Reinvestigation of the synthesis of phenylcalcium iodide and the first structural characterization of a heavy Grignard reagent as [((thf)2CaPhI)3 · (thf)CaO] with a central Ca4 tetrahedron

Phenylcalcium iodide is accessible by direct synthesis from activated calcium and iodobenzene in THF at low temperatures. The use of chloro- or bromobenzene as well as of another solvent such as diethylether lowers the yield significantly. Phenylcalcium iodide cleaves THF already at −20 °C under formation of benzene. From this reaction solution single crystals of the title compound precipitate. The central structural fragment consists of a distorted calcium tetrahedron, centered by an oxygen atom and with Ca atoms being bridged by phenyl groups (average Ca–C 257 pm) and iodide ligands.