Outline Basic Models Wed - - PDF document

▶
outline
SMART_READER_LITE
LIVE PREVIEW

Outline Basic Models Wed - - PDF document

Mar 31, 2023 112 likes •282 views

College Toegepaste Quantumchemie 2017 KS-DFT Chemische Binding Reactiviteit F. Matthias Bickelhaupt Outline Basic Models Wed 4 Oct 1. KS MO theory and Activation

slide-1
SLIDE 1

College Toegepaste Quantumchemie 2017

KS-DFT – Chemische Binding – Reactiviteit

  • F. Matthias Bickelhaupt

Outline

ASM in action: bond activation

  • 2. Bite Angle and Bite-Angle Flexibility
  • 1. KS MO theory and Activation Strain model
  • 3. d regime and s regime catalysts

Basic Models Structure, Bonding & Reactivity

–––––––––––––––––––––––– Wed 4 Oct ––––– Wed 11 Oct

30

slide-2
SLIDE 2

Part 2

Wed 11 Oct

31

Fragment-oriented Design

  • f Catalysts for C–X Activation

2: Improve with ligands:

X

M

X

M M + CH3–X

X MLn X MLn MLn + CH3–X

1: Intrinsic reactivity:

  • J. Chem. Theory Comput. 2005, 1, 286
  • J. Organomet. Chem. 2005, 690, 2191

32

slide-3
SLIDE 3

2 - Bite Angle & Bite-Angle Flexibility

33

Bite Angle:

steric nature

34

slide-4
SLIDE 4

Bidentate Ligands

and the Steric Nature of the Bite Angle

  • Chem. Eur. J. (communication) 2009, 15, 6112
  • ChemPhysChem. 2007, 8, 1170

Methane C–H activation:

  • ligands raise barriers
  • smaller bite angle

è lower barrier

L L M 180° L L M < 180°

35

Bidentate Ligands

and the Steric Nature of the Bite Angle

  • Chem. Eur. J. (communication) 2009, 15, 6112
  • ChemPhysChem. 2007, 8, 1170

Bite-Angle Effect according to literature:

"dπ" σ*C-X

  • ligands push d AOs up

è better HOMO–LUMO interaction

  • this view is not entirely

exact

36

slide-5
SLIDE 5

Bidentate Ligands

and the Steric Nature of the Bite Angle

  • Chem. Eur. J. (communication) 2009, 15, 6112
  • ChemPhysChem. 2007, 8, 1170

Bite-Angle Effect: Activation Strain analyses:

  • HOMO–LUMO interaction only

marginally improved

37

Ligands

  • J. Organomet. Chem. 2005, 690, 2191

38

slide-6
SLIDE 6

Bidentate Ligands

and the Steric Nature of the Bite Angle

  • Chem. Eur. J. (communication) 2009, 15, 6112
  • Org. Biomol. Chem. 2010, 8, 3118

Nature Chem. 2010, 2, 417

Bite-Angle Effect: Activation Strain analyses:

  • HOMO–LUMO interaction

marginally improved

  • Instead:

Strain reduced by building it into catalyst

39

Variation M and L

  • Oxidative addition with non-chelating d10-ML2 complexes
  • Metal variation: metals around Pd in the periodic table:
  • Ligand variation: NH3, PH3 or CO

Co– Ni Cu+ Rh– Pd Ag+ Ir– Pt Au+

  • Text Books: d10-ML2 is in general linear

L M L' L M L' L M L'

ChemistryOpen 2013, 2, 106

slide-7
SLIDE 7

Non-Linear d10-ML2

L-M-L ∆Elin L-M-L ∆Elin L-M-L ∆Elin Co(NH3)2– 180 Ni(NH3)2 180 Cu(NH3)2+ 180 Co(PH3)2– 132 6 Ni(PH3)2 180 Cu(PH3)2+ 180 Co(CO)2– 129 20 Ni(CO)2 145 2 Cu(CO)2+ 180 Rh(NH3)2– 180 Pd(NH3)2 180 Ag(NH3)2+ 180 Rh(PH3)2– 141 2 Pd(PH3)2 180 Ag(PH3)2+ 180 Rh(CO)2– 131 10 Pd(CO)2 156 1 Ag(CO)2+ 180 Ir(NH3)2– 180 Pt(NH3)2 180 Au(NH3)2+ 180 Ir(PH3)2– 144 2 Pt(PH3)2 180 Au(PH3)2+ 180 Ir(CO)2– 134 13 Pt(CO)2 159 1 Au(CO)2+ 180

ChemistryOpen 2013, 2, 106

Non-Linear d10-ML2

L-M-L ∆Elin L-M-L ∆Elin L-M-L ∆Elin Co(NH3)2– 180 Ni(NH3)2 180 Cu(NH3)2+ 180 Co(PH3)2– 132 6 Ni(PH3)2 180 Cu(PH3)2+ 180 Co(CO)2– 129 20 Ni(CO)2 145 2 Cu(CO)2+ 180 Rh(NH3)2– 180 Pd(NH3)2 180 Ag(NH3)2+ 180 Rh(PH3)2– 141 2 Pd(PH3)2 180 Ag(PH3)2+ 180 Rh(CO)2– 131 10 Pd(CO)2 156 1 Ag(CO)2+ 180 Ir(NH3)2– 180 Pt(NH3)2 180 Au(NH3)2+ 180 Ir(PH3)2– 144 2 Pt(PH3)2 180 Au(PH3)2+ 180 Ir(CO)2– 134 13 Pt(CO)2 159 1 Au(CO)2+ 180

