Synthesis, structure, and magnetic properties of new pyridonate–pivalate nickel(II) complex, [Ni11(OH)2(mhp)8(Piv)10(HCO2)2(H2O)2(Hmhp)2(HPiv)2] (mhp = 6-methyl-2-pyridonate), containing formate bridges

The undecanuclear complex [Ni11(OH)2(mhp)8(Piv)10(HCO2)2(H2O)2(Hmhp)2(HPiv)2] (2, where Piv is the anion of pivalic acid) containing 6-methyl-2-pyridonate, pivalate and formate anions have been obtained as a result of interaction of trimethylacetate (or pivalate) nickel(II) complex [Ni9(OH)6(Piv)12(HPiv)4] with 2-hydroxy-6-methylpyridine in dimethoxyethane, containing about 0.50% of methyl formate. The structure of 2 is determined using X-ray diffraction analysis and its magnetic susceptibility is measured between 2 and 300 K. It is shown that complicated low-temperature magnetic behavior of 2 is due to combined influence of competing ferro- and antiferromagnetic interactions, zero-field splitting effect and anisotropic exchange interactions in the Ni11 clusters.