ALKYNE-NIOBIUM(I) COMPLEXES WITH FUNCTIONALIZED ALKYNES - SYNTHESIS, STRUCTURE AND REACTIVITY

The reaction between INb(CO)(3)(PR(3))(3) and diynes yielded the compl exes all-trans-[INb(CO)(2)(PR(3))(2)diyne] (PR(3) = PEt(3); diyne = 2, 4-hexadiyne (la), 1,5-hexadiyne(1b). PR(3) = PMe(2)Ph, diyne = 2,6-oct adiyne (Ic)). Only one of the acetylenic bonds coordinates. Reaction o f INb(CO)(3)(PMe(2)Ph)(3) with Ph(2)PC = CPPh(2) generated INb(CO)(2)( PMe(2)Ph)(2)(Ph(2)PC = CPPh(2)) (2), again with the ligands mutually t rans. The W-induced reaction between 2 and W(CO)(6) led to fac-[W(CO)( 3)(PMe(2)Ph)(3)] (3). la, 2 and 3 were characterized by X-ray structur e analyses.