Selective one-pot syntheses of Pt(II)-Cu(I) heterobimetallic complexes of 4,5-diazafluorenide derivatives.

We report both the stepwise and one-pot syntheses of Pt(II)-Cu(I) hetero-dinuclear complexes using 4,5-diazafluorenide (L(-)) and 9-(2-(diphenylphosphino)ethyl)-4,5-diazafluorenide (L(p)(-)) as binucleating ligands. In the case of L(p)(-), the tethered phosphine arm helps anchor the Pt(II) centre onto the carbon site of the diazafluorenide and the Cu(I) centre is bound to the N,N-chelate site. In the case of L(-), the Cu(I) centre is bound to the carbon site of diazafluorenide and the Pt(II) centre is coordinated to the N,N-chelate site.

Syntheses, structures, and luminescent properties of dipyridylamine-functionalized anthracene and its complexes.

A novel multidentate ligand with 2,2'-dipyridylamine functionalities, 1,8-bis[4-(2,2'-dipyridylamino)phenylacetylenyl]anthracene (1), has been synthesized through a double Sonogashira coupling reaction and characterized by NMR spectroscopic, elemental, and X-ray diffraction analyses. Compound 1 can bind to either one metal center as a tetradentate ligand or two metal centers as a double-bidentate ligand. In the double-bidentate mode, the distance between the two metal centers may vary significantly. Compound 1 displays bright blue luminescence in the solid state and in solution with a quantum efficiency of 64% relative to 9,10-diphenylanthracene. While the dirhodium complex of 1 shows no luminescence, the two zinc complexes of 1 display blue luminescence with quantum efficiencies slightly lower than that of 1. Organic light-emitting devices (OLEDs) using 1 as the emitter show a maximum current efficiency of 7 cd/A.

Interconversion between the enantiomers of chiral five-coordinate Me3Pt(IV) complexes.

The dinuclear Me(2)Pt(II) complexes of 3,4-bis(quinolin-8-yl)thiophene (1a), 3,4-bis(6 trifluoromethoxyquinolin-8-yl)thiophene (1b), and 3,4-bis(2-methylquinolin-8-yl)thiophene (1c) react with MeOTf (OTf = trifluoromethanesulfonate) to afford the corresponding chiral mononuclear five-coordinate Me(3)Pt(IV) complexes [PtMe(3)(1a)]OTf (3a), [PtMe(3)(1b)]OTf (3b), and [PtMe(3)(1c)]OTf (3c), respectively. [PtMe(3)(1c)]BAr(F)(4) (3d) (where BAr(F)(4) = [B{C(6)H(3)-3,5-(CF(3))(2)}(4)]) has also been synthesized for structural study. While 3a appears to be symmetric in solution and asymmetric in solid state, 3c and 3d are asymmetric in both solution and solid state. The chirality originates from interligand repulsion, rather than any unsymmetrical ligand. Variable-temperature NMR and computational studies suggest a ligand-twisting isomerization pathway for the interconversion of the enantiomers, rather than the rotational exchange of three CH(3) ligands on the metal center.

Ester hydrogenation catalyzed by Ru-CNN pincer complexes.

We report new Ru-CNN pincer catalysts for ester hydrogenation under mild conditions.

Platinum complexes of eta2-thiophenes.

Two novel ligands, 3,4-bis(quinolin-8-yl)thiophene and 3,4-bis[6-(trifluoromethoxyl)quinolin-8-yl]thiophene, and their corresponding diplatinum complexes have been synthesized and fully characterized. These two complexes feature the inverse sandwich structures and the eta(2)-C,C thiophenes on platinum centers.

Reductive dearomatization of a substituted benzene triggered by a strong oxidant.

Two new dinuclear platinum complexes Pt(2)Ph(4)L(Et) (1a) and Pt(2)Ph(4)L(F) (1b) (where L(Et) is 1,2,4,5-tetrakis(6-ethylquinolin-8-yl)benzene and L(F) is 1,2,4,5-tetrakis(6-trifluoromethoxylquinolin-8-yl)benzene) were synthesized and characterized. Triggered by an oxidant NCS, 1a and 1b displayed interesting reactivity of reductive dearomatization of the central phenyl rings of L(Et) and L(F) ligands respectively. The preliminary radical scavenger test gave some mechanistic insights.