Experimental probes of the electronic matrix element contributions to bimolecular reactions: metal-to-ligand charge-transfer perturbations of electronic transfer rates

The nonequilibrium Fermi’s golden rule (NE-FGR) describes the time-dependent rate coefficient for electronic transitions, when the nuclear degrees of freedom start out in a nonequilibrium state. In this letter, the linearized semiclassical (LSC) approximation of the NE-FGR is used to calculate the photoinduced charge transfer rates in the carotenoid-porphyrin-C60 molecular triad dissolved in explicit tetrahydrofuran. The initial nonequilibrium state corresponds to impulsive photoexcitation from the equilibrated ground-state to the ππ* state, and the porphyrin-to-C60 and the carotenoid-to-C60 charge transfer rates are calculated. Our results show that accounting for the nonequilibrium nature of the initial state significantly enhances the transition rate of the porphyrin-to-C60 CT process. We also derive the instantaneous Marcus theory (IMT) from LSC NE-FGR, which casts the CT rate coefficients in terms of a Marcus-like expression, with explicitly time-dependent reorganization energy and reaction free energy. IMT is found to reproduce the CT rates in the system under consideration remarkably well.

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Synthesis and Photochemical Properties of Re(I) Tricarbonyl Complexes Bound to Thione and Thiazole-2-ylidene Ligands

10.26434/chemrxiv.12324875 ◽

2020 ◽

Author(s):

Matthew Stout ◽

Brian Skelton ◽

Alexandre N. Sobolev ◽

Paolo Raiteri ◽

Massimiliano Massi ◽

...

Keyword(s):

Charge Transfer ◽

Excited States ◽

Ligand Exchange ◽

Ligand Substitution ◽

Bidentate Ligand ◽

The Other ◽

Ligand Exchange Reaction ◽

Multiple Products ◽

Ligand Charge Transfer ◽

Photochemical Properties

Three Re(I) tricarbonyl complexes, with general formulation Re(N^L)(CO)3X (where N^L is a bidentate ligand containing a pyridine functionalized in the position 2 with a thione or a thiazol-2-ylidene group and X is either chloro or bromo) were synthesized and their reactivity explored in terms of solvent-dependent ligand substitution, both in the ground and excited states. When dissolved in acetonitrile, the complexes bound to the thione ligand underwent ligand exchange with the solvent resulting in the formation of Re(NCMe)2(CO)3X. The exchange was found to be reversible, and the starting complex was reformed upon removal of the solvent. On the other hand, the complexes appeared inert in dichloromethane or acetone. Conversely, the complex bound to the thiazole-2-ylidene ligand did not display any ligand exchange reaction in the dark, but underwent photoactivated ligand substitution when excited to its lowest metal-to-ligand charge transfer manifold. Photolysis of this complex in acetonitrile generated multiple products, including Re(I) tricarbonyl and dicarbonyl solvato-complexes as well as free thiazole-2-ylidene ligand.

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Density Functional Study of Metal-to-Ligand Charge Transfer and Hole-Hopping in Ruthenium(II) Complexes with Alkyl-Substituted Bipyridine Ligands

ACS Omega ◽

10.1021/acsomega.0c01199 ◽

2020 ◽

Author(s):

Salmahaminati ◽

Minori Abe ◽

Indra Purnama ◽

Jacob Yan Mulyana ◽

Masahiko Hada

Keyword(s):

Charge Transfer ◽

Density Functional ◽

Functional Study ◽

Density Functional Study ◽

Ligand Charge Transfer

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Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered

Molecules ◽

10.3390/molecules26040981 ◽

2021 ◽

Vol 26 (4) ◽

pp. 981

Author(s):

Mason D. Hart ◽

John J. Meyers ◽

Zachary A. Wood ◽

Toshinori Nakakita ◽

Jason C. Applegate ◽

...

Keyword(s):

Charge Transfer ◽

Coordination Chemistry ◽

Single Crystal ◽

13C Nmr ◽

Quantitative Assessment ◽

X Ray ◽

New Class ◽

Linear Relationships ◽

Ligand Charge Transfer ◽

Donor Characteristics

Isocyanoazulenes (CNAz) constitute a relatively new class of isocyanoarenes that offers rich structural and electronic diversification of the organic isocyanide ligand platform. This article considers a series of 2-isocyano-1,3-X2-azulene ligands (X = H, Me, CO2Et, Br, and CN) and the corresponding zero-valent complexes thereof, [(OC)5Cr(2-isocyano-1,3-X2-azulene)]. Air- and thermally stable, X-ray structurally characterized 2-isocyano-1,3-dimethylazulene may be viewed as a non-benzenoid aromatic congener of 2,6-dimethyphenyl isocyanide (2,6-xylyl isocyanide), a longtime “workhorse” aryl isocyanide ligand in coordination chemistry. Single crystal X-ray crystallographic {Cr–CNAz bond distances}, cyclic voltametric {E1/2(Cr0/1+)}, 13C NMR {δ(13CN), δ(13CO)}, UV-vis {dπ(Cr) → pπ*(CNAz) Metal-to-Ligand Charge Transfer}, and FTIR {νN≡C, νC≡O, kC≡O} analyses of the [(OC)5Cr(2-isocyano-1,3-X2-azulene)] complexes provided a multifaceted, quantitative assessment of the π-acceptor/σ-donor characteristics of the above five 2-isocyanoazulenes. In particular, the following inverse linear relationships were documented: δ(13COtrans) vs. δ(13CN), δ(13COcis) vs. δ(13CN), and δ(13COtrans) vs. kC≡O,trans force constant. Remarkably, the net electron withdrawing capability of the 2-isocyano-1,3-dicyanoazulene ligand rivals those of perfluorinated isocyanides CNC6F5 and CNC2F3.

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