Synthesis and crystal structures of bis(diphenylphosphanyl)methanides of lithium and calcium as well as of their borane adducts.

The reaction of Li{HC(PPh(2))(2)}, which forms [(tmeda)(thf)Li{HC(PPh(2))(2)}] () in the presence of appropriate Lewis bases, with KOtBu and CaI(2) in THF yields [(thf)(3)Ca{CH(PPh(2))(2)}(2)] (). In complexes and the bis(diphenylphosphanyl)methanide anions act as bidentate ligands via the phosphorus atoms. Lithiation of H(2)C(PPh(2)-BH(3))(2) in diethyl ether leads to the formation of [(Et(2)O)(2)Li{CH(PPh(2)-BH(3))(2)}] () which can be recrystallized from 1,2-dimethoxyethane (DME) leading to the formation of solvent-separated [(dme)(3)Li](+) [HC(PPh(2)-BH(3))(2)](-) ('). The reaction of with KOtBu and then with anhydrous CaI(2) yields [(thf)Ca{CH(PPh(2)-BH(3))(2)}(2)] (). In compound a Ca-C bond of 2.754(3) A is observed in the solid state to only one of the anions whereas the other anion only binds via the borane units.