Magnetic Anisotropy of a High-Spin Octanuclear Nickel(II) Complex with a meso-Helicate Core

Abstract

The octanickel(II) cluster 2b has been synthesized from the novel ferromagnetically coupled dinickel(II) metallacryptand 1b assembled from the m-phenylene-bis(oxamate) ligand. Complex 2b exhibits a dimer-of-tetramers structure, with two oxamate-bridged propeller-shaped tetranuclear units connected through three meta-substituted phenylenediamidate bridges, giving a metallacryptand core of the meso-helicate type. Complex 2b behaves as a ferromagnetically coupled dimer of two S=2 Ni(II)4 units with appreciable magnetic anisotropy.

Supramolecular coordination chemistry of aromatic polyoxalamide ligands: A metallosupramolecular approach toward functional magnetic materials

“…c J and J are the exchange coupling parameters through the oxamato and phenylene bridges, This situation contrasts to that found in the Ni II 8 MOCs (L = 2a and 2c; L = dipn) which possesses a "dimer-of-tetramers" doublestar structure of reduced C 1 molecular symmetry due to the presence among the six peripheral metal atoms of both mer and fac isomers with respect to the conformation of the tridentate blocking ligand dipn (Fig. 16a) [33]. In this other case, the Ni II 2 metallacryptand core acts as a FCU between the Ni II 4 star entities (S A = S B = 3S Ni -S Ni = 2) to give a ground nonet spin state (S = S A + S B = 4) for the Ni II 8 molecule (Table 2) [33].…”

“…16a) [33]. In this other case, the Ni II 2 metallacryptand core acts as a FCU between the Ni II 4 star entities (S A = S B = 3S Ni -S Ni = 2) to give a ground nonet spin state (S = S A + S B = 4) for the Ni II 8 molecule (Table 2) [33].…”

A Metallacryptand‐Based Manganese(II)–Cobalt(II) Ferrimagnet with a Three‐Dimensional Honeycomb Open‐Framework Architecture

“…[1][2][3][4] Discrete zero-dimensional polynuclear coordination compounds as well as infinite one-, two-, or three-dimensional coordination polymers, also known as metal-organic frameworks (MOFs), [5] are included in this category. [9][10][11][12] In particular, the triple-stranded dinuclear cobalt(II) complex [Co 2 -(mpba) 3 ] 8À [mpba = 1,3-phenylenebis(oxamato)] enables the formation of double-propeller octanuclear coordination compounds with a metallacryptand core when acting as a hexakis(bidentate) ligand (Scheme 1, left). Such multidimensional species are of great importance in the so-called "bottom-up" approach to molecular magnetic materials, particularly the low-dimensional single-molecule (SMMs) or single-chain (SCMs) magnets and the higher-dimensionality moleculebased magnets, all of which have potential applications in information storage and processing nanotechnology.…”

“…The binding of these heterochiral meso-helicate-type Co II 2 metallacryptands to axially distorted octahedral trans-diaqualithium(I) ions through the two cis carbonyl-oxygen atoms of the oxamato groups [Li1 À O1 = 1.962(9), Li(1) À O(2) = 2.039 (11), and Li(1)ÀO(1w) = 2.65(2) ] leads to the expected 3D honeycomb framework ( Figure 2). Such outward coordination has rarely been exploited for metallacryptands (helicates and meso-helicates), although inward coordination to give metallacryptates is commonly observed.…”

“…[6][7][8] Our strategy in this field is based on combining mono-, di-, and trinuclear late 3d transition metal complexes with a novel family of aromatic polyoxamato ligands as building blocks for the rational design of oxamato-bridged high-nuclearity coordination compounds and high-dimensionality coordination polymers with interesting magnetic properties. [9][10][11][12] In particular, the triple-stranded dinuclear cobalt(II) complex [Co 2 -(mpba) 3 ] 8À [mpba = 1,3-phenylenebis(oxamato)] enables the formation of double-propeller octanuclear coordination compounds with a metallacryptand core when acting as a hexakis(bidentate) ligand (Scheme 1, left). Such coordination compounds could constitute the basic structural unit for the construction of 3D open-frameworks with a "honeycomb" architecture and a (6,4) of their sorption ability toward solvent molecules and gases is also provided.…”