K3[Fe3.26V0.74(OH)O(PO4)4(H2O)2]·2H2O: a synthetic leucophosphite

A new iron(III)/vanadium(III) phosphate, K₃[Fe_3.26V_0.74(OH)O(PO₄)₄(H₂O)₂]·2H₂O (1), has been obtained by hydrothermal synthesis and characterized by single crystal X-ray diffraction, Scanning electron microscopy–energy dispersive X-ray spectroscopy, Inductively coupled plasma atomic emission spectroscopy (ICP), thermogravimetric analysis, and FTIR spectroscopy. Single crystal X-ray diffraction reveals a 3D open framework (monoclinic, space group P2₁/n, a?=?9.6391(7)?Å, b?=?9.8063(7)?Å, c?=?9.7268(7)?Å, β?=?100.71(1)°, and V?=?903.38(11)?ų). This structure presents Fe^III and V^III in a 4.4?:?1?M ratio with the metal ions in two different crystallographic sites. Both metallic centers have distorted octahedral environments, linked by PO₄ tetrahedra, forming channels along the a-axis. The asymmetric unit of K₃[Fe_3.26V_0.74(OH)O(PO₄)₄(H₂O)₂]·2H₂O presents a {M₄(OH)O(PO₄)₄(H₂O)₂}^3? anionic entity, charge balanced by three K⁺, which are located within the channels. It is also possible to distinguish M₄O₂ units whose M^III polyhedra are linked by vertex and edges.     

Big macrocyclic assemblies of carboranes (big MACs): synthesis and crystal structure of a macrocyclic assembly of four carboranes containing alternate ortho- and meta-carborane icosahedra linked by para-phenylene units

The macrocyclic compound, [1,2-C₂B₁₀H₁₀-1,4-C₆H₄-1,7-C₂B₁₀H₁₀-1,4-C₆H₄]₂ (5)—a novel cyclooctaphane, was prepared by condensation of the C,C′-dicopper(I) derivative of meta-carborane with 1,2-bis(4-iodophenyl)-ortho-carborane. The X-ray crystal structure of 5·C₆H₆·6C₆H₁₂ was determined at 150 K, revealing an extremely loose packing mode. Molecule 5 has a crystallographic C_s and local C_2v symmetry; the macrocycle adopts a butterfly (dihedral angle 143°) conformation with the ortho-carborane units at the wingtips and the phenylene ring planes roughly perpendicular to the wing planes. Multinuclear NMR spectra suggest that molecule 5 in solution inverts rapidly via the planar D_2h geometry, which (from ab initio HF/6-31G* calculations) is only 1 kcal mol⁻¹ higher in energy than the C_2v one. An attempt to prepare an even larger macrocycle, comprising three para-carborane and three ortho-carborane units linked by six para-phenylene units, was unsuccessful.