Synthesis of asymmetric boron cations and resolution with As(C6H4P2)3- anion

Ryschkewitsch, G. E.; Garrett, James M.

doi:10.1021/ja01028a011

Cited by 33 publications

(18 citation statements)

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“…The racemic complex Δ,Λ-[As(cat) 3 ]H precipitated after three days in the form of colorless needless; yield 10.4 g, 87%. 16 The X-ray structure of this reagent, crystallized from p-dioxane-water mixtures, has been reported by others. 17…”

Section: δλ-[Asmentioning

confidence: 57%

Resolution and characterization of helicate dimer and trimer complexes of 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane with copper(i)

et al. 2013

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Complexation of copper(I) with the binucleating ligand, 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane, mphenpr, result in formation of helical dimers, [Cu2(mphenpr)2](2+). The resolution of the enantiomeric forms of the dimers has been carried out with Δ-[As(cat)3](-) as resolving agent and X-ray structures for two compounds, P-[Cu2(mphenpr)2](Δ-[As(cat)3])2 and P-[Cu2(mphenpr)2](Δ-[As(cat)3])2·4(CH3CN), are reported. The rate of racemization in poorly-coordinating solvents has been examined by (1)H NMR, and is slow. At saturating concentrations of [[Cu2(mphenpr)2](2+)] in acetonitrile, crystals of the helical trimeric complex [Cu3(mphenpr)3](ClO4)3 are obtained. The X-ray structure of the trimer is reported. This species has also been resolved. As with the helical dimer, racemization in poorly-coordinating solvents is slow, and circular dichroism and (1)H NMR spectra are reported. The absolute configuration of the resolved complex, P-[Cu3(mphenpr)3](Δ-[As(cat)3])3, has been determined by X-ray crystallography.

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Section: δλ-[Asmentioning

confidence: 57%

Resolution and characterization of helicate dimer and trimer complexes of 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane with copper(i)

et al. 2013

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“…Thus, a classical study by Ryschkewitsch and Garrett succeeded in the first resolution of a tetra-coordinated, stereogenic boron cation using crystallization methods starting from 102 , the halogenation product of the boronium salt 101 (Scheme 6). 56 Challenging aspects of this work included controlling the homogeneity and solubility of the intermediate boronium salts involving the manipulation of up to three different anions after halogenation, depending on the halogen source (Z = I − , ICl 2 − , PF 6 − , Br 3 − , Br − ). Solubility is especially important in the key anion metathesis from racemic 102 (Z = Br) and the chiral tris(catecholato)arsenate anion As(C 6 H 4 O 2 ) 3 − , leading eventually to the single enantiomer of the boronium hexafluorophosphate 103 (arbitrary absolute configuration shown).…”

Section: Borenium Ions and Stereogenic Boronmentioning

confidence: 99%

Cationic Tricoordinate Boron Intermediates: Borenium Chemistry from the Organic Perspective

2012

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CONTENTS 1. Introduction 4246 2. History of Borenium Ions: Often Considered, Seldom Confirmed 4247 2.1. Suspected Intermediates in B−N Protonation 4247 2.2. Hypothetical Isomers of Cl 3 B•NHMe 2 4247 2.3. The First Observable Borenium Salt 4247 2.4. Nucleophilic Substitution of X 3 B•NR 3 and Py•BF 2 X 4248 2.5. Aminoborenium Ions, Stabilization by n-Delocalization 4249 3. Recent Developments in the Generation of Observable Borenium Intermediates 4249 3.1. Electrophilic Activation by Protonation or by Lewis Acid Catalysis 4249 3.2. Halide Abstraction by a Halophile 4250 3.3. The Borinium−Borenium Interface: Gas-Phase Oxyborenium Ions 4251 3.4. Borenium Salt Generation by Hydride Abstraction 4251 3 . 4 . 1 . H y d r i d e A b s t r a c t i o n b y T r i s -(pentafluorophenyl)borane 4251 3.4.2. Hydride Abstracton by Trityl Salts 4252 3.4.3. Hydride-Bridged Borenium Salt Dimers 4252 3.5. Borenium Ion Generation by Nucleophilic Addition−Heterolysis 4253 4. Borenium Lewis Acidity vs Structure 4254 4.1. Experimental Evaluation of Lewis Acidity 4254 4.2. Computational Evaluation of Borenium Lewis Acidity 4255 5. Borenium Ions and Stereogenic Boron 4257 5.1. Racemization by Heterolysis 4257 5.2. Asymmetric Memory at Stereogenic Boron 4257 5.3. Chiral Salicylaldimine Boronate Complexes 4258 6. Enantioselective Catalysis and Chiral Borenium Ions 4259 6.1. The Dual Function of Oxazaborolidines in the CBS Reduction 4260 6.2. The Role of Borenium Species in Diels−Alder Catalysis 4261 6.3. Reactivity and Scope of Oxazaborolidine-Derived Diels−Alder Catalysts 4263 6.4. Miscellaneous Uses of Chiral Borenium Lewis Acid Catalysts 4265 7. Miscellaneous Applications of Borenium Lewis Acids 4266 7.1. B−O Activation 4266 7.2. Lewis Acidity and π-Conjugated Borenium Analogues 4267 7.3. π-Conjugated Borenium Analogues as Selective Anion Sensors 4268 7.4. Tricoordinate Boron in Structures Containing Metal Cations 4269 8. Borenium Reagents for C−B Bond Formation 4269 8.1. Borenium Ion Equivalents 4269 8.2. Do Borenium Ions Participate in Hydroboration Chemistry? 4270 8.3. Borenium Equivalents in Electrophilic Aromatic Borylation 4271 8.3.1. Intramolecular Borylation 4271 8.3.2. Intermolecular Borylation 4272 8.3.3. Recent Developments in Muetterties Borylation (BX3 plus Proton Scavenger) 4275 9. Extension of Borenium Chemistry to Neighboring Fields and Unusual Environments 4276 9.1. N-Heterocyclic Carbenes as Stabilizing Ligands for Borenium Salts 4276 9.2. Miscellaneous Related Topics Involving BH Species 4277 10. Summary 4278 Author Information 4279 Corresponding Author 4279 Notes 4279 Biographies 4279 Acknowledgments 4279 References 4279

