Synthesis, structure and formation pathways of new Fe–S complexes containing [Fe 2S 2]-units in different valences, [Fe 2S 2(CO) 4(PPh 3) 2], [Fe 3S 2(CO) 6(PPh 3) 3] and [Fe 4S 2(CO) 10] 2− and the origin of the [Fe 2S 2]-unit in metal–[Fe 2S 2(CO) 6] complexes

Abstract

Novel Fe–S cluster complexes, [Fe 2S 2(CO) 4(PPh 3) 2] ( 1), [Fe 3S 2(CO) 6(PPh 3) 3] ( 2) and [Ph 4P] 2[Fe 4S 2(CO) 10] ( 3) have been synthesized by the reaction of LiEt 3BH with [Fe 2S 2(CO) 6] in the presence of CuCl–PPh 3, AgNO 3–PPh 3 and CuClO 3–MeCN, respectively.Structure determination indicated that 1, 2 and 3, respectively, possessed [Fe 2S 2] 0 core with [Fe 2S 2] 0-unit, [Fe 3S 2] 0 with [Fe 2S 2] 2− and [Fe 4S 2] 2− core with [Fe 2S 2] 4− unit, which implied that [Fe 2S 2(CO) 6] 2−, as a starting material, underwent a disproportionation in the synthetic reaction.Investigating the structure and synthetic reaction, an origin of the different valence[Fe 2S 2]-units and formation pathways of those clusters via disproportionation of the [Fe 2S 2(CO) 6] 2− following by ‘Unit Construction‘ were proposed and discussed.