MOSSBAUER STUDY OF THE INFLUENCE OF LIGAND AND ANIONS OF THE 2ND COORDINATION SPHERE IN FE(II) COMPLEXES WITH 1,2,4-TRIAZOLE AND 4-AMINO-1,2,4,-TRIAZOLE ON THE TEMPERATURE OF THE (1)A(1)REVERSIBLE-ARROW-T-5(2)SPIN TRANSITIONS

For Fe(II) complexes with 1,2,4-triazole (Tr) and 4-amino-1,2,4-triazo l (ATr) in low-spin phases, if has been revealed that the ligand and a nion of the second coordination sphere affect the electronic stale of the central atom and the symmetry of its local environment For low-spi n phases, a correlation between the Mossbauer spectrum parameters - th e chemical shift and the bandwidth of the weakly resolved quadrupole d oublet - and the spin transition temperature T-C has been established the mechanism of the influence of complex composition on the spin tran sition temperature is accounted for by assuming that T-C is determined by the lattice energy of a complex compound.