Analysis of multinuclear lanthanide-induced shifts. Part 2. The geometry of ketone binding to lanthanides

Abstract

Multinuclear lanthanide-induced shifts for a variety of Ln(fod)₃ shift reagents have been combined with Gd(fod)₃-induced longitudinal relaxation-rate enhancements in geometry calculations for lanthanide adducts of adamantanone. The experimental results are most consistent with an Ln–O–C angle of about 180° and an Ln–O distance of approximately 2.5 Å. The fit between calculated and experimental data is very soft, and simulated data indicate that this is characteristic of the linear Ln–O–C array. When induced shifts and relaxation rate enhancements are simulated for nonlinear co-ordination geometries, the results are inconsistent with the experimental data.