Structural diversity of Mn(II) and Cu(II) complexes based on 2-carboxyphenoxyacetate linker: Syntheses, conformation comparison and magnetic properties

Four new binary complexes with 2-carboxyphenoxyacetic acid ligand (2-H2cpa), namely [Mn(2-cpa)(H2O)3] (0D-Mn), [Cu(2-cpa)(H2O)3] (0D-Cu), [Mn(2-cpa)(H2O)]n (1D-Mn) and [Cu(2-cpa)(H2O)]n (2D-Cu), have been successfully prepared and systematically characterized. Structure analyses indicated that 0D-Mn and 0D-Cu are isomorphous mononuclear species in which the 2-carboxyphenoxyacetate (2-cpa) is a tridentate chelate anionic ligand. 1D-Mn is a 1D zigzag chain structure formed by the tetradentate bridging chelate-μ2 coordination pattern of 2-cpa connecting adjacent MnII ions. While 2D-Cu is a 2D corrugated (4,4)-connected layer and 2-cpa adopts pentadentate double bridging chelate-μ3 coordination mode in it. The different synthetic conditions, crystal structures and conformation of 2-cpa in the above compounds have been carefully analyzed and the results revealed that the synthetic conditions and flexible conformation of 2-cpa may be responsible for the structural diversity of binary 2-cpa metal complex system. In addition, the magnetic measurements showed that between the neighbouring metal ions there are weak ferromagnetic exchange in 0D-Mn and 0D-Cu, but antiferromagnetic coupling in 1D-Mn and 2D-Cu, respectively. Four new binary complexes 0D-Mn, 0D-Cu, 1D-Mn and 2D-Cu have been successfully prepared and characterized. The synthetic conditions and flexible conformation of 2-cpa may induce the structural diversities of them. The magnetic measurement revealed that 0D-Mn and 0D-Cu showed weak ferromagnetic exchange, while 1D-Mn and 2D-Cu displayed antiferromagnetic coupling behavior. [Display omitted] •Four new complexes based on 2-carboxyphenoxyacetate (2-cpa) have been described.•Different synthetic conditions and ligand flexibility lead to the different coordination mode of 2-cpa in them.•0D-Mn and 0D-Cu have weak ferromagnetic exchange; 1D-Mn and 2D-Cu show antiferromagnetic coupling.•This work is important supplement for binary 2-cpa metal complex system.