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Effets de sel en chimie organique et organométallique
Prof. Jérôme Lacour, Organic Chemistry Department
Université de Dijon, ICMUB, 20.03.08
Salts Effects in Organic and Organometallic Chemistry
Introduction and General Aspects
Kinetic effects in catalysis
Thermodynamic effects insupramolecular chemistry
Structural characterization
Perspectives
Salts Effects in Organic and Organometallic Chemistry
Introduction and General Aspects
Kinetic effects in catalysis
Thermodynamic effects insupramolecular chemistry
Structural Characterization
Perspectives
The Various Types of Ion Pairs
A+ X-
The Various Types of Ion Pairs
A+ X-
ContactTight
Intimate
SS
SS
S
S
SS
SS
S
LooseSolvent Separated
A+ X-S
The Various Types of Ion Pairs
A+ X-
ContactTight
Intimate
A+ X-S
LooseSolvent Separated
A+ X-
DISSOCIATION
S
SS
S
S
The Various Types of Ion Pairs
AGGREGATION
A+ X-
A+X-
A+ X-
A+X-
E E
+-
Penetrated
G. Boche, Angew. Chem., Int. Ed. Engl., 1992, 31, 731
A+ X-
ContactTight
Intimate
A+ X-S
LooseSolvent Separated
1. Donor Solvents – DN scaleSolvents possessing a lone pair (Lewis base)Strongly solvating cations
2. Acceptor Solvents – AN scaleLewis acid solvents accepting lone pairsand therefore solvating strongly anions
Donor and Acceptor Solvents
Importance of Solvents
1. Polar Protic (εr > 15)Dissociated Ions
2. Apolar Aprotic (εr < 15, μ < 2.5 D)Strongly Associated IP or Aggregates
3. Polar Aprotic (εr > 15, μ > 2.5 D)Dissociated Ions or Weakly Associated
Protic and Aprotic /Polar or Apolar Solvents
S : A+DN
S X-AN
Electrostatic Modulation
Coulombic Interactions
qq’1
r4 π εr
Eint =
εr = dielectric constant of the mediumr = distance between the two chargesq et q’ = charges
Applied to Ion Pairs
1qq’
εr r4 πEass =
εr = dielectric constant of the mediumr = sum of the ionic radii of the solvated speciesq et q’ = charge on each of the ions
A+ X-Contact
TightIntimate
A+ X-S
LooseSolvent Separated
High εrLow εr
Electrostatic Modulation
Minimum distance for nointeraction between two ions
εr = dielectric constant of the mediume = charge on the electronZ1, Z2 = Valence of the ionsk = Boltzmann constantT = absolute temperature (K)
Z1Z2e2
k T2 εr
dmin =
280
εr
dmin = (in Å at 25 °C)
A+ X-
H2O εr = 80 dmin = 3.6 Å Dissociated
DISSOCIATION
H2O
X-
C6H6 εr = 2 dmin = 140 Å IonicAssociation
A+Contact
TightIntimate
CIP
C6H6
dmin
« HSAB Symbiotic Effect »
H+ > Li+ > Na+ > K+ > Rb+ > Cs+
F- > Cl- > Br- > I-
Ph4As+ > Ph3C+ >> R4N+ > K+ > Na+ > Li+
Ph4B- > Ph3C- >> I- > Br- > Cl- > F-
A+
X-
« Hard » Ions
High charge density
Not bulkyLocalized chargeLow polarizability
A+
X-
« Soft » Ions
Low charge density
BulkyOften of delocalized chargeUsually Polarizable
A+ X- A+ X-
Pearson, R. G. J. Am. Chem. Soc. 1963, 85, 3533
« HSAB Symbiotic Effect »
Hard anions – Low HOMOsHard cations – Very high LUMOs
Interaction under Charge Control
The interaction between a hard cation and a hard anion or betweentwo soft ions is stronger than that between two ions of different type
A+
X-
« Hard » Ions
H+ > Li+ > Na+ > K+ > Rb+ > Cs+
F- > Cl- > Br- > I-
Soft anions – Very high HOMOsSoft cations – Low LUMOs
Interaction under Orbital Control
A+
X-
« Soft » Ions
Ph4As+ > Ph3C+ >> R4N+ > K+ > Na+ > Li+
Ph4B- > Ph3C- >> I- > Br- > Cl- > F-
Salts Effects in Organic and Inorganic Chemistry
Introduction and General Aspects
Kinetic effects in catalysis
Thermodynamic effects insupramolecular chemistry
Structural Characterization
Perspectives
Evans et al. Angew. Chem. Int. Ed. Engl. 1995, 34, 768
Diels-Alder Reactions
Evans et al. Angew. Chem. Int. Ed. Engl. 1995, 34, 768
Diels-Alder Reactions
Evans et al. Angew. Chem. Int. Ed. Engl. 1995, 34, 768
Diels-Alder Reactions
Diels-Alder Reactions
Note: temperature or anion effect ?
