Dimethylcalcium

The salt metathesis reaction between homoleptic calcium bis­(trimethylsilyl)­amide [Ca­{N­(SiMe3)2}2]2 and “halide-free” methyl­lithium allowed for the isolation of X-ray-amorphous dimethyl­calcium [CaMe2]n in good yields and purities. The formation of [CaMe2]n was proven by micro­analysis and NMR/FTIR spectroscopic methods as well as a series of derivatization reactions. Despite slowly decomposing thf, [CaMe2]n could be crystallized from chilled thf solutions as the hepta­metallic adduct [(thf)10­Ca7Me14]. Reaction of [CaMe2]n with CaI2 in thf led to the dimeric complex [(thf)3Ca­(Me)­(I)]2, whereas in tetrahydropyran (thp) the trinuclear complex [(thp)5Ca3­(Me)5(I)] was obtained, both representing the first crystallographically characterized heavy-Grignard compounds with methyl groups as the hydro­carbyl ligand. While protonolysis of [CaMe2]n with the superbulky proligand HTptBu,Me in nonpolar solvents gave homoleptic (TptBu,Me)2Ca, reaction in donor solvents (thf, thp) afforded the monomeric complexes [(TptBu,Me)­Ca­(Me)­(thf)] and [(TptBu,Me)­Ca­(Me)­(thp)], which are the first examples bearing terminal Ca–CH3 functionalities. Grignard-type nucleophilic methyl-group transfer to hexamethyl­acetone gave access to the dimeric alkoxide complexes [(thf)­Ca­(OCtBu2Me)2]2 and [(tBu2CO)­Ca­(μ2-OCtBu2Me)3­Ca­(OCtBu2Me)]. Finally, addition of the Lewis acid GaMe3 to [CaMe2]n led to the corresponding tetramethyl­gallate compound [Ca­(GaMe4)2]n.均配型双(三甲基硅基)氨基钙[Ca{N(SiMe3)2}2]2与"无卤"甲基锂之间的复分解反应，可高产率、高纯度分离得到X射线无定形的二甲基钙聚合物[CaMe2]n。通过元素微量分析、核磁共振（nuclear magnetic resonance, NMR）/傅里叶变换红外光谱（Fourier-transform infrared spectroscopy, FTIR）法以及一系列衍生化反应，证实了[CaMe2]n的生成。尽管[CaMe2]n会缓慢降解四氢呋喃（tetrahydrofuran, thf），但仍可从低温冷却的thf溶液中结晶得到七金属加合物[(thf)10Ca7Me14]。[CaMe2]n与碘化钙（CaI2）在thf中反应，得到二聚体配合物[(thf)3Ca(Me)(I)]2；而在四氢吡喃（tetrahydropyran, thp）中则得到三核配合物[(thp)5Ca3(Me)5(I)]，二者均为首例经晶体学表征的、以甲基作为烃基配体的重格氏试剂。将[CaMe2]n与超大位阻质子配体HTptBu,Me在非极性溶剂中进行质子解反应，可得到均配型配合物(TptBu,Me)2Ca；而在给体溶剂（thf、thp）中反应则生成单核配合物[(TptBu,Me)Ca(Me)(thf)]和[(TptBu,Me)Ca(Me)(thp)]，这是首例带有末端Ca–CH3官能团的配合物。格氏型亲核甲基转移反应与六甲基丙酮反应，可得到二聚体烷氧基配合物[(thf)Ca(OCtBu2Me)2]2以及[(tBu2CO)Ca(μ2-OCtBu2Me)3Ca(OCtBu2Me)]。最后，向[CaMe2]n中加入路易斯酸（Lewis acid）三甲基镓（GaMe3），可得到相应的四甲基镓酸盐聚合物[Ca(GaMe4)2]n。