Quantum Crystallography: Current Developments and Future Perspectives

Crystallography and quantum mechanics have always been tightly connected because reliable quantum mechanical models are needed to determine crystal struc- tures. Due to this natural synergy, nowadays accurate distri- butions of electrons in space can be obtained from diffrac- tion and scattering experiments. In the original definition of quantum crystallography (QCr) given by Massa, Karle and Huang, direct extraction of wavefunctions or density matri- ces from measured intensities of reflections or, conversely, ad hoc quantum mechanical calculations to enhance the ac- curacy of the crystallographic refinement are implicated. Nevertheless, many other active and emerging research areas involving quantum mechanics and scattering experi- ments are not covered by the original definition although they enable to observe and explain quantum phenomena as accurately and successfully as the original strategies. There- fore, we give an overview over current research that is relat- ed to a broader notion of QCr, and discuss options how QCr can evolve to become a complete and independent domain of natural sciences. The goal of this paper is to initiate dis- cussions around QCr, but not to find a final definition of the field

On the Electronic Structure of mer,trans−[RuCl3(1H−indazole)2(NO)]mer,trans-[RuCl_{3}(1 H -indazole)_{2}(NO)], a Hypothetical Metabolite of the Antitumor Drug Candidate KP1019: An Experimental and DFT Study

The study reported herein focused on the electronic structure of the {Ru(NO)}6 fragment and characterization of the oxidation state of ruthenium in mer,trans-[RuCl3(Hind)2(NO)] (1; Hind = 1H-indazole) resulting from the reaction of mer,trans-[RuCl3(H2O)(Hind)2] (2) with NO in acetone or solid-state Anderson rearrangement of (H2ind)2[RuCl5(NO)] at 180 °C. The results of X-ray diffraction, 1H, 13C, and 15N NMR, EPR, IR, and UV/Vis spectroscopy, cyclic voltammetry, magnetic susceptibility, and XANES/EXAFS as well as theoretical data have been critically analyzed. The localized orbitals, domain-averaged Fermi holes, frontier orbitals, Mulliken population, and quantum theory of atoms-in-molecules (QTAIM) analyses are presented. In addition, mer,trans-[RuIIICl3(H2O)(Hind)2] (2) and trans-[RuIICl2(Hind)4] (3) were experimentally and theoretically investigated as reference compounds. A complete active space SCF calculation was performed to estimate the extent of antiferromagnetic spin–spin coupling in 1. We found that the closed-shell structure {RuIII(NO)0}6 fits better to the physical/spectroscopic properties of 1, although {RuII(NO)+}6 is formally still suitable for describing the oxidation state of Ru in this entit

Quantum Crystallography: Current Developments and Future Perspectives

Crystallography and quantum mechanics have always been tightly connected because reliable quantum mechanical models are needed to determine crystal structures. Due to this natural synergy, nowadays accurate distributions of electrons in space can be obtained from diffraction and scattering experiments. In the original definition of quantum crystallography (QCr) given by Massa, Karle and Huang, direct extraction of wavefunctions or density matrices from measured intensities of reflections or, conversely, ad hoc quantum mechanical calculations to enhance the ac- curacy of the crystallographic refinement are implicated.Nevertheless, many other active and emerging research areas involving quantum mechanics and scattering experiments are not covered by the original definition although they enable to observe and explain quantum phenomena as accurately and successfully as the original strategies. Therefore, we give an overview over current research that is related to a broader notion of QCr, and discuss options how QCr can evolve to become a complete and independent domain of natural sciences. The goal of this paper is to initiate discussions around QCr, but not to find a final definition of the field