New cobalt(II) and nickel(II) complexes of 2-hydroxy-benzyl derivatives of 4-aminoantipyrine

Article abstract of DOI:10.1016/j.poly.2012.06.061

The complexes [Co(HL²)₂]·H ₂O·3CH₃OH (3), [Ni(HL¹) ₂]·4H₂O·CH₃OH (4) and [Ni(HL ²)₂]·4H₂O·CH₃OH (5) with 4-((2-hydroxybenzy

Full text of DOI:10.1016/j.poly.2012.06.061

Polyhedron 44 (2012) 72–76
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Polyhedron
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New cobalt(II) and nickel(II) complexes of 2-hydroxy-benzyl derivatives
of 4-aminoantipyrine
b
b
Perizad A. Fatullayeva a, Ajdar A. Medjidov a, , Abel M. Maharramov , Atash V. Gurbanov ,
Rizvan K. Askerov b, Karim Q. Rahimov a, Maximilian N. Kopylovich c, Kamran T. Mahmudov b,c,
Armando J.L. Pombeiro c
⇑
⇑
,
a Institute of Chemical Problems of Azerbaijan Academy of Sciences, H.Cavid Str. 29, Az 1143 Baku, Azerbaijan
b Department of Chemistry, Baku State University, Z. Xalilov Str. 23, Az 1148 Baku, Azerbaijan
c Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
a r t i c l e i n f o
a b s t r a c t
The complexes [Co(HL2)2]ÁH2OÁ3CH3OH (3), [Ni(HL1)2]Á4H2OÁCH3OH (4) and [Ni(HL2)2]Á4H2OÁCH3OH (5)
with 4-((2-hydroxybenzyl)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (H2L1, 1) and 4-((5-
bromo-2-hydroxybenzyl)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (H2L2, 2) ligands were
synthesized and characterized by elemental analysis, ESI-MS, IR spectroscopy and X-ray single-crystal
analysis. Compounds 1 and 2 were prepared by the Schiff condensation of 4-aminoantipyrine and salicyl-
aldehyde or its 5-bromo-derivative with subsequent reduction. 1 and 2 were characterized by elemental
analysis, ESI-MS, IR, 1H and 13C NMR spectroscopies. All the complexes 3–5 have a metal-to-ligand ratio
of 1:2, the ligands being coordinated in the ONO mode, while the Co(II) and Ni(II) ions display a distorted
octahedral geometry. In the solid state, 3–5 are arranged as 1D supramolecular chains through H-bonded
water–methanol clusters placed in the voids of the metal-organic units.
Article history:
Received 9 April 2012
Accepted 11 June 2012
Available online 3 July 2012
Keywords:
4-Aminoantipyrine
Schiff condensation with reduction
Cobalt(II) and nickel(II) complexes
X-ray structural analysis
Crown Copyright Ó 2012 Published by Elsevier Ltd. All rights reserved.
1. Introduction
N
Schiff bases of 4-aminoantipyrine (hereafter denoted as SBA,
Scheme 1) and their complexes have attracted attention over the
past decades, not only due to their relatively easy synthesis, but
also in view of their potential biological, pharmacological and ana-
lytical applications [1–14]. In spite of the high interest, only few of
the SBA coordination compounds have been characterized struc-
turally; the reported examples include CuII [15–17], ZnII [18], FeII
[15] and CoII [18] complexes of different nuclearities and topolo-
gies, with the SBA ligands usually coordinating through the imine
nitrogen and carbonyl oxygen. Moreover, the flexibility, stability
and, as a consequence, the coordination ability of the SBA ligands
can be significantly enhanced by reduction of the C=N imine bond
[19] and introduction of additional functionalities, e.g. hydroxy-
benzo- ones. As result, upon complexation the ligands can form
stable fused five- and six-membered metallocycles, leading to pre-
dictable coordination (see below).
NH2
N
O
Scheme 1. 4-Aminoantipyrine.
has been performed towards the creation of new supramolecular
architectures [20,21] which are of particular interest as models
for various biological assemblies [22]. For example, several copper
complexes with ligands formed by the Schiff condensation of sali-
cylaldehyde and amino acids with subsequent reduction were ex-
plored as models of catalytic centres for enzymatic racemization
and transamination [23].
