Coordinating Tectons: Bipyridyl Terminated Allenylidene Complexes

• Published in: Organometallics 2008-04, Vol.27 (8), p.1716-1726
• Main Authors: Cifuentes, Marie P, Humphrey, Mark G, Koutsantonis, George A, Lengkeek, Nigel A, Petrie, Simon, Sanford, Vanessa, Schauer, Phil A, Skelton, Brian W, Stranger, Robert, White, Allan H
• Format: Article
• Language: English
• Subjects: BIPYRIDINES; CARBON COMPLEXES; DENSITY FUNCTIONAL METHOD; ELECTROCHEMISTRY; ELECTRONIC STRUCTURE; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LIGANDS; METALS; SYNTHESIS; VALENCE
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om700824g

A series of complexes with π-conjugated carbon chains terminated by bipyridyl moieties has been prepared. These allenylidene complexes were derived from 9-hydroxy-9-ethynyl-4,5-diazafluorene, the preparation of which is reported; the new allenylidene complexes are highly colored with the cumulated carbon chain terminating in a bipyridyl unit providing a site for further coordination. The synthesis, characterization, and X-ray structure determination of trans-[MCl(P∩P)2CC(4,5-diazafluoren-9-yl)]PF6 (M = Ru, P∩P = bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,2-bis(dimethylphosphino)ethane (dmpe); M = Os, P∩P = dppm) are described. The effect of the variation in metal and ligand on electronic and electrochemical characteristics of these complexes has been investigated by using UV–vis, solution electrochemistry, and a combination of these techniques in spectroelectrochemical experiments. DFT calculations have been performed on trans-[RuCl(P∩P)2CC(4,5-diazafluoren-9-yl)] q (P∩P = dppm, bis(dimethylphosphino)methane (dmpm); q = −1, 0, +1, +2) and subsequently solvent-corrected calculations with use of COSMO were also undertaken to examine the nature of electronic transitions in various oxidation states.