Synthesis of dinuclear dicationic heterobridged gold(I) ring derivatives with bis(diphenylphosphines) and bihapto symmetric or asymmetric ligands containing heterocycles: P-31 NMR investigations

The reactions of [Au-2 mu-bis(diphosphine)](2+) with 1,3-asymmetric bihapto or 1,5-symmetric bihapto ligands yield the heterobridged complexes [Au-2 mu-bis(diphosphine) mu-(L'-L')](2+) (I-VIII) where the bis(diphospine) can be: dppm = bis(diphenylphosphinomethane), dppe = bis(diphenylphosphino)ethane, or dppp = bis(diphenylphosphino)propane; L'-L' can be: (1-benzyl-2-imidazolyl)diphenylphosphine, 2-mercapto-1-methylimidazole, or 1, 1'-methylenedipyrazole. The gold(I) complexes were characterized especially by P-31 NMR spectroscopy, and in two cases equilibrium reactions were also detected. Moreover, a P-31 NMR data correlation between the chemical shifts and the increase of the number of methylene groups in the bisphosphine ligands is also reported.