Synthesis, structure and luminescence behaviour of bis(tridentate) Schiff base bridged dinuclear lead(II) pseudohalides

Article abstract of DOI:10.1016/j.molstruc.2009.12.015

Two pentacoordinated dinuclear lead(II) compounds [Pb₂(pbap)(N₃)₄] (1) and [Pb₂(pbap)(NCS)₄] (2) [pbap = N-((1-pyridin-2-yl)benzylidene)-N′-[2-(4-{2-[((1-pyridin-2-yl)benylidene)amino]ethyl}piperazin-1-yl)ethyl]amine] are prepared and characterized using microanalytical, spectroscopic, thermal and other physicochemical results. Single crystal X-ray diffraction measurements have been made to define the metal coordination spheres. Structural analyses reveal dinucleating bis(tridentate) behaviour of the hexadentate Schiff base (pbap) binding two metal ions. In the centrosymmetric dimers 1 and 2, each lead(II) center adopts a distorted square pyramidal geometry with PbN₅ chromophore ligated by each (N^p, Nⁱ, N^a) donor set of pbap and two N atoms of terminal pseudohalides. In DMF solutions at room temperature the complexes display high-energy intraligand ¹(π-π*) fluorescence.

Full text of DOI:10.1016/j.molstruc.2009.12.015

Journal of Molecular Structure 966 (2010) 102–106
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Synthesis, structure and luminescence behaviour of bis(tridentate) Schiff base
bridged dinuclear lead(II) pseudohalides
a
b
c
Soumi Chattopadhyay a, Kishalay Bhar a, , Sumitava Khan , Partha Mitra , Raymond J Butcher ,
*
Barindra K Ghosh a,
*
a Department of Chemistry, The University of Burdwan, Burdwan 713104, India
b Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata 700 032, India
c Department of Chemistry, Howard University, Washington, DC 20059, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Two pentacoordinated dinuclear lead(II) compounds [Pb2(pbap)(N3)4] (1) and [Pb2(pbap)(NCS)4] (2)
[pbap = N-((1-pyridin-2-yl)benzylidene)-N0-[2-(4-{2-[((1-pyridin-2-yl)benylidene)amino]ethyl}pipera-
zin-1-yl)ethyl]amine] are prepared and characterized using microanalytical, spectroscopic, thermal and
other physicochemical results. Single crystal X-ray diffraction measurements have been made to define
the metal coordination spheres. Structural analyses reveal dinucleating bis(tridentate) behaviour of the
hexadentate Schiff base (pbap) binding two metal ions. In the centrosymmetric dimers 1 and 2, each lea-
d(II) center adopts a distorted square pyramidal geometry with PbN5 chromophore ligated by each (Np,
Ni, Na) donor set of pbap and two N atoms of terminal pseudohalides. In DMF solutions at room temper-
Received 29 November 2009
Received in revised form 7 December 2009
Accepted 8 December 2009
Available online 16 December 2009
Keywords:
Dinuclear lead(II)
Pseudohalides
Bis(tridentate) Schiff base
X-ray structures
Luminescence
1
*
ature the complexes display high-energy intraligand
(
p
–
p
) fluorescence.
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
dene)-N0-[2-(4-{2-[((1-pyridin-2-yl)benzylidene)amino]ethyl}pip-
erazin-1-yl)ethyl]amine] (pbap) towards lead(II) in combination
with two pseudohalides viz. azide and thiocyanate, that remains
unexplored todate. Successfully, we have synthesized and X-ray
crystallographically characterized two dinuclear compounds,
[Pb2(pbap)(N3)4] (1) and [Pb2(pbap)(NCS)4] (2), where pbap shows
bis(tridentate) coordination motif assembling two lead(II) centers
and the pseudohalides remain as terminals. The details of synthe-
ses, structures, and thermal and luminescence behaviours of these
compounds are described here.
