Synthesis and spectrothermal studies of vitamin B13 complexes of cobalt(II) and nickel(II) with 4-methylimidazole: Crystal structure of [Ni(HOr)(H2O)(4-Meim)3]2 · 5H2O

Article abstract of DOI:10.1016/j.poly.2006.05.010

The aquatris(4-methylimidazole)orotatocobalt(II), [Co(HOr)(H₂O)(4-Meim)₃] (1) and bis[aquatris(4-methylimidazole)orotatonickel(II)] pentahydrate, [Ni(HOr)(H₂O)(4-Meim)₃]₂ · 5H₂O (2) have be

Full text of DOI:10.1016/j.poly.2006.05.010

Polyhedron 25 (2006) 2985–2992
www.elsevier.com/locate/poly
Synthesis and spectrothermal studies of vitamin B13 complexes
of cobalt(II) and nickel(II) with 4-methylimidazole: Crystal structure
of [Ni(HOr)(H O)(4-Meim) ] Æ 5H O
2
3 2
¨
2
a,
b
c
d
*
Okan Zafer Yeßsilel , Mustafa Serkan Soylu , Halis Olmez , Orhan B u¨ y u¨ kg u¨ ng o¨ r
a
Department of Chemistry, Faculty of Arts and Sciences, Eskißsehir Osmangazi University, 26480 Eskißsehir, Turkey
Department of Physics, Giresun Faculty of Arts and Sciences, Karadeniz Technical University, Giresun, Turkey
b
c
Department of Chemistry, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139 Kurupelit, Samsun, Turkey
Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139 Kurupelit, Samsun, Turkey
d
Received 7 April 2006; accepted 2 May 2006
Available online 19 May 2006
Abstract
The aquatris(4-methylimidazole)orotatocobalt(II), [Co(HOr)(H O)(4-Meim) ] (1) and bis[aquatris(4-methylimidazole)orotato-
2
3
nickel(II)] pentahydrate, [Ni(HOr)(H O)(4-Meim) ] Æ 5H O (2) have been synthesized and characterized by means of elemental analysis,
2
3 2
2
thermal analysis, IR, UV–Vis and mass spectroscopic studies. The crystal structure of 2 was also determined by single crystal X-ray dif-
fraction. The Ni(II) complex contains the isomers K and D of [Ni(HOr)(H O)(4-Meim) ], self-assembled through complementary p–p
2
3
and CAHꢀ ꢀ ꢀp interactions, leading to an intricate two-dimensional array. The Co(II) and Ni(II) ions in [M(C H N O )(H O)(C H N ) ]
5
2
2
4
2
4
6
2 3
are chelated to the deprotonated N3 pyrimidine atom and to the carboxylate oxygen atom of the bidentate orotate dianion, and to the
three nitrogen atoms of the 4-Meim ligands, and their octahedral geometries are completed by an aqua ligand. The thermal decompo-
sition pathway of the complexes has been predicted by the help of thermal analysis (TG, DTG and DTA) and mass spectroscopic data.
ꢀ
2006 Elsevier Ltd. All rights reserved.
Keywords: Orotate complexes; 4-Methylimidazole; Thermal decomposition
1
. Introduction
sponding anionic species for metal ions, which is held
responsible for the obviously successful application of
metal orotates in curing syndromes associated with a defi-
ciency of a variety of metals such as calcium, magnesium,
zinc or iron [5,6]. The orotato anion may exhibit versatile
coordinating modes such as monodentate [7–12], bidentate
[13–30], bridging ligand [30–35] and counter anion [36–39].
In this study, we describe the preparation, spectroscopic
characterization (IR and UV–Vis) of orotate complexes
of Co(II) (1) and Ni(II) (2) with 4-methylimidazole
(Scheme 1(b)). The 4-methylimidazole coordinated to the
metal ions appears to be 5-methylimidazole due to the ste-
ric effect of methyl groups. The first thermal decomposition
pathway of the complexes has been predicted with the help
of thermal analysis (TG, DTG and DTA) and mass spec-
troscopic data. The crystal structure of 2 has also been
determined by single crystal X-ray diffraction.
