POSSIBLE OBSERVATION OF THE 3A’-1A’ ELECTRONIC

TRANSITION OF THE METHYLENE PEROXY CRIEGEE

INTERMEDIATE

Neal D. Kline, Marc Coons, John Herbert and Terry A. MillerLaser Spectroscopy Facility The Ohio State University

RI11

Motivation for Study of Criegee Intermediates

• First proposed by Rudolf Criegee in 1949 as intermediate in ozonylsis of alkenes.

• Formed in the atmosphere and utilized heavily in organic chemistry to functionalize double bonds

C C

H

H

H

H

O

O

O

H2C CH2

OO

O

+

C

O

H H

C

HH

O

O

+

a. Criegee, R. and Wenner, G. Chem. Ber., 1949, 9, 564.b. Smith, M. B. and March, J. March‘s Advanced Organic Chemistry: Reactions and Mechanisms, and Structure, 6th ed. John Wiley & Sons, Inc. 2007.

H3C

H CH3

CH3

O3

CH2Cl2C C

H3C

H

O O

CH3

CH3

C

O

H3C CH3

+C

CH3H

O

O

O

C C

H3C

H

O O

CH3

CH3

O

Oxidative orReductive Workup

AlcoholsKetonesAldehydesAcids

c. Criegee, R. Agnew. Chem., Int. Ed. Engl. 1975, 14, 745

Literature Review on Criegee Intermediates

Literature Review on Criegee Intermediates

Current Study on Methylene Peroxy

• Planned to investigate the A-X transition predicted to be ~20,000 cm-1.

• When conducting literature search discovered there are similarities in electronic structure between methylene peroxy and ozone.

CO

O

H

H

OO

O

a. Lee, E. P. F.; Mok, D. K. W.; Shallcross, D. E.; Percival, C. J.; Osborn, D. L.; Taatjes, C. A. and Dyke, J. M. Chem. Eur. J. 2012, 18, 12411-12423.

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1A’ 3A’ 1A13A2

1A’

3A’

1A1

3A2

1. Harding, L. B. and Goddard III, W. A. J. Am. Chem. Soc. 1978, 100, 7180-7188.2. Wadt, W. R. and Goddard III, W. A. J. Am. Chem. Soc. 1975, 97, 3004-3021.

Electronic Structure of Methylene Peroxy and Ozone

H

H

C

O

O

H

H

O

O

O

High resolution FT-IR spectrum of Wulf band confirms it is 3A21A1 with minor contributions from the 3B1 and 3B2 states.

Obtained rotational constants and excited state geometry that provedto be most consistent with 3A2 state.

a. Bouvier, A. J.; Inard, D.; Veyret, V.; Bussery, B.; Bacis, R.; Churassy, S.; Brion, J.; Malicet, J; Judge, R. H. J. Mol. Spec. 190, 189 (1998).b. Tyuterev, V. G.; Tashkun, S.; Jensen, P.; Barbe, A.; Cours, T. J. Mol. Spec. 198, 57 (1999).

Ground State Geometryb:O-O: 1.27276 ÅOOO Angle: 116.75o

3A2 State Geometrya:O-O: 1.345 ÅOOO Angle: 98.9o

Wulf Banda

1A’

3A’

1A1

3A2

9553.021 (78) cm-1

Orbital overlap is smaller in methylene peroxy than in ozonea,b!!

?

1. Harding, L. B. and Goddard III, W. A. J. Am. Chem. Soc. 1978, 100, 7180-7188.2. Wadt, W. R. and Goddard III, W. A. J. Am. Chem. Soc. 1975, 97, 3004-3021.

Electronic Structure of Methylene Peroxy and Ozone

H

H

C

O

O

H

H

O

O

O

1A’

3A’

?

Determining a Transition Energy

Transition Energy calculated using EOM(2,3)-SF-CCSDa with CCSD(T)/aug-cc-pVTZ geometries

Transition Energy for 3A’-1A’: 7069 cm-1 (±400 cm-1)

a. Krylov, A. I. Annu. Rev. Phys. Chem. 2008, 59, 433.

C

O

O

H

H• Single determinant methods (HF,

DFT) will not work for excited triplet state.

• Need to use methods that incorporate determinants of different excitations. e.g. CASSCF, MRCI, MRCC

Already set up to work in this region!

