Cyclooctatetraenyl complexes

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... 

Organometallic complexes such as tris, bis and monocylopentadienyl complexes, cyclooctatetraenyl complexes, cyclopentadienyl-cyclooctatetraenyl complexes, indenyl complexes, fluorenyl complexes, complexes with other aromatic ligands, callixerene complexes, NMR spectroscopy of organometallic complexes, vibrational spectra, and catalytic applications form the theme of the sixth chapter. 

A large number of substituted (cyclooctatetraenyl) complexes have also been reported. The addition of substituents has been employed to improve solubihty, alter electronic properties, or investigate the dynamics of ring rotation. The largest class are the 1, T-disubstituted derivatives (equation 29). ... 

Eqs. (24) and (25) are identical to those made by solution means (77). The trivalent cyclooctatetraenyl complexes, Ln2(CgHg)3, contain Ln(CgHg)2 anions identical to species made from LnCl3 and K2CgHg in solution, but the countercation is the new species, CgHgLn(thf)2. These form a tight ion pair as shown in Scheme 7. 

The investigation of actinide cyclooctatetraenyl complexes continued to be an area of active research in recent years. Especially notable among the more recent developments is the synthesis and derivative chemistry of various cationic mono(cyclooctatetraenyl) uranium(iv) and (v) complexes.71,97 The chemistry of mono(cyclooctatetraenyl)uranium complexes has been reviewed by Ephritikhine et al.lso A highly interesting essay on the discovery and chemistry of uranocene has been published by Seyferth under the title Uranocene. The First Member of a New Class of Organometallic Derivatives of the/Elements. 151... 

Cendrowski-Guillaume et al. reported the synthesis of a mixed cyclopen-tadienyl/cyclooctatetraenyl complex [U(COT)(Cp )(HMPA)] (where COT = q-CsHs, HMPA = OP(NMe2)3) [150] by the treatment of [U(COT)(HMPA)3] [BPh4] with KCp. The complex [U(COT)(Cp )(HMPA)] was characterized crystallographically and was found to adopt trigonal configuration as shown... 

Cyclooctatetraenyl complexes of the rare earths in the oxidation state R ... 

The Ln oxidation state in organometallic compounds is known only for cerium. It should be noted, however, that in some cases offered pathways to Ce complexes are apparently wrong and give in reality compounds with Ce. Only alkoxides (RO)4Ce, CpjCeOR and cyclooctatetraenyl complex (CgH8)2Ce are well-defined compounds of Ce. ... 

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.). 

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