Cyclooctatetraenyl complexes preparation

Cyclooctatetraenyl complexes in which the metal is attached to the organic ring framework via a a bond to carbon are rare. The racemic iron compound 104 has been prepared, and its diastereoisomeric phosphine derivatives 105 (only one diastereoisomer shown) have been synthesized by photochemical replacement of a CO ligand in 104 by PR3 (180). Compound 104 exists as two... 

The interaction of alkyl(aryl)lithium with chlorides (CgHg)LnCl allows to prepare cyclooctatetraenyl complexes with a-bonded substituents of the (CgH8)LnR type [45, 46] (see Section I.3.). 

Ethynylruthenocene acetylides, preparation, 6, 642 ETL, see Electron-transporting layer ET reactions, see Electron-transfer reactions Europium complexes with arenes, 4, 118-119 Cp2Ln compounds, 4, 27 CpLnX2 compounds, 4, 29-30 Cp2M compounds, 4, 63 cyclooctatetraenyl compounds, 4, 122-123 heterobimetallic compounds without direct M—M bonds,... 

Mono(cyclooctatetraenyl) lanthanide(III) compounds, synthesis and characteristics, 4, 124 Mono(cyclooctatetraenyl) zirconium(III) compounds, preparation and reactions, 4, 743 Mono(cyclopentadienyl) amido complexes alkane elimination, 4, 446 amine elimination, 4, 442 HCL elimination, 4, 446 metathesis reactions, 4, 438 miscellaneous reactions, 4, 448 properties, 4, 437... 

A recent development in this field involves the combination of benzamidi-nate ligands with cyclopentadienyl or cyclooctatetraenyl ligands in the coordination sphere of lanthanide ions. The first lanthanide complexes containing both benzamidinate and pentamethylcyclopentadienyl bonded to yttrium was reported by Teuben et al. Yttrium aryloxides as well as anhydrous yttrium trichloride can be used as starting materials in these preparations (Eq. 19, Scheme 5) [27] ... 

More recently several lanthanide diiminophosphinate derivatives containing additional i/8-cyclooctatetraenyl ligands have been prepared and characterized. The complexes [Ph2P(NSiMe3)2](C8H8)Ln(THF) (58) were obtained according to Eq. (22) and isolated as air-sensitive, crystalline solids in 77-84% yield [71] ... 

Cyclooctatetraenyl lanthanide(III) halides of the type [(COT)Ln(/x-Cl)(THF)2]2 (Figure 77a) are the most important precursors for the preparation of other half-sandwich (see Half-sandwich Complexes) and mixed sandwich complexes with cyclooctatetraenyl ligands. These complexes are readily accessible by reacting anhydrons lanthanide trichlorides with K2[C0T] in a molar ratio of 1 1. The compounds consist of centrosyimnetric, chloro-bridged dimers with... 

Following the synthesis of tris(cyclopentadienyl) lanthanide complexes, the first examples of organolanthanide derivatives, a vast number of organolanthanide it-complexes with cyclopen-tadienyl (Cp), indenyl (Ind), cyclooctatetraenyl (COT), and related substituted derivatives have been prepared and extensively reviewed [3]. Here we will briefly discuss cyclopentadienyl and allyl derivatives as representatives of organolanthanide K-complexes. 

The dimeric mono(cyclooctatetraenyl)lanthanide chlorides [(COT)Ln(/r-Cl)(THF)2]2 are long known and still represent the most useful precursors in (COT)Ln chemistry. A recently reported alternative preparation of the Sm derivative involves the reaction of samarium metal with COT in THF in the presence of a small amount of I IgCL. The molecular structure of [(COT)Sm(/i-CI)(TT 11 )2]2 has been determined.805,806 Iodo-(cyclooctatetraenyl)lanthanide iodides of the type (COT)Lnl(TIIF) (Ln = La, Ce, Pr, n = 3 Ln = Nd, n = 2 Ln = Sm, n l) are readily accessible in a one-pot reaction of metallic lanthanides with COT in the presence of an equimolar amount of iodine. Bromo- and chloro-bridged binuclear complexes of samarium, [(COT)Sm(/.t-X)(THF )2]2 (X = Br, Cl), were also prepared by the reaction of samarium metal with COT in the presence of 1,2-dibromoethane or Ph3PCl2, respectively.807 Alternatively, the iodo complexes (COT)LnI(THF)3 (Ln = Nd, Sm) can be synthesized directly from the lanthanide triiodides and K2COT. The molecular structure of (COT)Ndl(THF)3 has been determined by X-ray diffraction.808 A clean preparation of the monomeric half-sandwich complex (GOT)TmI(THF)2 involves treatment of Tml2 with equimolar amounts of COT in THF at room temperature (Scheme 227). The product was isolated as red crystals in 75% yield.628... 

Although the elements of the lanthanide and actinide series have long been known to exhibit a quite extensive organometallic chemistry, it is only within the last decade that typical sandwich species have been prepared and studied. These systems however, although resembling the familiar metallocene and bis-arene compounds of the d-block elements, are not strictly their analogues since in both f-orbital series the known sandwich complexes are derived only from the cyclooctatetraenyl dianion. 

The first actinide organometallic complex, red-brown (C5H5)3UC1, was prepared and characterized by Reynolds and Wilkinson in 1956 or shortly after the discovery of ferrocene see Ferrocene, (C5H5)2pe. However, it was not until the preparation and structural characterization of bis(cyclooctatetraenyl)uranium, (C8H8)2U ( uranocene , see Uranocene) in 1968 and the isolation and characterization of uranium alkyls see Alkyl Complexes) in 1973 that the field developed momentum. The purpose of this chapter is to provide an overview of organoactinide chemistry that reflects historical as well as recent developments and achievements in the field it is not meant to be an exhaustive review of the primary literature. More detailed discussion, background material, and extensive references to the literature can be found in several excellent reviews. 

Cyclooctatetraenyl derivatives of the rare earths were synthesized shortly after the characterization of uranocene first for europium and ytterbium in the oxidation state R by Hayes and Thomas (1969a). But one year later, Mares et al. (1970) prepared complexes of the type K[R(Cj,Hg)2], where R = Ce, Pr, Nd, Sm, and Tb. The corresponding yttrium, lanthanum and gadolinium derivatives are described by Hodgson et al. (1973) and the scandium compound was made by Westerhof and De Liefde Meijer in 1976 ... 

Mixed sandwich complexes of the rare earths containing cyclopentadienyl and cyclooctatetraenyl ligands were prepared either by the reaction of cyclopentadienyl rare earth dichlorides with dipotassium cyclooctatetraenide or form cyclooctatetraenyl rare earth chlorides and sodium cyclopentadienide in tetrahydrofuran (Jamerson et al., 1974) ... 

The di(cyclooctatetraenyl) cerium complex was prepared by the reaction of cerium tetra-iso-propoxide with triethyl aluminum in cyclooctatetraene at 140°C (Greco et al., 1976) ... 

In 1970, tne first cyclooctatetraenyl compounds of the lanthanoides in the trivalent oxidation state were prepared (lOii). The reactions of LnCla with KaCsHe in THF afford the following complexes, which are stable up to about 160°C, but sensitive towards air and moisture (10U,105,... 

---