The synthesis and characterisation of a large family of hexametallic [Mn(III)(6)] Single-Molecule Magnets of general formula [Mn(III)(6)O(2)(R-sao)(6)(X)(2)(sol)(4-6)] (where R = H, Me, Et; X = (-)O(2)CR' (R' = H, Me, Ph etc) or Hal(-); sol = EtOH, MeOH and/or H(2)O) are presented. We show how deliberate structural distortions of the [Mn(3)O] trinuclear moieties within the [Mn(6)] complexes are used to tune their magnetic properties. These findings highlight a qualitative magneto-structural correlation whereby the type (anti- or ferromagnetic) of each Mn(2) pairwise magnetic exchange is dominated by the magnitude of each individual Mn-N-O-Mn torsion angle. The observation of magneto-structural correlations on such large polymetallic complexes is rare and represents one of the largest studies of this kind.

The synthesis and characterisation of a large family of trimetallic [Mn(III)(3)] Single-Molecule Magnets is presented. The complexes reported can be divided into three categories with general formulae (type 1) [Mn(III)(3)O(R-sao)(3)(X)(sol)(3-4)] (where R = H, Me, (t)Bu; X = (-)O(2)CR (R = H, Me, Ph etc); sol = py and/or H(2)O), (type 2) [Mn(III)(3)O(R-sao)(3)(X)(sol)(3-5)] (where R = Me, Et, Ph, (t)Bu; X = (-)O(2)CR (R = H, Me, Ph etc); sol = MeOH, EtOH and/or H(2)O), and (type 3) [Mn(III)(3)O(R-sao)(3)(sol)(3)(XO(4))] (where R = H, Et, Ph, naphth; sol = py, MeOH, beta-pic, Et-py, (t)Bu-py; X = Cl, Re). We show that deliberate structural distortions of the molecule can be used to tune the observed magnetic properties. In the crystals the ferromagnetic triangles are involved in extensive inter-molecular H-bonding which is clearly manifested in the magnetic behaviour, producing exchange-biased SMMs. These interactions can be removed by ligand replacement to give "simpler" SMMs.

The synthesis and magnetic characterisation of a series of bis-μ-alkoxide bridged Mn(III) dinuclear complexes of general formula [Mn(III)(2)(μ-OR)(2)(biphen)(2)(ROH)(x)(L)(y)] (where R = Me, Et; H(2) biphen = 2,2'-biphenol and L = terminally bonded N-donor ligand) is described, doubling the literature basis set for this type of complex. Building on these findings we have categorised all known μ-OR bridged Mn(III) dinuclear complexes into one of three classifications with respect to their molecular structures. We have then employed DFT and MO calculations to assess all potential magneto-structural correlations for this class of compound in order to identify the structural requirements for constructing ferromagnetic family members. Our analysis indicates that the most influential parameter which governs the exchange interaction in this class of compounds is the relative orientation of the JT axes of the Mn(III)  atoms. A perpendicular orientation of the JT axes leads to a large ferromagnetic contribution to the exchange. These results also suggest that a large ferromagnetic interaction and a large anisotropy are unlikely to co-exist in such structural types.

The use of derivatised salicylaldoximes in manganese chemistry has led to the synthesis of a family of approximately fifty hexanuclear ([Mn(III)(6)]) and thirty trinuclear ([Mn(III)(3)]) Single-Molecule Magnets (SMMs). Deliberate, targeted structural distortion of the metallic core afforded family members with increasingly puckered configurations, leading to a switch in the pairwise magnetic exchange from antiferromagnetic to ferromagnetic. Examination of both the structural and magnetic data revealed a semi-quantitative magneto-structural correlation, from which the factors governing the magnetic properties could be extracted and used for predicting the properties of new family members and even more complicated structures containing analogous building blocks. Herein we describe an overview of this extensive body of work and discuss its potential impact on similar systems.