Transcript Slide 1

CHPC: 2013 National
Meeting and
Conference
2–6 December
Cape Town
International
Convention Centre
T: +27(0)51 401 9111 | [email protected] | www.ufs.ac.za
+27(0)51 401 2194 | [email protected] | www.ufs.ac.za
Density Functional Theory calculations
with High Performance Computing
predicts chemical reactivity.
Jeanet Conradie
1.
Catalytic Application
Monsanto Process
[Rh(CO)2(I)2]-
This Study
Rh(I)-b-diketonato
complexes
rate
determining
Rh
Rh
I
III
1 electrochemical oxidation
2 substitution
3 chemical oxidation
2.
The complexes
R'
R'
CO
O
RhI
Rh
CO
O
R
P(OPh)3
O
I
P(OPh)3
O
R
R'
R'
RhI
I
Rh
O
R
CO
O
O
O
PX3
R
PX3 = P(OCH2)3CCH3
PX3 = PPh3
3.
The complexes
R'
X
O
RhI
O
Y
R
donate electron density
via conjugation to Rh
more
electron
donating
in terms of
sum of group
electronegativities
cR + cR’
R
Fc
Fc
Fc
Ph
CH3
R'
Fc
Ph
CH3
Ph
Ph
CCl3 Fc
(1)
(2)
(3)
(4)
(5)
(6)
CH3 CH3 (7)
CF3 Fc
(8)
CF3 Ph
(9)
CF3 CH3 (10)
CF3 CF3 (11)
cCF3 (3.01) > cCCl3 (2.76) > cCH3 (2.34) > cPh (2.21) > cFc (1.87)
(high c)
e- withdrawing
(low c)
e- donating
Fc = FeII
4.
Experimental: Electrochemical oxidation
R'
CO
O
CO
O
I
R
(3): PX3 = P(OCH2)3CCH3
(4): PX3 = PPh3
electrochemical
oxidation 3 and 4
Rh
Rh
CO
O
I
I
Rh
PR3
(5)
electrochemical
oxidation 5
P(OPh)3
O
O
R
R
R
P(OPh)3
O
O
I
Rh
O
R'
R'
R'
(2)
electrochemical
oxidation 2
(1)
electrochemical
oxidation 1
Experimental: Electrochemical oxidation 1
I oxidation
III
Rh
- Rh
-2e
(11)
R
O
I
(10)
P(OPh)3
Rh
P(OPh)3
O
R'
one electro-active center
R
Fc
Fc
Fc
Ph
CH3
R'
Fc
Ph
CH3
Ph
Ph
(1)
(2)
(3)
(4)
(5)
CH3 CH3 (7)
(8)
CF3 Fc
(9)
CF3 Ph
CF3 CH3 (10)
CF3 CF3 (11)
(7)
more electron donating
more
electron
donating
Rh(I) easier oxidized to Rh(III)
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
5.
Experimental: Electrochemical oxidation 1
I
[Rh (RCOCHCOFc)(P(OPh)3)2]
-2e-
III
[Rh (RCOCHCOFc)(P(OPh)3)2]
I oxidation
III
Rh
- Rh
-2e
R
O
Rh
I
FeII
R
Fc
Fc
Fc
Ph
CH3
-1e-
[RhIII(RCOCHCOFc+)(P(OPh)3)2]3+
(8)
P(OPh)3
P(OPh)3
O
2+
(3)
two electro-active centers
R'
Fc
Ph
CH3
Ph
Ph
(1)
(2)
(3)
(4)
(5)
CH3 CH3 (7)
(8)
CF3 Fc
(9)
CF3 Ph
CF3 CH3 (10)
CF3 CF3 (11)
6.
more
electron
donating
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
Experimental: Electrochemical oxidation 1
I
[Rh (RCOCHCOFc)(P(OPh)3)2]
-2e-
III
[Rh (RCOCHCOFc)(P(OPh)3)2]
I oxidation
III
Rh
- Rh
-2e
R
O
Rh
I
FeII
R
Fc
Fc
Fc
Ph
CH3
-1e-
[RhIII(RCOCHCOFc+)(P(OPh)3)2]3+
(8)
P(OPh)3
P(OPh)3
O
2+
(3)
two electro-active centers
(1) has three electro-active centers
R'
Fc
Ph
CH3
Ph
Ph
(1)
(2)
(3)
(4)
(5)
CH3 CH3 (7)
(8)
CF3 Fc
(9)
CF3 Ph
CF3 CH3 (10)
CF3 CF3 (11)
7.
