New Ga/N-based Active Lewis Pairs, Trifunctional Ga-Ga Compounds, Reactions with Cyanamide and Dual Insertion of Isocyanate

Hydrogallation of Me3Si-C equivalent to C-NR'(2) with R2Ga-H (R = tBu, CH(2)tBu, iBu) yielded Ga/N-based active Lewis pairs, R2Ga-C(SiMe3)=C(H)-NR'(2) (7). The Ga and N atoms adopt cis-positions at the C=C bonds and show weak Ga-N interactions. tBu(2)GaH and Me3Si-C equivalent to C-N(C2H4)(2)NMe afforded under exposure of daylight the trifunctional digallium(II) compound [MeN(C2H4)(2)N](H)C=C(SiMe3)Ga(tBu)-Ga(tBu)C(SiMe3)=C(H)[N(C2H4)(2)NMe] (8), which results from elimination of isobutene and H-2 and Ga-Ga bond formation. 8 was selectively obtained from the ynamine and [tBu(H)Ga-Ga(H)tBu](2)[HGatBu(2)](2). 7a (R = tBu; NR'(2) = 2,6-Me2NC5H8) and H8C4N-C equivalent to N afforded the adduct tBu(2)Ga-C(SiMe3)=C(H)(2,6-Me2NC5H8)center dot N equivalent to C-NC4H8 (11) with the nitrile bound to gallium. The analogous ALP with harder Al atoms yielded an adduct of the nitrile dimer or oligomers of the nitrile at room temperature. The reaction of 7a with Ph-N=C=O led to the insertion of two NCO groups into the Ga-C-vinyl bond to yield a GaOCNCN heterocycle with Ga bound to O and N atoms (12).