Thus, we believe that the synthesis of new complexes with deriv-
atives of 4-aminoantipyrine as ligands and their structural charac-
terization is interesting at least for some of the above mentioned
applications, and hence we focused this work on the following aims:
(i) to synthesize 4-((2-hydroxybenzyl)amino)-1,5-dimethyl-2-phe-
nyl-1H-pyrazol-3(2H)-one (H2L1, 1) and 4-((5-bromo-2-hydroxy-
benzyl)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (H2L2,
On the other hand, the engineering of networks by divergent
polydentate ligand–metal blocks united through solvent molecules
⇑
Corresponding authors.
E-mail addresses: ajdarmen@yahoo.com (A.A. Medjidov), kamran_chem@mail.
ru, kamran_chem@yahoo.com (K.T. Mahmudov).
0277-5387/$ - see front matter Crown Copyright Ó 2012 Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.06.061

P.A. Fatullayeva et al. / Polyhedron 44 (2012) 72–76
73
2); (ii) to prepare CoII and NiII complexes with the H2L1,2 ligands and
shed light on their structural details.
cation. After ca. 1 h H2L1,2 was separated by filtration and recrystal-
lized from methanol.
H2L1 (1): yield, 84% (based on 4-aminoantipyrine), soluble in
methanol, ethanol and acetone. Anal. Calc. for
(M = 309.15): C, 69.88; H, 6.19; N, 13.58. Found: C, 69.92; H,
6.30; N, 13.62%. IR, cmÀ1: 3360
(OH), 3341 (NH), 1630 (C=O).
C18H19N3O2
2. Experimental
m
m
m
2.1. Materials and instrumentation
ESI-MS: m/z: 310 [M+H]+. 1H NMR in DMSO-d6, d (ppm): 2.42 (s,
3H, CCH3), 3.15 (s, 3H, NCH3), 4.23 (m, 2H, CH2), 6.68–7.76 (9H,
ArÀH), 13.11 (s, 1H, OÀH), 11.08 (s, 1H, NÀH). 13C-{1H} NMR in
DMSO-d6, d (ppm): 16.3 (CH3), 31.2 (CH3), 45.7 (CH2), 115.1,
121.4, 123.9, 122.8, 128.4, 128.7, 129.8 (ArÀH), 130.8 (ArÀCH2),
132.5 (CpyNH), 133.5 (CpyCH3), 135.9 (CArNpy), 146.5 (ArÀOH),
160.7 (C=O).
All the chemicals were obtained from commercial sources
(Aldrich) and were used as received. Infrared spectra
(4000–400 cmÀ1) were recorded on a BIO-RAD FTS 3000MX instru-
ment in KBr pellets. The 1H and 13C NMR spectra were performed
at room temperature on a Bruker Avance II + 300 (UltraShield™
Magnet) spectrometer operating at 300.130 and 75.468 MHz for
proton and carbon-13, respectively. The chemical shifts are re-
ported in ppm using tetramethylsilane as the internal reference.
The acidity of the solutions was measured using a CG825 pH-meter
with an ESL-43-07 glass electrode adjusted by standard buffer
solutions and an EVL-1M3.1 silver-silver chloride reference elec-
trode. Electrospray mass spectra were run with an ion-trap instru-
ment (Varian 500-MS LC Ion Trap Mass Spectrometer) equipped
with an electrospray (ESI) ion source. For electrospray ionization,
the drying gas and flow rate were optimized according to the par-
ticular sample with 35 p.s.i. nebulizer pressure. Scanning was per-
formed from m/z 100 to 1200 in methanol solution. The
compounds were observed in the positive mode (capillary volt-
age = 80–105 V).
H2L2 (2): yield, 80% (based on 4-aminoantipyrine), soluble in
methanol, ethanol and acetone. Anal. Calc. for C18H18BrN3O2
(M = 387.06): C, 55.68; H, 4.67; N, 10.82. Found: C, 55.75; H,
4.57; N, 10.46%. IR, cmÀ1: 3480
m(OH), 3184 m(NH), 1638 m(C=O).
