Trinuclear complexes of four-coordinate iron and cobalt:: Some reflections on the importance of the reaction conditions for the formation of metal–metal bonds

Abstract

The mononuclear, tetrahedral iron and cobalt complexes, FeCl 2(Hhpp) 2, I, and CoCl 2(Hhpp) 2, II, are readily formed by the reaction of the metal (II) chloride with Hhpp. Compound II crystallized as blue blocks in the space group Fdd2. The reaction of I with LiMe yielded the trinuclear complex Fe 3Cl 2(hpp) 4, III, which crystallized as colorless blocks in the space group P2 1/n. A cobalt complex Co 3Cl 2(hpp) 4, IV, analogous to III, was synthesized by the reaction of CoCl 2 with Lihpp. Compound IV crystallized as blue blocks in the space group P2 1. Both III and IV have three four-coordinate metal centers and contain no metal–metal bonds, two metal atoms are each bound to one chlorine and three nitrogen atoms while the third one is bound to four nitrogen atoms.