Synthesis and characterization of nickel(II) complexes of benzoic acid and methyl substituted benzoic acid hydrazides and x-ray structure of Ni[C6H5CONHNH2]3Cl 2·3CH3OH

Article abstract of DOI:10.1081/SIM-120017781

Nickel(II) complexes of benzoic acid hydrazides (BAH) and o, m, and p-substituted methylbenzoic acid hydrazides (MBAH) have been prepared and characterized by elemental analysis, room temperature magnetic susceptibility measurements, infrared and electronic reflectance spectral studies. The biological activities of the compounds and x-ray structure of Ni[C₆H₅CONHNH₂]₃Cl ₂·3CH₃OH are also reported. The microanalyses showed that the hydrazides reacted with the nickel(II) salts in 1:3 (metal:ligand) molar ratio. The hydrazide ligand behaves as a neutral bidentate chelating ligand with coordination involving the carbonyl oxygen and the amino nitrogen of the hydrazide moiety. The effective magnetic moments (μ_eff), infrared and electronic spectra of the compounds are consistent with a six-coordinate pseudo-octahedral arrangement of the ligands around the nickel ion. The x-ray diffraction analysis of Ni[C₆H₅CONHNH₂]₃Cl ₂·3CH₃OH showed that it crystallizes as a triclinic system with a P-1 space group, a=10.2289(5), b=12.0707(6), c=14.0477(7) A, α=67.5540(10)°, β=69.2360(10)°, γ=73.7860(10)°. The nickel ion is coordinated by three units of benzoic acid hydrazide with the chloride ions and the methanol solvates uncoordinated in the crystal lattice. The compounds show some measurable activity against selected bacteria and fungi.

Full text of DOI:10.1081/SIM-120017781

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Synthesis and Characterization of Nickel(II)
Complexes of Benzoic Acid and Methyl Substituted
Benzoic Acid Hydrazides and X‐Ray Structure of
Ni[C6H5CONHNH2]3Cl2·3CH3OH
O. A. Odunola a , I. O. Adeoye b , J.A. O. Woods b & A. C. Gelebe a
a Department of Chemistry , University of the North , Private Bag X1106, Sovenga, 0727,
South Africa
b Department of Chemistry , University of Ibadan , Ibadan, Nigeria
Published online: 09 Dec 2011.
To cite this article: O. A. Odunola , I. O. Adeoye , J.A. O. Woods & A. C. Gelebe (2003) Synthesis and Characterization
of Nickel(II) Complexes of Benzoic Acid and Methyl Substituted Benzoic Acid Hydrazides and X‐Ray Structure of
Ni[C6H5CONHNH2]3Cl2·3CH3OH, Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 33:2, 205-221, DOI:
10.1081/SIM-120017781
To link to this article: http://dx.doi.org/10.1081/SIM-120017781
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SYNTHESIS AND REACTIVITY IN INORGANIC AND METAL-ORGANIC CHEMISTRY
Vol. 33, No. 2, pp. 205–221, 2003
Synthesis and Characterization of Nickel(II)
Complexes of Benzoic Acid and Methyl Substituted
Benzoic Acid Hydrazides and X-Ray Structure of
Ni[C H CONHNH ] Cl 3CH OH
6
2ꢀ
5
2 3
3
O. A. Odunola,1, I. O. Adeoye, J. A. O. Woods,
2
2
*
and A. C. Gelebe1
1Department of Chemistry, University of the North,
Sovenga, South Africa
2Department of Chemistry, University of Ibadan, Ibadan, Nigeria
ABSTRACT
Nickel(II) complexes of benzoic acid hydrazides (BAH) and o, m, and
p-substituted methylbenzoic acid hydrazides (MBAH) have been pre-
pared and characterized by elemental analysis, room temperature mag-
netic susceptibility measurements, infrared and electronic reflectance
spectral studies. The biological activities of the compounds and x-ray
structure of Ni[C6H5CONHNH2]3Cl2ꢀ3CH3OH are also reported. The
microanalyses showed that the hydrazides reacted with the nickel(II)
salts in 1:3 (metal:ligand) molar ratio. The hydrazide ligand behaves as a
*
Correspondence: O. A. Odunola, Department of Chemistry, University of the
North, Private Bag X1106, Sovenga 0727, South Africa; E-mail: odunolao@unin.
unorth.ac.za.
205
DOI: 10.1081/SIM-120017781
0094-5714 (Print); 1532-2440 (Online)
www.dekker.com
Copyright D 2003 by Marcel Dekker, Inc.

