Structure and magnetism of a mixed-valence octanuclear manganese(ii/iii) cluster derived from carbamoylcyanonitrosomethanide (ccnm)

Abstract

A mixed-valence octanuclear manganese complex of formula [MnII4MnIII4O4(ccnm)12]·4MeCN·7H2O (1·4MeCN·7H2O) (ccnm = carbamoylcyanonitrosomethanide) has been synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and magnetic measurements. The metal core of 1 adopts a tetra-capped (with MnII ions) distorted [MnIII4O4]4+ cubane topology, with a three-J magnetic analysis indicating that the cluster displays dominant antiferromagnetic interactions. Three equally possible fits were obtained, all leading to a spin ground state of S = 0 with S = 1, 2 and 3 close in energy. Comparisons of the magnetic analysis are made with that published for a related Mn8 cluster and, more generally, with other MnIIIMnIII and MnIIIMnII fragments in clusters of various types. Show more