ESI-MS: m/z: 388 [M+H]+. 1H NMR in DMSO-d6, d (ppm): 2.46 (s,
3H, CCH3), 3.18 (s, 3H, NCH3), 4.31 (m, 2H, CH2), 6.55–7.47 (8H,
ArÀH), 12.94 (s, 1H, OÀH), 11.42 (s, 1H, NÀH). 13C-{1H} NMR in
DMSO-d6, d (ppm): 16.5 (CH3), 31.5 (CH3), 45.8 (CH2), 112.3
(ArÀBr), 119.2, 120.1, 122.7, 127.5, 127.8, 129.1 (ArÀH), 131.0
(ArÀCH2), 133.1 (CpyNH), 133.4 (CpyCH3), 134.8 (CArNpy), 146.2
(ArÀOH), 161.0 (C=O).
2.3. Preparation of the complexes [Co(HL2)2]ÁH2OÁ3CH3OH (3),
[Ni(HL1)2]Á4H2OÁCH3OH (4) and [Ni(HL2)2]Á4H2OÁCH3OH (5)
2.2. Synthesis of H2L1,2
To 50 mL of an ethanol–water (1:1 v/v) solution of H2L1,2
(0.2 mmol), 0.2 mmol NaOH was added under continuous stirring.
After 5 min, 0.1 mmol CoSO4Á7H2O (or NiSO4Á7H2O in the case of 4
and 5) was added. The mixture was stirred under solvent refluxing
for 5 min and then left for slow solvent evaporation. Light brown
(3), dark brown (4) or light blue (5) crystals of the complexes
started to form after ca 2 days, and after 5 d they were filtered
off, washed with a small amount of methanol and dried in air. Crys-
tals suitable for X-ray diffraction analysis were obtained upon
recrystallization from methanol.
A 1:1 equimolar methanolic solution of 4-aminoantipyrine
(0.406 g, 0.002 mol) and 2-hydroxybenzaldehyde (0.244 g, 0.002
mol) or 5-bromo-2-hydroxybenzaldehyde (0.402 g, 0.002 mol)
was mixed and slightly heated (80 °C) for 2 h with stirring. The
characteristic yellow precipitate obtained by the Schiff condensa-
tion was filtered off and recrystallized from methanol, yields are
around 85% for both Schiff bases. The Schiff base intermediate
(0.002 mol) was dissolved in 20 mL of ethanol, then sodium boro-
hydride (NaBH4, 0.003 mol) was added in portions under vigorous
stirring until the disappearance of the yellow color. Then reaction
mixture was diluted with 100 mL of water and the basic solution
was neutralized with HCl until it was neutral (pH 7). Colorless
microcrystals of H2L started to form immediately after the acidifi-
[Co(HL2)2]ÁH2OÁ3CH3OH (3): yield, 88% (based on Co). Anal. Calc.
for C39H48Br2CoN6O8 (M = 947.57): C, 49.43; H, 5.11; N, 8.87.
Found: C, 49.18; H, 5.04; N, 8.75%. IR, cmÀ1: 3196
m(NH), 1650
m
(C=O). ESI-MS: m/z: 833.12 [M–H2O–3CH3OH+H]+.
Table 1
Crystal data and structure refinement details for 3–5.
3
4
5
Formula unit
Formula weight (g molÀ1
Crystal system
Space group
a (Å)
C
39H48Br2CoN6O8
C37H48N6NiO9
779.52
monoclinic
P 21/c
13.383(2)
10.6236(17)
13.363(2)
90
C37H46Br2N6NiO9
937.33
monoclinic
C 2/c
29.2416(10)
10.6365(4)
13.6850(5)
90
)
947.58
monoclinic
P2(1)/n
10.2212(9)
23.9559(18)
17.2575(13)
90
b (Å)
c (Å)
a
(°)
b (°)
98.703(2)
90
105.768(3)
90
105.3570(10)
90
c
(°)
Z
4
2
4
V (Å3)
4177.0(6)
1.507
2.381
1828.4(5)
1.416
0.595
4104.4(3)
1.517
2.479
Dcalc (g cmÀ3
l
)
(Mo K
a
) (mmÀ1
)
Reflections collected
Independent reflections
Rint
47972
10377
0.0467
0.0319, 0.0680
1.002
14561
3930
0.0290
0.0519, 0.1348
1.004
23211
5073
0.0214
0.0418, 0.1166
1.000
Final R1a, wR2b (I P 2
GOF on F2
r)
P
P
a
R1 = ||Fo| À |Fc||/ |Fo|.
