Spin Control in Oxamato-Based Manganese(II)–Copper(II) Coordination Polymers with Brick-Wall Layer Architectures

Two new heterobimetallic manganese(II)–copper(II) coordination polymers of formulas [Mn2Cu2(Me3mpba)2(H2O)6]·8H2O (1) and [Mn2Cu2(Me4ppba)2(H2O)6]·8H2O (2) [Me3mpba = 2,4,6-trimethyl-N,N′-1,3-phenylenebis(oxamate) and Me4ppba = 2,3,5,6-tetramethyl-N,N′-1,4-phenylenebis(oxamate)] have been synthesized following a molecular-programmed self-assembly method from the corresponding dicopper(II) complexes acting as metalloligands toward MnII ions. 1 and 2 consist of neutral MnII2CuII2 layers with a brick-wall structure made up of oxamato-bridged MnIICuII chains connected through double meta- (1) and para-substituted (2) permethylated phenylene spacers. Overall magnetic (1) and nonmagnetic (2) layer ground states result from the ferro- and antiferromagnetic interchain interactions between the oxamato-bridged MnIICuII ferrimagnetic chains across m- and p-phenylene spacers, respectively. Interestingly, compound 1 exhibits a long-range ferromagnetic ordering with a rather high Curie temperature (TC) of 20.0 K.