The study of mono-, di- and polynuclear complexes of lead(II) is
an important objective because of their interesting synthetic, struc-
tural, spectroscopic and optoelectronic features [1–4]. The essential
prerequisites for such research are the judicious choice [5] of organ-
ic spacers and inorganic/organic terminals/bridges that may lead to
directed properties. Recently, we are interested [6–8] in the con-
struction of different coordination molecules through variation of
ligand backbones and metal ion coordination environments; in this
regard, Schiff base spacers and pseudohalide terminals/bridges
have been used. Schiff bases [9] are recently focused by the coordi-
nation chemists as versatile organic ligands because of their pre-
parative accessibilities, structural varieties, varied denticities and
subtle steric and/or electronic control on their frameworks. Pseud-
ohalides like homoatomic azide and heteroatomic thiocyanate [10]
can bind metal ions with their different bonding modes [6–8,11–
14] affording a good number of mono-, di- and polymeric com-
pounds in concert with organic ligands of varied denticities. The
present work stems from our interest to examine the coordination
behaviour a hexadentate Schiff base, [N-((1-pyridin-2-yl)benzyli-
2. Experimental
2.1. General remarks and physical measurements
2.1.1. Materials
High purity 2-benzoylpyridine (Lancaster, UK), 2-[4-(2-amino-
ethyl)-piperazin-1-yl]ethylamine (Aldrich, USA), sodium azide (E.
Merck, India), ammonium thiocyanate (E. Merck, India) and lead(II)
acetate (E. Merck, India) were purchased from respective concerns
and used as received. All other chemicals and solvents were AR
grade and were used as received. The Schiff base (pbap) was pre-
pared following a reported method [15] described elsewhere. The
synthetic reactions and work-up were done in open air.
Caution! Azido compounds of metal ions are potentially explo-
sive [16] especially in the presence of organic ligands. Only a small
* Corresponding authors. Tel.: +91 342 2533913; fax: +91 342 2530452 (B. K.
Ghosh).
E-mail addresses: kishalaybhar@yahoo.com (K. Bhar), barin_1@yahoo.co.uk (B.K
Ghosh).
0022-2860/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2009.12.015

S. Chattopadhyay et al. / Journal of Molecular Structure 966 (2010) 102–106
103
Table 1
amount of these materials should be prepared and handled with
care.
Crystallographic data for 1 and 2.
Compounds
1
2
Formula
Weight
Crystal system
Space group
a/Å
C32H34N18Pb2
1086.21
Monoclinic
P21/c
16.1597(12)
8.0973(6)
15.3779(12)
90.00
110.982(2)
90.00
C36H34N10S4Pb2
1149.97
Monoclinic
C2/c
27.517(5)
10.674(2)
13.075(2)
90.00
100.837(3)
90.00
2.1.2. Physical measurements
Elemental analyses (carbon, hydrogen and nitrogen) were per-
formed on a Perkin–Elmer 2400 CHNS/O elemental analyzer. IR
spectra (KBr discs, 4000–300 cmꢀ1) were recorded using a Per-
kin–Elmer FTIR model RX1 spectrometer. Thermal behaviour was
investigated with a Perkin–Elmer Diamond TG/DT analyzer heated
from 30–750 °C under nitrogen. Molar conductances were mea-
sured using a Systronics conductivity meter where the cell con-
stant was calibrated with 0.01 M KCl solution and dry DMF was
used as solvent. Ground state absorption (in CH2Cl2, CH3OH and
DMF) and steady-state fluorescence measurements (in dry DMF)
were made with a Jasco model V-530 UV–vis spectrophotometer
and Hitachi model F-4500 spectrofluorimeter, respectively. Time-
resolved fluorescence measurements were carried out using a
time-correlated single photon counting (TCSPC) spectrometer
Edinburgh Instruments, model 199; a hydrogen filled coaxial flash
lamp with a pulse width of 1.2 ns at FWHM and a Philips XP-2020Q
photomultiplier tube were used as the excitation source and the
fluorescence detector.
