A novel tubular hydrogen-bond pattern in a new diazaphosphole oxide: a combination of X-ray crystallography and theoretical study of hydrogen bonds

Abstract

In the structure of 2-(4-chloroanilino)-1,3,2λ4-diazaphosphol-2-one, C12H11ClN3OP, each molecule is connected with four neighbouring molecules through (N—H)2...O hydrogen bonds. These hydrogen bonds form a tubular arrangement along the [001] direction built from R 3 3(12) and R 4 3(14) hydrogen-bond ring motifs, combined with a C(4) chain motif. The hole constructed in the tubular architecture includes a 12-atom arrangement (three P, three N, three O and three H atoms) belonging to three adjacent molecules hydrogen bonded to each other. One of the N—H groups of the diazaphosphole ring, not co-operating in classical hydrogen bonding, takes part in an N—H...π interaction. This interaction occurs within the tubular array and does not change the dimension of the hydrogen-bond pattern. The energies of the N—H...O and N—H...π hydrogen bonds were studied by NBO (natural bond orbital) analysis, using the experimental hydrogen-bonded cluster of molecules as the input file for the chemical calculations. In the 1H NMR experiment, the nitrogen-bound proton of the diazaphosphole ring has a high value of 17.2 Hz for the 2 J H–P coupling constant.