New members of the [Mn<sub>6</sub>/oxime] family and analogues with converging [Mn<sub>3</sub>] planes

<p>The synthesis, structural, and magnetic characterization of five new members of the hexanuclear oximate [Mn<sup>III</sup><sub>6</sub>] family are reported. All five clusters can be described with the general formula [Mn<sup>III</sup><sub>6</sub>O<sub>2</sub>(R-sao)<sub>6</sub>(R′-CO<sub>2</sub>)<sub>2</sub>(sol)<sub>x</sub>(H<sub>2</sub>O)<sub>y</sub>] (where R-saoH<sub>2</sub> = salicylaldoxime substituted at the oxime carbon with R = H, Me and Et; R′ = 1-naphthalene, 2-naphthalene, and 1-pyrene; sol = MeOH, EtOH, or MeCN; <i>x</i> = 0–4 and <i>y</i> = 0–4). More specifically, the reaction of Mn(ClO<sub>4</sub>)<sub>2</sub>·6H<sub>2</sub>O with salicylaldoxime-like ligands and the appropriate carboxylic acid in alcoholic or MeCN solutions in the presence of base afforded complexes <b>1</b>–<b>5</b>: [Mn<sub>6</sub>O<sub>2</sub>(Me-sao)<sub>6</sub>(1-naphth-CO<sub>2</sub>)<sub>2</sub>(H<sub>2</sub>O)(MeCN)]·4MeCN (<b>1</b>·4MeCN); [Mn<sub>6</sub>O<sub>2</sub>(Me-sao)<sub>6</sub>(2-naphth-CO<sub>2</sub>)<sub>2</sub>(H<sub>2</sub>O)(MeCN)]·3MeCN·0.1H<sub>2</sub>O (<b>2</b>·3MeCN·0.1H<sub>2</sub>O); [Mn<sub>6</sub>O<sub>2</sub>(Et-sao)<sub>6</sub>(2-naphth-CO<sub>2</sub>)<sub>2</sub>(EtOH)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>] (<b>3</b>); [Mn<sub>6</sub>O<sub>2</sub>(Et-sao)<sub>6</sub>(2-naphth-CO<sub>2</sub>)<sub>2</sub>(MeOH)<sub>6</sub>] (<b>4</b>) and [Mn<sub>6</sub>O<sub>2</sub>(sao)<sub>6</sub>(1-pyrene-CO<sub>2</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>(EtOH)<sub>2</sub>]·6EtOH (<b>5</b>·6EtOH). Clusters <b>3</b>, <b>4,</b> and <b>5</b> display the usual [Mn<sub>6</sub>/oximate] structural motif consisting of two [Mn<sub>3</sub>O] subunits bridged by two O<sub>oximate</sub> atoms from two R-sao<sup>2−</sup> ligands to form the hexanuclear complex in which the two triangular [Mn<sub>3</sub>] units are parallel to each other. On the contrary, clusters <b>1</b> and <b>2</b> display a highly distorted stacking arrangement of the two [Mn<sub>3</sub>] subunits resulting in two converging planes, forming a novel motif in the [Mn<sub>6</sub>] family. Investigation of the magnetic properties for all complexes reveal dominant antiferromagnetic interactions for <b>1</b>, <b>2,</b> and <b>5</b>, while <b>3</b> and <b>4</b> display dominant ferromagnetic interactions with a ground state of <i>S</i> = 12 for both clusters. Finally, <b>3</b> and <b>4</b> display single-molecule magnet behavior with <i>U</i><sub>eff</sub> = 63 and 36 K, respectively.</p>