Homoleptic Tris-Diphosphine Re(I) and Re(II) Complexes and Re(II) Photophysics and Photochemistry

Adams, Jeramie J.; Arulsamy, Navamoney; Sullivan, B. Patrick; Roddick, Dean M.; Neuberger, A.; Schmehl, Russell H.

doi:10.1021/acs.inorgchem.5b01395

Cited by 22 publications

(24 citation statements)

References 82 publications

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“…A recent example of this phenomenon can be found in the study of the photochemical properties of [(P-P) 3 Re] 1+/2+ pairs by Roddick, Schmehl, and coworkers. 58 The physical origin of this elongation has been the subject of great interest, given that oxidation of the metal might be expected to generate a stronger Lewis acid with a more strongly s-bound ligand Lewis Further exacerbating this discomfort, the linear [ML 2 ] 0/+ redox pairs reported here exhibited all the same structural changes outlined above, yet the orbital depopulated on oxidation has been demonstrated computationally and experimentally to be mostly non-bonding. Consequently, there cannot be a net depopulation of an M/L p-backbonding orbital, although decreased backbonding might be expected as the energy difference between the metal orbitals and s* increases (vide supra).…”

Section: General Consideration Of M-p Bond Elongation Upon Oxidationmentioning

confidence: 73%

Cationic Two-Coordinate Complexes of Pd(I) and Pt(I) Have Longer Metal-Ligand Bonds Than Their Neutral Counterparts

MacInnis

DeMott

Zolnhofer

et al. 2016

Chem

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Ozerov and colleagues describe the synthesis and characterization of linear, twocoordinate, cationic phosphine complexes of monovalent Pd and Pt. Comparison of the structures of these complexes to the neutral, zero-valent analogs revealed significant elongation of the M-P bond upon oxidation. Computational studies offer an explanation for the observed phenomenon, showing that molecularorbital-based arguments alone cannot provide a satisfactory rationalization. HIGHLIGHTS Two-coordinate, cationic complexes of monovalent Pd and Pt are synthesized The monovalent cations possess longer, stronger M-L bonds than their zero-valent analogs Theoretical consideration of electrostatic and Pauli effects offers an explanation MacInnis et al., Chem 1, 902-920 December 8, 2016 ª 2016 Elsevier Inc. http://dx.SUMMARY One-electron oxidation of known ( t Bu 3 P) 2 M (1, M = Pd; 2, M = Pt) with [Ph 3 C] [HCB 11 Cl 11 ] leads to two-coordinate, monovalent cations of the formula [( t Bu 3 P) 2 M][HCB 11 Cl 11 ] (3, M = Pd; 4, M = Pt), which also possess linear geometry but with elongated M-P bonds. Spectroscopic and computational studies consistently show that the unpaired electron of the d 9 configuration of 3 and 4 belongs to largely non-bonding orbitals: the s/d z2 hybrid for Pd and the degenerate d x2-y2 /d xy pair for Pt. We show that molecular-orbital-based arguments alone are incapable of predicting or rationalizing the observed M-P bond lengthening on oxidation; correct prediction and rationalization are achieved only by inclusion of electrostatic and Pauli effects. This emphasizes the dangers of interpreting any perturbative changes in bond metrics solely on the basis of energies and occupancies of molecular orbitals; the inclusion of electrostatic and Pauli components is essential to providing a more complete picture. 7 8 9 10 Scheme 1. Synthesis and Reactivity of Pd(I) and Pt(I) Complexes

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Section: General Consideration Of M-p Bond Elongation Upon Oxidationmentioning

confidence: 73%

Cationic Two-Coordinate Complexes of Pd(I) and Pt(I) Have Longer Metal-Ligand Bonds Than Their Neutral Counterparts

MacInnis

DeMott

Zolnhofer

et al. 2016

Chem

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“…This highlights the significant excited state oxidation and reduction potential of complex 29 [54,109]. In particular, this includes a very strong photo-oxidizing capacity for the 2 LMCT state that emerges as a common feature, together with a few earlier known photoredox-active Tc(II) and Re(II) complexes [110][111][112].…”

Section: Photocatalysismentioning

confidence: 83%

“…Catalysts 2020, 10, x FOR PEER REVIEW 24 of 32 for the 2 LMCT state that emerges as a common feature, together with a few earlier known photoredox-active Tc(II) and Re(II) complexes [110][111][112]. A generalized kinetics schematic for bimolecular photoredox-quenching involving an Fe(III) light-harvesting complex and an electron donor as quencher (Q) is shown in Figure 16.…”

