NEW IRON(II) COMPLEXES OF C-3-CYCLOTRIVERATRYLENE LIGANDS EXHIBITING SPIN-STATE TRANSFORMATIONS

We report preliminary results on the synthesis and magnetic properties of a new family of pseudo-octahedral Fe(II) complexes of racemic C-3- cyclotriveratrylene ligands provided with iminopyridine (L1), 5-methyl -1-iminopyridine (L2) and 4,4'-disubstituted bipyridine (L3,L4) bindin g sites. The spin state of these complexes is found to depend not only on the ligand, but also on the nature of the counter anion. The cryst al structure of [Fe(II)L1](PF6)(2) in which both high spin and low spi n states co-exist in a constant 1:5 ratio in the range 6-300 K indicat es the existence of two independent crystallographic sites and suggest s that the high spin fraction is preferentially localized at one of th ese sites.