Alkoxide ligand

The alkoxides and aryloxides, particularly of yttrium have excited recent interest. This is because of their potential use in the production of electronic and ceramic materials,in particular high temperature superconductors, by the deposition of pure oxides (metallo-organic chemical vapour deposition, MOCVD). They are moisture sensitive but mostly polymeric and involatile and so attempts have been made to inhibit polymerization and produce the required volatility by using bulky alkoxide ligands. M(OR)3, R = 2,6-di-terr-butyl-4-methylphenoxide, are indeed 3-coordinate (pyramidal) monomers but still not sufficiently volatile. More success has been achieved with fluorinated alkoxides, prepared by reacting the parent alcohols with the metal tris-(bis-trimethylsilylamides) ... 

Ligand A anionic (e.g., halides, pseudohalides, alkyl, aryl, thiolate, alkoxide) ligand N neutral (e.g., amines, imines, phosphines, carbenes, nitriles, isonitriles, NO, CO) ligand C cationic (e.g., NO+)... 

Diorganoboryloxides, R2BO, bearing bulky organic substituents are quasi-alkoxide ligands for main group and transition metals. Because of the 7r-acceptor properties of boron, these anions are weaker 7r-donors than alkoxides, and this is reflected in their structural chemistry. Diethylzinc reacted with the borinic anhydride (9-BBN)20, Scheme 82, to afford the alkylzincboryloxide [EtZnO(9-BBN)]4 129, which also crystallizes in heterocubic form.187... 

R.R. Schrock, M.I.T. Have you or anyone else prepared platinum(IV) metallacyclobutane complexes with alkoxide ligands in place of chlorides One might expect the alkoxide complexes to behave considerably differently than the chloro complexes, perhaps like early transition metal complexes. 

There had been some evidence that alkoxide ligands slow down reactions which involve elimination of a p-hydride from an alkyl ligand. a-01efins are dimerized to a mixture of head-to-tail and tail-to-tail dimers by olefin complexes of the type Tafr -CsMes)-(CH2=CHR)Cl2 (10). The p,p1- and a,p -disubstituted tantalacyclo-pentane complexes are intermediates in this reaction. Their decomposition involves the sequence shown in equation 5. When one... 

These studies demonstrate that two alkoxide ligands can take the place of an oxo ligand and that aluminum halides, by coordinating to a halide ligand, can generate an efficient and long-lived catalyst. It is possible that [W(CHR)(0R)2(Br)]+AlBr4- is responsible for the catalytic activity, but at low concentrations, and in the... 

R.R. Schrock We believe so, but the t-but oxide ligand seems to be a unique alkoxide. We have prepared tungstenacyclobutadiene complexes containing other alkoxide ligands which are stable toward decomposition to an alkylidyne complex. 

Monomeric arrangements are rare for alkoxide complexes of bismuth and require excess anionic ligands or bulky substituents. Otherwise the alkoxide ligands typically impose dimerization or multinuclear clustering, which are expressed in a variety of currently unusual structural arrangements (Table I). 

The key step involves C-H bond activation, and produces a molybdenum complex with hydride and ketone ligands from the alkoxide ligand. Subsequent... 

The most common catalysts for the Meerwein-Ponndorf-Verley reduction and Oppenauer oxidation are Alm and Lnm isopropoxides, often in combination with 2-propanol as hydride donor and solvent. These alkoxide ligands are readily exchanged under formation of 2-propanol and the metal complexes of the substrate (Scheme 20.5). Therefore, the catalytic species is in fact a mixture of metal alkoxides. 

Alkoxide gels, 23 60 Alkoxide gels, in optical fiber manufacturing, 11 145 Alkoxide initiators, 14 259 Alkoxide ligands, thorium, 24 770 Alkoxides, 12 190 25 72-86 controlled hydrolysis of, 23 56 iron, 14 533 mixed-metal, 25 100 titanium, 25 82 uranium complexation with,... 

Microbial resistance to established organic antibiotics is a potentially serious problem and provides an impetus for the development of novel antimicrobial metal compounds. The potency of Ag(I) ions is well known—but how does Ag(I) kill a bacterium Much current attention is focused on Bi(III) on account of its ability to kill Helicobacter pylori, an organism which prevents ulcers from healing. Bis-muth(III) chemistry has many unusual features a variable coordination number, strong bonds to alkoxide ligands, the stereochemical role of its 6s2 lone pair, facile formation of polymers, and dual hard and soft character. 

The carbonylation of (Cp )(77S-C2B9H11)TiMe resulted in an unusual B-H activation, generating novel complexes containing linked carborane-alkoxide ligands.30 However, dicarbollide analogs of the constrained-geometry complex,... 

Alkoxides and imido are used as anionic ligands in zirconium and titanium catalysts for the polymerisation of alkenes, sometimes as the only anions, but often in combination with cyclopentadienyl ligands. Imides linked to cyclopentadienyl groups form part of the single-site catalyst developed by Dow (Chapter 10) (Figure 1.9, 1). In very different titanium catalysts, namely those used for epoxidation of alkenes, also alkoxide ligands are used (Chapter 14). 

The first metallasilsesquioxanes containing metal-metal triple bonds have been reported by Chisholm and Feher et al The reaction between two equivalents of 3 and Mo2(OtBu)6 in benzene or toluene at room temperature (Scheme 54) led to rapid replacement of all six alkoxide ligands and formation of orange, crystalline... 

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