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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 trans-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•–)·{[MnIITPP]0·[MnIIITPP]+}·xC6H4Cl2 (x = 2 for 1 or 1 for 2) and (TI2–){[MIIITPP]+}2·xC6H4Cl2 (M = Fe and x = 2 for 3, M = In and x = 1 for 4) were synthesized. The thioindigo (TI2–) dianion and metal (FeIII and InIII) atoms in TPPs maintain their initial charge states during the formation of 3 and 4, allowing the separation of paramagnetic FeIII or diamagnetic InIII ions by a diamagnetic TI2– bridge. Strong antiferromagnetic coupling is observed between FeIII (S = 5/2) centers in complex 3. Partial reduction of MnIII to MnII occurs upon the formation of 1 and 2, leading to assemblies containing three paramagnetic centers: MnII (S = 5/2), MnIII (S = 2), and TI•– radical anion (S = 1/2). Orthogonal arrangement of TPP and TI molecules in 1 provides strong ferromagnetic coupling. Weak antiferromagnetic coupling is realized in 2 due to the rotation of the TI bridge.