more
electron
donating
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
Experimental: Electrochemical oxidation 1
I
[Rh (RCOCHCOFc)(P(OPh)3)2]
-2e-
III
2+
[Rh (RCOCHCOFc)(P(OPh)3)2]
-1e-
[RhIII(RCOCHCOFc+)(P(OPh)3)2]3+
I oxidation
III
Rh
- Rh
-2e
(8)
R
O
Rh
I
FeII
R
Fc
Fc
Fc
Ph
CH3
P(OPh)3
P(OPh)3
O
(3)
two electro-active centers
(1) has three electro-active centers
R'
Fc
Ph
CH3
Ph
Ph
(1)
(2)
(3)
(4)
(5)
CH3 CH3 (7)
(8)
CF3 Fc
(9)
CF3 Ph
CF3 CH3 (10)
CF3 CF3 (11)
(1)
more electron donating
more
electron
donating
8.
Rh(I) easier oxidized to Rh(III)
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
Experimental: Electrochemical oxidation 1
[RhI(RCOCHCOR')(P(OPh)3)2]
-2e-
[RhIII(RCOCHCOR')(P(OPh)3)2]2+
I oxidation
III
Rh
- Rh
-2e
R'
P(OPh)3
O
RhI
O
P(OPh)3
R
R
Fc
Fc
Fc
Ph
CH3
R'
Fc
Ph
CH3
Ph
Ph
(1)
(2)
(3)
(4)
(5)
CH3 CH3 (7)
(8)
CF3 Fc
(9)
CF3 Ph
CF3 CH3 (10)
CF3 CF3 (11)
more electron donating
more
electron
donating
Rh(I) easier oxidized to Rh(III)
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
9.
10.
DFT and Electrochemical oxidation 1
Oxidation of Rh(I) to Rh(III) corresponds to the removal of 2 electrons
from the highest molecular orbital, the HOMO of the complex.
I
Rh
LUMO
HOMO
higher energy HOMO – electrons easier removed – easier oxidized
more electron donating
Rh(I) easier oxidized to Rh(III)
Gaussian 09 with B3LYP functional and 6-311G(d,p) basis set for C, H, O, F, P, Fe and Lanl2dz for Rh
oxidation
-
-2e
III
Rh
11.
DFT and Electrochemical oxidation 1
Oxidation of Rh(I) to Rh(III) corresponds to the removal of 2 electrons
from the highest molecular orbital, the HOMO of the complex.
I
Rh
LUMO
HOMO
higher energy HOMO – electrons easier removed – easier oxidized
more electron donating
Rh(I) easier oxidized to Rh(III)
J. Conradie, Electro Chim. Acta 110 (2013) 718.
oxidation
-
-2e
III
Rh
12.
Experimental: Electrochemical oxidation 2
R'
R
- 2e2+
R'
O
RhIII
O
R
+e
-
+
Fc
For R' = Fc
- e3+
more electron donating
O
6
5
4
y = 7.826x + 2.710
R2 = 0.963
3
2
0.0
0.1
0.2
0.3
0.4
6
5
4
y = 8.053x + 2.193
R2 = 0.954
3
2
0.0
0.1
0.2
0.3
0.4
E 0/(Fc) / V
O
RhIII
O
R
0.5
E pa(Rh) / V
c1+c2 (Gordy scale)
RhI
c1+c2 (Gordy scale)
Rh Fc
O
CV data from: Conradie J. and Swarts J.C., Dalton Trans., 2011, 40, 5844-5851
0.5
DFT and Electrochemical oxidation 2
R'
LUMO
O
Rh
I
O
-2e-
-e-
HOMO
R
HOMO-1
- 2e2+
R'
O
RhIII
O
R
+e
-
+
Fc
For R' = Fc
- e3+
O
RhIII
O
R
•
•
First oxidation: 2e- from HOMO (RhI to RhIII)
Second oxidation: e- from HOMO-1 (Fc to Fc+)
CV data from: Conradie J. and Swarts J.C., Dalton Trans., 2011, 40, 5844-5851
DFT: von Eschwege, K.G. and Conradie, J., S. Afr. J. Chem., 2011, 64, 203-209.
13.
DFT and Electrochemical oxidation 2
R'
LUMO
O
Rh
I
O
-2e-
-e-
HOMO
R
HOMO-1
- 2e2+
R'
O
RhIII
O
R
+e
-
+
Fc
For R' = Fc
- e3+
O
RhIII
O
R
•
•
First oxidation: 2e- from HOMO (RhI to RhIII)
Second oxidation: e- from HOMO-1 (Fc to Fc+)
higher energy HOMO – electrons easier removed – easier oxidized
14.
