61st OSU International Symposium on Molecular Spectroscopy RI1261st OSU International Symposium on Molecular Spectroscopy RI12

Rotational spectrum, electric dipole moment Rotational spectrum, electric dipole moment and structure of salicyl aldehydeand structure of salicyl aldehyde

Zbigniew Kisiel, Orest Dorosh, Lech Pszczółkowski

Institute of Physics, Polish Academy of SciencesWarszawa, Poland

Marianna Kańska, Tadeusz M. Krygowski

Department of Chemistry, University of Warsaw, Warszawa, Poland

Desyatnyk et. al.. Desyatnyk et. al.. PCCPPCCP 77, , 17081708 (200 (20055))Desyatnyk et. al.. Desyatnyk et. al.. PCCPPCCP 77, , 17081708 (200 (20055))

Benzaldehyde:Benzaldehyde:Anisole:Anisole:

1.76(1) Å

Jones and Curl: Jones and Curl: J.Mol.Spectrosc. 42, 65 (1972)

“…Structure of the Hydrogen Bond”

Only a , R-type transitions measured at

26.5-40 GHz + rigid rotor analysis

Some background on salicyl aldehyde:Some background on salicyl aldehyde:

MMW spectrum MMW spectrum (Warsaw broadband spectrometer):(Warsaw broadband spectrometer):

analysed to determine accurate spectroscopic constants of the parent isotomers

Ab initio:Ab initio:

calculated force field scaled using experimental values for the parent and used to calculate quartic for the isotopomers

FTMW spectrum FTMW spectrum (Warsaw jet spectrometer):(Warsaw jet spectrometer):

ground state measurements made on at least 7 selected transitions to determine A, B, C

Molecular structure:Molecular structure:

least-squares rm geometry fitted with program STRFIT from the

websiteSTRFITSTRFITSTRFITSTRFIT

Steps in this investigation:Steps in this investigation:

AABS = Assignment and Analysis of Broadband Spectra

AABS = Assignment and Analysis of Broadband Spectra

bRaR

bR + aR

GAMESSGAMESSGAMESSGAMESS FCONVFCONVFCONVFCONV VIBCAVIBCAVIBCAVIBCA

}1.5 %

541 transitions in fit

Deviation of fit = 51.5 kHz

aR, bR, aQ, bQ transitions measured

Results for the ground state of parent salicyl aldehydeResults for the ground state of parent salicyl aldehyde

All 15 singly substituted isotopomers:

Heavy nuclei in natural abundance

DO substitution with D2O, other D from three different reactions to substitute at C7 (DCO), C3+C5, and C4+C6

}

Number Type

1 parent

2 18O7 13C6 d1

5 d2

1 d3

1 d4

1 d5

2 13C,D_____

26

} Additional isotopomers obtained as a by-product or by deuterating other samples further with D2O

Isotopomers used for structure determinationIsotopomers used for structure determination

Desyatnyk et. al.. Desyatnyk et. al.. PCCPPCCP 77, , 17081708 (200 (20055))Desyatnyk et. al.. Desyatnyk et. al.. PCCPPCCP 77, , 17081708 (200 (20055))

Anisole:100% Ar

100% He

Use of He/Ar gas mixture to increase line intensityUse of He/Ar gas mixture to increase line intensity

Ground state

Measured

Equilibrium

Calculated

Vibration-rotation contribution:

= harmonic + anharmonic

, , = = aa, , bb, , cc

Moments of inertiaMoments of inertia

as/Å bs/Å

C1 0.271(6) -0.557(3) C2 0.090 i 0.818(2) C3 -1.295(1) 1.271(1) C4 -2.335(1) 0.345(4) C5 -2.086(1) -1.031(2) C6 -0.769(2) -1.476(1) C7 1.662(1) -1.057(1) O2 2.658(1) -0.333(5) O1 1.014(2) 1.734(1) H2 1.874(1) 1.260(1) H3 -1.483(1) 2.337(1) H4 -3.356(1) 0.706(2) H5 -2.907(1) -1.733(1) H6 -0.541(3) -2.539(1) H7 1.781(1) -2.151(1)

Kraitchman coordinates for salicyl aldehydeKraitchman coordinates for salicyl aldehyde

rm(1) c

rm(2) c d

J.Mol.Spectrosc. J.Mol.Spectrosc. 196196, 102 (1999), 102 (1999)

rm(L)

rm(1L) c

Watson’s modified Watson’s modified rrmm method method

STRFITSTRFITSTRFITSTRFIT = STRucture FITting program:

Flexible declaration using internal coordinates

Fitting to moments of inertia, provision for various degenerate coordinates

r0, rz, rm(1), rm

(2), rm(1L), rm

(2L) (many worked examples)

Any number of isotopomers, any combination of constants

Structural declaration the same as used by PMIFST allowing direct visualisation

PMIFSTPMIFSTPMIFSTPMIFST

http://info.ifpan.edu.pl/~kisiel/http://info.ifpan.edu.pl/~kisiel/prospe.htmprospe.htm

http://info.ifpan.edu.pl/~kisiel/http://info.ifpan.edu.pl/~kisiel/prospe.htmprospe.htm

Fit to 78 moments of inertia

Deviation of fit = 0.0037 u Å2

ca=0.067(11), cb=0.079(12), cc=0.099(13) u1/2Å [ H=0.01Å]

1.783(2) Å

145.1(1)o

The The rrmm(1L)(1L) geometry of salicyl aldehyde geometry of salicyl aldehyde

electron electron diffractiondiffraction

Ab initioAb initio, 6-, 6-31G(d,p)31G(d,p)

this workthis work previous previous rotationalrotational

1.783(2) Å

1.76(1) Å

1.74(2) Å

2.9(3)o

0.6(2)o

0.5(10)o

1.3(9)o

DFT -0.6o

MP2 0.5o

DFT 1.3o

MP2 2.2o

6o

OO=2.645 Å

OO=2.65 Å

Electrodes: 28x28 cm, 27cm apart

Electric field: 500 V/cm

IFPAN Stark electrodes for uniform field distributionIFPAN Stark electrodes for uniform field distribution

KisielKisiel et. al.. et. al.. CPLCPL 325325, 523 (2000), 523 (2000)KisielKisiel et. al.. et. al.. CPLCPL 325325, 523 (2000), 523 (2000)

Stark measurements for salicyl aldehydeStark measurements for salicyl aldehyde

a = 2.343(2) b = 1.811(1)

tot = 2.961(2)

a = 2.906(2) b = 1.188(1)

tot = 3.140(2)

Dipole moment comparison between benzaldehyde and Dipole moment comparison between benzaldehyde and salicyl aldehydesalicyl aldehyde

32.4o56.9o

Resolved deuterium hyperfine structure in DO-salicyl Resolved deuterium hyperfine structure in DO-salicyl aldehydealdehyde

Information on the intramolecular hydrogen bond ?