The molecular structure of the mixed chloro-iodo-titanium(II) complex, (η 6-durene)Ti[(μ-X) 2(AlX 2)] 2 (X = Cl, I); the distribution of the halogen atoms in the bridge and the outer positions

Abstract

The titanium(II) complex (η 6-durene)TiAl 2Cl 8−yI y (II) crystallizes in the rhombic space group Pna2 1 with Z = 4 and lattice parameters a 19.949(6), b 9.146(4), c 13.883(7) Å. The titanium atom in II possesses square pyramidal coordination similar to all of the known structures of arenetitanium(II) complexes; four halogen atoms form the corners of a square and the π-bonded durene takes the axial position. An X-ray diffraction study gave a value of y = 3.25 for II. The halogen ligands were not randomly distributed: about 85% of the iodine ligands were found to be in the outer positions. The aromatic plane of apical 1,2,4,5-tetramethylbenzene (durene) is nearly parallel to the plane of the bridging halogen (largely chlorine) atoms; the durene molecule is oriented so that the pseudosymmetrical plane of the complex through the Al(1), Ti and Al(2) atoms bisects the C(1)C(2) and C(4)C(5) bonds. The methyl groups are bent by an average of 0.18 Å above the aromatic ring plane.