Ni(II) coordination compounds based on mixed phthalate and aromatic amine ligands: Synthesis, crystal structures and magnetic properties

Article abstract of DOI:10.1016/j.ica.2004.10.028

Three new coordination compounds, [Ni(Pht)(Py)₂(H ₂O)₃] (1), [Ni(Pht)(β- Pic)₂(H ₂O)₃] ? H₂O (2) and [Ni(Pht)(1-MeIm) ₂(H₂O)₃] (3) (where Pht^2- = dianion of o-phthalic acid; Py = pyridine, β-Pic = 3-methylpyridine, 1-MeIm = 1-methylimidazole), have been synthesized and characterized by IR spectroscopy and thermogravimetric analysis. Crystallographic studies 1-3 reveal that each Ni(II) center has a distorted octahedral geometry being coordinated by two nitrogen atoms of aromatic amines, one oxygen atom from a carboxylate group of a phthalate ligand and three water molecules. Pht^2- anions act as monodentate ligands, while the remaining uncoordinated carboxylate oxygen atoms participate in the formation of hydrogen bonding. The uncoordinated oxygen atoms form hydrogen bonds with the coordinated water molecules from adjacent complexes creating a centrosymmetric dimer unit. Further, these dimer units are connected by O-H?O hydrogen bonds in double-chains. Depending on the nature of aromatic amines, the arrangement of these double-chains differs. The double-chains are held together only by van der Waals interactions in 1. In contrast, in 2 these chains form layers by π-π interactions between antiparallel molecules of β-Pic as well as by π-π interactions between β-Pic and Pht aromatic rings. In complex 3, the double-chains are knitted together via C-H?O hydrogen bonds between the methyl group of 1-MeIm and the coordinated carboxylate oxygen atom of Pht, as well as π-π contacts involving antiparallel 1-MeIm cycles. The thermal dependence of the magnetic susceptibilities for compounds 1 and 2 shows a weak antiferromagnetic interaction between the two Ni²⁺ ions of the hydrogen bonded dimers. For compound 3, a ferromagnetic interaction could be observed. Modeling the experimental data with MAGPACK resulted in: g = 2.22, |D| = 4.11 cm^-1 and J = -0.29 cm^-1 for compound 1, g = 2.215, |D| = 3.85 cm ^-1 and J = -0.1 cm^-1 for compound 2 and g = 2.23, |D| = 4.6 cm^-1 and J = 0.22 cm^-1 for compound 3.

Full text of DOI:10.1016/j.ica.2004.10.028

Inorganica Chimica Acta 358 (2005) 1762–1770
www.elsevier.com/locate/ica
Ni(II) coordination compounds based on mixed phthalate
and aromatic amine ligands: synthesis, crystal structures
and magnetic properties
a,
b
c
c
Svetlana G. Baca *, Irina G. Filippova , Patrik Franz , Christina Ambrus ,
d
e
b
b
Maria Gdaniec , Helen Stoeckli-Evans , Yurii A. Simonov , Olesea A. Gherco ,
a
Tanea Bejan , Nicolae Gerbeleu , Silvio Decurtins
a
c
a
Institute of Chemistry, Academy of Sciences of RM, MD-2028 Chisinau, Republic of Moldova
Institute of Applied Physics, Academy of Sciences of RM, MD-2028 Chisinau, Republic of Moldova
b
c
Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
d
Faculty of Chemistry, A. Mickiewicz University, 60-780 Poznan, Poland
ˆ
e
´ ˆ
Institut de Chimie, Universite de Neuchatel, CH-2007 Neuchatel, Switzerland
Received 10 March 2004; accepted 24 October 2004
Available online 19 November 2004
Abstract
Three new coordination compounds, [Ni(Pht)(Py)2(H2O)3] (1), [Ni(Pht)(b- Pic)2(H2O)3] Æ H2O (2) and [Ni(Pht)(1-MeIm)2(H2O)3]
(3) (where Pht2ꢀ = dianion of o-phthalic acid; Py = pyridine, b-Pic = 3-methylpyridine, 1-MeIm = 1-methylimidazole), have been
synthesized and characterized by IR spectroscopy and thermogravimetric analysis. Crystallographic studies 1–3 reveal that each
Ni(II) center has a distorted octahedral geometry being coordinated by two nitrogen atoms of aromatic amines, one oxygen atom
from a carboxylate group of a phthalate ligand and three water molecules. Pht2ꢀ anions act as monodentate ligands, while the
remaining uncoordinated carboxylate oxygen atoms participate in the formation of hydrogen bonding. The uncoordinated oxygen
atoms form hydrogen bonds with the coordinated water molecules from adjacent complexes creating a centrosymmetric dimer unit.
Further, these dimer units are connected by O–Hꢁ ꢁ ꢁO hydrogen bonds in double-chains. Depending on the nature of aromatic
amines, the arrangement of these double-chains differs. The double-chains are held together only by van der Waals interactions
in 1. In contrast, in 2 these chains form layers by p–p interactions between antiparallel molecules of b-Pic as well as by p–p inter-
actions between b-Pic and Pht aromatic rings. In complex 3, the double-chains are knitted together via C–Hꢁ ꢁ ꢁO hydrogen bonds
between the methyl group of 1-MeIm and the coordinated carboxylate oxygen atom of Pht, as well as p–p contacts involving anti-
parallel 1-MeIm cycles. The thermal dependence of the magnetic susceptibilities for compounds 1 and 2 shows a weak antiferromag-
netic interaction between the two Ni2+ ions of the hydrogen bonded dimers. For compound 3, a ferromagnetic interaction could be
observed. Modeling the experimental data with MAGPACK resulted in: g = 2.22, |D| = 4.11 cmꢀ1 and J = ꢀ0.29 cmꢀ1 for compound
1, g = 2.215, |D| = 3.85 cmꢀ1 and J = ꢀ0.1 cmꢀ1 for compound 2 and g = 2.23, |D| = 4.6 cmꢀ1 and J = 0.22 cmꢀ1 for compound 3.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Nickel(II) compounds; Carboxylates; Phthalate complexes; Crystal structures; Magnetic properties
1. Introduction
o-Phthalate anion is a well-known versatile ligand,
which has been extensively used in the design of coordi-
nation compounds due to a variety of its bonding abili-
*
Corresponding author. Tel.: +373 22 72 5490; fax: +373 22 73
9954/9611.