P
P
b
2
wR2 = [ [w(Fo À Fc2)2]/ [w(Fo2)2]]1/2
.

74
P.A. Fatullayeva et al. / Polyhedron 44 (2012) 72–76
[Ni(HL1)2]Á4H2OÁCH3OH (4): yield, 82% (based on Ni). Anal. Calc.
and salicylaldehyde or its 5-bromo-derivative with subsequent
reduction with NaBH4 in ethanol. Dissolution of the ligands 1
and 2 followed by deprotonation and introduction of nickel(II) or
cobalt(II) sulfates allowed complexes 3–5 to be isolated upon slow
solvent evaporation as their crystalline solvates (Scheme 2).
Compounds 1 and 2 are colourless, while complexes [Co(HL2)2]Á
H2OÁ3CH3OH (3), [Ni(HL1)2]Á4H2OÁCH3OH (4) and [Ni(HL2)2]Á4H2OÁ
CH3OH (5) are light brown, dark brown and light blue, respec-
tively. In compounds 1 and 2, the broad IR signals centred at
3360, 3480 and 3341, 3184 cmÀ1 can be ascribed to the OH and
NH functional groups, respectively, while sharp and intense peaks
for C37H48N6NiO9 (M = 779.28): C, 57.01; H, 6.21; N, 10.78. Found:
C, 56.76; H, 6.03; N, 10.33%. IR, cmÀ1: 3362
m(NH), 1652 m(C=O).
ESI-MS: m/z: 675.19 [M–4H2O–CH3OH+H]+.
[Ni(HL2)2]Á4H2OÁCH3OH (5): yield, 85% (based on Ni). Anal. Calc.
for C37H46Br2N6NiO9 (M = 937.29): C, 47.41; H, 4.95; N, 8.97.
Found: C, 47.12; H, 4.63; N, 8.72%. IR, cmÀ1: 3213
m(NH), 1648
m
(C=O). ESI-MS: m/z: 832.21 [M–4H2O–CH3OH+H]+.
2.4. X-ray structure determinations
at 1630 and 1638 cmÀ1 can be attributed to
modes. Upon reduction, the characteristic IR signal for the azome-
thine group
(C=N) at 1653 cmÀ1 [17] disappears; the disappear-
m(C=O) stretching
X-ray quality single crystals of complexes 3–5 were immersed
in cryo-oil, mounted in a Nylon loop and measured at a tempera-
ture of 100(2) (3 and 4) or 296(2) K (5) (Table 1). The diffraction
experiments were carried out on a Bruker APEX-II CCD diffractom-
eter. The program SHELXTL [24] was used for collecting frames of
data, indexing reflections and for the determination of the lattice
parameters, SAINTP [24] for integration of the intensity of reflections
and scaling, SADABS [25] for absorption correction, and SHELXTL [26]
for space group and structure determination, least-squares refine-
ments on F2. Positional and thermal parameters of the non-hydro-
gen atoms were refined in the least-squares cycles. All hydrogens
were inserted in calculated positions. Least square refinements
with anisotropic thermal motion parameters for all the non-hydro-
gen atoms and isotropic for the remaining atoms were employed.
m
ance of the characteristic CH=N peaks at d 9.60–9.75 in the 1H
NMR spectra also confirms the reduction. The 1H NMR peaks at d
13.11 (for 1) and 12.94 (for 2) are attributable to the intramolecu-
larly H-bonded phenolic OH group of the salicylaldehyde moiety.
Moreover, ÀCH2À and NÀH protons are observed at d 4.23 and
11.08 (for 1) and 4.32 and 11.42 (for 2).
In the IR spectra of the complexes, the frequencies of the m(C=O)
bond (1650, 1652 and 1648 cmÀ1 for 3, 4 and 5 respectively) are
moved towards higher wavenumbers by approx. 14–20 cmÀ1 in
comparison to the spectra of ligands (1630 and 1638 cmÀ1 for 1
and 2, respectively), confirming coordination through the oxygen
atom. The data of elemental analysis and ESI-mass spectroscopy
are also in accordance with the proposed formulation.
