An Isolable Gallium-Substituted Nitrilimine and its Reactivity with B-H, Si-H and B-B Bonds.

Reaction of the Ga(I) compound NacNacGa (9) with the diazo compound N2 CHSiMe3 affords the nitrilimine compound NacNacGa(N-NCSiMe3 )(CH2 SiMe3 ) (10). Carrying out this reaction in the presence of pyridine does not lead to C-H activation on the transient alkylidene NacNacGa=CHSiMe3 but generates a metallated diazo species NacNacGa(NHN=CHSiMe3 )(CN2 SiMe3 ) (13) that further rearranges into the isonitrile compound NacNacGa(NHN=CHSiMe3 )(N(NC)SiMe3 ) (15). Reactions of 10 with the silane H3 SiPh and the borane HBcat furnished products of 1,3 addition to the nitrilimine moiety NacNacGa{N(ERn )NCSiMe3 }(CH2 SiMe3 ), whereas reaction with the diborane B2 cat2 gave the product of formal nitrene insertion into the B-B bond. DFT calculations suggest that the interaction of 9 with N2 CHSiMe3 proceeds through intermediate formation of an alkylidene compound that undergoes CH activation with a second molecule of N2 CHSiMe3 . Insertion into the B-B bond likely proceeds through an initial 1,3-addition of the diborane, followed by boryl migration to the former nitrene center.