Syntheses and X-ray structures of monocyclic, bicyclic, and spirocyclic gallium and indium boraamidinates

The reactions of jLi(2)[PhB((NBu)-Bu-t)(2)]}(2) with GaCl3 in various stoichiometries yield [Li(thf)(4)][PhB(mu-(NBu)-Bu-t)(2)GaCl2.GaCl3] (1), [PhB(mu-(NBu)-Bu-t)(2)GaCl](2) (2), and {mu-Li(OEt2)[PhB((NBu)-Bu-t)(2)]Ga} (3a), a series of complexes in which the three chloride ligands are successively replaced by the dianion [PhB((NBu)-Bu-t)(2)](2-). The X-ray structures of 1, 2, and 3a show that the boraamidinate ligand adopts an N, N'-chelating mode. In the ion-separated complex 1, one of the nitrogen atoms is coordinated to a GaCl3 molecule, The related indium complexes [mu-LiCl(thf)(2)][PhB(mu-(NBu)-Bu-t)(2)lnCl](2) (4) and {mu-Li(OEt2)[PhB(mu-(NBu)-Bu-t)(2)]In} (3b) were obtained in a similar manner. Complex 4 is the indium analogue of 2 with the incorporation of a bissolvated LiCl molecule. In 3a and 3b the spirocyclic {[PhB(mu-(NBu)-Bu-t)(2)](2)M}(-) (M = Ga, In) anions are N, N'-chelated to the [Li(OEt2)](+) counterion. Prolonged reactions result in the formation of [PhB(muN(t)Bu)(2)GaCl][(BuN)-Bu-t(H)GaCl2] (5) and {[PhB(mu-(NBu)-Bu-t)(2)lnCl][(BuN)-Bu-t(H)InCl2][mu-LiCl(OEt2)(2)]} (6), respectively. The X-ray structures of 5 and 6 reveal bicyclic structures which formally involve the entrapment of the monomers (BuN)-Bu-t(H)MCl2 by a four-membered BN2M ring (M = Ga, In). The synthesis and X-ray structure Of Cl2Ga[mu-N(H)Bu-t](2)GaCl2 are also reported.