Competition among weak C–H⋯O/S/H interactions in the crystal structure of {(C2H5O)2P(S)}2N2C4H8 bis(thiophosphoramide): experimental/computational studies

Abstract

Supramolecular assembly driven by weak C–H⋯SP/O and CH⋯HC contacts was studied in a new bis(thiophosphoramide) structure, {(C₂H₅O)₂P(S)}₂N₂C₄H₈, using X-ray crystallography and DFT computational methods. Combined QTAIM/noncovalent interaction (NCI) and natural bond orbital (NBO) analyses were used to gain deeper insights into the nature, energy and strengths of these contacts. The C–H⋯O hydrogen bond was found to be the strongest interaction, followed by two H⋯H and then H⋯S contacts. Crystal lattice energy calculations were performed, and the components contributing to the intermolecular interactions were investigated and discussed (electrostatic, polarization, dispersion and repulsion). The dispersion forces were found to be the most prominent in the network energy. The relative contributions of the intermolecular contacts were visualized by Hirshfeld surfaces and two-dimensional fingerprint diagrams. Some topics related to geometry and conformation were also studied.