REACTIONS OF THE PHENYL-SUBSTITUTED 5-MEMBERED TITANACYCLOCUMULENE - UNUSUAL COUPLING OF A 1,4-DISUBSTITUTED 1,3-BUTADIYNE WITH 2 TITANIUM ATOMS

The reaction of Cp2Ti(eta(2)-Me3SiC2SiMe3) with equimolar amounts of P hC=C-C=CPh gives the unstable five-membered titanacyclocumulene 1, whi ch is stabilized by dimerization to yield the dinuclear complex 2. In this reaction complex 1 shows an equilibrium and also behaves as a met allacyclocumulene and a metal alkyne complex. By the coupling of the i nternal double bond of the cyclocumulene with a complexed triple bond of the diyne, a complex with fused titanacyclopentadiene and titanacyc lopentene is formed. With acetone and water complex 1 reacts like an a lkyne complex to give the titanadihydrofuran 4 and the titanoxane 5. C omplex 2 was investigated by an X-ray structural determination. (C) 19 97 Published by Elsevier Science S.A.