E-mail address: sbaca_md@yahoo.com (S.G. Baca).
0020-1693/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.10.028

S.G. Baca et al. / Inorganica Chimica Acta 358 (2005) 1762–1770
1763
ties. As a result of the two ortho-carboxylic groups, the
ligand has the capacity to chelate as well as to bridge up
to seven metal centers at once [1, Scheme 1] forming
mono- and polynuclear complexes. Based on analysis
of the crystal structures of phthalates extracted from
the Cambridge Structural Database (CSD) [2] in our
previous report [1], we have shown that the phthalate li-
gand can adopt 26 coordination modes with metal
atoms in the complexes. Moreover, both monodeproto-
nated HPhtꢀ anions and neutral H2Pht molecules are
able to co-exist with fully deprotonated Pht2ꢀ residues
of acid in crystals, leading to some unexpected architec-
tures. In particular, we previously described an extre-
mely unusual dimer [(bpy)2Zn(Pht)H(Pht)Zn(bpy)2]
(HPht)(H2Pht) Æ 2H2O in which [Zn(bpy)2] metal cores
are connected through Phtꢁ ꢁ ꢁHꢁ ꢁ ꢁPht bridge [3]. Addi-
tional strong hydrogen bonds between water molecules
and coordinated and uncoordinated moieties of o-
phthalic acid as well as p–p interactions between unco-
ordinated phthalate moieties and one of bpy molecule
stabilize the structural organization of this complex.
However, the 1,6-bridging mode remains the most
commonly seen in the complexes. In this case, the phth-
alate anion is a bidentate ligand and coordinates to me-
tal ions by one oxygen atom from each of the
carboxylate group. This structural motif of the ligand
promotes the formation of polymeric structures such
as were found in copper(II) [4–9], cobalt(II) [10–12],
zinc(II) [13–15] and other metal complexes [16]. It is
noteworthy that when the 1,6-bridging mode is realized,
the other oxygen atoms from the same carboxylate
groups are also able to coordinate additional metal ions
resulting in supracage assemblies or complicated poly-
meric structures. The good examples of the former are
the fascinating Mn18 [17,18] and Mn10 [19] clusters re-
ported by Christou et al. as well as Winpennyꢀs remark-
able Ni16 [20] and Co13 [21,22] cages, which contain
phthalate ligands displaying rare and unprecedented
bridging modes. For the latter case, we can mention
the coordination polymer [Zn(Pht)(2-MeIm)]n [15]. In
this structure, one of a pair of zinc atoms is linked by
1,6-bridges of two phthalate ligands, while the other is
held together through syn–syn bridging carboxylate
groups in a 1,3-fashion from the same phthalates. As a
result, infinite chains with alternation of 14- and 8-mem-
bered cycles are formed. All these structural and func-
tional versatilities make phthalate ligand an attractive
building unit in the construction of metallopolymers
and clusters. The coordination of residues of Pht2ꢀ or
HPhtꢀ by only one carboxylate group to metal ions is
also of special interest, since the uncoordinated carbox-
ylic group can be important in different catalytic pro-
cesses [23].
imidazole and their derivatives and several interesting
cobalt(II), copper(II) and zinc(II) [1,3,8,12,14,15] com-
plexes have been prepared in our laboratory. However,
despite the characterization of many new complexes of
3d-metals with o-phthalic acid, little work has been done
to synthesize nickel(II) compounds. A search of the
Cambridge Structural Database (CSD version 5.24 [2])
yielded only 11 structural investigations of Ni(II) com-
plexes with the phthalate ligand. It should be noted that
in six of them the moiety of phthalate is monodentate.
Examples of such mononuclear Ni(II) complexes in-
clude [Ni(HPht)2(H2O)4] Æ 2H2O [24] and [Ni(Pht)(ethy-
lenediamine)2(H2O)] [25]. Polleti et al., using chelating
N,N-ligands such as 1,10-phenanthroline, 2,20-bipyri-
dine, and bipyridilamine, synthesized mononuclear
Ni(II) phthalate complexes with common formula
[Ni(Pht)(A)(H2O)3] Æ nH2O (where A = 1,10-phenan-
throline, n = 1 [26]; bipyridylamine, n = 2 [26]; 2,20-
bipyridine, n = 1 [27]), as well as a similar complex
[Ni(Pht)(bpy)(H2O)3] Æ C2H5OH Æ H2O but containing
an additional solvate ethanol molecule [28]. In
{[Ni(Pht)(oxamide oxime)2] Æ 4H2O}n [29] and the
above-mentioned
Ni16
cluster
[Ni16Na6(chp)4
(Pht)10(HPht)2(MeO)10(OH)2(MeOH)20] [20], the Pht
moieties act as bridges and enhance the formation of a
linear polymer in the first case and the supercage struc-
ture in the second one. In the latter case, the bridge is
realized between Ni2+ and Na+ ions. In K2[Ni
(H2O)6](HPht)4 Æ 4H2O
[30],
[Ni(bpy)3]2(HPht)
(NO3)3 Æ 4H2O [31] and [Ni(1-MeIm)6](HPht)2 Æ 2H2O
[1], phthalate does not take part in coordination to
nickel ions and it coordinates to K+ ions in the first
case and plays the role of counter anions in the latter.
Analyzing these data, we can consider the monoden-
tate coordination of the phthalate ligand as the most
favored for the nickel(II) complexes with o-phthalic
acid.
