[Fe4S4l2+-Cluster mit Thioharnstoffliganden: [FeIL3][Fe4S4I3L]' (L = (Me2N)2CS) und [Fe4S4I2L'2](L' = (C4H9NH)2CS)

Abstract

(1) The mixed terminal ligand iron-sulfur clusters [F eIL 3][Fe4S4I3L] and [Fe4S4I2L '2] (2) with the neutral ligands L = (M e2N )2CS and L' = (C4H 9N H )2CS have been synthesized by the reaction o f F eI2L2 with 1.5 equivalents o f Fe(C O )5 and 2 equivalents o f sulfur and by the reaction o f F eI2L '2 with 3 equivalents o f Fe(CO)^ and 4 equivalents o f sulfur, respectively. The crystal structures o f 1 and 2 were determined from single crystal X -ray diffraction data. 1 crystallizes in the triclinic space group P 1 with a = 968.6( 1), b = 1466.2( 1), c = 1679.1(1) pm, a = 91.51(1),/?= 93.43( 1), y = 90.82( 1)°, V = 2379.2 * 106 pm 5, Z = 2, R = 0.054. 2 crystallizes in the m onoclinic space group P2 Jn with a = 930.2(1), b = 1666.1(1), c = 2335.6(1) pm, β = 97.26°, V = 3 5 90.8 x 106 pm 3, Z = 4. R = 0.055. The anion [Fe4S4I3L] o f 1 exhibits a nearly undistorted [Fe4S4]2+ core. The F e - S distance to the thiourea ligand is found at 230.6 pm. The m ost striking feature o f the neutral cluster o f 2 is the very short F e - F e distance (268.7 pm) between the iron atom s with thiourea ligation which is possibly a consequence of back-donation. The F e - S thiourea distances in 2 were found to be 230.8 and 231.5 pm , respectively.