Binuclear Coordination Assemblies of Metal Tetraphenylporphyrins (M = Mn, Fe, and In) with Anionic Thioindigo Bridges as Promising Magnetic Systems with Tunable Properties

A series of hybrids comprising two metal (Mn, Fe, and In) tetraphenylporphyrins axially substituted with anionic bidentate <i>trans</i>-thioindigo ligands (TI) were obtained. Substitution of the axial chloride anion by an oxygen atom of the dye forms short M-O bonds. Crystalline binuclear assemblies (TI^•-)·{[Mn^IITPP]⁰·[Mn^IIITPP]^<b>+</b>}·<i>x</i>C₆H₄Cl₂ (<i>x</i> = 2 for <b>1</b> or 1 for <b>2</b>) and (TI^2-){[M^IIITPP]⁺}₂·<i>x</i>C₆H₄Cl₂ (M = Fe and <i>x</i> = 2 for <b>3</b>, M = In and <i>x</i> = 1 for <b>4</b>) were synthesized. The thioindigo (TI^2-) dianion and metal (Fe^III and In^III) atoms in TPPs maintain their initial charge states during the formation of <b>3</b> and <b>4</b>, allowing the separation of paramagnetic Fe^III or diamagnetic In^III ions by a diamagnetic TI^2- bridge. Strong antiferromagnetic coupling is observed between Fe^III (<i>S</i> = 5/2) centers in complex <b>3</b>. Partial reduction of Mn^III to Mn^II occurs upon the formation of <b>1</b> and <b>2</b>, leading to assemblies containing three paramagnetic centers: Mn^II (<i>S</i> = 5/2), Mn^III (<i>S</i> = 2), and TI^•- radical anion (<i>S</i> = 1/2). Orthogonal arrangement of TPP and TI molecules in <b>1</b> provides strong ferromagnetic coupling. Weak antiferromagnetic coupling is realized in <b>2</b> due to the rotation of the TI bridge.