Synthesis of quadruped-shaped polyfunctionalized o-carborane synthons

[EN] o-Carborane derivatives with precisely defined patterns of substitution have been prepared from 8,9,10,12-I-4-1,2-closo-C2B10H8 by replacing the iodine atoms, bonded to four adjacent boron vertices in the cluster, with allyl, and subsequently 3-hydroxypropyl groups. The resulting structures, comprising four pendant arms and two reactive vertices located on opposite sides of a central o-carborane core, can be envisaged as versatile precursors for dendritic growthThis work was supported by Generalitat de Catalunya 209/SGR/00279 and Spanish Ministerio de Ciencia e Innovacion by CTQ2010-16237.Puga, AV.; Teixidor, F.; Sillanpaa, R.; Kivekas, R.; Viñas, C. (2011). Synthesis of quadruped-shaped polyfunctionalized o-carborane synthons. Chemical Communications. 47(8):2252-2254. https://doi.org/10.1039/c0cc05151aS2252225447

Iodinated ortho-Carboranes as Versatile Building Blocks to Design Intermolecular Interactions in Crystal Lattices

[EN] The crystal structures of numerous iodinated ortho-carboranes have been studied, which has revealed the diversity of intermolecular interactions that these substances can adopt in the solid state. The nature-mostly as it relates to hydrogen and/or halogen bonds-and relative strength of such interactions can be adjusted by selectively introducing substituents onto the cluster, thus enabling the rational design of crystal lattices. In this work we present the newly determined crystal structures of the following iodinated ortho-carboranes: 9-I-1,2-closo-C2B10H11, 4,5,7,8,9,10,11,12-I-8-1,2-closo-C2B10H4, 3,4,5,6,7,8,9,10,11,12-I-10,-1,2-closo-C2B10H2, 1-Me-8,9,10,12-I-4-1,2-closo-C2B10H7, 1,2-Me-2-8,9,10,12-I-4-1,2-closo-C2B10H6, and 1,2-Ph-2-8,9,10,12-I-4-1,2-c1oso-C2B10H6. Their 3D supramolecular organization has been thoroughly investigated and compared to similar previously published crystal structures. Such a systematic survey has allowed us to draw some general trends. C-c-H center dot center dot center dot I-B hydrogen bonds (C-c = cluster carbon atoms) appear to be significant in the growth of the crystal lattices of these compounds, given the acidity of hydrogen atoms bonded to C-c, and the polarization of B-I bonds. These hydrogen bonds can be disrupted by selectively blocking the positions next to C-c that is, B(3) and B(6), with bulky substituents that prevent iodine atoms from approaching as hydrogen acceptors. Halogen bonds of the type B-I center dot center dot center dot I-B are frequently observed in most cases, thus suggesting that these interactions could be attractive in boron clusters. In addition, different substituents can be grafted onto the ortho-carborane surface, thereby providing further possibilities for homomeric or heteromeric molecular assembly.This work was supported by CICYT (project MAT2006-05339), Generalitat de Catalunya (2005/SGR/00709).Puga, AV.; Teixidor, F.; Sillanpaa, R.; Kivekas, R.; Viñas, C. (2009). Iodinated ortho-Carboranes as Versatile Building Blocks to Design Intermolecular Interactions in Crystal Lattices. Chemistry - A European Journal. 15(38):9764-9772. https://doi.org/10.1002/chem.200900926S97649772153

Conformationally locked pentadentate macrocycles containing the 1-10-phenantroline unit. Synthesis and crystal structure of 5-oxa-2,8-dithia[9](2,9-1,10-phenantrolinophane (L) and its coordination properties to NiII, PdII, PtII, RhIII and RuII.

The complexation of the new mixed thia-aza-oxa macrocycle 5-oxa-2,8-dithia[9](2,9)-1,10-phenanthrolinophane (L) containing the 1,10-phenanthroline unit with Ni-II, Pd-II, Pt-II, Rh-III and Ru-II has been investigated. The results have been compared with those obtained with the structurally related ligand 2,5,8-trithia[9](2,9)-1,10-phenanthrolinophane (L'). The most stable conformations of both ligands have been calculated in order to understand their change upon metal complexation and for L good agreement has been found with the conformations observed in the crystal structure of L .1/2H(2)O. The single-crystal structures of [Ni(L)Cl]BF4 and [Ru(L)(PPh3)][PF6](2).1/4MeCN reveal a N2S2O coordination sphere about Ni-II and Ru-II, with the macrocyclic ligand in a folded conformation and with the sixth coordination site taken up by Cl- or PPh3, respectively. For [Pd(L)][BF4](2) an [N2S2 + O] coordination is observed, with the O-donor interacting weakly with the metal centre at the apical position of a square-based coordination sphere. C-13 and H-1 NMR spectroscopic studies indicate that the complexes are not fluxional in solution, with the ligand imposing the same coordination sphere as observed in the solid state. C-13 NMR spectroscopy has also helped in elucidating the stereochemistry of [Rh(L)Cl-2]BF4 for which no suitable crystals could be grown: the two Cl- ligands are mutually trans with the N2S2 donor set of the macrocyclic ligand occupying the equatorial positions of an octahedral coordination sphere and with the O-donor atom left un-coordinated. The redox properties of all the complexes in MeCN have been studied

Mixed aza-thia crowns containing the 1,10-phenanthroline sub-unit. Substitution reactions in [NiL(MeCN)][BF4]2 L = 2,5,8-trithia[9](2,9)-1,10-phenanthrolinophane

The substitution reactions of the co-ordinated acetonitrile molecule in [NiL(MeCN)][BF4]2 1 (L = 2,5,8-trithia- [9](2,9)-1,10-phenanthrolinophane) with different anionic and neutral ligands L9 [Cl2, Br2, I2, CN2, SCN2, H2O, pyridine (py), aniline (an), 1,3-dimethyl-4-imidazoline-2-thione (etu) or 1,3-dimethyl-4-imidazoline-2-selone (eseu)] have been studied by using electronic spectroscopy. While the reaction with all the anionic ligands is quantitative, for the neutral ones an equilibrium takes place; the corresponding equilibrium constants have been determined in MeCN at 25 8C. The complex cations [NiL(L9)](2 2 n)1 (n = 0 for neutral and 1 for anionic ligands) have also been isolated in the solid state, mainly as BF4 2 salts and the compounds [NiL(H2O)][ClO4]2?H2O, [NiL(Cl)]Cl?H2O, [NiL(SCN)]- BF4?MeNO2, [NiL(eseu)][BF4]2 and [NiL(py)][BF4]2 have been characterized by X-ray diffraction studies. In these complexes a distorted octahedral geometry is achieved at the NiII with five sites occupied by the macrocyclic ligand L and the sixth by the appropriate ligand L9. The electrochemistry of all the prepared compounds has been studied by cyclic voltammetry. In particular the reductive cyclic voltammetry of 1 in acetonitrile shows a quasi-reversible one-electron reduction wave near 1E2¯ 1 = 21.0 V vs. Fc/Fc1. Electrochemical reduction by controlled-potential electrolysis at this potential in the presence of the axial ligand PMe3 and investigation of the reduced product by ESR spectroscopy confirm the reduction process to be metal based and to correspond to the formation of the [NiIL]1 species