Vitamin B13 (Orotic acid, H Or, Scheme 1(a)) and its
3
derivatives are of great importance in biological systems,
due to their significance in biosynthesis of pyrimidine
nucleotides of DNA [1–3]. In recent years, research in bio-
inorganics has revealed the important role of metal ions in
most biological processes. For these reasons, metal oro-
tates have recently attracted growing attention in medicine.
Furthermore, nickel, magnesium, palladium and platinum
orotate complexes have been screened as therapeutic agents
for cancer [4]. Recent interest has focused on the proposed
biological carrier function of orotic acid and the corre-
*
Corresponding author. Tel.: +90 02222393750.
E-mail address: yesilel@ogu.edu.tr (O.Z. Yeßsilel).
0
277-5387/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2006.05.010

2986
O.Z. Yeßsilel et al. / Polyhedron 25 (2006) 2985–2992
O
C OH
(4)
H C
H C
H
(1)
(
3)
H
3
3
(
4)
(5)
N(3)
N
(5)
N
(6)
(2)
(
5)
(4)
(
2)
(2)
O
N
(1)
O
(1)N
H
(3)
N
H
(a)
(b)
Scheme 1. Structures of the ligands: (a) vitamin B13; (b) 4(5)-methylimidazole tautomers.
2
. Experimental
range 1.87–28.08ꢁ at 100 K. Data collections: Stoe X-
AREA [40]. Cell refinement: Stoe X-AREA [40]. Data
reduction: Stoe X-RED [40]. The structure was solved by
direct-methods using SIR97 [41] and anisotropic displace-
ment parameters were applied to non-hydrogen atoms in
2
.1. Preparation of the complexes
A solution of 4-Meim (0.82 g, 10 mmol) in methanol
2
(
10 ml) was added dropwise with stirring to a solution
a full-matrix least-squares refinement based on F using
of [Co(HOr)(H O) ] Æ H O [24] (0.76 g, 2.5 mmol) or
SHELXL-97 [42]. Molecular drawings were obtained using
ORTEP-III [43] and DIAMOND [44]. All H atoms except
for water hydrogens were treated as riding. Restrain was
applied to water hydrogens to idealized geometry.
2
4
2
[
Ni(HOr)(H O) ] Æ H O [20] (0.76 g, 2.5 mmol) in distilled
2 4 2
water (30 ml). The solution was heated to 60 ꢁC in a tem-
perature-controlled bath and then stirred for 5 h at 60 ꢁC.
The reaction mixture was then cooled to room tempera-
ture. The red and blue crystals formed for the Co(II) and
Ni(II) complexes, respectively, were filtered and washed
with 10 ml of cold distilled water and methanol, and dried
in air. Anal. Calc. for C H N O Co: C, 42.78; H, 4.65; N,
3. Results and discussion
3.1. UV–Vis spectra and magnetic susceptibility
1
7
22
8
5
2
3.47. Found: C, 43.02; H, 4.52; N, 23.24%. Anal. Calc. for
The kmax values of the two absorption bands in the UV–
C H N O Ni : C, 39.11; H, 5.21; N, 21.46. Found: C,
ꢁ1
ꢁ1
3
4
54 16 15
2
Vis spectra of 1 are 384 (e = 22 L mol cm ) and 522 nm
3
9.12; H, 5.28; N, 21.74%.
ꢁ1
ꢁ1
(
e = 34 L mol cm ). These values were assigned to the
4
4
following d–d transitions, m : T1g ! T (P) and m :
3
1g
2
2
.2. Materials and measurements
4
4
4
4
T1g ! A , respectively. m : T ! T transition was
2g
1
1g
2g
not observed which is of low energy and shifts to the IR
All chemicals used were analytical reagent products. The
region and the D values for 1 could not be calculated.
0
elemental and mass spectroscopic analysis was carried out
The electronic spectrum of 2 in H O exhibits two absorp-
2
¨
_
in TUBITAK Marmara Research Centre of Turkey. Mass
spectroscopic analysis was performed on a Fisons MD 800
mass spectrometer coupled to a Fisons 8000 GC and FAB
ionisation source. Magnetic susceptibility measurements at
room temperature were performed using a Sherwood Sci-
entific MXI model Gouy magnetic balance. The UV–Vis
spectra were obtained for an aqueous solution of the com-
tion bands at 540 and 884 nm and the corresponding e val-
ꢁ1
ꢁ1
ues are 21 and 18 L mol cm , respectively. These values
3
3
3
3
were assigned to m : A ! T and m : A ! T d–d
2
2g
1g
1
2g
2g
transitions. The D value for 2 was calculated as
0
ꢁ1
8
1
1300 cm since D = m for d complexes [45].
