Isomorphous <i>Catena</i> Transition Metal Squarates [<i>M</i>^II(C₄O₄)(dmso)₂(OH₂)₂] (<i>M</i> = Co, Mn) and Magnetic Investigation into their Solid Solution <i>M</i> = Co<i>_x</i>Mn_1–<i>x</i>

Abstract

Abstract The crystal structures of two new isomorphous transition metal squarato complexes [ M II (C 4 O 4 )(dmso) 2 (OH 2 ) 2 ] [ M II = Co II (3d 7 ), Mn II (3d 5 ); dmso = dimethylsulfoxide] and their magnetic properties are reported. The compounds feature two symmetrically independent chains, in which 1,3‐bridging squarato ligands connect cations in distorted octahedral surroundings of pseudo‐symmetry D 4 h . From an equimolar solution of CoCl 2 · 6H 2 O and MnCl 2 · 2H 2 O a mixed‐metal coordination polymer crystallizes; it represents a solid solution and adopts the same structure as the corresponding monometallic compounds. The results of the diffraction experiment unambiguously proof the presence of both Co II and Mn II cations in either independent site albeit no precise ratio between the metal cations involved may be deduced from these findings. The difference in the magnetic properties between Co II and Mn II cations in the given ligand field has allowed us to establish their ratio in the solid solution more reliably than by X‐ray diffraction: Accounting for ligand field potential and spin‐orbit coupling of Co II and regarding Mn II as a pure spin system, the calculations yielded a fraction of 73 % Co II in the mixed‐metal polymer. With respect to superexchange effects only weak antiferromagnetic interactions have been detected for the three coordination polymers.