DFT and Electrochemical oxidation 3
15.
R'
CO
O
RhI
O
P(OCH2)3CCH3
R
- 2e2+
R'
O
CO
RhIII
P(OCH2)3CCH3
O
R
higher energy HOMO
electrons easier removed
easier oxidized
Erasmus, J.J.C. and Conradie, J., Dalton Transactions, 2013, 42, 8655–8666.
DFT and Electrochemical oxidation 4
16.
R'
CO
O
RhI
O
PPh3
R
- 2e2+
R'
O
CO
RhIII
PPh3
O
R
higher energy HOMO
electrons easier removed
easier oxidized
Ferreira, H., Conradie, M.M. and Conradie, J., Electrochim. Acta, 2013, 113, 519-526.
DFT and Electrochemical oxidation 5
17.
Fc
CO
O
Rh
I
O
CO
+ e-
- e-
R
1+
+
Fc
CO
O
Rh
O
I
CO
R
- 2e+
Fc
3+
O
CO
RhIII
CO
O
R
•
•
HOMO on ferrocene
First oxidation: e- from HOMO (Fc to Fc+)
CV data from: Conradie, J., et. al., Inorg. Chim. Acta., 358, 2005, 2530-2542.
DFT and Electrochemical oxidation 5
18.
Fc
CO
O
Rh
I
O
CO
+ e-
- e-
R
1+
+
Fc
CO
O
Rh
O
I
CO
R
- 2e+
Fc
3+
O
CO
RhIII
CO
O
R
•
•
HOMO on ferrocene
First oxidation: e- from HOMO (Fc to Fc+)
CV data from: Conradie, J., et. al., Inorg. Chim. Acta., 358, 2005, 2530-2542.
DFT and Electrochemical oxidation 5
19.
Fc
CO
O
Rh
I
O
CO
+ e-
- e-
R
1+
+
Fc
CO
O
Rh
O
I
CO
R
- 2e+
Fc
3+
O
CO
RhIII
CO
O
R
higher energy HOMO
electrons easier removed
easier oxidized
CV data from: Conradie, J., et. al., Inorg. Chim. Acta., 358, 2005, 2530-2542.
DFT and Electrochemical oxidation: Summary
20.
21.
Experimental: Substitution reactions
R'
CO
O
I
PX3
CO
O
O
I
I
Rh
O
R'
R'
R'
PR3
R
PX3 = P(OCH2)3CCH3
PX3 = PPh3
O
R
I
Rh
Rh
Rh
CO
2CO
O
O
R
P(OPh)3
O
P(OPh)3
R
P(OPh)3
22.
Experimental: Substitution reactions
R'
O
I
PX3
CO
O
O
I
I
Rh
O
R'
R'
R'
CO
R
PX3 = P(OCH2)3CCH3
PX3 = PPh3
O
R
I
Rh
Rh
Rh
PX3
CO
2CO
O
O
R
R
substitution 3
substitution 1
N
P(OPh)3
O
P(OPh)3
P(OPh)3
substitution 2
N
+
N
Rh
N
• Experimental1 DV# and large negative DS#:
– associative mechanism involving the formation of a 5-c species.
• The FMO Theory simplifies reactions to interactions between
frontier orbitals.
1 J.G. Leipoldt, E.C. Steynberg, R. van Eldik, Inorg. Chem. 26 (1987) 3068.
Experimental and DFT: Substitution reaction 1
23.
R'
O
RhI
O
R
P(OPh)3
R'
P(OPh)3
O
TS
RhI
O
P(OPh)3
R
• DFT calculated TS:
HOMO
HOMO
– Associative mechanism
P(OPh)3
Rh(b)(cod)
– 5-coordinate TS
– Rh is electron acceptor (electrophile)
– electron withdrawing groups stabilize TS, more reactive
k2 from J.G. Leipoldt, G.J. Lamprecht and E.C. Steinberg, J. Organomet. Chem. 397 (1990) 239
DFT from Conradie, J. Inorg. Chim. Acta, 2013, 406, 211-216.
24.
