Syntheses, structures, and properties of two mononuclear cobalt(III) azido complexes containing a tetradentate N-donor Schiff base as end-capping ligand

Two hexacoordinated mononuclear Co(III) compounds of the type cis-[Co(L)(N-3)(2)] X [1, X = ClO4; 2, X = PF6; L = N,N'-(bis(pyridine-2-yl)benzylidine)-1,4-butanediamine] have been synthesized and characterized by physicochemical and spectroscopic methods. The crystal structures of complexes 1 and 2 both have distorted octahedral geometry with two terminal azides in mutual cis orientations. In the crystalline state, two mononuclear units of 1 are associated by weak C-HaEuro broken vertical bar pi interactions to produce a dimeric unit, which packs through C-HaEuro broken vertical bar O hydrogen bonds and pi aEuro broken vertical bar pi interactions leading to a 2-D continuum. The mononuclear units in 2 are engaged in weak cooperative intermolecular C-HaEuro broken vertical bar pi interactions and multiple C-HaEuro broken vertical bar F hydrogen bonds giving rise to a 3-D network structure. These diamagnetic compounds are redox active and show luminescence in DMF solutions.