Dimethylcalcium.

The salt metathesis reaction between homoleptic calcium bis(trimethylsilyl)amide [Ca{N(SiMe)}] and "halide-free" methyllithium allowed for the isolation of X-ray-amorphous dimethylcalcium [CaMe] in good yields and purities. The formation of [CaMe] was proven by microanalysis and NMR/FTIR spectroscopic methods as well as a series of derivatization reactions. Despite slowly decomposing thf, [CaMe] could be crystallized from chilled thf solutions as the heptametallic adduct [(thf)CaMe]. Reaction of [CaMe] with CaI in thf led to the dimeric complex [(thf)Ca(Me)(I)], whereas in tetrahydropyran (thp) the trinuclear complex [(thp)Ca(Me)(I)] was obtained, both representing the first crystallographically characterized heavy-Grignard compounds with methyl groups as the hydrocarbyl ligand. While protonolysis of [CaMe] with the superbulky proligand HTp in nonpolar solvents gave homoleptic (Tp)Ca, reaction in donor solvents (thf, thp) afforded the monomeric complexes [(Tp)Ca(Me)(thf)] and [(Tp)Ca(Me)(thp)], which are the first examples bearing terminal Ca-CH functionalities. Grignard-type nucleophilic methyl-group transfer to hexamethylacetone gave access to the dimeric alkoxide complexes [(thf)Ca(OCtBuMe)] and [(tBuCO)Ca(μ-OCtBuMe)Ca(OCtBuMe)]. Finally, addition of the Lewis acid GaMe to [CaMe] led to the corresponding tetramethylgallate compound [Ca(GaMe)].