Facile synthesis of imidazolidinyl phenolate supported Dicopper(II/II) Complexes: Activation and fixation of atmospheric CO2 as MeOCO2− showing exogenous bridge modulating magnetic exchange coupling

Reaction of [Cu2(μ-L2)(μ-O2CMe)]·H2O (1·H2O) with Et4NOH in MeOH medium replaces the μ-O2CMe bridge by MeO−. Atmospheric fixation CO2 is achieved from nucleophilic attack of copper(II) bound MeO− to CO2 and formation of MeOCO2− in [Cu2(μ-L2)(μ-O2COMe)]·H2O (2·H2O). [Display omitted] •Facile synthesis of imidazolidinyl phenolate supported dicopper(II/II) complexes with multifunctional capabilities.•Dicopper(II/II) complexes serve as model systems for studying the structure.•Exhibited intriguing IR, UV–Vis, X-ray crystallographic analyses, magnetic properties, and DFT properties.•Cu2 complex fixes atmospheric CO2, forming a bridging MeOCO2 ligand, confirmed by IR spectra and crystallographic data. Two imidazolidine grafted Schiff bases H3L2 and H3L3 have been utilized to fasten the Cu2 core in four new complexes [Cu2(μ-L2)(μ-O2CMe)]·H2O (1·H2O), [Cu2(μ-L2)(μ-O2COMe)]·H2O (2·H2O), [Cu2(μ-L2)(μ-NO3)]·H2O (3·H2O) and [Cu2L3(μ-OAc)]·5H2O (4·5H2O). Room temperature solution reaction of H3L2 with Cu2(OAc)4·2H2O provided 1·H2O in good yield. Follow-up reaction of 1·H2O with Et4NOH in air replaces μ-O2CMe (acetato) bridge by MeOCO2− (monomethyl carbonato) linker in 2·H2O. Single crystal X-ray structure established the individual complexes and confirmed the fixation of atmospheric CO2. Variable temperature (2 to 300 K) magnetic susceptibility measurements recognized the antiferromagnetic exchange interactions between the adjacent copper(II) centers in complexes 2 and 3. The amount of spin–spin interactions are found to be higher for ancillary NO3− bridge (−284 cm−1) compared to the in situ transformed MeOCO2− bridged (−1.64 cm−1).