The crystal structure of sym-trans-di-a-phenoxyhexaphenoxydiphenolatodititanium(IV), [Ti(OCbHs)4-HOCrHs]2 has been determined by Patterson and heavy-atom methods. The crystal is monoclinic, space group P21/n, with cell constants a= 10"491 (12), b= 18"409 (28), c= 13.858 (17)/~, and r= 101.54 (25) °, containing two dimeric units per cell. Refinement by full-matrix least-squares methods yielded a final R value of 0.081. The dimer, which has two titanium atoms bridged by two phenoxy groups, is located on a center of symmetry. There are three phenoxy Ti-O bond lengths: 1.789 (9), 1.842 (11), and 1.884 (10/~), a phenol Ti-O bond length of 2.200 (11)/~, and two equal phenoxy Ti-O bridging distances of 2.027 (10) and 2"045 (11)/~,. The Ti-O-C bond angles of 168.9 (10) and 175.1 (11) °, found for two of the phenoxy oxygen atoms, are nearly linear. A decrease in the Ti-O bond distances results in a corresponding increase in the Ti-O-C bond angles for the three phenoxy groups. Hydrogen-bonding between the axial phenol and phenoxy oxygen atoms is suggested by the short oxygen-oxygen contact distance of 2.671 (13) A, the Ti'-Ti-O bond angles of 86"7 and 75-8 °, and the dihedral angle of 1.4 ° between the two planes formed by these atoms.

An X-ray diffraction study of tetraphenoxytitanium@) monophenolate has shown the structure to be dimer of octahedrally co-ordinated alkoxytitanium molecules.

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