Study of the transformation of alpha- and beta-octamolybdate; crystal structure of bis(triethylammonium)bis(tetrabutylammonium)beta-octamolybdate dihydrate

Abstract

α-(NBu 4) 4[Mo 8O 26] reacts with NEt 3 in the presence of salicylaldehyde in methanol to afford the title complex. The complex has been characterized by elemental analysis and IR spectroscopy. The X-ray single crystal structure of the complex is described. The structural studies reveal that the molecular structure consists of a β-Mo 8O 26 polyanion with eight MoO 6 distorted edge-shared octahedra with short terminal MoO bonds (1.666-1.715 Å), bonds of intermediate length (1.858–1.999 Å) and long bonds (2.133–2.485 Å). Two different types of hydrogen bonds have been found: NH ··· O (2.85–3.12 Å) and CH ··· O (3.18–3.54 Å). In the transformation of α- and β-Mo 8O 26 the smaller the cation, the easier the formation of β-octamolybdate.