Silver(I) acetylides stabilized by η2-alkynes: Synthesis, reaction chemistry and solid state structures

Individual synthetic routes to heterobimetallic Ti(IV)–Ag(I) acetylides of type {[Ti](μ-σ,π-CCR1)2}AgCCR2 ([Ti] = (η5-C5H4SiMe3)2Ti: R1 = SiMe3: 6, R2 = SiMe3; 7, R2 = Ph. R1 = tBu: 8, R2 = SiMe3; 9, R2 = Ph. [Ti] = (η5-C5H5)2Ti): 10, R1 = tBu, R2 = SiMe3) including (i) the reaction of {[Ti](μ-σ, π-CCR1)2}AgNO3 ([Ti] = (η5-C5H4SiMe3)2Ti): 1, R1 = SiMe3; 2, R1 = tBu. [Ti] = (η5-C5H5)2Ti: 3, R1 = tBu) with LiCCR2 (4, R2 = SiMe3; 5, R2 = Ph) and (ii) treatment of [Ti](CCSiMe3)2 ([Ti] = (η5-C5H4SiMe3)2Ti) (11) with [AgCCR2] (12, R2 = SiMe3; 13, R2 = 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(CCR2)2)Li(OEt2)]n (14) and [Ti](CCR1)2. Coordination polymer 14 is also accessible, when, for example, [AgCCSiMe3] (12) is treated with 1 eq. of LiCCSiMe3 (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 R2CC–CCR2 together with [Ti](CCR1)2 and elemental silver.Complexes 6–10 contain a mono-nuclear AgCCR2 entity stabilized by the chelate-bonded organometallic π-tweezer molecule [Ti](CCSiMe3)2, which was evinced by structure determination of 7 in the solid state. In 14 linear [Me3SiCC–Ag–CCSiMe3]− units are connected by [Li(OEt2)]+ building blocks forming a coordination polymer.

The synthesis and properties of {[Ti](μ-σ, π-CCR1)2}AgCCR2 ([Ti] = (η5-C5H4SiMe3)2Ti, (η5-C5H5)2Ti; R1 = SiMe3, tBu, R2 = SiMe3, Ph) as well as its reaction behavior towards LiCCR2 is described. The structures of {[Ti](μ-σ,π-CCSiMe3)2}AgCCPh and [Ag((CCSiMe3)2)Li(OEt2)]n in the solid state are reported.Figure optionsDownload as PowerPoint slideHighlights
► Organometallic π-tweezer chemistry for stabilizing low-valent transition metal species.
► Stabilization of mono-nuclear silver(I) acetylides by the chelating effect of a organometallic 1,4 diyne.
► Synthesis of heterobimetallic early-late Ti–Ag transition metal complexes.
► Formation of a coordination polymer based on silver(I) acetylides and [Li(OEt2)] units.