In this paper, we report on the synthesis, character-
ization and crystal structures of three new nickel(II)
phthalate compounds: [Ni(Pht)(Py)2(H2O)3] (1),
[Ni(Pht)(b-Pic)2(H2O)3] Æ H2O
(2)
and
[Ni(Pht)
(1-MeIm)2(H2O)3] (3) (where Pht2ꢀ = dianion of o-
phthalic acid; Py = pyridine, b-Pic = 3-methylpyridine,
1-MeIm = 1-methylimidazole).
2. Experimental
2.1. Materials and physical measurements
All reagents were purchased from commercial sources
and used as received. [Ni(1-MeIm)6](HPht)2 Æ 2H2O was
prepared by the reported procedure [1]. IR spectra were
recorded on a Perkin–Elmer Spectrum One spectrome-
ter in the region 4000–400 cmꢀ1 using KBr pellets. TG
analyses were carried out on a Mettler-Toledo TA 50
We have focused our efforts on synthesis and investi-
gation of 3d coordination compounds based on mixed
phthalate ligand and aromatic amines such as pyridine,

1764
S.G. Baca et al. / Inorganica Chimica Acta 358 (2005) 1762–1770
in dry nitrogen (60 ml minꢀ1) at a heating rate of 5
ꢁC minꢀ1
1481m, 1445m, 1399vs, 1286m, 1248m, 1229m, 1161w,
1112m, 1106m, 1027w, 943m, 828m, 749m, 720m,
683m, 664m, 653m, 617m, 574w.
.
2.2. Synthesis of complexes
2.3. X-ray crystallography
2.2.1. Synthesis of [Ni(Pht)(Py)2(H2O)3] (1)
Experimental data were collected on a KUMA
KM4CCD-j-axis diffractometer with a graphite mono-
chromated Mo Ka radiation at 130 K for 1 and 3.
The crystals were positioned 60 mm from CCD camera.
Six hundred and eighty two frames were measured for 1
and 782 frames for 3 (in six runs). The time of a single
frame measurement was 30 and 4 s over 0.75ꢁ x-scan
for 1 and 3, respectively. The absorption corrections
were introduced by semi-empirical method from symme-
try equivalent reflections [32] for 1, the maximum and
minimum transmission being 0.935 and 0.678, respec-
tively. The data were processed using the KUMA dif-
fraction (Wroclaw, Poland) program. For 2, the
intensity data were collected at 223 K on a Stoe Image
Plate Diffraction System [33] using Mo Ka graphite
monochromated radiation. Image plate distance 70
mm, / oscillation scans 0–200ꢁ, step D/ = 1.0ꢁ. Crystal
data and details of data collections and refinement for
1–3 are given in Table 1. The structures were solved
by direct methods (SHELXS-97 [34]) and refined on F2
To a hot solution of H2Pht (0.83 g, 5 mmol) and
pyridine (3 ml) in water (30 ml) was added a solution
of Ni(O2CCH3) Æ 4H2O (1.24 g, 5 mmol) in water (10
ml). The mixture was heated at reflux for 1 h and left
to stand at r.t. in an open flask. The precipitated blue
crystalline product was collected by filtration, washed
with water, EtOH and Et2O and dried in air. Yield:
1.71 g, 78.62%. Anal. Calc. for C18H20N2NiO7: C,
49.69; H, 4.63; N, 6.44. Found: C, 49.66; H, 4.67; N,
6.41%. IR data (KBr, cmꢀ1): 3209s,br, 1607vs,
1586sh, 1563vs, 1488s, 1449s, 1404vs, 1219m, 1153m,
1084w, 1072s, 1043s, 1015m, 951m, 932m, 887m,
812s, 761s, 698s, 656s, 636s, 592m, 577m. Single crys-
tals suitable for diffraction studies were obtained from
the mother liquid.
2.2.2. Synthesis of [Ni(Pht)(b-Pic)2(H2O)3] Æ H2O (2)
To a hot solution of KHPht (1.02 g, 5 mmol) and
3-methylpyridine (3 ml) in water (25 ml) was added a
solution of Ni(O2CCH3) Æ 4H2O (1.24 g, 5 mmol) in
water (10 ml). The resulting mixture was heated at re-
flux for 1.5 h and the resulting light green precipitate
was collected from the hot solution by filtration. The
filtrate was allowed to stand at r.t. in an open flask.
The blue crystals of 2 suitable for X-ray diffraction
studies were filtered off, washed with water and EtOH
and dried in air. Yield: 0.67 g, 27.86%. Anal. Calc.
for C20H26N2NiO8: C, 49.93; H, 5.45; N, 5.82.
Found: C, 49.62; H, 5.51; N, 5.65%. IR data (KBr,
cmꢀ1): 3395s,br, 3071w,br, 1608sh, 1586sh, 1553vs,
1484m, 1449m, 1405vs, 1240w, 1196w, 1150w,
1130w, 1108w, 1086w, 1056w, 1037w, 820m, 793m,
757m, 702s, 653m, 562w. Single crystals suitable for
diffraction studies were obtained from the mother
liquid.
(
SHELXL-97 [35]) in anisotropic approach for non-
hydrogen atoms. The positions of H-atoms were located
from the difference syntheses of electronic density and
were refined in an isotropic approximation. Selected
bond distances and angles are listed in Table 2.
2.4. Magnetic measurements
Magnetic susceptibility data of powdered samples
were collected on a MPMS Quantum Design SQUID
magnetometer (XL-5) in the temperature range of
300–1.8 K and at a field of 1000 G. The samples were
placed in a gelatine capsule and a straw was used as
the sample holder. The output data were corrected for
the experimentally determined diamagnetism of the
sample holder and the diamagnetism of the sample cal-
culated from Pascalꢀs constants. The Levenberg–Marqu-
ardt least-squares fitting algorithm, in combination with
MAGPACK [36], was used to model the experimental
magnetic susceptibility data.
