COORDINATION GEOMETRIES AND COOPERATIVE ORDERING EFFECTS IN COPPER(II) COMPLEXES WITH TRIDENTATE SCHIFF-BASE DIANIONS - VI - STRUCTURE AND EPR-SPECTRA OF (IMIDAZOLE) (N-SALICYLIDENE-BETA-ALANINATO) COPPER(II)
G. Plesch et al., COORDINATION GEOMETRIES AND COOPERATIVE ORDERING EFFECTS IN COPPER(II) COMPLEXES WITH TRIDENTATE SCHIFF-BASE DIANIONS - VI - STRUCTURE AND EPR-SPECTRA OF (IMIDAZOLE) (N-SALICYLIDENE-BETA-ALANINATO) COPPER(II), Polyhedron, 17(4), 1998, pp. 539-545
The crystal and molecular structure of (imidazole) (N-salicylidene-bet
a-alaninato)copper(III), monoclinic, space group C/2c, was solved by a
single crystal X-ray structure analysis and refined to R = 0.0577 for
1286 observed reflections. The coordination polyhedron around Cu(II)
is an axially elongated square-pyramid, the basal plane being formed b
y the (O, N, O) atoms of the tridentate Schiff base and the N atom of
imidazole. The apex of-the pyramid is occupied by the terminal carboxy
lic atom of adjacent molecule, thereby giving rise to centrosymmetric
dimers. Non-parallel aligned stacks of dimeric units are propagated in
the unit cell. The powder and single-crystal EPR spectra show coopera
tive g factors resulting from the weak coupling between two misaligned
g tensors from dimeric units ordered in a disturbed-ferrodistortive w
ay. Since the N-N axes, corresponding to g(y), are oriented nearly par
allel; the g-g coupling shifts only the values of g(z) and g(x). A com
plete consistency between the angular spectroscopic EPR behaviour and
the X-ray structural data was found. (C) 1998 Elsevier Science Ltd. Al
l rights reserved.