Access to a novel niobium octahedral cluster core via soft chemistry: synthesis and structure of K2.6Cs3.4[Nb6Cl4O4(OH)4(CN)6]·3H2O containing isolated Nb6Cli4Oi4(OH)i4(CN)a6 cluster unit

The synthesis and the structure of K2.6Cs3.4[Nb6Cl4O4(OH)4(CN)6]·3H2O are described in the present work. It has been obtained by the interaction of Cs2Ti3Nb12Cl27O8 oxychloride with an aqueous solution of potassium cyanide. The crystal structure—determined by single crystal X-ray diffraction at room temperature (monoclinic, C2/c, a=13.4336(3) Å, b=15.9281(3) Å, c=15.9619(3) Å, β=90.2177(9)°, V=3415.3(1) Å3, Z=4)—is built from a novel (Nb6Oi4(OH)i4Cli4) cluster core which exhibits for the first time four hydroxyl groups in addition to four chlorine and four oxygen atoms in inner position; six apical CN ligands complete the coordination of the Nb6 cluster. Structural and electronic properties of this unit are discussed by comparison with other niobium oxychlorides and oxides based on (Nb6Cl12−xOx)n+ cluster core.