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 T_N≈ 12 K.