Non‐Nuclear Attractor in a Molecular Compound under External Pressure

Abstract

AbstractThe dimeric magnesium(I) compound [{(DipNacnac)Mg}2] [1, DipNacnac = (DipNCMe)2CH, Dip = 2,6‐diisopropylphenyl] has previously been shown to exhibit a non‐nuclear attractor (NNA) between the two Mg atoms in the molecular ground state by both experimental and theoretical electron‐density studies. To study the stability and characteristics of this topological entity, we have determined the molecular structure of 1 in the pressure range from 0.4 to 1.9 GPa by high‐pressure single‐crystal X‐ray diffraction. The central Mg–Mg bond contracts significantly in this range to 97 % of the value at ambient pressure and a temperature of 100 K. High‐level single‐point theoretical calculations with the resulting atomic coordinates show that the NNA is persistently present in the topology at all pressures and that the difference between the value of the electron density at the NNA and the Mg–NNA bond critical point (bcp) is close to a maximum at the Mg–Mg separation that is found experimentally.