Trinuclear and tetranuclear manganese clusters derived from cyano(imino(methoxy)methyl)nitrosomethanide (cmnm)

Abstract

Three manganese clusters have been synthesised via the reaction of MnII with cyano(imino(methoxy)methyl)nitrosomethanide (cmnm), obtained from the in situ nucleophilic addition of MeOH to dicyanonitrosomethanide (dcnm). X-ray crystallographic studies show that the complex [MnII3(cmnm)6]·MeOH (1) is a linear trinuclear species, with a central octahedral and two outer trigonal-prismatic manganese(II) ions. Two mixed-valent tetranuclear complexes [MnII2MnIII2O2(cmnm)4Cl2(MeOH)6] (2) and [MnII2MnIII2O2(cmnm)4Cl2(MeOH)4(pzH)2]·2MeOH (3) (pzH=pyrazole) contain two MnII and two MnIII ions in butterfly-type structures, with the six-coordinate ‘body’ MnIII ions bridged to the seven-coordinate ‘wingtip’ MnII ions by μ3-O2− and by nitroso oxygen atoms of the cmnm ligands. The formation of the trinuclear and tetranuclear manganese clusters is dependent on the stoichiometry used in the reactions. Solid state DC magnetic susceptibility studies on complexes 1 and 3 reveal that antiferromagnetic interactions are dominant within the clusters. Fits of the data reveal an S=5/2 ground state for 1 and a S=0 ground state for 3, with several close lying excited states found in both cases.