0 1
The complexes 1 and 2 exhibit magnetic moment values
of 4.27 and 2.41 BM which corresponds to three and two
unpaired electrons, respectively, which are consistent with
ꢁ
3
plexes (10 M) with a Unicam UV2 spectrometer in the
range 900–190 nm. The IR spectra were recorded in the
ꢁ
1
4
000–400 cm region with a Mattson 1000 FT-IR spec-
Table 1
a
ꢁ1
)
trometer using KBr pellets. A TG8110 thermal analyzer
was used to record simultaneous TG, DTG and DTA
curves in static air atmosphere at a heating rate of
IR spectra of the complexes (cm
Complexes
1
2
mOH
mN(3)H; mNH
3544 s
3255 m*
3498 m
3222 m*
ꢁ1
1
0 K min
in the temperature range 20–1000 ꢁC using
ꢂ
Meim
platinum crucibles. Highly sintered a-Al O was used as a
reference and the DTG sensitivity was 0.05 mg s
mN(1)
mCH
H
3207 m
3087–2971 w
1639 s
1620 s
1483 m
1427 w; 1373 m*
522 w; 466 w
3176 m
3012–2873 w
1614 vs, b
2
3
ꢁ
1
.
mC@Oacid + mC(2)@O
mC(6)@O + mC@C
mC@NHOr; mC@N
2
.3. Crystallographic analysis
ꢂ
1487 m
1398 m; 1371 m*
576 w; 444 w
Meim
ꢂ
dN(1)H; dNH
M–O; M–N
a
Meim
Data collection was performed on a STOE IPDS II
image plate detector using Mo Ka radiation
Abbreviations: w – weak; m – medium; s – strong; vs – very strong,
˚
(
k = 0.71073 A). Intensity data were collected in the h
b – broad.

O.Z. Yeßsilel et al. / Polyhedron 25 (2006) 2985–2992
2987
a weak field octahedral geometry as expected. However,
this magnetic moment value is lower than the spin only
value for two unpaired electrons in the Ni(II) complex,
indicative of some antiferromagnetic behavior [46].
3.2. IR spectra
The most significant frequencies in the IR spectra of
both complexes are given in Table 1. The strong bands at
ꢁ1
3
544 and 3498 cm are attributed to the m(OH) vibration
of water molecules in the IR spectra of 1 and 2. The bands
ꢁ1
at 3255–3176 cm are attributed to the NH stretching
vibration in HOr and 4-Meim ligands. This data substanti-
ates the suggestion that 4-Meim molecules coordinate to
the central metal ion in their neutral form. The distinct
weak bands in the 3012–2873 cm region can be assigned
to the CH stretching vibrations of the HOr and 4-Meim
ligands in the complexes. The carbonyl groups appear as
Fig. 1. TG, DTG and DTA curves of 1.
ꢁ
1
ꢁ
1
two main peaks at 1700 cm
[mC@O(acid) + mC(2)@O] and
ꢁ1
1660 cm
[mC(6)@O + mC@C] in the free H Or [7]. These
bands appear as strong bands at 1639 and 1620 cm in
the spectrum of the Co(II) complex, while the Ni(II) com-
3
ꢁ1
ꢁ1
plex give a single and broad absorption band at 1614 cm
,
probably due to overlapping of the two bands. The weak
ꢁ1
bands in the 450–500 and 500–600 cm region are due
to M–N and M–O stretching vibrations, respectively. In
the Co(II) and Ni(II) complexes, the orotate ligand is coor-
dinated as dianionic and bidentate through the carboxylic
O and N(3) of the pyrimidine ring, while the 4-methylimi-
dazole ligand is coordinated as neutral and monodentate
through the N atom.
Fig. 2. TG, DTG and DTA curves of 2.
Fig. 3. The mass spectrum of 1.

