Dinuclear Ru/Ni, Ir/Ni, and Ir/Pt Complexes with Bridging Phenanthroline-5,6-dithiolate: Synthesis, Structure, and Electrochemical and Photophysical Behavior

Abstract

We report the synthesis and full characterization of dinuclear complexes with the bridging ligand phenanthroline-5,6-dithiolate (phendt(2-)) featuring the [Ru(bpy)2](2+) or Ir(ppy)2](+) fragment at the diimine donor center and the [Ni(dppe)](2+) or [Pt(phen)](2+) complex moiety at the dithiolate group. The molecular structures of the mononuclear complexes [(C5H5)2Ti(S,S'-phendt)] and [(ppy)2Ir{N,N'-phendt-(C2H4CN)2}](PF6) as well as the dinuclear complex [(C5H5)(PPh3)Ru(phendt)Ni(dppe)](PF6) determined by X-ray diffraction (XRD) studies are compared. Photophysical studies with mononuclear [(bpy)2Ru{phendt-(C2H4CN)2}](2+) and [(ppy)2Ir{phendt-(C2H4CN)2}](+) as well as dinuclear [(bpy)2Ru(phendt)Ni(dppe)](2+) and [(ppy)2Ir(phendt)Ni(dppe)](+) uncovered an effective luminescence quenching in the dinuclear complexes. Lifetime measurements at room temperature, steady-state measurements at low temperature, electrochemical investigations, and DFT calculations provide evidence for a very efficient energy transfer from the Ru/Ir to the Ni complex moiety with a rate constant k > 5 × 10(9) s(-1). In comparison, the [Ru]phendt[Ni] complex displays a higher quenching efficiency with reduced excited state lifetime, whereas the [Ir]phendt[Ni] complex is characterized by an unaltered lifetime of the thermally equilibrated excited state.

Stille Expands the Family: Access to 5,6‐Bis‐2‐thienyl‐Substituted Phenanthroline Under Mild Conditions for Luminescent Ruthenium Complexes

“…Conspicuously, the orientation of the thiophene rings are distributed almost equally with 54 % and 46 % for parallel and antiparallel orientations, respectively. This is in contrast with literature value for related compounds favoring the parallel orientation with 75 % Taking the less steric demand of thiophene moieties within 2 into account, the measured torsion angles of the two thiophenes with 65.31° and 67.60° with respect to the phenanthroline plane seem reasonable, which is very similar to previously reported thiophene‐substituted phenanthrolines. Interestingly, in case of even more sterically demanding dimethyl‐substituted thiophenes torsion angles lie in the same region , …”

“…Regarding the photophysical properties of phenanthroline complexes, it is well known that substitution of phenanthroline in 3,8‐ and 4,7‐positions significantly influences the photochemistry of coordination complexes as π‐orbital energies are strongly influenced , . In this context, the effects of substituents introduced at 5‐ or 5,6‐position of phenanthroline are far less explored , . This is mainly due to the demanding synthetic procedures in order to access these positions efficiently.…”

Synthesis, characterisation and ion-binding properties of oxathiacrown ethers appended to [Ru(bpy)2]2+. Selectivity towards Hg2+, Cd2+and Pb2+

“…Previously, it has been shown that substituents in the 5-and/or 6-positions have negligible effects on the wavelength of absorption. 28,29 The luminescence spectra of the complexes were recorded in CH 3 CN at room temperature with excitation at the absorption maxima (l max ) of the MLCT bands. The complexes exhibit broad emission manifolds which may be assigned as 3 MLCT phosphorescence, in the 607-611 nm region.…”

Crystal structure of cis-[1,2-bis(diphenylphosphanyl)ethene-κ2 P,P′]dichloridoplatinum(II) chloroform disolvate: a new polymorph

“…The rigid compound cis-1,2-bis(diphenylphosphanyl)ethylene (cis-dppe) has been widely exploited as a bidentate ligand for transition metals. A selection of recent examples include complexes involving iron(II) (Song et al, 2018), copper(I) (Trivedi et al, 2017), gold(I) (Yao & Yam, 2015), nickel(II) (Schallenberg et al, 2014), nickel(III) (Hwang et al, 2015), and palladium(II) and platinum(II) (Song et al, 2017;Oberhauser et al, 1998a). The phosphorus atoms of this ligand have also been modified to give the corresponding oxide, sulfide and selenide derivatives (Morse et al, 2016;Duncan & Gallagher, 1981;Colquhoun et al, 1979;Aguiar & Daigle, 1964).…”