2.2.3. Synthesis of [Ni(Pht)(1-MeIm)2(H2O)3] (3)
To a solution of [Ni(1-MeIm)6](HPht)2 Æ 2H2O (0.92
g, 0.1 mmol) in water (10 ml), a solution of NiCl2 Æ 6H2O
(0.24 g, 0.1 mmol) and KOH (0.06 g, 0.1 mmol) in water
(10 ml) was added. The resulting solution was heated at
reflux for two hours. Crystals of 3 suitable for X-ray dif-
fraction studies crystallized after one month and were
collected by filtration, washed with water and EtOH
and dried in air. Yield: 0.56 g, 60.87%. Anal. Calc. for
C16H22N4NiO7: C, 43.56; H, 5.03; N, 12.70. Found: C,
43.42; H, 4.94; N, 12.42%. IR data (KBr, cmꢀ1):
3541sh, 3413m,br, 3147m, 1607sh, 1586sh, 1564s,
3. Results and discussion
3.1. Synthesis and preliminary characterization
Reaction of nickel(II) acetate with o-phthalic acid
and excess of pyridine in water resulted in the high yield
formation of [Ni(Pht)(Py)2(H2O)3] (1). When nickel(II)

S.G. Baca et al. / Inorganica Chimica Acta 358 (2005) 1762–1770
1765
Table 1
Crystal data and details of structural determinations
1
2
3
Empirical formula
Formula weight
Temperature (K)
C18H20N2NiO7
435.07
C20H26N2NiO8
481.14
223(2)
C16H22N4NiO7
441.09
130(2)
130(2)
0.71073
˚
Wavelength (A)
0.71073
0.71073
0.6 · 0.3 · 0.3
triclinic
Crystal size (mm)
Crystal system
Space group
0.6 · 0.5 · 0.15
monoclinic
P21/n
0.5 · 0.35 · 0.2
monoclinic
P21/c
ꢀ
P1
˚
a (A)
15.481(3)
7.272(1)
7.666(1)
7.958(2)
9.244(2)
13.475(3)
107.13(3)
95.87(3)
98.20(3)
926.6(4)
2
˚
b (A)
13.222(1)
21.813(2)
90
˚
c (A)
17.736(4)
90
a (ꢁ)
b (ꢁ)
c (ꢁ)
105.00(3)
90
96.223(1)
90
3
˚
U (A )
1928.6(6)
4
1.498
2198.0(3)
4
1.454
Z
Dc (g cmꢀ3
)
1.581
1.095
460
l (mmꢀ1
F(0 0 0)
)
1.049
904
0.931
1008
h Range for data collection (ꢁ)
Index ranges
3.68–29.60
ꢀ20 6 h 6 20,
ꢀ9 6 k 6 8,
ꢀ23 6 l 6 23
15 413
2.43–25.90
ꢀ9 6 h 6 9,
ꢀ16 6 k 6 1 6,
ꢀ26 6 l 6 26
16 614
3.18–26.37
ꢀ9 6 h6 9,
ꢀ11 6 k 6 10,
ꢀ16 6 l 6 15
7358
Reflections collected
Reflections unique [Rint
]
4934 [0.0278]
91.0
4228 [0.0662]
99.1
3758 [0.0672]
99.1
3758/0/341
Completeness to hmax
Data/restraints/parameters
Final R indices [I > 2r(I)]
R indices (all data)
Goodness-of-fit on F2
4934/0/334
R1 = 0.0270, wR2 = 0.0657
R1 = 0.0296, wR2 = 0.0675
1.025
4228/0/384
R1 = 0.0340, wR2 = 0.0815
R1 = 0.0448, wR2 = 0.0860
0.978
R1 = 0.0350, wR2 = 0.0913
R1 = 0.0397, wR2 = 0.0939
1.097
ꢀ3
˚
Largest difference peak and hole (e A
)
0.389 and ꢀ0.406
0.806 and ꢀ0.394
0.417 and ꢀ0.846
Table 2
acetate reacted with KHPht and excess b-Pic light, a
light green precipitate was initially formed. According
to elemental analysis and IR spectrum, this precipitate
˚
Selected bond distances (A) and bond angles (ꢁ)
1
2
3
1
Ni(1)–O(4)
2.010(1)
2.066(1)
2.073(1)
2.078(1)
2.126(1)
2.075(1)
2.053(1)
2.106(2)
2.099(2)
2.069(2)
2.077(2)
2.095(2)
2.036(2)
2.054(2)
2.076(2)
2.110(1)
2.128(2)
2.080(2)
corresponds to [Ni(Pht)(b-Pic)(H2O)]. Concentration
Ni(1)–N(1A)
Ni(1)–N(1B)
Ni(1)–O(1w)
Ni(1)–O(2w)
Ni(1)–O(3w)
of the filtrate by evaporation gave complex 2,
[Ni(Pht)(b-Pic)2(H2O)3] Æ H2O, in low yield (27%). Com-
plex 3, [Ni(Pht)(1-MeIm)2(H2O)3], is prepared in high
yield (60.87%) by the reaction of nickel(II) salt with
[Ni(1-MeIm)6](HPht)2 Æ 2H2O.
The IR spectra of compounds 1–3 show characteristic
bands of carboxylate groups in the usual region 1608–
1553 cmꢀ1 for asymmetric stretching and in 1405–1399
cmꢀ1 region for symmetric stretching. Their positions
and intensities are similar to those reported for other
phthalates [1,3,8,14,15,28] and carboxylate complexes
[37–39]. The infrared spectra also show broad bands in
the 3541–3071 cmꢀ1 region, which can be assigned to
water molecules.
