Reactions of methyl-substituted titanocene-bis(trimethylsiiyl)acetylene complexes with acetone azine: crystal structures of (eta(5):eta(1)-C5HMe3CH2CMe2NH)(2)Ti and (C5Me5)(2)Ti(N=CMe2)

The titanofene-bis(trimethylsilyl)acetylene (BTMSA) complexes Cp'Ti-2[eta(2 )-C-2(SiMe3)(2)] (Cp'=C5H5-nMen; n = 0-5) react with acetone azine Me2C-N-N -CMe2 (AA) in two different ways depending on the number of Me substituents at the Cp' ligands (n). For n = 0-2, BTMSA is replaced by AA, which then u ndergoes an oxidative addition accompanied by a proton transfer, affording titana-2-isopropyl-4-methyl-2,3-diazacyclopent-3-ene complexes A0-A2. For n = 3-5, replacement of the acetylene is followed by the splitting of AA to give either (C5Me5)(2)Ti(III)(N=CMe2) (C5) or the Ti(IV) (Cp'A)(2)Ti comple xes B3 and B4 for rr = 3 and 4, respectively. The intramolecularly bridging Cp'A ligand 1-(eta(5)-2,3,5-trimethylcyclopentadienide)-2-(eta(1)-amide)-2 ,2'-dimethylethane arises from a formal insertion of the C=N bond of isopro pylidene amide into a C-IS bond of one methyl group of the cyclopentadienyl ligands before or after splitting of AA. Crystal structures of C5 and (eta (5):eta(1)-C5HMe3CH2CMe2NH)(2)Ti(IV) (B4) were determined. (C) 2000 Elsevie r Science S.A. All rights reserved.