Titanium aluminate complexes

In the course of these studies key features such as olefin coordination [19,20], olefin insertion (propagation) [16,21,22], /(-hydrogen elimination [16,21,22], and /3-alkyl elimination [23] could be spectroscopically and structurally proven. In particular, yttrium aluminates have been proposed to model isoelectronic cationic homo- and heterobridged Zr/Al heterobimetallic complexes as dormant species and potential polymer chain transfer candidates [24]. Such zirconium aluminate complexes seem to be elusive [25], while the first structurally characterized titanium alumi-... 

Alkenes can be converted into primary alkyl acetates via titanium-catalysed hydroalumination (Scheme 2) followed by lead tetra-acetate oxidation of the dialkyldihydroaluminate addition products (2). Only two equivalents of alkene are used per aluminium atom as it seems that only two alkyl groups from the aluminates can participate in the oxidation. In a closely related study a titanium-boron complex has been found to promote catalytic hydroboration of alkenes (also Scheme 2) cw-addition predominates for non-terminal alkenes. The adducts (3) can be oxidized to alcohols, and it may be seen that both sequences provide anti-Markovnikov products. 

Preparation.—Alcohols can be obtained from terminal alkenes by hydro-alumination with lithium aluminium hydride in the presence of a titanium complex, followed by oxidative cleavage of the adduct (Scheme 1). The sequence provides anti-Markovnikov alcohol. 

The three main groups of commercial complex inorganic color pigments are titanates, which use a titanium dioxide base, aluminates, which use an aluminum oxide base, and chromites and ferrites, which have chromium and/or iron oxide bases. Some important complex inorganic color pigments are listed in Table 3.4. 

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