Di-metallated platinum carbonyl complexes: platinum-platinum interactions in the solid state

The reaction of a diphenylpyridine with one equivalent of potassium tetrachloroplatinate in ethanoic acid yields a cyclometallated species which can be induced to undergo a second cyclometallation to give a C∧N∧C tridentate species. Carbonyl derivatives of two such compounds have been structurally characterised. The X-ray structure of the complex [2,6-(4′-C6H13OC6H3)2C5H3NPt(CO)], (1), obtained using 2,6-bis(4′-hexyloxyphenyl)pyridine, has no unusual features. In contrast, the structure of the complex [2,6-(C6H4)2-4-(4′-C8H17OC6H5)C5H2NPt(CO)], (2), which results when using 4-(4′-octyloxy-phenyl)-2,6-diphenylpyridine, has close intermolecular contacts, with a Pt–Pt “bond” of 3.243(1) Å holding the molecules together as dimers. Compound 2 also exists in another form in the solid state, a form that does not appear to contain Pt–Pt bonds