Multiple bonding in four-coordinated titanium(IV) compounds.

Theoretical description (MP2/6-311G* and B3LYP/6-311G*) is presented for hypovalent titanium alkoxide model compounds showing linear angleTi-O-C angles. This feature is explained by the existence of a polarized triple Ti-O bond. In contrast, a series of 18 electron germanium derivatives displaying bent angleGe-O-C angles contain polarized single Ge-O bonds. The nature of the Ti-O and Ge-O bonds is established by means of natural bond order, atoms-in-molecules theory, and electron localization function analyses.