A Linear Tetranuclear Single-Molelcule Magnet of Mn^II₂Mn^III₂ with the Anion of 2-(Hydroxymethyl)pyridine

Abstract

A tetranuclear manganese complex, [Mn(4)(hmp)(6)(N(CN)(2))(4)(H(2)O)(2)] [1; Hhmp = 2-(hydroxymethyl)pyridine; N(CN)(2)(-) = dicyanamide anion], was synthesized and characterized by single-crystal X-ray diffraction, bond valence sum calculations, IR spectra, elemental analysis, and magnetic measurements. The structure of 1 consists of a linear [Mn(II)(2)Mn(III)(2)] core formed by six hmp(-) groups linking Mn(II/III) ions. Magnetic studies show that 1 behaves as a single-molecule magnet with ferromagnetic coupling between the metal centers.

Synthesis, crystal structure and magnetic properties of a trinuclear phenolate bridged manganese complex containing Mn(ii)–Mn(iii) ions

“…Some of them exhibit ferromagnetic couplings, 33,38,39 others are antiferromagnetic. 33,[40][41][42][43] In all these complexes the super-exchange interactions have been found to be weak, like in 1, with values which range À7 to +3.94 cm À1 . 32 A few attempts have been done in order to nd some correlations between the magnetic couplings constants and some structural parameters, 33 however the large number of singly occupied orbitals, the geometry of the Mn ions, the occurrence of interactions through different s and p magnetic exchange pathways and the diversity of bridges involved has made, at least up to now, impossible to nd a clear structural parameter, or set of parameters, directly correlated to the magnetic coupling.…”

Manganese, technetium and rhenium

“…A tetranuclear single-molecule magnet has been prepared that contains a linear [Mn II 2 Mn III 2 ] core with ferromagnetic coupling between the metal centres. 28 Elsewhere a novel 1D coordination polymer has been synthesised that contains Mn III 6 cores bridged by bithiophene dicarboxylato ligands. 29 The compound behaves as a single-molecule magnet with no noticeable magnetic interactions between the Mn 6 clusters through the bridging ligands.…”

New mixed-valence MnII4MnIV clusters from an unusual ligand transformation

“…Many clusters from these reactions, and analogous ones using bulkier derivatives of these chelates [23][24][25][26][27][28][29][30], have displayed interesting structures and/or magnetic properties, and some have turned out to be new single-molecule magnets (SMMs). The latter owes much to the propensity of bridging hmpto lead to ferromagnetic (F) coupling [18,21,[31][32][33][34], as indeed do a number of oximate chelates in Mn cluster chemistry [20,35,36]. In addition, some of the Mn 3 SMMs have also proven excellent precursors for making supramolecular aggregates or high nuclearity manganese clusters [37][38][39][40].…”