Synthesis, crystal structure, and properties of the enantiotopic complex constructed from chiral ligand H2bpb, [Co (H2bpb) 2 (NCS)2 (CH3OH)2] (H 2,bpb = 1, 2-Bis (3-pyridylcarboxamide)benzene)

Article abstract of DOI:10.1080/15533170802265699

A six-coordinating cobalt(II) complex, [Co(H2bpb)2(NCS)2 (CH3OH)2], where H2bpb is 1, 2-bis(3-pyridylcarboxamide) benzene, was prepared and characterized by IR spectrum and thermal analysis, and its crystal structure was determined X-ray analysis. It crystallizes in the triclinic system with space group P-1 with = 8.7005(9) , b = 9.6114(10) , c = 13.767(2) , = 101.393(2), = 93.185(2), = 114.5180(10), V = 1014.5(2) , Z = 1. Fluorescent and thermal properties of the complex were also investigated.

Full text of DOI:10.1080/15533170802265699

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 38:539–544, 2008
Copyright © Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533170802265699
Synthesis, Crystal Structure, and Properties of the
Enantiotopic Complex Constructed from Chiral Ligand
H2bpb, [Co (H2bpb)2 (NCS)2 (CH3OH)2] (H2bpb = 1, 2-Bis
(3-Pyridylcarboxamide)Benzene)
Ping Zhang, Ben-Lai Wu, Yun-Yin Niu, Hong-Yun Zhang, Cao-Yuan Niu,
and Hong-Wei Hou
Department of Chemistry, Zhengzhou University, Zhengzhou, P. R. China
structural chemistry and the kinetics of reactions.[9] Cobalt
A six-coordinating cobalt(II) complex, [Co(H2bpb)2(NCS)2
(CH3OH)2], where H2bpb is 1, 2-bis(3-pyridylcarboxamide) ben-
zene, was prepared and characterized by IR spectrum and thermal
analysis, and its crystal structure was determined X-ray analysis.
It crystallizes in the triclinic system with space group P-1 with a =
complexes are useful in highly selective catalytic oxidation
reactions using molecular oxygen, as models for oxygenases,
peroxydases, or mono- and dioxygenases , for example,
catalyzing the oxidation of phenols, alcohols, flavonoides, ni-
troalkanes, hydrazines, or olefins. While extended coordination
networks derived from pyridylamide ligands have been reported
with the metal centers Ag(I), Au(I), Pd(II), and Pt(II),[10−12]
compounds similar to Co(II) have not been studied extensively.
In the present communication, we have reported the synthesis
of the complex [Co (H2bpb)2(NCS)2(CH3OH)2] (H2bpb = 1,
2-bis(3-pyridylcarboxamide)benzene) and turned our attention
to characterization of the complex.
˚
˚
˚
8.7005(9) A, b = 9.6114(10) A, c = 13.767(2) A, α = 101.393(2), β =
˚
93.185(2), γ = 114.5180(10), V = 1014.5(2) A, Z = 1. Fluorescent
and thermal properties of the complex were also investigated.
Keywords cobalt(II) complex, crystal structure, fluorescent, thermal
analysis
INTRODUCTION
The syntheses of ligands based on 1,2-disubstituted ben-
zene have attracted a great deal of attention, with a broad array
of both acyclic and macrocyclic ligands reported.[1] In partic-
ular,diamides incorporating a CO NH benzene NH CO
core based on 1,2-benzenediamine have been examined, with in-
terest in these compounds extending to potential applications as
diverse as asymmetric catalysis,[2] molecular receptors,[3] den-
drite synthesis,[4] and platinum(II) complexes with antitumor
properties.[5] The carboxamide [ C(O)NH ] group, which is
the primary structure of proteins, is all over in the nature and an
important ligand construction unit for coordination chemists.[6]
In the control of molecular architectures pyridine carboxamide
ligands are used extensively.[7]
EXPERIMENTAL
Materials and Methods
Nicotinic acid was analytical pure grade from Alfa Aesar,
phthalamine and other reagents were also analytical pure grade
and purchased from TianJin Reagent Factory, used without fur-
ther purification. The 1, 2-bis(3-pyridylcarboxamide)benzene
(H2bpb) was synthesized following a procedure reported
previously[13] with a yield of 70%. Thionyl chloride and pyridine
were redistilled. Melting points were taken on an XT-5 micro-
scope melting point apparatus. IR spectra were recorded on a
Nicolet IR-470 spectrometer from KBr pellets in range 4000–
400 cm−1. Crystallographic data were measured on a Bruker
APEX-II area-detector diffractometer with Mo-Ka radiation (λ
Coordination compounds containing the thiocyanate ligand
are usually reported.[8] Thiocyanate plays a diverse role in the
˚
= 0.71073 A). Thermal analysis curve was scanned in the range
of 35–800◦C with argon atmosphere on STA 409 PC thermal an-
alyzer. The fluorescence spectra were recorded in the solid state
at room temperature on HITRCHI F-4500 Fluorophotometer.
