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The crystal structure of the complex 17 was solved in this work. Complex 17 crystallized with
two discrete cobalt(II) complexes and one solvent molecule in the asymmetric unit cell. The
coordination sphere around the cobalt can be roughly classified as distorted trigonal
bipyramid in which the imino nitrogens of the ligand occupy the axial positions, and two
chlorines and the nitrogen atom of the pyridine form the trigonal plane. Trigonal bipyramid
describes well the C 2 -symmetry of this molecule when the pyridine nitrogen and the cobalt
atom are chosen for as the rotation axis.
The solid state structure of 17 is closely related to the structure described by Britovsek et al.
for the 2,6-bis[(2,6-diisopropylphenylimino)ethyl]pyridine cobalt(II) complex (BPEP-
Co(II)). [ 16]
A clear difference in the geometry of the two complexes is the location of the
cobalt in respect of the N 3 -plane. In the Co complex of reference [16], the cobalt deviates
from the plane by 0.56 Å, whereas in 17 the corresponding deviations are only 0.0706(3) Å
and 0.0278(3) Å. We assume that this difference is due to the change of the imino substituents
from aromatic to aliphatic. In addition, the ligand framework of 17 is twisted, as can be seen
in the side-view presented in Figure 4. The imino nitrogens are shifted to opposite sides of the
mean plane, established by the pyridine and the cobalt center.
Figure 4. Solid state structure of 17. The second cobalt complex and the solvent molecule and
hydrogen atoms are omitted for clarity. [VI]
2.2. Palladium Complexes with Nitrogen, Phosphorus, Sulfur and Arsene Donor Atoms
Palladium(II) complexes with symmetrical bidentate P- or N-donor ligands are well-known
and their catalytic activity has been widely investigated. [ 8]
At the same time, research on
asymmetrical complexes with mixed donor atoms e.g., ligands bearing P and S or N as donor
atoms, has been insignificant. A general feature of the coordination chemistry of complexes
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