Borane adducts of the water soluble phosphine PTA (PTA = 1,3,5-triaza-7-phosphaadamantane)

Boronation of the water soluble phosphine PTA (PTA = l,3,5-triaza-7-phosphaadamantane) in dry THF easily affords the N-boronated adduct N-B-PTABH3 which represents the first N-coordinated adduct of this popular water soluble phosphine (N-B-PTABH3 = 1-boranyl-1,3,5-triaza-7-phosphaadamantane). In situ 31P NMR spectroscopy suggests the occurrence of a stepwise boronation resulting in the addition of as many as four equivalents of BH3 to PTA to give the polyboranyl species Nx, Py-B-PTA(BH3)(x+y) (x = 1-3, y = 0, 1). Hydrolysis of the monoboranyl adduct occurs slowly in the presence of water yielding back PTA and boric acid, H3BO3.