Metal fluoroalkoxides

The ammoniate of the products in Eq. 112 originates from the reaction of the acidic fluoroalcohols with the (Me3Si)2NH produced during the formation of the metal fluoroalkoxides ... 

Despite the fact that metal fluoroalkoxides of many metals are known (Section IV.B.l), relatively few chloroalkoxide derivatives have been reported (351,... 

Y. Chi, S. Ranjan, P.W. Chung, H.Y. Hsieh, S.M. Peng and G.H. Lee, AlkaUne-earth metal fluoroalkoxide complexes with multi-coordinated polyether appendage synthesis and characterization, Inorg. Chim. Acta, 334, 172-182 (2002). 

An example of a much faster catalyst, equally well characterised is depicted in Figure 16.11. This catalyst gives thousands of turnovers of cis-2-pentene in a few minutes at 25 °C. The electron withdrawing fluoroalkoxides make the metal centre nucleophilic and the steric bulk prevents dimer formation or other degradation reactions. 

Among the derivatives of halide-substituted alcohols the fluoroalkoxides are of special interest. The presence of peripheral fluorine atoms enables the secondary M...F interaction and filling of the coordination sphere of the metal, which leads to an unusually high volatility. These compounds are described in the review by Willis [1749]. 

MoO[OC(CF3)3]4 (327), WF5(ORf) [Rf = CH2CF3, CH2CH2CF3, and CH(CF3)2) (328)] (by the reactions of the corresponding metal chlorides with alkali metal (generally lithium) fluoroalkoxides), were prepared during 1975-1980. 

By mistake, sodimn was added to excess liquid perfluoroalkylmethanol in the absence of tire diluent which had previously moderated the reaction. Vigorous initial reaction culminated in an explosion which destroyed the flask and attached glassware and cracked tire fume cupboard window, this was attributed to ignition of evolved hydrogen [1]. Since air would rapidly be swept from the flask by the gas flow, it seems probable that a hydrogen explosion sufficient to damage the hood would be external to the reaction flask. The desired fluoroalkoxide is undoubtedly thennodynamically imstable with respect to sodium fluoride formation and a number of other metal derivatives of fluorinated organics have proved explosively metastable [2]. 

The sodium method has been successfully employed for the synthesis of a triply metal-metal bonded fluoroalkoxide of molybdenum (Eq. 2.55). °... 

Alkaline earth and REfluoroalkoxides ([M(OR) ], where M = metal elements and OR = fluoroalkoxo groups) were examined as precursors for metal fluorides in the sol-gel process (Poncelet, 1998 Chi, 2002). Such fluoroalkoxides were prepared by the reaction of polyether-substituted flouroalcohols with metal source reagents, Sr(OC3H7)2 orBaH2. It was possible to obtain pure metal fluoride powders by hydrolysis or pyrolysis of the precursors. 

Direct metallation via anhydrous ammonia activation has been used to successfully prepare cyclopentadienides [244—246], fluorenyls [247], amides [112, 113, 223], pyrazolates (Eig. 11) [112], anthracenides [249], alkoxides [250], aryloxides [251-254], fluoroalkoxides [123], thiolates [196, 255-257], silanides [258], siloxides [250], selenolates [255, 256], and a rare methanide, Ba[(PhCH (C5H3N-2))]2(diglyme)(thf) [259]. Sparsely soluble ammonia adducts of the... 

Studies on OCH(CF3)2, OCMe(CF3)2, OCMc2(CF3), and 0C(CF3)3 derivatives of the alkali metds, alkaline earth metals, transition metals, and the lanthanide elements are reviewed, with emphasis on work reported since 1988. Alkali and alkaline earth fluoroalkoxides are generally made from reaction between the alcohol and the metal, its hydride, or organometallics. Most syntheses of transition metal derivatives involve reaction between metal halides and alkali or alkaline earth salts, or the alcoholysis of metal alkyls, alkoxides and amides. Coordination between organic fluorine and electropositive metals (ie. Na, Ba, Tl, Pr) is often observed in the crystal structures of these fluoroalkoxides and may be related to their use as chemical vapor dqx)sition precursors for metal fluorides. 

Copper and silver fluoroalkoxides have been synthesized by primarily two methods. One method, ionic metathesis in ether solvents between al or alkaline earth salts and a copper or silver halide, usually results in a double metal alkoxide product. A second method, alcoholysis of organometallics or unfluorinated alkoxides avoids the presence of other metals but can result in mixed... 

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