Reactions of titanocene-bis(trimethylsilyl)ethyne complexes with diethynylsilane derivatives

Titanocene complexes [Ti(eta (5)-C5H5-nMen)(2)(eta (2)-Me3SiC=CSiMe3)] (n = 0, 4 and 5) react uniformly with siladiynes (R2SI)-S-2(C=CR1)(2),, where R -1 = Ph, and R-2 = Ph or Me, at elevated temperature in hydrocarbon solvent s to give the corresponding silacyclobutene-annelated titanacyclobutene com plexes, 3-bis(eta (5)-cyclopentadienyl)titana-6-diorganylsilabicyclo[2.2.0] hexa-1(2),4(5)-dienes, [(eta (5)-C5H5-nMen)(2)Ti{(R2C4)-C-1(SiR22)}]. Produ cts arising from [Ti(eta (5)-C5H5-nMen)(2)(eta (2)-Me3SiC=CSiMe3)] (n = 0, 2 (1,3-isomer), 4 and 5) and Me2Si(C=CCMe3)(2) vary with n: the non-methyla ted titanocene complex affords a mixture of an analogous silacyclobutene-an nelated titanacyclobutene and [{Ti(eta (5)-C5H5)(2)}(2){mu-eta (3-5):eta (4 -6)-Me3CC=CC=CCMe3}], the permethylated titanocene precursor gives mainly t he allyldiene complex [Ti(eta (5)-C5Me5)(eta (3):eta (4)-C5Me3(CH2)(2))] wh ile no titanium-containing product could be isolated for n = 4. The reactio n of [Ti(eta (5)-1,3-C5H3Me2)(2)(eta (2)-Me3SiC=CSiMe3)] with Me2Si(C=CCMe3 )(2), however, cleanly affords the expected silacyclobutene-titanacyclobute ne complex. All complexes were studied by spectral methods and solid-state structure of two representatives, [(eta (5)-C5Me5)(2)Ti{Ph2C4(SiMe2)}] and [(eta (5)-1,3-C5H3Me2)(2)Ti{(Me3C)(2)C-4(SiMe2)}] was determined by single- crystal X-ray diffraction. (C) 2001 Elsevier Science B.V. All rights reserv ed.