Structural chemistry of alkali metal phenylhydrazides

The crystal and molecular structures of a series of N-phenyl-substituted lithium hydrazides were determined in order to investigate possible Li Ph pi interactions. These are pronounced when there are no donor molecules present to solvate the Li centers. An eta(6)-Li ... Ph interaction is particularly distinct in tetrameric (Me(3)Si)(2)N-N(Ph)Li but also in trimeric Ph(2)N-N(SiMe(3))Li. Deprotonation of N,N'-diphenylhydrazine with butyllithium in ether resulted in the formation of Ph(Li)N-N(Ph)Li . 2 LiNPh(2) . 2 OEt(2) with phenyl group migration and N-N bond cleavage by a redox process. An increase of the size of the cations, as shown for Ph(Me(3)-Si)N-N(Ph)Na . NH3 and the caesium salt (Me(3)-Si)(2)N-N(Ph)Cs . nTHF, results in increased coordination of the metal ion to the phenyl group. The caesium compound forms a three-dimensional network. Channels along the c axis are partially filled with THF molecules.