Aluminum, gallium, and indium hydrazides and the generation of oligonuclear element-nitrogen cages: molecular intermediates on the way to element nitrides.

Organoelement aluminum, gallium, and indium hydrazides, R(2)ENHN(H)R' (E = Al, Ga, In), are easily available from the corresponding trialkylelement compounds, ER(3), and hydrazines, H(2)NN(H)R', via elimination of the respective hydrocarbons. Their diverse molecular structures are derived from four-, five-, or six-membered element-nitrogen heterocycles. Their stepwise thermolysis under carefully controlled conditions was shown to proceed along one of several different well-defined routes. Cleavage of the N-N bonds afforded aluminum or gallium imides, REN(H), with up to eight metal atoms in a single molecule, while preservation of the N-N bonds led to interesting cages in which intact N-N bonds of formally dianionic hydrazinediides bridge the metal atoms via their two adjacent donor atoms. Further thermolysis yielded the amorphous element nitrides via the gradual degradation of the hydrazinediide groups. Several intermediates have been isolated and provided insight in the course of these reactions. A particularly interesting compound was one that features a hydrazinetetraide unit, N-N, that is stabilized by coordination to six gallium atoms.