POSSIBLE OBSERVATION OF THE 3 A’ - 1 A’ ELECTRONIC TRANSITION OF THE METHYLENE PEROXY CRIEGEE INTERMEDIATE Neal D. Kline, Marc Coons, John Herbert and Terry A. Miller Laser 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 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, 6 th ed. John Wiley & Sons, Inc c. Criegee, R. Agnew. Chem., Int. Ed. Engl. 1975, 14, 745

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. 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, ~ ~

1 A’ 3 A’ 1A11A1 3A23A2 1 A’ 3 A’ 1A11A1 3A23A2 1. Harding, L. B. and Goddard III, W. A. J. Am. Chem. Soc. 1978, 100, Wadt, W. R. and Goddard III, W. A. J. Am. Chem. Soc. 1975, 97, Electronic Structure of Methylene Peroxy and Ozone

High resolution FT-IR spectrum of Wulf band confirms it is 3 A 2  1 A 1 with minor contributions from the 3 B 1 and 3 B 2 states. Obtained rotational constants and excited state geometry that proved to be most consistent with 3 A 2 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 Geometry b : O-O: Å OOO Angle: o 3 A 2 State Geometry a : O-O: Å OOO Angle: 98.9 o Wulf Band a

1 A’ 3 A’ 1A11A1 3A23A (78) cm -1 Orbital overlap is smaller in methylene peroxy than in ozone a,b !! ? 1. Harding, L. B. and Goddard III, W. A. J. Am. Chem. Soc. 1978, 100, Wadt, W. R. and Goddard III, W. A. J. Am. Chem. Soc. 1975, 97, Electronic Structure of Methylene Peroxy and Ozone

1 A’ 3 A’ ? Determining a Transition Energy Transition Energy calculated using EOM(2,3)-SF-CCSD a with CCSD(T)/aug-cc-pVTZ geometries Transition Energy for 3 A’- 1 A’: 7069 cm -1 (±400 cm -1 ) a. Krylov, A. I. Annu. Rev. Phys. Chem. 2008, 59, 433. 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 Intensity

τ abs σ Nlσ Nl + = cL)/( R1 - ( ) Principles of CRDS τ0τ0 c L )/ ( R1 - = A = L/cτ abs - L/cτ 0 L l R time Intensity A

Sirah dye laser nm Nd:YAG: 532 nm Raman cell (H 2, 300 psi) 2 nd Stokes: cm -1 Room Temperature Cavity Ringdown Setup 20 Hz ~600 mJ/pulse ~70-80 mJ/pulse ~1-2 mJ/pulse Photolysis: Excimer Laser KrF, 248 nm Highly Reflective Mirror ( %) Highly Reflective Mirror ( %)

Preparing the Molecule Photolyze diiodomethane at 248 nm, one iodine atom dissociates. CH 2 I radical reacts with oxygen to give CH 2 IOO. CH 2 IOO then dissociates I atom to give CH 2 OO. 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,

Iodine atom 2 P 1/2  2 P 3/2 Precursor Absorption Precursor Absorption H 2 O Contamination Experimental Spectrum cm -1

Assigning Carrier of the Spectrum There are two possible carriers that can be responsible for the spectrum: Our Data and Observations Used photolysis of CH 2 I 2 precursor followed by reaction with O 2 to generate spectrum Observing our spectrum under conditions of 150 torr total pressure (84.9 torr N 2, 0.1 torr CH 2 I 2, 65.0 torr O 2 ) Observed same temporal behavior of our spectrum as well Y. P. Lee’s Data and Observations a Used photolysis of CH 2 I 2 precursor followed by reaction with O 2 to generate spectrum Observed methylene peroxy signal under conditions of 94 torr total pressure (0.13 torr CH 2 I 2, 2.47 torr N 2, O 2 ) 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 Spectrum There are two possible carriers that can be responsible for the spectrum: Huang et. al claim that CH 2 IO 2 is stabilized by addition of excess O 2 to the reaction a 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 CH 2 I 2 precursor a. Huang, H.; Eskola, A. and Taatjes, C. A. J. Phys. Chem. Lett. 2012, 3, 3399.

Assigning Carrier of the Spectrum There are two possible carriers that can be responsible for the spectrum: 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 O 2 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= kcal/mole 355 nm=80.54 kcal/mole kcal/mol 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, 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 3 A’- 1 A’ transition. Study the A-X transition of methylene peroxy. Obtain rotationally resolved spectrum of methylene peroxy. ~~

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 StateC-O Bond Length COO Bond Angle O-O Bond Length OOCH Dihedral Angle 3A’ 180 1A’ 180 Geometrical Parameters

1 A’ 3 A’ ? 1. Harding, L. B. and Goddard III, W. A. J. Am. Chem. Soc. 1978, 100, Wadt, W. R. and Goddard III, W. A. J. Am. Chem. Soc. 1975, 97, Determining a Transition Energy Transition Energy for 3 A’- 1 A’: cm -1 (±400 cm -1 ) Transition Energy calculated using c EOM(2,3)-SF-CCSD with CCSD(T)/aug-cc-pVTZ geometries c. Krylov, A. I. Annu. Rev. Phys. Chem. 2008, 59, 433. 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 perturbative Triples correction 3 is talking about active space Ideally have infinite basis set CAS reduces infinite down to more manageable calculation

Electronic Structure of Criegee Intermediate 1 A’ 4π (planar) 3 A’ 4π (planar) 1 A’’ 3π 3 A’’ 3π 1 A’‘ 5π 3 A’’ 5π 1 A’ 4π (perp) 3 A’ 4π (perp) 1 A’ 4π (planar) 3 A’ 4π (planar) 1 A’’ 3π 3 A’’ 3π 1 A’’ 5π 3 A’’ 5π 1 A’ 4π (perp) 3 A’ 4π (perp) C=1s 2 2s 2 2p 2 O=1s 2 2s 2 2p 4 Energy

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

1 1 A 1 3A23A2 3B23B2 3B13B1 1A21A2 1B11B1 1A11A1 1B21B Hartley Huggins Chappuis Wulf? Ground State Hartley Huggins Chappuis Wulf Energy Electronic Spectroscopy of Ozone

What is the Wulf Band? Wulf is 1 A 2  1 A 1 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 3 A 2  1 A 1 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).