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 1 a and 1 b. Both compounds have been characterized by analytical and spectroscopic techniques. Additionally, electrochemical techniques have also been used for compound 1 a. 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 1 a, a square pyramidal geometry around each Mn(II) ion with terminal water molecules coordinated to each Mn(II) center has been found for 1 b. 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 1 a and 1 b with coordinating solvents, such as ethers or Lewis bases, leads to the formation of new compounds with low (mononuclear 4 a, 4 b; dinuclear 3 a, 3 b; and trinuclear 2 a) or high nuclearity (hybrid polymer, 5 a), 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 2 a. The magnetic properties of the compounds studied show weak antiferromagnetic coupling.

Intramolecular hydrogen bonding stabilizes the nuclearity of complexes. A comparative study based on the H-carborane and Me-carborane framework

“…21 The difference between the frequencies of the symmetric and antisymmetric stretches of carboxylates groups lies between the ranges quoted for bidentate bridged ligands. 22 The 1 H{ 11 B}-, 11 B-and 11 B{ 1 H}-spectra of these compounds are in agreement with the solid structures confirmed by X-ray crystallography. It can be observed that the 11 B{ 1 H}-NMR resonances of all complexes featured similar patterns in the range δ = 2 to −15 ppm that is consistent with a closo cluster.…”

“…22 The 1 H{ 11 B}-, 11 B-and 11 B{ 1 H}-spectra of these compounds are in agreement with the solid structures confirmed by X-ray crystallography. It can be observed that the 11 B{ 1 H}-NMR resonances of all complexes featured similar patterns in the range δ = 2 to −15 ppm that is consistent with a closo cluster. 23 The 1 H{ 11 B}-spectra exhibit the resonances of the protons bonded to the B atoms as broad singlets in the chemical-shift range of δ = 0 to +5 ppm and resonances attributed to the C c -H protons appear in the range δ = 3.42 to 4.40 ppm.…”

“…It can be observed that the 11 B{ 1 H}-NMR resonances of all complexes featured similar patterns in the range δ = 2 to −15 ppm that is consistent with a closo cluster. 23 The 1 H{ 11 B}-spectra exhibit the resonances of the protons bonded to the B atoms as broad singlets in the chemical-shift range of δ = 0 to +5 ppm and resonances attributed to the C c -H protons appear in the range δ = 3.42 to 4.40 ppm. The aromatic pyridine protons were not observed in 1 H{ 11 B}-NMR spectra at 298 K for any complex.…”

“…9 Recently we have reported the coordination of the carboranylcarboxylate ligands [1-CO 2 -2-CH 3 -1,2-closo-C 2 B 10 H 10 ] − and [1-CO 2 -2-H-1,2-closo-C 2 B 10 H 10 ] − with Mn II ions to generate polymeric structures. 10,11 In these cases, too, the observed differences have been attributed to the existence of different substituents, -CH 3 or -H, on one of the carbon atoms of the carboranylcarboxylate ligand. We have also reported the synthesis and characterization of copper complexes containing the carboranylcarboxylate ligand, L′ = [1-CO 2 -2-CH 3 -1,2-closo-C 2 B 10 H 10 ] − , along with their coordination chemistry and physical and chemical properties.…”

A Reversible Phase Transition of 2D Coordination Layers by B–H∙∙∙Cu(II) Interactions in a Coordination Polymer

“…Such properties make icosahedral carborane clusters valuable ligands for CPs or MOFs. For example, some of us have reported the synthesis and electronic and magnetic properties of purely inorganic CPs based on the monocarboxylic acid of ortho -carborane [33,34,35]. Mirkin and co-workers explored the use of di-, tri- and tetra-carboxylic acid derivatives of para -carborane ( I to IV in Scheme 1) for CPs synthesis, providing a series of CPs exhibiting unprecedented stabilities with respect to thermal degradation, inherited from the carborane moiety [36,37,38,39,40,41,42].…”