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206
Odunola et al.
neutral bidentate chelating ligand with coordination involving the car-
bonyl oxygen and the amino nitrogen of the hydrazide moiety. The
effective magnetic moments (meff), infrared and electronic spectra of the
compounds are consistent with a six-coordinate pseudo-octahedral ar-
rangement of the ligands around the nickel ion. The x-ray diffraction
analysis of Ni[C6H5CONHNH2]3Cl2ꢀ3CH3OH showed that it crystallizes
as a triclinic system with a P-1 space group, a = 10.2289(5),
˚
b = 12.0707(6), c = 14.0477(7) A, a = 67.5540(10)ꢀ, b = 69.2360(10)ꢀ,
g = 73.7860(10)ꢀ. The nickel ion is coordinated by three units of benzoic
acid hydrazide with the chloride ions and the methanol solvates
uncoordinated in the crystal lattice. The compounds show some
measurable activity against selected bacteria and fungi.
Key Words: Nickel; Hydrazides; Magnetic; Infrared; Electronic;
X-ray; Microbiology.
INTRODUCTION
The success of cis-diamminedichloroplatinum(II) (cis-platin) in clinical
oncology not only stimulated interests in activities of platinum complexes
using various bioligands; but also the screening of biological activities of
various transition metal complexes.[1–5] Hydrazides and its derivatives
have been known to display antitubercular, antitumour and antimicrobial
activities.[6–9] Carboxylic acid hydrazides have equally been used in polymer
stabilization, metal extractants and in solving ion-exchange problems.[10–14]
However, there exists a scarcity structural data and structure activity rela-
tionship of hydrazides especially for their coordination compounds, and the
question of the participation of the metal anion in coordination has not been
satisfactorily addressed.[14–16] Gad et al.[14] in their study of poly-acryloyl
benzoic acid hydrazides with some transition metals including copper(II)
and nickel(II) reported coordination of chloride ions to some of these metals.
In our previous studies on this system, the x-ray structure of Cu[C6H5-
COO]2(NO3)2 showed that nitrate anions are uncoordinated but remain in the
crystal lattice.[17] It has also been established that coordination compounds
exhibit a greater biological activity than the ligands themselves.[18,19]
In the present study, we present our report on the synthesis, spectral,
biological and magnetic properties of nickel(II) complexes of benzoic acid
hydrazides (BAH) and ortho-methylbenzoic acid hydrazide (o-MBAH),
meta-methylbenzoic acid hydrazide (m-MBAH) and para-methylbenzoic
acid hydrazide (p-MBAH). The nickel(II) complexes of BAH and MBAH
are new and are reported here for the first time. Although, the preparation
and electronic spectra of Ni[C6H5COO]3Cl2 have been previously re-

