The lower excited electronic states of singly and doubly reduced 2,2′-bipyridine
TL;DR: In this paper, the electronic spectra of bipy− and bipy2− anions (bipy = 2,2′-bipyridine) have been measured between 5000 and 50 000 cm−1.
About: This article is published in Chemical Physics Letters.The article was published on 1970-03-01. It has received 85 citations till now. The article focuses on the topics: 2,2'-Bipyridine.
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TL;DR: A survey of anion radical ligands and their complexes can be found in this article, where anion radicals and their properties are discussed as well as the properties of the ligands.
331 citations
TL;DR: In this article, transient absorption anisotropy measurements indicate that after one picosecond the molecule has no memory of which bipyridine was initially photoselected, which suggests an ultrafast interligand randomization of the MLCT state.
Abstract: It is known that the relaxed excited state of [Ru(bpy)3]2+ is best described as a metal to ligand charge transfer (MLCT) state having one formally reduced bipyridine and two neutral. Previous reports have suggested [Malone, R. et al. J. Chem. Phys. 1991, 95, 8970] that the electron “hops” from ligand to ligand in the MLCT state with a time constant of about 50 ps in acetonitrile. However, we have done transient absorption anisotropy measurements indicating that already after one picosecond the molecule has no memory of which bipyridine was initially photoselected, which suggests an ultrafast interligand randomization of the MLCT state.
174 citations
TL;DR: In this article, it was shown that the mixed-valence dimer of [Pt(tpy)Cl] can be reduced in 0.1 M TBAH/DMF with a constant of 8(1) × 10 and 10(4] × 10 M^(-1), respectively.
Abstract: [Pt(tpy)Cl]^+ (tpy is 2,2‘:6‘,2‘‘-terpyridine) undergoes reversible one-electron reductions in 0.1 M TBAH/DMF (TBAH is tetrabutylammonium hexafluorophosphate) at E° ‘_(+/0) = −0.74 V and E° ‘_(0/-) = −1.30 V (vs AgCl (1.0 M KCl)/Ag). The first reduction couple is substantially positive of those observed for other M(II)−tpy complexes (for example, E° ‘_(0/-) = −1.36 V for [Zn(tpy)Cl_2]), a finding that suggests there is coupling between the empty 6p_z orbital of square planar Pt(II) and the π* orbital of tpy, stabilizing the (π*)^1 radical state. The dimerization constants of both [Pt(tpy)Cl]^+ and [Pt(tpy)Cl] in 0.1 M TBAH/DMF were determined spectroelectrochemically and found to be 8(1) × 10 and 10(4) × 10 M^(-1), respectively. On the basis of variable-concentration studies, a species observed at an intermediate level of reduction is formulated as the mixed-valence dimer [(Pt(tpy)Cl)_2]^+, with K_(mix) = [(Pt(tpy)Cl)_2^+]/([Pt(tpy)Cl^+][Pt(tpy)Cl]) = 18(4) × 10 M^(-1). Analysis of variable-temperature EPR spectra indicates that the first reduction is ligand-centered (^2B_2) with substantial contributions from Pt(II) 5d_(yz) (4−6%) and 6p_z (3−4%). The second reduction is tentatively assigned as metal-centered; 5d_(x^2 - y^2) is the likely acceptor orbital.
169 citations
TL;DR: In this article, an electron exchange model for spin coupling between Yb(III), with electron configuration 4f13, and the single unpaired electron in the bipyridyl radical anion was presented, based on comparison with the iodide salt [(Me5C5)2YbIII(bipy0)]+[I]-.
165 citations
TL;DR: In this paper, the background of low-energy absorptivity is provided, together with examples from the inorganic and organometallic coordination chemistry of Mo, Mn, Fe, Ru, Os, Rh, Ir, Pt and Cu.
146 citations
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TL;DR: In this article, the theory of electronic spectra and electronic structure was further developed and applied to ethylene, butadiene, benzene, pyridine, pyrimidine, pyrazine, and s-triazine.
Abstract: The theory of electronic spectra and electronic structure, the elucidation of which was begun in the first paper of this series, is further developed and applied to ethylene, butadiene, benzene, pyridine, pyrimidine, pyrazine, and s‐triazine.A realistic and consistent LCAO‐MO π‐electron theory should allow the σ‐electrons to adjust themselves to the instantaneous positions of the mobile π‐electrons. This is accomplished in the theory by assignment of empirical values to the Coulomb electronic repulsion integrals and Coulomb penetration integrals which enter the formulas, these values being obtained in a prescribed way from valence state ionization potentials and electron affinities of atoms. Use of the empirical values in the molecular orbital theory reduces the magnitude of computed singlet‐triplet splittings and the effects of configuration interaction without complicating the mathematics. From the valence‐bond point of view, ionic structures may be said to be enhanced.The applications to hydrocarbons a...
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02 Sep 2010
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TL;DR: In this article, the electronic spectra of the mononegative ions of naphthalene, anthracene, tetracene and phenanthrene, pyrene, perylene, biphenyl, terphenyl and quater-phenyl have been qualitatively interpreted with the aid of L.C.O. calculations including configuration interaction.
Abstract: The electronic spectra of the mononegative ions of naphthalene, anthracene, tetracene, phenanthrene, pyrene, perylene, biphenyl, terphenyl and quater-phenyl have been qualitatively interpreted with the aid of L.C.A.O.-M.O. calculations including configuration interaction. The calculated dipole strengths are on the average about twice to three times as high as the experimental values. In a relative sense, however, the agreement between observed and calculated dipole strengths is satisfactory.
40 citations