3. Results and discussion
3.1. Synthesis and characterization of compounds 1–5
3.2. Description of the X-ray crystal structures of compounds 3–5
2-Hydroxy-benzyl derivatives of 4-aminoantipyrine, 1 and 2,
were prepared by the Schiff condensation of 4-aminoantipyrine
Crystals of [Co(HL2)2]ÁH2OÁ3CH3OH (3), [Ni(HL1)2]Á4H2OÁCH3OH
(4) and [Ni(HL2)2]Á4H2OÁCH3OH (5) suitable for X-ray diffraction
X
NH2
H3C
N
CH
H3C
O
C
C
C
X
N
N
O
O
HO
H3C
H3C
H
N
N
C2H5OH
+
HO
NaBH4
C2H5OH
H3C
X
CH3
C
H2
NH CH2
N
N
H3C
Br
C
H
C
O
N
i) 2NaOH
C
C
N
O
HO
X = H (1), Br (2)
H3C
ii) CoSO4⋅7H2O
⋅H2O⋅3CH3OH
N
O
Co
O
O
C
C
N
N
N
H
C
C
Br
i) 2NaOH
ii) NiSO4⋅7H2O
H2
i) 2NaOH
ii) NiSO4⋅7H2O
H3C
CH3
3
H3C
H3C
CH3
CH3
C
C
H2
C
H2
N
N
N
N
Br
C
H
N
H
C
O
C
O
N
C
C
O
O
O
Ni
Ni
⋅4H2O⋅CH3OH
⋅4H2O⋅CH3OH
O
O
O
C
C
N
N
N
N
N
H
N
H
C
C
C
C
Br
H2
H2
C
C
H3C
H3C
CH3
CH3
4
5
Scheme 2. Synthesis of derivatives of 4-aminoantipyrine and their complexes.

P.A. Fatullayeva et al. / Polyhedron 44 (2012) 72–76
75
Fig. 1. Ellipsoid plots with the atom labelling scheme (ellipsoids are drawn at the 50% probability level) for complexes 3–5. H atoms and crystallization solvent molecules in
3–5 are omitted for clarity.
Table 2
Selected distances (Å) and angles (°) of 3–5.
3i
4ii
5iii
Co(1)–O(1)
2.2032(14)
Ni(1)–O(1)
2.030(2)
Ni(1)–O(1)
2.0560(15)
Co(1)–N(1)
Co(1)–O(2)
2.1774(16)
2.0206(14)
180.000(1)
89.10(6)
90.90(6)
180.000(1)
94.48(6)
82.32(6)
85.52(6)
97.68(6)
180.00(5)
Ni(1)–N(1)
Ni(1)–O(2)
2.120(2)
2.1701(18)
180.00(8)
91.69(8)
88.31(8)
180.00(10)
90.05(7)
83.63(7)
89.95(7)
96.37(7)
180.0
Ni(1)–N(1)
Ni(1)–O(2)
2.1159(16)
2.1434(14)
180.00(7)
88.32(6)
91.68(6)
180.000(1)
90.59(6)
84.40(6)
89.41(6)
95.60(6)
180.000(1)
O(2)–Co(1)–O(2)#1
O(2)–Co(1)–N(1)#1
O(2)–Co(1)–N(1)
N(1)–Co(1)–N(1)#1
O(2)–Co(1)–O(1)
N(1)–Co(1)–O(1)
O(2)–Co(1)–O(1)#1
N(1)–Co(1)–O(1)#1
O(1)–Co(1)–O(1)#1
O(1)–Ni(1)–O(1)#1
O(1)–Ni(1)–N(1)
O(1)–Ni(1)–N(1)#1
N(1)–Ni(1)–N(1)#1
O(1)–Ni(1)–O(2)
N(1)–Ni(1)–O(2)
O(1)–Ni(1)–O(2)#1
N(1)–Ni(1)–O(2)#1
O(2)–Ni(1)–O(2)#1
O(1)–Ni(1)–O(1)#1
O(1)–Ni(1)–N(1)#1
O(1)–Ni(1)–N(1)
N(1)–Ni(1)–N(1)#1
O(1)–Ni(1)–O(2)
N(1)–Ni(1)–O(2)
O(1)–Ni(1)–O(2)#1
N(1)–Ni(1)–O(2)#1
O(2)–Ni(1)–O(2)#1
i
ii
iii
Symmetry transformations used to generate equivalent atoms: #1 Àx,Ày + 1,Àz + 2; #1 Àx,Ày + 1,Àz; #1 Àx + 3/2,Ày + 1/2,Àz + 1.
