CHPC: 2013 National Meeting and Conference 2–6 December Cape Town International Convention Centre
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Transcript of 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
CHPC: 2013 National Meeting and Conference
2–6 December
Cape Town International
Convention Centre
Jeanet Conradie+27(0)51 401 2194 | [email protected] | www.ufs.ac.za
Density Functional Theory calculations with High Performance Computing predicts chemical reactivity.
Catalytic Application1.
This StudyRh(I)--diketonato
complexes
Monsanto Process[Rh(CO)2(I)2]
rate determining
1 electrochemical oxidation 2 substitution3 chemical oxidation
RhI
RhIII
The complexes
O
R'O
RhI
R
CO
PX3
PX3 = P(OCH2)3CCH3PX3 = PPh3
O
R'O
RhI
R
CO
CO
O
R'O
RhI
R
O
R'O
RhI
R
P(OPh)3
P(OPh)3
2.
CF3 (3.01) > CCl3 (2.76) > CH3 (2.34) > Ph (2.21) > Fc (1.87)
(high ) (low )
e- withdrawing e- donating
more electron donating
in terms ofsum of group
electronegativities R + R’
donate electron density via conjugation to Rh
FeIIFc =
CF3CF3 (11)
CH3CF3 (10)
PhCF3 (9)
FcCF3 (8)
CH3CH3 (7)
FcCCl3 (6)
PhCH3 (5)Ph Ph (4)
CH3Fc (3)Fc Ph (2)Fc Fc (1)R R'
O
R'O
RhI
R
X
Y
3.The complexes
O
R'
O
RhI
R
O
R'O
RhI
R
P(OPh)3
P(OPh)3O
R'O
RhI
R
CO
COO
R'O
RhI
R
CO
PR3
(3): PX3 = P(OCH2)3CCH3(4): PX3 = PPh3
(1)(2)(5)
Experimental: Electrochemical oxidation
electrochemical oxidation 1
electrochemical oxidation 3 and 4
electrochemical oxidation 5
electrochemical oxidation 2
4.
(7)
(10)
(11)
more electron donating
Rh(I) easier oxidized to Rh(III)
oxidation
-2eRhI RhIII
Experimental: Electrochemical oxidation 1
O
RO
RhIP(OPh)3
P(OPh)3
R'
one electro-active center
more electron donating
CF3CF3 (11)
CH3CF3 (10)
PhCF3 (9)
FcCF3 (8)
CH3CH3 (7)
PhCH3 (5)Ph Ph (4)
CH3Fc (3)Fc Ph (2)Fc Fc (1)R R'
5.
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
[RhI(RCOCHCOFc)(P(OPh)3)2] -2e-[RhIII(RCOCHCOFc)(P(OPh)3)2]2+ -1e-
[RhIII(RCOCHCOFc+)(P(OPh)3)2]3+
two electro-active centers
(3)
(8)
oxidation
-2eRhI RhIII
Experimental: Electrochemical oxidation 1
O
RO
RhIP(OPh)3
P(OPh)3
FeII
more electron donating
CF3CF3 (11)
CH3CF3 (10)
PhCF3 (9)
FcCF3 (8)
CH3CH3 (7)
PhCH3 (5)Ph Ph (4)
CH3Fc (3)Fc Ph (2)Fc Fc (1)R R'
6.
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
oxidation
-2eRhI RhIII
[RhI(RCOCHCOFc)(P(OPh)3)2] -2e-[RhIII(RCOCHCOFc)(P(OPh)3)2]2+ -1e-
[RhIII(RCOCHCOFc+)(P(OPh)3)2]3+
two electro-active centers
(3)
(8)
Experimental: Electrochemical oxidation 1
O
RO
RhIP(OPh)3
P(OPh)3
FeII
more electron donating
CF3CF3 (11)
CH3CF3 (10)
PhCF3 (9)
FcCF3 (8)
CH3CH3 (7)
PhCH3 (5)Ph Ph (4)
CH3Fc (3)Fc Ph (2)Fc Fc (1)R R'
(1) has three electro-active centers
7.
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
(1)
(3)
(8)
oxidation
-2eRhI RhIII
[RhI(RCOCHCOFc)(P(OPh)3)2] -2e-[RhIII(RCOCHCOFc)(P(OPh)3)2]2+ -1e-
[RhIII(RCOCHCOFc+)(P(OPh)3)2]3+
two electro-active centers
more electron donating
Rh(I) easier oxidized to Rh(III)
Experimental: Electrochemical oxidation 1
O
RO
RhIP(OPh)3
P(OPh)3
FeII
more electron donating
CF3CF3 (11)
CH3CF3 (10)
PhCF3 (9)
FcCF3 (8)
CH3CH3 (7)
PhCH3 (5)Ph Ph (4)
CH3Fc (3)Fc Ph (2)Fc Fc (1)R R'
(1) has three electro-active centers
8.
