Multinuclear NMR study of some organoplatinum complexes containing multifunctional azines as chelating ligands

1 H‐detected indirect NMR techniques were used to determine 15 N and 195 Pt NMR parameters for a series of organoplatinum(IV) complexes and one platinum(II) complex containing nitrogen‐based azobispyridine, bispyridyltetrazine, and bipyrimidine ligands. The inverse technique permitted the detection of small 4 J (Pt,H) and 5 J (Pt,H) long‐range couplings and the acquisition of 15 N NMR data in natural isotopic abundance via n J (N,H) intra‐ and inter‐ligand couplings, but failed in cases where coherence transfer is quenched by rapid relaxation of the metal atom. In one case, analysis of satellite patterns in a set of 1 H, 15 N, 1 H, 195 Pt and 1 H, 13 C correlation spectra allowed a positive sign to be determined for 1 J (Pt, 15 N). Qualitative arguments are presented to explain the observed 15 N coordination shifts in complexes with different azine ligands in terms of azine–M dative bond formation and L n M–azine back‐donation. Copyright © 2004 John Wiley & Sons, Ltd.