Synthesis, crystal structure and reaction of differentially ring-substituted titanocene dichlorides
SummaryA new class of differentially ring-substituted titanocene dichlorides of the type Cp′Cp″TiCl2 has been prepared by reacting Cp″M (M=Li, K; Cp″=RC5H4) with Cp′TiCl3 (Cp′=MeOCH2CH2C5H4). The crystal structure of Cp′(PhCEt2C5H4)TiCl2, the first example, has been determined by x-ray diffraction and refined to a final R factor of 0.0532 for 2304 reflections. The crystal belongs to the monoclinic space group C2h5−P21/c with unit cell parameters:a 10.205(6),b 13.003(5),c 17.591(9) Å, β 101.91(4)°, V=2284 Å3, Z=4 and Dc=1.32 g/cm−3. Replacement of one neomenthyl in bis(neomenthyl-cyclopentadienyl)titanium dichloride by one MeOCH2CH2 — raises the e.e. value from 5.8% to 11.2% in the catalytic asymmetric hydrogenation of 2-phenyl-1-butene.
Syntheses, structures and reactions of some new benzyl-substituted cyclopentadienyl titanium complexes
Twenty eight new benzyl-substituted cyclopentadienyl titanium complexes have been synthesized. Among them, five typical molecular structures have been studied by X-ray analysis. It was found that in the preparation of ortho -MeO-containing benzyl-substituted titanium complexes, when both two substituents on benzylic carbon atom are Et or more large group, titanoxacycle complexes are always formed. The cyclization was promoted by the presence of halides. The activity order of halides for the cyclization is: LiI-NaI > LiBr-Br 2 > NaBr-KI > KBr > I 2 . High temperature is favourable to the cyclization. At 80°C, the normal ortho -MeO benzyl-substituted cyclopentadienyl titanium complex 26 may be spontaneously converted into metallocyclic complex 19 . The position of the MeO group on the benzene ring is the key factor to the cyclization. In the case of meta - and para -MeO benzyl-substituted titanium complexes 23 and 25 , there was no possibility to form a titanoxacycle complex, such as 19 , because the MeO group is too far from titanium. A probable mechanism involving a four-membered transition state was proposed.
AN INTRODUCTION T O THE SOILS OF THE SOUTH-EASTERN PORTION OF THE AUSTRALIAN ARID ZONE
Summary 
 
Seven soil regions, each of which is dominated by soils belonging to one or two great soil groups, are defined and mapped. The outstanding feature is the presence of a variety of soils with widely differing characteristics. The soils are deeper, have more profile differentiation and are finer-extured than those in most-arid regions and are frequently overlain by currently-forming deposits of wind-transported materials. Because the vegetative cover is better developed and there are only small areas of rocky hills and bare rock pediments, water erosion and deposition are not as prominent as in other arid areas.