STRUCTURAL STUDIES OF SOME ORGANOTITANIUM(IV) COMPLEXES

Andrej Pevec

Faculty of Chemistry and Chemical Technology, University of Ljubljana,

Aškerčeva 5, 1000 Ljubljana, Slovenia; E-mail: andrej.pevec@fkkt.uni-lj.si

The chemistry of organometallic complexes with monocyclopentadienyl derivatives plays a major role in many areas of research. For instance, the large clusters based on fluoride-bridged organometallic units provide the opportunity to isolate inorganic solids such as NaF, Li₂O, or CaF₂, which otherwise exist only as a large three-dimensional aggregates.¹ Complexes [Ti(C₅H₅)F₃], [Ti(C₅H₄Me)F₃] and [Ti(C₅Me₅)F₃] in combination with methylaluminoxane [(AlMeO)_n] display high catalytic activity in the polymerization of styrene.² More recently, there has been considerable interest in the synthesis and structure of metal phosphonates due to their potential application in the area of catalysis, sorption, ion exchange, sensors, proton conductivity, intercalation chemistry, photochemistry and materials chemistry.³

In this lecture, some bimetallic organotitanium complexes with in situ generated metallic fluorides into [Ti(C₅Me₅)F₃] will be described. The range of possible host-guest compounds spans from simply encapsulation of metallic ion (Li⁺, Ca²⁺, Sr²⁺) to larger aggregates with the metal-titanium-fluorine core (Sr²⁺, Ba²⁺). The synthesis and characterization of titanophosphonate cage compounds with a rattling fluoride ion within the cage will also be reported. The refinement of mixed fluoro-oxo titanium(IV) cyclopentadienyl complexes can cause problems due to ambiguity in distinguishing between oxygen and fluorine atoms. Some other methods of characterization (e.g. NMR spectroscopy), have a powerful meaning in the final crystal structure determination.

References:

1.    E. Murphy, R. Murugavel, H.W. Roesky, Chem. Rev. 1997, 97, 3425-3468.

2.    W. Kaminsky, S. Lenk, V. Scholz, H.W. Roesky, A. Herzog, Macromolecules 1997, 30, 7647-7650.

3.    A. Clearfield, Prog. Inorg. Chem. 1998, 47, 371-510.