O(4)–Ni(1)–N(1A)
O(4)–Ni(1)–N(1B)
O(4)–Ni(1)–O(1w)
O(4)–Ni(1)–O(2w)
O(4)–Ni(1)–O(3w)
N(1A)–Ni(1)–N(1B)
N(1A)–Ni(1)–O(1w)
N(1A)–Ni(1)–O(3w)
N(1A)–Ni(1)–O(2w)
N(1B)–Ni(1)–O(1w)
N(1B)–Ni(1)–O(3w)
N(1B)–Ni(1)–O(2w)
O(1w)–Ni(1)–O(2w)
O(3w)–Ni(1)–O(1w)
O(3w)–Ni(1)–O(2w)
170.95(4)
91.70(5)
85.59(4)
83.13(4)
92.56(4)
90.59(5)
92.28(5)
96.16(5)
88.01(4)
177.02(4)
90.61(4)
92.93(4)
88.00(4)
88.26(4)
174.50(4)
170.35(6)
92.45(6)
84.31(6)
85.76(6)
91.66(6)
95.66(6)
87.72(6)
94.11(7)
89.24(7)
176.38(6)
86.14(6)
88.34(6)
93.02(6)
92.33(6)
173.80(6)
176.93(5)
89.31(6)
82.56(6)
83.25(6)
90.51(6)
93.60(7)
94.51(7)
90.51(6)
95.70(6)
171.81(6)
89.31(6)
91.06(6)
87.05(6)
91.71(6)
173.74(5)
The thermogravimetric analyses of compounds 1 and
2 indicated a sharp mass loss, followed by a long tail,
1
Anal. Calc. for C14H13NNiO5: C, 50.35; H, 3.92; N, 4.19. Found:
C, 50.60; H, 3.76; N, 4.16%. IR data (KBr, cmꢀ1): 3411s,br, 1642vs,
1610vs, 1589sh, 1562vs, 1488s, 1446s, 1415vs, 1199w, 1163w, 1131w,
1112w, 1086w, 1060m, 1038m, 859m, 822s, 792m, 769m, 748m, 697s,
655s, 469w.
with total mass loss of 82.88% and 84.59% in the range
25–450 ꢁC, which is in agreement with the mass loss cal-
culated for the loss of both water molecules and organic

1766
S.G. Baca et al. / Inorganica Chimica Acta 358 (2005) 1762–1770
moieties (Calc. 82.78% and 84.43%). For compound 3, a
mass loss of 12.28% in the 25–130 ꢁC temperature range
corresponds to the loss of three coordinated water mol-
ecules for the formula units (Calc. 12.26%) and the sec-
ond mass loss of 69.49% corresponds to the loss of the
organic moieties (Calc. 70.76%).
group of o-phthalic acid [24–28]. In all three com-
pounds, nickel atoms have octahedral coordination
geometry. Two cis-positions in the coordination polyhe-
dron are occupied by two nitrogen atoms of aromatic
amines with the Ni–N distances of 2.066(1) and
˚
˚
2.073(1) A (1), 2.099(2) and 2.106(2) A (2), and
˚
2.054(2) and 2.076(2) A (3). The dihedral angle between
3.2. Crystal structures
the aromatic rings is 117.2(2)ꢁ for 1, 106.6(2)ꢁ for 2 and
90.1(2)ꢁ for 3. The phthalate ligand is coordinated to the
nickel atom in a monodentate fashion and occupies
one place in the octahedron with bond distances
The structures of compounds 1–3 (Fig. 1(a)–(c)) are
similar to structures of molecular compounds with
monodentate coordination mode of one carboxylate
˚
Ni–O(4) = 2.010(1), 2.053(1) and 2.036(2) A for 1–3,
(a)
(b)
(c)
Fig. 1. Crystallographically independent structure fragments with numbering scheme and displacement ellipsoids drawn at the 50% probability level
in compounds [Ni(Pht)(Py)2(H2O)3] (1a), [Ni(Pht)(b-Pic)2(H2O)3] Æ H2O (1b) and [Ni(Pht)(1-MeIm)2(H2O)3] (1c).

S.G. Baca et al. / Inorganica Chimica Acta 358 (2005) 1762–1770
1767
respectively. Finally, the coordination sphere is com-
pleted by oxygen atoms of three water molecules. The
Ni–O(w) distances vary in the range of 2.069(2)–
drated Ni(II) complexes with monocoordinated o-
phthalic acid.
Interestingly, the intermolecular O(w)–Hꢁ ꢁ ꢁO(carb.)
hydrogen interactions are very important in the con-
struction of the crystal edifice of 1–3. In compound 1,
water molecules O(1w) and O(2w) are involved in both
the formation of intramolecular pseudo-cycles with
O(1) and O(2) oxygen atoms of phthalate carboxylate
groups and the hydrogen bonding with identical oxygen
atoms on the adjacent complex (symmetry code [ꢀx ꢀ 2,
ꢀy ꢀ 1, ꢀz]) (Table 3). As a consequence, individual
molecules are joined into centrosymmetric dimers as
shown in Fig. 2(a) with Mꢁ ꢁ ꢁM distances of 6.570(1)
˚
2.128(2) A (Table 2).
The presence of water molecules and carboxyl groups
makes extensive hydrogen bonding interactions in com-
pounds 1–3, which are listed in Table 3. Fig. 1(a)–(c)
illustrates intramolecular hydrogen bonds of O(w)–
Hꢁ ꢁ ꢁO type in these compounds. They are identical for
1 and 3 and differ slightly for 2 by reason of presence
of the solvate water molecule O(4w).
