STRUCTURAL CHEMISTRY OF LITHIUM HYDRAZIDES

Deprotonation of NH protons of four diorgano-, organo(trimethylsilyl)- and bis(trimethylsilyl)hydrazines by n-butyllithium in hexane led to the following lithium hydrazides: [Et(Li)N-N(H)Et](6) (1)(6), [Me(3)Si (Li)N-N(Li)SiMe3(3)](4), (2)(4), [Me(3)Si-(Li)N-N(Li)SiMe(3) . (Me(3)S i)(2)N-N(Li)SiMe(3)](2) (3)(2), and [Ph(Li)N-N(Li)SiMe(3)](4), (4)(4), respectively. The structure determination by X-ray methods at low tem perature reveals butterfly-shaped Li2N2 structural monomeric units whi ch associate through ''laddering'' to the observed oligomers thereby g enerating penta- and hexacoordinated Li centers. N-N bonds lengths of up to 1.556 Angstrom suggest that negative charge accumulates at the n itrogen atoms of (1)(6), (2)(4), and (3)(2). An amazing structure show s the red compound 4 where two Li ions are pi-sandwiched between two p henyl groups each. The compound can be looked at as a new type of a li thium lithiate complex, Li-2[Li(6)N(8)Ph(4)(SiMe(3))(4)], but short N- C and N-N bonds in the Li6N8 core indicate that its negative charge is transferred to the phenyl groups.