title: Synthesis, characterization, and photophysical study of luminescent rhenium(I) diimine complexes with various types of N-heterocyclic carbene ligands.
abstract: A series of luminescent Re(I) diimine complexes with various types of N-heterocyclic carbene (NHC) ligands has been synthesized through the reaction between isocyano Re(I) diimine complexes with different nucleophiles. These Re(I) NHC complexes were characterized by (1)H and (13)C NMR and IR spectroscopy, mass spectrometry, and elemental analysis. One of the precursor complexes fac-{Re(CO)3[CN(H)C6H4-2-O]2Br} and five of the Re(I) diimine complexes with different types of NHC ligands were also structurally characterized by X-ray crystallography. In the preparation of these Re(I) NHC complexes, it is found that the reactivity of the isocyanide ligands in the synthetic complex precursors is significantly affected by the electronic nature of the trans ligand. All these complexes displayed (3)MLCT [dπ(Re) → π*(N-N)] phosphorescence in degassed CH2Cl2 and CH3CN solutions at room temperature. Through the study of the photophysical and electrochemical properties of these Re(I) NHC complexes, the electronic properties of different types of NHC ligands were investigated.
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China.
authors.forename: Chi-On
authors.initials: CO
authors.lastname: Ng
authors.forename: Shek-Man
authors.initials: SM
authors.lastname: Yiu
authors.forename: Chi-Chiu
authors.initials: CC
authors.lastname: Ko