Water-soluble manganese inorganic polymers: the role of carborane clusters and producing large structural adjustments from minor molecular changes.

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.

Design of dinuclear copper species with carboranylcarboxylate ligands: study of their steric and electronic effects.

A series of new mononuclear and carboranylcarboxylate-bridged dinuclear copper(II) compounds containing the 1-CH(3)-2-CO(2)H-1,2-closo-C(2)B(10)H(10) carborane ligand (LH) has been synthesized. Reaction of different copper salts with LH at room temperature leads to dinuclear compounds of the general formula [Cu(2)(µ-L)(4)(L(t))(2)] (L(t) = thf (1), L(t) = H(2)O (1')). The reaction of 1 and 1' with different terminal pyridyl (py) ligands leads to the formation of a series of structurally analogous complexes by substitution of the terminal ligand thf or H(2)O (L(t) = py (2), p-CF(3)-py (3), p-CH(3)-py (4), pz (6), and 4,4'-bpy (7)), which maintain the structural Cu(2)(µ-O(2)CR)(4) core in the majority of the cases except for o-(CH(3))(2)-py, where a mononuclear compound (5) is exclusively obtained. These compounds have been characterized through analytical, spectroscopic (NMR, IR, UV-visible, ESI-MS) and magnetic techniques. X-ray structural analysis revealed a paddle-wheel structure for the dinuclear compounds, with a square-pyramidal geometry around each copper ion and the carboranylcarboxylate ions bridging two copper atoms in syn-syn mode. The mononuclear complex obtained with the o-(CH(3))(2)-py ligand presents a square-planar structure, in which the carboranylcarboxylate ligand adopts a monodentate coordination mode. The magnetic properties of the dinuclear compounds 1, 3, 4, and 6 show a strong antiferromagnetic coupling in all cases (J = -261 (1), -255 (3), -241 (4), -249 cm(-1) (6)). Computational studies based on hybrid density functional methods have been used to study the magnetic properties of the complexes and also to evaluate their relative stability on the basis of the strength of the bond between each Cu(II) and the terminal ligand.

Carving a 1D Co(II)-carboranylcarboxylate system by using organic solvents to create stable trinuclear molecular analogues: complete structural and magnetic studies.

This work presents a straightforward methodology to achieve small linear trinuclear molecules based on the Co(II)-carboranylcarboxylate system obtained by carving a 1D polynuclear analogous system with the use of diethylether. The reaction of the carboranylcarboxylic ligand, 1-CH3-2-CO2H-1,2-closo-C2B10H10 (LH) with different cobalt salts leads to the polynuclear compound [Co2(µ-H2O)(1-CH3-2-CO2-1,2-closo-C2B10H10)4(THF)4], and the polymeric [Co(µ-H2O)(1-CH3-2-CO2-1,2-closo-C2B10H10)2]n(H2O)n. This latter 1D chain has been obtained by an unprecedented synthetic strategy for the isolation of cobalt(ii) compounds. [Co3(µ-H2O)2(1-CH3-2-CO2-1,2-closo-C2B10H10)6(H2O)2(C4H10O)2], is formed by the dissociation of the polymeric structure that forms when a mild coordinating solvent such as diethylether is added. These compounds have been characterized by analytical and spectroscopic techniques. X-ray analysis of and revealed that presents a dinuclear structure whereas is trinuclear; in both cases a six-coordinated Co(II) compound with water molecules bridging each of the two Co(II) centres has been observed. The magnetic properties of and show a weak antiferromagnetic behaviour, respectively, between the Co(II) centres mediated by two carboxylate ligands and a molecule of water.

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

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.

A water soluble Mn(II) polymer with aqua metal bridges.

The first water soluble and crystallographically determined polynuclear Mn(II) complex, with water molecules bridging every two Mn centers, is reported. This is an unusual feature in 1D oligomer Mn(II) compounds with a nuclearity higher than 2. The polymer structure is largely preserved in water.