Charge-Transfer Transitions CT

When both electron donor (D) and acceptor (A) groups are attached to a TT-electron system it is not possible to consider the transition in terms of the excitation of one electron since it is a composite of several different one-electron excitation types. An example of a molecule which has electronic transitions of this type is Michler s ketone  

Porter has termed these transitions charge-transfer excitations (CT). Possible one-electron contributions to the excitation of a molecule represented as DRA (D, donor R, chromophore A, acceptor) are 

Where the -I- — terms refer to I a type excitations and the to a tt w type transition. These absorptions occur at longer wavelengths than the related model compounds (benzene and dimethylamine for Michler s ketone), have a high intensity, 10 liter/mole-cm, a small singlet-triplet splitting, and undergo a red shift of the absorption on going to a more polar solvent. 

Calculate the energy (kcal/mole) corresponding to light of wavelength (a) 365 nm (b) 313 nm (c) 254 nm. 

Given the data for a unimolecular photochemical reaction, A , = 5 x 10 mole/sec, 4 p = 0.75, and 7o = 3 x 10 quanta/sec, calculate the time required for the reaction to produce 1 mole of product. 

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Energies of the ligand-to-metal charge-transfer transitions CT (from reflectance spectra) for various 1 1 complexes between coronands or cryptands and lanthanide perchlorates, and optical electronegativities Xapt the ligands. 

Optical charge transfer (CT) is commonly observed in un-symmetrical molecules or molecular complexes in which there are sites of distinctly different ionization energies and electron affinities. The origin and properties of optical charge transfer transitions provide the basis for this account. A convenient place to begin chemically is with mixed-valence compounds and two examples are shown below (1-3). In the first (eq 1), the sites of different oxidation states are held in close... 

Figure 4.75 Schematic representation of the charge transfer in various excited states of a metal complex. M is the metal centre and L stands for a ligand. LF is a ligand field transition, CTs are the charge transfer transitions, LL is an intraligand transition, and CTTS is a charge transfer to solvent...

Crystallization, experimental methods overview, 1, 207 Crystal mounting, experimental methods overview, 1, 209 Crystal selection, experimental methods overview, 1, 209 CSA, and apparent dynamic NMR, 1, 423 CSD, see Cambridge Structural Database C2-symmetric metallocenes, for polypropylene polymerization, 4, 1058 CT transitions, see Charge-transfer transitions Cubanes... 

Charge transfer salt (CTS) (TMTTF)2SbFg has been studied by Yu et al.120 using 13C NMR spectroscopy. It is known that at ambient pressure, a transition to a... 

CT Charge-transfer transition, excitation or excited state. Detailed character (herein MLCT, XLCT, or LLCT) not specified DFT Density functional theory... 

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