ONE-BOND RH-103,N-15 COUPLING-CONSTANTS OF AXIAL AND EQUATORIAL LIGANDS IN RHODOXIMES

The Rh-103,N-15 coupling constants and N-15 chemical shifts of XRhIII( Hdmg)(2)L rhodoximes (Hdmg = dimethylglyoximate, L = PPh3 or pyridine, X = halide, alkyl, haloalkyl) were extracted from gradient-selected ( H-1,N-15)-HSQC experiments, Coupling between rhodium and the equatoria l oxime nitrogens is large (18-21 Hz) and shows little sensitivity to the nature of the cis-oriented ligands X and L, In contrast, coupling between rhodium and the axial pyridine nitrogen is small (6-9 Hz) for X = alkyl but increases to 16-18 Hz in the halide complexes ('trans in fluence'), The structural implications are discussed in conjunction wi th x-ray data. (C) 1997 John Wiley & Sons, Ltd.