Experimental and DFT: Substitution reaction 1
R'
O
RhI
O
R
P(OPh)3
P(OPh)3
O
RhI
O
R
P(OPh)3
lower energy HOMO
electrons easier accepted
larger substitution k
E HOMO(calc) / eV
R'
-4.0
-4.1
-4.2
-4.3
-4.4
-4.5
-4.6
-4.7
-4.8
-4.9
-5.0
y = -0.125x - 3.728
• DFT calculated TS:
R2 = 0.979
– Associative mechanism
0
5
– 5-coordinate TS
lnk 2
– Rh is electron acceptor (electrophile)
– electron withdrawing groups stabilize TS, more reactive
10
k2 from J.G. Leipoldt, G.J. Lamprecht and E.C. Steinberg, J. Organomet. Chem. 397 (1990) 239
DFT from Conradie, J. Inorg. Chim. Acta, 2013, 406, 211-216.
Experimental and DFT: Substitution reaction 2
25.
R'
O
RhI
O
R
N
-4.0
+
N
Rh
N
lower energy HOMO
electrons easier accepted
larger substitution k
E HOMO(calc) / eV
N
y = -0.074x - 3.963
R2 = 0.978
-4.2
-4.4
-4.6
-4.8
-5.0
0
5
10
lnk 2
k2 from J.G. Leipoldt and E. C. Grobler, Trans. Met. Chem. 11 (1986) 110
and T.G. Vosloo, W.C. Du Plessis, J.C. Swarts, Inorg. Chim. Acta 331 (2002) 188.
DFT from Conradie, J. J. Organomet. Chem. 2012, 719, 8-13
15
Experimental and DFT: Substitution reaction 3
R'
CO
O
RhI
O
CO
R
R'
O
RhI
O
lower energy HOMO
electrons easier accepted
larger substitution k
R
k2 from J.G. Leipoldt, S.S. Basson, J.J.J. Schlebush and, E.C. Grobler Inorg. Chim. Acta., 1982, 62, 113–115.
DFT from Conradie, S. Afr. J. Chem; 2013, 66, 54-59
26.
27.
Experimental: Oxidative addition
R'
CO
O
I
PX3
chemical
oxidation 2
and 3
CH3
O
R
Rh
Rh
2CO
I
P(OPh)3
O
O
R
R
chemical
oxidation 1
CH3I
CH3
R'
P(OPh)3
O
III
RhIII
PX3
O
I
Rh
CO
P(OPh)3
O
P(OPh)3
CO
O
R
I
Rh
R
PX3 = P(OCH2)3CCH3
PX3 = PPh3
R'
O
I
PR3
CH3I
CO
O
Rh
O
R'
R'
R'
P(OPh)3
O
R
I
Experimental and DFT: Oxidative addition 1
28.
R'
P(OPh)3
O
Rh
O
I
P(OPh)3
R
k2
R
R'
+CH3I
CH3
O
P(OPh)3
Rh
P(OPh)3
O
I
• DFT calculated TS:
– Associative mechanism
M.M. Conradie, J. Conradie, J. Organomet. Chem. 695 (2010) 2126.
Experimental and DFT: Oxidative addition 1
29.
R'
P(OPh)3
O
Rh
O
I
P(OPh)3
R
k2
R
R'
+CH3I
CH3
O
P(OPh)3
Rh
P(OPh)3
O
I
• DFT calculated TS:
– Associative mechanism
M.M. Conradie, J. Conradie, J. Organomet. Chem. 695 (2010) 2126.
Experimental and DFT: Oxidative addition 1
29.
R'
P(OPh)3
O
Rh
O
I
P(OPh)3
R
k2
R
R'
+CH3I
CH3
O
P(OPh)3
Rh
P(OPh)3
O
I
• DFT calculated TS:
higher energy HOMO
– Associative mechanism
electrons easier donated
– Rh nucleophile
larger oxidative addition k
– electron donating groups makes Rh more electron rich,
i.e more reactive towards o.a.M.M. Conradie, J. Conradie, J. Organomet. Chem. 695 (2010) 2126.
Experimental and DFT: Oxidative addition 1
30.
R'
P(OPh)3
O
RhI
O
P(OPh)3
R
k2
R
R'
+CH3I
CH3
O
P(OPh)3
Rh
P(OPh)3
O
I
higher energy HOMO
electrons easier donated
larger oxidative addition k
more electron donating
Rh(I) easier oxidized to Rh(III)
k2 from: G.J. Van Zyl, G.J. Lamprecht, J.G. Leipoldt, T.W. Swaddle, Inorg. Chim. Acta 143 (1988) 223-227
M.M. Conradie, J.J.C. Erasmus, J. Conradie, Polyhedron 30 (2011) 2345.
