- Luminescent piano-stool complexes incorporating 1-(4-cyanophenyl)imidazole: Synthesis, spectral, and structural studies
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Three novel luminescent piano-stool arene ruthenium complexes of general formula [(η6-arene)RuCl2(CPI)] (η6- arene = benzene, 1, p-cymene, 2, and hexamethylbenzene, 3; CPI=1-(4-cyanophenyl) imidazole were prepared. The molecular structures of 2 and 3 were determined crystallographically. Reaction of 1-3 with EPh3 (E = P, As, or Sb) and N-N donor bases such as 2,2′-bipyridine and 1,10-phenanthroline afforded cationic mononuclear complexes of general formula [(η6- arene)RuCl(CPI)(EPh3)]+ (η6-arene = C 6H6, E = P (1a), E = As (1b), E = Sb (1c); η6-arene = C10H14, E = P (2a), E = As (2b), E = Sb (2c); η6-arene = C6Me6, E = P (3a), E = As (3b), E = Sb (3c)) and [(η6-arene)Ru(N-N)(CPI)] 2+ (η6-arene = C6H6, N-N = bipy (1d), N-N = phen (1e); η6-arene = C10H14, N-N = bipy (2d), N-N = phen (2e); η6-arene = C6Me 6, N-N = bipy (3d), N-N = phen (3e)). Molecular structures of 1a and 2a were also confirmed by X-ray crystallography. Structural studies of the complexes 2, 3, 1a, and 2a supported coordination of CPI through the imidazole nitrogen and the presence of a pendant nitrile group. Structural data also revealed stabilization of crystal packing in the complexes 2, 3, and 2a by C-H...X (X = Cl, F) type inter- and intramolecular interactions and in complex 1a by π-π stacking. Moreover, neutral homonuclear bimetallic complexes 2f,g were prepared by using complex 2 as a metallo-ligand, where CPI acts as a bridge between two metal centers. Emission spectra of the mononuclear complexes [(η6-arene)RuCl2(CPI)] and its derivatives exhibited intense luminescence when excited in the metal to ligand charge-transfer band.
- Singh, Sanjay K.,Trivedi, Manoj,Chandra,Sahay, Abhaya N.,Pandey, Daya Shankar
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p. 8600 - 8608
(2008/10/09)
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