Chemistry of Tris(pentamethylcyclopentadienyl) f-Element Complexes, (C5Me5)3M

Evans, William J.; Davis, Benjamin L.

doi:10.1021/cr010298r

Cited by 314 publications

(233 citation statements)

References 148 publications

(400 reference statements)

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“…Recent developments in the organometallic chemistry of the f elements have shown that it is possible to isolate an entire series of (C 5 Me 5 ) 3 M complexes in which the M-C bond distances are longer than conventional bond lengths (2). The ligands in these so-called long-bond organometallic complexes display different patterns of reactivity because they are not in a bonding arrangement that gives them their usual amount of stabilization.…”

Section: T He Pentamethylcyclopentadienyl Ligand (C 5 Me 5 )mentioning

confidence: 99%

“…Both modes of reactivity apparently derived from the steric crowding in the molecule, and the reductive chemistry was accordingly called sterically induced reduction (SIR) (2,10). These reactions demonstrated that the reactivity of a normally inert ancillary ligand, in this case (C 5 Me 5 ) 1Ϫ , can be substantially modified by creating a coordination environment in which the ligands have unusually long bonds.…”

Section: T He Pentamethylcyclopentadienyl Ligand (C 5 Me 5 )mentioning

confidence: 99%

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C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C ₅ Me ₅ ) ₃ M complexes

Evans

Davis

Champagne

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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113

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Synthesis of the sterically crowded Tris(pentamethylcyclopentadienyl) lanthanide complexes, (C 5Me5)3Ln, has demonstrated that organometallic complexes with unconventionally long metal ligand bond lengths can be isolated that provide options to develop new types of ligand reactivity based on steric crowding. Previously, the (C 5Me5)3M complexes were known only with the larger lanthanides, La-Sm. The synthesis of even more crowded complexes of the smaller metals Gd and Y is reported here. These complexes allow an evaluation of the size͞reactivity correlations previously limited to the larger metals and demonstrate a previously undescribed type of C 5Me5-based reaction, namely C-H bond activation. (C 5Me5)3Gd, was prepared from GdCl3 through (C 5Me5)2GdCl2K(THF)2, (C5Me5)2Gd(C3H5), and [(C5Me5)2Gd][BPh4] and structurally characterized by x-ray crystallography. Although Gd 3؉ is redox-inactive, (C5Me5)3Gd functions as a reducing agent in reactions with 1,3,5,7-cyclooctatetraene (COT) and triphenylphosphine selenide to make (C 5Me5)Gd(C8H8), [(C5Me5)2Gd]2Se2, and [(C 5Me5)2Gd]2Se depending on the stoichiometry used. When the analogous synthetic method was attempted with yttrium in arene solvents, the previously characterized (C 5Me5)2YR complexes (R‫؍‬C 6H5, CH2C6H5) were isolated instead, i.e., C-H bond activation of solvent occurred. To avoid this problem, (C 5Me5)3Y was synthesized in high yield from [(C 5Me5)2YH]2 and tetramethylfulvene in aliphatic solvents. Isolated (C 5Me5)3Y was found to metalate benzene and toluene with concomitant formation of C 5Me5H, a reaction contrary to the normal pK a values of these hydrocarbons. In this case, the normally inert (C 5Me5) 1؊ ligand engages in C-H bond activation due to the extreme steric crowding.sterically induced reduction ͉ lanthanide ͉ pentamethylcyclopentadienyl ͉ arene activation ͉ long-bond organometallics

