Tripodal Amido Complexes:  Molecular “Claws” in Main Group and Transition Metal Chemistry

Gade, Lutz H.

doi:10.1021/ar010116f

Cited by 145 publications

(58 citation statements)

References 46 publications

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“…The chemistry of [E 14 R 3 ] ðÀÞ anionic trisubstituted metalate(II) of group 14 elements -Ge(II), Sn(II) and Pb(II) ate-complexes -containing amido-or oxo-ligands has attracted considerable attention in recent years [1][2][3][4][5][6]. The structural features of E 14 R 3 fragment, reduced ability of the E 14 atom to the oxidation due to the presence of electronegative N-or O-substituents and increased stability R 3 E 14 -M (M ¼ transition metal) bond to the homolytic cleavage allow to employ these compounds in transition metals coordination chemistry as components of potential catalytic systems, as precursors for electronic and ceramic materials, etc.…”

Section: Introductionmentioning

confidence: 99%

Ate complexes of Ge(II) and Sn(II) with bidentate ligands [LiE14(OCH2CH2NMe2)3]2 (E14=Ge, Sn): synthesis and structure

Khrustalev

Antipin

Zemlyansky

et al. 2004

Journal of Organometallic Chemistry

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Section: Introductionmentioning

confidence: 99%

Ate complexes of Ge(II) and Sn(II) with bidentate ligands [LiE14(OCH2CH2NMe2)3]2 (E14=Ge, Sn): synthesis and structure

Khrustalev

Antipin

Zemlyansky

et al. 2004

Journal of Organometallic Chemistry

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“…Tripodal ligands are designed to bind facially to a metal centre, [12] and in this case threefold rotational symmetry represents the highly symmetrical reference system adapted to this topology of ligation, in the same way that C 2 symmetry is related to simple chelation.…”

Section: Designing Chiral Stereodirecting Ligands Based On a Tripod Tmentioning

confidence: 99%

Exploiting Threefold Symmetry in Asymmetric Catalysis: The Case of Tris(oxazolinyl)ethanes (“Trisox”)

Gade

Bellemin‐Laponnaz

2008

Chemistry A European J

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Rotational molecular symmetry, modularity and other aspects of ligand design have played a role in the development of a new class of stereodirecting ligands. The use of highly symmetrical, stereodirecting ligands may reduce the number of transition states and diastereomeric reaction intermediates and, in favourable cases, this degeneration of alternative reaction pathways may lead to high stereoselectivity in catalytic reactions and greatly simplifies the analysis of such transformations. In this concept article, we describe the way in which these considerations have played a role in the development of a new class of stereodirecting ligands. Tris(oxazolinyl)ethanes ("trisox") have proved to be versatile ligand systems for the development of enantioselective catalysts of the d- and f-block metals employed in a wide range of catalytic conversions. These include Lewis acid catalysed transesterifications, C-C and C-N coupling reactions, the catalytic polymerisation of alpha-olefins as well as Pd-catalysed allylic alkylations. An overview of the current state of this field is given and the potential for further development will be highlighted.

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“…The importance of the ligand environment in controlling the reactivity of polydentate amidedonor complexes is well known, and there are a number of closely related complexes which are useful for small molecule activation. [10,11] Therefore, the systems developed by Fryzuk and Schrock can be taken to represent two classes of sterically hindered polydentate complexes, and the insights gained from studying their reactivity can be applied in other situations.…”

Section: Introductionmentioning

confidence: 99%

Dinitrogen Activation by Fryzuk’s [Nb(P₂N₂)] Complex and Comparison with the Laplaza–Cummins [Mo{N(R)Ar}₃] and Schrock [Mo(N₃N)] Systems

