Luminescent Rhenium(I) Phenanthroline Complexes with a Benzoxazol-2-ylidene Ligand: Synthesis, Characterization, and Photophysical Study

A series of luminescent rhenium­(I) phenanthroline complexes containing benzoxazol-2-ylidene ligands with the general formula {Re­(CO)₃(phen)­[CN­(X)­C₆H₄-2-O]}⁺ and <i>cis</i>,<i>trans</i>-{Re­(CO)₂(phen)­(L)­[CN­(H)­C₆H₄-2-O]}⁺ (X = H, methyl; phen = 1,10-phenanthroline; L = PPh₃, PPh₂Me, P­(OEt)₃) have been synthesized and characterized. The X-ray crystal structures of most of the carbene complexes and some of their synthetic precursors have also been determined. A new synthetic methodology for the preparation of dicarbonyl rhenium diimine synthetic precursors with a labile acetonitrile ligand, [Re­(CO)₂(phen)­(PR₃)­(MeCN)]⁺, was developed. Photophysical study shows that these carbene complexes display a green to red ³MLLCT [dπ­(Re) → π*­(N–N)] phosphorescence at room temperature. The N-deprotonations of the benzoxazol-2-ylidene ligand in these complexes were investigated

Luminescent Rhenium(I) Phenanthroline Complexes with a Benzoxazol-2-ylidene Ligand: Synthesis, Characterization, and Photophysical Study

A series of luminescent rhenium­(I) phenanthroline complexes containing benzoxazol-2-ylidene ligands with the general formula {Re­(CO)₃(phen)­[CN­(X)­C₆H₄-2-O]}⁺ and <i>cis</i>,<i>trans</i>-{Re­(CO)₂(phen)­(L)­[CN­(H)­C₆H₄-2-O]}⁺ (X = H, methyl; phen = 1,10-phenanthroline; L = PPh₃, PPh₂Me, P­(OEt)₃) have been synthesized and characterized. The X-ray crystal structures of most of the carbene complexes and some of their synthetic precursors have also been determined. A new synthetic methodology for the preparation of dicarbonyl rhenium diimine synthetic precursors with a labile acetonitrile ligand, [Re­(CO)₂(phen)­(PR₃)­(MeCN)]⁺, was developed. Photophysical study shows that these carbene complexes display a green to red ³MLLCT [dπ­(Re) → π*­(N–N)] phosphorescence at room temperature. The N-deprotonations of the benzoxazol-2-ylidene ligand in these complexes were investigated

Synthesis, Characterization, and Photophysical Study of Luminescent Rhenium(I) Diimine Complexes with Various Types of N‑Heterocyclic Carbene Ligands

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 ¹H and ¹³C NMR and IR spectroscopy, mass spectrometry, and elemental analysis. One of the precursor complexes <i>fac</i>-{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 <i>trans</i> ligand. All these complexes displayed ³MLCT [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

Luminescent Rhenium(I) Pyridyldiaminocarbene Complexes: Photophysics, Anion-Binding, and CO₂‑Capturing Properties

A series of luminescent isocyanorhenium­(I) complexes with chelating acyclic diaminocarbene ligands (N^C) has been synthesized and characterized. Two of these carbene complexes have also been structurally characterized by X-ray crystallography. These complexes show blue-to-red phosphorescence, with the emission maxima not only considerably varied with a change in the number of ancillary isocyanide ligands but also extremely sensitive to the electronic and steric nature of the substituents on the acyclic diaminocarbene ligand. A detailed study with the support of density functional theory calculations revealed that the lowest-energy absorption and phosphorescence of these complexes in a degassed CH₂Cl₂ solution are derived from the predominantly metal-to-ligand charge-transfer [dπ­(Re) → π*­(N^C)] excited state. The unprecedented anion-binding and CO₂-capturing properties of the acyclic diaminocarbene have also been described

Luminescent Rhenium(I) Pyridyldiaminocarbene Complexes: Photophysics, Anion-Binding, and CO₂‑Capturing Properties

A series of luminescent isocyanorhenium­(I) complexes with chelating acyclic diaminocarbene ligands (N^C) has been synthesized and characterized. Two of these carbene complexes have also been structurally characterized by X-ray crystallography. These complexes show blue-to-red phosphorescence, with the emission maxima not only considerably varied with a change in the number of ancillary isocyanide ligands but also extremely sensitive to the electronic and steric nature of the substituents on the acyclic diaminocarbene ligand. A detailed study with the support of density functional theory calculations revealed that the lowest-energy absorption and phosphorescence of these complexes in a degassed CH₂Cl₂ solution are derived from the predominantly metal-to-ligand charge-transfer [dπ­(Re) → π*­(N^C)] excited state. The unprecedented anion-binding and CO₂-capturing properties of the acyclic diaminocarbene have also been described