Received 12 August 2008; accepted 29 January 2008.
We gratefully acknowledge financial support from the National
Natural Science Foundation of China (20671083) and the Science and
Technology Foundation of Henan Province (0524270061).
Address correspondence to Hong-Yun Zhang, Department of
Chemistry, Zhengshou University, Zhengzhou 450052, P. R. China.
E-mail: wzhy917@zzu.edu.cn
Synthesis of the Complex [Co(H2bpb)2(NCS)2(CH3OH)2]
At room temperature, a clear DMF solution (5 mL) of H2bpb
(63.7 mg, 0.2 mmol) was slowly added to a methanol solution
(10 mL) of CoSO4 (56.2 mg, 0.2 mmol), then 5 mL solution
539

540
P. ZHANG ET AL.
TABLE 1
TABLE 2
◦
˚
Crystallographic data and structure refinement for complex
Selected bond distances (A) and angles ( ) for cobalt(α)
complex
Structural parameter
Co(1)-N(5)
Co(1)-N(5)#1
Co(1)-O(3)
Co(1)-O(3)#1
Co(1)-N(1)
Co(1)-N(1)#1
2.0814(16)
2.0814(16)
2.1011(14)
2.1011(14)
2.1855(14)
2.1855(14)
Empirical formula
M
C40 H36 Co N10 O6 S2
875.84
Crystal group
Space group
Triclinic
P-1
˚
a/A
8.7005(9)
9.6114(10)
13.767(2)
101.393(2)
93.185(2)
114.5180(10)
1014.5(2)
1.434
˚
b/A
N(5)-Co(1)-N(5)#1
N(5)-Co(1)-O(3)
N(5)#1-Co(1)-O(3)
N(5)-Co(1)-O(3)#1
N(5)#1-Co(1)-O(3)#1
O(3)-Co(1)-O(3)#1
N(5)-Co(1)-N(1)
N(5)#1-Co(1)-N(1)
O(3)-Co(1)-N(1)
O(3)#1-Co(1)-N(1)
N(5)-Co(1)-N(1)#1
N(5)#1-Co(1)-N(1)#1
O(3)-Co(1)-N(1)#1
O(3)#1-Co(1)-N(1)#1
N(1)-Co(1)-N(1)#1
180.0
˚
c/A
88.50(7)
91.50(7)
91.50(7)
88.50(7)
179.999(1)
90.16(6)
89.84(6)
89.73(6)
90.27(6)
89.84(6)
90.16(6)
90.27(6)
89.73(6)
180.0
α/◦
β/◦
γ /◦
3
˚
V /A
Dc/g.cm−3
Z
1
µ/mm−1
0.586
Crystal size/mm3
Reflns collected/Unique
R1, ωR2[I>2σ(I)]
0.34 × 0.24 × 0.23
7811/3769
0.0298a; 0.0802b
aR1 = ꢀ||Fo| − |Fc||/ꢀ|Fo|.
bωR2 = [ꢀ(||Fo| − |Fc||)2/ꢀω|Fo| ]1/2
.
2
Symmetry transformations used to generate equivalent atoms: #1
−x + 2, −y + 1, −z + 1.
of potassium thiocyanate (19.4 mg, 0.2 mmol) in methanol was
added to the above mixture with continuous stirring for 30 min
and filtered. The filtrate was allowed undisturbed evaporation
at ambient temperature, and pink block crystals suitable for X-
ray single crystal diffraction analysis were collected by being
filtered and washed with methanol and acetone for one week.
Yield: 40%. IR (KBr, υ cm−1): 3319 m, 3271 m, 2052 s, 1657
s, 1598 s, 1533 s, 1317 s, 1199 m, 1028 m, 918 m, 771 m, 702
m.