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Section: T He Pentamethylcyclopentadienyl Ligand (C 5 Me 5 )mentioning

confidence: 99%

Section: T He Pentamethylcyclopentadienyl Ligand (C 5 Me 5 )mentioning

confidence: 99%

C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C ₅ Me ₅ ) ₃ M complexes

Evans

Davis

Champagne

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

113

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“…In the f-block, lanthanide complexes of carbocyclic p-ligands constitute a mature aspect of organolanthanide chemistry [9][10][11] . In part, this is because anionic p-ligands, such as cyclopentadienyl, bind strongly to metal centres whose bonding can be principally characterized as electrostatic.…”

mentioning

confidence: 99%

Reductive assembly of cyclobutadienyl and diphosphacyclobutadienyl rings at uranium

et al. 2013

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Despite the abundance of f-block-cyclopentadienyl, arene, cycloheptatrienyl and cyclooctatetraenide complexes, cyclobutadienyl derivatives are unknown in spite of their prevalence in the d-block. Here we report that reductive [2 þ 2]-cycloaddition reactions of diphenylacetylene and (2,2-dimethylpropylidyne)phosphine with uranium(V)-inverted sandwich 10p-toluene tetra-anion complexes results in the isolation of inverted sandwich cyclobutadienyl and diphosphacyclobutadienyl dianion uranium(IV) complexes. Computational analysis suggests that the bonding is predominantly electrostatic. Although the c 4 molecular orbital in the cyclobutadienyl and diphosphacyclobutadienyl ligands exhibits the correct symmetry for d-bonding to uranium, the dominant covalent contributions arise from p-bonding involving c 2 and c 3 orbital combinations. This contrasts with uranium complexes of larger arenes and cyclo-octatetraenide, where d-bonding dominates. This suggests that the angular requirements for uranium to bond to a small four-membered ring favours p-bonding, utilizing 5f-instead of 6d-orbitals, over d-bonding that is favoured with larger ligands, where 6d-orbitals can become involved in the bonding.

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“…This is particularly important when comparing it to substituted cyclopentadienyls. From our point of view, substituted cyclopentadienyls are usually sterically demanding, which facilitates the isolation of unstable compounds but hinders their reactivity (Evans and Davis, 2002).…”

mentioning

confidence: 99%

Rare Earth Arene-Bridged Complexes Obtained by Reduction of Organometallic Precursors

Huang

Diaconescu

2014

Including Actinides

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Rare earth chemistry has witnessed remarkable advances in recent years. In particular, ancillary ligands other than cyclopentadienyl derivatives have been introduced to the organometallic chemistry and their complexes exhibit distinct reactivity and properties compared to the metallocene or half-sandwiched analogues. The present chapter reviews arene-bridged rare earth complexes with an emphasis on those compounds obtained by reduction reactions. A particular emphasis is placed on rare earth complexes supported by 1,1′-ferrocenediyl diamides since they show the most diverse chemistry with arenes: fused arenes, such as naphthalene and anthracene, formed inverse-sandwiched complexes, in which the arene is dianionic; weakly conjugated arenes, such as biphenyl, p-terphenyl, and 1,3,5-triphenylbenzene, were unexpectedly reduced by four electrons and led to 6-carbon, 10- electron aromatic systems; on the contrary, (E)-stilbene, which has a carbon-carbon double bond between the two phenyl rings, could only be reduced by two electrons, which were located on the carbon-carbon double bond instead of the phenyl rings.

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Chemistry of Tris(pentamethylcyclopentadienyl) f-Element Complexes, (C₅Me₅)₃M

Cited by 314 publications

References 148 publications

C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C ₅ Me ₅ ) ₃ M complexes

C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C ₅ Me ₅ ) ₃ M complexes

Reductive assembly of cyclobutadienyl and diphosphacyclobutadienyl rings at uranium

Rare Earth Arene-Bridged Complexes Obtained by Reduction of Organometallic Precursors

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Chemistry of Tris(pentamethylcyclopentadienyl) f-Element Complexes, (C5Me5)3M

Cited by 314 publications

References 148 publications

C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C 5 Me 5 ) 3 M complexes

C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C 5 Me 5 ) 3 M complexes

Reductive assembly of cyclobutadienyl and diphosphacyclobutadienyl rings at uranium

Rare Earth Arene-Bridged Complexes Obtained by Reduction of Organometallic Precursors

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Chemistry of Tris(pentamethylcyclopentadienyl) f-Element Complexes, (C₅Me₅)₃M

C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C ₅ Me ₅ ) ₃ M complexes

C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C ₅ Me ₅ ) ₃ M complexes