Investigations into the preparation of groups 13–15 N-heterocyclic carbene analogues

Attempts have been made to prepare a variety of groups 13–15 N-heterocyclic carbenoid systems. The work in group 13 led to two structurally characterized, paramagnetic gallium(III) heterocycles, [I2Ga{[N(R)C(Me)]2}], R = C 6 H 3 Pr 2 i - 2 , 6 ( Ar ) or C6H3(C6H4But-4)2-2,6. Reduction of the former gave the anionic gallium(I) heterocyclic complex, [K(tmeda)][:Ga{[N(Ar)C(Me)]2}], which was oxidatively coupled, affording the structurally characterized digallane(4), [Ga{[N(Ar)C(Me)]2}]2. From group 14, the new germanium(IV) heterocycle, [Cl2Ge{[N(Ar)C(H)]2}], and the N-heterocyclic germylene, [:Ge{[N(Ar)C(H)]2}], have been prepared and fully characterized. Attempts to prepare N-heterocyclic silylene, phosphenium and arsenium compounds were unsuccessful and led instead to the silyl, phosphino and arsino-substituted ene-amines, [(ClnE)2{μ-[N(Ar)C(H)]2}], E = Si, n = 3; E = P or As, n = 2.