are the two split bands of ꢂ4 and ꢂ1, respectively,
of the coordinated nitrate group. The magnitude of ꢂ4–ꢂ1 is about
200 cm−1 in the complex 3, which indicates that the nitrate group
is coordinated to the cupper(II) ion in a bidentate fashion [28]. The
sulphato complex 4 shows the four bands at 1211, 1131, 1028, and
965 cm−1 due to ꢂ3 and ꢂ1 stretching vibrations of sulphate anion
which indicates that the sulphate anion coordinates in bridging
bidentate manner [29]. The chloro complexes 1 and 5 shows the
band at ≈332 cm−1 due to ꢂ(M–Cl) and also display bands due to
coordinated water molecules. The bands in the range of 645–852
and 612–635 cm−1 appeared in the spectra of these polymer com-
plexes which may be assigned to pr(H2O) and ␳w(H2O) [27].
Copper acetate, copper nitrate, palladium chloride and cadmium
chloride under the same condition, give a polymer complexes con-
taining the homopolymer as a monoanion, having lost one proton
from C NH group while copper sulphate, palladium chloride, plat-
inum chloride and palladium bromide form polymer complexes in
which the homopolymer is neutral. This occurs in the presence of
the sulphate ion as proton acceptor. This indicates that the polymer
complexes composition is dependent on the nature and strength of
the metal–homopolymer bond.
The 1H NMR spectra of HL and all the diamagnetic polymer com-
plexes showed the same characteristic proton signals for the ligand
(HL). The chemical shifts of the different types of protons of HL and
diamagnetic 5, 6 and 8 polymer complex are listed in Table 2. The
signal characteristic for –C (NH) group in polymer complexes 5
and 6 disappeared in the spectra of the isolated polymeric com-
plexes indicating coordination via deprotonated NH atom. Also, the
signal characteristic for NH2 group shifted to lower frequencies due
to the complexation. Also, the 1H NMR spectrum of the complex
5 showed a broad signal at 3.54 ppm, which is attributed to the

M.A. Diab et al. / Spectrochimica Acta Part A 77 (2010) 795–801
799
Table 3
Magnetic moment and electronic spectral data of the Cu(II) polymer complexes (for molecular structures see Fig. 2).
Speciesa
ꢀeff. (B.M.)b
Band position (cm−1
)
Assignments
Geometry
Ref.
1
1.90
10,150, 18,620, 27,368, 38,595
dx2−y2 → dz2 (ꢂ1)
→dxy (ꢂ2)
→dxy, dyz(ꢂ3)
CT
Square planar
[32,42]
2
3
4
1.85
1.92
1.82
10,530, 18,620, 26,170, 38,015
10,330, 18,618, 26,310, 37,585
10,512, 18,618, 27,240, 36,300
-do-
-do-
-do-
[32,42]
[32,42]
[32,42]
a
See footnote in Table 1.
The order of ꢀeff. is 3 > 1 > 2 > 4. Per metal. Measured at room temperature.
b
The far IR data of the polymer complexes give an insight into
The ESR spectra of the copper polymer complexes have been
recorded at room temperature (Table 4) which exhibit an axi-
the structure and bonding in the solid state. The ꢂ(M–Cl)L (M = Pd,
Pt) modes are assigned to strong intensity bands in the region
350–340 cm−1 for 6 and 10. They shift to the 240–225 cm−1 region
in 7. The appearance of these bands is consistent with the formu-
lation [M(HL)X2]. The presence of two ꢂ(M–X)L vibrations in each
far IR spectrum confirms the cis-structures of the square planar
complexes 6, 7 and 10 [30]. In polymer complexes of stoichiome-
try [Pd(HL)X2], the monomer coordinates to the metal ion via the
nitrogen atom [of imino nitrogen (NH) of guanidine group] and the
ally symmetric g-tensor parameters with g > g > ge(2.0023), was
||
⊥
observed for all the complexes, corresponding to the presence of
unpaired electron most likely reside in the dx2−y2 (or less likely a
dxy) ground state [33] which is consistent with the proposed planar
stereochemistry [34]. The g values are given in Table 4. The devi-
ation of g value from the free electron value (2.0023) may be due
to angular momentum contribution in the polymer complexes. In
all the polymer complexes, the g values are less than 2.3, which
||
oxygen [of O
S
O group]. This is further supported by the appear-
shows that the complexes are largely covalent. Further, the val-
ues are consistent with Cu–N and Cu–O bonded copper complexes.
ance of IR active bands at 280–285 [ꢂ(Pd–O)] and 475–485 cm−1
[ꢂ(Pd–N)] vibrational modes [30].
