Synthesis, structure and magnetic properties of a family of complexes, containing {CoII2DyIII} pivalate core, and pentanuclear CoII4DyIII derivative

A series of new CoII-DyIII complexes with metal-organic core {Co2Dy(NO3)(Piv)6} was prepared by self-assembly reactions or step-by-step assembling. [Co2Dy(NO3)(Piv)6(MeCN)2] was used as starting compound for synthesis of trinuclear analogue [Co2Dy(NO3)(Piv)6(py)2] and pentanuclear complex [{Co2Dy(NO3)(Piv)6}{CoL(Piv)(H2O)}2](NO3)2 (L = 2,6-bis(2-pyridyl)-4-(4-pyridyl)pyridine). Change of LnIII coordination polyhedra distortion depending on coordination environment and temperature was analyzed in a series of coordination compounds with MII2LnIII cores and close analogues. The distortion of the LnIII ion polyhedron depends both on the composition of the compound and temperature, temperature increase favors to D2d geometry of LnIII coordination polyhedron. Magnetic properties of the complexes with CoII2DyIII cores were analyzed taking into account anisotropy of CoII and DyIII ions. The compounds with similar polynuclear cores, containing diamagnetic LaIII and isotropic GdIII - [Co2Ln(Piv)6(NO3)(MeCN)2] (Ln = La, Gd) - were studied for evaluation of CoII magnetic anisotropy parameters in order to minimize overparametrization in magnetic properties fitting for Co2Dy systems. It was found that magnetic properties of all complexes in this study were mainly governed by the magnetic properties of isolated ions.

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