The synthesis, and properties of Fe/Mo/S clusters with MoFe3S4 cubane subunits, Mo bound bidentate oxalate ligands and terminal or bridging cyanide ligands. Structural characterization of (Et4N)3[(C2O4)(CN)MoFe3S4Cl3] and (Et4N)5{[C2O4)MoFe3S4Cl2]2([mu]-CN)([mu]-S)}

Abstract

The reaction of (Et4N)3[(C2O4)MoFe3S4Cl4] (I) with (Et4N)CN affords [(C2O4)(CN)MoFe3S4Cl3]3- (IV) in nearly quantitative yields. The reaction of I with 0.5 eq. of (Et4N)CN and 0.5 eq. of a source of S2- affords the doubly-bridged double-cubane {[(C2O4)MoFe3S4Cl2]2([mu]2-CN)([mu]2-S)}5- (V) in [approximate]30% yield. Single crystal X-ray structures were determined for IV and V. The mean Fe---Fe, Fe---S and Fe---Cl bond distances in IV at 2.713(3), 2.270(5) and 2.214(5) A, are typical for MoFe3S4 cubane-like structures. The Mo---C(N) and C---N bond lengths are found at 2.19(2) and 1.04(2) A, respectively. The pentaanion in V consists of two doubly-bridged cubane subunits bridged by [mu]2-CN- ligand through the Mo atoms and a [mu]s-S2- through two Fe atoms. The Mo...Mo and Fe...Fe(intercube) distances and the Fe---[mu]2-S---Fe angle are found at 5.267(4), 3.443(7) and 104.1(4)[deg]. The spectroscopic and electrochemical features of IV and V are discussed.