O-Phenyl (tert-butyl-amido)(p-tolyl-amido)-phosphinate.

In the title mol-ecule, C(17)H(23)N(2)O(2)P, the P atom has a distorted tetra-hedral environment. The P-N bond to the tolyl-amido fragment is 1.642 (4) Å while that to the butyl-amido fragment is 1.629 (3) Å. The dihedral angle between the two benzene rings is 82.3 (2)°. In the crystal, adjacent mol-ecules are linked via weak N-H⋯(O)P and N-H⋯N hydrogen-bonding inter-actions into an extended chain parallel to the b axis. The three methyl groups of the tert-butyl-amido substituent are disordered over two sets of sites with equal occupancies. The crystal studied was found to be a non-merohedral twin with the minor twin component = 23.1 (1)%.