Charge-transfer salts formed from redox-active cubane cluster cations [M4(η-C5H4R)4(µ3-E)4]n+(M = Cr, Fe or Mo; E = S or Se) and various anions

Abstract

The synthesis and properties of the cluster salts [C]+[A]–{C = Mo4(η-C5H4Pri)4(µ3-S)4,* Mo4(η-C5H4Pri)4(µ3-Se)4, Fe4(η-C5H5)4(µ3-S)4,* Fe4(η-C5H4Me)4(µ3-S)4,* Cr4(η-C5H5)4(µ3-S)4, Cr4(η-C5H4Me)4(µ3-S)4, or Cr4(η-C5H4Me)4(µ3-Se)4; A = Fe4(NO)4(µ3-S)4} and [Mo4(η-C5H4Pri)4(µ3-S)4]2[Os6(CO)18]* are described along with the cluster salts of tetracyanoquinodimethane (tcnq) or tetracyanoethylene (tcne)[Mo4(η-C5H4Pri)4(µ3-S)4][tcnq],*[Fe4(η-C5H5)4(µ3-S)4][tcnq], [Fe4(η-C5H4Me)4(µ3-S)4][tcnq],*[Cr4(η-C5H5)4(µ3-S)4][(tcnq)2],[Cr4(η-C5H4Me)4(µ3-S)4][tcnq], [Cr4(η-C5H4Me)4(µ3-S)4][(tcnq)2], [Cr4(η-C5H4Me)4(µ3-Se)4][tcnq], [Cr4(η-C5H4Me)4(µ3-Se)4][(tcnq)2], [Mo4(η-C5H4Pri)4(µ3-Se)4][tcnq], [Mo4(η-C5H4Pri)4(µ3-Se)4][tcnq]3, and [Cr4(η-C5H4Me)4(µ3-S)4][tcne]. The cluster dithiolene salts [C]n+[Mo{S2C2(CF3)2}3]n–{C = Mo4(η-C5H4Pri)4(µ3-Se)4, Mo4(η-C5H4Pri)4(µ3-S)4, [Mo4(η-C5H4Pri)4(µ3-S)4]2, Cr4(η-C5H4Me)4(µ3-S)4, or Cr4(η-C5H4Me)4(µ3-Se)4} and [Mo4(η-C5H4Pri)4(µ3-S)4][Ni{S2C2(CN)2}2] are also reported. Crystal structures have been determined for the compounds marked* and also for the neutral selenium cubane [Mo4(η-C5H4Pri)4(µ3-Se)4]. The crystal structures of the cluster salts are not always those predicted from idealized ionic model considerations. Electrical conductivities and magnetic properties are described. The compound [Mo4(η-C5H4Pri)4(µ3-S)4][tcnq] has an unusual ribbon arrangement of the tcnq– anions and shows weak antiferromagnetic behaviour with TN≈ 12 K.