Trichlorido(tetrahydrofuran){(1,2,3,3a,7a-η)-1-[2-(1-trimethylsilyl-1H-imidazol-2-yl-κN 3)-1-methylpropyl]indenyl}zirconium(IV)

The title compound, [ZrCl3(C19H25N2Si)(C4H8O)], was prepared from bis(N,N-dimethylamido-κN)(2-{2-[(1,2,3,3a,7a-η)-indenyl]-2-methylpropyl}-1H-imidazolido-κN 1)zirconium(IV) [(C16H16N2)Zr(NMe2)] by reaction with excess Me3SiCl in tetrahydrofuran (THF) at elevated temperature. The crystal studied contained a minor non-merohedral twin contaminant [6.3 (4)%] which was taken into account during the refinement. The coordination polyhedron of the ZrIV atom is a distorted octahedron [assuming that the five-membered ring of the indenyl group (Cp) occupies one coordination site], with the Cp group and a THF O atom at the apical positions and the three Cl and ligating N atoms at the equatorial positions. The Zr, Si and the methylene C atoms deviate noticeably from the imidazole ring plane [by −0.197 (5), −0.207 (5) and 0.119 (6) Å, respectively]. The THF ligand adopts an envelope conformation.

Financial support from the National Natural Science Foundation of China (project Nos. 20702041 S. Guan, W. Nie and M. V. Borzov
The coordination polyhedron of the Zr-atom in I is a distorted octahedron [assuming that the five-member ring of the indenyl group (Cp) occupies one coordination site], with the Cp-group and O-atom of the tetrahydrofuran (THF) molecule at the apical positions and the three Cl-and ligating N-atoms at the equatorial ones (Fig. 1). The Zr-, Si-and the methylene group C-atoms noticeably deviate from the imidazole ring plane [by -0.197 (5), -0.207 (5) and 0.119 (6) Å, respectively].
Indenyl group is planar within 0.06 Å. The THF ligand adopts an envelop conformation.
Among them, there are two dinuclear structures where two Zr-atoms are linked with two bridging µ-Cl-atoms (Enders et al., 1996 andNie et al., 2008; in both cases Zr-atoms exhibit CN 6), two monomeric complexes with a pentacoordinated Zr centre (Nifant'ev et al., 1998 andKrut'ko et al., 2004), and, finally, three monomeric complexes with a hexacoordinated Zr centre (Paolucci et al., 2003;Krut'ko et al., 2004;Krut'ko et al., 2007). Of interest and despite of the different nature of the "sixth" n-donor ligand opposing the Cp-group [a tetrahydrothiophene molecule (Krut'ko et al., 2004), a pyridine molecule (Krut'ko et al., 2007), or a pendant OH-group (Paolucci et al., 2003)], the structural motif of the latter three complexes is very similar to that of I. As for the nature of the Cp-type ligand, only one case among all the mentioned above corresponds to an indenyl group (Nifant'ev et al., 1998).

Refinement
The sample crystal of I contained a minor non-merohedral twin contaminant [dominant to minor component transform twin law (matrix row by row): 0.94452 -0.10595 -0.05098 0.07590 1.01441 -0.03026 0.08528 0.09700 1.02798]. The absorption correction was processed with TWINABS (Sheldrick, 1996). The contribution of the minor component was estimated to be 5.55%. The structure was then solved with the detwinned HKLF 4 data file and finally refined with the HKLF 5 format data file with only single and composite reflections relating to the main component included and merged according to the point group -1 [the BASF parameter converges to 0.063 (4)]. Non-H atoms were refined anisotropically. H atoms were treated as riding atoms with distances C-H = 0.96 (CH 3 ), 0.97 (CH 2 ), and 0.93 Å (C Ar H) and U iso (H) = 1.5 U eq (C), 1.2 U eq (C), and 1.2 U eq (C), respectively. Fig. 1. Unsymmetrical unit of I with labeling. Thermal ellipsoids are shown at the 50% level of probability. All H-atoms are omitted for clarity. The Zr1 to Cp-centroid bond is depicted as a dashed line.

supplementary materials sup-4 Figures
Crystal data [ZrCl 3 (C 19  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 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.

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