The water molecule O(3w) and carboxylate oxygen
atom O(3) form the hydrogen bond O(3w)–
˚
˚
˚
Hꢁ ꢁ ꢁO(3) = 2.714(2) A (1), 2.753(2) A (2), and 2.664(2)
A. Hydrogen bonds O(3w)–Hꢁ ꢁ ꢁO(1) connect adjacent
˚
A (3), leading to the organization of the six-membered
dimers in double-chains along the y-axis of the unit cell
of 1 (Fig. 2(b)). Distance between metals of the adjacent
Ni(1)–O(3w)–Hꢁ ꢁ ꢁO(3)–C(22)–O(4)–Ni(1)
hydrogen
˚
dimers is 7.272(1) A. In compounds 2 and 3, water mol-
bonded ring. The coordinated water molecules O(1w)
and O(2w) take part in the formation of 9-membered
hydrogen bonded rings Ni(1)–O(1w)–Hꢁ ꢁ ꢁO(2)–C(11)–
C(1)–C(2)–C(22)–O(4)–Ni(1) in all title compounds
and Ni(1)–O(2w)–Hꢁ ꢁ ꢁO(1)–C(11)–C(1)–C(2)–C(22)–
O(4)–Ni(1) only in 1 and 3. The corresponding distances
ecules O(1w), O(2w) and O(3w) adopt the same role and
form analogous double chains. The Mꢁ ꢁ ꢁM distances in
˚
the dimers are 6.421(1) A for 2 and 6.930(1) A for 3, and
˚
˚
between dimers are 7.666(1) and 7.958(1) A for 2 and 3,
respectively. The solvate molecule O(4w) in 2 gives rise
to hydrogen bonds only inside the double-chain. Fur-
thermore, similar double-chains are observed in all the
above noted Ni-compounds with monodentate phtha-
lates [24–28]. Depending on the nature of aromatic
amines, the arrangement of these chains differs between
crystals. The double-chains are held together only by
˚
˚
are 2.830(2) (1), 2.906(2) A (2) and 2.917(2) A (3), and
˚
O(2w)–Hꢁ ꢁ ꢁO(1) distances are 2.993(2) and 3.316(2) A
for 1 and 3, respectively. In 2, the water molecule
O(2w) is only involved in intermolecular H-bonding
(Fig. 1(b), Table 3). Similar intramolecular hydrogen
bonding pattern was observed in the structures of all hy-
Table 3
Hydrogen bonding interaction in the crystal structures 1–3
˚
Distances (A)
D–Hꢁ ꢁ ꢁA
Symmetry operation generating A
Angles (ꢁ)
D–H
Hꢁ ꢁ ꢁA
Dꢁ ꢁ ꢁA
Compound 1
O(1w)–H(1w2)ꢁ ꢁ ꢁO(1)
O(1w)–H(1w1)ꢁ ꢁ ꢁO(2)
O(2w)–H(2w1)ꢁ ꢁ ꢁO(1)
O(2w)–H(2w2)ꢁ ꢁ ꢁO(2)
O(3w)–H(3w2)ꢁ ꢁ ꢁO(3)
O(3w)–H(3w1)ꢁ ꢁ ꢁO(1)
ꢀx ꢀ 2, ꢀy ꢀ 1,ꢀz
0.80(2)
0.83(2)
0.80(2)
0.82(3)
0.81(2)
0.86(2)
1.89(3)
2.00(2)
2.20(2)
1.97(3)
1.92(2)
1.91(2)
2.693(2)
2.830(2)
2.993(2)
2.785(1)
2.714(2)
2.765(1)
174(2)
176(2)
171(2)
178(2)
166(2)
174(2)
ꢀx ꢀ 2,ꢀ y ꢀ 1, ꢀz
x, y ꢀ 1,z
Compound 2
O(1w)–H(1w2)ꢁ ꢁ ꢁO(1)
O(1w)–H(1w1)ꢁ ꢁ ꢁO(2)
O(2w)–H(2w1)ꢁ ꢁ ꢁO(4w)
O(2w)–H(2w2)ꢁ ꢁ ꢁO(2)
O(3w)–H(3w2)ꢁ ꢁ ꢁO(3)
O(3w)–H(3w1)ꢁ ꢁ ꢁO(2)
O(4w)–H(4w1)ꢁ ꢁ ꢁO(1)
O(4w)–H(4w2)ꢁ ꢁ ꢁO(3)
ꢀx,ꢀy + 1, ꢀz
0.87(3)
0.81(3)
0.87(3)
0.85(4)
0.91(3)
0.84(3)
0.87(4)
0.90(3)
1.83(3)
2.11(3)
1.96(3)
1.86(4)
1.87(3)
1.92(3)
1.92(4)
1.87(3)
2.699(2)
2.906(2)
2.817(2)
2.700(2)
2.753(2)
2.723(2)
2.757(2)
2.755(2)
177(3)
168(2)
169(2)
170(4)
161(3)
157(3)
162(3)
169(3)
ꢀx, ꢀy + 1, ꢀz
ꢀx + 1 ,ꢀy + 1, ꢀz
xꢀ1, y, z
Compound 3
O(1w)–H(1w1)ꢁ ꢁ ꢁO(1)
O(1w)–H(1w2)ꢁ ꢁ ꢁO(2)
O(2w)–H(2w2)ꢁ ꢁ ꢁO(2)
O(2w)–H(2w1)ꢁ ꢁ ꢁO(1)
O(3w)–H(3w2)ꢁ ꢁ ꢁO(1)
O(3w)–H(3w1)ꢁ ꢁ ꢁO(3)
ꢀx + 1, ꢀy + 1, ꢀz
ꢀx + 1, ꢀy + 1, ꢀz
x ꢀ 1, y, z
0.82(3)
0.76(3)
0.79(3)
0.87(3)
0.78(3)
0.82(3)
1.90(3)
2.17(3)
1.93(3)
2.47(3)
2.00(3)
1.89(3)
2.711(2)
2.917(2)
2.716(2)
3.316(2)
2.776(2)
2.664(2)
168(3)
170(3)
172(3)
163(2)
175(3)
158(3)

1768
S.G. Baca et al. / Inorganica Chimica Acta 358 (2005) 1762–1770
(a)
Fig. 3. Fragment of the crystal structure of compound 2 showing the
double chains formed by hydrogen bonding and p-stacking interaction
between them (centroid–centroid distance X(1A)–X(1B) is equal
˚
3.791(2) A).
