Puckering behavior in six new phosphoric triamides containing aliphatic six- and seven-membered ring groups and a database survey of analogous ring-containing structures

The influence of a N heteroatom on the ring conformations of six- and seven- membered aliphatic rings in six new C(O)NHP(O)-based phosphoric triamide structures (analysed by X-ray crystallography) is investigated. Additionally the influence of steric and crystal packing effects is also studied by the analysis of Hirshfeld surfaces. The results are compared to analogous structures with three- to seven- aliphatic membered rings deposited in the Cambridge Structural Database. In the newly determined structures, the six-membered rings only show the near-chair conformation with a maximum deviation of the θ puckering parameter of 4.4° from the ideal chair value of 0°/180°, while the seven-membered rings are found in different conformations such as near-chair, twist chair and twist sofa

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