The characteristic absorption bands at 1665, 1529, and 1283
cm−1 for H bpb are due to amide [mainly ν (C O)], amide II
ꢀ
2
[mainly ν (C N)], and amide III [mainly δ(N H)] vibrations,
respectively.
The complex has characteristic IR bands at 1657, 1533, and
1316 cm .
−1 [16] The amide [mainly ν (C O)] did not disappear
ꢀ
and trivially shift to 1657 cm−1, which suggests that in the
complex H2bpb still is in keto-form and the non-coordination
of this fragment. Comparing the corresponding bands of the
complex with the free ligand, the obvious changes are found in
X-Ray Structure Determination
Crystallographic data for the title compound were collected at
291(2) K on a Bruker APEX-II area-detector diffractometer with
˚
amide and III vibrations. The amide I band shifts to a lower
ꢀ
Mo-Ka radiation (λ = 0.71073 A). Absorption corrections were
frequency and the amide III band shifts to a higher frequency.
These facts may be explained by inter- and/or intramolecular
hydrogen bonding and C O group and N H group did not
applied by using SADABS. The structure was solved with direct
methods and refined with full-matrix least-squares techniques
on F2 using the SHELXTL program package.[14] All of the
non-hydrogen atoms were refined anisotropically. The hydro-
gen atoms were assigned with common isotropic displacement
factors and included in the final refinement by using geometri-
cal restraints. Crystal data are summarized in detail in Table 1.
Selected bond lengths and angles are shown in Table 2.
TABLE 3
Hydrogen bonds for L (A and )
◦
˚
D-H . . .A
d(D-H) d(H. . .A)
d(D. . .A)
<(DHA)
N(2)-H(2N). . .O(2)#2 0.86
N(3)-H(3N). . .O(1)#3 0.86
O(3)-H(3E). . .N(4)#4 0.79(3) 1.99(3)
2.07
2.13
2.8979(18)
2.8789(19)
2.762(2)
161.7
144.9
170(3)
RESULTS AND DISCUSSION
IR Spectra
Symmetry transformations used to generate equivalent atoms: #1 −x
+ 2, −y + 1, −z + 1, #2 −x + 1, −y + 1, −z, #3 −x + 1, −y, −z, #4
x + 1, y, z.
In IR spectrum of the free ligand H2bpb, a band of medium in-
tensity, shows at 3282 cm−1 and is recognized as the ν (NH).[15]

COBALT(II) COMPLEXES
541
FIG. 1. Structure of [Co(H2bpb)2(NCS)2(CH3OH)2] with the atom labeling scheme (30% probability ellipsoids). Hydrogen atoms have been omitted for clarity.
FIG. 2. Two chiral conformations of H2bpb (hydrogen atoms have been omitted for clarity).
FIG. 3. One-dimensional ordering and of hydrogen-bond system [Co (H2bpb)2(NCS)2(CH3OH)2].

542
P. ZHANG ET AL.
Described Crystal Structure of the Complex
The crystal structure of the complex, [Co (H2bpb)2(NCS)2
(CH3OH)2], is shown in Figure 1 and selected bond dis-
tances and angles are listed in Table 2. The cobalt ion sits
on a crystallographically imposed center. Two H2bpb lig-
ands as monodentate occupy two equatorial positions in trans
through one pyridine nitrogen coordinating to Co (II) respec-
tively. There are two thiocyanates on the position of equato-
rial plane through nitrogen atom also coordinating to Co(II) in
trans respectively. Axial positions are occupied by two oxy-
gen atoms of two methanol molecules. Thus, the cobalt ion
has an octahedral geometry, comprising CoN4O2 architectural
coordination environment. The ligand bite angles of N1(py)-
CoII-O3(methanol) are 89.73(6)◦ and 90.27(6)◦, respectively;
those of N5(thiocyanate)-CoII-O3(methanol) are 88.50(7)◦ and
91.50(7)◦, respectively; those of N1(py)-CoII-N5 (thiocyanate)
are 90.16(6)◦ and 89.84(6)◦, respectively (Table 2). The bond
angles around Co(α) are fairly close to 90◦, indicating a slight
distortion of the octahedral coordination sphere. Mean value
FIG. 4. Structure of the dimeric unit of [Co (H2bpb)2 (NCS)2 (CH3OH)2]
with the atom labeling scheme (parts of hydrogen atoms have been omitted for
clarity).
˚
(2.1855(14) A) of Co-N (py) lengths is appreciably longer than
[16]
˚
literature mean value (2.117(3) A).
