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A semiclassical model is proposed for interfacial charge-transfer absorption (IFCTA) to metals and semiconductors that consider the fact that, unlike molecules, both semiconductors and metals possess closely spaced occupied electronic levels and closely spaced unoccupied levels so that a common framework is appropriate for describing their interfacial charge-transfer processes. It is concluded that the photoinduced charge-transfer processes involve a small number of atoms per acceptor site on the surface of the nanoparticle.

The development of an electron-hopping model for charge transport through donor-bridge-acceptor assemblies is presented. A detailed electrostatic analysis of the assembly is made for this purpose.

The structures of the pentaammineruthenium pyridine and benzonitrile complexes as well as its role as a function of oxidation state were investigated through x-ray crystallography. It was indicated that the inner-shell barriers for pyrazine and N-methylpyrazinium pairs were significant. These inner-shell barriers determine the order of magnitude in the self-exchange rates.

(NH3)5Ru(III) and (NH3)5Ru(II) exhibited low affinity for the protonated amide ligands, which stabilized the III oxidation state. A bonding-to-antibody character was observed in the amido Ru(III) complexes due to the strong pi p-pi d interactions between the partially-vacant Ru(III) orbital and the amido lone pair. Ru(II) complexes revealed MLCT transitions that occurred at the charge-transfer limit.

Aqueous media reveal the presence of an *OsVIO2(tmc)2+/OsVO2(tmc)+ pair, whose properties are determined. The aqua-ion quenchers reveal a steady behavior and a self-exchange rate. Small anions participate in the self-exchange rates of numerous pairs, and their properties are determined by employing a highly oxidizing excited state. The quenching data and the halogen pairs reveal different self-exchange rates. A powerful electronic reaction is assumed to participate in the interaction between the halides and the outer-sphere pairs.

The equilibrium between five-coordinate CoL(CO2)+ and six-coordinate CoL(CO2)(CD3CN)+ cobalt macrocycles was examined by both nuclear magnetic resonance and infrared spectroscopy as a function of temperature. It was shown that the binding of CO2 via both its electrophilic center (carbon atom) and its nucleophilic center (oxygen atom) is involved in the stabilization of the CO2 complex at low temperature.

Two assymetric species mixed-valence species, the first bridged by an isonicotinato and the second by an isonicotinamido were synthesized and characterized. The hydrolysis of the diruthenium(III) mu-4-cyanopyridine complex was used to yield the mu-amido complexes. It was found that the differential stabilization of Ru(III) over Ru(II) was greater for the amido than for the carboxylato ligand. The positions of the Ru(II)-pyridine MLCT band energies revealed that pentaammineruthenium(III) was an electron-withdrawing group.

Thermodynamic and kinetic parameters for the oxidative addition of H2 to [Rh(super I)(bpy)2](super +) to form [Rh(super III(H)2(bpy)2](super +) are determined from either the UV-vis spectrum of equilibrium mixtures of [Rh(super 1)(bpy)2](super +) and [Rh(super III(H)2(bpy)2](super +) or form the observed rates of dihydride formation. This is followed by visible-light irradiation of solutions containing [Rh(super III)(H)2(bpy)2](super +) as a function of H2 concentration, temperature and pressure in acetone and methanol.

Interfacial charge-transfer absorption (IFCTA) provides information concerning the barriers to charge transfer between molecules and the metal/semiconductor and the magnitude of the electronic coupling and could provide a powerful tool for understanding interfacial charge-transfer kinetics. It is concluded that the electronic coupling between molecular adsorbates and the metal levels is so small that the adsorption is not detectable, whereas for semiconductors there may be intense features involving coupling to surface states.

A donor-bridge-acceptor (D-B-A) system inserted between two metal electrodes exhibit Ohmic behavior and positive differential conductances at small applied voltages and a symmetrical D-B-A systems shows negative differential conductances of being in the inverted region at greater driving force. By utilizing D/A couples with small lambda values, switching can be achieved at modest applied potentials.

An examination is done of the transient photocurrent experiments, which are used to calculate the free radical ion quantum yield of a number of alkylbenzene electron donors with the electron acceptor tetracyanoethylene (TCNE). In conclusion, free ion yields calculated using Onsager theory and a simple excitation function for the random pairs fit the experimental results quite well and supports the model.

The step of oxidative addition of H(sub2) to a transition metal complex is important in certain catalytic hydrogenation and hydroformylation reactions. H(sub2) may operated as a two-electron sigma-bonding ligand and such compounds may act as intermediates in H(sub2) oxidative addition reactions. The oxidative addition of H(sub2) to bis(2,2'-bipyridine)rhodium(I), forming the corresponding RHIII cis-dihydride, has been investigated. Evidence of the net transfer of H(sub2) in the bimolecular self-exchange reaction is presented.

The change observed in ligand polarization which reduces the expected dipole-moment change is due to the change in the charge of the metal center produced by charge-transfer excitation. The effect indicates good agreement with a two-state model for MLCT and LMCT transitions. The effects of the permanent dipoles of the NH3 ligands also fit the predictions.