SOLVENT-INDUCED AGGREGATION THROUGH PT…PT INTERACTIONS: THEORETICAL STUDY OF THE LUMINESCENT ORGANOPLATINUM(II) TERPYRIDYL COMPLEXES

We report a theoretical study of both the structural and optical properties of phosphorescent square-planar Pt(II) terpyridine complexes, namely [Pt(tpy)(CºC-CºCH)]OTf that exhibit, at high concentrations, an additional emission band at longer wavelength. The complex [Pt(tpy)(CºC-CºCH)]OTf 1 has been found to exist in two forms, a dark-green and a red form; both of which have been structurally characterized and shown to exhibit different crystal-packing arrangements. The geometry optimizations of both the ground state of the considered monomer and different possible trimers have been performed in solution using several density functional theory (DFT) functionals. The UV−visible absorption spectra of the complexes are well rationalized using a vertical time-dependent DFT (TD-DFT) protocol relying on a global hybrid exchange−correlation functional. Le changement remarquable des caractéristiques d'absorption UV-vis induites par des changements dans la composition du solvant peut être considéré comme un type spécial de solvatochromisme

Synthesis, photophysics and molecular structures of luminescent 2,5-bis(phenylethynyl)thiophenes (BPETs)

International audienceThe Sonogashira cross-coupling of two equivalents of para-substituted ethynylbenzenes with 2,5-diiodothiophene provides a simple synthetic route for the preparation of 2,5-bis(para-R-phenylethynyl)thiophenes (R = H, Me, OMe, CF3, NMe2, NO2, CN and CO2Me) (1a-h). Likewise, 2,5-bis(pentafluorophenylethynyl)thiophene (2) was prepared by the coupling of 2,5-diiodothiophene with pentafluorophenylacetylene. All compounds were characterised by NMR, IR, Raman and mass spectroscopy, elemental analysis, and their absorption and emission spectra, quantum yields and lifetimes were also measured. The spectroscopic studies of 1a-h and 2 show that both electron donating and electron withdrawing para-subsituents on the phenyl rings shift the absorption and emission maxima to lower energies, but that acceptors are more efficient in this regard. The short singlet lifetimes and modest fluorescence quantum yields (ca. 0.2-0.3) observed are characteristic of rapid intersystem crossing. The single-crystal structures of 2,5-bis(phenylethynyl)thiophene, 2,5-bis(para-carbomethoxyphenylethynyl)thiophene, 2,5-bis(para-methylphenylethynyl)thiophene and 2,5-bis(pentafluorophenylethynyl)thiophene were determined by X-ray diffraction at 120 K. DFT calculations show that the all-planar form of the compounds is the lowest in energy, although rotation of the phenyl groups about the C[triple bond, length as m-dash]C bond is facile and TD-DFT calculations suggest that, similar to 1,4-bis(phenylethynyl)benzene analogues, the absorption spectra in solution arise from a variety of rotational conformations. Frequency calculations confirm the assignments of the compounds' IR and Raman spectra

Migration of a phenyl group from co-ordinated CH(2)(PPh(2))(2) to an acetylide on an Ru(3) cluster: crystal structure of [Ru(3)(mu-H)(mu3-PPhCH(2)PPh(2))(mu(3)-PhC(2)But)(CO)(6)]

Thermolysis (refluxing toluene, 60 h) of [Ru3(µ-H)(µ3-C2But)(µ-dppm)(CO)7] resulted in phenyl transfer from co-ordinated dppm to the µ3-acetylide to give [Ru3(µ-H)(µ3-PPhCH2PPh2)(µ3-PhC2But)(CO)6] in 41% yield, fully characterised by X-ray determinations of thf and CH2Cl2 monosolvates. The alkyne is co-ordinated to the Ru3 cluster such that the C(1)–C(2) vector forms an angle of 23° with the Ru(1)–Ru(2) vector. This distortion brings two C atoms of the alkyne Ph group close to Ru(2). Density functional and extended Hückel calculations carried out on the new compound indicated that the unusual co-ordination of the alkyne ligand can be attributed to the stereoelectronic asymmetry of the metallic fragment.Michael I. Bruce, Paul A. Humphrey, Brian W. Skelton, Allan H. White, Karine Costuas and Jean-François Hale

Oxidation chemistry of metal-bonded C4 chains: a combined chemical, spectroelectrochemical, and computational study

