The reactivity of a series of Ga(), Ga() and Ga() heterocyclic compounds towards a number of Group 15 substrates has been investigated with a view to prepare examples of gallium-terminal pnictinidene complexes. Although no examples of such complexes were isolated, a number of novel complexes have been prepared. The reactions of the gallium() N-heterocyclic carbene analogue, [K(tmeda)][:Ga{[N(Ar)C(H)]}] (Ar = 2,6-diisopropylphenyl) with -(PPh) and PhN[double bond, length as m-dash]NPh led to the unusual anionic spirocyclic complexes, [{[small kappa],[prime or minute]-(PhP)}Ga{[N(Ar)C(H)]}] and [{[small kappa],-PhNN(H)(CH)}Ga{[N(Ar)C(H)]}], formal reductions of the Group 15 substrate. The reaction of the digallane(4), [Ga{[N(Ar)C(H)]}], with (MeSi)N afforded the paramagnetic, dimeric imido-gallane complex, [{[N(Ar)C(H)[radical dot]]}Ga{[small mu ]-N(SiMe)}], a Ga-Ga bond insertion process. In addition, the new gallium() phosphide, [GaI{P(H)Mes*}{[N(Ar)C(H)][radical dot]}], Mes* = CHBu-2,4,6; was prepared and treated with diazabicycloundecane (DBU) to give [Ga(DBU){P(H)Mes*}{[N(Ar)C(H)]}], presumably a gallium-terminal phosphinidene intermediate, [Ga{[double bond, length as m-dash]PMes*}{[N(Ar)C(H)][radical dot]}]. The possible mechanisms of all reactions are discussed, all new complexes have been crystallographically characterised and all paramagnetic complexes have been studied by ENDOR and/or EPR spectroscopy.