(b)
Fig. 2. (a) The hydrogen bonded centrosymmetric dimer in 1. (b) The
view of double-chains in this compound. Hydrogen atoms are omitted
for the sake of clarity and hydrogen bonds are indicated by dotted
lines.
van der Waals interactions in compound 1 (Fig. 3). In
contrast, in 2 these chains form layers parallel to the
y-axis by p–p interactions between antiparallel mole-
cules of b-Pic (Fig. 4) with an average distance between
˚
aromatic rings of 3.38 A and a centroid–centroid dis-
˚
tance of 3.791(2) A. In addition, the layers are inter-
linked together into a network by p–p interactions
between b-Pic and Pht rings, the average contact dis-
˚
tance of two adjacent aromatic rings is about 3.48 A
˚
and the centroid–centroid distance is 3.868(2) A. The
dihedral angle between the aromatic rings is 7.2(2)ꢁ. In
complex 3, the double-chains are knitted together via
C(31b)–Hꢁ ꢁ ꢁO(4) [ꢀx + 1, ꢀy + 1, ꢀz + 1] hydrogen
˚
bonds of 3.342(3) A between the methyl group of 1-
MeIm and the coordinated carboxylate oxygen atom,
as well as p–p contacts involving antiparallel 1-MeIm
˚
cycles (centroid–centroid distance is 3.719(3) A) to build
up layers parallel to the xz-plane as depicted in Fig. 4.
Fig. 4. Crystal packing perspective view of 3 showing supramolecular
weak aromatic p–p stacking interactions and C–Hꢁ ꢁ ꢁO hydrogen-
bonding.

S.G. Baca et al. / Inorganica Chimica Acta 358 (2005) 1762–1770
1769
4. Magnetic properties
2.4
The thermal dependence of vMT (vMT being the
product of the molar magnetic susceptibility and the
temperature) and the simulated curves for powdered
samples of the hydrogen bonded dimeric nickel com-
pounds 1–3 are shown in Figs. 5–7. The molar magnetic
susceptibilities have been corrected for their diamagnetic
and temperature independent paramagnetic (TIP) con-
tributions. For compound 1, the TIP is 9 · 10ꢀ4 emu/
mol. The vMT values remain essentially constant at
2.45 emu K/mol between 300 and 100 K. This value
agrees well with the expected 2.42 emu K/mol for two
uncoupled Ni2+ ions with S = 1 and g = 2.2. Below 100
K, vMT decreases due to zero-field splitting and weak
antiferromagnetic interaction between the Ni2+ ions.
The simulation with a g-value of 2.22, an axial zero-field
splitting parameter |D| = 4.11 cmꢀ1 and an antiferro-
magnetic interaction parameter J = ꢀ0.29 cmꢀ1, agreed
best with the experimental data. Similarly, the vMT val-
ues of compound 2 (TIP = 9 · 10ꢀ4 emu/mol) remain
constant at 2.47 emu K/mol down to 100 K and decrease
at lower temperatures. A simulation of the magnetic
data for this compound resulted in g = 2.215,
|D| = 3.85 cmꢀ1 and J = ꢀ0.1 cmꢀ1. For compound 3
(TIP = 9.6 · 10ꢀ4 emu/mol), the experimental value of
vMT is 2.50 emu K/mol at room temperature. In con-
trast to compounds 1 and 2, the values of vMT of com-
pound 3 increase below 100 K, suggesting ferromagnetic
interaction between the Ni2+ ions. These data could be
simulated best with the corresponding parameters
g = 2.23, J = 0.22 cmꢀ1 and |D| = 4.6 cmꢀ1. Overall, all
three compounds exhibit weak magnetic exchange inter-
actions and subtle structural differences may cause a
2.2
2.0
1.8
1.6
50
100
150
T/ K
200
250
300
Fig. 6. Temperature dependence of vMT for compound 2. The circles
correspond to the experimental data, the simulation is depicted as a
line.
2.4
2.2
2.0
1.8
2.4
2.2
2.0
1.8
1.6
1.4
1.2
50
100
150
T/ K
200
250
300
Fig. 7. Temperature dependence of vMT for compound 3. The circles
correspond to the experimental data, the simulation is depicted as a
line.
change from a total antiferromagnetic interaction to a
ferromagnetic type of interaction as it is seen for com-
pound 3. However, the structural aspects are too com-
plex to render a conclusive structure–property relation.
5. Supplementary material
50
100
150
200
250
300
T/ K
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 232778 (1), 232777 (2) and
232776 (3). Copies of this information may be obtained
Fig. 5. Temperature dependence of vMT for compound 1. The circles
correspond to the experimental data, the simulation is depicted as a
line.

1770
S.G. Baca et al. / Inorganica Chimica Acta 358 (2005) 1762–1770
[15] S.G. Baca, I.G. Filippova, N.V. Gerbeleu, Yu.A. Simonov, M.
Gdaniec, G.A. Timco, O.A. Gherco, Yu.L. Malaestean, Inorg.
Chim. Acta 344 (2003) 109.
from The Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (fax: +44 1233 336033; e-mail: depos-
it@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk).
[16] J.W. Bats, A. Kallel, H. Fuess, Acta Crystallogr., Sect. B 34
(1978) 1705.
[17] R.C. Squire, S.M.J. Aubin, K. Folting, W.E. Streib, D.N.
Hendrickson, G. Christou, Angew. Chem. Int., Ed. Engl. 34
(1995) 887.
Acknowledgment
[18] R.C. Squire, S.M.J. Aubin, K. Folting, W.E. Streib, G. Christou,
D.N. Hendrickson, Inorg. Chem. 34 (1995) 6463.
[19] C. Can˜ada-Vilalta, M. Pink, G. Christou, J. Chem. Soc., Dalton
Trans. (2003) 1121.
This work was supported by the Swiss National Sci-
ence Foundation (SCOPES 7MDPJ065712.01/1).
