Organolanthanides and organoactinides. XV. Synthesis and properties of new .sigma.-bonded organolanthanide complexes

Abstract

A series of new organolanthanide complexes containing bonds has been synthesized. The complexes are of the type (pS-CsHshLnR (R = methyl, phenyl, and phenylacetylide) and are synthesized by the reaction of the appropriate RLi compound with (??5-C5H5)2LnCl complexes. The new complexes have been characterized by vibrational and visible spectroscopy, as well as by magnetic susceptibility. The infrared data support the presence of ligands which are bonded to the metal.The magnetic data and, to a lesser extent, the visible data indicate that there is enhanced covalency in the lanthanide-carbon bond. The nature of this covalency and possible f-orbital involvement in the bonding are discussed.Beginning with the preparation of uranocene in 1968 and the subsequent claim that the f orbitals were involved in the bonding,3 there has been a dramatic resurgence of interest in the organometallic chemistry of the lanthanides and actinides. However, until the last three years, most of the work has been concerned with complexes which contained only -bonded ligands.4™10 Although -bonded organometallic compounds are well documented for the d-block transition metals,11 they have been relatively unknown for the lanthanides and actinides. Consequently, much of the significant recent progress in the

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A Rare-Earth Metal Retrospective to Stimulate All Fields

“…The suggestion that organometallic complexes of the larger early lanthanides could not be prepared was reiterated in 1975 in a paper by Tsutsui on “(C 5 H 5 ) 2 LnMe” and “(C 5 H 5 ) 2 LnPh” complexes of Ln = Gd, Er, and Yb, and “(C 5 H 5 ) 2 Ln­(CCPh)” complexes of Ln = Gd, Ho, Er, and Yb, eq The authors wrote:It has been suggested that the size of the lanthanides influenced the success or failure of a particular reaction.…”

Reaction of (C5Me5)2Yb(ER)(NH3) with Me3Al. Formation of (C5Me5)2Yb(AlMe4) and [(C5Me5)2Yb(ER)(AlMe3)2]2

“…This complexity is not apparent from the synthesis of the simplest methyl derivative, (C 5 H 5 ) 2 YbMe, which was described 28 years ago. 1 In this synthesis (C 5 H 5 ) 2 YbCl, which is a chloride-bridged dimer in the solid state, is allowed to react with methyllithium in a mixture of tetrahydrofuran-diethyl ether solvent. 2 The orange (C 5 H 5 ) 2 YbMe is sparingly soluble in aromatic hydrocarbons but the degree of association in solution was not determined.…”