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

Abstract

New dinuclear carboranylcarboxylate-bridged and mononuclear copper(ii) compounds containing the 1-CO2H-2-H-1,2-closo-C2B10H10 carborane ligand () have been synthesized from the previously synthesized dinuclear compound [Cu2(μ-L)4(THF)2], . Reaction of with CuSO4 in THF leads to the dinuclear compound [Cu2(μ-L)4(THF)2], . The reaction of with different terminal pyridyl ligands leads to the formation of a series of structurally analogous complexes by substitution of the terminal ligand THF (Lt = py, ; p-CF3-py, ; p-CH3-py, ), which maintain the structural Cu2(μ-O2CR)4 core in most of the cases except for o-(CH3)2-py where a mononuclear compound () is exclusively obtained. In the case of and , other dinuclear compounds [Cu2(L)4(Lt)4], and are obtained in lower yield. These compounds have been characterized using analytical, spectroscopic (NMR, IR, UV-visible) and electrochemical techniques (CV, DPV). X-ray analysis revealed a paddle-wheel structure for the main dinuclear compounds with a square-pyramidal geometry around each copper ion and the carboranylcarboxylate ions bridging two copper atoms in syn-syn mode. In the case of and there are two carboranylcarboxylate ions bridging the copper atoms in syn-anti mode whereas the other two adopt a monodentate coordination mode. The mononuclear complex obtained with the o-(CH3)-py ligand presents a square-planar structure, in which the carboranylcarboxylate ligand adoptsmonodentate coordination. The effect of the substituent group on the cluster of the carboranylcarboxylate ligands on the reactivity of compound is also discussed.

Effect of the Pyridine Substituent on the Role of the Phenol Functional Group in [Cu(pOHBz)2(dPy)2] Complexes (pOHBz: p‐Hydroxybenzoate, dPy= 4‐Phenylpyridine, 4‐Benzylpyridine, 3‐Phenylpyridine).

“…The non‐bridging carboxylate adopts a bonding mode from a clearly asymmetric chelating to monodentate. The Cu(2)‐N bond lengths are also in good agreement with the values reported for similar compounds …”

Effect of Nature of Substituents on Coordination Properties of Mono- and Disubstituted Derivatives of Boron Cluster Anions [BnHn]2– (n = 10, 12) and Carboranes with exo-Polyhedral B–X Bonds (X = N, O, S, Hal)

“…In complexation reactions, there are a great number of complexes with derivatives containing C-X exo-polyhedral bonds. Thus, carboranylphosphine ligands (with C-P exo-polyhedral bonds) are generalized in a recent review [62]; chalcogenocarboranes with C-X bonds (X = S, Se, Te) were summarized [112][113][114]; carboxy [115][116][117][118][119][120][121], carbene [122], and acetylene [123] derivatives with the C-C exo-polyhedral bonds were discussed in the corresponding reviews. The carboranyl-based N,O-donor compounds functionalized by the carbon atom of the carborane cage have been thoroughly studied [123][124][125][126][127][128][129].…”

m-Carboranylphosphinate as Versatile Building Blocks To Design all Inorganic Coordination Polymers

“…The use of carboranes in supramolecular chemistry is a topic that generates great interest for their particular properties, which may induce unconventional characteristics in the supramolecular structures in which they are inserted . The geometrical features found in the complexes of [1-CO 2 -1,2- closo -C 2 B 10 H 11 ] − with manganese­(II), copper­(II), and cobalt­(II) could not be compared with those of derivatives of conventional monocarboxylate ligands. The carboranyl group with its spherical shape is difficult to compare with organic fragments if we do not consider C 60 or dodecahedrane C 20 H 20 ; besides, it displays good hydrophobicity and electron-withdrawing properties through the carbon-atom vertices.…”