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.
oxidation
-2eRhI RhIII
more electron donating
Rh(I) easier oxidized to Rh(III)
[RhI(RCOCHCOR')(P(OPh)3)2] [RhIII(RCOCHCOR')(P(OPh)3)2]2+-2e-
Experimental: Electrochemical oxidation 1
O
R'O
RhI
R
P(OPh)3
P(OPh)3
more electron donating
CF3CF3 (11)
CH3CF3 (10)
PhCF3 (9)
FcCF3 (8)
CH3CH3 (7)
PhCH3 (5)Ph Ph (4)
CH3Fc (3)Fc Ph (2)Fc Fc (1)R R'
9.
LUMO
HOMO
oxidation
more electron donating
Rh(I) easier oxidized to Rh(III)
higher energy HOMO – electrons easier removed – easier oxidized
-2e-RhI RhIII
Oxidation of Rh(I) to Rh(III) corresponds to the removal of 2 electrons from the highest molecular orbital, the HOMO of the complex.
DFT and Electrochemical oxidation 110.
Gaussian 09 with B3LYP functional and 6-311G(d,p) basis set for C, H, O, F, P, Fe and Lanl2dz for Rh
LUMO
HOMO
oxidation
-2e-RhI RhIII
Oxidation of Rh(I) to Rh(III) corresponds to the removal of 2 electrons from the highest molecular orbital, the HOMO of the complex.
DFT and Electrochemical oxidation 1
more electron donating
Rh(I) easier oxidized to Rh(III)
higher energy HOMO – electrons easier removed – easier oxidized
11.
J. Conradie, Electro Chim. Acta 110 (2013) 718.
Experimental: Electrochemical oxidation 2
Rh Fc
y = 7.826x + 2.710
R2 = 0.963
2
3
4
5
6
0.0 0.1 0.2 0.3 0.4 0.5
E pa(Rh) / V
1+ 2
(Go
rdy
scal
e)
y = 8.053x + 2.193
R2 = 0.954
2
3
4
5
6
0.0 0.1 0.2 0.3 0.4 0.5
E 0/(Fc) / V
1+ 2
(G
ord
y sc
ale)
more electron donating
O
FcO
RhIII
R
O
R'O
RhI
R
O
R'O
RhIII
R
- 2e-
- e-+ e-
+
2+
3+
For R' = Fc
12.
CV data from: Conradie J. and Swarts J.C., Dalton Trans., 2011, 40, 5844-5851
DFT and Electrochemical oxidation 2
LUMO
HOMO
HOMO-1
• First oxidation: 2e- from HOMO (RhI to RhIII)
• Second oxidation: e- from HOMO-1 (Fc to Fc+)
-2e- -e-
O
FcO
RhIII
R
O
R'O
RhI
R
O
R'O
RhIII
R
- 2e-
- e-+ e-
+
2+
3+
For R' = Fc
CV data from: Conradie J. and Swarts J.C., Dalton Trans., 2011, 40, 5844-5851DFT: von Eschwege, K.G. and Conradie, J., S. Afr. J. Chem., 2011, 64, 203-209.
13.
DFT and Electrochemical oxidation 2
LUMO
HOMO
HOMO-1
• First oxidation: 2e- from HOMO (RhI to RhIII)
• Second oxidation: e- from HOMO-1 (Fc to Fc+)
-2e- -e-
O
FcO
RhIII
R
O
R'O
RhI
R
O
R'O
RhIII
R
- 2e-
- e-+ e-
+
2+
3+
For R' = Fc
higher energy HOMO – electrons easier removed – easier oxidized
14.
DFT and Electrochemical oxidation 3
O
R'
O
RhI
R
CO
P(OCH2)3CCH3
O
R'O
RhIII
R
CO
P(OCH2)3CCH3
- 2e-
2+
higher energy HOMOelectrons easier removed
easier oxidized
Erasmus, J.J.C. and Conradie, J., Dalton Transactions, 2013, 42, 8655–8666.
15.