2988
O.Z. Yeßsilel et al. / Polyhedron 25 (2006) 2985–2992
H
+
H
N
N
OH2
Co
H3C
H
N
N
CH3
O
N
N
O
N
C
O
H3C
N
H
O
m/z = 478
H O
H- O
2
-2(4-Meim)
-
2
-
(4-Meim)
H
+
H
+
H
+
H
H
N
N
N
N
N
OH2
Co
H3C
H
H3C
H3C
N
N
CH3
N
N
CH3
N
Co
N
Co
N
O
O
O
C
N
N
O
C
O
O
C
O
N
O
O
H3C
N
N
N
H
H
H
O
O
O
m/z = 459
m/z = 378
m/z = 314
CO
-
-
CO2
H
+
H
N
H
+
OH2
Co
H3C
N
N
N
H3C
N
N
CH3
O
Co
N
H
O
N
N
N
O
N
H3C
N
H
O
H
O
m/z = 286
m/z = 416
-
CO
-
CH3
H
+
N
OH2
Co
H3C
H
N
H
+
N
N
H3C
H
N
N
N
O
N
Co
N
N
N
O
H
H3C
O
N
m/z = 258
CO
H
O
-
m/z = 400
H
+
N
OH2
Co
+
H3C
H
N
H3C
N
O
N
N
N
m/z = 83
H
m/z = 227
Fig. 4. Mass spectral fragmentation pattern of 1.

O.Z. Yeßsilel et al. / Polyhedron 25 (2006) 2985–2992
2989
3
3
.3. Thermal analysis
49–173 ꢁC range temperature, giving an endothermic effect.
Initially 5 mol of crystal water are removed in the 49–
138 ꢁC range temperature (DTGmax = 128 ꢁC, found:
8.51, Calc. 8.63%) and then two moles coordinated water
molecules are released in the 139–173 ꢁC range temperature
(DTGmax = 147 and 163 ꢁC, found: 3.33, Calc. 3.45%). The
blue octahedral complex loses water molecules upon heat-
ing yielding a violet, probably square pyramidal dehy-
drated species. The second stage is related to the release
of 4-Meim ligands and partial decomposition of the orotate
.3.1. [Co(HOr)(H O)(4-Meim) ] (1)
2
3
Thermal decomposition of 1 proceeds in three stages
Fig. 1). The first stage, in the 122–190 ꢁC temperature
range, corresponds to the loss of one aqua ligand (found:
.78; Calc. 4.35%), giving an endothermic effect
DTGmax = 161 ꢁC). The originally red colour of the com-
(
3
(
plex changes to blue-green on dehydration. The anhydrous
complex reverts immediately to [Co(HOr)(H O)(4-Meim) ]
2
3
after cooling in the open atmosphere. The endothermic sec-
ond stage of the Co(II) complex, observed as several con-
secutive steps, is related to the decomposition of the
neutral 4-Meim ligans and decarboxylation of the orotato
ligand proceeds with release of CO /CO. In the following
2
stage, the strong exothermic mass loss process occurs in a
single step. During this stage, the remaining organic part
is abruptly burnt (DTGmax = 431 ꢁC). The final decompo-
sition product, NiO, was identified by IR spectroscopy
(found: 82.64, Calc. 85.70%).
ligand, in the 191–380 ꢁC temperature range (DTGmax
=
2
41, 255, 276 and 300 ꢁC). The mass spectrum of 1 also
supports the decomposition of the orotate ligand with
release of CO /CO (Fig. 3). In the last stage the strong exo-
3.4. Analysis of the mass spectrum
2
thermic peak of the DTA curve (DTGmax = 431 ꢁC) is
associated with the burning of the organic residue, leading
finally to Co O . The endothermic peak at 889 ꢁC
The volatile products observed in the thermal decompo-
sition process were also observed in the mass spectrometer
ionization process, except molecular peak, and it was con-
cluded that the ionization and thermal decomposition
pathway of the complex resemble each other.
3
4
(
DTGmax) is related to the conversion of Co O to CoO.
3 4
The overall weight loss 82.19% (Calc. 84.30%) agrees with
the propose structure well.
The mass spectrum of 1 was recorded to establish a rela-
tion between the thermal and ionization process to predict a
more appropriate thermal decomposition pathway. The
mass spectrum recorded by the FAB technique is given in
3
.3.2. [Ni(HOr)(H O)(4-Meim) ] Æ 5H O (2)
2 3 2 2
The thermal decomposition of 2 (Fig. 2) is similar to 1.