b/Å
c/Å
a
°
b°
c
°
V/Å3
k/Å
1878.8(2)
0.71073
5.175
3771.8(12)
0.71073
2.024
q
calcd/g cmꢀ3
Z
2
4
T/K
293(2)
55.797
2400
1.35 to 21.30
ꢀ16, 16/ꢀ8, 8/ꢀ15,
15
12,029
2103
293(2)
9.180
2192
l
(mmꢀ1
)
F(000)
h ranges (°)
h/k/l
1.51 to 28.38
ꢀ34, 36/ꢀ14, 14/
ꢀ5,17
Reflections collected
13,907
4515
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
2103/0/235
0.779
4515/0/235
1.032
Final R indices [I > 2
r
(I)]
R = 0.0344,
wR = 0.0924
R = 0.0533,
wR = 0.1105
0.938 and ꢀ0.793
R = 0.0328,
wR = 0.0800
R = 0.0446,
wR = 0.0843
3.702 and ꢀ1.901
R indices (all data)
2.2. General synthesis of the complexes
Largest peak and hole
(eÅꢀ3
2.2.1. [Pb2(pbap)(N3)4] (1) and [Pb2(pbap)(NCS)4] (2)
)
A methanolic solution (5 mL) of pbap (0.503 g, 1 mmol) was
added dropwise to a solution of Pb(OAc)2.3H2O (0.758 g, 2 mmol)
in the same solvent (10 mL) followed by NaN3 (0.260 g, 4 mmol)
in MeOH (50 mL). The yellow solution was filtered and the super-
natant liquid was kept in air for slow evaporation. After a few days
single crystals of 1 that separated, were filtered, washed with tol-
uene and dried in vacuo over silica gel indicator. Yield: 0.815 g
(75%). 2 was prepared using a similar procedure and reaction stoi-
chiometry as described in 1 except that NH4SCN (0.304 g, 4 mmol)
instead of NaN3 was used. Yield: 0.804 g (70%). Anal. Calc. For
C32H34N18Pb2 (1): C, 35.38; H, 3.15; N, 23.31; Found: C, 35.29; H,
Weighting scheme: R =
R
jjFoj ꢀ jFcjj=
R
jFoj; wR ¼ ½
R
wðF2o ꢀ F2c Þ2=
R
wðF2o)2]1/2
.
Calc. w = 1/[r2 (Fo2) + (0.1000P)2 + 0.5611P] (1).
Calc. w = 1/[r2 (Fo2) + (0.0487P)2 + 1.8739P] (2); where P = (Fo2 þ 2F2c )/3.
3. Results and discussion
3.1. Synthesis and formulation
The pentacoordinated dinuclear compounds 1 and 2 initially
formed in methanolic solutions at room temperature containing
a 1:1:2 mixture of Pb(OAc)2ꢁ3H2O, pbap and NaN3 or NH4NCS as
is the case – a reactant ratio used to isolate octacoordinated mono-
nuclear lead(II) compounds of the composition [Pb(pbap)(X)2]
(X@N3ꢀ, NCSꢀ). However, microanalyses showed a 2:1:4 ratio of
metal, blocking ligand and pseudohalides. Reactant ratios corre-
sponding to the product stoichiometry afforded better yields of 1
and 2. The compounds were characterized using microanalyses
(C, H and N), solution electrical conductivity measurements, spec-
troscopic and thermal investigations. The microanalytical data are
in good agreement with the proposed formulas. The air-stable
complexes are soluble in a range of common organic solvents such
as methanol, ethanol, dichloromethane, acetonitrile, dimethyl-
formamide and dimethylsulphoxide, but are insoluble in water.
In DMF solutions, 1 and 2 behave as non-electrolytes as reflected
3.18; N, 23.39%. IR (KBr, cmꢀ1):
(C@N) + (C@C) 1618, 1592. KM (DMF, X
m
(N@N@N) 2019, 2000;
m
m
ꢀ1 cm2 molꢀ1): 5. UV–
vis (k, nm): 272. Anal. Calc. For C36H34N10S4Pb2 (2): C, 37.60; H,
2.98; N, 12.23; Found: C, 37.69; H, 2.93; N, 12.28%. IR (KBr,
cmꢀ1):
S) 768. KM (DMF,
m
(N@C@S) 2036, 2020;
m(C@N) + m(C@C) 1626, 1592; m(C–
X
ꢀ1 cm2 molꢀ1): 4. UV–vis (k, nm): 273.