DFT and Electrochemical oxidation 4
O
R'O
RhI
R
CO
PPh3
O
R'
O
RhIII
R
CO
PPh3
- 2e-
2+
Ferreira, H., Conradie, M.M. and Conradie, J., Electrochim. Acta, 2013, 113, 519-526.
higher energy HOMOelectrons easier removed
easier oxidized
16.
DFT and Electrochemical oxidation 5
CV data from: Conradie, J., et. al., Inorg. Chim. Acta., 358, 2005, 2530-2542.
O
FcO
RhI
R
CO
CO
O
Fc
O
RhI
R
CO
CO
O
FcO
RhIII
R
CO
CO
+
+ e- - e-
- 2e-
+
1+
3+
• HOMO on ferrocene
• First oxidation: e- from HOMO (Fc to Fc+)
17.
DFT and Electrochemical oxidation 5
CV data from: Conradie, J., et. al., Inorg. Chim. Acta., 358, 2005, 2530-2542.
O
FcO
RhI
R
CO
CO
O
Fc
O
RhI
R
CO
CO
O
FcO
RhIII
R
CO
CO
+
+ e- - e-
- 2e-
+
1+
3+
• HOMO on ferrocene
• First oxidation: e- from HOMO (Fc to Fc+)
18.
DFT and Electrochemical oxidation 5
CV data from: Conradie, J., et. al., Inorg. Chim. Acta., 358, 2005, 2530-2542.
higher energy HOMOelectrons easier removed
easier oxidized
O
FcO
RhI
R
CO
CO
O
Fc
O
RhI
R
CO
CO
O
FcO
RhIII
R
CO
CO
+
+ e- - e-
- 2e-
+
1+
3+
19.
DFT and Electrochemical oxidation: Summary20.
Experimental: Substitution reactions
O
R'
O
RhI
R
O
R'O
RhI
R
P(OPh)3
P(OPh)3O
R'O
RhI
R
CO
COO
R'O
RhI
R
CO
PR3
PX3 P(OPh)3
2CO
PX3 = P(OCH2)3CCH3PX3 = PPh3
21.
Experimental: Substitution reactions
• Experimental1 V# and large negative S#: – 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.
O
R'
O
RhI
R
O
R'O
RhI
R
P(OPh)3
P(OPh)3O
R'O
RhI
R
CO
COO
R'O
RhI
R
CO
PX3
N
N
N
N
Rh
+
PX3 P(OPh)3
2CO
PX3 = P(OCH2)3CCH3PX3 = PPh3 substitution 3 substitution 1
substitution 2
22.
Experimental and DFT: Substitution reaction 1
k2 from J.G. Leipoldt, G.J. Lamprecht and E.C. Steinberg, J. Organomet. Chem. 397 (1990) 239DFT from Conradie, J. Inorg. Chim. Acta, 2013, 406, 211-216.
• DFT calculated TS:– Associative mechanism– 5-coordinate TS – Rh is electron acceptor (electrophile)– electron withdrawing groups stabilize TS, more reactive
O
R'O
RhI
R
O
R'O
RhI
R
P(OPh)3
P(OPh)3
P(OPh)3
HOMOP(OPh)3
HOMORh()(cod)
TS
23.
Experimental and DFT: Substitution reaction 1
y = -0.125x - 3.728
R2 = 0.979
-5.0-4.9-4.8-4.7-4.6-4.5-4.4-4.3-4.2-4.1-4.0
0 5 10
lnk 2
EH
OM
O(c
alc)
/ eV
k2 from J.G. Leipoldt, G.J. Lamprecht and E.C. Steinberg, J. Organomet. Chem. 397 (1990) 239DFT from Conradie, J. Inorg. Chim. Acta, 2013, 406, 211-216.
• DFT calculated TS:– Associative mechanism– 5-coordinate TS – Rh is electron acceptor (electrophile)– electron withdrawing groups stabilize TS, more reactive
lower energy HOMOelectrons easier accepted
larger substitution k
O
R'O
RhI
R
O
R'O
RhI
R
P(OPh)3
P(OPh)3
P(OPh)3
24.
Experimental and DFT: Substitution reaction 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
y = -0.074x - 3.963
R2 = 0.978
-5.0
-4.8
-4.6
-4.4
-4.2
-4.0
0 5 10 15
lnk 2E
HO
MO(c
alc)
/ e
V
O
R'O
RhI
R
N
N
N
N
Rh
+
lower energy HOMOelectrons easier accepted
larger substitution k
25.
Experimental and DFT: Substitution reaction 3
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
O
R'O
RhI
R
O
R'O
RhI
R
CO
CO
lower energy HOMOelectrons easier accepted
larger substitution k
26.
