Preparation, X-ray Crystallographic Analysis, and Stereoselective Electrophilic Capture of Coordinatively Isomeric exo-Lithium Complexes of Isodicyclopentadiene

Zaegel, Florence; Gallucci, Judith C.; Meunier, Philippe; Gautheron, B.; Sivik, Mark R.; Paquette, Leo A.

doi:10.1021/ja00093a070

Cited by 62 publications

(26 citation statements)

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“…As seen in an earlier model for (4) (Zaegel et al, 1994), the large anisotropic displacement parameters for the TMEDA ligand, in particular for C11 and C12,o along with a short Cll----C12 bond length of 1.312(10)A, indicate a disorder problem for this group with respect to the orientation of the ethylene bridge. This bridge was modeled here (SHELXL93; Sheldrick, 1993) with two sets of atoms: C I 1A--C12A and CllB--C12B, with occupancy factors of 0.40(2) and 0.60(2), respectively.…”

Section: Compound (4)supporting

confidence: 54%

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Two Derivatives of Lithium Isodicyclopentadienide: [(1,2,3,3a,7a-η)-4,5,6,7-Tetrahydro-4,7-methanoindenido](N,N,N',N'-tetramethylethylenediamine)lithium and Bis(1,4,7,10-tetraoxacyclododecane)lithium(1+) Bis[(1,2,3,3a,7a-η)-4,5,6,7-tetrahydro-4,7-methanoindenido]lithate(1–)

Gallucci

Sivik²,

Paquette³

et al. 1996

Acta Crystallogr C

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Selective crystallization of a solution of lithium isodicyclopentadienide, (isodiCp)Li, in dry thf or diethyl ether under argon has produced two lithium complexes: (isodiCp)Li(TMEDA), [Li(C10H11)(C6H16N2)], (4), and [Li(12-crown-4)2]+. [Li(isodiCp)2]-, [Li(C8H16O4)2]-[Li(C10H11)2], (5). In (4) the Li+ ion is coordinated to the two N atoms of the disordered TMEDA and is eta 5-coordinated to the Cp ring of the isodiCp ligand. The Li-(Cp ring centroid) distance is 1.906 (7) A. In (5) there are two independent half-molecules of the anion and one molecule of the cation in the asymmetric unit. In each anion, the Li+ ion occupies a crystallographic inversion center and is eta 5-coordinated to the two Cp rings of two isodiCp ligands. The Cp rings are in a staggered arrangement, as required by the inversion center. The Li-(Cp ring centroid) distances for the two anions are 1.987 (3) and 2.008 (3) A. In the cation of (5), the Li+ ion is coordinated to two 12-crown-4 ligands, one of which is disordered. Both (4) and (5) exhibit exo coordination of the Li+ ion to the isodiCp ligand, with a resultant slight endo bending of this ligand.

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Section: Compound (4)supporting

confidence: 54%

“…[Li(THF)4] + Recently, success has been realised in obtaining derivatives of (2) and (3) as crystalline compounds (Zaegel et al, 1994). As a result, the earlier conclusions concerning their reaction stereochemistry have been accorded additional support.…”

Section: ~~F> Lmentioning

confidence: 97%

Two Derivatives of Lithium Isodicyclopentadienide: [(1,2,3,3a,7a-η)-4,5,6,7-Tetrahydro-4,7-methanoindenido](N,N,N',N'-tetramethylethylenediamine)lithium and Bis(1,4,7,10-tetraoxacyclododecane)lithium(1+) Bis[(1,2,3,3a,7a-η)-4,5,6,7-tetrahydro-4,7-methanoindenido]lithate(1–)

Gallucci

Sivik²,

Paquette³

et al. 1996

Acta Crystallogr C

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“…. , n= 3-7) constitute one of the most amply studied domain of organometallic chemistry [21], their main group element analogues are represented by rare examples of the η 5 -cyclopentadienyl sandwiches (n = 5) of the alkaline (M = Li, Na) [22][23][24] and alkaline-earth metals (Mg, Ca, Ba) [24,25]. In contrast with transition metals, the bonding schemes of main group elements are confined to the use of their valence s-and p-orbitals, which limit the number of bonding MOs, formed in main group element sandwich compounds 4 by π -and π * -MOs of the basal rings and the valence orbitals of M, to four and, hence, the number of the "interstitial" electrons in a stable main group element sandwich structure to eight.…”

Section: Introductionmentioning

confidence: 99%

“…The experimentally observed main group element sandwiches are stabilized as the solvated and ate-type complexes with the environment of solvent molecules and counterions, which provide for delocalization of the electric charge at the central ion [21][22][23][24]. In order to fully or partially neutralize the excessive negative charge in the anions 5, they may be surrounded by the appropriate number of counterions, e.g., Li + .…”

Section: Introductionmentioning

confidence: 99%

Sandwich compounds with central hypercoordinate carbon, nitrogen, and oxygen: A quantum‐chemical study

