Water-Soluble Manganese Inorganic Polymers: The Role of Carborane Clusters and Producing Large Structural Adjustments from Minor Molecular Changes

Abstract

The reaction of two different carboranylcarboxylate ligands, 1-CH3-2-CO2H-1,2-closo-C2B10H10 or 1-CO2H-1,2-closo-C2B10H11, with MnCO3 in water leads to polymeric compounds 1a and 1b. Both compounds have been characterized by analytical and spectroscopic techniques. Additionally, electrochemical techniques have also been used for compound 1a. X-ray analysis revealed substantial differences between both compounds: whereas a six-coordinated Mn-II compound with water molecules bridging two Mn-II centers has been observed for 1a, a square pyramidal geometry around each Mn-II ion with terminal water molecules coordinated to each Mn-II center has been found for 1b. The observed differences have been attributed to the existence of different substituents, -CH3 or -H, on one of the carbon atoms of the carboranylcarboxylate ligand. The reaction of 1a and 1b with coordinating solvents, such as ethers or Lewis bases, leads to the formation of new compounds with low (mononuclear 4a, 4b; dinuclear 3a, 3b; and trinuclear 2a) or high nuclearity (hybrid polymer, 5a), due to breakage of the corresponding polymer. X-ray analysis shows that the structural core present in the polymeric materials is not maintained in the resulting compounds, with the exception of trinuclear compound 2a. The magnetic properties of the compounds studied show weak antiferromagnetic coupling