Microwave spectrum of furfuryl alcohol

Roman A. Motiyenko, Manuel Goubet, Thérèse R. Huet, Laurent Margulès, Georges WlodarczakPhLAM Laboratory, University Lille 1, Villeneuve d’Ascq, France

Eugen A. AlekseevInstitute of Radio Astronomy of NASU, Kharkov, Ukraine

Motivation

Ribose

furfural

furfuryl alcohol

2-furoic acid

R. Motiyenko et al.JMS, vol. 240, pp. 93-

101JMS, vol. 244, pp. 9-

12

decomposition products:

Furfuryl alcohol

skew 1 (E=210 cm-1) skew 2 (E=700 cm-1) skew 3 (E=0 cm-1)

syn 1 (E=42 cm-1) syn 2 (E=409 cm-1)

K.M. Marstokk and H. Mollendal, Acta Chemica Scandinavica, vol. 48, pp. 25 – 31 (1994)

Microwave measurements in 26 – 39.5 GHz frequency range and ab initio calculations at MP2/6-31G* level

Previous study:

Experimental setupoFTMW spectrometer in Lille (4 – 20 GHz)oMicrowave spectrometer in Kharkov

(60 – 150 GHz, measurement precision: 0.01 MHz)oMicrowave spectrometer in Lille

(150 – 210 GHz, measurement precision: 0.02 MHz)

Computational details:oab initio calculations at MP2 level with:

•6-311++G(3df,2p) •aug-cc-pVTZ• cc-pVQZ basis sets

MWFT results• In pulsed jet MWFT experiments with Ne as a carrier gas skew 3 was the

only conformer observed. This can be explained by effective relaxation of skew 1 into skew 3 during supersonic expansion

• Calculated ab initio value of barrier height to OH torsion between skew 1 and skew 3 is 320 cm-1 and thus suggests the relaxation in jet with Ne (R.S.Ruoff, T.D.Klots, T. Emilsson and H.S. Gutowsky, J.Chem.Phys. vol. 93, pp. 3142 – 3150 (1990))

skew 1 skew 3

Conventional spectroscopy

J=25←24 aR0,1

Excited vibrational states should be also studied!

Ka=

Ka=

Excited vibrational states

skew 1 skew 3

ring–CH2OH torsion 81.0 68.5

ring–CH2OH bending 148.7 143.8

OH torsion 264.5 261.4

Low-frequency vibrations @MP2/aug-cc-pVTZ (cm-1)

Assignment strategy

skew 1: μa=1.6 D

skew 3: μa=1.5 D

J+11,J+1 ← J1,J

J+10,J+1 ← J0,J

J+10,J+1 ← J1,J

J+11,J+1 ← J0,J

μb=1.6 D

J=25←24

Summary of results

skew 3 skew 1

N σ (MHz) J max

Ka max N σ (MHz) J

maxKa

maxv=0 1421 0.011 64 33 1345 0.013 65 26vt=1 1233 0.014 63 28 1291 0.013 65 25vt=2 728 0.016 58 9 - -vt=3 855 0.015 61 21 - -vb=1 651 0.015 60 9 149 0.018 43 3vOH=1 603 0.017 60 14vt=1,vb=1 784 0.016 62 19vt=2,vb=1 425 0.017 51 8

skew 1 vt=1

Old New

A (MHz) 6967.474(48) 6965.32266(22)

B (MHz) 1931.794(11) 1932.570317(41)

C (MHz) 1660.902(10) 1660.030379(44)

Ab initio calculations

Skew 1 Skew 3A

(MHz)B

(MHz)C

(MHz)a

(Deb.)b

(Deb.)c

(Deb.)A

(MHz)B

(MHz)C

(MHz)a

(Deb.)b

(Deb.)c

(Deb.)MP2/

6-311++G(3df,2p) 6965.0 1942.8 1674.9 -1.55 1.62 0.10 6975.5 1955.1 1671.4 1.50 -0.23 0.67MP2/

aug-cc-pVTZ 6946.8 1937.5 1670.6 -1.57 1.60 0.08 6957.3 1950.1 1667.1 1.52 -0.20 0.67MP2/

cc-pVQZ 6988.5 1944.6 1676.6 -1.51 1.56 0.13 6998.7 1957.6 1672.5 1.47 -0.25 0.64Exp. 6967.0 1931.1 1660.7 6979.0 1950.4 1657.7

Energies calculated using MP2/aug-cc-pVTZ and G3 methods (cm-1)

Rotational constants and dipole moments

skew 3 skew 1 (MP2)

skew 1 (G3)

syn 1 (MP2)

Transition state (skew1-skew3)

D1 D3

E 0.0 45.5 346 297 342

E-ZPE 0.0 55.9 112 157 213

Perturbations

Ka=9

Ka=9

50

100

150

200

250

E over ZPE (cm-

1 )

vt=1

vt=2vb=1

vt=3vt=1, vb=1

Ka=21

Ka=19

vOH=1 Ka=14vt=4vt=2, vb=1 vb=2

Ka=8

Ka=9

Ka=17

v=0

vt=1

vb=1vt=2

up to Ka=3

v=0skew 3skew 1

from previous study:ΔE=125(33) cm-1

New software

Acknowledgements

•Dr. Jean Demaison•Dr. Vadim Ilyushin•INTAS foundation (YSF ref. n0. 06-1000014-

5984)