In the first stage, dehydration of the complex occurs in the
Fig. 5. ORTEP III view of 2 with the atom numbering scheme (30% probability ellipsoids).

2990
O.Z. Yeßsilel et al. / Polyhedron 25 (2006) 2985–2992
Fig. 3. The mass spectrum of 1 is not very complicated and
only the major peaks, which were produced in significant
quantities, were apparent. In addition to this, the molecule
+
ion peak (M ) (m/z = 478) of 1 was visible in the mass spec-
trum. The peak observed at m/z = 459 possibly corresponds
to the [Co(HOr)(4-Meim) ] molecule produced by the loss
3
of a water molecule from [Co(HOr)(H O)(4-Meim) ] in
2
3
the ionization process. The compound formed from
Co(HOr)(4-Meim) ] by the release of CO was observed
[
3
2
in the mass spectrum at m/z = 416. In the literature, orotate
and derivative complexes with similar structures are also
reported to be decomposed by release of CO [47–49]. The
2
compound, [Co(uracil)(im)(4-Meim) ], formed by the loss
2
of the CH ion was observed in the mass spectrum at
3
m/z = 400. This type of ionization of the 4-Meim ligand in
the [Zn(Han) (4-Meim) ] (Han = o-aminobenzoate) com-
2
2
plex has been reported earlier [50]. The peaks observed at
m/z = 378 and m/z = 314 values may correspond to
[
Co(HOr)(4-Meim) ] and [Co(HOr)(H O)(4-Meim)] com-
2 2
plexes, respectively. Formation of these fragments in the
thermal process may also be proved by the thermal analysis
data. The possible decomposition products of the
[
Co(HOr)(H O)(4-Meim) ] complex shows in the ionization
2 3
process (Fig. 4).
3
(
.5. Crystal structure of [Ni(HOr)(H O)-
2
4-Meim) ] Æ 5H O
3
2
2
Fig. 6. Octahedral representation of 2. Distorted octahedra are shaded
dark. All H atoms and free water molecules have been omitted for clarity.
The asymmetric unit of 2 is composed of two crystallo-
graphic independent [Ni(HOr)(H O)(4-Meim) ] molecules
2
3 2
and five lattice water molecules, as shown in Fig. 5. The
Ni(II) ion in [Ni(HOr)(H O)(4-Meim) ] is in a distorted
and the ring [N(1)AC(1)AC(5)AO(1) = 1.2(3)ꢁ and
N(9)AC(19)AC(18)AO(5) = ꢁ7.5(3)ꢁ]. This torsion angle
indicates distortion of the orotate ligand caused by coordi-
nation to the Ni(II) ion. While this torsion angle of molecule
B is wider than the reported values in uncoordinated orotic
acid ligands 5.9(4)ꢁ [37] and 5.0(2)ꢁ [38], the value for mole-
cule A is even less. Of all the NAC bonds in the uracil ring of
the orotate ligand, N(1)AC(1), N(1)AC(4), N(9)AC(19) and
N(9)AC(12) are the shortest, with values in the range
2
3 2
octahedral configuration coordinated by a bidentate HOr
ligand, a coordinated water molecule and three 4-Meim
ligands (Fig. 6). The absolute configuration of the Ni(II) cen-
ter is K and D, which is the highest energy conformation [51].
The distorted octahedral coordination geometry is com-
prised of a N atom and a carboxylate O atom from a doubly
deprotonated bidentate orotateligand, one aquaO atom and
three N atoms from imidazole molecules. The N and O
atoms of orotate are bonded to the metal to form a five-mem-
bered chelate ring [Ni(1)AN(1) = 2.0835(18) and Ni(1)A
˚
1.340(2)–1.358(2) A. This indicates a considerable p-elec-
tron delocalization within the C(2)AC(1)AN(1)AC(4) and
C(20)AC(19)AN(9)AC(22) skeletons. The C@O bond
lengths for exocyclic atoms are in the range 1.251(2)–
˚
O(1) = 2.0783(15) A in molecule A and Ni(2)AN(9) =
˚
˚
2
.1184(18) and Ni(2)AO(5) = 2.0605(16) A in molecule B].
