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

Dalton Transactions Pub Date: 2009-02-27 DOI: 10.1039/B822530C

Abstract

The reaction of Li{HC(PPh2)2}, which forms [(tmeda)(thf)Li{HC(PPh2)2}] (1) in the presence of appropriate Lewis bases, with KOtBu and CaI2 in THF yields [(thf)3Ca{CH(PPh2)2}2] (2). In complexes 1 and 2 the bis(diphenylphosphanyl)methanide anions act as bidentate ligands via the phosphorus atoms. Lithiation of H2C(PPh2-BH3)2 in diethyl ether leads to the formation of [(Et2O)2Li{CH(PPh2-BH3)2}] (3) which can be recrystallized from 1,2-dimethoxyethane (DME) leading to the formation of solvent-separated [(dme)3Li]+ [HC(PPh2-BH3)2]? (3′). The reaction of 3 with KOtBu and then with anhydrous CaI2 yields [(thf)Ca{CH(PPh2-BH3)2}2] (4). In compound 4 a Ca–C bond of 2.754(3) ? is observed in the solid state to only one of the anions whereas the other anion only binds via the borane units.

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