Hexaco-ordination of a diamino-substituted tetra-azameacrocycle to cobalt(III) and nickel(II): compressed Co–N bonds?
Abstract
The substituted cyclam macrocycle 6,13-diamino-6,13-dimethyl-1,4,8,11-tetra-azacyclotetradecane (L2) can co-ordiante to metal ions as a hexadentate ligand; whereas M–N distances for the NiII complex are ‘normal,’ those for the CoIII complex are unusually short, and this is reflected in a very negative CoIII/II redox couple and a significant shift of the electronic spectrum mmaxima to higher energy.