Reactions of a n Amino Imino Borane with Phosphinic. Phosphonic, and Phosphoric Acids Controlled 1: 1 reactions of R,P(O)OH with tmp -B = NtBu (1) while H3P04 reacts with 1 to yield OP[OB(tmp)NHtBu], (6).(tmp = 2,2,6,6-tetramethylpiperidino group) in hexane leads Species containing tetracoordinated boron atoms are formed to R2P(0)OB(tmp)NHtBu (2). In most other cases mixtures of 2 as well in dichloromethane as a solvent. Spectral data for the with other products are obtained. Application of a 4 : l ratio compounds 2, 4, and 6 reveal three-coordinate boron atoms, of Me2P (0)