The synergistic co-operation of N-H...O=P hydrogen bonds and C-H...OX weak intermolecular interactions (X is =P or -C) in the (CH3O)2P(O)(NH-NHC6F5) amidophosphoester: a combined X-ray crystallographic and theoretical study.

The asymmetric unit of O,O'-dimethyl [(2,3,4,5,6-pentafluorophenyl)hydrazinyl]phosphonate, C8H8F5N2O3P, is composed of two symmetry-independent molecules with significant differences in the orientations of the C6F5 and OMe groups. In the crystal structure, a one-dimensional assembly is mediated from classical N-H...O hydrogen bonds, which includes R22(8), D(2) and some higher-order graph-set motifs. By also considering weak C-H...O=P and C-H...O-C intermolecular interactions, a two-dimensional network extends along the ab plane. The strengths of the hydrogen bonds were evaluated using quantum chemical calculations with the GAUSSIAN09 software package at the B3LYP/6-311G(d,p) level of theory. The LP(O) to σ*(NH) and σ*(CH) charge-transfer interactions were examined according to second-order perturbation theory in natural bond orbital (NBO) methodology. The hydrogen-bonded clusters of molecules, including N-H...O and C-H...O interactions, were constructed as input files for the calculations and the strengths of the hydrogen bonds are as follows: N-H...O [R22(8)] > N-H...O [D(2)] > C-H...O. The decomposed fingerprint plots show that the contribution portions of the F...H/H...F contacts in both molecules are the largest.