Cyclometalation : 2,6-diphenylpyridine complexes of platinum
This thesis describes the synthesis and characterisation of novel cycloplatinated 2,6- diphenylpyridine complexes and an interesting platinum carbene complex formed by an unusual intermolecular C-H activation. 2,6-Diphenylpyridine, 2,6-bis(4'-alkoxyphenyl)pyridines, 4-(4-octyloxyphenyl)-2,6- diphenylpyridine and 2,4,6-tris-(4-alkoxyphenyl)-[1,3,5]triazine have all been mono- cycloplatinated to from chloride bridged dimers. These dimers have been cleaved with various ligands including trimethylphosphine, dimethylsulfoxide and carbon monoxide. The synthesis and characterisation of the cyclometalated products of 2- phenylpyridine, and subsequent oxidation to a platinum(IV) complex has been described. A novel high yield synthetic route to the di-cycloplatination of C"N"C type ligands involving a C-H activation induced by water has also been reported. The synthesis of di- cycloplatinated 2,6-diphenylpyridine, 2,6-bis( 4'-alkoxyphenyl)pyridines and 4-(4'- octyloxyphenyl)-2,6-diphenylpyridine ligands has been recorded. The lability of the dimethylsulfoxide ligand used in the di-cyclometalation reaction is demonstrated by its substitution with trimethylphosphine, carbon monoxide and the stilbazole ligand. Thermal analyses of all the ligands and cyclometalated products have been recorded. The mesogenic behaviour of four materials has been described and discussed. This report also includes a synthetic route to a platinum carbene dimer formed from a 2,6-bis(2',4'-alkoxyphenyl)pyridine ligand.