Triplet excited-state chemistry of diplatinum(II) complexes: comparative spectroscopy and quenching rate constants between the tetrakis(.mu.-pyrophosphito)diplatinate(II) and the tetrakis[.mu.-methylenebis(phosphonito)]diplatinate(II) tetraanions

Roundhill, D. Max; Shen, Z.-P.; King, Christopher L.; Atherton, Stephen J.

doi:10.1021/j100325a021

Cited by 20 publications

(24 citation statements)

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“…It is important to study the factors affecting the photophysical and photochemical properties of luminescent gold(I) complexes, which have been receiving growing interest over the past several years. − , The open coordination framework of two-coordinate gold(I) is important for it to be able to undergo substrate-binding reactions in the ground and excited states. − The studies 32 on the association constants of [Au 2 (dcpm) 2 ] 2+ and halide ions indicated that the high affinity of two-coordinate gold(I) to undergo substrate-binding reactions is in contrast to the square-planar d 8 platinum(II) system, which remains four-coordinate in most instances. , It is of interest to compare the binuclear Au(I) phosphine with the classic binuclear platinum(II) photocatalyst [Pt 2 (P 2 O 5 H 2 ) 4 ] 4- in both experiment and theory. − …”

Section: Resultsmentioning

confidence: 99%

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Ab Initio Studies on Metal−Metal Interaction and ³[σ*(d)σ(s)] Excited State of the Binuclear Au(I) Complexes Formed by Phosphine and/or Thioether Ligands

Pan

Zhang

2004

J. Phys. Chem. A

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The structures of ground state and lowest energy triplet excited state for [Au 2 (PH 2 2+ (3) as well as their solvated 1-3‚(MeCN) 2 species are fully optimized by the MP2 and CIS methods, respectively. The 3 [σ*(d)σ(s)] excited states give the 300-390 emissions in the gas phase, red shifting to 500-730 nm in acetonitrile. The coordination of solvent molecule to the gold atom in the excited states is responsible for such a red shift. For 2, all the possible geometries, the substituent effect of methyl groups on P and/or S atoms and the comparison with thiolate complex [Au 2 (PH 2 -CH 2 PH 2 )(SCH 2 S)] ( 6) are discussed. The unrestricted MP2 calculations on 1-3, head-to-tail [Au 2 (PH 2 CH 2 -SH) 2 ] 2+ (7) and head-to-head [Au 2 (PH 2 CH 2 SH) 2 ] 2+ (8) confirm the CIS results in both optimized geometry and emissive energy related to the 3 [σ*(d)σ(s)] state. The frequency calculations at the MP2 level indicate that the Au(I)-Au(I) interaction is weak in the ground state (ν(Au 2 ) ) 89-101 cm -1 ) but is strongly strengthened in the excited state (ν(Au 2 ) ) 144-189 cm -1 ).

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Section: Resultsmentioning

confidence: 99%

“…88,89 It is of interest to compare the binuclear Au(I) phosphine with the classic binuclear platinum(II) photocatalyst [Pt 2 (P 2 O 5 H 2 ) 4 ] 4in both experiment and theory. [90][91][92][93][94][95][96][97][98] 3.1. Ground-and Excited-State Structures of 1-3 and Their Solvated Species.…”

Section: Resultsmentioning

confidence: 99%

Ab Initio Studies on Metal−Metal Interaction and ³[σ*(d)σ(s)] Excited State of the Binuclear Au(I) Complexes Formed by Phosphine and/or Thioether Ligands

Pan

Zhang

2004

J. Phys. Chem. A

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“…Unfortunately, experiments cannot be carried out in bulk KI as I - quenches 3 Pt 2 (pop) 4 4- reductively in aqueous solution with a quenching rate constant log k q = 5.7.…”

Section: Resultsmentioning

confidence: 99%

Atom Transfer Processes in Oxidative Quenching of Triplet State Tetrakis(μ-pyrophosphite-P,P‘)diplatinate(II) by Acidopentacyanocobaltate(III) Anions

Kirk

Cai

1998

Inorg. Chem.

