Synthesis of double and quadruple butterfly Fe/E cluster complexes via a new type of selenium-centered anions (μ-RE)(μ-Se-)[Fe2(CO)6]2(μ4-Se) (E = S, Se, Te) derived from novel reaction of [μ-RE)(μ-CO)[Fe2(CO)6]- with (μ-Se2)Fe2(CO)6.: Crystal structures of (μ4-Se-containing double clusters (μ-EtS)(μ-PhCH2Se) [Fe2(CO)6]2(μ4-Se), (μ-p-MeC6H4Se)(μ-MeSe) [Fe2(CO)6]2(μ4-Se) and (μ-p-MeC6H4Te)(μ-MeSe) [Fe2(CO)6]2(μ4-Se)

The [Et3NH](+) or [MgBr](+) salts of anions [(mu -RE)(mu -CO)Fe-2(CO)(6)](-) (1, E = S, Se, Te) reacted with (mu -Se-2)Fe-2(CO)(6) followed by treatment of the [Et3NH](+) or [MgBr](+) salts of the intermediate selenium-centered anions (mu -RE)(u-Se-) [Fe-2(CO)(6)](2)(mu (4)-Se) (3) with monohalide PhCH2Br or MeI to give a series of double butterfly Fe/E cluster complexes (mu -RE)(mu -(RSe)-Se-1)-[Fe-2(CO)(6)](2)(mu (4)-Se) (4, RE = EtS, R-1 = PhCH2; 5, t-BuS, PhCH2; 6, p-MeC6H4Se, PhCH2; 7, p-MeC6H4Se, Me; 8, p-MeC6H4Te, PhCH2; 9, p-MeC6H4Te, Me). Similarly, reaction of the in situ prepared [Et3NH](+) salt of the intermediate selenium-centered anion (mu -t-BuS)(mu -Se-)[Fe-2(CO)(6)](2)(mu (4)-Se) with dihalide 1,2-(BrCH2)(2)C6H4 or 1,3-(BrCH2)(2)-5-MeC6H3 afforded quadruple butterfly Fe/E cluster {(mu -t-BuS)[Fe-2(CO)(6)](2)(mu (4)-Se)}(2)(mu -1-SeCH2C6H4CH2Se-2-mu) (10) or double butterfly Fe/E cluster (mu -t-BuS) [(mu -t-SeCH2-3-BrCH2-5-MeC6H3) [Fe-2(CO)(6)](2) (mu (4)-Se) (11) and quadruple butterfly Fe/E cluster {(mu -t-BuS) [Fe-2(CO)(6)](2)(mu (4)-Se)}(2)(mu -1-SeCH2-5-MeC6H3CH2Se-3-mu) (12), respectively. All the new products 4-11 have been characterized by elemental analysis, IR, H-1 and Se-77 NMR spectroscopy, and for 4, 7, and 9 single-crystal X-ray diffraction techniques.