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Nickel(II) Complexes
207
ported,[16] we have obtained another composition of the compound
{Ni[C6H5COO]3Cl2ꢀ3CH3OH} with methanol as solvate and determined
its crystal structure.
EXPERIMENTAL
Reagents and Solvents
Reagent grade NiSO4ꢀ6H2O, NiCl2ꢀ6H2O, Ni(NO3)2ꢀ6H2O, Ni(CH3-
COO)2ꢀ4H2O, methyl benzoate, ortho-, meta-, and para-methyl substituted
benzoic acids were purchased from Aldrich and used as received. Solvents
used were of the reagent grade or purer.
Preparation of the Ligands
Benzoic acid hydrazides [BAH], ortho-, meta-, and para-substituted
methylbenzoic acid hydrazides were prepared as previously reported.[17]
The purity and composition of the compounds were however established by
elemental analyses, gas chromatography-mass spectrometry (GC-MS) and
melting points.
Synthesis of the Complexes
Preparation of Ni[BAH]3Cl2ꢀ3CH3OH
NiCl2ꢀ6H2O (2.38 g, 10 mmols) dissolved in 15 mL hot 50% methanol
was added drop-wise to 40 mL of a stirred solution of benzoic acid
hydrazide (2.72 g, 20 mmols) in a 100 mL beaker maintained at 40 ꢀC for 1
hour. During stirring, the green coloured solution gradually turned blue.
The precipitates formed were filtered by suction, washed with water and
methanol and then recrystallized in methanol and left at ambient tem-
perature. A crystal suitable for X-ray measurement was found in the
mother liquor. The same procedure was used to prepare Ni[BAH]3SO4,
Ni[BAH]3(NO3)2 and Ni[BAH]3(CH3COO)2.
Preparation of Ni[o-MBAH]3SO4
NiSO4ꢀ6H2O (1.31 g, 5.0 mmols) dissolved in 15 mL of 30% methanol
was added drop-wise to 30 mL of a hot methanolic solution of o-MBAH

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208
Odunola et al.
(2.25 g, 15 mmols) in a 100 mL beaker while stirring at 40 ꢀC. The volume of
the mixture was reduced by one third and the mixture transferred to a 100 mL
Buchner flask equipped with a condenser and stirring continued for about 2 h.
The precipitates formed were filtered, washed with water and methanol and
dried in vacuo over anhydrous calcium chloride. The nickel(II) chloride,
nitrate and acetate derivatives were prepared similarly.
Physical Measurements
The percent nickel in the complexes was determined using a com-
plexometric method[20] while the elemental analyses for C, H, and N were
determined using a Perkin–Elmer Series II 2400 CHNS/O analyzer. The
infrared spectra were recorded on a Perkin–Elmer FTIR Spectrum 1000
spectrometer using KBr discs between 350–4000 cm ꢁ 1. Frequencies are
believed to be accurate to 2 cm ꢁ 1. Electronic reflectance spectra of the
ligands and the complexes in Nujol mulls were recorded on a Varian Cary
1E spectrophotometer between 190–900 nm. Melting points of the com-
pounds were determined using a Buchi B-540 melting point apparatus.
Magnetic susceptibilities were measured on powdered samples at room
temperature using the Gouy method; calibration was done using mercury-
tetrathiocyanatocobaltate(II) and diamagnetic corrections were calculated
using Pascal’s constants.[21] All the compounds were dried inside a vacuum
pistol over P2O5 at 110 ꢀC for a period between 1–2 hours.
Experimental Details and Crystal Data
for Ni[BAH]3Cl2ꢀ3CH3OH
A single crystal removed from a methanolic solution of tris(benzoic
acid hydrazide)nickel(II) chloride with dimensions 0.340 ꢂ 0.255 ꢂ 0.187
mm was used for the x-ray measurement. The data sets were collected on
a Siemens SMART CCD diffractometer (1.63 ꢃ q ꢃ 22.50 ꢀ) employing
monochromated X-radiation (l=0.71073), MoKa, o scans, T =173(2) K.
A total of 3839 unique reflections were observed with I >2.0s(I) out
of 8879 measured reflections. The data were corrected for Lorentz and
polarization effects but not for absorption. The crystal parameters are
as follows: C24H36Cl2N6NiO6, M=634.20; triclinic, space group P-1,
3
a =10.2289(5), b= 12.0707(6), c =14.0477(7) A, V =1478.03(13) A ,
˚
˚
a= 67.5540(10) ꢀ, b = 69.2360(10) ꢀ, g =73.7860 (10) ꢀ, Z =2, rcalc =1.425
M g m ꢁ 3
.
The structure was solved by a direct method (SHELXS-97) and refined
by a full-matrix least squares procedures based on F2 (SHELXL-97).[22]

