Bond length variation in hydronitride molecules and nitride crystals

Abstract

Abstract. Bond lengths calculated for the coordination polyhedra in hydronitride molecules match average values observed for XN bonds involving main group X-cations in nitride crystals to within ~ 0.04 ~. As suggested for oxide and sulfide molecules and crystals, the forces that determine the average bond lengths recorded for coordinated polyhedra in hydronitride molecules and nitride crystals appear to be governed in large part by the atoms that comprise the polyhedra and those that induce local charge balance. The forces exerted on the coordinated polyhedra by other parts of the structure seem to play a small if not an insignificant role in governing bond length variations. Bonded radii for the nitride ion obtained from theoretical electron density maps calculated for the molecules increase linearly with bond length as observed for nitride crystals with the rock salt structure. Promolecule radii calculated for the molecules correlate with bonded and ionic radii, indicating that the electron density distributions in hydronitride molecules possess a significant atomic component, despite bond type.

A Computational Quantum Chemical Study of the Bonded Interactions in Earth Materials and Structurally and Chemically Related Molecules

“…The value of rb(O) calculated for a MO bond in a earth material (Fig. 11a) is virtually the same as that calculated for a representative molecule or pro crystal (Gibbs et al 1992). For each case, rb(O) decreases linearly along separate trends with decreasing R(MO) and increasing electronegativity of the M-cation for each of the bonds.…”

“…Nitride, fluoride and sulfide bond strength and bond length variations Average bond lengths, <R(MX», observed for fluoride, nitride and sulfide MXv-, coordinated polyhedra in crystalline materials and calculated for related molecules have also been found to display similar correlations with p (Buterakos et al 1992;Nicoll et al 1994; Bartelmehs et al 1989). In each case, the expression was found to be of the same form, R = Kp-P, as observed for oxide crystals and molecules.…”

“…It is notable that the oxide anions in an earth material like danburite, CaB2ShOs, (Downs and Swope 1992;Gibbs et al 1992) are each observed to exhibit several different bonded radii with a radius of 0.96 A in the direction of Si, 0.98 A in the direction of Band 1.22 A in the direction of Ca. Actually, within this context, the term "radius" has little or no meaning in that the electron density distribution of the oxide anion is distorted rather dramatically from spherical symmetry (cf.…”

Visualizing Lithium‐Ion Migration Pathways in Battery Materials

“…For example, the simple expression R (MO)=1.39( s / r ) −0.22 obtained by a fit to theoretical data for hydroxy acid molecules (in which s is the Pauling bond strength and r the row number of the cation) holds for observed MO bond lengths in crystals35 for main‐group cations M from all six rows 36. It is notable that similar expressions have also been established for fluoride,37 nitride,38 and sulfide39 molecules and crystals.…”

Bond length estimates for oxide crystals with a molecular power law expression

“…2c), providing grounds for why the bond lengths scatter along a single trend plotted in terms of s/r. This argument also provides grounds for why the bond lengths for sulfides, nitrides and fluorides fall along a single trend when plotted in terms of s/r (Bartelmehs et al 1989;Buterakos et al 1992;Nicoll et al 1994). …”