Towards accurate and precise positions of hydrogen atoms bonded to heavy metal atoms

Abstract

Positions and anisotropic thermal motion of H-Atoms bound to heavy atoms in transition-metal hydride complexes were successfully refined using Hirshfeld Atom Refinement (HAR) against low resolution X-ray diffraction data.

Different Reactivities of (5-Ph2P-Ace-6-)2MeSiH toward the Rhodium(I) Chlorides [(C2H4)2RhCl]2 and [(CO)2RhCl]2. Hirshfeld Atom Refinement of a Rh–H···Si Interaction

“…The results discussed for 1 are based on Hirshfeld atom refinement (HAR), and we present the first comparison of a standard HAR for a transition-metal hydride to a novel NoSpherA2 HAR . The standard HAR model (Figure , top left, HAR_standard) and the NoSpherA2 HAR model (Figure , top right, HAR_NoSpherA2) both include an anisotropic refinement of the hydrogen atom displacement parameters.…”

“…In contrast, in HAR_NoSpherA2 hydrogen atom H1 bonded to the Rh atom was subjected to a restraint in order to avoid a nonpositive-definite (NPD) anisotropic displacement parameter (ADP). The refinement of disordered components is also a new feature in NoSpherA2 and could here be applied to the cocrystallized difluorobenzene molecule. Details of both refinements are given in Tables S1 and S2 in the Supporting Information.…”

“…For the refinement of compounds with heavier elements, there are various experimental and theoretical hurdles (e.g., relativistic effects, Fourier truncation errors, accuracy of integration grids, absorption and radiation damage, etc.) that are currently being investigated in detail in the context of HAR. , A novel implementation of HAR within the software NoSpherA2 inside Olex2 allows the use of more accurate integration grids and more flexible theory for heavy elements as well as restraints for hydrogen atoms . Only recently, heavy metal hydrides could be refined and the advantages and pitfalls were discussed .…”

“…that are currently being investigated in detail in the context of HAR. , A novel implementation of HAR within the software NoSpherA2 inside Olex2 allows the use of more accurate integration grids and more flexible theory for heavy elements as well as restraints for hydrogen atoms . Only recently, heavy metal hydrides could be refined and the advantages and pitfalls were discussed . Here, we compare the standard HAR procedure and the NoSpherA2 HAR procedure for the refinement of the Rh–H···Si group and discuss the advantages and disadvantages of freely refined versus restrained treatments of hydrogen atoms bonded to heavy elements.…”

New venues in electron density analysis

“…Then, the atomic coordinates and the thermal parameters are refined with the usual least-squares procedure, and the process is repeated until convergence. One of the most relevant benefits of HAR is its ability to refine anisotropically hydrogen atoms 88,89 which, as mentioned before, is unfeasible with IAM and MM. As an example, the bond critical point corresponding to the intramolecular HÁ Á ÁH interaction in biphenyl, and the corresponding ring critical point (red and yellow spheres, respectively), are compared in Fig.…”