SYNTHESES AND STRUCTURES OF MIXED-LIGAND TETRAIRON-SULFUR CLUSTERS, [CP'(2)(PH(2)C(2)S(2))(2)FE4S4](PF6) AND [CP'(3)(PH(2)C(2)S(2))FE4S5](PF6)(N) (N=1 AND 2) (CP'=ETA(5)-C(5)ME(5)) - STRUCTURAL-CHANGE OF THE CLUSTERS ACCOMPANYING ELECTRON-TRANSFER REACTIONS

The cycle voltammogram (CV) of the mixed-ligand cubane-type cluster Cp '(2)(Ph(2)C(2)S(2))(2)Fe4S4 (4) exhibits four reversible one-electron redox waves, corresponding to +2/+1, +1/0, 0/-1, and -1/-2 charged clu ster couples. The CV of the mixed-ligand cubane-like cluster Cp'(3)(Ph (2)C(2)S(2))Fe4S5 (5) exhibits four reversible one-electron redox wave s, corresponding to +3/+S, +2/+1, 1/0, and 0/-1 charged cluster couple s. Oxidized clusters, [4](PF6) CH2Cl2, [5](PF6) 2Me(2)CO and [5](PF6)2 Me(2)CO, were synthesized by chemical and/or electrochemical methods. The structures of these three salts were determined by X-ray crystall ography and compared with those of the parent clusters 4 and 5. Both d usters 4 and 5 shrink as they are oxidized, indicating that the electr ons are removed from antibonding orbitals. The crystallographic data a re as follows: [4](PF6) CH2Cl2: orthorhombic, Pna2(1) with a = 17.259( 3), b = 25.682(4), c = 12.628(2) Angstrom, V = 5597(2) Angstrom(3), Z = 4 and R = 0.066; [5](PF6) 2Me(2)CO: triclinic, P $($) over bar$$ 1 w ith a = 14.112(4), b = 17.712(3), c = 13.325(4) Angstrom, alpha = 108. 08(2), beta = 114.74(3), gamma = 84.00(1)degrees, V = 2874(1) Angstrom (3), Z = 2 and R = 0.066; [5](PF6)(2) Me(2)CO: triclinic, P $($) over bar$$ 1 with a = 14.985(1), b = 15.540(1), c = 12.951(1) Angstrom, alp ha = 93.40(2), beta = 95.04(1),gamma = 96.76(1)degrees, V = 2976(1) An gstrom(3), Z = 2 and R = 0.056.