Acta Crystallographica Section B

Structural Science

Volume 61, Part 3 (June 2005)

research papers

Acta Cryst. (2005). B61, 304-311 [ doi:10.1107/S0108768105008797 ]

Substituent effects in bis(arene)chromium compounds containing a CN group in the aromatic ring

V. N. Khrustalev, A. Y. Vasil'kov and M. Y. Antipin

Abstract: The crystal structures of Cr(PhCN)₂ (2), (PhCN)Cr(PhCH₃) (3) and (PhCN)Cr(PhCF₃) (4) prepared by means of the Metal Vapor Synthesis (MVS) technique have been determined. Compounds (2), (3) and (4) crystallize as discrete sandwich complexes having intrinsic C_2v(mm2), C_s(m) and C₁(1) symmetries, respectively. The X-ray diffraction study has revealed a synperiplanar conformation for (2) and (3), and a synclinal conformation for (4) with a torsion angle (C_ipso1-Centroid1-Centroid2-C_ipso2) of [varphi] = 63.5°. The angles between the ligand planes are 2.2, 3.9 and 1.8°, respectively. The Cr atom is slightly (by 0.04-0.06 Å) displaced towards the substituents from the line connecting the centers of the opposite aromatic rings. The Cr-C_ipso distances are 2.115 (2)-2.137 (2), 2.112 (2) and 2.185 (3) Å for CN, CF₃ and CH₃ groups, respectively. The CN groups as well as the H atoms lie out of the C₆ ring planes and are bent towards the Cr atom, but the C atom of the CH₃ group also lying out of the C₆ ring plane is bent away from the Cr atom. The C atom of the CF₃ group is essentially coplanar to the C₆ ring plane. There are no unusual intermolecular contacts in the structures of (2)-(4).

Keywords: sandwich complexes; stereochemistry; substituent effect.


	Structure factor file (CIF format) (149.4 kbytes) Contains datablock 2

	Structure factor file (CIF format) (116.3 kbytes) Contains datablock 3

	Structure factor file (CIF format) (169.4 kbytes) Contains datablock 4

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