Download Pi_acids_bases_part 1

Dougherty, D. A., Science, 1996, 271,163.
Red = most negative electrostatic potentials (most basic regions)
Blue = most positive electrostatic potentials (most acidic regions)
Dougherty et al., Proc. Natl. Acad. Sci. USA, Vol. 93, pp. 10566–10571, October
1996
Chemistry
R'
OR
R
N
Au
N
Au
RO
N
N
Au
OR
R'
Au
Au N
N
R
N
R
TR(bzim) R = CH2Ph
R = Et, R' = p-Tol
T R(carb)
Au
N
OR
R'
N
p base
F
F
F
Hg
F
F
F
p acid
Hg
F
F
Hg
F
TRHg
F
F
F
Burini; Fackler; Omary; Staples et al.
J. Am. Chem. Soc. 2000, 122, 1126411265.
DFT Calculations of Trinuclear Complexes
[Au(bzim)]3
Electrost. Pot. (a.u.)
-0.0300
0.0300
[Hg(C6F4)]3
Electrostatic Potential Surfaces
[Hg(C6F4)]3
green = positive
p-Electrostatic
interaction
[Au(bzim)]3
red = negative
ADF Calculations
{[Au(carb)]3}2
DIMER
Green= positive
Red=negative
SUPER WHOPPER!!
p base
p acid
p base
SUPRAMOLECULAR CHAIN ASSEMBLIES
p base
p acid
p base
p acid
Burini; Fackler; Omary; Staples et al. J. Am. Chem. Soc. 2000, 122, 11264-11265.
Solid-state example:
p acid
Hg1A
F
F
F
C33B
F
F
Hg
Hg
F
p base
F
Hg
F
+
C38
F
F
p acid
C39
C40A
C38A
p acid
F
F
C36
C40
Hg3
Hg1
p base
Hg2
 = 568 ± 8 ms (RT)
Luminescence intensity, arb. units
Phosphorescence at RT in the solid-state!!
550
600
650
Wavelength, nm
700
Complexation of [Hg(o-C6F4)]3, 1, with aromatic hydrocarbons…
RGB bright phosphorescent emissions for the 1:1 solid adducts
RT
1.pyrene (2)
Intensity, arb. units
77K
RT
1.naphthalene (3)
77K
RT
1.biphenyl (4)
77K
14
16
18
20
22
24
26
Wavenumber/103cm-1
Omary; Kassab; Haneline; Elbjeirami; Gabbai Inorg. Chem. 2003, 42, 2176-2178.
Au3(carb)3.octafluoronaphthalene
Au 3 (carb) 3 .Naphthalene-F 8
RT
 = 3.6 ms
p acid
p acid
Intensity, a.u.
p base
Au 3 (carb) 3 .Naphthalene-F 8
77K
p base
Naphthalene-F 8
77K (no lum. at RT)
450
500
550
Wavelength, nm
600
650
R
R= e-withdrawing (e.g., CF3)
R
makes it more of a p acid
N
N
M
N
N
R
M
M
N
N
R= e-releasing (e.g., Me; i-Pr; t-Bu)
 makes it more of a p base
R
R
M= Cu; Ag; Au
Metal effect??…
R
DFT-calculated electrostatic potentials mapped on the
electron density surfaces of M3Pz3 complexes.
Color code:
red=most negative= strong p base;
blue=most positive= strong p acid;
Yellow= neutral/weak p base
green=neutral/weak p acid
Cu3Pz3
Ag3Pz3,
Pz ligands here have R=Me groups on them all
Au3Pz3
All strong p acids
But given previous slide we think
that the Ag3 compound would be
the strongest p acid
Calculations done by Alex
Gonser, as a CHEM5610
classroom project last year.
Ligand effect:
SUMMARY
R
• R= e-withdrawing (e.g., CF3)
N
makes it more of a p acid
• R= e-releasing (e.g., Me; i-Pr; t-Bu)
N
M
N
N
R
M
M
 makes it more of a p base
Metal effect:
R
N
N
R
Relative p basicity: Au>Cu>Ag
Relative p acidity: Ag>Cu>Au
M= Cu; Ag; Au
If you want to react with naphthalene (p base),
what would you choose for R and M to form an
acid-base adduct?
R
R
Maha Eldabaja (4610 student here doing research in the Omary group)….just got
crystals of an adduct for [Ag(3,5-(CF3)2Pz)]3 with naphthalene and found that it
has green emission, consistent with naphthalene phosphorescence
Maha Eldabaja (4610 student here doing research in the Omary group)….just got
crystals of an adduct for [Ag(3,5-(CF3)2Pz)]3 with naphthalene and found that it
has green emission, consistent with naphthalene phosphorescence
Luminescence intensity, arb. units
(let’s hear it for Maha!!)
Chi2
: 1.032
Durbin Watson
: 1.85
Z
: 374.2
Pre-exp. 1
: 825.2
±1.638E+001
Lifetime 1 : 1.575E+004 ms
Offset
±6.652E+002
: 26.5
 = 15.8 ± 0.7 ms
450
500
550
600
Wavelength, nm
650
700