Synthesis, characterization and olefin/CO exchange reactions of pyrazolylborato complexes of copper(i)

Abstract

New bis(pyrazolyl)borato olefin complexes of copper(I) of general formula Cu[BH₂(3,5-(CF₃)₂Pz)₂](olefin) have been prepared (olefins: coe = cyclooctene, van = 4-vinylanisole, clsty = 4-chlorostyrene, tevs = triethylvinylsilane, fn = fumaronitrile). The structures of Cu[BH₂(3,5-(CF₃)₂Pz)₂](L), L = coe, van, tevs, fn, have been determined by X-ray diffraction methods. Considering the two N atoms of the bis(pyrazolyl)borate ligand and the midpoint of the C–C double bond of the coordinated olefin, the compounds with L = coe, van and tevs contain a copper atom in a trigonal planar coordination. A coordination polymer with N-coordinated fumaronitrile and tetrahedral coordination of copper atoms is obtained in the case of L = fn. The carbonylation reactions of Cu[BH₂(3,5-(CF₃)₂Pz)₂](olefin) (olefin = coe, clsty, van, tevs), Cu[BH₂(3,5-(CF₃)₂Pz)₂](olefin) + CO ⇆ Cu[BH₂(3,5-(CF₃)₂Pz)₂](CO) + olefin, have been studied gas volumetrically and the thermodynamical parameters of the equilibria for the displacement of the coordinated olefin by carbon monoxide have been determined. These data for copper(I) are compared with those reported in the literature.