Metallorganische verbindungen der lanthanoide XCVI. Ylidartige olefinkoordination in komplexen dreiwertiger 4f-elemente

Schumann, Herbert; Glanz, Mario; Winterfeld, Jörn; Hemling, Holger; Kühn, Norbert; Bohnen, Hans; Bläser, Dieter; Boese, Roland

doi:10.1016/0022-328x(95)05435-r

Cited by 59 publications

(22 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…[7] For comparison, the Nd-C bond lengths in four-coordinate (L)Nd[N(SiMe 3 ) 2 ] 2 (L = amido-linked nhc) [20] and Nd[N(SiMe 3 ) 2 ] 3 (LЈ) (LЈ = 1,3,4,5-tetramethyl-2-methyleneimidazoline) are 2.609(3) and 2.691(6) Å, respectively. [21] The carbene ligands in Ln[N(SiHMe 2 ) 2 ] 3 (nhc) 2 are slightly tilted and are arranged in a way that their mean square planes are almost perpendicular [87.6 (Y), 89.3°(Nd)]. [21] The peculiar bonding fea- [22] Noteworthy is also the distinct bonding of the Si-N-Si fragments which are twisted out of the N1N2N3 plane by 32.5, 41.0, and 28.2°.…”

Section: Synthesis and Characterization Of Complexes With Neutral Donmentioning

confidence: 97%

“…[21] The carbene ligands in Ln[N(SiHMe 2 ) 2 ] 3 (nhc) 2 are slightly tilted and are arranged in a way that their mean square planes are almost perpendicular [87.6 (Y), 89.3°(Nd)]. [21] The peculiar bonding fea- [22] Noteworthy is also the distinct bonding of the Si-N-Si fragments which are twisted out of the N1N2N3 plane by 32.5, 41.0, and 28.2°. This is in contrast to 2b where due to the molecules C3 symmetry all three amido ligands are arranged in the same fashion (27°) and to 1b exhibiting one large torsion angle (57.4°) and two smaller ones (7.6°and 16.4°).…”

Section: Synthesis and Characterization Of Complexes With Neutral Donmentioning

confidence: 97%

See 1 more Smart Citation

Donor and ate‐Coordination in Rare‐Earth Metal Bis(dimethylsilyl)amide Complexes

et al. 2008

View full text Add to dashboard Cite

Section: Synthesis and Characterization Of Complexes With Neutral Donmentioning

confidence: 97%

Section: Synthesis and Characterization Of Complexes With Neutral Donmentioning

confidence: 97%

Donor and ate‐Coordination in Rare‐Earth Metal Bis(dimethylsilyl)amide Complexes

et al. 2008

View full text Add to dashboard Cite

“…[10] We postulated that an adduct similar to [Nd(N'') 3 {H 2 C=C-(NMeCMe) 2 }] could form, [11] which in one resonance form can be represented as aNHC-protected methylidene,but also that as well as being nucleophilic the methylene groups of NHOs are basic by virtue of the dipolar resonance form H 2 C À -C + (NRCH) 2 . [12] Given the existence of MICs,w e considered whether 2 could be converted by transfer of an olefinic hydrogen atom to the methylene group in af ormal 1,4-proton shift to give its MIC form with concomitant metal stabilization.…”

mentioning

confidence: 99%

Rare‐Earth‐ and Uranium‐Mesoionic Carbenes: A New Class of f‐Block Carbene Complex Derived from an N‐Heterocyclic Olefin