The g values are found in the order 4 > 1 ≈ 3 > 2. On the basis of
||
these values, it is clear that compound 2 is a strong ligand and
create strong ligand field. Our results are in agreement with the
respective positions of the anions as given in the spectrochemical
series [32]. The average g values (giso) are calculated, and give val-
ues in the range 2.086–2.112. The ESR data are reported in Table 4.
The giso values for the polymer complexes studied follow the order
4 > 1 > 3 > 2.
3.3. Magnetochemical and ligand field spectral studies of Cu2+
polymer complexes
The electronic spectra of the polymer complexes (Table 3)
are in good agreement with other spectra and the literatures
[4,5,10]. The room temperature magnetic moments of copper(II)
polymer complexes fail in range 1.82–1.92 B.M. which are typ-
Kivelson and Neiman [35] have shown that g is a parame-
||
ter sensitive function for indicate covalence. The g values for
ical for square planar (D4h) and tetrahedrally distorted (D2h
)
||
all the Cu(II) polymer complexes are less than 2.3 is an indica-
tion of significant covalent bonding in these polymer complexes
(Cu–L). In axial symmetry the g values are related to the G-factor by
mononuclear copper(II) complexes and did not indicate any anti-
ferromagnetic coupling of spines at this temperature. The relatively
higher 1.92 B.M. value observed for 3, seem to suggest the rel-
atively high tetrahedral distortion from square planar geometry
for these complexes than others in polycrystalline state. On the
other hand, the B.M. data for 1, 2, and 4 fall in the 1.82–1.90 B.M.
the expression, G = g − 2.0023/g⊥ − 2.0023 = 4, which measures the
||
exchange interaction between copper centers in the solid. Accord-
ing to Hathaway [36], if the value of G is greater than 4, the exchange
interaction between copper(II) centers in the solid state is neg-
ligible, whereas when it is less than 4, a considerable exchange
interaction exists in the solid complex. The calculated G values for
copper complexes are greater than 4, suggesting the absence of
exchange coupling between copper(II) centers in the solid state
[37]. The G values follow the order 3 > 2 > 4 > 1. This is consistent
with the order of the strength of metal–anion interactions. Our
results are also in agreement with the respective positions of these
anions as given in the spectrochemical series [38].
range and are well consistent with a square planar geometry (D4h
)
around the copper centers (Table 3). The electronic spectra of the
polymer complexes show the absorption bands corresponding to
2
2
2
and [2B1g → Eg](ꢃ1), [2B1g → B2g](ꢃ2) and [2B1g → A1g], tran-
sitions, respectively [31]. The polymer complexes also display the
high-energy charge transfer. These transition commensurate the
square planar geometry and D4h symmetry for the complexes [32]
(Table 3).
3.4. Electron spin resonance
3.4.1. Bonding parameters and orbital reduction parameters
To obtain further information about the stereochemistry and the
site of the ligand bonding and to determine the magnetic interac-
tion in the metal polymer complexes, ESR spectra of the complexes
were recorded in the solid state. The spin Hamiltonian parameters
of the complexes were calculated and summarized in Table 4.