Principles of CRDS

time

Inte

nsity

τabs

σ Nl+= cL )/(

R1 -( )

Principles of CRDS

τ0

cL )/(R1 -

=

A = L/cτabs - L/cτ0

L

l

R

time

Inte

nsity

A

Sirah dye laser570-705 nm

Nd:YAG: 532 nm

Raman cell (H2, 300 psi)

2nd Stokes:6000-9000 cm-1

Room Temperature Cavity Ringdown Setup

20 Hz~600 mJ/pulse

~70-80mJ/pulse

~1-2mJ/pulse

Photolysis:Excimer LaserKrF, 248 nm

HighlyReflective

Mirror(99.995 %)

HighlyReflective

Mirror(99.995 %)

Preparing the Molecule

• Photolyze diiodomethane at 248 nm, one iodine atom dissociates. CH2I radical reacts with oxygen to give CH2IOO. CH2IOO then dissociates I atom to give CH2OO.

a. Lee, E. P. F.; Mok, D. K. W.; Shallcross, D. E.; Percival, C. J.; Osborn, D. L.; Taatjes, C. A. and Dyke, J. M. Chem. Eur. J. 2012, 18, 12411-12423.

C

HI

HIH

248 nmC

H

HI

+ I

CH2

O

OO2

+ 2ICH2IOO

Wavenumber

7000 7500 8000 8500 9000

pp

m/p

ass

0

5

10

15

20

Iodine atom2P1/22P3/2

Precursor Absorption

Precursor Absorption

H2OContamination

Experimental Spectrum

+

+

+

+

+

+

+

+

+

+ + +

+

++

+

7069 cm-1

Assigning Carrier of the Spectrum

There are two possible carriers that can be responsible for the spectrum:

C

O

O

H HC

O

H HI

O

Our Data and Observations

• Used photolysis of CH2I2 precursor followed by reaction with O2 to generate spectrum

• Observing our spectrum under conditions of 150 torr total pressure (84.9 torr N2, 0.1 torr CH2I2, 65.0 torr O2)

• Observed same temporal behavior of our spectrum as well

Y. P. Lee’s Data and Observationsa

• Used photolysis of CH2I2 precursor followed by reaction with O2 to generate spectrum

• Observed methylene peroxy signal under conditions of 94 torr total pressure (0.13 torr CH2I2, 2.47 torr N2, 91.40 O2)

• Observed a ~50μs lifetime of absorption bands attributed to methyelene peroxy

a. Su, Y.; Huang, Y.; Witek, H. A. and Lee, Y. P. Science 2013, 340, 174.

Assigning Carrier of the SpectrumThere are two possible carriers that can be responsible for the spectrum:

C

O

O

H HC

O

H HI

O

• Huang et. al claim that CH2IO2 is stabilized by addition of excess O2 to the reactiona

• They observe a decrease in the amount of I atom produced, correlate observation to decrease in amount of methylene peroxy produced

• Performed experiment using 355 nm photolysis of CH2I2 precursor

a. Huang, H.; Eskola, A. and Taatjes, C. A. J. Phys. Chem. Lett. 2012, 3, 3399.

C

HI

HIH

355 nmC

H

HI

+ I

CH2

O

OO2

+ 2ICH2IOO ?

Iodine Atom Intensity and Criegee Intermediate Signal vs. O2 Pressure

Constant CH2I2 Pressure:0.10 torr

Constant Mirror Purge, Window Purge Pressure, Backing N2 (84.9 torr)

Additional Pressure of O2 Added0 10 20 30 40 50 60 70

pp

m/p

ass

0

10

20

30

40

50

60

70

80

Iodine Atom Signal as Function of O2 Pressure

Spectral Signal as Function of O2 Pressure

Assigning Carrier of the Spectrum

There are two possible carriers that can be responsible for the spectrum:

C

O

O

H HC

O

H HI

O

Y. P. Lee’s Data and Observations

• Through private communication with Y. P. Lee, they assert that using 248 nm photolysis addition of excess amounts of O2 does not affect yield of methylene peroxy.

• However, using 355 nm photolysis, the yield decreased drastically.

• C-I bond strength:51.62 kcal/mole• 248 nm=115.29 kcal/mole• 355 nm=80.54 kcal/mole

-29.14 kcal/mol

-1.08 kcal/mol

a. Lee, E. P. F.; Mok, D. K. W.; Shallcross, D. E.; Percival, C. J.; Osborn, D. L.; Taatjes, C. A. and Dyke, J. M. Chem. Eur. J. 2012, 18, 12411-12423.b. Huang, H.; Eskola, A. and Taatjes, C. A. J. Phys. Chem. Lett. 2012, 3, 3399

Final Thoughts

Conclusions:

All experimental observations with respect to the chemistry are consistent with the carrier of the spectrum being the methylene peroxy Criegee intermediate.

Future works:

Finish experimental work and vibrationally analyze the spectrum and definitively assign as the 3A’-1A’ transition.

