Microwave-assisted synthesis and crystal structure of oxo(diperoxo)(4,4'-di-tert-butyl-2,2'-bipyridine)-molybdenum(VI)

Abstract

The oxodiperoxo complex MoO(O2)(2)(tbbpy) (tbbpy = 4,4'-di-tert-butyl-2,2'- bipyridine) was isolated from the reaction of MoO2Cl(2)(tbbpy) in water under microwaveassisted heating at 120 masculineC for 4 h. The structure of the oxodiperoxo complex was determined by single crystal X-ray diffraction. The Mo(VI) centre is seven-coordinated with a geometry which strongly resembles a highly distorted bipyramid. Individual MoO(O2)(2)(tbbpy) complexes are interdigitated along the [010] direction to form a column. The crystal structure is formed by the close packing of the columnar-stacked complexes. Interactions between neighbouring columns are essentially of van der Waals type mediated by the need to effectively fill the available space.

Figure 1

Schematic representation of the neutral MoO(O₂)₂(tbbpy) molecular unit present in the crystal structure of 1, showing the labelling scheme for all non-hydrogen atoms. Thermal ellipsoids are drawn at the 50% probability level and hydrogen atoms are represented as small spheres with arbitrary radii. The disorder associated with the coordinated peroxo (O2'-O3') and oxo (= O1') groups [21.9(7)% occupancy] has been omitted for clarity. Table 1 collects selected bond lengths and angles for the distorted bipyramidal {MoN₂O₅} coordination environment. Symmetry transformation used to generate equivalent atoms: (i) x, 1.5-y, z.

Figure 2

Structure overlay of the two disordered positions for the MoO(O₂)₂(tbbpy) complex present in 1, emphasising the small geometrical differences for the first coordination sphere of Mo^VI.

Figure 3

Schematic representation of the interdigitation of individual MoO(O₂)₂(tbbpy) complexes along the [010] direction of the unit cell. For simplicity only the most probable locations of the coordinated peroxo and oxo groups are represented.

Figure 4

Crystal packing of MoO(O₂)₂(tbbpy) (1) viewed in perspective along the [010] direction of the unit cell. For simplicity only the most probable locations of the coordinated peroxo and oxo groups are represented.