Synthesis and crystal structure determination of two monomeric alkali metal phosphide derivatives: [M{P(H)C6H2-t-Bu-3-2,4,6}(18-crown-6)] (M = K or Rb)

The molecular structures of two crown ether adducts of heavier alkali metal derivatives (M=K or Rb) of the primary phosphane "supermesitylphosphane" [ i.e. H2PC6H2-t-Bu-3-2,4,6] have been determined. The complexes [M{P(H)C6H2- t-Bu-3-2,4,6}(18-crown-6)] [M=K 1 or Rb 2] were obtained in good yield by c rystallization of MP(H)C6H2-t-Bu-3-2,4,6 from toluene-18-crown-6. A main fe ature is the crown ether adducts of bent MP(H)C6H2-t-Bu-3-2,4,6 moieties, t hereby representing rare examples of monomeric complexes of the heavier alk ali metals containing a phosphide ligand. Both solution and solid-state NMR data are presented.