et al. 2017

View full text Add to dashboard Cite

Neutral mesoionic carbenes (MICs) have emerged as an important class of carbene,however they are found in the free form or ligated to only afew d-block ions.Unprecedented f-block MIC complexes [M(N'') 3 {CN(Me)C(Me)N(Me)CH}] (M = U, Y, La, Nd;N '' = N(SiMe 3 ) 2 )a re reported. These complexes were prepared by af ormal 1,4-proton migration reaction when the metal triamides [M(N'') 3 ]w ere treated with the N-heterocyclic olefin H 2 C=C(NMeCH) 2 ,which constitutes an ew,g eneral wayt op repare MIC complexes.Q uantum chemical calculations on the 5f 3 uranium(III) complex suggest the presence of aU =Cd onor-acceptor bond, composed of aM IC!U s-component and aU (5f)!MIC(2p) p-backbond, but for the d 0 f 0 Ya nd La and 4f 3 Nd congeners only MIC!M s-bonding is found. Considering the generally negligible p-acidity of MICs,t his is surprising and highlights that greater consideration should possibly be given to recognizing MICs as potential p-acid ligands when coordinated to strongly reducing metals.Over the past three decades the field of stable singlet Nheterocyclic carbenes (NHCs, I,S cheme 1) has become ab urgeoning area.[1] Within that time,avariety of experimentally viable classes of carbenes related to I have emerged, including anionic-NHCs (II), [2] cyclic alkylaminocarbenes (CAAC, III), [3] and various charge-neutral mesoionic carbenes (MIC, IV-VI), [4] Scheme 1, where for the latter no reasonable canonical resonance forms can be drawn without assigning additional formal charges.Agrowing number of MICs of type IV are known, but it is notable that all examples to date pertain to either the free carbene,o rw ere formed at and remain coordinated to surprisingly few transition metal ions, [4] which contrasts to NHCs that have been coordinated to the majority of metals in the periodic table.[1] Where the bonding of these MICs to metals is concerned, complexes are usually considered to have strong MIC!metal s-donation. Given that strong s-donation, it is surprising that MIC complexes are limited to even only af ew transition metals, but this may reflect the limited range of methodologies to deliberately prepare metal-MIC complexes.Interestingly,any p-bonding components of metal-MIC bonds are,u nlike NHCs,r arely explicitly considered.[5] This is likely because MICs are anticipated to have at best weak p-acceptor character since the carbene is strongly stabilized by N-lone pair and vinyl groups,a se videnced by computational comparisons of different classes of carbenes. [6] We report herein the synthesis and characterization of rare-earth-MIC and uranium-MIC complexes,which are the first f-block-MIC complexes so by definition anew class of fblock-carbene complex. [7] Thec omplexes reported herein were prepared by the formal 1,4-proton migration of an Nheterocyclic olefin (NHO) that represents an ew,g eneral method by which to prepare MIC complexes.I nterestingly, quantum chemical calculations suggest that the 5f 3 uranium-(III) ion engages in aweak p-back-bond to the MIC utilizing a5felectron, whereas the ...

show abstract

“…For example, lanthanoids in the oxidation state + 3 form trianionic hexamethyl complexes. [8] The first organolanthanoid compound with a direct bond between the lanthanoid and a third-row element, [9] a series of organolanthanoid hydrides, [10] and the first NHC [11] and olefin complexes [12] of the lanthanoids were synthesized in Schumanns research group. Further studies, some of which were in collaboration with partners in industry, involved alkalineearth metallocenes, lanthanoid-containing contrast agents for magnetic resonance imaging, and catalytically active transition-metal complexes with phosphane, stibane, and bismutane ligands for the hydrogenation and isomerization of olefins.…”

mentioning

confidence: 99%

Herbert Schumann (1935–2010)

Hahn

2010

Angew Chem Int Ed

View full text Add to dashboard Cite

Metallorganische verbindungen der lanthanoide XCVI. Ylidartige olefinkoordination in komplexen dreiwertiger 4f-elemente

Cited by 59 publications

References 33 publications

Donor and ate‐Coordination in Rare‐Earth Metal Bis(dimethylsilyl)amide Complexes

Donor and ate‐Coordination in Rare‐Earth Metal Bis(dimethylsilyl)amide Complexes

Rare‐Earth‐ and Uranium‐Mesoionic Carbenes: A New Class of f‐Block Carbene Complex Derived from an N‐Heterocyclic Olefin

Herbert Schumann (1935–2010)

Contact Info

Product

Resources

About