Study the A-X transition of methylene peroxy. Obtain rotationally resolved spectrum of methylene peroxy.

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Acknowledgments

• Prof. Terry Miller• Miller group:

• Funding: -US Department of Energy (DOE)

-Dr. Dmitry Melnik-Dr. Mourad Roudjane-Dr. Rabi Chhantyal-Pun-Terrance Codd-Meng Huang

Theoretical Analysis

-Energies calculated using G2 method-Oscillator strengths calculated using UCIS/6-31G* method

State C-O Bond

Length

COO Bond Angle

O-O Bond

Length

OOCH Dihedral

Angle

3A’ 1801A’ 180

Geometrical Parameters

1A’

3A’

?

1. Harding, L. B. and Goddard III, W. A. J. Am. Chem. Soc. 1978, 100, 7180-7188.2. Wadt, W. R. and Goddard III, W. A. J. Am. Chem. Soc. 1975, 97, 3004-3021.

Determining a Transition Energy

Transition Energy for 3A’-1A’: 7068.97 cm-1 (±400 cm-1)

Transition Energy calculated using cEOM(2,3)-SF-CCSD with CCSD(T)/aug-cc-pVTZ geometries

c. Krylov, A. I. Annu. Rev. Phys. Chem. 2008, 59, 433.

C

O

O

H

H

• Ground state is open shell singlet described well by single reference methods

• Single determinant methods will not work for excited triplet state: HF, DFT.

• Need to use methods that incorptorate determinants of different excitations. (CASSCF, MRCI, MRCC)2,3 means how many active orbitals

You have.Which orbitals you choose to use.2 is double excitations, then use a perturbativeTriples correction3 is talking about active space Ideally have infinite basis setCAS reduces infinite down to more manageable calculation

Criegee Spectrum and Franck Condon simulations

Wavenumber

6000 6500 7000 7500 8000 8500 9000

ppm

/pas

s

0

5

10

15

20

25

Criegee Intermediate (shifted +5 ppm)

Criegee Intermediate (Shifted +5 ppm)

Degree of OOCH dihedral angle0 100 200 300

Ene

rgy

(eV

)

0

1

2

3

4

5

Singlet 4 pi A' stateTriplet 4 pi A' state

Electronic Structure of Criegee Intermediate

H

H

C

O

O

H

H

H

H

H

H

H

H

1A’ 4π (planar) 3A’ 4π (planar)

1A’’ 3π 3A’’ 3π

1A’‘ 5π 3A’’ 5π

1A’ 4π (perp) 3A’ 4π (perp)

1A’ 4π (planar)

3A’ 4π (planar)

1A’’ 3π

3A’’ 3π

1A’’ 5π

3A’’ 5π

1A’ 4π (perp)

3A’ 4π (perp)

C=1s22s22p2

O=1s22s22p4

Energy

Theoretical Analysis

1. Krylov, A. I. Annu. Rev. Phys. Chem. 2008, 59, 433.

Ψ 𝑀 𝑠𝑠 ,𝑡 =𝑅𝑀 𝑠=−1Ψ 𝑀𝑠=+1

𝑡

𝑅𝑀 𝑠=−1≡𝑅𝑆𝐹=∑𝑖𝑠

𝑟 𝑖𝑎𝑎𝛽+𝑖𝛼+…

Wavenumber

7400 7600 7800 8000 8200 8400

ppm

/pas

s

0

5

10

15

20

1 1A1

3A2

3B2

3B1

1A2

1B1

1A1

1B2

1

1

1

1

1

2

1 Hartley

Huggins

Chappuis

Chappuis

Wulf?

Wulf?

Wulf ?

Ground State

Hartley

Huggins

Chappuis

Wulf

Energy

Electronic Spectroscopy of Ozone

What is the Wulf Band?

• Wulf is 1A21A1 • Anderson, S. M.; Morton, J.; Mauersberger, K. J. Chem. Phys. 93, 3826 (1990).• Anderson, S. M.; Maeder, J.; Mauersberger, K. J. Chem. Phys. 94, 6351 (1991).• Hay, P. J.; Dunning Jr., T. H.; Goddard III, W. A. J. Chem. Phys. 62, 3912 (1975).• Hay, P. J.; Dunning Jr., T. H. J. Chem. Phys. 67, 2290 (1977).

• Wulf is 3A21A1

• Minaev, B. F.; Kozlo, E. M. J. Struct. Chem. 38, 895 (1997).• Mineav, B.; Agren, H. Chem. Phys. Lett. 217, 531 (1994).• Braunstein, M.; Pack, R. T. J. Chem. Phys. 96, 6378 (1992).