OTfSbF6OTfSbF6
ee 87% ~ rapport 14.4:1; ee 96% ~ rapport 49:1
Diels-Alder Reactions
Diels-Alder Reactions
SbF6- TfO-
Diels-Alder Reactions
Angew. Chem. Int. Ed. 1999, 38, 1220
CF3
CF3 4
B
BArF
Diels-Alder Reactions
3 CH···F interactions
Angew. Chem. Int. Ed. 1999, 38, 1220
Carbo and Hetero Diels-Alder Reactions
J. Chem. Soc., Perkin Trans. 2 1997, 1183
Carbo and Hetero Diels-Alder Reactions
DN ANDCM - 20.4MeNO2 2.7 20.5DMF 26.6 16.0
MeCN 14.1 18.9
THF 20.0 8.0
MeNO2 εr 35.9 CH2Cl2 εr 8.9
J. Chem. Soc., Perkin Trans. 2 1997, 1183
Angew. Chem. Int. Ed. 1998, 37, 2897
CF3
CF3 4
B
Moisture!
TOF: 1a 41 min-1 while 1e 70-135 min-1
Hydrovinylation Reactions
J. A. Chem. Soc. 1999, 121, 9899
ethylene (1 atm)0.35 mol% [(allyl)Ni-Br]2
Ph3P, AgOTf
Chem. Eur. J. 1999, 5, 1963.
ethylene (1 atm)0.7 mol% [(allyl)Ni-Br]2
R3P*, AgOTf∗
MeO MeO
PPh2
O
R = OMe, OBn
R
Hydrovinylation Reactions
J. A. Chem. Soc. 1999, 121, 9899
ethylene (1 atm)0.35 mol% [(allyl)Ni-Br]2
R3P, AgOTf
ethylene (1 atm)0.7 mol% [(allyl)Ni-Br]2
R3P*, NaBARF∗
MeO MeO
Chem. Eur. J. 1999, 5, 1963.
PPh2
O
R = OMe, OBn
R
No rxn with NaBARF
BARF
Hydrovinylation Reactions
J. A. Chem. Soc. 1999, 121, 9899
ethylene (1 atm)0.35 mol% [(allyl)Ni-Br]2
R3P, AgX
P
Me
MeX
5a H
5b OCH2Ph
5c CH2OCH2Ph
5d CH2OCH3
X
Hydrovinylation Reactions
J. Am. Chem. Soc. 1999, 121, 9899
H2C
XNi
H2C
HC
P
Ar
X = OTf, ClO4
H2C
X
NiH2C
HC
P
Ar
X = SbF6, BARF
5a
See also D. Voigt J. Organomet. Chem. 1998, 552, 187
H2C
ONi
H2C
HC
P
Ar
R
H2C
XNi
H2C
HC
P
Ar
RO
X = OTf, ClO4X = SbF6, BARF
5c
P
Me
MeX
5a H
5b OCH2Ph
5c CH2OCH2Ph
5d CH2OCH3
X
Salts Effects in Organic and Inorganic Chemistry
Introduction and General Aspects
Kinetic effects in catalysis
Thermodynamic effects insupramolecular chemistry
Structural Characterization
Perspectives
Cation-π interactions
NR
Host-Guest Chemistry
Böhmer, Collet, Ito, Kubik, Rebek, Sanders, Shinkai, etc.
A+X-
?
Initial Results
N 9
From chloride to iodide x 19 decrease
Quite bizarre
Tetrahedron Lett. 1998, 39, 3779
More complete stories
J. Am. Chem. Soc. 1999, 121, 11908J. Am. Chem. Soc. 2002, 124, 8307
Picrate > trifluoroacetate > I- >Br- > Cl- > tosylate > acetate
NO2
NO2O2NO
Explanation?
J. Am. Chem. Soc. 1999, 121, 11908J. Am. Chem. Soc. 2002, 124, 8307
Explanation?
