Surface active phosphines for catalysis under two-phase reaction conditions. P(menthyl) [(CH2)8C6H4-p-SO3Na]2 and the hydroformylation of styrene

Supramolecular catalysis. Part 2: artificial enzyme mimics

The design of artificial catalysts able to compete with the catalytic proficiency of enzymes is an intense subject of research. Non-covalent interactions are thought to be involved in several properties of enzymatic catalysis, notably (i) the confinement of the substrates and the active site within a catalytic pocket, (ii) the creation of a hydrophobic pocket in water, (iii) self-replication properties and (iv) allosteric properties. The origins of the enhanced rates and high catalytic selectivities associated with these properties are still a matter of debate. Stabilisation of the transition state and favourable conformations of the active site and the product(s) are probably part of the answer. We present here artificial catalysts and biomacromolecule hybrid catalysts which constitute good models towards the development of truly competitive artificial enzymes.

New rhodium(III) and ruthenium(II) water-soluble complexes with 3,5-diaza-1-methyl-1-azonia-7-phosphatricyclo[3.3.1.1(3,7)]decane

The new water-soluble phosphine complexes of rhodium(III), [RhI(4)(mtpa)(2)]I (1), and ruthenium(II), [RuI(4)(mtpa)(2)].2H(2)O (2) and [RuI(2)(mtpa)(3)(H(2)O)]I(3).2H(2)O (3) (mtpa = 3,5-diaza-1-methyl-1-azonia-7-phosphatricyclo[3.3.1.1(3,7)]decane cation), have been prepared in the reactions of RhCl(3).3H(2)O and RuCl(3).3H(2)O in water in the presence of phosphine and potassium iodide. Properties and reactivity of the complexes have been investigated using (1)H and (31)P NMR and IR spectroscopies. The complexes have also been structurally characterized by single crystal X-ray diffraction studies. The compounds [RhI(4)(mtpa)(2)]I and [RuI(4)(mtpa)(2)].2H(2)O are zwitterionic octahedral complexes. The compounds were tested as catalysts for two-phase hydroformylation of 1-hexene and hydrogenation of cinnamaldehyde. Complex 1 is a selective catalyst for reduction of the C=C bond while complexes 2 and 3 selectively hydrogenate the C=O bond.