Gallium Hydride‐Catalyzed Selective Hydroboration of Unsaturated Organic Substrates

The first examples of tetrasubstituted conjugated bis‐guanidinate (CBG) supported monomeric and thermally stable gallium dihalides [LGaX 2 ], (X=Cl ( Ga−Cl ), I ( Ga−I )) and dihydride ( Ga−H ) [LGaH 2 ] (where L={(ArHN)(ArN)−C=N−C=(NAr)(NHAr)}; Ar=2,6‐Et 2 −C 6 H 3 ) compounds are reported. The reaction of in situ generated LLi with 1.0 equiv. GaX 3 (X=Cl, I) afforded compounds Ga−Cl and Ga−I . The reaction between Ga−Cl and Li[HBEt 3 ] in benzene yielded the dihydride compound Ga−H . All reported compounds ( Ga−Cl , Ga−I , and Ga−H ) were characterized by NMR, HRMS, and single‐crystal X‐ray diffraction studies. Ga−H was probed for the hydroboration of carbodiimides (CDI), isocyanates, and isothiocyanates with HBpin. Compound Ga−H was also found effective for the catalytic hydroboration of imines, nitriles, alkynes, esters, and formates, affording the corresponding products in quantitative yields. Stoichiometric reactions with a CDI were performed to establish the catalytic cycle.