The ESR parameters g , g , g , A and A and the energies of
||
⊥
||
⊥
iso
the d–d transition are used to calculate the bonding parameters
2
˛
and ˇ2, which are the measure of covalency of the in-plan ␴-
bonding and covalency of the in-plane ␲-bonding and out-of-plane
Table 4
ESR parameters of complexes.
a
b
b
2
Complexa
g
||
g
⊥
giso
G
A
||
A
⊥
Aiso
˛
1
2
3
4
2.219
2.180
2.218
2.225
2.054
2.039
2.043
2.056
2.11
2.09
2.10
2.11
4.17
4.84
5.30
4.24
117.8
113.6
99.3
66.18
57.26
62.03
65.71
83.39
76.04
74.45
82.11
0.61
0.55
0.61
0.61
114.9
a
See footnote in Table 1.
Fig. 2. Structure of polymer complexes. (1) [Cu(L)Cl·OH2], (2) [Cu(L)O2NO], (3)
b
A value is presented in 10−4 cm−1
.
[Cu(L)OAc] and (4) [Cu(HL)O2SO2].

800
M.A. Diab et al. / Spectrochimica Acta Part A 77 (2010) 795–801
Table 5
Table 6
Bonding parameters and orbital reduction of complexes.
Electronic spectral data and ligand field parameters of the complexes.
2
Complexa
K|2|
K⊥2
K2
ˇ1
ˇ2
Complexa,b
Spectral bands
ꢅ2/ꢅ1
ꢃ1
ꢃ2
ꢃ3
(obs.) (cm-1
)
1
2
3
4
0.60
0.49
0.60
0.59
0.85
0.58
0.65
0.88
0.77
0.55
0.63
0.78
0.98
0.89
0.96
0.96
1.39
1.05
1.03
1.27
6
18,620
1.47
20,720
6680
6950
27,400, 30,675
34,250, 36,760
18,640
27,430, 30,700
34,260, 36,750
19,150
27,520, 30,700
34,260, 36,850
20,230
27,600, 30,700
34,260, 37,050
19,550
27,400, 29,120
34,360, 36,360
19,900
27,800, 30,700
34,800, 37,100
7
1.47
1.44
1.36
1.40
1.40
20,740
21,250
22,330
21,650
22,000
6690
6270
5270
5750
5800
6920
6855
6775
6975
6575
a
See footnote in Table 1.
8
␲-bonding, respectively and orbital reduction factor K2 (Table 5).
The value of ˛2 and ˇ2 was estimated from the following expres-
sion [39] where ˛2 = 1.0 indicates complete ionic character, where
˛2 = 0.5 denotes 100% covalent bonding, with the assumption of
negligibly small values of the overlap integral. The in-plane cova-
lency parameter ˛2(Cu) was calculated by following the relation:
9
10
11
ꢂ ꢃ
3
7
2
(Cu)
˛
= (A|| − 0.036) + (g|| − 2.0023) +
(g⊥ − 2.0023) + 0.04
(8)
a
See footnote in Table 1.
Diamagnetic.
b
The calculated value (Table 5) accounts for the fraction of the
unpaired electron density on copper(II) ion and hence the covalent
character of these polymer complexes. The in-plane and out-of-
plane ␲-bonding parameters ˇ1 and ˇ are obtained from the
expression [40]:
lower lying d-levels to the empty dx2−y2 orbital corresponding to
1A1g → A2g
,
1A1g → B1g and A1g → Eg d–d transitions [30] are
1
1
1
1
observed, respectively. Moreover in the polymer complexes, the
high intensity charge transfer absorption bands are also corre-
˛2ˇ12 = (g|| − 2.0023)ꢃ2/8ꢄo
˛2ˇ2 = (g⊥ − 2.0023)ꢃ1/2ꢄo.
(9)
1
1
1
1
sponding to A1g → A2u and A1g → Eu transitions, respectively.
The three orbital parameters ꢆ1, ꢆ2 and ꢆ3, were calculated using
a value of F2 = 10 and F4 = 600 cm−1 for a Slater Condon interelec-
tronic repulsion [30]. The ꢂ2/ꢂ1 were also calculated and are in
close agreement with data reported earlier for square planar com-
plexes.
(10)
The orbital reduction factors k and k , which are the measure
||
⊥
of the spin–orbit coupling constant (␭o = −823 cm−1) for free cop-
per(II) ion in these complexes are obtained by using the following
expression [13,41] and are shown in Table 5.