Experimental: Oxidative addition
chemical oxidation 2
and 3
chemical oxidation 1
O
R'
O
RhI
R
O
R'O
RhI
R
P(OPh)3
P(OPh)3O
R'O
RhI
R
CO
COO
R'O
RhI
R
CO
PR3
P(OPh)3PX3
2CO
PX3 = P(OCH2)3CCH3PX3 = PPh3
CH3I
O
R'O
RhIII
CO
PX3
R
CH3
I
CH3I
O
R'O
RhIII
P(OPh)3
P(OPh)3R
CH3
I
27.
M.M. Conradie, J. Conradie, J. Organomet. Chem. 695 (2010) 2126.
Experimental and DFT: Oxidative addition 1
O
R'O
RhI
R
P(OPh)3
P(OPh)3
O
RO
RhP(OPh)3
R'
CH3
I
P(OPh)3
+CH3Ik2
• DFT calculated TS:– Associative mechanism
28.
M.M. Conradie, J. Conradie, J. Organomet. Chem. 695 (2010) 2126.
Experimental and DFT: Oxidative addition 1
O
R'O
RhI
R
P(OPh)3
P(OPh)3
O
RO
RhP(OPh)3
R'
CH3
I
P(OPh)3
+CH3Ik2
• DFT calculated TS:– Associative mechanism
29.
M.M. Conradie, J. Conradie, J. Organomet. Chem. 695 (2010) 2126.
Experimental and DFT: Oxidative addition 1
O
R'O
RhI
R
P(OPh)3
P(OPh)3
O
RO
RhP(OPh)3
R'
CH3
I
P(OPh)3
+CH3Ik2
• DFT calculated TS:– Associative mechanism– Rh nucleophile– electron donating groups makes Rh more electron rich,
i.e more reactive towards o.a.
higher energy HOMOelectrons easier donated
larger oxidative addition k
29.
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) 223-227M.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 1
O
R'O
RhI
R
P(OPh)3
P(OPh)3
O
RO
RhP(OPh)3
R'
CH3
I
P(OPh)3
+CH3Ik2
higher energy HOMOelectrons easier donated
larger oxidative addition k
30.
Experimental and DFT: Oxidative addition 2
O
RO
RhCO
R'
CH3
I
P(OCH2)3CCH3
O
R'
O
RhI
R
CO
P(OCH2)3CCH3
+CH3Ik2
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.
more electron donating
Rh(I) easier oxidized to Rh(III)
higher energy HOMOelectrons easier donated
larger oxidative addition k
31.
2
Experimental and DFT: Oxidative addition 3
O
RO
RhCO
R'
CH3
I
PPh3
O
R'O
RhI
R
CO
PPh3
+CH3Ik2
more electron donating
Rh(I) easier oxidized to Rh(III)
higher energy HOMOelectrons easier donated
larger oxidative addition kk2 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 kinetics33.
• 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.
Conclusion
O
R'O
RhI
R
X
Y
34.
The Chemistry Department at the UFSfor available facilities
HPC Warehouse Facility of the UFS for computational facilities
The National Research Foundationfor financial support
CTCC and the University of Tromsøfor computational facilities
+27(0)51 401 2194 | [email protected] | www.ufs.ac.za
Experimental: Chemical- and Electrochemical oxidation and Substitution reactions
substitution 1 substitution 2
substitution 3chemical
oxidation 1 and 2
chemical oxidation 3
electrochemical oxidation 1
electrochemical oxidation 3 and 4
electrochemical oxidation 2
electrochemical oxidation 2
O
R'
O
RhI
R
O
R'O
RhI
R
P(OPh)3
P(OPh)3O
R'O
RhI
R
CO
COO
R'O
RhI
R
CO
PR3
PX3 P(OPh)3
2CO
PX3 = P(OCH2)3CCH3PX3 = PPh3
O
R'O
RhIII
CO
PX3
R
CH3
I
CH3I
N
N
N
N
Rh
+
O
R'O
RhIII
P(OPh)3
P(OPh)3R
CH3
I
CH3I
Experimental parameters related to oxidation potential of [Rh(RCOCHCOR')(P(OPh)3)2] 1 oxidation potential (Epa) of Rh2 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 () of R and R’ groups6 Hammett values (meta) of R and R’ groups7 pKa of the -diketone (RCOCH2COR’)
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 )
DFT and Electrochemical oxidation 1
O
R'O
RhI
R
P(OPh)3
P(OPh)3