Synthetic and Structural Investigations on Some New 1,2,4,5-(CH2)4C6H2 Moiety-Containing Butterfly Fe/S Cluster Complexes from Reactions of Tetrathiol 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12 or with Fe3(CO)12 in the Presence of Et3N

The 1,2,4,5-(CH2)4C6H2 moiety-containing butterfly Fe/S complexes [1,2-(CH2S2CH2)-4,5-(μ-SCH2)2C6H2]­[Fe2(CO)6] (1), [1,2,4,5-(μ-SCH2)4C6H2]­[Fe2(CO)6]2 (2), and [(1,2-Me2)-4,5-(μ-SCH2)2C6H2]­[Fe2(CO)6] (3) have been prepared by the reaction of tetrathiol 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12 under different conditions. Treatment of complex 1 with PPh3 or PMe3 in the presence of Me3NO or with the in situ generated N-heterocyclic carbene IMes (IMes = 1,3-bis­(mesityl)­imidazol-2-ylidene) afforded the corresponding monosubstituted single-butterfly complexes [1,2-(CH2S2CH2)-4,5-(μ-SCH2)2C6H2]­[Fe2(CO)5L] (4, L = PPh3; 5, L = PMe3; 6, L = IMes). However, in contrast to the above-mentioned reaction of tetrathiol 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12, the reactions of 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12 in the presence of Et3N, followed by treatment with PhCOCl or PhC­(Cl)NPh, resulted in formation of the quadruple- and triple-butterfly complexes [(μ-PhCO)­Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2] (7) and [(μ-PhCNPh)­Fe2(CO)6]2[Fe2(CO)6]­[1,2,4,5-(μ-SCH2)4C6H2] (8), whereas the same tetrathiol reaction system reacted with PhCCH to give quadruple- and triple-butterfly complexes [(μ-σ,π-PhCHCH)­Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2] (9) and [(μ-σ,π-PhCHCH)­Fe2(CO)6]2[Fe2(CO)6]­[1,2,4,5-(μ-SCH2)4C6H2] (10). More interestingly, the dithioformato ligand-containing quadruple-butterfly complex [(μ-SCSCH2Ph)­Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2] (11) could be prepared by the reaction of the tetrathiol system with CS2, followed by treatment with PhCH2Br, but the same tetrathiol/CS2 system reacted with CpFe­(CO)2I to afford the triple-butterfly complex [(μ-SCSFe­(CO)2Cp)­Fe2(CO)6]2[Fe2(CO)6]­[1,2,4,5-(μ-SCH2)4C6H2] (12). The possible pathways for production of complexes 1–3 and 7–12 are proposed, and the suggested intermediate [1,2-(HSCH2)2-4,5-(μ-SCH2)2C6H2]­[Fe2(CO)6] (M6) for formation of complex 1 has been successfully isolated under anaerobic conditions. The structures of complexes 1, 3, 4, 8, 9, and 11 have been confirmed by X-ray crystallography.