Monomeric Alkali Metal (Li, Na, K) Complexes of Bis(iminophosphorano)methanides

The reaction of the bis(iminophosphorano)methane, CH2(Cy2PNSMe3)2 (1), with methyllithium (even with excess of the latter) gave the monomeric methanide complex [Li{HC(Cy2PNSiMe3)2-κC,κN,κN‘}(OEt2)] (2) in a good yield. The reaction of H2C(Ph2PNSiMe3)2
(2) with equimolar equivalents of NaH or KH in THF solvent yielded monomeric [M{HC(Ph2PNSiMe3)2-κN,κN‘}(THF)2] (M = Na, 4; K, 5) with evolution of hydrogen gas. The crystal
structures of each complex show the development of a unique coordination sphere around
each alkali metal. In the lithium complex, 3, the central carbon atom of the ligand is bound
to the metal, but such interaction does not occur in the case of either the Na, 4, or the K, 5,
complexes. However in the potassium complex, one of the phenyl rings of the ligand is
π-coordinated to the metal.