In this conformation,
plane I [C(7), C(8), C(9), C(10), C(11), and C(12)] makes di-
hedral angles 91.8◦and 145.1◦ with plane II [N(1), C(1), C(2),
C(3), C(4), and C(5)] and plane III [N(4), C(14), C(15), C(16),
C(17), and C(18)], respectively. Plane II makes a dihedral angle
take part in coordination with metal. The IR spectrum of the
complex exhibits additional strong absorption bands at 2052
cm−1, which should be ascribed to the occurrence of the SCN
group.
FIG. 5. The stereo drawings of the crystal packing of the complex viewed along b axis.

COBALT(II) COMPLEXES
543
FIG. 6. TG/DSC curves for complex [Co (H2bpb)2(NCS)2(CH3OH)2]. The
curves were obtained in dynamic nitrogen atmosphere (approximately 50.0 mL
FIG. 7. The fluorescence excitation spectra of ligand and the complex in solid
state.
min−1) and heating rate of 10◦C min−1
.
molecules of coordinated methanol of the complex. After loss of
coordinated methanol, the TGA curve shows that the complex
is stable up to 272◦C. The intermediate [Co (H2bpb)2 (NCS)2]
is not thermally stable, because a new endothermic decompo-
sition starts at 272◦C. The degradation of the ligand H2bpb is
a complicated process and takes place in the temperature range
272–800◦C. The thermal decomposition process of the H2bpb is
not easy to understand because of unclear decomposition steps.
The mass loss observed between 270 and 351◦C with a DSC
peak at 272◦C ꢁm = 55.14%. At higher temperatures (351–
800◦C, a gradual mass loss totals 12.48%, corresponding to
the elimination of two molecule of SCN (calculated value =
13.25%). The total experimental mass loss value is 75.04% and
the final residue at 800◦C may be the buildup of carbon and
inorganic compound CoO.
62.0◦ with the plane III (as in Figure 1). These dihedral angles
reveal that all three aromatic rings are not coplanar to each other
in crystal structural unit.
Due to stereo-isomer influencing, the ligand H2bpb, which
coordinates cobalt(II) in trans form through one pyridine ni-
trogen atom, exists in the chiral conformations A or B in
solid state the complex, as shown in Figure 2. It is seen from
Figure 1 that two H2bpb and two thiocyanates coordi-
nate to Co(II) in trans form, respectively, to form the
complex having reverse center of symmetry and reverse
plane of symmetry. So the chiral ligand H2bpb coor-
dinates to Co(II) to form a mononucleated enantiotopic
complex.
The pyridine nitrogens N(3) and methanol hydroxyls form
strong intermolecular hydrogen bonds (O(3)-H(3E)· · ·N(4) =
˚
2.762(2) A). The molecules of the complex are linked to-
Photoluminescent Properties
gether through solvent-mediated hydrogen bonding of the kind
. . .
The fluorescence spectra of the ligand H2bpb and the com-
plex are determined in the solid state under the same measure-
ment environment at room temperature on HITRCHI F-4500
Fluorophotometer. The fluorescence excitation spectra of the
Co(α) OH(Me)· · ·N(Py) and form into 1D chain by slantly
alternating bc plane (Figure 3). In 1D chains H2bpb ligands do
not parallel each other, which has a natural helicity. The solvate
molecules of methanol play an important linkage part in the self-
assembly process. Each ligand has four available NH and C=O
groups available for intermolecular hydrogen bonding. Those
1D chains then self-assemble through intermolecular hydrogen
bonds between carbonyl and amide groups (N(3)-H(3N)· · ·O(1)
ligand H2bpb (λmax = 244 nm ) and that of the complex (λmax
=
˚
= 2.8789(19) A) of adjacent molecules (Figure 4). Thus, in ir-
regular direction an intricate three-dimensional network comes
into being,[17] as shown in Figure 5.
Thermogravimetric Analysis (TG)
The thermal behavior of the complex under investigation
was studied using the thermogravimetry (TG) and the DSC
techniques. The DSC-TG curve of the complex (shown as in
Figure 6) was scanned in the range of 30–800◦C with argon
atmosphere on STA 409 PC Thermal Analyzer. The thermal an-
alytic data for initial complex show a first endothermic weight
loss of 7.09% between 157 and 187◦C with a DSC peak at 179◦C FIG. 8. The fluorescence emission spectra of ligand and the complex in solid
state.
which corresponds exactly (Calcd. 7.32%) to the release of two

544
P. ZHANG ET AL.
245 nm ) are illustrated in Figure 7. The emission spectra of the
ligand and the complex upon excitation at the isosbestic point
at 245 nm are plotted in Figure 8. Though the complex displays
an evidently higher luminescence strength than ligand H2bpb
(λmax = 389 nm), but models and positions of their peaks are
same, which is likely attributed to the charge transfer of intra-
ligand.
