Synthesis, structure, magnetism, and electrochemical properties of a linear pentanuclear Ni5 compound derived from an oligo-α-pyridylamino ligand: Ni5(μ-dmpdda)4(NCS)2
Journal
Journal of Coordination Chemistry
Journal Volume
62
Journal Issue
18
Pages
2974-2982
Date Issued
2009
Author(s)
Abstract
The synthesis, crystal structures, electrochemical, and magnetic properties of a linear pentanuclear Ni5 compound derived from an oligo-α-pyridylamino ligand, [Ni5(μ-dmpdda)4(NCS)2] [dmpdda-H2 = N,N′-di(4-methylpyridin-2-yl)pyridine-2,6-diamine], are reported. Ni5(μ-dmpdda)4(NCS)2 involve a Ni5 linear chain unit with all of the Ni-Ni-Ni angles being nearly 180°, terminated by two axial ligands. The pentanuclear linear metal chain is helically wrapped by four syn-syn-syn-syn type dmpdda2- ligands. There are two types of Ni-Ni distances in this complex. Terminal Ni-Ni distances bonded with the axial ligand are longer (2.377 Å); the inner Ni-Ni distances are short at 2.2968 Å. Terminal Ni(II) ions bonded with the axial ligands are square-pyramidal (NiN4NCS) with long Ni-N bonds (2.092 Å), consistent with a high-spin Ni(II) configuration. The inner three Ni(II) ions have short Ni-N (1.901-1.925 Å) bond distances, consistent with a square planar (NiN4), diamagnetic arrangement of a low-spin Ni(II) configuration. This compound exhibits magnetic behavior similar to [Ni5(μ-tpda)4(NCS)2], indicating an antiferromagnetic interaction of two terminal high-spin Ni(II) ions. © 2009 Taylor & Francis.
Type
journal article