Synthesis and Characterization of Optically Active and Racemic Forms of Cyclometalated Rh(III) Complexes. An Experimental and Theoretical Emission Study

Abstract

The optically active cyclometalated Rh(III) complexes, delta[Rh(thpy4,5p(R,R)py)(2)TAP]Cl, lambda[Rh(thpy4,5p(S,S)py)(2)TAP]Cl, and delta[Rh(phpy4,5p(R,R)py)(2)TAP]Cl (where TAP = 1,4,5,8-tetraazaphenanthrene, thpy4,5p(R,R)py = (8R,10R)-2-(2'-thienyl)-4,5-pinenopyridine and phpy4,5p(R,R)py = (8R,10R)-2-(2'-phenyl)-4,5-pinenopyridine) have been prepared and characterized. Their photophysics has been examined in parallel with that of rac[Rh(thpy)(2)TAP]Cl and rac[Rh(phpy)(2)TAP]Cl. Their behaviors have been rationalized from results of TD-DFT calculations. The complexes with thienylpyridine (thpy) as cyclometalating ligands exhibit (3)CT (from thpy to TAP) and (3)LC(pi-pi) (centered on thpy) emissions in a solvent matrix at 77 K and one (3)CT luminescence at room temperature. In contrast, with phenylpyridine (phpy), the complexes show only one (3)CT emission (from phpy to TAP) at both temperatures.

Density Functional Methods for Excited States: Equilibrium Structure and Electronic Spectra

“…TDDFT calculations for neutral dithiolene complexes of nickel, palladium, and platinum have explained the uncommon properties of these compounds, especially the presence of an exceedingly strong absorption in the near IR region [269]. Other studies investigate the photophysics and the luminescence behavior of cyclometalated complexes of rhodium [270] and iridium [271].…”

Direct enantiomeric separations of tris(2‐phenylpyridine) iridium (III) complexes on polysaccharide derivative‐based chiral stationary phases

“…Recently, the interest in enantiomerically pure metallic compounds has rapidly increased, and studies on the chirality of octahedral complexes (fac-D-and fac-K-isomers) have been attractive in several research areas, such as bioinorganic and supramolecular chemistry and catalysis [8][9][10][11]. The increasing need for obtaining optically pure metallic complexes are essential driving forces in the search for a direct method for the resolution of racemic octahedral complexes.…”

Photophysical and electrochemical properties of new ortho-metalated complexes of rhodium(iii) containing 2,2′-dipyridylketone and 2,2′-dipyridylamine. An experimental and theoretical study

“…4 In the last two decades, the replacement of N,N-donor ligands such as 2,2 -bipyridine (bpy) and 1,10-phenanthroline (phen) with N,C-donor ligands such as 2-phenylpyridine (ppy) and benzo[h]quinoline (bzq) has been of particular interest. 5- 13 The spectroscopic results for these materials indicate that the orthometalation would result in higher-energy d-d* transitions, which can be ascribed to the strong r-donor/p-acceptor abilities of these ligands. Consequently, low-energy metal-to-ligand charge-transfer (MLCT) emissions have been observed as d* orbitals are higher in energy than the ligand lowest unoccupied molecular orbital (LUMO).…”