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C.-Y. Sun, L.-P. Jin / Polyhedron 23 (2004) 2227–2233
1
1
613s, 1565m, 1537m, 1478w, 1402m, 1378m, 1310m,
295m, 816w, 661w, 608w.
2
.3. X-ray diffraction determination
Diffraction intensities for the four complexes were
collected at 293 K on a Bruker SMART 1000 CCD dif-
fractometer employing graphite monochromatized Mo
˚
Fig. 1. The coordination environment of the Co(II) ion in complex 1
with 50% thermal ellipsoids.
Ka radiation (k = 0.71073 A). A semi-empirical absorp-
tion correction was applied using the SADABS program
[21]. The structures were solved by direct methods [22]
2
and refined by full-matrix least squares on F using
a
SHELXS-97 and SHELXL-97 programs, respectively
[
22,23]. Non-hydrogen atoms were refined anisotropi-
b
cally. All hydrogen atoms were initially located in a dif-
ference Fourier map. The O–H distances were then fixed
B
˚
at 0.85 A and Uiso(H) of the hydrogen atoms of H O
2
c
e
A
d
was 1.5 times of Ueq(O) in the next refinement. The
crystallographic data for complexes 1–4 are listed in
e
c
d
B
˚
Table 1, and selected bond lengths (A) and bond angles
b
(
ꢁ) in Tables 2 and 3.
a
3
. Results and discussion
Fig. 2. 3D network constructed by hydrogen bonds of complex 1
viewed along the a axis, all hydrogen atoms are omitted for clarity.
3
.1. Description of the structures
Complexes 1 and 2, 3 and 4 are two isomorphous
atom), resulting in the formation of a 3D-supramoleclar
structure (see Fig. 2). There are two kinds of channels (A
and B) in the structure, but they are too small for any
host molecules to reside. The geometry of the hydrogen
bonds is shown in Table 4. There is a weak p–p stacking
interaction between the pyramidine rings at a distance of
pairs. Because of the different radii of the Co(II) and
Ni(II) ions, there are corresponding differences in the
distances of M–O and M–N (M = Co or Ni), but only
the structures of 1 and 3 will be described in detail.
˚
3
.1.1. [Co(Hiso)(H O) ] (1)
2
3.76 A, which stabilizes the complex.
3 n
As shown in Fig. 1, the Co(II) ion is six-coordinated
2
and surrounded by two oxygen atoms from one Hiso
ꢀ
2
anion, one nitrogen atom from another Hiso anion
ꢀ
3.1.2. {[Co (Hiso) (bipy) (H O) ] Æ 2(bipy)} (3)
2
2
2
2
4
n
2
ꢀ
and three aqua ligands. In this complex the Hiso an-
ion acts as a tridentate ligand through O(1), O(3) and
N(2). This kind of coordination mode has not been re-
There are two kinds of metal coordination environ-
ments in 3, as shown in Fig. 3. Although Co(1) and
Co(2) are both six-coordinate and their coordination
geometries can be described as distorted octahedrons,
the coordination environments around them are differ-
ent. Co(1) is coordinated by four oxygen atoms belonging
2
ꢀ
ported before. The bridging Hiso
Co(II) ions into infinite polymeric zigzag chains parallel
anions link the
to the c-axis. The Coꢁ ꢁ ꢁCo distance in the chain is 7.574
2
ꢀ
˚
˚
A (7.488 A for Ni) and the Co–Co–Co angle is 151.2ꢁ
to two Hiso anions and two nitrogen atoms from two
bipy molecules, while Co(2) is coordinated by two nitro-
gen atoms of bipy and four aqua ligands. Co(1) and Co(2)
are in the center of symmetry and are connected by bipy
(
151.5ꢁ for Ni).
In 1, the amido groups, the carbonyl oxygen atoms,
the carboxylate groups and the aqua ligands are all in-
volved in hydrogen bonds. The amido groups and the
aqua ligands act as hydrogen bonding donors, while
the carboxylate and the carbonyl oxygen atoms act as
hydrogen bonding acceptors. There are O –Hꢁ ꢁ ꢁO
˚
˚
at a separation of 11.365 A (11.288 A for Ni). In complex
2
3, the Hiso anion acts as a bidentate ligand through
ꢀ
O(1) and O(3). It is worth noting that although N(2) in
2
ꢀ
the Hiso anion is deprotonated, it is not coordinated
as in 1 and 2 owing to the strong coordination ability
of bipy to Co(II) ions. There are two kinds of bipy that
have different roles in the structure (see Fig. 3). One kind
of bipy bridges Co(II) ions and the dihedral angle of the
two pyridine rings of this bipy is 6.1ꢁ; while the other
w
w
(
a), O –Hꢁ ꢁ ꢁO (b), O –Hꢁ ꢁ ꢁO (c), O –Hꢁ ꢁ ꢁO (d)
c
w
cc
w
uc
w
c
and N–Hꢁ ꢁ ꢁO (e) hydrogen bonds between the chains
(
carboxyl oxygen atom; O , uncoordinating carboxyl
O , water molecule oxygen atom; O , coordinating
w cc
uc
oxygen atom; O , uncoordinating carbonyl oxygen
c