[20] E.K. Brechin, R.O. Gould, S.G. Harris, S. Parsons, R.E.P.
Winpenny, J. Am. Chem. Soc. 118 (1996) 11293.
[21] E.K. Brechin, S.G. Harris, S. Parsons, R.E.P. Winpenny, J.
Chem. Soc., Chem. Commun. (1996) 1439.
References
[22] E.K. Brechin, A. Graham, A. Parkin, S. Parson, A.M.
Seddon, R.E.P. Winpenny, J. Chem. Soc., Dalton Trans.
(2000) 3242.
[1] S.G. Baca, I.G. Filippova, O.A. Gherco, M. Gdaniec, Yu.A.
Simonov, N.V. Gerbeleu, P. Franz, R. Basler, S. Decurtins,
Inorg. Chim. Acta 357 (2004) 3419.
[23] G.B. Shulꢀpin, G. Suss-Fink, L.S. Shulꢀpina, J. Mol. Catal. 170
¨
(2001) 17.
[24] G. Adiwidjaja, H. Kuppers, Acta Crystallogr., Sect. B 32 (1976)
1571.
[2] F.H. Allen, Acta Crystallogr., Sect. B 58 (2002) 380.
[3] S.G. Baca, Yu.A. Simonov, M. Gdaniec, N.V. Gerbeleu, I.G.
Filippova, G.A. Timco, Inorg. Chem. Commun. 6 (2003) 685.
[4] M.B. Cingi, C. Guastini, A. Musati, N. Nardelli, Acta Crystal-
logr., Sect. B 26 (1970) 1836.
[25] N.P. Kozlova, V.M. Agre, V.K. Trunov, S.S. Makarevich, N.N.
Barkhanova, Russ. J. Struct. Chem. 23 (1982) 108.
[26] D. Poleti, D.R. Stojakovic, B.V. Prelesnik, Lj. Manojlovic-Muir,
Acta Crystallogr., Sect. C 46 (1990) 399.
[5] (a) M.B. Cingi, A.M.M. Lanfredi, A. Tiripicchio, M.T. Camellini,
Acta Crystallogr., Sect. B 33 (1977) 659;
[27] D. Poleti, L. Karanovic, B.V. Prelesnik, Acta Crystallogr., Sect. C
46 (1990) 2465.
(b) M.B. Cingi, A.M.M. Lanfredi, A. Tiripicchio, M.T. Camellini,
Acta Crystallogr., Sect. B 34 (1978) 412.
[28] F.-C. Xue, Z.-H. Jiang, D.-Z. Liao, S.-L. Ma, S.-P. Yan, G.-L.
Wang, X.-K. Yao, R.-J. Wang, Polyhedron 12 (1993) 2787.
[29] H. Endres, Z. Anorg. Allg. Chem. 513 (1984) 78.
[30] M.B. Cingi, A.M.M. Lanfredi, A. Tiripicchio, Acta Crystallogr.,
Sect. C 40 (1984) 56.
[6] I. Krstanovic, Lj. Karanovic, Dj. Stojakovic, Acta Crystallogr.,
Sect. C 41 (1985) 43.
[7] B.L. Rodrigues, M.D.D. Costa, N.G. Fernandes, Acta Crystal-
logr., Sect. C 55 (1999) 1997.
[8] (a) N.V. Gerbeleu, Y.u.A. Simonov, G.A. Timko, P.N. Bourosh,
J. Lipkowski, S.G. Baka, D.I. Saburov, M.D. Mazus, Russ. J.
Inorg. Chem. 44 (1999) 1191;
[31] Z. Tomic, B. Prelesnik, L. Karanovic, D. Poleti, J. Serb. Chem.
Soc. 61 (1996) 97.
[32] XEMP Ver. 4.2 Siemens Analytical X-ray Inst. Inc., 1990.
[33] Stoe & Cie IPDS Software. Stoe & Cie GmbH, Darmstadt,
Germany, 2000.
(b) S.G. Baca, S.T. Malinovskii, P. Franz, Ch. Ambrus, H.
Stoeckli-Evans, N. Gerbeleu, S. Decurtins, J. Solid State Chem.
177 (2004) 2841.
[34] G.M. Sheldrick, SHELXS-97 Program for the Solution of Crystal
Structures, University of Goettingen, Germany, 1997.
[35] G.M. Sheldrick, SHELXL-97, Program for the Refinement of
Crystal Structures, University of Goettingen, Germany, 1997.
[9] Y. Zhang, J. Li, Q. Su, Q. Wang, X. Wu, J. Mol. Struct. 516
(2000) 231.
[10] P. Lightfoot, A. Snedden, J. Chem. Soc., Dalton Trans. (1999)3549.
[11] E. Suresh, K. Boopalan, R.V. Jasra, M.M. Bhadbhade, Inorg.
Chem. 40 (2001) 4078.
´
[36] J.J. Borras-Almenar, J.M. Clemente-Juan, E. Coronado, B.S.
Tsukerblatt, Inorg. Chem. 38 (1999) 6081.
[12] Yu.A. Simonov, M. Gdaniec, I.G. Filippova, S.G. Baca, G.A.
Timco, N.V. Gerbeleu, Russ. J. Coord. Chem. 27 (2001) 353.
[13] A.D. Burrows, R.W. Harrington, M.F. Mahon, C.E. Price, J.
Chem. Soc., Dalton Trans. (2000) 3845.
[37] G.B. Deacon, R.J. Phillips, Coord. Chem. Rev. 33 (1980) 227.
[38] K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds, Wiley, New York, 1986, p. 236.
[39] R.C. Mehrotra, R. Bohra, Metal Carboxylates, Academic Press,
New York, 1983, p. 48.
[14] S.G. Baca, Yu.A. Simonov, N.V. Gerbeleu, M. Gdaniec, P.N.
Bourosh, G.A. Timco, Polyhedron 20 (2001) 831.