Minyaev

Gribanova

Starikov

2006

Heteroatom Chemistry

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“…The electronic factors responsible for stability of the sandwich compounds of main group elements have been studied in detail; they are summarized in the form of the "electron octet" rule 4,5 substantiated by the discovery of various sandwich com pounds of alkali 6 and alkali earth 7,8 metals and some of the third to sixth row elements (Si, Ge, Sn, Pb, P, As, Bi, etc.). 8,9 At the same time there are only a few ex amples of stable sandwich derivatives of second row ele ments available at the moment.…”

mentioning

confidence: 99%

Sandwich compounds of second-row elements: A quantum chemical study

Gribanova

Minyaev

2006

Russ Chem Bull

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The structures and stabilities of a number of neutral and charged sandwich type boron, carbon, and nitrogen compounds designed based on the cyclophane cage and obeying the "electron octet" rule were studied by the B3LYP/6 311+G** density functional method. The possibility of targeted modification of the electronic structures of such compounds by varying the basal or bridging atomic groups was investigated. Key words: hypercoordinate boron, hypercoordinate carbon, hypercoordinate nitrogen, sandwich systems, quantum chemical calculations.Search for and studies of compounds containing hypercoordinate main group element atoms belong to the most intensively developing avenues of theoretical and experimental research. 1-3 An important problem in this field consists in elucidation of methods for targeted de sign of novel structural types of molecular systems that allow formation and stabilization of hypercoordinate cen ters. 1 In this connection, sandwich systems seem to be very attractive because their architectures allow the na ture and coordination number of the hypercoordinate cen ters to be varied over a rather wide range. The electronic factors responsible for stability of the sandwich compounds of main group elements have been studied in detail; they are summarized in the form of the "electron octet" rule 4,5 substantiated by the discovery of various sandwich com pounds of alkali 6 and alkali earth 7,8 metals and some of the third to sixth row elements (Si, Ge, Sn, Pb, P, As, Bi, etc.). 8,9 At the same time there are only a few ex amples of stable sandwich derivatives of second row ele ments available at the moment.For the simplest carbocenes 1 (X = C) the "electron octet" rule implies the formation of systems bearing rather large positive charges (m = 2 for 1, n = 3 and m = 4 for 1, n = 4); stabilization of such spe cies is precluded by electrostatic factors. 10 Additional stability can be achieved by replacing the car bon centers X by electropositive groups that favor stabilization of nonclassical configurations of the carbon atom. 3,4 For instance, B3LYP/6 311++G** calcula tions predicted that silicon containing analog of carbo cene 1 (X = Si, n = 3, m = 2) should be a stable com pound. 11 At the same time this method of solving the stabilization problem of sandwich carbon containing de rivatives is still of limited use, being confirmed by a single successful example as yet. A much more efficient is the approach based on the replacement of the carbon centers in carbocenes by boron atoms (X = B) and additional stabilization of anionic systems thus formed by lithium counterions or bridging hydrogen atoms. 10,12According to MP2 and DFT calculations with the 6 311+G* basis set, the initially unstable anionic system 2 can be stabilized on going to neutral systems 3 or 4 that contain counterions. 10,12 This approach is fruitful, 12 be ing at present a unique efficient strategy of targeted design of sandwich derivatives of the second row elements.In this work we propose a novel method for design of hydrocarbon and he...

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Preparation, X-ray Crystallographic Analysis, and Stereoselective Electrophilic Capture of Coordinatively Isomeric exo-Lithium Complexes of Isodicyclopentadiene

Abstract: The structures of organolithium compounds in solution have been the subject of attention for four decades because of concerns regarding the mode of solvation, dynamic behavior, and reactivity of ion pairs. Chiefly as a consequence of their synthetic

Cited by 62 publications

References 0 publications

Two Derivatives of Lithium Isodicyclopentadienide: [(1,2,3,3a,7a-η)-4,5,6,7-Tetrahydro-4,7-methanoindenido](N,N,N',N'-tetramethylethylenediamine)lithium and Bis(1,4,7,10-tetraoxacyclododecane)lithium(1+) Bis[(1,2,3,3a,7a-η)-4,5,6,7-tetrahydro-4,7-methanoindenido]lithate(1–)

Two Derivatives of Lithium Isodicyclopentadienide: [(1,2,3,3a,7a-η)-4,5,6,7-Tetrahydro-4,7-methanoindenido](N,N,N',N'-tetramethylethylenediamine)lithium and Bis(1,4,7,10-tetraoxacyclododecane)lithium(1+) Bis[(1,2,3,3a,7a-η)-4,5,6,7-tetrahydro-4,7-methanoindenido]lithate(1–)

Sandwich compounds with central hypercoordinate carbon, nitrogen, and oxygen: A quantum‐chemical study

Sandwich compounds of second-row elements: A quantum chemical study

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