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Nickel(II) Complexes
209
Non-hydrogen atoms were refined with anisotropic displacement parameters.
The coordinates of the H atoms were calculated by the SHELXL program
using an appropriate riding model with varied thermal parameters.
Scattering factors for atoms were taken from the International Table for
Crystallography, Vol. III.[23] The refinement converged at a final R= 0.0412,
wR2 = 0.1012, GOF = 0.246. The maximum and minimum electron density
ꢁ 3
˚
peaks in the final difference map were 0.317 and ꢁ 0.370 e.A
,
respectively. All calculations were performed on a Silicon Graphics Indigo
2 workstation.
The Cambridge Crystallographic Data Centre (CCDC) 182717 contains
the supplementary crystallographic data for this paper. These data can be
obtained free of charge via (or from the CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: + 44 1223 336033; e-mail: deposit@ccdc.
cam.ac.uk).
Antimicrobial Activity
The disk diffusion method was used to investigate the antimicrobial
activity of the ligands and complexes as previously reported.[17] The com-
pounds were tested against the following bacteria: Staphylococcus aureus,
Klebsiella pneumoniae, Klebsiella edwardsiella, Streptococcus faecalis,
Bacillus cereus, Botridiplodia spp. and fungi: Rhizopus oligoporous, Asper-
gillus flavae and Candida albicans.
RESULTS AND DISCUSSION
The formation of benzoic acid hydrazides and the methyl substituted
benzoic acid hydrazides proceeded in respectable yields (58–64%) from
their respective methyl benzoate esters and anhydrous hydrazine as given in
Eqs. 1 and 2.
C6H5COOCH3 þ H2NNH2 ! C6H5CONHNH2 þ CH3OH
ð1Þ
ðo; m; pÞ-CH3C6H4COOCH3 þ H2NNH2
! ðo; m; pÞ-CH3C6H4CONHNH2 þ CH3OH
ð2Þ
The analytical data and room temperature effective magnetic moments
(meff) for the complexes are given in Table 1. The reaction of the metal salts

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210
Odunola et al.

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Nickel(II) Complexes
211

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212
Odunola et al.
and the respective ligands to form the complexes can be represented as
shown in Eqs. 3 and 4.
NiX2ꢀxH2O þ 3C6H5CONHNH2
! Ni½C6H5CONHNH2ꢄ3X2 þ xH2O
ð3Þ
ð4Þ
NiX2ꢀxH2O þ 3z-CH3C6H4CONHNH2
! Ni½CH3C6H4CONHNH2ꢄ3X2 þ xH2O
where X =Cl, NO3, CH3COO, or 1/2 SO4; z= ortho-, meta-, or para.
The complexes were obtained as solids of various shades of green and
blue. The nickel(II) complexes of benzoic acid hydrazides are fairly
soluble in protic solvents like methanol and ethanol while those of the
methyl substituted complexes display very poor solubility just like their
copper(II) analogues.
Infrared Spectra
The principal infrared bands and electronic reflectance spectra of
the complexes in Nujol mulls are presented in Table 2. The spectral
assignments have been done by critically comparing the spectra of the
ligands with those of the complexes. The features observed in the infrared
spectra are consistent with the structural patterns of the compounds.[24,25]
Three related vibrations have been successfully used to infer coordination
of ligands to the metal in the spectra of hydrazides and its metal com-
plexes.[4,16,17,19] These are the carbonyl stretching mode n(C=O), referred
to as ‘‘amide I’’ band, the coupling between the in-plane bending d(N–H)
and n(C–N) stretching, referred to as ‘‘amide II’’ band and the stretching
frequency for the amino group n(NH2). The asymmetric nas(NH2) and the
symmetric ns(NH2) stretching vibrations for the amino group observed as
two separate bands in the ligands between 3300–3310 cm ꢁ 1 overlap in
most of the metal complexes and were shifted to lower frequency at 3280–
3164 cm ꢁ 1. This indicates the participation of the NH2 group in coor-
dination to the nickel(II) ion. The assignment and interpretations of the
vibrations of the complexes below 1700 cm ꢁ 1 are difficult to make with
certainty, because of the absorptions of the aromatic nucleus in the interval
1610–1320 cm ꢁ 1 and the differing assignments that have been made in
this region.[4,5,14,19] However, since the aromatic nucleus exert relatively
low influence on coordination, the vibration between 1662–1630 cm ꢁ 1 in