Section: Photocatalysismentioning

confidence: 97%

“…Finally, the new and largely unexplored photochemical properties of the Fe(III)NHC complexes provide an interesting area for fundamental studies of photocatalytic reaction mechanisms featuring the unconventional 2 LMCT excited state. Given the promising excited state properties of this type of low-spin LMCT photochemically active complexes, combined with overall scarcity of other examples of such photoredox-processes in general (mainly limited to a few examples involving rare Tc(II) and Re(II) complexes [110,111,114]), this provides an important area for further investigations that has the potential to be of broader interest beyond the Fe(III)NHC complexes.…”

Section: Photocatalysismentioning

confidence: 99%

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Photophysics and Photochemistry of Iron Carbene Complexes for Solar Energy Conversion and Photocatalysis

et al. 2020

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Earth-abundant first row transition metal complexes are important for the development of large-scale photocatalytic and solar energy conversion applications. Coordination compounds based on iron are especially interesting, as iron is the most common transition metal element in the Earth’s crust. Unfortunately, iron-polypyridyl and related traditional iron-based complexes generally suffer from poor excited state properties, including short excited-state lifetimes, that make them unsuitable for most light-driven applications. Iron carbene complexes have emerged in the last decade as a new class of coordination compounds with significantly improved photophysical and photochemical properties, that make them attractive candidates for a range of light-driven applications. Specific aspects of the photophysics and photochemistry of these iron carbenes discussed here include long-lived excited state lifetimes of charge transfer excited states, capabilities to act as photosensitizers in solar energy conversion applications like dye-sensitized solar cells, as well as recent demonstrations of promising progress towards driving photoredox and photocatalytic processes. Complementary advances towards photofunctional systems with both Fe(II) complexes featuring metal-to-ligand charge transfer excited states, and Fe(III) complexes displaying ligand-to-metal charge transfer excited states are discussed. Finally, we outline emerging opportunities to utilize the improved photochemical properties of iron carbenes and related complexes for photovoltaic, photoelectrochemical and photocatalytic applications.

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“…We selected the known ferrocenium salt [Fc]Cl 24 and commercial [Fc]PF 6 and [Fc]BF 4 to investigate the influence of the counterion on the decomposition rate. We generated the complex [Fc]CSA [CSA = camphor-10-sulfonate ()] in solution, which has also been included in this study.…”

Section: Scheme 1 Propargylic Substitution Reactionmentioning

confidence: 99%

Ferrocenium Ions as Catalysts: Decomposition Studies and Counteranion Influence on Catalytic Activity

Jurkowski¹,

Bauer²

2020

Synthesis

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Catalyst decomposition has a negative effect on catalytic activity, and knowledge of decomposition pathways can assist with catalyst development. Ferrocenium cations have been employed as catalysts in a number of organic transformations, and we investigated the stability of a number of ferrocenium salts in solution. The observed rate decomposition constants for [Fc]Cl, [Fc]PF6, [Fc]BF4, [Fc]CSA [Fc = ferrocenium, CSA = camphor-10-sulfonate (β)], [AcFc]SbF6, (AcFc = acetylated ferrocene), and [FcB(OH)2]SbF6 [FcB(OH)2 = ferrocenylboronic acid] were determined in CH2Cl2 solution by time-resolved UV-vis spectroscopy. The rate decomposition constants depended on the nature of the counterion, with [Fc]Cl being the most stable complex in solution. The decomposition rate constants dropped by roughly an order of magnitude in most cases when the experiments were performed in nitrogenated solvent, demonstrating that the decomposition is mainly an oxidative process. The cosolvent HFIP (1,1,1,3,3,3-hexafluoropropan-2-ol) slowed the decomposition of the ferrocenium cations as well. Many catalytic or stoichiometric reactions of ferrocenium cations are performed with alcohols; we determined that hexan-1-ol is decomposed over the course of 16 hours, but not oxidized in the presence of a ferrocenium cation. Finally, the different ferrocenium cations were employed in a test reaction to determine catalytic activity. The nucleophilic substitution of hydroxyl groups in a tertiary propargylic alcohol by an alcohol is catalyzed by all complexes, and, again, a counterion dependency of the catalytic activity was observed. Also, HFIP increases the catalytic activity of the ferrocenium cations. The research has importance in the development of ferrocenium-based catalyst systems, because changes in the counterion as well as the architecture of the ferrocenium cation have an influence on stability and catalytic activity.

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Homoleptic Tris-Diphosphine Re(I) and Re(II) Complexes and Re(II) Photophysics and Photochemistry

Cited by 22 publications

References 82 publications

Cationic Two-Coordinate Complexes of Pd(I) and Pt(I) Have Longer Metal-Ligand Bonds Than Their Neutral Counterparts

Cationic Two-Coordinate Complexes of Pd(I) and Pt(I) Have Longer Metal-Ligand Bonds Than Their Neutral Counterparts

Photophysics and Photochemistry of Iron Carbene Complexes for Solar Energy Conversion and Photocatalysis

Ferrocenium Ions as Catalysts: Decomposition Studies and Counteranion Influence on Catalytic Activity

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