Organometallic selenolates .7. (benzylselenolato-Se)tricarbonyl(eta(5)-cyclopentadienyl)molybdenum(II) and bis[1,2(eta(5))-cyclopentadienyl]-di-mu-ethylselenolato-di-mu-selenido-dimolybdenum(IV) (Mo-Mo)

Compound (1), [Mo(eta(5)-C5H5)(C7H7Se)(CO)(3)], is monomeric in the solid state. The Cp(CO)(3)MoSe moiety (where Cp is cyclopentadienyl) displays a 'piano-stool' arrangement with an Mo-Se bond length of 2.6294(4)Angstrom and an essentially ideal tetrahedral bond angle at selenium [109.74(8)degrees]. The binuclear compound (2), [Mo-2(eta(5)-C5H5)2(C2H5Se)(2)(Se)(2)], consists of linear Cp-Mo-Mo-Cp moieties with Mo=Mo double bonds, which are quadruply bridged by two pairs of selenido and ethylselenolato ligands.