7. Hausmann, J. Jameson, G.B., and Brooker, S. Control of molecular
architecture by the degree of deprotonation: Self-assembled di- and tetranu-
clear copper(II) complexes of N,N-bis (2–pyridylmethyl) pyrazine-2,3-
dicarboxamide. Chem. Comm., 2003, 2992–2993.
8. (a) Mondal, A., Pariya, C., Chaudhuri, N.R., Nayak, N.P., Mukherjee,
A.K., and Ghosh, A. Syntheses of [Ni2(dien)2(NCS)4(H2O)] and
[Ni(aepn)(NCS)2]n ((dien = bis(2-aminoethyl)amine and aepn = N-(2-
aminoethyl)-1,3-propanediamine): Single crystal structure analysis and
thermal behaviour in the solid state. Polyhedron., 1997, 16, 39–45;
(b) Khan, A.A., Saxena, A.K., and Iftikhar, K. Mixed-ligand lan-
thanide complexes—X. Interaction of trivalent lanthanides with 1,10-
phenanthroline and thiocyanate in alcohol. Polyhedron., 1997, 16, 4143–
4151; (c) Goher, M.A.S., Alshatti, L.A., and Mautner, F.A. A poly-
meric complex of copper (II) bridged simultaneously by tridentate gly-
cinato and µ(N,S)-thiocyanato anions. Synthesis, spectral, structural and
thermal properties of the complex [Cu(Glycinato)(NCS)(H2O)]. Poly-
hedron., 1997, 16, 889–895; (d) Mukherjee, A.K., Koner, S., Ghosh,
A., Chaudhuri, N.R., Mukherjee, M., and Welch A.J. Isomerism in
bis(diethylenetriamine)nickel(II) thiocyanate: Synthesis, solid-state in-
terconversion and X-ray crystallographic study of sym-fac and mer
isomers. J. Chem. Soc., Dalton Trans., 1994, 16, 2367–2371; (e)
Matouzenko, G.S., Bousseksou, A., Lecocq, S., Vankoningsbruggen, P.J.,
Perrin, M., Kahn, O., and Collet. A. Spin transition in [Fe(DPEA)(NCS)2],
SUPPLEMENTARY MATERIAL
Crystallographic data for the structural analyses have been
deposited with the Cambridge Crystallographic Data Center,
CCDC Nos. 609946, for the complex. Copies of this in-
formation may be obtained free of charge from: The Di-
rector, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(fax: +44 1223 336033; E-mail: deposit@ccdc.cam.ac.uk or
www:hppt://www.ccdc.cam.ac.uk).
REFERENCES
1. (a) Tara, J.B., Dana, J.E., and Richard, J.P. Self-assembly using dy-
namic coordination chemistry and hydrogen bonding: Mercury(II) macro-
cycles, polymers and sheets. Inorg. Chem., 2004, 43, 5550–5557; (b)
Mehdi, A., Kurt, J.S., and Soraia, M. Synthesis and characterization of
trans-[Co(III)(bpb)(amine)2]X (X NCS, ClO4). X-ray crystal structure of
trans-[Co(III)(bpb)(pyrrolidine)2]NCS 0.5H2O containing intermolecular
a
compound with the new tetradentate ligand (2-aminoethyl)bis(2-
pyridylmethyl)amine (DPEA): Crystal structure, magnetic Proper-
ties, and Mo¨ssbauer spectroscopy. Inorg. Chem., 1997, 36, 2975–
2981.
9. Amirnasr, M., Schenk, K.J., and Meghdadi, S. Synthesis and character-
ization of trans-[Co(III)(bpb)(amine)2]X (X NCS, ClO4). X-ray crystal
structure of trans-[Co(III)(bpb)(pyrrolidine)2]NCS·0.5H2O containing in-
termolecular N H. . . O C hydrogen-bonding. Inorg. Chim. Acta., 2002,
338, 19–26.
10. Muthu, S., Yip, J.H.K., and Vittal, J.J. Coordination networks of Ag(I)
and N,N-bis(3-pyridinecarboxamide)-1,6-hexane: Structures and anion ex-
change. J. Chem. Soc., Dalton Trans., 2002, 4561–4568.