2.3. X-ray crystallographic study
Single crystals of 1 and 2 suitable for X-ray analyses were se-
lected from those obtained by slow evaporation of methanolic
solutions of the reaction mixtures at 298 K. Diffraction data were
collected at 293(2) K on a Bruker SMART APEX-II CCD area-detector
diffractometer using graphite monochromated Mo-K
a radiation
in their low conductivity values (ꢂ5
X
ꢀ1 cm2 molꢀ1) [21]. In IR,
(k = 0.71073 Å). The unit cell parameters were obtained from
SAINT; absorption corrections were performed with SADABS [17].
A summary of the crystallographic data and structure determinant
parameters is given in Table 1. Of 12,029 (1) and 13,907 (2) col-
lected reflections, 2103 (1) and 4515 (2) unique reflections were
m
as(X) stretches appear as strong bands at 2019 and 2000 cmꢀ1 in
1 and at 2036 and 2020 cmꢀ1 in 2 indicating the existence of differ-
ent force constants of the pseudohalides in each compound. The
positions of bands are in line with terminal nature of the pseud-
ohalides in 1 and 2 and N-coordination of the thiocyanates [11]
recorded using the
x scan technique. The structures were solved
in 2. A band corresponding to the
m(C–S) stretching frequency ap-
by direct methods using SHELXS-97 [18]. All hydrogen atoms were
fixed geometrically and refined using a riding model. In the final
difference Fourier maps, the residual maximum and minimum
were 0.938 and ꢀ0.793 eÅꢀ3 (for 1) and 3.702 and ꢀ1.901 eÅꢀ3
(for 2). All calculations were carried out using PLATON [19] and
ORTEP-32 [20].
pears at 768 cmꢀ1 in 2. The Schiff base, pbap, in the metal bound
states exhibit mas(C@N) plus mas(C@C) stretching vibrations [22] at
ꢂ1620 and ꢂ1590 cmꢀ1. All other characteristic organic ligand
vibrations are seen in the range 1600–600 cmꢀ1. Light yellow solu-
tions of 1 and 2 in CH2Cl2/MeOH/DMF exhibit strong absorptions at

104
S. Chattopadhyay et al. / Journal of Molecular Structure 966 (2010) 102–106
Fig. 1. ORTEP representation of [Pb2(pbap)(N3)4] (1) with atom numbering scheme and 20% probability ellipsoids for all non-hydrogen atoms.
272 and 273 nm, respectively due to ligand based transition [23].
1 and 2. The coordination polyhedron around each pentacoordinat-
The solvent-independent spectral behaviour is presumably due to
ed lead(II) center is best described as a distorted square pyramid as
exemplified by its tau parameter (s = 0.362 in 1 and s = 0.290 in 2)
*
p–p
transition.
[24] with PbN5 chromophore. The distortion from ideal square
pyramidal geometry is due to asymmetric nature of the Schiff base
and deviations of the refine angles (90°/180°) formed at the metal
center. In the centrosymmetric dimers, two lead(II) centers (Pb1/
Pb1a in 1 and Pb/Pba in 2) are bound by bis(tridentate) behaviour
of pbap through donation of one Np (N4/N4a in 1 and N1/N1a in 2),
one Ni (N5/N5a in 1 and N2/N2a in 2) and one Na (N16/N16a in 1
and N3/N3a in 2) atoms to each metal; fourth and fifth coordina-
tion sites are occupied with two terminal N atoms (N6/N6a and
N7/N7a in 1 and N1A/N1Aa and N1B/N1Bb in 2) of the pseudoha-
lides. The intramolecular Pb. . .Pb distances are 6.8125(7) Å in 1
and 6.8659(11) Å in 2. The basal dimeric plane consists of four N
(Np, Na) atoms of pbap along with four terminal azide N atoms in
1 and four terminal thiocyanate N atoms in 2, while the apical po-
sition of each lead(II) center is occupied by Ni atoms of pbap. Each
lead(II) center deviates (0.764 Å in 1 and 0.830 Å in 2) opposite to
the apical pseudohalide from the mean basal plane. Pb–N(basal)
3.2. Description of the crystal structures of [Pb2(pbap)(N3)4] (1) and
[Pb2(pbap)(NCS)4] (2)
Structural analyses reveal that crystal lattices of 1 and 2 consist
of dinuclear neutral [Pb2(pbap)(N3)4] and [Pb2(pbap)(NCS)4] units.
