High-Pressure Structure and Properties of N,N-Dimethylformamide (DMF)

Intermolecular interactions and aggregation in compressed N,N-dimethylformamide (DMF, C3H7NO, mp 212.7 K) have been determined in the solid state by single-crystal X-ray diffraction. The crystals of DMF were obtained under high-pressure isochoric conditions (the structure was determined up to 1.7 GPa) and under low-temperature isobaric conditions (the structure was determined down to 100 K). The exceptional stability of the DMF structure has been connected with its large number of degrees of freedom, due to the low triclinic symmetry of the crystal and two symmetry-independent molecules. Consequently, the distortions of different CH center dot center dot center dot O bonds linking the molecules into one-dimensional aggregates, and their mutual displacements, efficiently compensate the structural strains generated by pressure.