INFRARED SPECTRUM OF INFRARED SPECTRUM OF MATRIX-ISOLATED MATRIX-ISOLATED

METHYLHYDROXYCARBENE METHYLHYDROXYCARBENE

C. A. BAUMANN C. A. BAUMANN

Department of ChemistryDepartment of Chemistry

The University of ScrantonThe University of Scranton

Methylhydroxycarbene

trans cis triplet

Gas phase photochemistry of biacetyl

< 450 nm

Gas phase photochemistry of biacetyl

Difference spectra- 405 nm irradiation

Computational Details Computational Details

Gaussian 03WGaussian 03W

UB3LYP, UMP2, UMPW1KUB3LYP, UMP2, UMPW1K

6-311++G(2d,p)6-311++G(2d,p)

Scale factors: 0.963, 0.961, 0.943Scale factors: 0.963, 0.961, 0.943

aaGaussian 03, Revision C.02, Frisch, M. J. Gaussian 03, Revision C.02, Frisch, M. J. et al.et al. Gaussian, Inc., Wallingford CT, 2004; Gaussian, Inc., Wallingford CT, 2004; Becke, A. D. Becke, A. D. J. Chem. Phys.J. Chem. Phys. 19931993, , 9898, 5648; , 5648; Lee, C.; Yang, W.; Parr, R. G. Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. BPhys. Rev. B 19881988, , 3737, 785;, 785;

Møller, C.; Plesset, M. S. Møller, C.; Plesset, M. S. Phys. Rev.Phys. Rev. 19341934, , 4646, 618;, 618; Lynch, B. J.; Fast, P. L.; Harris, M.; Truhlar, D. G. Lynch, B. J.; Fast, P. L.; Harris, M.; Truhlar, D. G. J. Phys.J. Phys.Chem. A Chem. A 20002000, , 104104, 4811-4815., 4811-4815.

trans-CH3COH*CH2CO

cis-CH3COH*CH2CO

triplet-CH3COH*CH2CO

cis-CH3COH*CH2CO

CH3COH*CH2CO Vibrations

CD3COD*CD2CO Vibrations

-100

100

300

500E

ner

gy

(kJ/

mo

l)

= 405 nm

= 436 nm

Intramolecular Hydrogen Transfer

Acetyl-Acetyl Hydrogen Transfer

Apparent efficiencies for the production of ketene and MCA.

(nm) matrix CH2CO CD2CO H/D MCA MCA-d6 H/D

N2 3(2)×10-3 1.4(5)×10-4 21 3 (2) ×10-3 5(3)×10-4 6

O2 4(2) ×10-3 4(2) ×10-4 11 6(3) ×10-3 2.5(5) ×10-3 2

405 Ar 2(2) ×10-3 4(1) ×10-5 54 2(2) ×10-3 1.7(3) ×10-4 79

Kr 1.2(7)×10-3 7(3) ×10-6 176 2(1)×10-3 2(1)×10-5 82

Xe 9(5)×10-4 3(3) ×10-6 300 1.2(7) ×10-3 6(6) ×10-6 195

O2 4(2) ×10-4

436 N2 3(2) ×10-3 8(3) ×10-4

Ar 4(4) ×10-4 2(2) ×10-5 25 6(6)×10-5 7(7)×10-5 0.8

254N2 3(2) ×10-3 < 10-5

Ar 0.02(3) 0.006(6) 2 < 10-5 < 10-5

CH2CO

0.00010

0.00100

0.01000

100 1000 10000 100000

dilution factor

nitrogen

krypton

oxygen

argon

xenon

Concentration Dependence

CD2O

0.000001

0.000010

0.000100

0.001000

100 1000 10000

dilution factor

nitrogen

krypton

oxygen

argon

xenon

Concentration Dependence

Pulsed vs. Continuous Irradiation

70

pulsed

cw

405 nm337 nm

20

pulsed

cw

Pulsed plus Continuous Irradiation

Triplet-Triplet Absorption

Triplet-Triplet Absorption

Triplet-Triplet Absorption

Triplet-Triplet Absorption

ConclusionsConclusions

ciscis conformation, complexed with conformation, complexed with keteneketene

H/D isotope effectH/D isotope effect

Acetyl-acetyl H abstractionAcetyl-acetyl H abstraction

Triplet-triplet absorption-TTriplet-triplet absorption-T44

AcknowledgmentsAcknowledgments

Petroleum Research Fund of the Petroleum Research Fund of the American Chemical SocietyAmerican Chemical Society

National Science FoundationNational Science Foundation

Research CommitteeResearch Committee

Faculty Development BoardFaculty Development Board