Ligand-alkoxide compounds, mixed

Reaction of the metal ethoxide [M(OEt)2(HOEt)4] with the desired /3-diketone has been used as an anhydrous method to Group 2 /3-diketonates and mixed ligand/3-diketonate-alkoxide compounds. Presumably, the liberated HOR has a lower binding ability compared to liberated H20. Drake et al. have prepared [Sr3(tmhd)6(Htmhd)] and [Ba4(tmhd)8] by the reaction of Eq. (19).177 Equation (20) gives the generalized reaction for formation of mixed ligand compounds of formula [M(X)n(OR)2 ]) .184185... 

A variety of mixed ligand/alkoxide uranium(V) products are also isolable. Substitution compounds (U(0R)4L, U(0R)3L2, U(0R)2L3) were prepared from the reactions of U(OCH2CH3)5 with FlCl, /3-ketoesters (2,2,2,-trifiuoroaceto acetate, methyl acetate, ethyl acetate), acetyl chlorides... 

Mixed anion compounds can be obtained by metathesis reactions or alcoholysis reactions as previously described. One of these, Ca(N (SiMe3)2)(clox)(THF)3, is particularly interesting in that it has both an alkoxide and amide ligand in the same molecule and is also monomeric... 

Lanthanides react with fatty acids such as lauric, palmitic and stearic acids to give compounds of the formula Ln(COOR)3. Lanthanide alkoxides react with fatty acids to yield mixed ligand soaps, [Ln(OR)A ], where A is a fatty acid. Reaction of [Ln(OR)A ] with acetyl chloride or acetyl bromide yield lanthanide chloride- or bromide-mixed soaps. The spectral characteristics of the alkoxide-mixed soaps, chloride-mixed soaps, bromide-mixed soaps and quaternary-mixed soaps of Pr(III) and Nd(III) were studied and the spectral parameters were evaluated by regression analysis. The intensification of the bands and the nephelauxetic effect were in the order quaternary soaps > alkoxide soaps > chloride-bromide-mixed soaps. The above order is in agreement with the calculated covalency due to the lowering of coulombic interaction parameters as well as the lower melting points of the mixed soaps. 

Kaminsky showed that the catalytic activity of CpTiF3 is better than that of CpTiCl3 [20]. The chloride ligand and the electron-withdrawing alkoxide, O/C3HF6, decrease the conversion. The catalyst activity of all these systems is increased by the addition of triisobutylaluminum (TIBA) to the MAO-Ti complex mixture. By the addition of TIBA, all a-ligands are found to be substituted and the activity of the final catalyst system is practically the same. The ESR spectra of mixed solutions of Cp Ti compounds, MAO and TIBA supported this hypothesis (Figure 17.3) [21]. 

Mixed-ligand precursors are also frequently employed in CSD processing. For example, titanium tetraisopropoxide, which is too reactive to be directly employed in most CSD routes, may be converted into a more suitable precursor by a reaction with either acetic acid or acetylacetone (Hacac). Such reactions are critical in dictating precursor characteristics and have been studied extensively. - Using these reactions, crystalline compounds of known stoichiometry and structure have been synthesized that may subsequently be used as known precursors for film fabrication.Mixed-hgand molecules (carboxylate-alkoxide and diketonate-alkoxide ) represent complexes that are not easily hydrolyzed. A typical structure for one of these compounds is shown in Figure 27.3e. 

Actinide(IV) alkoxide complexes have been reported which are coordinated by a variety of other bulky ligand sets. Uranium(IV) amido compounds are reagents for the preparation of homoleptic uranium(IV) alkoxides as well as mixed alkoxide/amido species. A variety of mixed aryloxide-diethylamide derivatives have been pr ared including (U(NEt2)(0-2,6-Bu 2C6H3)3 and U(NEtp(0-2,6-R7CftH3)3. R = Pr . Bu ). The previously described metallacycle... 

This strategy was adopted to alleviate tedious techniques of mixing multicomponent precursors with different properties. In view of their technological demands, tin(II) heterometallic alkoxides are the most studied class of compounds and their properties can be modulated by chelating ligands like /3-diketonates, carboxylates, and functionalized alkoxides for specific purposes. These compounds also facilitate the formation of oxoalkoxides, either by hydrolysis or by some side reactions. 

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