Binuclear complexes of the
types CuB,CuCl2, CuB,ZnCl2,
ZnB,ZnCl2, and
CuL2,CuCl2 have been obtained where BH2 is a
quadridentate Schiff base derived from salicylaldehyde
and a polyrnethylenediamine and LH is an N-alkylsalicylaldimine. The stereochemistry of the copper atoms in the
binuclear complexes is inferred from comparisons of their reflectance spectra
with the spectra of the simple copper complexes CuB
and CuL2. The structures of the zinc
complexes are discussed by reference to near ultraviolet spectra of the ligands
and infrared spectra in the 1500-1560 cm-1 region. The evidence suggests that
in the complexes of the type MB,M'Cl2
either but not both metal atoms may approach a tetrahedral environment. The
chemistry of the complexes ZnB,ZnCl2 is
complicated by the possibility of either or both zinc atoms becoming 5 coordinate
by addition of solvent molecules; in some of these complexes the zinc chloride
appears to be attached to a solvent molecule in a 5-coordinate Schiff base
unit, rather than by bridging through phenolic oxygen atoms. The oomplexes
CuL2,CuCl2 apparently have a
symmetrical binuclear structure based on a trans arrangement of the Schiff base
units rather than an unsymmetrical structure resembling that of the complexes CuB,CuCl2. Complexes of the types CuL2,ZnCl2 and ZnL2,ZnCl2
could not be obtained.
The relationship between the strength of hydrogen bonding and spin crossover behaviour in a series of iron(iii) Schiff base complexes