Ab initio prediction of15N-NMR chemical shift in ?-boron nitride based on an analysis of connectivities

✍ Scribed by Gastreich, Marcus; Marian, Christel M.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 271 KB
• Volume: 19
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/(sici)1096-987x(199805)19:7<716::aid-jcc3>3.0.co;2-t

✦ Synopsis

Hydrogen-saturated cut-outs of hexagonal boron nitride have been used to model the solid state. Model compounds have been geometry optimized by means of density functional theory, whereas chemical shift calculations have been carried out at the coupled-perturbed Hartree᎐Fock level Ž . of theory employing gauge-including atomic orbital GIAO basis sets. The reliability of results has been tested against experimental values for chemical shifts in stable molecules with similar structural elements. With increasing cluster size, viz. a vanishing influence of the saturating hydrogens on the innermost nitrogen atoms, we find a convergence of 15 N chemical shifts. A classification scheme for the chemical environment of a nitrogen atom has been set up according to its bonding graph including the second coordination sphere. For a given connectivity, chemical shifts vary within a few parts per million, thus enabling us to predict a 15 N-NMR chemical shift of y285 " 5 ppm for solid ␣-boron nitride.