MULTINUCLEAR NMR-STUDIES OF PALLADIUM(II) DIHALIDE COMPLEXES OF DIBUTYL LPHA-[4-(PHENYLDIAZENYL)ANILINO]BENZYL)PHOSPHONATE

The H-1, C-13, N-15 and P-31 NMR studies of two types of palladium(II) dihalide complexes of dibutyl lpha-[4-(phenyldiazenyl)anilino]benzyl} phosphonate (L) are reported: those with the monodentate trans-bonded ligands through the azo nitrogen, trans-Pd(L)(2)X-2 (X = Cl, Br), and a cyclopalladated binuclear complex in which chloride ions bridge two metal centers, [Pd(L-H)(mu-Cl)](2). The N-15-enriched organophosphorus compound and its palladium(II) complexes were also prepared to enable unambiguous determination of the nitrogen ligation site by N-15 NMR. The NMR analysis was accomplished by one-and two-dimensional home-and heteronuclear experiments including H-1-H-1 COSY, long-range H-1-H-1 C OSY, NOESY, H-1-C-13 COSY, long-range H-1-C-13 COSY, HMQC and HMBC. Wi th the mononuclear complexes, the formation of isomeric species was ob served, which are interpreted as rotational isomers caused by restrict ed rotation around the metal-ligand bond.