Pressure effects on the photophysical properties of the platinum(II) dimer Pt2(POP)44- (POP = .mu.-.eta.2-H2P2O52-) and related d8-d8 dinuclear complexes in solution

Fetterolf, Monty L.; Friedman, Alan E.; Yang, Yun Yen; Offen, H. W.; Ford, Peter C.

doi:10.1021/j100324a014

Cited by 21 publications

(8 citation statements)

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“…Quenching Rate Constants. In a thoroughly deaerated aqueous solution with no quencher, [Pt 2 (pop) 4 ] 4- showed an emission decay lifetime of 9.7 μs, in good agreement with the literature ,, value. The lifetime was shortened to 8−9 μs in acidic media, but on addition of Cl - , no change was observed within the experimental error of ±0.1 μs.…”

Section: Resultssupporting

confidence: 88%

Salt and Specific Cation Effects in the Quenching of Triplet State Tetrakis(μ-pyrophosphite-P,P‘)diplatinate(II) by Acidopentacyanocobaltate(III) Anions

1997

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In the presence of moderate to high concentrations of electrolytes, the emission of *[Pt2(pop)4]4- (where pop = μ-pyrophosphite-P,P‘) is quenched by the complexes [Co(CN)5X]3- (where X = N3 -, I-, Br-, Cl-, but not CN-). The salt effects on the emission decay lifetime quenching rate constants between these anionic species have been studied in the presence of MCl, M‘Cl2, or R n NH4 - n Cl (where M, M‘, and R represent alkali, alkaline earth metals, and alkyl respectively, n = 0−3) and K n X (X = Cl-, Br-, NO3 -, SO4 2-, [Co(CN)6]3-, n = 1−3). At 0.5 M cation concentration, second-order quenching rate constants, k q, are in the “nearly diffusion-controlled” range, 107−109 L mol-1 s-1, and k q decreases by an order of magnitude across the series of quenchers [Co(CN)5I]3- > [Co(CN)5N3]3- > [Co(CN)5Br]3- > [Co(CN)5Cl]3-. On the basis of a detailed study of [Co(CN)5I]3-, the quenching efficiency increases with background electrolyte concentration and the measured rate constants are in good agreement with predictions based on the Debye−Smoluchowski and Debye−Eigen equations for diffusion-controlled formation and dissociation in ionic solution of an encounter pair, together with a rate constant of 1.2 × 109 s-1 for the quenching step. However, the analysis provides further evidence for the Olson−Simonson effect; that is, in the presence of multivalent electrolyte ions, the salt effects are determined by the counterion concentration, here the cation, rather than by the ionic strength. Specific cation effects are observed such that the quenching rate constants increase in the following sequences: Li+ < Na+ < K+ < Cs+; Mg2+ < Ca2+ < Sr2+ < Ba2+; NH4 + < MeNH3 + < Me2NH2 + < Me3NH+; Et3NH+ < Et2NH2 + < EtNH3 +; n-PrNH3 + < EtNH3 + < MeNH3 +. For the alkali or alkaline-earth cations the large effects seen require participation of the cation in the transition state for the quenching step; the alkylammonium cations are also effective in this role, but the small differences in their efficiencies can be rationalized in terms of their effects on water structure.

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Section: Resultssupporting

confidence: 88%

Salt and Specific Cation Effects in the Quenching of Triplet State Tetrakis(μ-pyrophosphite-P,P‘)diplatinate(II) by Acidopentacyanocobaltate(III) Anions

1997

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“…Stern − Volmer Quenching of 3 Pt 2 (pop) 4 4- by Ni(II) Complexes. In a thoroughly degassed solution, and in the absence of any quencher, the lifetime of a fresh solution of a fresh sample of Pt 2 (pop) 4 4- was found to be about 9 μs, which is in good agreement with literature. − The addition to 3.0 mL of Pt 2 (pop) 4 4- solution of several successive 5−20 μL aliquots of Ni(II)-complex (∼ 1 × 10 -3 M in 0.01 M HClO 4 ) was found to cause a steady decrease in the measured lifetime. Stern−Volmer analysis of the lifetime data gave linear plots which provided values for the second-order rate constants, k q , for the quenching of the excited state of Pt 2 (pop) 4 4- by each of the ten Ni(II) complexes.…”

Section: Resultssupporting

confidence: 87%

Quenching of Triplet State Tetrakis(μ-pyrophosphito-PP‘)diplatinate(II) by Nickel(II) Macrocyclic and Tris-diimine Complexes