ORTEP diagrams with atom numbering schemes of 1 and 2 are
shown in Figs. 1 and 2, respectively. Selected bond distances and
bond angles relevant to the metal coordination spheres are set in
Tables 2 and 3.
The tailored hexadentate Schiff base (pbap) belongs to a sym-
metrical Np, Ni, Na, Na, Ni, Np type, where Np, Ni and Na are N(pyr-
idine), N(imine) and N(amine) donor centers, respectively. The
dinucleating bis(tridentate) view of pbap and two pairs of donor
(Np, Ni, Na) set arrangements through incorporation of the ring
within the bridge in 1 and 2 is evident in Figs. 1 and 2. The Schiff
base (pbap) is placed in a crystallographic inversion center in both
Fig. 2. Molecular structure of [Pb2(pbap)(NCS)4] (2); (ORTEP, 20% ellipsoids).

S. Chattopadhyay et al. / Journal of Molecular Structure 966 (2010) 102–106
105
Table 2
Selected bond distances (Å) and bond angles (°) for 1.
Bond distances
Pb(1)–N(4
Pb(1)–N(5)
Pb(1)–N(6)
Pb(1)–N(7)
Pb(1)–N(16)
2.501(9)
N(6)–N(8)
N(8)–N(9)
N(7)–N(11)
N(11)–N(10)
1.18(2)
1.17(2)
1.199(16)
1.165(17)
2.435(10)
2.619(12)
2.475(11)
2.682(11)
Bond angles
N(6)–Pb(1)–N(4)
N(6)–Pb(1)–N(5)
N(6)–Pb(1)–N(7)
N(6)–Pb(1)–N(16)
N(4)–Pb(1)–N(5)
N(8)–N(6)–Pb(1)
N(7)–N(11)–N(10)
81.3(4)
77.8(4)
155.4(4)
82.2(4)
64.6(3)
115.1(10)
177.2(14)
N(4)–Pb(1)–N(7)
N(4)–Pb(1)–N(16)
N(5)–Pb(1)–N(7)
N(5)–Pb(1)–N(16)
N(7)–Pb(1)–N(16)
N(11)–N(7)–Pb(1)
N(6)–N(8)–N(9)
83.6(3)
133.7(3)
78.2(3)
69.7(3)
94.5(4)
115.5(8)
179.2(18)
Table 3
Fig. 3. Emission spectra of: pbap, 1 and 2 (fluorescence in DMF solutions at 298 K).
Selected bond distances (Å) and bond angles (°) for 2.
Bond distances
Pb–N(1)
Pb–N(2)
Pb–N(3)
Pb–N1A
Pb–N1B
2.488(4)
2.460(4)
2.580(3)
2.537(5)
2.627(5)
N1A–C1A
N1B–C1B
S1A–C1A
S1B–C1B
1.168(7)
1.170(7)
1.623(6)
1.634(6)
at 426 and 418 nm upon excitation at the corresponding absorp-
tion bands (272 nm in 1 and 273 nm in 2) of the compounds. The
lifetimes are 2.56 (1) and 2.52 ns (2). The red shift (48 nm in 1
and 40 nm in 2) as well as greater intensity of luminescence behav-
iour may be attributed [25] to the metal-perturbed intraligand
Bond angles
1
*
(p–p
) transition becoming more permissible upon coordination
N(2)–Pb–N(1)
N(1)–Pb–N(3)
N(2)–Pb–N(3)
N(2)–Pb–N(1B)
N(1)–Pb–N(1B)
N(1A)–Pb–N(3)
N(2)–Pb–N(1A)
65.67(13)
133.24(12)
68.61(12)
76.31(13)
79.33(14)
83.93(14)
74.57(13)
N(1B)–Pb–N(3)
N(1)–Pb–N(1A)
81.02(14)
93.04(14)
150.46(14)
178.9(5)
179.2(5)
124.0(4)
137.1(4)
of the Schiff base.
