The first C(O)NHP(O)-based phosphoric triamide structure with an N‒H···π hydrogen bonding: A combination of X-ray crystallography and theoretical study to evaluate the strength of hydrogen bonds

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.

A combined X-ray crystallography and theoretical study of N-H...OX (X is =P and -C) hydrogen bonds in two new structures with a (C-O)2(N)P(=Y) (Y is O and S) skeleton

The crystal structures of N,N'-(cyclohexane-1,4-diyl)bis(O,O'-diphenylphosphoramide), C₃₀H₃₂N₂O₆P₂ or (C₆H₅O)₂P(O)(1-NH)(C₆H₁₀)(4-NH)P(O)(OC₆H₅)₂, (I), and N,N'-(1,4-phenylene)bis(O,O'-dimethylthiophosphoramide), C₁₀H₁₈N₂O₄P₂S₂ or (CH₃O)₂P(S)(1-NH)(C₆H₄)(4-NH)P(S)(OCH₃)₂, (II), have been investigated. In the structure of (I), with an (O)₂(N)P(O) skeleton, two symmetry-independent phosphoramide molecules are linked through N-H...O=P hydrogen bonds. In the structure of (II), with an (O)₂(N)P(S) skeleton, the ester O atoms take part in N-H...O-C hydrogen bonds as acceptors; the P=S groups do not participate in hydrogen-bonding interactions. The strengths of these hydrogen bonds were evaluated, using quantum chemical calculations with the GAUSSIAN09 software package at the B3LYP/6-311G(d,p) level of theory. For this, LP(O) to σ*(NH) charge transfers were studied, according to the second-order perturbation theory in natural bond orbital (NBO) methodology, for a three-component cluster of hydrogen-bonded molecules for both structures, including all of the independent N-H...O hydrogen bonds observed in the crystal packing. The details of the intermolecular interactions were studied by Hirshfeld surface maps and two-dimensional fingerprint plots.

Evaluation of N-H...S and N-H...π interactions in O,O'-diethyl N-(2,4,6-trimethylphenyl)thiophosphate: a combination of X-ray crystallographic and theoretical studies

In the crystal structure of O,O'-diethyl N-(2,4,6-trimethylphenyl)thiophosphate, C₁₃H₂₂NO₂PS, two symmetrically independent thiophosphoramide molecules are linked through N-H...S and N-H...π hydrogen bonds to form a noncentrosymmetric dimer, with Z' = 2. The strengths of the hydrogen bonds were evaluated using density functional theory (DFT) at the M06-2X level within the 6-311++G(d,p) basis set, and by considering the quantum theory of atoms in molecules (QTAIM). It was found that the N-H...S hydrogen bond is slightly stronger than the N-H...π hydrogen bond. This is reflected in differences between the calculated N-H stretching frequencies of the isolated molecules and the frequencies of the same N-H units involved in the different hydrogen bonds of the hydrogen-bonded dimer. For these hydrogen bonds, the corresponding charge transfers, i.e. lp (or π)→σ*, were studied, according to the second-order perturbation theory in natural bond orbital (NBO) methodology. Hirshfeld surface analysis was applied for a detailed investigation of all the contacts participating in the crystal packing.