Silver(I) acetylides stabilized by η~2-alkynes: Synthesis, reaction chemistry and solid state structures

摘要

Individual synthetic routes to heterobimetallic Ti(IV)-Ag(I) acetylides of type {[Ti](μ-σ,π-CCR~1)_2}AgCCR~2 ([Ti] = (η~5-C_5H_4SiMe_3) _2Ti: R~1 = SiMe_3: 6, R~2 = SiMe _3; 7, R~2 = Ph. R~1 = ~tBu: 8, R ~2 = SiMe_3; 9, R~2 = Ph. [Ti] = (η~5-C_5H_5)_2Ti): 10, R~1 = ~tBu, R~2 = SiMe_3) including (i) the reaction of {[Ti](μ-σ, π-CCR~1)_2}AgNO_3 ([Ti] = (η~5-C_5H_4SiMe_3)_2Ti): 1, R~1 = SiMe_3; 2, R~1 = ~tBu. [Ti] = (η~5-C_5H_5)_2Ti: 3, R~1 = ~tBu) with LiCCR~2 (4, R~2 = SiMe_3; 5, R~2 = Ph) and (ii) treatment of [Ti](CCSiMe_3)_2 ([Ti] = (η~5-C_5H_4SiMe_3) _2Ti) (11) with [AgCCR~2] (12, R~2 = SiMe _3; 13, R~2 = Ph) are described. The reactions of 1-3 with 4 or 5 appeared to be sensitive towards stoichiometry because an excess of 4 or 5 resulted in the formation of [(Ag(CCR~2)_2)Li(OEt _2)]_n (14) and [Ti](CCR~1)_2. Coordination polymer 14 is also accessible, when, for example, [AgCCSiMe _3] (12) is treated with 1 eq. of LiCCSiMe_3 (4) in diethyl ether. The titanium(IV)-silver(I) acetylides 6-10 are stable in the dark and at low temperature, while on exposure to light and on heating they decompose to give R~2CC-CCR~2 together with [Ti](CCR~1) _2 and elemental silver. Complexes 6-10 contain a mono-nuclear AgCCR~2 entity stabilized by the chelate-bonded organometallic π-tweezer molecule [Ti](CCSiMe_3)_2, which was evinced by structure determination of 7 in the solid state. In 14 linear [Me _3SiCC-Ag-CCSiMe_3]~- units are connected by [Li(OEt_2)]~+ building blocks forming a coordination polymer.