Cyanoscorpionates: Co(II), Mn(II), and Ni(II) complexes coordinated only through the cyano group

Abstract

New complexes have been synthesized of scorpionate ligands with cyano substituents in the 4-positions of the pyrazoles and tert-butyl substituents in the 3-positions of the pyrazoles. Reaction of Co 2+, Mn 2+, and Ni(cyclam) 2+ (cyclam = 1,4,8,11-tetraazacyclotetradecane) with Tp t- Bu,4CN in a 1:2 ratio produced new octahedral metal complexes of the form (Tp t -Bu,4CN) 2ML 4 (L 4 = (H 2O) 4, (H 2O) 2(MeOH) 2, or cyclam). Unlike the sandwich complexes previously isolated with Tp Ph,4CN, the crystal structures showed none of the pyrazole nitrogen atoms coordinated to the metal. Rather, the metal is coordinated to one CN nitrogen atom from each ligand, with two Tp anions coordinated trans to each other around the metal center. This leaves the Tp pyrazole nitrogen atoms open for another metal to coordinate, which could to lead to heterometallic complexes, new coordination polymers, as well as the framework for supramolecular complexes.