Ruthenium complexes as potential aqueous romp catalysts

Abstract

The research described herein relates to studies into the Aqueous Ring-Opening Metathesis Polymerisation (ROMP) of bicyclic monomers using ruthenium complex catalysts. Two monomers were synthesised for the purpose of these studies, namely exo, exo-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid (7-oxanorbornenedicarboxylic acid) and exo, exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid (norbornene dicarboxylic acid).
A number of ruthenium complexes were synthesised, amongst them a novel complex containing the water soluble phosphine ligand trist(hydroxymethyl)phosphine P(CH₂OH)₃. Its synthesis and characterisation are described and its physical properties compared and contrasted to analogous compounds of platinum and palladium. Its peculiar properties are ascribed to a trans-placement of the phosphine ligands.
Dilatometry was investigated as a technique for the acquisition of kinetic data from aqueous metathesis reactions. For the attempted polymerisation of 7-oxanorbonenedicarboxylic acid the results are explained in terms of a reverse Diels-Alder reaction of the monomer.
The reaction between Ru(CO)Cl₂(H₂O) and 7-oxanorbonenedicarboxylic acid was monitored using UV/Vis spectrometry and kinetic data retrieved. The data are explained in terms of a two stage reaction consisting of consecutive first order processes.The reaction between 7-oxanorbornenedicarboxylic acid and Ru(CO)Cl₂(H₂O) or Ru(P(CH₂OH)₃)₃Cl₂ was found to produce fumaric acid as one of the major products. This reaction is previously unreported in the literature and a mechanism is proposed.