1.260(2) A. These values are slightly longer than those in
All the NANiAN, NANiAO and OANiAO bond angles
deviate significantly from 90ꢁ or 180ꢁ, which is presumably
the result of the steric constraints arising from the shape of
the ligands. The angles subtended at the Ni atom by the oro-
tate ligand are 79.66(6)ꢁ in molecule A and 79.92(6)ꢁ in mol-
ecule B, which is in agreement with values previously
reported for other orotate-containing Ni(II) complexes
typical orotate complexes and this can be attributed to the
intermolecular hydrogen bonding (Table 2).
The orotate molecule seems to have a degree of elasticity
with regard to its coordination to metal centers. In com-
plexes of HOr with Ni(II) [37,52], Cu(II) [16] and Zn(II)
[21], the C(4)AN(1)AC(1) and C(22)AN(9)AC(19) angles
are smaller [119.16(16)ꢁ in molecule A and 118.12(16)ꢁ in
molecule B, 118.25(15)ꢁ, 118.9(11)ꢁ, 117.9(2)ꢁ and
118.1(4)ꢁ, respectively] than that found in orotic acid
122.8(3)ꢁ [53], 123.07(14)ꢁ [38] and 122.8(3)ꢁ [37]. This
shrinkage for this angle is due to the metal coordination
at the N atom, which causes widening of the adjacent
NACAC and NACAN angles (Table 2).
[
20,52]. This ‘bite’ angle is far from the ideal value of 90ꢁ
because of the constrained geometry of the orotate ligand.
The orotate ligand in 2 is essentially planar (r.m.s. devia-
˚
tions = 0.0600 and 0.0150 A in molecules A and B, respec-
tively), with a slight deviation from planarity arising from
the non-zero torsion angle between the carboxylate group

O.Z. Yeßsilel et al. / Polyhedron 25 (2006) 2985–2992
2991
Table 2
Crystal data and structure refinement for 2
Empirical formula
Formula weight
Crystal dimensions (mm)
Crystal shape
[C17
1044.35
0.35 · 0.33 · 0.12
plate
22 8 5 2 2
H N NiO ] Æ 5H O
Colour
Unit cell dimensions
blue
˚
a (A)
9.809(4)
16.444(5)
14.763(6)
98.961(3)
2352.2(15)
2
˚
b (A)
˚
c (A)
b (ꢁ)
˚
3
Volume (A )
Z
Crystal system, space group
monoclinic, P2
1.475
0.88
1
ꢁ3
Density qcalc (Mg m
)
ꢁ
1
Absorption coefficient (mm
Data collection
)
STOE IPDS 2 diffractomer
x-scan)
(
Temperature (K)
h Range (ꢁ)
100
1.87–28.08
Index ranges
ꢁ12 6 h 6 12; ꢁ21 6 k 6 21;
ꢁ
19 6 l 6 19
Flack parameter [55]
Reflections collected
Independent reflections
Reflections with I > 2r(I)
Absorption correction
0.001(6)
40583
11158, Rint = 0.065
10592
integration
0.681, 0.890
18, 665
Fig. 7. Crystal packing and H bond interactions. Distorted octahedral are
drawn as shaded dark.
Tmin, Tmax
The carboxylate CAO distances in the orotate anion
also display some variability, depending on their environ-
ment. The CAO distances are practically equal in the unco-
Restraints; parameters
˚
3
Largest difference in peak and hole (e A ) 0.73, ꢁ0.61
Final R indices I > 2r(I)
R indices (all data)
R
R
1
= 0.0275, wR
= 0.0312, wR
2
2
= 0.0634
= 0.0644
2ꢁ
1
ordinated HOr anion and its Ni(II) and Li(I) complexes
2
Goodness-of-fit on |F|
1.03
[
54]. In 2, the CAO bond lengths are in the range 1.244(2)–
Table 3
˚
Geometric parameters (A, ꢁ) for 2
Ni(1)—N(7)
Ni(1)—O(1)
Ni(1)—N(1)
Ni(1)—N(5)
Ni(1)—N(3)
Ni(1)—O(9)
Ni(2)—O(5)
Ni(2)—N(13)
Ni(2)—N(11)
Ni(2)—N(15)
Ni(2)—N(9)
Ni(2)—O(10)
O(1)—C(5)
O(2)—C(5)
O(3)—C(4)
O(4)—C(3)
O(5)—C(18)
O(6)—C(18)
O(7)—C(22)
O(8)—C(21)
N(1)—C(4)
N(1)—C(1)
N(2)—C(3)
N(2)—C(4)
N(3)—C(14)
N(3)—C(16)
2.0602(17)
2.0783(15)
2.0835(18)
2.0939(18)
2.1055(18)
2.1286(16)
2.0605(16)
2.0701(18)
2.0702(19)
2.0748(18)
2.1184(18)
2.1369(16)
1.268(2)
1.244(2)
1.251(2)
1.260(2)
1.250(3)
1.248(3)
1.257(2)
1.258(3)
1.345(3)
N(4)—C(14)
N(4)—C(15)
N(5)—C(6)
N(5)—C(8)
N(6)—C(6)
1.347(3)
1.373(3)
1.312(3)
1.386(3)
1.350(3)
1.371(3)
1.317(3)
1.374(3)
1.347(3)
1.369(3)
1.340(2)
1.358(2)
1.372(3)
1.385(3)
1.307(3)
1.379(3)
1.345(3)
1.362(3)
1.318(3)
1.382(3)
1.347(3)
1.377(3)
1.311(3)
1.368(3)
1.344(3)
1.361(4)
N(6)—C(7)
N(7)—C(12)
N(7)—C(10)
N(8)—C(12)
N(8)—C(11)
N(9)—C(22)
N(9)—C(19)
N(10)—C(21)
N(10)—C(22)
N(11)—C(25)
N(11)—C(23)
N(12)—C(25)
N(12)—C(24)
N(13)—C(27)
N(13)—C(29)
N(14)—C(27)
N(14)—C(28)
N(15)—C(33)
N(15)—C(31)
N(16)—C(33)
N(16)—C(32)
1.353(3)
1.369(3)
1.393(2)
1.313(3)
1.385(3)
C(4)—N(1)—C(1)
C(3)—N(2)—C(4)
C(4)—N(1)—C(1)—C(2)
119.16(16)
124.90(17)
1.5(3)
C(22)—N(9)—C(19)
C(21)—N(10)—C(22)
C(22)—N(9)—C(19)—C(20)
118.12(16)
124.54(17)
0.6(3)

2992
O.Z. Yeßsilel et al. / Polyhedron 25 (2006) 2985–2992
˚
.268(2) A, which is comparable with those in similar
Ni(II) complexes [37,52].
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731.
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1
3
[
The 4-Meim rings in 2 are individually planar, with
B36 (1980) 1187.
˚
r.m.s. deviations in the range of 0.0017–0.0084 A. The
[21] I. Mutikainen, Inorg. Chim. Acta 136 (1987) 155.
dihedral angles between the apical positioned 4-Meim rings
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m228.
are 44.1(8)ꢁ and 39.7(7)ꢁ. The internal geometries are as
expected, with the bond lengths NAC [in the range of
_
¨
[
24] H. I c¸ budak, H. Olmez, O.Z. Yeßsilel, F. Arslan, P. Naumov, G.
Jovanovski, A.R. Ibrahim, A. Usman, H.K. Fun, S. Chant-
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1
1
.307(3)–1.318(3) A] and CAC [in the range of 1.347(3)–
˚
.364 (3) A] corresponding exactly to typical double-bond
lengths.
As a result of the existence of five free crystallization
[25] H. Olmez, H. Icbudak, O.Z. Yesilel, C. Arici, D. Ulku, Z. Kristallogr.
219 (2004) 300.
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Crystallogr. C60 (2004) m563.
waters, the crystal is mainly stabilized by many strong inter-
molecular H bonds O(W)AH. . .O(W), O(W)AH. . .O, O(W)
AH. . .N, NAH. . .O(W), etc. There are also intramolecular
H bonds between coordinated water molecules O9, O10
and exocyclic O atoms of orotate and also imidazole C(8)
and C(27) atoms and coordinated water molecules. From
all of these intermolecular interactions, a three-dimensional
hydrogen-bonded network results (Table 3, Fig. 7).
¨
[
27] O.Z. Yeßsilel, F. Tezcan, H. Olmez, H. Paßsao g˘ lu, O. B u¨ y u¨ kg u¨ ng o¨ r, Z.
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[
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have been deposited at the CCDC as supplementary data,
CCDC No. 603935. Copies of the data can be obtained on
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