ChemistryOpen 2013, 2, 106

slide-8
SLIDE 8

Non-Linear d10-ML2

L-M-L ∆Elin L-M-L ∆Elin L-M-L ∆Elin Co(NH3)2– 180 Ni(NH3)2 180 Cu(NH3)2+ 180 Co(PH3)2– 132 6 Ni(PH3)2 180 Cu(PH3)2+ 180 Co(CO)2– 129 20 Ni(CO)2 145 2 Cu(CO)2+ 180 Rh(NH3)2– 180 Pd(NH3)2 180 Ag(NH3)2+ 180 Rh(PH3)2– 141 2 Pd(PH3)2 180 Ag(PH3)2+ 180 Rh(CO)2– 131 10 Pd(CO)2 156 1 Ag(CO)2+ 180 Ir(NH3)2– 180 Pt(NH3)2 180 Au(NH3)2+ 180 Ir(PH3)2– 144 2 Pt(PH3)2 180 Au(PH3)2+ 180 Ir(CO)2– 134 13 Pt(CO)2 159 1 Au(CO)2+ 180

better π-accepting ligand à smaller bite angle

Non-Linear d10-ML2

L-M-L ∆Elin L-M-L ∆Elin L-M-L ∆Elin Co(NH3)2– 180 Ni(NH3)2 180 Cu(NH3)2+ 180 Co(PH3)2– 132 6 Ni(PH3)2 180 Cu(PH3)2+ 180 Co(CO)2– 129 20 Ni(CO)2 145 2 Cu(CO)2+ 180 Rh(NH3)2– 180 Pd(NH3)2 180 Ag(NH3)2+ 180 Rh(PH3)2– 141 2 Pd(PH3)2 180 Ag(PH3)2+ 180 Rh(CO)2– 131 10 Pd(CO)2 156 1 Ag(CO)2+ 180 Ir(NH3)2– 180 Pt(NH3)2 180 Au(NH3)2+ 180 Ir(PH3)2– 144 2 Pt(PH3)2 180 Au(PH3)2+ 180 Ir(CO)2– 134 13 Pt(CO)2 159 1 Au(CO)2+ 180

better π-backdonating metal à smaller bite angle

slide-9
SLIDE 9

ML–L Bonding Analysis

bending provides access for π* to fresh d electrons

"dπ" π∗ "dδ" π∗ Pd OC CO CO Pd OC 180º "π∗" "s" "dσ" "dδ" "dπ" "σ" "π" π∗ π σ "dπ" π∗ "dπ" π∗ Pd OC CO Pd OC 90º "π∗" C O "s" "dσ" "dδ" "dπ" "σ" "π" π∗ π σ

weak strong

ChemistryOpen 2013, 2, 106

Application to C–H Activation

design principles smaller bite à less cat. strain higher d à more stab. int.

  • ChemistryOpen. 2013, 2, 106

WIRES Comput. Mol. Sci. 2015, 5, 324

slide-10
SLIDE 10

Bite-Angle Flexibility:

“it is not about the angle”

47

Steric Attraction !

  • Crank up steric bulk Pd(PR3)2
  • Since Pd(PH3)2 is linear, all are... or not ??
  • R = H:

Yes

  • R = Me: Yes
  • R = iPr: Yes
  • R = tBu: Yes
  • R = Cy: No

ACS Catalysis 2015, 5, 5766 WIRES Comput. Mol. Sci. 2015, 5, 324

slide-11
SLIDE 11

Steric Attraction !

big surfaces stick together through Van der Waals forces “Anisotropic Bulk” + Room = Steric Attraction

Bite-Angle Flexibility

  • Energy profiles for bending Pd(PR3)2

Dispersion pulls minimum to 148° ... ... 132° for Pd(PPh3)2 !

slide-12
SLIDE 12

Application to C–H Activation

More flexible bite angle à less activation strain The "right bulk" provides steric protection + low barrier

51

3 - Electronic Regimes

  • f Catalysts

52

slide-13
SLIDE 13

E

∆Estrain

Electronic Regimes

What causes the opposite trend?

∆E ∆Eint

d M CH4 *C–H

RhCO– → RhPH3

–

∆ε HOMO +0.6 eV E

≠

–3.4 kcal/mol ! AgCO+ → AgPH3

+

∆ε HOMO +1.7 eV E

≠

+9 kcal/mol !

ASM and MO work perfectly è rational design, but...

  • Chem. Asian J. 2015, 10, 2272; WIRES Comput. Mol. Sci. 2015, 5, 324

Electronic Regimes

Same electronic configuration, yet opposite effect on barrier: Change of electronic REGIME from d-regime to s-regime

d M CH4

d-regime

*C–H s

C–H

catalyst tuning s

C–H

M CH4

s-regime

*C–H d catalyst tuning

  • Chem. Asian J. 2015, 10, 2272; WIRES Comput. Mol. Sci. 2015, 5, 324
slide-14
SLIDE 14

Summary

  • Bite-angle effect on reactivity has steric origin...
  • What matters is: bending strain (or flexibility).
  • Opposite tuning behavior: d-regime or s-regime.

55

Take-Home Message

  • KS-MO & EDA : causal model of bonding mechanism
  • Activation Strain Model generalization to reactions
  • Physical Understanding

and Rational Design

56

∆E(z) = ∆Estrain(z) + ∆Eint (z)

E ζ

X + Y TS XY ∆E(ζ) ∆Estrain(ζ) ∆Eint(ζ)

slide-15
SLIDE 15

Further Reading

  • Reviews in Computational Chemistry; K. B. Lipkowitz, D. B. Boyd,

Eds.; Wiley-VCH: New York, 2000, Vol. 15, pp. 1-86

  • Nature Chem. 2010, 2, 417
  • Chem. Soc. Rev. 2014, 43, 4953
  • WIRES Comput. Mol. Sci. 2015, 5, 324
  • Angew. Chem. Int. Ed. 2017, 56, 10070 (!)

57