Copyright © 2000 American Chemical SocietyMichael I. Bruce, Paul J. Low, Karine Costuas, Jean-François Halet, Stephen P. Best, and Graham A. Heat

A multifunctional organometallic switch with carbon-rich ruthenium and diarylethene units

International audienc

Luminescent heterometallic branched alkynyl complexes of rhenium(I)-palladium(II): Potential building blocks for heterometallic metallodendrimers

The photophysical and electrochemical behavior of a novel series of luminescent rhenium(I) complexes bearing a trialkynyl ligand, [1,3-(HC≡C)2-5-{(N∧N)(CO)3ReC≡C}C 6H3] (N∧N = tBu2bpy 1, Me 2bpy 2, bpy 3), and their heterometallic branched complexes, [1,3-{Cl(PEt3)2PdC≡C}2-5-{(Nand;N)(CO) 3ReC≡C}C6H3] (N∧N = Me2bpy 4, bpy 5), have been studied; the X-ray crystal structures of 2 and 5 have been determined. Density functional theory calculations have also been carried out in order to probe the bonding in these compounds.link_to_subscribed_fulltex

Some ruthenium complexes containing cyanocarbon ligands: syntheses, structures and extent of electronic communication in binuclear systems

The preparation of several ruthenium complexes containing cyanocarbon anions is reported. Deprotonation (KOBut) of [Ru(NCCH2CN)(PPh3)2Cp]PF6 (1) gives Ru{N=C=CH(CN)}(PPh3)2Cp (2), which adds a second [Ru(PPh3)2Cp]+ unit to give [{Ru(PPh3)2Cp}2(μ-NCCHCN)]+ (3). Attempted deprotonation of the latter to give the μ-NCCCN complex was unsuccessful. Similar chemistry with tricyanomethanide anion gives Ru{N=C=C(CN)2}(PPh3)2Cp (4) and [{Ru(PPh3)2Cp}2{μ-NCC(CN)CN}]PF6 (5), and with pentacyanopropenide, Ru{N=C=C(CN)C(CN)C(CN)2}(PPh3)2Cp (6) and [{Ru(PPh3)2Cp}2{μ-NCC(CN)C(CN)C(CN)CN}]PF6 (7). The Ru(dppe)Cp* analogues of 6 and 7 (8 and 9) were also prepared. Thermolysis of 6 (refluxing toluene, 12 h) results in loss of PPh3 and formation of the binuclear cyclic complex {Ru(PPh3)Cp[μ-N=C={C(CN)=C(CN)2}CN]}2 (10). The solid-state structures of 2–4 and 8–10 have been determined and the nature of the isomers shown to be present in solutions of the binuclear cations 7 and 9 by NMR studies has been probed using Hartree–Fock and density functional theory

New charge transfer salts based on bis(ethylenedithio)tetrathiafulvalene (ET) and ferro or antiferromagnetic oxalato-bridged dinuclear anions: Syntheses, structures and magnetism of ET5[MM′(C2O4)(NCS)8] with MM′ = CrIIIFeIII, CrIIICrIII

cited By 19International audienceElectrochemical combination of the magnetic dinuclear anion [MM′(C2O4)(NCS)8]4- (MM′ = CrIIICrIII, CrIIIFeIII) with the ET organic π-donor (ET = BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) gives rise to two new isostructural molecular hybrid salts ET5[MM′(C2O4)(NCS)8], with MM′ = CrCr (1), CrFe (2). The molecular structure of compound 1 has been determined by single crystal X-ray diffraction. The particular arrangement of the organic units consists of an unprecedented two-dimensional organic sublattice nearly similar to that observed in κ-phase structures. For both compounds, the magnetic susceptibility measurements indicate (i) the ET radicals do not contribute to the magnetic moment probably due to the presence of strong antiferromagnetic interaction between them, and (ii) in the anion, the magnetic coupling is antiferromagnetic for 1 (J = -3.65 cm-1) and ferromagnetic for 2 (J = 1.14 cm-1, J being the parameter of the exchange Hamiltonian H = -2JS1S2). The field dependence of the magnetization of compound 2 at 2.0 K gives further evidence of the S = 4 ground-state arising from the interaction between S = 3/2 Cr(III) and S = 5/2 Fe(III). EPR measurements confirm the nature of the magnetic interactions and the absence of any contribution from the organic part, as observed from the static magnetic measurement. Conductivity measurements and electronic band structure calculations show that both salts are semiconductors with low activation energies