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In the presence of high electrolyte concentration to screen the Coulomb repulsion, the emission of 3Pt2(pop)4 4- (where pop = μ-pyrophosphite-P,P‘) can be quenched by the complexes Co(CN)5X3- (where X = I, Br, Cl, N3). In acidic aqueous solutions the quenching involves the eventual reduction of the cobalt complexes to Co2+ aq and gives the oxidative quenching products Pt2 III(pop)4X2 4- (X = I, Br, Cl). For the reaction of 3Pt2(pop)4 4- with Co(CN)5I3- and Co(CN)5Br3- in 0.5 M KCl/pH 2 solution, the product yields per quenching event are 0.34 and 0.21, respectively. Steady-state photolysis using the Co(CN)5I3- quencher in 0.5 M KCl medium gave predominantly Pt2(pop)4I2 4- as product with only small amounts of Pt2(pop)4ICl4-, pointing to a direct iodine atom-transfer process. In contrast, Co(CN)5Br3- quencher gave Pt2(pop)4Cl2 4- under the same conditions, possibly indicative of electron transfer. However, study of the mixed-valence platinum dimer intermediates formed by laser flash transient spectroscopy provides conclusive evidence for atom transfer as the dominant primary reactive quenching step for all three halopentacyanocobaltates. The steady-state results for Co(CN)5Br3- quencher arose via the interconversion of the monobromo mixed-valence platinum dimer intermediate to its chloro analogue in chloride solutions. Co(CN)5N3 3- gave a mixture of oxidation products and no intermediate corresponding to electron transfer, indicating a complex interaction with 3Pt2(pop)4 4-.

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“…The well-known diplatinum(II) complex K 4 Pt 2 (µ-P 2 O 5 H 2 ) 4 , more commonly referred to as "platinum pop" or Pt 2 (pop) 4 4-, has become an important tool used by the inorganic photochemist. Since its discovery, 1 the unique photochemical and photophysical properties of this complex have made it very useful in the study of both oxidative 2 and reductive 3,4 photoinduced electron-transfer reactions as well as in the study 5 of excited-state atom transfer processes. Recent studies 6 have looked at the salt effects and specific cation effects in the quenching of 3 Pt 2 (pop) 4 4by a series of acidopentacyanocobalt-(III) complexes and found evidence for both oxidative electron transfer and atom transfer mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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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Triplet excited-state chemistry of diplatinum(II) complexes: comparative spectroscopy and quenching rate constants between the tetrakis(.mu.-pyrophosphito)diplatinate(II) and the tetrakis[.mu.-methylenebis(phosphonito)]diplatinate(II) tetraanions

Abstract: Triplet Excited-State Chemistry of Diplatinum(II) Complexes. Comparative Spectroscopy and Quenching Rate Constants between the Tetrakls(/¿-pyrophosphlto)diplat¡nate(II) and the Tetrakls[)U-methylenebis(phosphonlto)]dlplatlnate(II) Tetraanions

Cited by 20 publications

References 12 publications

Ab Initio Studies on Metal−Metal Interaction and ³[σ*(d)σ(s)] Excited State of the Binuclear Au(I) Complexes Formed by Phosphine and/or Thioether Ligands

Ab Initio Studies on Metal−Metal Interaction and ³[σ*(d)σ(s)] Excited State of the Binuclear Au(I) Complexes Formed by Phosphine and/or Thioether Ligands

Atom Transfer Processes in Oxidative 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

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Triplet excited-state chemistry of diplatinum(II) complexes: comparative spectroscopy and quenching rate constants between the tetrakis(.mu.-pyrophosphito)diplatinate(II) and the tetrakis[.mu.-methylenebis(phosphonito)]diplatinate(II) tetraanions

Abstract: Triplet Excited-State Chemistry of Diplatinum(II) Complexes. Comparative Spectroscopy and Quenching Rate Constants between the Tetrakls(/¿-pyrophosphlto)diplat¡nate(II) and the Tetrakls[)U-methylenebis(phosphonlto)]dlplatlnate(II) Tetraanions

Cited by 20 publications

References 12 publications

Ab Initio Studies on Metal−Metal Interaction and 3[σ*(d)σ(s)] Excited State of the Binuclear Au(I) Complexes Formed by Phosphine and/or Thioether Ligands

Ab Initio Studies on Metal−Metal Interaction and 3[σ*(d)σ(s)] Excited State of the Binuclear Au(I) Complexes Formed by Phosphine and/or Thioether Ligands

Atom Transfer Processes in Oxidative 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

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Ab Initio Studies on Metal−Metal Interaction and ³[σ*(d)σ(s)] Excited State of the Binuclear Au(I) Complexes Formed by Phosphine and/or Thioether Ligands

Ab Initio Studies on Metal−Metal Interaction and ³[σ*(d)σ(s)] Excited State of the Binuclear Au(I) Complexes Formed by Phosphine and/or Thioether Ligands