1999

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The excited state of tetrakis(&mgr;-pyrophosphito-PP')diplatinate(II), Pt(2)(pop)(4)(4)(-), has been shown to be reductively quenched by a series of Ni(II) complexes. Steady-state photolysis of Pt(2)(pop)(4)(4)(-) in the presence of Ni(cyclam)(2+) and SO(4)(2)(-) ions was followed by absorption spectroscopy and showed the production of the Ni(III) complex with low efficiency. The Ni(III) yield was enhanced in the presence of oxygen presumably because of scavenging of Pt(2)(pop)(4)(5)(-) from the solvent-caged {Pt(2)(II,I).Ni(III)} primary product pair resulting from electron transfer. Cage escape yields of 0.028 in N(2) saturated solution and 0.054 in aerated solutions were estimated from the data. For a series of complexes with decreasing redox potential, the rate constants for their (3)Pt(2)(pop)(4)(4)(-) phosphorescence lifetime quenching decreased with driving force DeltaG, consistent with Rehm-Weller behavior and leading to a reorganization energy of approximately 60 kJ mol(-)(1). The diffusional rate constant calculated from the Debye-Smoluchowski equation was 1.6 x 10(10) M(-)(1) s(-)(1), in excellent agreement with the observed value of 1.6 x 10(10) M(-)(1) s(-)(1) based on the Rehm-Weller equation. The transmission factor for the electron transfer was estimated at 10(-)(4), in the weakly adiabatic region. Although the Rehm-Weller treatment has been used successfully in reactions involving mainly uncharged organic reactants, in this investigation it leads to an unrealistic ratio for the rate constants for the diffusive separation of the charged reactants and products. An alternative interpretation of the results based on an approach by Meyer and Nagle removes this problem and the observed linear dependence of ln k(q) on the square root of E degrees (Ni(II)/Ni(III)) in the endergonic region shows that the dominant back electron transfer produces ground-state species. The analysis also leads to an estimate of the (3)Pt(2)(pop)(4)(4)(-)/Pt(2)(pop)(4)(5)(-) potential of 1.29 +/- 0.05 V(vs NHE), in excellent agreement with the previous literature value of 1.34 V.

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“…Temperature dependence of phosphorescence decay is accompanied by a pressure dependence [124]. 3 dσ*pσ lifetimes of Rh(TMB) and Ir(pz)(CO)(cod) increase with increasing pressure, with activation volumes of +4.6 and +2.8 cm 3 mol -1 in MeCN.…”

Section: Dσ*pσ Lifetimes and Intersystem Crossingmentioning

confidence: 99%

“…3 dσ*pσ lifetimes of Rh(TMB) and Ir(pz)(CO)(cod) increase with increasing pressure, with activation volumes of +4.6 and +2.8 cm 3 mol -1 in MeCN. These increases were interpreted [124] as evidence for a strong-coupling [120] decay mechanism whereby the excited molecules undergo expansive distortion to achieve a crossing point with the groundstate potential energy surface. On the other hand, very weak pressure dependence and small negative volumes of activation were determined [124] in MeCN for Pt(pop) (-0.2 cm 3 mol -1 ) and…”

Section: Dσ*pσ Lifetimes and Intersystem Crossingmentioning

confidence: 99%

Electronic structures and photophysics of d8-d8 complexes

Gray

Záliš

Vlček

2017

Coordination Chemistry Reviews

108

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Harry B. Gray), zalis@jh-inst.cas.cz (Stanislav Záliš), a.vlcek@qmul.ac.uk (Antonín Vlček) Dedicated to Barry Lever, consummate scholar and treasured friend, in recognition of his deep and lasting contributions to coordination chemistry. Abstract Research on d 8 -d 8 complexes is being actively pursued, owing, in part, to newly developed timeresolved optical, IR, and X-ray methods that directly interrogate bonding changes upon excitation. Our review covers work on the ground-and electronic excited states, as well as the oxidized and reduced forms, of these complexes. Recent experimental and theoretical results add a new chapter to the rich history of d 8 -d 8 spectroscopic and chemical behavior.2 4.2. 3 dσ*pσ decay mechanism ……………………………………………………………………………………….. 4.3. Singlet and triplet excited-state properties and reactivity ………………………………………… 4.4. Excited-state spectroscopy ………………………………………………………………………………………. 4.5. Vibrational coherence ……………………………………………………………………………………………… 4.6. Relaxation of higher excited states …………………………………………………………………………… 4.7. Metal-metal to ligand charge transfer and ligand-centered excited states ………………. 5. Conclusions …………………………………………………………………………………………………………………………….. Acknowledgments ……………………………………………………………………………………………………………………… Appendix: computational details ………………………………………………………………………………………………… References ………………………………………………………………………………………………………………………………….

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Pressure effects on the photophysical properties of the platinum(II) dimer Pt2(POP)44- (POP = .mu.-.eta.2-H2P2O52-) and related d8-d8 dinuclear complexes in solution

Cited by 21 publications

References 0 publications

Salt and Specific Cation Effects in the Quenching of Triplet State Tetrakis(μ-pyrophosphite-P,P‘)diplatinate(II) by Acidopentacyanocobaltate(III) Anions

Salt and Specific Cation Effects in the Quenching of Triplet State Tetrakis(μ-pyrophosphite-P,P‘)diplatinate(II) by Acidopentacyanocobaltate(III) Anions

Quenching of Triplet State Tetrakis(μ-pyrophosphito-PP‘)diplatinate(II) by Nickel(II) Macrocyclic and Tris-diimine Complexes

Electronic structures and photophysics of d8-d8 complexes

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