Alkoxides metal atom

Metal Alibis and Alkoxides. Metal alkyls (eg, aluminum boron, sine alkyls) are fairly active catalysts. Hyperconjugation with the electron-deficient metal atom, however, tends to decrease the electron deficiency. The effect is even stronger in alkoxides which are, therefore, fairly weak Lewis acids. The present discussion does not encompass catalyst systems of the Ziegler-Natta type (such as AIR. -H TiCl, although certain similarities with Friedel-Crafts systems are apparent. 

The chemistry of ethyl alcohol is largely that of the hydroxyl group, namely, reactions of dehydration, dehydrogenation, oxidation, and esterification. The hydrogen atom of the hydroxyl group can be replaced by an active metal, such as sodium, potassium, and calcium, to form a metal ethoxide (ethylate) with the evolution of hydrogen gas (see Alkoxides, metal). 

Compound (6) has the structure shown in Fig. 4(d). It formally has 14-electron configurations about each metal atom and all fourteen electrons are involved in the bonds represented by lines in the structural drawing. Either the U2-CO group makes no appreciable demand for tt electron density or there may be an indirect feeding of electrons from the lone-pair orbitals of the alkoxide groups to y2-C0. Alkoxide groups are known to be 7r-electron donors. 

The partial hydrolysis of the metal organic compound (e.g. a metal alkoxide) introduces the active functional OH groups, attached to metal atoms. 

Heterocycles treated in this section belong to several structure types. The metal atoms in compounds under discussion can exist not only in the tetravalent but also in the carbenoid divalent state and the heterocycles differ not only in the nature and number of metal atoms but also in the nature of ring bonds of the latter. Thus, besides conventional organometallic compounds having only M—C bonds there are heterocycles with M—M bonds and those with C—M—X or X—M—Y fragments (X and Y—common heteroatoms like O, S, N). The last type is the most numerous and important group of five-membered Ge-, Sn- and Pb-heterocycles in which the metals are involved in M—X and M— Y bonds similar to those in respective metal alkoxides, thiolates and amides. This feature not only affects the structural parameters of these compounds but determines their chemical properties, synthetic routes and applications. 

The development of metal atom vapor technology over the last 15 years has made available to the chemist a new and useful synthetic technique. A number of novel transition metal compounds have been isolated by the method, particularly in the field of organometallic chemistry. However, the use of vaporized metal atoms for the synthesis of metal alkoxides and phenoxides by condensation into the neat alcohol has been only briefly mentioned in the literature.27... 

In the case of the alkoxides and phenoxides of molybdenum(III) the interaction between metal atoms becomes dominant, leading to diamagnetic compounds of stoichiometry Mo2(OR)6 or Mo4(OR )i2(R/ = the less bulky Me or Et).78 These compounds are readily sublimable, (70-90 °C/ 10-3 Torr for Mo OPr1 ) and retain either their dimeric or tetrameric nature both in solution and the gas phase, as determined by cryoscopic measurements and mass spectrometry, respectively.78 An analogous tungsten(III) complex W2(OBu )6 can be obtained, but for other alkoxides the simple homoleptic compounds cannot be isolated.79,168... 

In some cases, alkoxide displacements at a metal center proceed sequentially and at different rates so that, if redistribution processes do not intervene, mixed diketonates can be obtained by adjusting the ratios of reactants.190,191 Recently, bimetallic / -diketonates of the type M2(diketonate)2(OR)4 (M = Mo, W R = alkyl) have been prepared from diketones and M2(OR)6. X-Ray studies show that one diketonate is attached to each metal atom so that unbridged M=M units are retained although rapid rotation about this multiple bond can occur.192 Diketonate complexes with metal-metal multiple bonds are rather uncommon, one other example being C2v CK-Mo2(Me-COCHCOMe), (02 CMe)2.193... 

Metal alkoxides react rapidly with water. This is due to the presence of electronegative alkoxy groups, which make the metal atoms highly prone to... 

In 1950s and 1960s Bradley developed the structure theory for metal alkoxides, based on the principle that metal atoms should achieve maximal coordination at minimal molecular complexity of the aggregate, [M(OR) ]m. 

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