Linked Nickel Metallacrowns from a Phosphonate/2-Pyridyloximate Blend of Ligands: Structure and Magnetic Properties

Abstract

In the present work, four new NiII clusters with nuclearities ranging between Ni4 and Na2Ni8 were synthesized, employing the versatile ligand phenylphosphonate and 6-methylpyridylaldoximate as the coligand. Crystallographic data show that the tetranuclear complex [Ni 4 (6-MepaoH)4(PhPO3)2(OH)2(MeOH)4](OH)2 (1) consists of two dimers linked by phosphonate bridges, whereas [Cs2Ni6(6-Mepao)6(PhPO3)3(OH)2(H2O)8] (2), Cs[Ni8(6-MepaoH)6(6-Mepao)6(PhPO3)3](ClO4)5 (3), and [Ni8Na2(BzO)6(6-Mepao)6(PhPO3)3] (4) are built from phosphonato-linked {Ni3(6-Mepao)3} metallacycles. The [9-MCNiII(6‑Mepao)-3] fragments in 2−4 show the unusual coordination of additional Cs+, Na+ , and/or NiII cations. Direct-current magnetic measurements were carried in the 300−2 K range. Analysis of the experimental data revealed a complex response with strong antiferromagnetic interactions mediated by the oximato bridges and weak interactions mediated by the phosphonate ones.