NEUTRAL AND CATIONIC IRON-SULFUR COMPLEXES AND CLUSTERS SYNTHESES AND CRYSTAL-STRUCTURES OF [FE(SR)2L2].PHME AND [FE4S4(SR)2L2], AND ON THE FORMATION OF [FE(SR)L3]+, [FEL4]2+, [FE4S4(SR)L3]+ AND [FE4S4L4]2+ (R = 2,4,6-I-PR3C6H2 - L = SC(NME2)2)

The reaction of [FeI2L2] (1; L = SC(NMe2)2) with KSR (R = 2,4,6-i-Pr3C6H2) yields [Fe(SR)2L2].PhMe (2). Oxidation of the thiolate ligands of 2 with ((Me2N)2CSSC(NMe2)2)2+ affords the cationic complexes [Fe(SR)L3]+ and [FeL4]2+, which were isolated as tetraphenylborate salts. A mixed ligand neutral iron sulfur cluster [Fe4S4(SR)2L2] (3) has been synthesized by the reaction of 2 with elemental sulfur. 3 is a precursor for cationic clusters which are obtained via the above-mentioned oxidation. The structures of 2 and 3 were determined from single crystal X-ray diffraction data. 2 crystallizes in the monoclinic space group C2/c with a = 1807.8(1), b = 1000.6(1), c = 2946.0(2) pm, beta = 101.16(1)-degrees, V = 5227.6 x 10(6) pm3, Z = 4, R = 0.067. The complex exhibits C2-symmetry and a distorted tetrahedral coordination of Fe(II) (S-Fe-S angles between 101.7 and 125.7-degrees). The Fe-S(thiourea) and Fe-S(thiolate) bond lengths were found to be 240.3(2) and 231.5(1) pm, respectively. 3: triclinic, P1, a = 1020.2(2), b = 1035.3(2), c = 1402.1(2) pm, alpha = 73.50(1), beta = 70.47(1), gamma = 84.38(1)-degrees, V = 1338.2 x 10(6) pm3, Z = 1, R = 0.039. 3 shows a slightly compressed Fe4S4 core structure. The Fe-Fe distances range from 269.1 to 278.1 pm. The shortest and longest distances are observed between those Fe atoms which have two thiourea and two thiolate ligands, respectively.