Alkali metal compounds of a gallium(I) carbene analogue {:Ga[N(Ar)C(Me)]2} (Ar=2,6-iPr2C6H3)

A galliumdichloro complex (L center dot(-)) (GaCl2)-Cl-III (1) withan alpha-diimine ligand [(2,6-(Pr2C6H3)-Pr-i)NC(Me)](2) (L-0 represents the neutral ligand, L center dot- is the radical-anionic form of the ligand, and L represents its dianion L2-) was used to synthesize a series of alkali metal complexes of an N-heterocyclic carbenes (NHCs)-like gallium(I) species. Reduction of the precursor 1 with three equivalents of Na, Li, K or KC8, respectively, in THF gave the complexes [(LGaNa)-Na-I(THF)(3)] (2), [ (LGaLi)-Li-I(THF)(3)] (3), [LGaI{mu(2)-K(THF)(4)}(GaL)-L-I][K(THF)(6)] (4) and [LGaI(mu(2)-K){mu(2)-K(THF)(2)}(GaL)-L-I] (5). In these complexes, the original radical-anionic ligand was further reduced to the dianion, whereas the GaIII ion was reduced to Ga-I to yield the NHCs analogue [:GaN2C2](-), which then coordinated to alkali metal ions to form the complexes 2-5. Single crystal X-ray diffraction analyses revealed that these complexes feature direct Ga-M bonds (M=Li, Na, and K), which have also been studied by DFT computations. (C) 2011 Elsevier B.V. All rights reserved.