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[摘要]：A family of novel titanasiloxanes contg. the structural unit {[Ti(h5-C5Me5)O]3} were synthesized by hydron-transfer processes involving reactions with equimol. amts. of m3-alkylidyne derivs. [{Ti(h5-C5Me5)(m-O)}3(m3-CR)] (R = H (1), Me (2)) and monosilanols, R3'Si(OH), silanediols, R2'Si(OH)2, and the silanetriol tBuSi(OH)3. Treatment of 1 and 2 with triorganosilanols (R' = Ph, iPr) in hexane affords the new metallasiloxane derivs. [{Ti(h5-C5Me5)(m-O)}3(m-CHR)(OSiR3')] (R = H, R' = Ph (3), iPr (4); R = Me, R' = Ph (5), iPr (6)). Analogous reactions with silanediols, (R' = Ph, iPr), give the cyclic titanasiloxanes [{Ti(h5-C5Me5)(m-O)}3(m-O2SiR'2)(R)] (R = Me, R' = Ph (7), iPr (8): R = Et, R' = Ph (9), iPr (10)). Use of tBuSi(OH)3 with 1 or 2 at room temp. produces the intermediate complexes [{Ti(h5-C5Me5)(m-O)}3(m-O2Si(OH)tBu)(R)] (R = Me (11), Et (12)). Further heating of solns. of 11 or 12 affords the same compd. and methane or ethane elimination, resp. The x-ray crystal structures of 3, 4, 6, 8, 10, 12, and 13 were detd. To gain an insight into the mechanism of these reactions, DFT calcns. were performed on the incorporation of monosilanol to the model complex [{Ti(h5-C5H5)(m-O)}3(m3-CMe)] (2H). The propose mechanism consists of three steps: (1) hydron transfer from the silanol to one of the O atoms of the Ti3O3 ring, forming a titanasiloxane; (2) intramol. hydron migration to the alkylidyne moiety; and (3) a m-alkylidene ligand rotation to give the final product. |
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