The direct synthesis of organocalcium compounds (heavy Grignard reagents) by the reduction of organyl halides with activated calcium powder succeeded in a straightforward manner for organic bromides and iodides that are bound at sp -hybridized carbon atoms. Extension of this strategy to alkyl halides was very limited, and only the reduction of trialkylsilylmethyl bromides and iodides with activated calcium allowed the isolation of the corresponding heavy Grignard reagents. Substitution of only one hydrogen atom of the methylene moiety by a phenyl or methyl group directed this reduction toward the Wurtz-type coupling and the formation of calcium halide and the corresponding C-C coupling product. The stability of the methylcalcium and benzylcalcium derivatives in ethereal solvents suggests an unexpected reaction behavior of the intermediate organyl halide radical anions. Quantum chemical calculations verify a dependency between the ease of preparative access to organocalcium complexes and the C-I bond lengths of the organyl iodides. The bulkiness of the trialkylsilyl group is of minor importance. Chloromethyltrimethylsilane did not react with activated calcium; however, halogen-exchange reactions allowed the isolation of [Ca(CH SiMe )(thf) (μ-Cl)] . Furthermore, the metathetical approach of reacting [Ca(CH SiMe )I(thf) ] with KN(SiMe ) and the addition of N,N,N',N'',N''-pentamethyldiethylenetriamine (pmdeta) allowed the isolation of heteroleptic [CaCH SiMe {N(SiMe ) }(pmdeta)]. In the reaction of this derivative with phenylsilane, the trimethylsilylmethyl group proved to be more reactive than the bis(trimethylsilyl)amido substituent.

Heteroleptic phenylacetylide complexes [{F 12 -Tp 4Bo,3Ph }Ae(CCPh)] x of calcium (Ae = Ca, x = 2; 2) and magnesium (Ae = Mg, x = 1; 4) containing the highly fluorinated 3-phenyl hydrotris(indazolyl)borate {F 12 -Tp 4Bo,3Ph } − ligand have been synthesized by acid−base reactions between the corresponding silylamido derivatives [{F 12 -Tp 4Bo,3Ph }Ae{N(SiRMe 2 ) 2 }] (R = Me, Ae = Ca (1); R = H, Ae = Mg (3)) and PhCCH. Compounds 2 and 4 have been characterized by NMR spectroscopy and X-ray diffraction analysis. 2 crystallizes as a dinuclear complex, showing two nonsymmetrical "side-on" (π-type) interactions between the acetylide units and the Ca centers, whereas 4 crystallizes as a mononuclear complex, displaying a four-coordinate magnesium. The molecular structure of the complex [{F 12 -Tp 4Bo,3Ph }Mg-{N(SiMe 2 H) 2 }] (3), obtained by the salt metathesis reaction between [Mg{N(SiMe 2 H) 2 } 2 ] and [Tl{F 12 -Tp 4Bo,3Ph }], is also reported. 3 is also four-coordinate and exhibits a Mg•••β-Si−H agostic distortion. The synthesis and in situ characterization of the heteroleptic alkyl complex [{F 12 -Tp 4Bo,3Ph }Ca{CH(SiMe 3 ) 2 }(THF)] ( 5) is also reported, although attempts to isolate this compound failed due to its extreme sensitivity to temperature.