Bis[1,2-bis(dimethylphosphino)ethane]dichloridonitrosyltungsten(0) chloride

In the crystal structure of the title compound, [WCl2(NO)(C6H16P2)2]Cl, the seven-coordinated tungsten(II) center displays a distorted pentagonal–bipyramidal geometry with trans nitrosyl and chloride ligands. The NO and Cl ligands are disordered over two positions; the site occupancy factors are 0.6 and 0.4.

In the crystal structure of the title compound, [WCl 2 (NO)-(C 6 H 16 P 2 ) 2 ]Cl, the seven-coordinated tungsten(II) center displays a distorted pentagonal-bipyramidal geometry with trans nitrosyl and chloride ligands. The NO and Cl ligands are disordered over two positions; the site occupancy factors are 0.6 and 0.4.
Bis[1,2-bis(dimethylphosphino)ethane]dichloridonitrosyltungsten(0) chloride Nataša Avramović, Olivier Blacque, Helmut W. Schmalle and Heinz Berke S1. Comment The title compound [W(Cl) 2 (NO)(dmpe) 2 ](Cl) (I) was obtained by the reaction of [W(Cl) 3 (NO)(NCCH 3 ) 2 ] with 2.5 equivalents of dmpe at room temperature in tetrahydrofurane. The tungsten center has transformed into a seven coordination environment and exhibits a distorted pentagonal bipyramidal geometry, where the four phosphorus atoms and one chloride form the pentagon, and the trans nitrosyl and chloride ligands are at the apexes ( Figure 1). This geometry is clearly different to that observed for the related compound Mo(Cl) 3 (NO)(PMe 3 ) 3 , for which the coordination polyhedron is described as a capped-octahedron (Carmona et al., 1989). The five equatorial atoms, P1, P2, P3, P4, and Cl1 are in an approximately planar array and the corresponding equatorial angles are in the range 68.5 -76.5°. The two Cl -W-P bond angles of 68.84 (4) and 68.56 (4)° are smaller than the theoretical average angle of 72°, while all three P-W-P angles are larger (73.07 (4) -76.49 (3)°). The nitrosyl group is located trans to one chloride ligand and they are positionally disordered in a ratio 0.6:0.4 (Chen et al., 2007). One chloride ion acts as a counterion and is not coordinated, resulting in a tungsten center in the oxidation state +2.

S2. Experimental
[W(Cl) 2 (NO)(dmpe) 2 ]Cl was prepared from complex [W(Cl) 3 (NO)(CH 3 CN) 2 ], which is easily synthesized by the reaction of W(Cl) 6 with NO gas in dichloromethane in the presence of acetonitrile at room temperature (Bencze & Kohàn, 1982;Hunter & Legzdins, 1984). 5.00 g (12.6 mmol) of WCl 6 and 1.32 ml (25.2 mmol) of acetonitrile were dissolved in 180 ml of dichloromethane in a 500 ml three-necked flask. Nitric oxide was passed through the solution, which was stirred at room temperature until the dark purple colour of the solution turned to the light green precipitate after ca 1 h. The volume of the final mixture was reduced to 50 ml in vacuo and the mixture was then cooled to 0°C for 15 min. The precipitate was isolated by filtration and the collected solid was washed with cold dichloromethane (2 x 10 ml at 0°C) and then with hexane (4 x 20 ml) at room temperature. Final drying of the solid under vacuum for 18 h afforded the yellow-green was dissolved in 20 ml of tetrahydrofurane in a Young tap Schlenk and the dmpe ligand (0.38 ml, 2.20 mmol) was syringed into the solution. After 24 h of stirring at room temperature, the solution was filtered off and the solvent was removed under vacuum. The resulting precipitate was extracted with dichloromethane and crystallized in dichloromethane at room temperature to give yellow crystals of compound (I).

S3. Refinement
The H atom were included in calculated positions and treated as riding atoms with C-H distances = 0.98 -0.99Å and U iso (H) = 1.2U eq (C) for CH 2 and 1.5U eq (C) for the CH 3 groups. A positional disorder was refined for the trans NO and Cl ligands with occupancy factors of 0.6:0.4.

Figure 1
View of the molecular structure of (I) with the atom-labeling scheme (displacement ellipsoids are drawn at the 30% probability level). The disordered atoms N12, O12 and Cl22, and all hydrogen atoms have been omitted for clarity.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > σ(F 2 ) is used only for calculating R-factors(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (