Multiply-bonded Group 14 compounds

The lack of stability of terminal oxo compounds of the heavier Group 5 metals led us naturally to the door of the isoelectronic imido (NR) ligand, where the availability of a substituent attached to the multiply-bonded group would allow both steric and electronic modulation of the products stability and reactivity. There had been a handful of half-sandwich imido complexes of the Group 5 metals synthesised by other workers, especially for vanadium and tantalum, but at that time none were known for niobium. A half-sandwich imido compound of niobium we considered, therefore, a prime target. 

Ge=P —, >Ge = 0, >Ge=S (Se, Te), and >Ge=C=X. In every chapter we will describe the new routes to such doubly bonded derivatives, their physical data together with theoretical calculations, and their reactivity. Only the doubly bonded compounds between germanium and main group elements are described. Thus, the derivatives in which the germanium is multiply bonded to a transition metal are not reported here. 

This chapter outlines the recent progress in the chemistry of multiply bonded species of Ge, Sn, and Pb. As can be concluded from this chapter and related recent reviews which deal with the chemistry of this family of compounds which are stable at room temperature, the field of low-coordinated species of heavier group 14 elements has matured considerably in recent years. 

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