Copper and copper-manganese 1D coordination polymers: Synthesis optimization, crystal structure and preliminary studies as catalysts for Baylis–Hillman reactions

Abstract

This work reports the influence of experimental parameters (pH and counter-ion) in the synthesis of the 1D coordination polymer [Cu(IDA)(H2O)2]n (IDA = iminodiacetate), named here Cu-IDA. Copper-manganese bimetallic coordination polymers were also obtained by isomorphic replacement into Cu-IDA structure, with different molar ratio of Cu2+ and Mn2+ ions, denoted here as Cu/Mn-IDA (0.9/0.1; 0.7/0.3 and 0.5/0.5). New coordination polymers are isostructural to Cu-IDA and amounts of manganese atoms inserted into crystalline structure were evaluated by single-crystal X-ray diffraction and Rietveld refinement. All coordination polymers obtained were also characterized by infrared absorption spectroscopy and thermogravimetric analysis. Homometallic and bimetallic compounds were evaluated as catalysts for Baylis-Hillman reaction with yields and reaction times comparable or superior to those in the literature. Compounds containing manganese cations shows higher catalytic performance, especially Cu/Mn-IDA (0.9/0.1) with yield 91% in 5 h of reaction. Results also indicate an important role played by the metallic centre in the catalytic mechanism.