LONG-RANGE J(N-15,C-13) AND J(C-13,C-13) COUPLING-CONSTANTS VIA THE METAL ATOM IN C-13 NMR-SPECTRA OF SQUARE-PLANAR NI(II) COMPLEXES OF THESCHIFF-BASE OF (S)-2-(N-BENZYLPROLYL)AMINOBENZOPHENONE AND C-13-1-LABELED, C-13-2-LABELED OR N-15-LABELED GLYCINE

Chiral synthons containing either C-13- Or N-15-labelled glycine were prepared. The C-13 and N-15 NMR spectra of the Ni(II) complex of the S chiff base of (S)-2-(N-benzylprolyl)aminobenzophenone and C-13-1-, C-1 3-2- or N-15-labelled glycine were measured and assigned. The observed splitting of the carbon signals is due to long-range J(C-13,C-13) and J(N-15,C-13) couplings. The mutual influence of nuclei is transferred via the central Ni(II) atom in square-planar complexes. (C) 1998 John Wiley & Sons, Ltd.