11. Qin, Z., Jennings, M.C., and Puddephatt, R.J. Self-assembly of polymer
and sheet structures from palladium (II) complexes by hydrogen bonding
between carboxamide substituents. Inorg. Chem., 2001, 40, 6220–6228.
12. Burchell, T.J., Eisler, D.J., Jennings, M.C., and Puddephatt, R.J. Ring-
opening polymerization of gold macrocycles and self-assembly of a co-
ordination polymer through hydrogen-bonding. Chem. Comm., 2003, 17,
2228–2229.
N-H
O C hydrogen-bonding. Inorg. Chim. Acta 2002, 338, 19–26; (c)
Lin, J., Tu, C., Lin, H., Jiang, P.J., Ding, J., and Guo, Z.J. Crystal structure
and superoxide dismutase activity of a six-coordinate manganese(III) com-
plex. Inorg. Chem. Comm., 2003, 6, 262–265; (d) Tara, J.B., Dana, J.E.,
Michael, C.J., and Richard, J. Puddephatt ring-opening polymerization of
gold macrocycles and self-assembly of a coordination polymer through
hydrogen-bonding. Chem. Comm., 2003, 2228–2229.
2. (a) Conlon, D.A., and Yasuda, N. Practical method for the rhodium-
catalyzed addition of aryl- and alkenylboronic acids to aldehydes. Adv.
Synth. Catal. 2001, 1, 343–350; (b) Trost, B.M., and Hachiya, I. Asymmet-
ric molybdenum-catalyzed alkylations. J. Am. Chem. Soc., 1998, 120 (5),
1104–1105.
3. (a) Collinson, R., Gelbrick, T., Hursthouse, M.B., and Tucker, J.H.R. Novel
ferrocene receptors for barbiturates and ureas. Chem. Commun. 2001, 555–
556; (b) Huc, I., Krische, M.J., Funeriu, D.P. and Lehn, J.M. Dynamic
combinatorial chemistry: Substrate H-bonding directed assembly of re-
ceptors based on bipyridine-metal complexes. Eur. J. Inorg. Chem., 1999,
1415.
13. Burchell, T.J., Eisler, D.J., and Puddephatt, R.J. Engineering silver (I) co-
ordination networks through hydrogen bonding. Chem. Comm., 2004, 944–
945.
14. Sheldrick, G.M. SHELXL93; University of Go¨ttingen: Go¨ttingen, Germany,
1993.
4. Epperson, D., Ming, L.J., Baker, G.R., and Newkome, G.R. Paramagnetic
cobalt(II) as an NMR probe of dendrimer structure: Mobility and coopera-
tivity of dendritic arms. J. Am. Chem. Soc., 2001, 123, 8583–8592.
5. Zhang, J.Y., Liu, Q., Duan, C.Y., Shao, Y., Ding, J., Miao, Z.H., You,
X.Z., and Guo, Z.J. Structural evidence for the facile chelate-ring opening
reactions of novel platinum(II)–pyridine carboxamide complexes. J. Chem.
Soc., Dalton Trans., 2002, 591–597.
6. Jain, S.L., Pravat, B., Milton, H.L., Alexandra, M.Z.S., Joe, A.C., and
Woollins, J.D. New pyridine carboxamide ligands and their complexation
to copper(II). X-Ray crystal structures of mono-, di, tri- and tetranuclear
copper complexes. Dalton Trans., 2004, 862–871.
15. Gudasi, K., Vadavi, R., Shenoy, R., Patil, M., Patil, S.A., and Nethaji,
M. Transition metal complexes of a tridentate ligand bearing two pendant
pyridine bases: The X-ray crystal structure of pentacoordinate copper(II)
complex. Inorg. Chim. Acta., 2005, 358, 3799–3806.
16. Wilson, J., and Rabindranath, M. Synthesis, structure, and properties of
monomeric Fe (II), Co (II), and Ni (II) complexes of neutral N-(aryl)-2-
pyridinecarboxamides. Inorg. Chim. Acta., 2006, 359, 4565–4573.
17. Burchell, T.J., Eisler, D.J., and Puddephatt, R.J. Self-assembly using dy-
namic coordination chemistry and hydrogen bonding: Mercury(II) macro-
cycles, polymers and sheets. Inorg. Chem. 2004, 43, 5550–5557.