N(1A)–Pb–N(1B)
N(1A)–C(1A)–S(1A)
N(1B)–C(1B)–S(1B)
C(1B)–N(1B)–Pb
C(1A)–N(1A)–Pb
4. Conclusions
We are able to prepare and X-ray crystallographically charac-
terize two new luminous pentacoordinated neutral dinuclear com-
pounds of lead(II) in concert with a Schiff base and pseudohalides
through single-pot reactions of the molecular building units in pre-
assigned ratios. The interesting feature is the bis(tridentate) coor-
dination behaviour of the Schiff base bridging two metal ions.
New variety of dinuclear compounds containing terminal pseud-
ohalides is the result from such study.
bond lengths are larger than Pb–N(apical) distances (Tables 2 and
3). The quasi-linear pseudohalides are coordinated to lead(II) cen-
ter in a bending fashion. In 1, N(6)–N(8) and N(7)–N(11) bond
lengths [1.18(2) and 1.199(16) Å] are larger than that [1.17(2)
and 1.165(17) Å] in N(8)–N(9) and N(11)–N(10) confirming coordi-
nation of N(6) and N(7) to the lead(II) center. In 2, N (N1A, N1B)
atoms of the terminal thiocyanates are bound to the metal centers
rather than S (S1A and S1B) atoms.
Acknowledgements
Financial support from the DST, CSIR and UGC, New Delhi, India
is gratefully acknowledged. S.C. is grateful to the UGC and K.B. and
S.K., to the CSIR, New Delhi, India for fellowships. The authors also
acknowledge the use of DST-funded National Single Crystal X-ray
Diffraction Facility at the Department of Inorganic Chemistry, IACS,
Kolkata, India for crystallographic study.
3.3. Thermal studies
To examine thermal stabilities of the compounds 1 and 2, ther-
mogravimetric (TG) and differential thermal analyses (DTA) were
made between 30 and 750 °C in a static atmosphere of N2. The
thermal decomposition behaviours of both 1 and 2 are similar. 1
is stable up to 208 °C, whereas 2 shows thermal stability up to
240 °C. TG-DTA curve indicates gradual decomposition of the li-
gands in the 208–730 °C temperature range with an endothermic
effect at 219 °C in 1 and in the 240–730 °C temperature range with
an exothermic effect at 252 °C in 2. In summary, the analyses show
greater thermal stability of 2 over 1.
Appendix A. Supplementary data
Crystallographic data for the structural analyses (excluding
structure factors) have been deposited with the Cambridge Crystal-
lographic Data Center (CCDC Nos. 753619 for 1 and 753620 for 2).
Copies of this information can be had free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44
1223 336033; e-mail: deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk). Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.molstruc.2009.12.015.
3.4. Luminescence properties
The photoluminescence behaviours of the free Schiff base ligand
(pbap) and its corresponding lead(II) pseudohalide compounds (1
and 2) were studied in DMF solutions at room temperature. The
spectral patterns are depicted in Fig. 3. Upon photoexcitation at
the corresponding absorption band (270 nm) in DMF solution, free
ligand exhibits a broad fluorescent emission centered at 378 nm.
However, 1 and 2 show a large red-shifted but more intense pho-
toluminescence characteristics with main emissions respectively
References
[1] (a) R.L. Davidovich, V. Stavila, D.V. Marinin, E.I. Voit, K.H. Whitmire, Coord.
