Synthesis, Structure, and Magnetic Properties of a Family of Complexes Containing a {CoII 2 DyIII } Pivalate Core and a Pentanuclear CoII 4 DyIII Derivative

A series of new CoII–LnIII complexes with polynuclear {Co2Ln(NO3)(Piv)6} (Ln = La, Gd, Dy; Piv = pivalate) cores were prepared by self-assembly reactions or step-by-step assembly. [Co2Dy(NO3)(Piv)6(MeCN)2] was used as the starting compound for the synthesis of the trinuclear analogue [Co2Dy(NO3)(Piv)6(py)2] (py = pyridine) and the pentanuclear complex [{Co2Dy(NO3)(Piv)6}{CoL(Piv)(H2O)}2][NO3]2 [L = 2,6-bis(2-pyridyl)-4-(4-pyridyl)pyridine]. The effects of the coordination environment and temperature on the distortion of the LnIII coordination polyhedra were analyzed for a series of coordination compounds with MII2LnIII cores and close analogues. The distortion of the LnIII polyhedron depends on both the composition of the compound and the temperature; a temperature increase favors the D2d geometry of the LnIII coordination polyhedron. The magnetic properties of the complexes with CoII2DyIII cores were analyzed with consideration of the anisotropy of the CoII and DyIII ions. The compounds containing diamagnetic LaIII and isotropic GdIII ions, [Co2Ln(Piv)6(NO3)(MeCN)2] (Ln = La, Gd), which are isostructural to the CoIIDyIII analogue, were studied to evaluate the CoII magnetic-anisotropy parameters to minimize the overparameterization of the magnetic properties in the fits for the Co2Dy systems. The magnetic properties of all complexes in this study are governed mainly by the magnetic properties of the isolated ions.