Methylzinc methoxide

FIGURE 81. Solid state structure of tetrameric methylzinc methoxide... 

Also, the structures of two organozinc pivaloylacetone derivatives associated with methylzinc methoxide or phenylzinc phenoxide were determined by X-ray crystallography. The complex structures of these compounds, Et2Zn4(Pac)4(OMe)2 (175) and Ph2Zn4(Pac)4(OPh)2 (176) (Pac = pivaloylacetone anion), are shown schematically in Figure 87. 

The products, if monomeric, would still possess donor and acceptor sites thus MeZnOMe monomer would have two oxygen lone pairs and two acceptor orbitals on zinc. Association therefore occurs to form oligomers or, in some cases, polymers. The structures of the methylzinc methoxide tetramer and of the dimer (MeZnNPh ) illustrate this well (p. 58). Hydrolysis of an alkyl is probably generally initiated by adduct formation. The hydrolyses of MejB and of MOjAl are... 

Moseley and H.M.M. Shearer, Chem. Comm., 1966, 876.) (b) Crystal structure of methylzinc methoxide tetramer (After H.M.M. Shearer and C.B. Spencer, Chem. Comm., 1966, 194). [EtZnCl] and [EtZnBr] are similar, (c) Crystal structure of [MeZnNPh2l2- All the angles in the four-membered ring are right angles. (After N.A. Bell, H.M.M. Shearer and C.B. Spencer, Acta Cryst, 1983 C39, 1182). 

Similar to beryllium n-diaUcoxides, zinc dialkoxides are also insoluble and nonvolatile compounds. " " The alkylzinc alkoxides are, however, less polymeric and exhibit higher volatility. For example, the cryoscopic molecular weight determination in benzene indicates that methylzinc methoxide and terf-butoxide as well as ethylzinc tert-butoxide are tetrameric" with sublimation temperatures of 60, 95, and 105°C, respectively under 0.0001 mm pressure. ... 

Figure 22. Crystal structure of methylzinc methoxide tetramer. (After H. M. M. Shearer and C. B. Spencer, Chem. Comm., 1966,194).

Methylzinc methoxide itself disproportionates slowly in solution, forming free dimethylzinc and a soluble methoxy-rich species, but (MeZnOPr 4 and (MeZnOBu )4 are free from this complication. 

The thermal decompositions of MeZnOgR (R = Me or Bu ) and MeCdOaBu in hydrocarbons are heterolytic processes that give rise to R0Zn0CH(0)Zn0 and MeCdOCH(0).CdO as the major products.Methylzinc methoxide, from McaZn and MeOH in hexane at — 70 °C, is tetrameric in the solid state and also in benzene solution. The crystal structure consists of Zn and O (both 4-coordinate) set at alternate corners of a distorted cube [Zn-O av. 200 and Zn-C 195 pm]. 

As with oxoanion salts, a number of interesting structures are found with simple organic species as ligands, for example, a crystal-structure determination of the tetrameric methylzinc(II) methoxide, MeZn(OMe) 4, reveals the structme (4) in which zinc and oxygen are each tetrahedrally coordinated. Closely related to this stractme is that of the polymerization catalyst Zn(OMe)2(EtZnOMe)6 (5). The complex is centrosymmetric and consists of two... 

In the absence of propane, the interaction between methane and zeolite Zn/HBEA yields methylzinc (ZnCHj) and methoxide (ZnOCHj) species and formate fragments, which undergo further conversion into acetaldehyde and acetic acid (Fig. 29D). In the presence of benzene, only the formation of the methoxide ZnOCH is observed, which is apparently not oxidized by oxygen of the defected ZnO structure (Fig. 29E). At 823 K, benzene is methylated by ZnOCHj, yielding methyl-substituted aromatics, namely, toluene and xylenes (Fig. 29F). It was thereby found that methane participated in the methane-propane co-aromatization reaction hy alkylating the aromatic compounds that resulted from propane, as is illustrated hy Scheme 7. 

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