Zirconium alkoxides structure

Zirconium, tetrakis(acetylacetonate)-stereochemistry, 1, 32, 94 Zi rconium, tris(phenylenedithio)-structure, 1, 63 Zirconium alkoxides oligomeric structure, 2,346 Zirconium chloride... 

Peercy, P.S., Dosch, R.G., and Morosin, B., "Preparation and Structural Studies of the Hydrolysis Products of Titanium, Niobium and Zirconium Alkoxides," SAND76-O556, Sandia Laboratories, Albuquerque, NM (1976). 

On the basis of H NMR data it has not been possible to make any definite conclusions concerning the structures of oligomeric titanium and zirconium alkoxides. At room temperature only one set of CH2CH3 signals was observed for [Ti(OEt)4]4 and although the presumably rapid... 

In the case of organic derivatives such as zirconium acetate, direct bonding of the carboxyiate to the zirconium is found. Similar structures are also found in solvent-soluble, water-insoluble carboxylates such as zirconium propionate. Zirconium alkoxide derivatives tend to be monomeric in solvent-based systems but hydrolyse rapidly with ambient water to give polymeric species. 

Note that the structure shown in Fig. 67, is the first zirconium alkoxide with a M4(OR)16 edge-shared bioctahedral geometry (441). 

Peter D, Ertel TS, Bertagnolli H. EXAFS study of zirconium alkoxides as precursor in the sol-gel process I. Structure investigation of the pure alkoxides. J Sol-Gel Sci Technol 1994 3(2) 91-9. 

The synthesis of zirconia nanomaterials by a one-step sol-gel route under supercritical C02(l) drying using zirconium alkoxides and acetic acid was reported by Sui et al. [24]. Their materials exhibited high surface areas (up to 399 m /g) and porosity, while the calcined materials demonstrated tetragonal and/or monoclinic nanocrystallites. Either a translucent or opaque monolith was obtained. Investigation by electron microscopy showed that the translucent monolithic Z1O2 exhibited a well-defined mesoporous structure, while the opaque monolith, formed using added alcohol as a co-solvent, was composed of loosely compacted nanospherical particles with a diameter of approximately 20 nm. 

As was discussed for silicon precursors (Figure 1.2), closed structures (oxo clusters) can be formed as well by the condensation reactions, and the same remarks apply with regard to their importance in sol-gel processes. Figure 1.8 shows an example of a cluster obtained by hydrolysis of an organically substituted zirconium alkoxide derivative. 

Electrodeposition from sol-gel solutions containing two or more different sol-gel precursors yields hybrid films, as the sol-gel components hydrolyze and condense together forming a cross-linked structure. The hybrid films may be electrodeposited from precursors consisting of either two or more different silanes, or silane with titanium or zirconium alkoxides. 

Recent advances in the development of well-defined homogeneous metallocene-type catalysts have facilitated mechanistic studies of the processes involved in initiation, propagation, and chain transfer reactions occurring in olefins coordi-native polyaddition. As a result, end-functional polyolefin chains have been made available [103].For instance, Waymouth et al.have reported about the formation of hydroxy-terminated poly(methylene-l,3-cyclopentane) (PMCP-OH) via selective chain transfer to the aluminum atoms of methylaluminoxane (MAO) in the cyclopolymerization of 1,5-hexadiene catalyzed by di(pentameth-ylcyclopentadienyl) zirconium dichloride (Scheme 37). Subsequent equimolar reaction of the hydroxyl extremity with AlEt3 afforded an aluminum alkoxide macroinitiator for the coordinative ROP of sCL and consecutively a novel po-ly(MCP-b-CL) block copolymer [104]. The diblock structure of the copolymer... 

It was quite unexpectedly found that the amorphous samples of zirconium and hafnium alkoxides M(OR)4 contain several types of oxocomplexes, particularly, M3O(OR)i0 and M40(0R)14 [1612], The trinuclear Zr3([l3-0)()i3-OBu XOBu ), was isolated in a crystalline form and turned out to be a structural analog of the known isopropoxide clusters of Th, Mo, and U(IV) -MjOCOPr ),) [1520] (see also Sections 4.3 and 12.12). The inclusion of the solvent molecules inside the cavities of the structures and formation of alcohol solvates in many cases leads to microanalysis data that does not deviate much from those calculated for M(OR)n. 

The amides of zirconium and hafnium, M(NR2)4, like the alkoxides, are associated. The degree of association depends on the nature of R. Zr(NMe2)4 (mp 70 °C, bp 80 °C at 0.05 mmHg) in the sohd state adopts the amide-bridged dimeric structure Zr2(/u.-NMe2)2(NMe2)6. A monomer-dimer equilibrium is estabhshed in solution but only the monomer exists in the gas phase. Gas-phase electron diffraction data indicate that the N atoms are coplanar, as a result of N to Zr p to donation seep Bonding). ... 

The metal salts of alcohols are called alkoxides, M(OR), where M is a metal and R is an alkyl group. Typical examples in the synthesis of ferroelectric thin films include titanium isopropoxide [Ti(OPr )4 where Pr represents isopropyl], tantalum ethoxide [Ta(OEt)5 where Et represents ethyl], and zirconium butoxide butanol [Zr(OBu )4 n-BuOH where Bu represents -butyl], an alkoxide/alcohol compound. The structure of this compound, shown in Figure 27.3a, illustrates its dimeric nature, that is, the fact that each molecule contains two metal centers. 

An interesting heterobimetallic alkoxide derivative containing copper(I) and zirconium, Cu2Zr2(O-/-Pr),0, was assigned the Structure XV crystallographi-cally (248), and consists of a Zr2(0-/-Pr)9 face-sharing bioctahedron with two... 

Single metal and mixed metal oxo alkoxides can also be prepared by reaction between metal halides, oxy halides, and alkali metal alkoxides.47,48 One of the first to be structurally characterized was a series of mixed Cd or Sn containing zirconium, tin, and titanium alkoxides.84,85 These and other examples are shown in skeletal form in Figure 3. 

The salt metathesis reaction of sodium fluorenone ketyl with Cp 2ZrCl2 in THF produces the corresponding zirconium fluorenone ketyl complex 856657 which was structurally characterized (Scheme 215). In the case of sodium benzophenone ketyl, further reaction between the ketyl radical and a Cp ligand takes place to give finally the ring-metallated zirconocene bis(alkoxide) complex 857. 

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