Synthesis of asymmetric supramolecular compounds using a Ni(0) catalysed homo-coupling approach

The synthesis and characterisation of a series of dinuclear ruthenium and osmium polypyridyl metal complexes based on the bridging ligands [5-(5'-bipyridin-2',2 ''-yl)-3-(pyridin-2-yl)]-1,2,4-triazole (Hpytr-bipy), 2,2 ''-bis(pyridin-2 '' yl)-5,5 ''-bis(pyridin-3 ''-yl) (bipy-bipy) and 5,5'-bis(pyridin-2 ''-yl)-3,3'-bis(1,2,4-triazole) (Hpytr-Hpytr) are reported. The dinuclear complexes have been synthesised via a Ni(0) catalysed cross-coupling reaction from brominated precursors. With this approach a mixture of three products is obtained, which are separated by chromatographic methods. The compounds obtained are characterised by elemental analysis, H-1 NMR, absorption and emission spectroscopy. The synthetic approach developed offers a new route to asymmetric multinuclear supramolecular structures that is complimentary to the complexes as ligands/complexes as metal approaches.