J. Am. Chem. Soc. 1999, 121, 11908J. Am. Chem. Soc. 2002, 124, 8307
Ion pair dissociation energy
Guest appears to respond to the cation’s chargedensity exposed to the receptor, which is determinedby the anion’s charge density through a polarizationscheme
Not so simple, see Hunter Chem. Commun. 2003, 834
Beware – The whole ion pair may need to be considered
2 3
Δ-4 Λ-4
Beware – The whole ion pair may need to be considered
2 3
Δ-4 Λ-4
Salts Effects in Organic and Inorganic Chemistry
Introduction and General Aspects
Kinetic effects in catalysis
Thermodynamic effects insupramolecular chemistry
Structural Characterization
Perspectives
A+ X-
?
nOe and PGSEexperiments
NOEs and PGSE experiments
For organic compounds, see Pochapsky Magn. Reson. Chem. 2000, 38, 90 and incl. ref.
NOEs and PGSE experiments - Reviews
NOEs and PGSE experiments - Reviews
Qualitative NMR Investigations
Review : Euro. J. Inorg. Chem. 2003, 195
19F, 1H HOESY
Qualitative NMR Investigations
1H NOESY
Review : Euro. J. Inorg. Chem. 2003, 195
Qualitative NMR Investigations
R = H, R’’ = Me
R = i-Pr, R’’ = Me
Organometallics 1999, 18, 4367
X-
X-
Qualitative NMR Investigations
Organometallics 1999, 18, 3061
decreasing NOEsTfO- > BF4
- > PF6 - > BARF
For a recent account, see Chem.Eur. J. 2007, 13, 1570
Quantitative NMR Investigations
Organometallics 1999, 18, 1
From qualitative to quantitative information ?
Quantitative NMR Investigations
Organometallics 1999, 18, 1
Quantitative experiments – Diffusion Coefficients
Helv. Chim. Acta 2001, 84, 3833
CIP
Quantitative experiments – Diffusion Coefficients
Helv. Chim. Acta 2001, 84, 3833
CIP
SSIP
Quantitative experiments – Diffusion Coefficients
Ar = pTol, R = tBu
Chem. Commun. 2002, 286
Solvent CD2Cl2
anion
cation
Quantitative experiments – Diffusion Coefficients
Chem. Commun. 2002, 286
No strong ion-pairing in methylene chlorideAr = pTol, R = tBu
PGSE and aggregation studies
excess of MX- 2 MCl
Aggregation increases with non-coordinating anions such as BPh4−
PGSE and aggregation studies
excess of MX- 2 MCl
CD2Cl2
Salts Effects in Organic and Inorganic Chemistry
Introduction and General Aspects
Kinetic effects in catalysis
Thermodynamic effects insupramolecular chemistry
Structural Characterization
Perspectives
Towards Real Non-Coordinating Anions
Chem. Eur. J. 2002, 8, 2088
Towards Real Non-Coordinating Anions
Chem. Eur. J. 2002, 8, 2088
Towards Real Non-Coordinating Anions
Chem. Eur. J. 2002, 8, 2088
PPh3
(PPh3)2
Just a beautiful picture ?
Angew. Chem. 2003, 115, 3611
19F NMR δ –26 ppmAnhydrous [TBA][F] δ –73 ppm
Chiral counterions
Chiral counterions
Chiral counterions
PPh3 conv. 39% ee 64%P(o-tolyl)3 conv. 35% ee 74%
Chiral counterions
See also JACS 2006, 128, 13368
Chiral counterions
See also JACS 2006, 128, 13368
Chiral counterions
Chiral counterions
Chiral counterions
Acknowledgments
Merci pour votre attention
Martina AUSTERI; Renaud BACH; Rémy BERNARD; Frédéric BURON; Samuel CONSTANT; ValérieDESVERGNES-BREUIL; France FAVARGER; Richard FRANTZ; Helena GONCALVES-FARBOS; Catherine GOUJON-GINGLINGER; Stéphane GRASS; Virginie HEBBE-VITON; Christelle HERSE; Jonathan JODRY; Benoit LALEU; Nathalie L’HELIAS; David LINDER; Anne LONDEZ; Claire MARSOL; Alexandre MARTINEZ; Nathalie MEHANNA; Christophe MICHON; Pierre MOBIAN; David MONCHAUD; Jessica MULLER, Cyril NICOLAS; Roman NOVIKOV; Céline PEROLLIER; Dalit RECHAVI; Ankit SHARMA; Franck TORRICELLI; Simone TORTOIOLI; Jerome VACHON; Laurent VIAL; Walid ZEGHIDA