Alkoxides cyclopentadienyl derivatives

It is probable that the cyclopentadienyl derivatives of Ti(IV), [(C5Hs)2Ti( u-OCOC=COCO)]2 (86) and [(C5Hs)2Ti(p-OCOC=COCO)]5-5L (87) (where L is a solvent molecule, dioxane or methylene chloride), obtained in a two-phase system - water/organic solvent) are related to this class of MCM [55]. The compound Zr4[OCOC(CH3)=CH2]io02(OR)2 H2O (n = 2, 4) (88) has been obtained by boiling zirconium alkoxides with acrylic acid [56],... 

The historical sketch outlines the class of lanthanide amides this article is to deal with and which is further manifested in Scheme 1. Organometallic amides which can be classified as dialkyl (-aryl, -silyl) amides and amides derived from unsaturated heterocyclic ligands are seen with respect to N-unsubstituted (primary, inorganic) amides. The consideration of more classic coordination compounds like acid amides or sulfonamides, often ascribed as wet chemistry , is excluded. The historical data also demonstrate the relatively late start of lanthanide amide chemistry reflecting the late industrial establishment of the lanthanide elements (separation, purification, etc.) [9], However, lanthanide amides are still the youngest class in conjunction with the most important pillars of organometallic lanthanide chemistry, namely the alkyls/cyclopentadienyls (LnCp3, 1954, [10]) and the alkoxides (Ce(OR)4 1956 [11a] La(OR)3 , 1958 [lib]). Indeed most of the work has been conducted in the last ten years. 

C5Me5)Ln[(/i.-OCH2f-Bu)(/i.-Me)AlMe2]2 (Ln = Y, Lu) [142] were obtained from the reactions of cyclopentadienyl-substituted derivatives. According to Scheme 27, the addition of stoichiometric amounts of trimethylaluminum (n(Ln) n(Al) = 1 2) to the dimeric half-lanthanidocene bis(alkoxide) complexes quantitatively gave bis(TMA) adducts. 

Three classes of hybrid HPA are known to be stable to hydrolysis 1. Organometallic derivatives of the type RM (M = Si, Ge, Sn, Pb and R = alkyl or aryl). 2. Cyclopentadienyl-titaninm derivatives. 3. Zirconium alkoxide or phosphate derivatives, all of which are illustrated in Figure 2. We have tested phenyl model compounds of all of these for stability by boiling them in 6M HCl or H2O2 solution. This study showed that only PhP-O-HPA moieties are stable under conditions likely to be encountered in a fuel cell. Never the less we continue to study model compounds of the type RSi-O-HPA due to the large diversity of available ethoxy- and chloro- silanes. 

The reactivity of such compounds has been studied in detail 201-212). Substitution of the 7r-cyclopentadienyl group has been investigated for monocyclopentadienyl halogen and alkoxytitanium derivatives, dicyclo-pentadienyltitanium halides and alkoxides 201-211), and for (77-a llyl) (77-cyclopentadienyl)palladium 212a). The stereochemistry of these complexes has been confirmed unequivocally by physical methods including X-ray studies. The structures of (77-allyl)(7T-cyclopentadienyl)palladium 213) and of (77-cyclopentadienyl)titanium trichloride 214) are shown. 

The complexes [ N[CH2CH2NSiMc3]3 AnCl]2 (An = Th, U) were first reported the molecular structure of the uranium complex demonstrated it was dimeric in the solid state. The chloride ligand may be substituted, and derivatives incorporating cyclopentadienyl, borohydride, alkoxide, amide, and diazabutadiene derivatives have been characterized. Attempts to alkylate the... 

The formation of anionic rare earth metal ligand moieties or ate complexation are commonly observed features of salt metathesis reactions when alkali metal cyclopentadienyl [147], alkyl [96], amide [97,255] and alkoxide derivatives are employed [Eqs. (39)-(42)] [256]. 

The first well-characterized cyclopentadienyl complexes of tetravalent cerium were the alkoxide derivatives Cp3Ce(OR) (R= Pr, Bu) and Cp2Ce(0 Bu)2. The first compound of this type, Cp3Ce(OTr), was obtained in minute quantities (4% yield) upon treatment of cerimn(IV) tetraiso-propoxide with magnesocene according to Scheme 21. The new complex Cp3Ce(OTr) could be isolated by sublimation from the reaction mixture in the form of black microcrystals. ... 

X-ray powder diffraction data reveal that CP3UCI and Cp3ThCl are isomor-phous. Tris(cyclopentadienyl)thorium derivatives of other halides, alkoxides, tetrahydroborates, etc., can be prepared in a manner analogous to the uranium reaction above [58]. Tris(cyclopentadienyl)neptunium chloride, Cp3NpCl, can be prepared either by a radiochemical synthesis [75] ... 

The compounds (r/-CsHs)3UCl and (r/-CsHs)3ThCl are useful precursors for the synthesis of a large number of organoactinides, such as tris(cyclopentadienyl)metal alkoxides, tetrahydroborates, alkyls and aryls, halides, amides, and other derivatives,The chlorouranium compound was first synthesized by Reynolds and Wilkinson in 1956 from uranium tetrachloride and sodium cyclopentadienide in tetrahydrofuran. Vacuum sublimation, in our hands, invariably gives the pure product in low yield. The thorium analog was originally prepared in a similar manner,... 

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