CHEMICAL-SHIFT BOND DERIVATIVES FOR MOLECULES CONTAINING 1ST-ROW ATOMS

The primary and secondary first and second derivatives of the NMR isotropic chemical shift with respect to bond length modification have been calculated in the gauge invariant atomic orbital (GIAO) perturbed Hartree-Fock approach for some 177 first-row nuclei in 63 molecules using the mixed basis heavy:6-311G(d)/hydrogen:4-31. The shift derivative with respect to multiple bond length changes correlates linearly with the shift itself while changes involving single bonds behave differently. Agreement between experimental derivatives and those calculated theoretically is good, but the calculations show that second derivatives as well as both types of secondary effects cannot always be neglected. The correlation between the shift derivative and the isotropic shift indicates an exponential variation of the chemical shift with bond length near the vicinity of the equilibrium structure for multiple bonds.