Spectroscopy and Photochemistry of Polynuclear Metal Complexes

Citation

Maverick, Andrew William (1982) Spectroscopy and Photochemistry of Polynuclear Metal Complexes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/PBEA-8W62. https://resolver.caltech.edu/CaltechETD:etd-03092005-130854

Abstract

The photochemical and spectroscopic properties of two classes of polynuclear metal complexes have been studied.

Molybdenum and Tungsten Cluster Halides: The cubic ions Mo₆Cl₁₄^2-, Mo₆Br₁₄^2-, and W₆Cl₁₄^2- are luminescent, with lifetimes approaching 200 μs in solution at room temperature. The luminescent excited state of Mo₆Cl₁₄^2- is probably associated with a transition localized on the central Mo₆ core. Both this excited state and the corresponding ground state undergo facile one electron oxidation. These features make the cluster ions attractive for experiments in photochemical energy storage. Also discussed is evidence from magnetic and spectroscopic studies bearing on the electronic structures of the cluster ions.

Rhodium Isocyanide Complexes: Various thermal and photochemical reactions in the system Rh₂b₄²⁺ - Rh₄b₈⁶⁺ - Rh₂b₄⁴⁺ (b = 1,3-diisocyanopropane) have been examined. The possibility of photocatalytic hydrogen production sensitized by Rh₂b₄²⁺ and Rh₄b₈⁶⁺, previously shown to produce H₂ stoichiometrically on irradiation in strongly acidic solution, was explored. Experiments were also conducted with Rh₂(TMB)₄²⁺ (TMB = 2,5-diisocyano-2,5-dimethylhexane) in the hopes of accomplishing similar energy storage reactions. The equilibria in acidic aqueous solution involving these species as well as oligomers of intermediate oxidation state were also studied. Kinetic studies of the reduction of Rh₂b₄⁴⁺ by H₂ and of thermal and photochemical oxidation of Rh₄b₈⁶⁺ by O₂ were inconclusive.

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