+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Vibronic coupling in dicyano-complex-bridged mixed-valence complexes. Relaxation of vibronic constraints in systems with degenerate bridging-ligand and electron-transfer excited states

Vibronic coupling in dicyano-complex-bridged mixed-valence complexes. Relaxation of vibronic constraints in systems with degenerate bridging-ligand and electron-transfer excited states

Inorganic Chemistry 39(3): 437-446

Intense near-infrared (NIR) absorption bands have been found in mixed-valence Ru(NH3)5(2+,3+) complexes bridged by trans-Ru(py)4(CN)2 and cis-Os(bpy)2(CN)2, epsilonmax approximately 1.5 x 10(3) cm(-1) and deltav1/2 approximately 5 x 10(3) cm(-1) for bands at 1,000 and 1,300 nm, respectively. The NIR transitions implicate substantial comproportionation constants (64 and 175, respectively) characteristic of moderately strong electronic coupling in the mixed-valence complexes. This stands in contrast to the weakly forbidden electronic coupling of Ru(NH3)5(2+,3+) couples bridged by M(MCL)(CN)2+ complexes (MCL = a tetraazamacrocyclic ligand) (Macatangay; et al. J. Phys. Chem. 1998, 102, 7537). A straightforward perturbation theory argument is used to account for this contrasting behavior. The electronic coupling between a cyanide-bridged, donor-acceptor pair, D-(CN-)-A, alters the properties of the bridging ligand. Such systems are described by a "vibronic" model in which the electronic matrix element, HDA, is a function of the nuclear coordinates, QN, of the bridging ligand: HDA = HDA degrees + bQN. Electronic coupling in the dicyano-complex-bridged, D-[(NC)M(CN)]-A, systems is treated as the consequence of the perturbational mixing of the "local", D(NC)M and M(CN)A, vibronic interactions. If M is an electron-transfer acceptor, then the nuclear coordinates are assumed to be configured so that bQN is larger for D(NC)M but very small (bQN approximately 0) for M(CN)A. When the vertical energies of the corresponding charge-transfer transitions, EDM and EDA, differ significantly, a perturbation theory treatment results in HDA = HDAHAM/Eave independent of M and consistent with the earlier report. When EDM approximately equals EDA, configurational mixing of the excited states leads to HDA proportional to HDM, consistent with the relatively intense intervalence bands reported in this paper. Some implications of the model are discussed.

Please choose payment method:

(PDF emailed within 1 workday: $29.90)

Accession: 047932752

Download citation: RISBibTeXText

PMID: 11229560

Related references

Vibronic Participation of the Bridging Ligand in Electron Transfer and Delocalization: New Application of a Three-State Model in Pyrazine-Bridged Mixed-Valence Complexes of Trinuclear Ruthenium Clusters. Journal of Physical Chemistry A 107(44): 9301-9311, 2003

Excited-state electronic coupling and photoinduced multiple electron transfer in two related ligand-bridged hexanuclear mixed-valence compounds. Inorganic Chemistry 41(17): 4389-4395, 2002

Charge-transfer transitions in triarylamine mixed-valence systems: A joint density functional theory and vibronic coupling study. Journal of the American Chemical Society 124(35): 10519-10530, September 4, 2002

Chemistry of Vibronic Coupling. 3. How One Might Maximize Off-Diagonal Dynamic Vibronic Coupling Constants for Intervalence Charge-Transfer (Ivct) States in an Aba System (A, B = Alkali Metal, H, Halogen)?. The Journal of Physical Chemistry A 104(43): 9740-9749, 2000

Vibronic coupling in cyclopentadienyl radical: a method for calculation of vibronic coupling constant and vibronic coupling density analysis. Journal of Chemical Physics 124(2): 024314, 2006

Vibronic couplings and coherent electron transfer in bridged systems. Physical Chemistry Chemical Physics 17(46): 30937-30945, 2016

Dependence of Vibronic Coupling on Molecular Geometry and Environment: Bridging Hydrogen Atom Transfer and Electron-Proton Transfer. Journal of the American Chemical Society 137(42): 13545-13555, 2016

Excited-State Distortions and Electron Delocalization in Mixed-Valence Dimers: Vibronic Analysis of the Near-IR Absorption and Resonance Raman Profiles of [Fe(2)(OH)(3)(tmtacn)(2)](2+). Inorganic Chemistry 35(15): 4323-4335, 1996

Interstate vibronic coupling constants between electronic excited states for complex molecules. Journal of Chemical Physics 148(12): 124119, 2018

Vibronic coupling in benzene cation and anion: vibronic coupling and frontier electron density in Jahn-Teller molecules. Journal of Chemical Physics 124(15): 154303, 2006

Double exchange and vibronic coupling in mixed valence systems: Origin of the broken-symmetry ground state of (Fe-3S-4)-0 cores in proteins and models. Journal of the American Chemical Society 115(12): 5155-5168, 1993

Double-exchange and vibronic coupling in mixed-valence systems Electronic structure of -3+ clusters in high-potential iron protein and related models. Journal of the American Chemical Society 116(12): 5362-5372, 1994

Localization-Delocalization in Bridged Mixed-Valence Metal Clusters: Vibronic PKS Model Revisited. Journal of Physical Chemistry. a 119(38): 9844-9856, 2015

Coriolis coupling in degenerate vibronic states of spherical top molecules. Molecular Physics 22(6): 1035-1040, 1971

Vibronic interactions and possible electron pairing in the photoinduced excited electronic States in molecular systems: a theoretical study. Journal of Physical Chemistry. a 109(21): 4804-4815, 2006