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Nickel(II) Complexes
213

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214
Odunola et al.
the ligands are assigned to the ‘‘amide I’’ band. These vibrations appeared
in the nickel(II) complexes at a lower frequency region at 1655–1616
cm ꢁ 1 suggesting the coordination of n(C =O) to
the nickel ion. The
‘‘amide II’’ bands in the ligands and complexes appeared in the region
between 1580–1570 and 1575–1540 cm ꢁ 1, respectively. Although this
vibration has been noted in previous studies not to be sensitive to
coordination by metals[14–16,19], there appears to be a general lowering in
the frequency of this band on coordination in the complexes studied with
the exception of Ni[BAH]3(CH3COO)2. The deformation bands d(NH2)
between 1603–1608 cm ꢁ 1, t(NH2) between 1400–1300 cm ꢁ 1, g(NH2)
between 1040–1030 cm ꢁ 1 and d(HNN) atꢅ 1240 cm ꢁ 1 do not experience
significant shifts in the spectra of the complexes because of the absence of
H-bonds between C =O and NH2.[19] Other metal-ligand and ligand
related vibrations are observed below 600 cm ꢁ 1
.
Electronic Spectra
The electronic reflectance spectra of the ligands in the UV region have
similar pattern and display single bands between 41,500–40,980 cm ꢁ 1
except for BAH where an additional shoulder was observed at
ꢅ 37,880 cm ꢁ 1. In the complexes, these bands are shifted to the 48,540–
40,320 cmꢁ 1 range and there appears in some cases an additional band or
shoulder in the region 38,610–34,970 cm ꢁ 1. These bands are assigned to
the p !p* transition in the aromatic system overlapping with the p !p*
transition in the carbonyl group. These changes show a significant p !p*
interactions in the complexes. It can also be correlated with the involve-
ment of N and O atoms from the ligand in coordination which strengthens
the C = O and the –NH2 bonds involved in the charge transfer process.[19]
The appearance of the band in the 38,610–34,970 cm ꢁ 1 range has been
observed in previous studies on similar system and attributed to the p! n
transitions in the carbonyl group.[19,26]
The visible spectra of the nickel(II) complexes studied display
transitions in the ranges 13,120–11,120, 21,230–16,780 and 27,620–
26,740 cm ꢁ 1. These transitions have been assigned to A2g(F) ! T2g(F)-
3
3
3
3
3
3
(n1), A2g(F) ! T1g(F) (n2) and A2g(F) ! T1g(P) (n3) transitions, respect-
3
3
ively. Splitting of the A2g(F) ! T1g(F) transition was observed in some of
the compounds. The observed transitions at 16,860 and 13,200 cm ꢁ 1 for
Ni[BAH]3Cl2ꢀ3CH3OH compare favourably well with the Nujol mull
spectra of Ni[C6H5COO]3Cl2 at 17,857 and 13,333 cm ꢁ 1, respectively. In
the latter complex, an additional band was observed at ꢅ 10,500 cm ꢁ 1
in various solvents; this could not be observed in our complex due to