analysis were obtained upon recrystallization from methanol solu-
tion; schematic representations of 3–5 are shown in Scheme 2,
while the ellipsoid plots are depicted in Fig. 1. In all the complexes,
the positive charges of the metal ions are neutralized by the depro-
tonated phenoxy oxygens of H2L1,2. The metal atoms exhibit simi-
lar distorted octahedral environments, with two coordinated
oxygen and one nitrogen atom from each of the H2L1,2 ligands,
the axial positions being occupied by the oxygen atoms (Fig. 1).
In compound 3, the O(1), N(1) and Co(1) atoms form the basal
plane with the Co(1)–O(1) and Co(1)–N(1) distances being
2.2032(14) and 2.1774(16) Å, respectively (Table 2). The apical
positions are occupied by two O(2) atoms with a Co(1)–O(2)
distance of 2.0206(14) Å. The cobalt atom belongs to a fused
five-membered Co1–N1–C1–C2–O1 and six-membered Co1ÀN1–
C18–C13–C12–O2 metallacycle. A regular geometric configuration
was found with O(2)–Co(1)–N(1)#1, O(2)–Co(1)–N(1), O(2)–
Co(1)–O(1), N(1)–Co(1)–O(1), O(2)–Co(1)–O(1)#1 and N(1)–
Co(1)–O(1)#1 angles of 89.10(6), 90.90(6), 94.48(6), 82.32(6),
85.52(6) and 97.68(6)°, respectively.
Complexes 4 and 5 consist of neutral [Ni(HL1)2] and [Ni(HL2)2]
units, co-crystallized with four water and one methanol molecule.
The nickel atoms in both complexes 4 and 5 also have a distorted
octahedral geometry with two oxygen and one nitrogen atom of
each ligand being coordinated. In both complexes, two N(1) and
two O(2) and the Ni(1) atom form the basal plane, with Ni(1)–
N(1) 2.120(2) and Ni(1)–O(2) 2.1701(18), and Ni(1)–N(1)
2.1159(16) and Ni(1)–O(2) 2.1434(14) Å for 4 and 5, respectively.
The apical positions are occupied by O(1) with a Ni(1)–O(1) dis-
tance of 2.030(2) and 2.0560(15) Å in 4 and 5, respectively.
The bonding parameters in 3–5 are comparable to those of
other metal complexes with SBA ligands [18]. Furthermore, owing
to the presence of solvent (methanol and water) molecules, the
overall crystal structure is stabilized by multiple OÀHÁ Á ÁO hydro-
gen bonds, which give rise to 1D chains (for example, see Fig. 2
for 4). The non-coordinated water and methanol molecules form
hydrogen bonds with coordinated carbonyl and phenoxy oxygens,
and with the imino nitrogen atom. The average H2OÁ Á ÁO, H2OÁ Á ÁN,
CH3HOÁ Á ÁO and CH3HOÁ Á ÁN distances of the hydrogen bonds in 3–5

76
P.A. Fatullayeva et al. / Polyhedron 44 (2012) 72–76
complexes 3–5 are related, leading to 1D hydrogen-bonding 1D
networks involving O(w)–H and imine N, phenoxy and carbonyl
O atoms.
Appendix A. Supplementary data
CCDC 872243–872245 contain the supplementary crystallo-
graphic data for 3–5, respectively. These data can be obtained free
of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
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4. Conclusions
Three new CoII and NiII complexes with 2-hydroxy-benzyl
derivatives of 4-aminoantipyrine (synthesized by the Schiff
condensation of salicylaldehyde and 4-aminoantipyrine with sub-
sequent reduction) as ligands have been prepared and character-
ized by convenient methods, while their structures in the solid
state have been determined by X-ray crystallography. The metal
centres in the complexes have a distorted octahedral geometry,
with the equatorial positions occupied by amino nitrogens and
carbonyl oxygens of the 4-aminoantipyrine moieties, while the
phenoxy oxygen atoms are seated at the apical positions. The num-
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