Accession Number : ADA322375

Title :   Optical Memory Systems Based on Transition Metal Photochromism: Photodisproportionation of d sup 1-d sup 1 Dimers with Linear Oxo Bridges.

Descriptive Note : Final rept. 1 May 90-30 Jun 93,

Corporate Author : PITTSBURGH UNIV PA DEPT OF CHEMISTRY

Personal Author(s) : Cooper, N. J.

PDF Url : ADA322375

Report Date : 17 FEB 1997

Pagination or Media Count : 8

Abstract : This project explored the potential as photochromic substrates for optical memory systems of transition metal complexes in which two d sup 1 transition metal centers are spin paired through a linear oxo bridge. The project was based on the discovery of a dinuclear W(V) tungstenocene derivative in which irradiation into the strong visible region absorbance associated with the d sup 1-d sup 1 oxo bridged chromophore led to marked photochromism following photodisproportionation to a 1:1 mixture of d sup 0 and d sup 2 complexes. Examination of the large class of d sup 1-d sup 1 oxo bridged dimers containing MV2O34+ (M = Mo, W) cores stabilized by bis-chelate dithiocarboxylate-type ligands S2EXn led to the observation that dibenzyldithiocarbamates complexes of these cores undergo an analogous thermally reversible photochromic disproportionation, but dithiophosphate complexes undergo irreversible wavelength dependent photo-bleaching; the complexes are not themselves photoactive but are destroyed through photolysis of d sup 0 products of thermal disproportionation products. Both dithiocarbamate and xanthate complexes of the MoV2O3(4+) core are fluxional, participating in a process in which there is rapid intramolecular exchange of bridging and terminal oxo groups.

Descriptors :   *TRANSITION METALS, *OPTICAL STORAGE, *DIMERS, *DISPROPORTIONATION, *PHOTOCHROMISM, STABILIZATION, THERMAL PROPERTIES, LINEAR SYSTEMS, OPTICAL EQUIPMENT, CORES, PHOTOLYSIS, MOLYBDENUM, SUBSTRATES, REVERSIBLE, LIGANDS, VISIBLE SPECTRA, IRRADIATION, HEAT, TUNGSTEN, VANADIUM, SPIN STATES, METAL COMPLEXES, PHOTOCHROMIC MATERIALS.

Subject Categories : Polymer Chemistry
      Organic Chemistry
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE