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One-electron reduction of the complexes (Re(Br)(CO)3(R'-DAB)) in nPrCN has led to the establishment of an equilibrium between the radical anions and the solvento radical. The Re-Br bond becomes more stable with the electron-withdrawing character of R' and with decreasing temperature. Reduction of the radicals can be undertaken in a subsequent one-electron step to give the five-coordinate anions, together with the six-coordinate anions, as the minor products.

The lowest energy electronic transition of Re(X)(CO)3(alpha-diimine) (X = Cl, Br, I; alpha-diimine = bpy, iPr-PyCa, iPr-DAB) changes from Re to alpha-diimine (MLCT) to X to alpha-diimine (XLCT) on moving from Cl to Br. Resonance Raman spectra and time-resolved absorption and emission spectroscopy show that the change in excited state is attributed to an irregular mixing of the d(sub pi)(Re) and p(sub pi)(X) orbitals. The emission from the XLCT excited state exhibits a longer lifetime due to the slow nonradiative decomposition to the ground state.

Time-resolved UV-vis absorption spectroscopy and nano-second flash photolysis analyze the photoreactions of three (CO)(5)ReMn(CO)(3) (alpha-diimine) complexes at different temperatures and pressures. Primary photoprocess in the metal-to-ligand charge-transfer excitation of these complexes is a fast CO dissociation from Mn center. High reactivities of these complexes are due to an available Mn coordination site and a weak Re-M bond.

Raman microscopy is applied to monitor the preparation of shaped Mo/Al2O3 catalysts. It is illustrated that the time-resolved in situ Raman microscopy can be used to study the physicochemical processes during the preparation of supported catalysts.

The time resolved UV-Vis and IR spectroscopies of Re(bz)(CO)3(iPr-DAB), where Bz is benzyl and iPr-DAB is N,N'-diisopropyl-1,4-diazabutadiene, detect the reactive sigma-pi* excited state. During the photochemical homolysis of the Re-Bz bond, this excited state acts as an intermediate. The complex after excitation to its MLCT visible absorption band suffers homolysis. The spin-triplet nature of the sigma-pi* excited state and small excited state distortion makes it highly stable.

Describes the reduction routes of inorganic complexes and metal-alkyl complexes, using data obtained from IR and UV-vis spectroelectrochemical measurements and cyclic voltammetry at variable temperatures. Materials and preparations; IR spectral changes in the carbonyl stretching region during the reduction; Establishment of a one-electron reduction.

Raman microscopy has been applied to study the preparation of shaped Mo/Al2O3 catalysts. The speciation of different Mo complexes over γ-Al2O3 support bodies was followed in time after pore volume impregnation with aqueous solutions containing different Mo complexes. The addition of NO3 to the impregnation solutions allows for a quantitative Raman analysis of the distribution of different complexes over the catalyst bodies as this ion can be used as an internal standard. After impregnation with an acidic ammonium heptamolybdate (AHM) solution, the strong interaction between Mo7O246- and Al2O3 results in slow transport of this complex through the support and extensive formation of Al(OH)6Mo6O183- near the outer surface of the support bodies. This may be prevented by decreasing the interaction between Mo and Al2O3. In this way, transport is facilitated and a homogeneous distribution of Mo is obtained on a reasonable time scale. A decrease in interaction between Mo and Al2O3 can be achieved by using alkaline impregnation solutions or by the addition of complexing agents, such as citrate and phosphate, to the impregnation solution. In general, time-resolved in situ Raman microscopy can be a valuable tool to study the physicochemical processes during the preparation of supported catalysts. [ABSTRACT FROM AUTHOR]