K|2| = (g|| − 2.0023)ꢃ2/8ꢄo
K⊥2 = (g⊥ − 2.0023)ꢃ1/2ꢄo
(11)
(12)
4. Concluding remarks
A series of Cu(II)/Pd(II)/Pt(II) polymer complexes with ligand
(HL) have been prepared and fully characterized. The charac-
teristics of the prepared polymer complexes are discussed. The
coordination behaviour of the anions is also discussed on the basis
of IR and molar conductance measurements. It was observed that
coordination of anions with metal was effected by number of coor-
dination sites, which was further confirmed by molar conductance.
The geometries of the polymer complexes are also effected by
number of coordination sites and ligand (HL) has two coordination
sites and formed different geometrical complexes with different
anions. Polymer complexes of ligand are compared and it observes
that these complexes are two coordinated in metal(II) anions com-
plexes. It proved direct effect of coordination sites on complexation
(Table 1).
ꢀ
ꢁ
1
3
K2
=
K|2| + K⊥2
(13)
The K and K parameters have been related by variously as
purely orbital coefficient and are related by K = ca. ˛, ˇ , and
||
⊥
||
1
K
⊥
= ca. ˛, ˇ, where ˛, ˇ , and ˇ are the coefficients of dx
→ dxy
−y
1
2
and dxz, dyz orbitals in MO’s to which they contribute; thus2˛ mea-
sure ␴-bonding, ˇ1 and ˇ are in-plane ␲-bonding and out-of-plane
␲-bonding coefficient, respectively. By assuming ˇ1 = 1 (since the
ligand has no lone pairs available on N atom for bonding with
(dxy). The values of ˛ and ˇ are calculated for copper(II) polymer
complexes and are reported in Tables 4 and 5. The estimated ˛-
coefficient for all complexes indicates fairly covalent ␴-bonding,
whereas ˇ coefficient suggests very little bonding of dxz, dyz with
orbital of axial anion in these polymer complexes. According to
Hathaway [36], K ≈ K⊥ ≈ 0.77 for pure in-plane ␴-bonding and
||
(1) The purpose for the synthesizing polymeric complexes was as
a model for the active site of the enjume and also a good model
for the physical properties of the protein active sites.
(2) It is also clear has a high affinity for chelation with metal ions
under study accordance to the increasing charge density of the
metal ion and hence to the increasing of their coordination
affinities.
K < K for in-plane ␲-bonding, while for out-of-plane ␲-bonding
||
⊥
K > K . In all the Cu(II) polymer complexes, it is observed that
||
||
⊥
⊥
K < K which is a good evidence for the assumed 2B1 ground state
for the polymer complexes and also, indicates the presence of sig-
nificant in-plane ␲-bonding. The values of bonding parameters ˛
and ˇ1 < 1.0 indicate significant in-plane ␴-bonding and in-plane
␲-bonding.
(3) The formulae [Cu(HL)O2SO2]n, [Cu(L)X]n (X = OAc, O2NO),
[M(L)Cl·OH2]n (M = Cu or Cd), [Pd(HL)X2], [Pd(HL)2](X2) (X = Cl
or Br), [Pt(HL)Cl2] and [Pd(L)2] has been proposed on the basis of
analytical and various physico-chemical data. The HL is bonded
3.5. Geometry of the Pd2+–Pt2+ polymer complexes
The magnetic moment studies that all the polymer complexes
of Pd(II)/Pt(II) are diamagnetic with spin-paired d8 system. The
electronic spectra of palladium(II) and platinum(II) polymer com-
plexes (Table 6) three spin-allowed d–d transition from three
to the metal ion in bidentate fashion through oxygen (of O
S O
group) and nitrogen atom [of imino nitrogen (NH/N) of the
guanidine group] as inferred from IR and 1H NMR spectra.

M.A. Diab et al. / Spectrochimica Acta Part A 77 (2010) 795–801
801
(4) These results also confirm the non-reactivity of the –CONH–
group in coordination (see Fig. 1).
(5) The calculations show that HL studied exist in a molecular form
with the intramolecular O–HN form.
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