Syntheses and Structures of Nickel(0) Complexes containing the Methyl Methacrylate Monomer as Ligand

Article abstract of DOI:10.1039/DT9950002033

The reaction of 4-C8H12)2> with the industrially important monomer methyl methacrylate, CH2=C(Me)CO2Me, in the presence of 1 or 2 mol equivalents of tricyclohexylphosphine leads to the formation of 2-CH2=C(Me)CO2Me>2> 1 and 2-CH2=C(Me)CO2Me>2> 2, respectively.The crystal structures of 1 and 2 have been determined and reveal an η²-CC mode of co-ordination of the methyl methacrylate ligands, with the CO2Me groups pendant and outside the nickel co-ordination sphere.Complexes 1 and 2 represent the first structurally characterised methyl methacrylate complexes; 2 is formed as a mixture of meso and DL diastereomers in the ratio 2.34: 1.Solution NMR studies indicate that the diastereomers interconvert rapidly, via an intramolecular mechanism, which is proposed to proceed via an O-co-ordinated intermediate.Reaction of 1 with an excess of tert-butyl acrylate CH2=CHCO2(t-Bu) yields 2-CH2=CHCO2(t-Bu))2> 4, which may be prepared independently from 4-C8H12)2>,P(C6H11)3 and tert-butyl acrylate.