Abstract
13C, 15N, and 29Si NMR chemical shifts have been computed for selected X-substituted silatranes (X=Cl, F, H, CH3) using Gauge-Including Atomic Orbitals (GIAO) at the Hartree-Fock level of theory. The isotropic 13C chemical shifts are largely insensitive to substituent-induced structural changes. In this study, the isotropic 13C chemical shifts between 1-methyl- and 1-hydrogensilatranes by GIAO-SCF calculation at the HF/6-31G level are very similar. But the results of 1-chloro- and 1-fluorosilatranes are about 4 ppm different from the experimental values. In contrast, the isotropic 15N and 29Si chemical shifts and the chemical shielding tensors are quite sensitive to substituent-induced structural changes. These trends are consistent with those of the experiment. The isotropic 15N chemical shift demonstrates a very clear correlation with Si-N distance. But in case of 29Si the correlations are not as clean as for the 15N chemical shift; the calculated variation in the 29Si chemical shift is much larger.