Organic Oxygen Donor Complexes

Organic Oxygen Donor Complexes.—Zinc chloride reacts with the N,0-chelate 

Demura, T. Kawamoto, and H. Kanatomi, Bull. Chem, Soc. Japan, 1975,48,2820. 

The crystal structure of the polymerization catalyst Zn(OMe)2(EtZnOMe)g (11) has been determined. The centrosymmetric complex consists of two enantiomorphic 

Hunter, G. A. Rodley, and K. Emerson, Inorg. Nuclear Chem. Letters, 1976,12, 113. 

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Another type of ligand is the monoanionic, tridentate oxygen donor [(C5H4R)Co-(P(0)R R")3] (Lor), which has been used to prepare the complexes of technetium [37] and rhenium [38] [M03L] and [MOX2L] (X Cl, Br). These complexes are stable in organic solvents but hydrolyse slowly in water. In order to evaluate their usefulness in radioimmunotherapy, the corresponding compounds were also prepared with radioactive rhenium isotopes. 

Undissociated acids form adduct complexes with organic compounds, containing oxygen donor atoms. If the adducts formed are soluble in... 

Lanthanides in oxidation state (III) form complexes with organic ligands with oxygen donor groups and some data for Eu(III) complexes are given in Table 11.24. 

Chiral epoxides are important intermediates in organic synthesis. A benchmark classic in the area of asymmetric catalytic oxidation is the Sharpless epoxidation of allylic alcohols in which a complex of titanium and tartrate salt is the active catalyst [273]. Its success is due to its ease of execution and the ready availability of reagents. A wide variety of primary allylic alcohols are epoxidized in >90% optical yield and 70-90% chemical yield using tert-butyl hydroperoxide as the oxygen donor and titanium-isopropoxide-diethyltartrate (DET) as the catalyst (Fig. 4.97). In order for this reaction to be catalytic, the exclusion of water is absolutely essential. This is achieved by adding 3 A or 4 A molecular sieves. The catalytic cycle is identical to that for titanium epoxidations discussed above (see Fig. 4.20) and the actual catalytic species is believed to be a 2 2 titanium(IV) tartrate dimer (see Fig. 4.98). The key step is the preferential transfer of oxygen from a coordinated alkylperoxo moiety to one enantioface of a coordinated allylic alcohol. For further information the reader is referred to the many reviews that have been written on this reaction [274, 275]. 

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