Photoreactions of the triruthenium cluster HRu3(CO)10 (.mu.-COCH3). Isomerization of the bridging alkylidyne ligand and competing ligand substitutions

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Title: Photoreactions of the triruthenium cluster HRu3(CO)10 (.mu.-COCH3). Isomerization of the bridging alkylidyne ligand and competing ligand substitutions
Author: Friedman, Alan; Ford, Peter
Abstract: Irradiation of the title compound HRu3(CO)10(u-COCH3) (A) in hydrocarbon solution under CO leads to the formation of the bridging u,n2 acyl isomer HRu3(CO)10(u,n2-C(O)CH3) (B). Quantum yields for isomerization phi-i were wavelength dependent ranging from at 405-nm excitation to about 0.05 at 313-nm excitation under Pco 1.0 atm. In addition, over the range 0-1.0 atm, the phi-i values proved to be linearly dependent on Pco despite the absence of a stoichiometric requirement for CO in the isomerization. A key observation was that photoisomerization of A 13C labeled specifically at the bridging alkylidyne carbon, i.e., HRu3(CO)10(u -13COCH3), gives B specifically labeled at the bridging acyl carbon, i.e., HRu3(CO)10(u,n2-13C(0)CH3), with no evidence of scrambling of the label with other carbons in the complex. Photolysis in the presence of ‘13CO or other added ligands demonstrated the lability of the cluster coordinated carbonyls to photosubstitution reactions. The quantum yield for photosubstitution phi s follows the same wavelength dependence as does phi i, and it is proposed that the two processes result from competitive decay pathways of common intermediates. Limiting quantum yields for photosubstitution are about 0.25. A mechanism for these reactions related to that proposed previously for the photofragmentation of the parent triruthenium cluster Ru3(CO)12 is discussed. Prolonged 313-nm irradiation of HRu3(CO)10(u,n2-C(O)CH3) under CO leads to cluster fragmentation and the formation of Ru(CO)5 plus acetaldehyde.
Record URI: http://hdl.handle.net/1850/2316
Publishers URL: http://dx.doi.org/10.1021/ja00184a024
Date: 1989-01-18

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