Chem. Rev. 253 (2009) 1316;
(b) D.-Q. Li, X. Liu, J. Zhou, Inorg. Chem. Commun. 11 (2008) 367;
(c) S. Hazra, S. Majumder, M. Fleck, R. Koner, S. Mohanta, Polyhedron 28 (2009)

106
S. Chattopadhyay et al. / Journal of Molecular Structure 966 (2010) 102–106
(c) F.A. Mautner, F.R. Louka, T. LeGuet, S.S. Massoud, J. Mol. Struct. 919 (2009)
2871;
(d) J. Yang, J.-F. Ma, Y.-Y. Liu, J.-C. Ma, S.R. Batten, Cryst. Growth Des. 9 (2009)
1894.
[2] (a) F. Marandi, B. Mirtamizdoust, A.A. Soudi, H.-K. Fun, Inorg. Chem. Commun.
10 (2007) 174;
(b) C. Kazak, M.B. Arslan, S. Karabulut, A.D. Azaz, H. Namli, R. Kurtaran, J. Coord.
Chem. 62 (2009) 2966.
[3] (a) C. Platas-Iglesias, D. Esteban-Gomez, T. Enriquez-Perez, F. Avecilla, A.D.
Blas, T. Rodriguez-Blas, Inorg. Chem. 44 (2005) 2224;
(b) G.H. Shahverdizadeh, A.A. Soudi, A. Morsali, P. Retaillean, Inorg. Chim. Acta
361 (2008) 1875;
(c) B. Ding, Y.Y. Liu, X.-J. Zhao, E.-C. Yang, X.G. Wang, J. Mol. Struct. 920 (2009)
248.
[4] (a) Special issue on Molecular materials in electronic and optoelectronic
devices, Acc. Chem. Res. 32 (1999) 3;
(b) M. Petty, Molecular Electronics: From Principles to Practice, Wiley,
Chichester, 2008.
[5] J.J. Perry, J.A. Perman, M.J. Zaworotko, Chem. Soc. Rev. 38 (2009) 1400.
[6] (a) T.K. Karmakar, S.K. Chandra, J. Ribas, G. Mostafa, T.-H. Lu, B.K. Ghosh, Chem.
Commun. (2002) 2364;
196.
[12] (a) U. Mukhopadhyay, I. Bernal, S.S. Massoud, F.A. Mautner, Inorg. Chim. Acta
357 (2004) 3673;
(b) F.A. Mautner, C.N. Landry, A.A. Gallo, S.S. Massoud, J. Mol. Struct. 837
(2007) 72;
(c) B. Samanta, J. Chakraborty, C.R. Choudhury, S.K. Dey, D.K. Dey, S.R. Batten, P.
Jensen, G.P.A. Yap, S. Mitra, Struct. Chem. 18 (2007) 33;
(d) S.S. Massoud, K.T. Broussard, F.A. Mautner, R. Vecente, M.K. Saha, I. Bernal,
Inorg. Chim. Acta 361 (2008) 123.
[13] (a) S.S. Massoud, F.A. Mautner, R. Vicente, A.A. Gallo, E. Ducasse, Eur. J. Inorg.
Chem. (2007) 1091;
(b) M.-L. Bonnet, C. Aronica, G. Chastanet, G. Pilet, D. Luneau, C. Mathoniere, R.
Clerse, V. Robert, Inorg. Chem. 47 (2008) 1127;
(c) Z.-L. Chen, C.-F. Jiang, W.-H. Yan, F.-P. Liang, S.R. Batten, Inorg. Chem. 48
(2009) 4674.
[14] (a) Y.-Q. Sun, D.-Z. Gao, W. Dong, D.-Z. Liao, C.-X. Zhang, Eur. J. Inorg. Chem.
(2009) 2825;
(b) A.D. Khalaji, M. Weil, H. Hadadzadeh, M. Daryanavard, Inorg. Chim. Acta
362 (2009) 4837;
(b) T.K. Karmakar, B.K. Ghosh, A. Usman, H.-K. Fun, E. Riviere, T. Mallah, G.
Aromi, S.K. Chandra, Inorg. Chem. 44 (2005) 2391.
(c) M. Sarkar, R. Clerac, C. Mathoniere, N.G.R. Hearns, V. Bertolasi, D. Ray, Eur. J.
Inorg. Chem. (2009) 4675.
[7] (a) S.H. Rahaman, R. Ghosh, T.-H. Lu, B.K. Ghosh, Polyhedron 24 (2005) 1525;
(b) S.H. Rahaman, H.-K. Fun, B.K. Ghosh, Polyhedron 24 (2005) 3091;
(c) S.H. Rahaman, H. Chowdhury, H.L. Milton, A.M.Z. Slawin, J.D. Woollins, B.K.
Ghosh, Inorg. Chem. Commun. 8 (2005) 1031.
[15] H. Chowdhury, R. Ghosh, S.H. Rahaman, B.K. Ghosh, Polyhedron 26 (2007)
5023.
[16] A. Mohamadou, G.A. van Albada, I. Mutikainen, U. Turpeinen, J. Marrot, J.
Reedijk, Polyhedron 28 (2009) 2813.
[8] (a) T.K. Karmakar, G. Aromi, B.K. Ghosh, A. Usman, H.-K. Fun, T. Mallah, U.
Behrens, X. Solans, S.K. Chandra, J. Mater. Chem. 16 (2006) 278;
(b) S.H. Rahaman, D. Bose, R. Ghosh, G. Mostafa, H.-K. Fun, B.K. Ghosh, Struct.
Chem. 18 (2007) 237;
[17] G.M. Sheldrick, SADABS. Program for Empirical Absorption Correction of Area
Detector Data, University of Göttingen, Germany, 1996.
[18] G.M. Sheldrick, Acta Cryst. A64 (2008) 112.
[19] A.L. Spek, Acta Cryst. D 65 (2009) 148.
(c) B.N. Sarkar, K. Bhar, S. Kundu, H.-K. Fun, B.K. Ghosh, J. Mol. Struct. 936
(2009) 104.
[20] L.J. Farrugia, J. Appl Crystallogr. 30 (1997) 565.
[21] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81.
[9] (a) A.D. Garnovskii, A.L. Nivorozhkin, V.I. Minkin, Coord. Chem. Rev. 126 (1993)
1;
[22] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination
Compounds, Part B, fifth ed., John Wiley & Sons, New York, 1997.
[23] (a) A.B.P. Lever, Inorganic Electronic Spectroscopy, second ed., Elsevier, New
York, 1984;
(b) J. Garcia Sole, L.E. Bausa, D. Jaque, An Introduction to the Optical
Spectroscopy of Inorganic Solids, John Wiley & Sons, New York, 2005.
[24] A.W. Addision, T.N. Rao, J. Reedijk, J.V. Rijn, G.C. Verschoor, J. Chem. Soc. Dalton
Trans. (1984) 1349.
[25] (a) B. Dutta, P. Bag, U. Florke, K. Nag, Inorg. Chem. 44 (2005) 147;
(b) S. Banthia, A. Samanta, J. Phys. Chem. B 110 (2006) 6437;
(c) H.A. Habib, A. Hoffmann, H.A. Hoppe, G. Stelnfeld, C. Janiak, Inorg. Chem. 48
(2009) 2166.
(b) V. Alexander, Chem. Rev. 95 (1995) 273;
(c) P.A. Vigato, S. Tamburini, L. Bertolo, Coord. Chem. Rev. 251 (2007) 1311.
[10] (a) A.M. Golub, H. Kohler, V.V. Skopenko (Eds.), Chemistry of Pseudohalides,
Elsevier, Amsterdam, 1986;
(b) D.A. Buckingham, Coord. Chem. Rev. 135–136 (1994) 587;
(c) J. Ribas, A. Escuer, M. Monfort, R. Vicente, R. Cortes, L. Lezana, T. Rojo, Coord.
Chem. Rev. 193–195 (1999) 1027.
[11] (a) S.S. Massoud, F.A. Mautner, M. Abu-Youssef, N.M. Shuaib, Polyhedron 18
(1999) 2287;
(b) S.S. Massoud, F.A. Mautner, Inorg. Chim. Acta 358 (2005) 3334;