(Acetylacetonato-κ2 O,O′)chloridotrimethanolatoniobium(V)

In the title compound, [Nb(CH3O)3(C5H7O2)Cl], the NbV atom is coordinated by two O atoms from the chelating acetylacetonate ligand, three O atoms from the methanolate groups and one chloride ligand. The octahedral environment around niobium is slightly distorted with Nb—O distances in the range 1.8603 (15)–2.1083 (15) Å and an Nb—Cl distance of 2.4693 (9) Å. The O—Nb—O angles vary between 80.74 (6) and 100.82 (7)°, while the trans Cl—Nb—O angle is 167.60 (5)°. There are no hydrogen bonds observed, only an intermolecular C—H⋯O interaction.

In the title compound, [Nb(CH 3 O) 3 (C 5 H 7 O 2 )Cl], the Nb V atom is coordinated by two O atoms from the chelating acetylacetonate ligand, three O atoms from the methanolate groups and one chloride ligand. The octahedral environment around niobium is slightly distorted with Nb-O distances in the range 1.8603 (15)-2.1083 (15) Å and an Nb-Cl distance of 2.4693 (9) Å . The O-Nb-O angles vary between 80.74 (6) and 100.82 (7) , while the trans Cl-Nb-O angle is 167.60 (5) . There are no hydrogen bonds observed, only an intermolecular C-HÁ Á ÁO interaction.
Financial assistance from the Advanced Metals Initiative (AMI) and the Department of Science and Technology (DST) of South Africa, the New Metals Development Network (NMDN), the South African Nuclear Energy Corporation Limited (Necsa) and the University of the Free State is gratefully acknowledged.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PV2289).
Pale-yellow cubic crystals of the title complex crystallize from a methanol reaction solution containing niobium(V) chloride and acetylacetone after several days (Davies et al., 1999). The asymmetric unit consists of a niobium(V) atom surrounded by three methanolate groups, a chloride ligand and a O,O'-bonded acetylacetonato ligand ( Figure 1). The octahedral environment around niobium is slightly distorted with Nb-O distances varying between 1.8603 (15) and 2.1083 (15) Å, while the Nb-Cl distance is 2.4693 (9) Å. The O-Nb-O angles vary between 80.74 (6) and 100.82 (7) ° while the trans Cl-Nb-O angle is 167.60 (5) °. All the bond distances and angles are similar to other relevant niobium(V) structures (Sokolov et al., 1999;2005;Antinolo et al., 2000 andDahan et al., 1976). The niobium compounds pack in a head-to-tail fashion along the bc plain.

Experimental
The reaction was performed under modified Schlenk conditions under an argon atmosphere. NbCl 5 (0.3134 g, 1.16 mmol) was carefully dissolved in absolute methanol (5 ml) (Care: exothermic reaction). Acetylacetone (0.119 ml, 1.16 mmol) was added to the solution. The colourless solution was stirred for 1 h at room temperature and the solution was left to stand at 252 K for a few days after which pale-yellow crystals, suitable for X-ray diffraction were obtained.

Refinement
The methyl and aromatic H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C-H = 0.95 and 0.98Å and U iso (H) = 1.5U eq (C) and 1.2U eq (C), respectively. The highest residual electrondensity peak is 0.93 Å from Cl1.

Special details
Experimental. The intensity data were collected on a Bruker X8 ApexII 4 K Kappa CCD diffractometer using an exposure time of 60 s/frame. A total of 688 frames were collected with a frame width of 0.5° covering up to θ = 28.24° with 99.1% completeness accomplished.
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.