Molecular orbitals strictly localized on small molecular fragments from X-ray diffraction data

Nowadays, the electron density is recognized as a fundamental property that contains most of the information concerning the electronic structure of molecules, and, therefore, its determination from high-resolution X-ray diffraction data is becoming more and more important. In this context, we propose a new strategy for the charge density analysis, strategy in which the chemical interpretability of the multipole model is combined with the quantum mechanical rigor of the wave function-based approaches. In particular, this novel technique aims at extracting molecular orbitals strictly localized on small molecular fragments (e.g., atoms, bonds, or functional groups) from a set of measured structure factors amplitudes. Preliminary tests have shown that their determination is really straightforward and, given their reliable transferability, we envisage the possibility of constructing new extremely localized molecular orbital databases as an alternative to the existing pseudoatom libraries. © 2013 American Chemical Society.