Christian

Terrett

Stranger

et al. 2009

Chemistry A European J

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The reaction profile of N(2) with Fryzuk's [Nb(P(2)N(2))] (P(2)N(2)=PhP(CH(2)SiMe(2)NSiMe(2)CH(2))(2)PPh) complex is explored by density functional calculations on the model [Nb(PH(3))(2)(NH(2))(2)] system. The effects of ligand constraints, coordination number, metal and ligand donor atom on the reaction energetics are examined and compared to the analogous reactions of N(2) with the three-coordinate Laplaza-Cummins [Mo{N(R)Ar}(3)] and four-coordinate Schrock [Mo(N(3)N)] (N(3)N=[(RNCH(2)CH(2))(3)N](3-)) systems. When the model system is constrained to reflect the geometry of the P(2)N(2) macrocycle, the N--N bond cleavage step, via a N(2)-bridged dimer intermediate, is calculated to be endothermic by 345 kJ mol(-1). In comparison, formation of the single-N-bridged species is calculated to be exothermic by 119 kJ mol(-1), and consequently is the thermodynamically favoured product, in agreement with experiment. The orientation of the amide and phosphine ligands has a significant effect on the overall reaction enthalpy and also the N--N bond cleavage step. When the ligand constraints are relaxed, the overall reaction enthalpy increases by 240 kJ mol(-1), but the N(2) cleavage step remains endothermic by 35 kJ mol(-1). Changing the phosphine ligands to amine donors has a dramatic effect, increasing the overall reaction exothermicity by 190 kJ mol(-1) and that of the N--N bond cleavage step by 85 kJ mol(-1), making it a favourable process. Replacing Nb(II) with Mo(III) has the opposite effect, resulting in a reduction in the overall reaction exothermicity by over 160 kJ mol(-1). The reaction profile for the model [Nb(P(2)N(2))] system is compared to those calculated for the model Laplaza and Cummins [Mo{N(R)Ar}(3)] and Schrock [Mo(N(3)N)] systems. For both [Mo(N(3)N)] and [Nb(P(2)N(2))], the intermediate dimer is calculated to lie lower in energy than the products, although the final N-N cleavage step is much less endothermic for [Mo(N(3)N)]. In contrast, every step of the reaction is favourable and the overall exothermicity is greatest for [Mo{N(R)Ar}(3)], and therefore this system is predicted to be most suitable for dinitrogen cleavage.

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Tripodal Amido Complexes: Molecular “Claws” in Main Group and Transition Metal Chemistry

Cited by 145 publications

References 46 publications

Ate complexes of Ge(II) and Sn(II) with bidentate ligands [LiE14(OCH2CH2NMe2)3]2 (E14=Ge, Sn): synthesis and structure

Ate complexes of Ge(II) and Sn(II) with bidentate ligands [LiE14(OCH2CH2NMe2)3]2 (E14=Ge, Sn): synthesis and structure

Exploiting Threefold Symmetry in Asymmetric Catalysis: The Case of Tris(oxazolinyl)ethanes (“Trisox”)

Dinitrogen Activation by Fryzuk’s [Nb(P₂N₂)] Complex and Comparison with the Laplaza–Cummins [Mo{N(R)Ar}₃] and Schrock [Mo(N₃N)] Systems

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Tripodal Amido Complexes: Molecular “Claws” in Main Group and Transition Metal Chemistry

Cited by 145 publications

References 46 publications

Ate complexes of Ge(II) and Sn(II) with bidentate ligands [LiE14(OCH2CH2NMe2)3]2 (E14=Ge, Sn): synthesis and structure

Ate complexes of Ge(II) and Sn(II) with bidentate ligands [LiE14(OCH2CH2NMe2)3]2 (E14=Ge, Sn): synthesis and structure

Exploiting Threefold Symmetry in Asymmetric Catalysis: The Case of Tris(oxazolinyl)ethanes (“Trisox”)

Dinitrogen Activation by Fryzuk’s [Nb(P2N2)] Complex and Comparison with the Laplaza–Cummins [Mo{N(R)Ar}3] and Schrock [Mo(N3N)] Systems

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Dinitrogen Activation by Fryzuk’s [Nb(P₂N₂)] Complex and Comparison with the Laplaza–Cummins [Mo{N(R)Ar}₃] and Schrock [Mo(N₃N)] Systems