DFT from Conradie, J., Electrochimica Acta; 2013, 110, 718-725
Experimental and DFT: Oxidative addition 2
R'
CO
O
Rh
O
I
P(OCH2)3CCH3
R
k2
R
R'
+CH3I
CH3
O
CO
Rh
P(OCH2)3CCH3
O
I
higher energy HOMO
electrons easier donated
larger oxidative addition k
2
more electron donating
Rh(I) easier oxidized to Rh(III)
Erasmus, J.J.C. and Conradie, J., Inorg. Chim. Acta; 2011, 375, 128-134
Erasmus, J.J.C. and Conradie, J., Cent. Eur. J. Chem. 2012, 10(1) 256-566.
Erasmus, J.J.C., Conradie, M.M. and Conradie, J., Reac. Kinet. Cat. Lett. 2012, 105(2) 233-249.
Erasmus, J.J.C. and Conradie, J., Dalton Transactions, 2013, 42, 8655–8666.
31.
Experimental and DFT: Oxidative addition 3
R'
CO
O
RhI
O
PPh3
R
k2
R
R'
+CH3I
CH3
O
CO
Rh
PPh3
O
I
higher energy HOMO
electrons easier donated
larger oxidative addition k
more electron donating
Rh(I) easier oxidized to Rh(III)
k2 from:Basson, S. S.; Leipoldt, J. G.; Roodt, A.; Venter, J. A.; van der Walt, T. J. Inorg. Chim. Acta, 1986, 119, 35.
Conradie, J., Lamprecht, G.J., Roodt, A. and Swarts, J.C. Polyhedron, 23, 2007, 5075-5087.
Conradie, M.M. and Conradie, J. Inorg. Chim. Acta., 2008, 361, 208-218 and 2008, 361, 2285-2295.
Stuurman, N.F. and Conradie, J. J Organomet. Chem., 2009, 694, 259-268.
Conradie, J. and Swarts, J.C. Organometallics, 2009, 28 (4), 1018-1026.
DFT Conradie, J., unpublished
32.
Experimental and DFT: Summary kinetics
33.
Conclusion
34.
R'
X
O
RhI
O
Y
R
• The stability/reactivity of the HOMO of [Rh(RCOCHCOR')(XY)]
complexes is related to the electronic influence of R and R' on Rh
– more electron donating, higher HOMO energy
• The energy of the HOMO of [Rh(RCOCHCOR')(XY)] relates to:
– experimental electrochemical oxidation potential
– experimental substitution kinetic rate constants
– experimental oxidative addition kinetic rate constants
• Close correlation between the experimental and the theoretical
descriptors enable the design of related rhodium complexes with a
particular reactivity.
The Chemistry Department at the UFS
for available facilities
HPC Warehouse Facility of the UFS
for computational facilities
CTCC and the University of Tromsø
for computational facilities
The National Research Foundation
for financial support
+27(0)51 401 2194 | [email protected] | www.ufs.ac.za
Experimental: Chemical- and Electrochemical
oxidation and Substitution reactions
R'
CO
O
PX3
I
R'
R'
R'
CO
O
O
Rh
PR3
O
O
R
PX3 = P(OCH2)3CCH3
PX3 = PPh3
electrochemical
oxidation 3 and 4
I
Rh
Rh
Rh
CO
2CO
R
substitution 1
substitution 2
electrochemical
oxidation 2
P(OPh)3
O
O
R
R
P(OPh)3
O
P(OPh)3
I
I
electrochemical
oxidation 2
electrochemical
oxidation 1
N
chemical
oxidation 1
and 2
CH3I
PX3
O
I
CH3
R'
P(OPh)3
O
Rh
Rh
N
RhIII
CH3I
+
CO
O
R
substitution 3
N
CH3
R'
chemical
oxidation 3
N
P(OPh)3
O
R
III
I
DFT and Electrochemical oxidation 1
Experimental parameters related to oxidation potential of [Rh(RCOCHCOR')(P(OPh)3)2]
1 oxidation potential (Epa) of Rh
2 kinetic rate constant (k2) of oxidative addition reaction
Calculated parameter related to oxidation potential of [Rh(RCOCHCOR')(P(OPh)3)2]
3 energy of HOMO (EHOMO)
4 calculated NPA charge on Rh(P(OPh)3)2
Parameters used to describe electron donating power (RCOCHCOR’)5 group electronegativity (c) of R and R’ groups
R'
6 Hammett values (meta) of R and R’ groups
O
7 pKa of the b-diketone (RCOCH2COR’)
O
R
Empirical relationship describing redox potential
8 Lever ligand parameter Eredox (vs. SHE) = SM X ΣEL + IM
(ΣEL=sum of the values of the ligand EL parameter for all the ligands )
P(OPh)3
RhI
P(OPh)3