Di-μ-chlorido-bis[diacetonitrilechloridooxidovanadium(IV)]

The title compound, [V2Cl4O2(CH3CN)4], is a centrosymmetric dinuclear VIV complex associated with four molecules of acetonitrile. The coordination around both VIV atoms is essentially square-planar, involving three Cl atoms and one O atom [maximum deviation = 0.017 (3) Å for the O atom]. The augmented octahedral coordination of the metal atom is completed by the N atoms of acetonitrile ligands. The VIV atoms are linked by two Cl atoms, acting as bridging atoms. The crystal studied was a non-merohedral twin with a ratio of the two twin components of 0.8200 (3):0.1800 (3). Although Cl and O atoms are present as potential acceptors in the title compound, no hydrogen bonds were observed in the crystal structure.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RU2013).
The dichloro(oxo)vanadium(IV) complex with acetonitrile was prepared for the first time by the reaction of VOCl 2 with dry acetonitrile (du Preez et al. , 1967). The structure characteristic of the reaction product was performed only by means of UV, IR and conductivity measurements. The constitution of this reaction product was determined as VOCl 2 .2.5CH 3 CN.

Experimental
The title compound was obtained by the reaction of VOCl 3 with N,N'-bis(trimethylsilyl)urea in acetonitrile. N,N'bis(trimethylsilyl)urea (3.0 mmol) was dissolved in 100 cm 3 of dry acetonitrile at 70 °C. The solutoin of VOCl 3 (2.6 mmol) in in dry acetonitrile (50 cm 3 ) was quickly added to the solution of N, N'-bis(trimethylsilyl)urea and the reaction mixture was refluxed for 17 h. The solvent was partially distilled off after the reaction and the total volume was reduced to 25 cm 3 .
Dry CCl 4 (25 cm 3 ) was consequently added to the concentrated acetonitrile solution and two liquid phases were formed.

Refinement
The investigated crystal was a non-merohedral twin [twin law: rotation of 180° around the [101] direction].. The twin law was determined using TwinRotMat implemented in PLATON (Spek, 2009). The twinning coefficient of the crystal is 0.180040. The description of twin law in transformation matrix is: (0.397 -0.364 0.603) (0.000 -1.000 0.000) (1.397 -0.364 -0.397) The detwinned data were obtained by HKLF 5 option in the SHELXL97 program (Sheldrick, 2008) and the final refinement was carried out against the detwinned data set.