INFRARED SPECTRUM OF MATRIX-ISOLATED METHYLHYDROXYCARBENE INFRARED SPECTRUM OF MATRIX-ISOLATED...
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Transcript of INFRARED SPECTRUM OF MATRIX-ISOLATED METHYLHYDROXYCARBENE INFRARED SPECTRUM OF MATRIX-ISOLATED...
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