One-dimensional Cu(I) camphor hydrazone polymers: Structure and catalytic properties

Complexes of general formula [{CuX}2(YNC10H14O)] (X = Cl; Y = NHMe, NH2 or X = Br; Y = NH2) were synthesised from camphor hydrazone ligands (YNC10H14O) by reaction with the suitable copper(I) halide. Structural analysis by X-rays performed on a red crystal of [{CuCl}2(Me2NNC10H14O)] revealed that the complex is a one-dimensional copper polymer formed by two rather different copper units bridged by chloride. One of the copper units displays a tetrahedral geometry while the other is linear. Although the geometries and neighbourhoods of the two copper units are very different the oxidation state of the metal is the same, i.e. Cu(I) as corroborated by magnetic and electrochemical measurements.The ability of [{CuCl}2(Me2NNC10H14O)] to promote the activation of 4-pentyn-1-ol towards cyclization was studied under homogeneous or heterogeneous experimental conditions. The best results were obtained under homogeneous conditions at 40 °C.

Graphical abstractThe one-dimensional polymer structure of [{CuCl}2(Me2NNC10H14O)] bearing the unique linear and tetrahedral Cu(I) metal centres bridged by halide supports the polymer character of complexes [{CuX}2(YNC10H14O)] (X = Cl; Y = NHMe, NH2 or X = Br; Y = NH2). [{CuCl}2(Me2NNC10H14O)] catalyses the conversion of 4-pentyn-1-ol into 2-methoxy-2-methyl-tetrahydrofuran.Figure optionsDownload full-size imageDownload as PowerPoint slide