Reactions of the phenyl-substituted five-membered titanacyclocumulene - Unusual coupling of a 1,4-disubstituted 1,3-butadiyne with two titanium atoms

Article abstract of DOI:10.1016/S0022-328X(96)06694-6

The reaction of Cp₂Ti(η²-Me₃SiC₂SiMe₃) with equimolar amounts of PhC≡C-C≡CPh gives the unstable five-membered titanacyclocumulene 1, which is stabilized by dimerization to yield the dinuclear complex 2. In this reaction complex 1 shows an equilibrium and also behaves as a metallacyclocumulene and a metal alkyne complex. By the coupling of the internal double bond of the cyclocumulene with a complexed triple bond of the diyne, a complex with fused titanacyclopentadiene and titanacyclopentene is formed. With acetone and water complex 1 reacts like an alkyne complex to give the titanadihydrofuran 4 and the titanoxane 5. Complex 2 was investigated by an X-ray structural determination.