Stationary phases composed of sol–gel processed organometallic complexes functionalized with polyethylene glycol

Abstract

A tripodal phosphine molybdenum tricarbonyl complex has been functionalized with polyethylene glycol spacers of average chain lengths ranging from 0 to 90. Hydrolysable end groups were attached to the spacers via a platinum catalysed hydrosilylation, a Williamson ether synthesis Cl(CH₂)₃Si(OEt)₃ and an addition reaction of OCN(CH₂)₃Si(OEt)₃. The resulting complexes were sol–gel processed by two different methods with varying amounts of Si(OMe)₄ and Si(OEt)₄ as cocondensation agents. This generated organometallic/inorganic hybrid materials with characteristic features depending on the spacer length and the amount of cocondensation agent. A detailed multinuclear NMR spectroscopic investigation established the structure of the metal complexes in the polymer and revealed the cross-linking and degree of condensation of the materials. Furthermore, relaxation studies gave insight into the dynamics of the metal complexes, within the hybrid polymers. Chemistry in the interphase was performed with selected materials. The molybdenum tricarbonyl fragments were removed by a combined photochemical/oxidative method leaving the tripodal phosphine in the polymer. These polymerised phosphines served as starting materials for new rhodium and iridium complexes as reactive centres in stationary phases.