In Situ Ligand Transformation in the Synthesis of Manganese Complexes: Mono-, Tri- and a Barrel-shaped Tetradeca-nuclear Mn<sup>II</sup><sub>14</sub> Aggregate AnwarMuhammad Usman LanYanhua M. C. BeltranLianne CléracRodolphe PfirrmannSven AnsonChristopher E. PowellAnnie K. 2009 Three one-pot syntheses leading to four examples of in situ ligand transformations are presented. These in situ reactions involve various transformations of 2-(<i>N'</i>-dicyanomethylene-hydrazino)-benzoic acid (DHB). The resulting ligands enabled the preparation of three new coordination compounds, which were fully characterized by infrared spectroscopy, elemental analysis, and single crystal X-ray diffraction. The complex, [Mn<sup>III</sup>(Lig-I)(CH<sub>3</sub>OH)Cl] (<b>1</b>), was prepared in a one-pot synthesis in which the aryl hydrazone ligand, (Lig-I)<sup>2−</sup>, was formed by the amination of DHB resulting from the nucleophilic attack of an amino group of ethylenediamine. The linear, mixed-valence trinuclear complex, (Et<sub>3</sub>NH)<sub>4</sub>[Mn<sup>III</sup><sub>2</sub>Mn<sup>II</sup>(μ-OH)<sub>2</sub>(Lig-II)<sub>2</sub>(HLig-II)<sub>2</sub>] (<b>2</b>), was synthesized using a preparation involving the in situ reaction of azide and a nitrile of DHB. Larger species can also be prepared using this technique. In a reaction involving two different in situ ligand formations, the cyclocondensation of two DHB molecules and the partial hydrolysis of a nitrile of DHB, the first example of a tetradecanuclear Mn(II) aggregate, (H<sub>3</sub>O)<sub>4</sub>[Mn<sup>II</sup><sub>14</sub>(μ<sub>6</sub>-CO<sub>3</sub>)(μ<sub>3</sub>-OH)<sub>6</sub>(HLig-III)<sub>6</sub>(HLig-IV)<sub>3</sub>(OH<sub>2</sub>)<sub>3</sub>]·92MeCN (<b>3</b>), was isolated and characterized. Magnetic measurements on <b>2</b> indicate the presence of intramolecular and intermolecular antiferromagnetic interactions (<i>J</i><sub>1</sub>/<i>k</i><sub>B</sub> = −9.5(1) K, <i>g</i> = 1.95(2), and z<i>J′</i>/<i>k</i><sub>B</sub> = −0.37(5) K) while those on <b>3</b> suggest the presence of dominating antiferromagnetic interactions.