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Nickel(II) Complexes
215
instrumental limitations. Generally, the crystal field spectra of regular
octahedral complexes are characterized by the presence of three moderately
strong bands and the ratio n2/n1, the frequencies of the first and second
band maxima,[27,28] lies in most cases between 1.5–1.7. The complexes
displaying these two bands among those studied have this ratio observed
between 1.41–1.51, suggesting the octahedral arrangement of ligands
around the nickel(II) ion. The lower values obtained for this ratio is not
unusual, even for octahedral nickel(II) complexes that have been struc-
turally characterized, and indicates the degree of distortion of the com-
pounds from the ‘ideal’ geometry.[29,30] In principle, it should be easy to
3
deduce 10Dq =E[3A2g ! T2g] from the spectra of the complexes. However,
3
3
3
1
since the A2g ! T2g and A2g ! Eg transitions are not well separated in
the spectra, it is not possible to determine 10Dq accurately.[31]
Magnetic Moments
The effective magnetic moments (meff) of nickel(II) complexes in a
cubic field range between 2.8–4.2 B.M. The deviation from the expected
spin-only (ms.o.) value of 2.83 B.M. for two unpaired electrons are generally
attributed to orbital contributions to the magnetic moments. Four-
coordinated tetrahedral nickel(II) complexes have higher meff values (3.2–
4.1 B.M.) compared to the octahedral complexes (2.9–3.3 B.M.).[32] The
measured values of 2.77–3.20 B.M. in the present complexes falls in the
range expected for six-coordinate octahedral nickel(II). Generally, the
moments of nickel(II) complexes of benzoic acid hydrazides appear slightly
higher (3.05–3.15 B.M.) than those of the methyl substituted analogues
(2.85–3.10 B.M.) suggesting some sort of interactions of the latter in the
solid state. The position of the methyl substituents does not appear to have
any influence on the magnitude of the moments.
Crystal Structures for Ni[BAH]3Cl2ꢀ3CH3OH
The ORTEP representation of the structure of Ni[BAH]3Cl2ꢀ3CH3OH
is shown in Figure 1, together with the atomic numbering scheme. In-
teratomic distances and angles relevant to the coordination sphere around
nickel are given in Table 3. The molecular structure consists of a
mononuclear, six-coordinated nickel(II) complexed by three units of ben-
zoic acid hydrazides. The coordination to the metal is through the carbonyl
oxygen of the amide and the nitrogen of the amino group of each unit of
the hydrazide to give essentially a NiN3O3 chromophore. The two chloride
ions and three molecules of methanol are held within the interstitial spaces

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216
Odunola et al.
Figure 1. ORTEP representation of the structure of Ni[BAH]3Cl2ꢀ3CH3OH.
Ellipsoids are drawn at 50% probability and protons are omitted for clarity.
of the crystal lattice. The C–O bond distances for the solvent molecules
˚
have different values; 1.367(7), 1.427 and 1.404 A for O(4)–C(22), O(5)–
C(23) and O(6)–C(24), respectively; which may indicate some measure of
interaction of the solvent molecules with the monomeric complex in the
crystal lattice. The geometry around the nickel(II) is best described as
distorted octahedral with similarity in the bite angles; O(1)–Ni(1)–N(1)
and O(2)–Ni(1)–N(3) have the same value of 78 ꢀ while O(3)–Ni(1)–N(5)
is 79 ꢀ. These angles are particularly distorted from the ‘ideal’ octahedral
value of 90 ꢀ probably due to chelate compression arising from the ar-
rangement of three hydrazide units around the nickel ion. Similarly, this
degree of distortion is also indicated by the trans octahedral angles,
169.23(15), 171.10(14), and 171.10(14) for O(3)–Ni(1)–N(3), O(2)–
Ni(1)–(N1), and O(1)–Ni(1)–N(5) respectively, which, show a deviation
of less than 12 ꢀ from the ‘ideal’ value which should be 180 ꢀ for this
˚
˚
stereochemistry. The Ni–O (2.046–2.049 A) and Ni–N (2.078–2.099 A)
bond distances in the compounds are crystallographically identical and
are not unusual but compare favourably with bond distances for six-
coordinate octahedral nickel(II) complexes that have been structurally

