Silylation cyclopentadienyl derivatives

Organoactinide chemistry initially developed around the use of the ubiquitous cyclopentadienyl ligand (see Cyclopentadienyl), Cp = C5H5, and subsequently its alkyl- and silyl-substituted derivatives. The tetravalent oxidation state... 

Treatment of Cp"Cr(Ti -Cot), Cp" = Cp, Cp with (EtCN)3M(CO)3, M = Mo, W and Fe2(CO)9 affords the complexes [(Cp Cr)(CO)3M][ i-Cot], M = Fe, Cr, W, Cp = Cp and I(Cp Cr)(CO)3Crl/i-Cot, Cot = Cyclooctatetrane, which have been spectroscopically characterised. Bimetallic complexes containing bis(tetramethylcyclopentadienyl) dimethylsilane bridges have been prepared from the reaction of arene tricarbonyl molybdenum complexes with the silyl substituted cyclopentadienyl derivative. The synthesis of pinanylcyclopentadienes followed by metallation and reaction with Mo(CO)s and Mel gives the chiral (-)-[(ii -C5Me4-3-pinanyl)(CO)3Me], which has been structurally characterised. The chiral methallyl complexes CpMo(NO)X(Ti -2-methallyl) X = camphorsulfonate have been resolved and the reactions of the... 

One of the standard procedures for the synthesis of half-sandwich cyclopen-tadienyltitanium trichlorides involves the use of silylated cyclopentadienyl [44] derivatives in cases where the use of lithiated compounds leads to reduction of the metal center [22],... 

Simple cyclobutanes do not readily undergo such reactions, but cyclobutenes do. Ben-zocyclobutene derivatives tend to open to give extremely reactive dienes, namely ortho-c]uin(xlimethanes (examples of syntheses see on p. 280, 281, and 297). Benzocyclobutenes and related compounds are obtained by high-temperature elimination reactions of bicyclic benzene derivatives such as 3-isochromanone (C.W. Spangler, 1973, 1976, 1977), or more conveniently in the laboratory, by Diels-Alder reactions (R.P. Thummel, 1974) or by cycliza-tions of silylated acetylenes with 1,5-hexadiynes in the presence of (cyclopentadienyl)dicarbo-nylcobalt (W.G, Aalbersberg, 1975 R.P. Thummel, 1980). 

Cyclopentadienyl rhodium silyl derivatives include Cp Rh(H)2(SiEt3)2, which has been used as a precursor to heterometallic clusters.257 The photolysis of CpRh(PPh3)(7]2-C2H4) with SiHR3 (R = Et, Pr1) results in oxidative... 

Organosilyl substituted 7)5-cyclopentadienyl complexes may be prepared by two main procedures (a) reactions of silylated cyclopenta-dienes or their alkali metal derivatives, with an appropriate transition metal compound (carbonyl or halide) with formation of ir-bonds (b) metalation of a preformed 7j5-cyclopentadienyl complex, followed by treatment with an organohalosilane. 

Triphenylsilyl zirconium and hafnium derivatives have been prepared from the silyl lithium species. Triphenylsilyl bis(cyclopentadienyl) zirconium chloride undergoes carbonyl insertion under pressure of carbon monoxide (100 psi) to give the corresponding acyl zirconium species which, upon treatment with anhydrous hydrogen chloride in a benzene matrix at —196 °C and warming to room temperature, gives rise to formyl triphenylsilane55. 

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. 

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