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

摘要

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(mm(2)), C-s(m) and C-1(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(ipso)1-Centroid1-Centroid2-C(ipso)2) of φ = 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 &ANGS;) 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) &ANGS; for CN, CF3 and CH3 groups, respectively. The CN groups as well as the H atoms lie out of the C-6 ring planes and are bent towards the Cr atom, but the C atom of the CH3 group also lying out of the C-6 ring plane is bent away from the Cr atom. The C atom of the CF3 group is essentially coplanar to the C-6 ring plane. There are no unusual intermolecular contacts in the structures of (2)-(4).