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Nickel(II) Complexes
217
Table 3. Selected bond distances and angles for Ni[BAH]3Cl2ꢀ3CH3OH.
˚
Bond distances (A)
Bond angles ( ꢀ)
Ni(1)–O(3)
2.046(3)
2.048(3)
2.049(3)
2.078(4)
2.099(4)
2.105(4)
1.246(5)
1.238(5)
1.250(5)
1.427(7)
1.404(7)
1.367(7)
1.352(6)
1.490(7)
1.362(7)
1.345(6)
1.331(6)
1.367(7)
1.404(5)
1.420(5)
1.432(5)
O(3)–Ni(1)–O(2)
92.65(13)
91.94(13)
89.10(13)
169.23(15)
79.47(14)
95.23(14)
89.06(14)
167.11(15)
78.07(15)
100.26(15)
79.18(14)
90.59(15)
171.10(14)
93.46(16)
102.28(16)
114.0(3)
Ni(1)–O(2)
Ni(1)–O(1)
Ni(1)–N(3)
Ni(1)–N(1)
Ni(1)–N(5)
O(1)–C(1)
O(2)–C(8)
O(3)–C(15)
O(4)–C(22)
O(5)–C(23)
O(6)–C(24)#1
C(1)–N(2)
C(1)–C(2)
C(2)–C(7)
C(8)–N(4)
C(15)–N(6)
C(24)–O(6)#2
N(1)–N(2)
N(3)–N(4)
N(5)–N(6)
O(3)–Ni(1)–O(1)
O(2)–Ni(1)–O(1)
O(3)–Ni(1)–N(3)
O(2)–Ni(1)–N(3)
O(1)–Ni(1)–N(3)
O(3)–Ni(1)–N(1)
O(2)–Ni(1)–N(1)
O(1)–Ni(1)–N(1)
N(3)–Ni(1)–N(1)
O(3)–Ni(1)–N(5)
O(2)–Ni(1)–N(5)
O(1)–Ni(1)–N(5)
N(3)–Ni(1)–N(5)
N(1)–Ni(1)–N(5)
C(1)–O(1)–Ni(1)
C(8)–O(2)–Ni(1)
C(15)–O(3)–Ni(1)
O(1)–C(1)–N(2)
O(2)–C(8)–N(4)
O(3)–C(15)–N(6)
N(2)–N(1)–Ni(1)
C(1)–N(2)–N(1)
N(4)–N(3)–Ni(1)
C(8)–N(4)–N(3)
N(6)–N(5)–Ni(1)
113.5(3)
114.5(3)
119.6(5)
121.1(5)
121.4(5)
108.0(3)
117.1(4)
107.7(3)
116.9(4)
107.7(3)
Symmetry codes (#)—x, y, z.
characterized.[26,29,33] These bond distances are shorter when compared with
˚
an average of 2.152 and 2.276 A for Ni–O and Ni–N distances, res-
pectively, in a hydrazonic nickel(II) complex [Ni(H2dapo)(OH2)2]Cl2
{dapo 2,6-diacetylpyridinebis(octanoylhydrazone)}, a seven coordinate
pentagonal-bipyramidal compound.
Microbiology
The nickel(II) complexes tested showed some measurable activities
against the tested bacteria and fungi, however, they cannot be considered
significant compared to those previously reported on similar systems.[7,9] It
seems the activities of the hydrazide compounds are more enhanced when

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218
Odunola et al.
Figure 2. Suggested structure of the complexes.
coupled with organic groups such as oxadiazolines, furyl, thiazolidinones,
and imidazoles.[7,9,34]
CONCLUSION
Benzoic acid hydrazide (BAH) and substituted methylbenzoic acid
hydrazides coordinate to nickel(II) using the C =O and the NH2 groups of
the hydrazides as confirmed from a comparison of the spectra of the ligands
and complexes. The elemental analyses, spectral and magnetic susceptibility
studies confirm a six-coordinated, distorted-octahedral arrangements of the
ligands around the nickel(II) ion. There is no evidence for the coordination
of the metal anions in the compound. While the compounds show some
measurable activities against the tested bacteria, these activities cannot be
termed significant compared to similar compounds earlier reported.[9,34] An
octahedral configuration for the complexes (Figure 2) is thereby suggested
similar to the crystal structure of Ni[BAH]3Cl2ꢀ3CH3OH with the anions
uncoordinated in the crystal lattice.
ACKNOWLEDGMENTS
This work was supported by the University of the North in the form of
a Senate Research Grant 1881. An extended leave of absence for OAO

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Nickel(II) Complexes
219
from Ladoke Akintola University of Technology, Ogbomoso, Nigeria, is
also gratefully acknowledged.
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Received May 10, 2002
Accepted September 16, 2002
Referee I: S. Chellama
Referee II: G. O. Carlisle