Crystal Structure of Vanadyl Bisacetylacetonate. Geometry of Vanadium in Fivefold Coordination

Abstract

The structure of vanadyl bisacetylacetonate has been determined from three-dimensional x-ray diffraction data. The crystals are triclinic, space group P1̄, with a=7.53±0.02 A, b=8.23±0.03 A, c=11.24±0.04 A, α=73.0°, β=71.3°, γ=66.6°, Z=2. The structure consists of discrete molecules of VO(C5H7O2)2. Each vanadium atom has five oxygen neighbors at the corners of a rectangular (nearly square) pyramid, with vanadium near its center of gravity. The vanadium-oxygen distances are 1.56 A to the apex atom (vanadyl oxygen) and 1.96, 1.96, 1.97, and 1.98 A to the others. Other bond distances average 1.28 A for C–O, 1.40 A for C–C (ring), and 1.52 A for C–C (methyl). Standard deviations are 0.01 A for V–O bonds and 0.02 A for C–O and C–C bonds. Each acetylacetone skeleton is planar, and this plane makes an angle of 163° with the plane of the other acetylacetone skeleton of the same molecule.

Structure of aquaoxo(N-salicylidene-L-alaninato)vanadium(IV)

“…The Schiff-base ligand has the usual dimensions. The vanadyl V=O bond length is 1.578 (3)/k, which agrees well with bond lengths found in related systems (Dodge, Templeton & Zalkin, 1961;Hon, Belford & Pfluger, 1965). The V atom deviates 0.614 (2)/k from the basal plane towards the vanadyl O atom; this is slightly more than is usual in corresponding complexes with coordination number five (0.48-0.58/k), but, for example, still in the range 0.48-0.72/k predicted by extended Hfickel molecular-orbital calculations for porphin systems (Zerner & Gouterman, 1966).…”

Adducts of oxovanadium(IV) dithiocarbamates

“…It is quite reasonable to expect that the 0-V-S angles in the bis-dithiocarbamates are greater than 9O0, since it has been shown that in other 5-coordinate dithiocarbamate complexes the metal atom is above the basal plane of the equatorial ligands (6)(7)(8). It should also be pointed out that O=V-0 angles in VO(acetylacetonate), are 106" (9). In view of these observations it is not difficult to understand the applicability of the inverted level scheme to the bis-dithiocarbamates, although it is difficult to assess the relative roles of n-bonding and 0-V-S angle distortions from 90".…”

Oxobis(2,4-pentanedionato)vanadium(IV), a Redetermination

“…2.9(I) 0.0269 (5) 0.9347 (5) 0.1785 (1) 2. diketonate) species (McNeill, Yuen, Hoveyda & Orvig, 1992, and references therein), an accurate structure of one of the simplest members of this class of compounds would facilitate the assessment of structural subtleties which may be an important factor in determining the potency of the insulin-mimicking effect. The original report of the structure (Dodge, Templeton & Zalkin, 1961) is based on a visual Cu data set. A later paper reports an anisotropic refinement using the same set of data (Hon, Belford & Pfluger, 1965).…”

“…The unit-cell can be transformed to that used by Dodge, Templeton & Zalkin (1961) by using the matrix: (0 0 1, -1 0 0, 0 -1 0). The scan width was (1.21 + 0.35tan0) ° with a 0 scan rate of 32 ° min -1 (up to nine scans).…”