Diyne-bridged metal clusters: Synthesis and spectroscopic characterization of [(CO)(6)Fe2Se2{mu-HC=C(CCR)}M] (R=Me and Bu-n; M=Cp2Mo2(CO)4, Co-2(CO)(6), Ru-3(CO)(10) and Os-3(CO)(10)). Structural characterization of [(CO)(6)Fe2Se2{mu-HC=C((CCBu)-Bu-n)}Cp2Mo2(CO)(4)] and [(CO)(6)Fe2Se{mu-HC=C(CCMe)}Ru-3(CO)(10)]

Room temperature reaction of [(CO)(6)Fe-2{mu-SeC(H)=C(C=CR)Se}], with the dimetallic species, Cp2Mo2(CO)(4) and Co-2(CO)(8), afforded the adducts [(CO)(6)Fe2Se2(mu-HC=C(CCR)}Cp2Mo2(CO)(4)] (R = Me, 1; R = Bu-n, 2) and [(CO)(6)Fe2Se2{mu-HC=C(CCR))Co-2(CO)(6)] (R=Me, 3; R=Bu-n, 4) respectively. On reaction of Ru-3(CO)(10) (NCMe)(2) with [(CO)(6)Fe-2{mu-SeC(H)=C(C=CR)Se}], the new diyne-bridged mixed-metal clusters [(CO)(6)Fe2Se2{mu-HC=C(CCR)}Ru-3(CO)(10)] (R = Me, 5; R = Bu-n, 6) were obtained. Similarly, [(CO)(6)Fe2Se2{mu-HC=C((CCBu)-Bu-n)}Os-3(CO)(10)], 7, was isolated from the reaction of [(CO)(6)Fe-2{mu-SeC(H)=C(C=(CBu)-Bu-n)Se}] with Os-3(CO)(10)(NCMe)(2). Compounds 1-7 were characterized by IR and H-1, C-13 and Se-77 NMR spectroscopy. The structures of 2 and 5 were established by single crystal X-ray diffraction study. Both contain an Fe2Se2 butterfly core bridged by an HCC unit of the diyne HC=CC=CR across the two Se atoms. In 2, the substituted acetylenic moiety is transversely bridged to the Mo-Mo bond and in 5, it forms a mu(3)-//-eta(2) bridge to an Ru, triangular core