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RESEARCH PRODUCT

A novel octacyanido dicobalt(iii) building block for the construction of heterometallic compounds

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description

The first bimetallic octacyanido complex of CoIII, (PPh4)2[Co2(μ-2,5-dpp)(CN)8] (1), was synthesized and used as a metalloligand with [Mn(MAC)(H2O)2]Cl2·4H2O to give a new {CoIIIMnII} heterometallic chain of formula [MnII(MAC)(μ-NC)2Co2III(μ-2,5-dpp)(CN)6]n·7nH2O (2) (PPh4+ = tetraphenylphosphonium cation; 2,5-dpp = 2,5-bis(2-pyridyl)pyrazine and MAC = 2,13-dimethyl-3,6,9,12,18-pentaazabicyclo-[12.3.1]octadeca-1(18),2,12,14,16-pentaene). Both compounds were characterized by single-crystal X-ray diffraction. Compound 1 contains a diamagnetic 2,5-dpp-bridged dicobalt(III) unit with four peripheral cyanide ligands at each cobalt center achieving a six-coordinate surrounding, the electroneutrality being ensured by bulky tetraphenylphosphonium cations. The structure of 2 consists of neutral heterobimetallic chains where the [Co2(μ-2,5-dpp)(CN)8]2− complex anion adopts a bis-monodentate bridging mode towards the [Mn(MAC)]2+ cation. Each manganese(II) ion in 2 is seven-coordinate with five quasi coplanar nitrogen atoms from the macrocycle and two trans-positioned cyanide-nitrogen atoms building a somewhat distorted pentagonal bipyramidal environment. Cryomagnetic measurements for 2 reveal the occurrence of quasi magnetically isolated spin sextets in the temperature range of 1.9–300 K.