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“…TRISCAT is easily accessible, but it epimerizes quickly in solution and loses its optical activity . However, TRISCAS was reported to be stable in solution and was resolved to Δ and Λ isomers using cinchonine and cinchonidine alkaloids, respectively. , Likewise, TRISPHAT was resolved with high diastereomeric excess using chiral alkaloids , and has been used in asymmetric chemistry as resolving agent for high levels of induction or recognition in molecular , or supramolecular processes . Surprisingly, they have been used so far only sparsely for the synthesis of materials .…”

Section: Introductionmentioning

confidence: 99%

Design and Study of Structural Linear and Nonlinear Optical Properties of Chiral [Fe(phen)₃]²⁺Complexes

et al. 2018

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The dependence of nonlinear optical properties upon the spin state in molecular switches is still an unexplored area. Chiral [Fe( phen)] complexes are excellent candidates for those studies because they are expected to show nonlinear optical properties of interest and at the same time show photoconversion to a short-lived metastable high-Spin state by ultrafast optical pumping. Herein, we present the synthesis, crystallographic, and spectroscopic comparison of chiral [Fe( phen)] complexes obtained with chiral anions, a new lipophilic derivative of the D-symmetric (As(tartrate)), and D-symmetric tris(catechol)phosphate(V) (TRISCAT), tris(catechol)arsenate(V) (TRISCAS), and 3,4,5,6-tetrachlorocatechol phosphate(V) (TRISPHAT). Complexes [Fe( phen)]( rac-TRISCAT) (2) and [Fe( phen)](X-TRISCAS) (X = rac (3), Δ (4), Λ (5)) were found to be isomorphous in the R32 Sohncke space group with twinning by inversion correlated with the starting chiral anion optical purity. The structures show the [Fe( phen)] complex interacting strongly along its 3-fold axis with two anions. Only the structure of a [Fe( phen)]( rac-TRISPHAT) solvate (6) could be obtained, which showed no particular anion/cation interaction contrary to what was observed previously in solution. The [Fe( phen)](X-As(tartrate)) (X = Δ (7), Λ (8), and racemic mixture (9)) crystallizes in enantiomorphic space groups P321/ P321 with the same solid-state packing. Dichroic electronic absorption studies evidenced racemization for all chiral complexes in solution due to ion pair dissociation, whereas the asymmetric induction is conserved in the solid state in KBr pellets. We evidenced on chiral complexes 4 and 5 strong nonlinear second harmonic generation, the intensity of which could be correlated with the complex electronic absorption.

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Synthesis of asymmetric boron cations and resolution with As(C6H4P2)3- anion

Cited by 33 publications

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Resolution and characterization of helicate dimer and trimer complexes of 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane with copper(i)

Resolution and characterization of helicate dimer and trimer complexes of 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane with copper(i)

Cationic Tricoordinate Boron Intermediates: Borenium Chemistry from the Organic Perspective

Design and Study of Structural Linear and Nonlinear Optical Properties of Chiral [Fe(phen)₃]²⁺Complexes

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Synthesis of asymmetric boron cations and resolution with As(C6H4P2)3- anion

Cited by 33 publications

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Resolution and characterization of helicate dimer and trimer complexes of 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane with copper(i)

Resolution and characterization of helicate dimer and trimer complexes of 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane with copper(i)

Cationic Tricoordinate Boron Intermediates: Borenium Chemistry from the Organic Perspective

Design and Study of Structural Linear and Nonlinear Optical Properties of Chiral [Fe(phen)3]2+Complexes

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Design and Study of Structural Linear and Nonlinear Optical Properties of Chiral [Fe(phen)₃]²⁺Complexes