Vibrational assignment and force field for 2-fluoroethanol

Journal of Fluorine Chemistry, 6 (1975) 279 - 285 0 Elsevier Sequoia .%A., Lausanne - Printed in the Netherlands

279

Received: April 22, 1975

SHORT

COMMUNICATION

Vibrational

G.

Assignment

and Force

and DOUGLAS

GROWDER

of Chemistry

West

Texas

State

There

have

spectra

studies, C-O-H

University,

Buckley,

1370-1411

cm

frequency

-1

cm "

assignments Normal

be useful spectra The

of the infrared

value).

In the most

Wyn-Jones

recent the

in the

and Orville-

to a band

observed

differences

calculations

in an attempt

and to obtain

have

in

now been made

to learn more

a force

field

as an aid in the interpretation

of other

about

(I_) assumed

the CH2 wags

Other

U.S.A.

disagreement

and Yamamoto

this vibration

coordinate

modes

studies

(L-A>, with

79016.,

exist.

for 2-fluoroethanol the normal

Texas

whereas

(solution

Center

Canyon,

overlaps

region,

also

Research

of the bands.

Giguere,

(5) assigned

at 1206

computer

several

of some

bending

Thomas

and Killgore

of 2-fluoroethanol

the assignment

for 2-Fluoroethanol

TENNANT

Department

been

Field

about

that might

of vibrational

fluoroalcohols.

calculations

were

carried

and utilized

programs

out with

written

an IBM 360140

by Schachtschneider

280 (&,7)

for

the

vibrational

secular

refinement

of

frequencies

for

exist

in

(A,?)

and

The

the

C-H

were: c-o

=

the

of

gauche

=

the

The

the fit

the

the

the

other

O-H

= 0.971,

interbond

CCF

to

indicated.

planes

was

parameters

1.531,

angles

of

infrared

have

molecular =

be

assumed

previous

and

C-C

should

was

studies

CC0

the

calculated

treatment

molecule as

of

least-squares

references

(8)

and

all

solution

calculations,

etc.

between

60",

and

to

These

diffraction

1.091,

1.4511,

for

conformation,

angle be

G matrix,

and

observed.

electron

to

the

constants

problem,

azimuthal

assumed

force

details

redundancy

of

equation,

the

to

consulted the

calculation

were

C-F

used

=

1.39&,

assumed

to

be

tetrahedral.

Initial parameter taken

force

modified

from

the

64

and

butions

were 85

from

0.837

in

several

several

cm

ten

The

The

force

constant and

least-squares

were

between

observed

and

calculated

(lo),

for of

been

two

values,

using

and

the

made

calculated wavenumbers

calculated contri-

initial were

and

during

an

the

made

then which

final

average

values are

value

potential

In in

aid

fre-

guides,

adjusted.

resulting

to

changes

as were

an

were

were

negative

assigned manual

were

values

large

used

or

calculated

of

refined,

was

zero-order

refinements

observed

that

constructed

..I2matrices

constants

forty-four

were

A number

distributions

force

had

Lne

fluoride

because

low,

for field

except

which

FXO,

constants

ference

too

mdynelrad.

different

ethyl

reasonable -1

force

coordinates

interpretation.

of

energy

(T),

Symmetry

quencies

values

valence

ethanol

estimated. in

constant

run,

dif-

of

0.8

listed

in

cm

-1

.

281 TABLE

1

Observed and calculated coordinate descriptions

wavenumbers and approximate for 2-fluoroethanol

normal

Obs.a

Calc.

1459

1460

cH26(47),CH2w(17),CH2redundancY(17)

1453

cH26(68),CH2redundancy(2C)

1394

1394

cH2s(29),CH2tw(26),CH2w(22)

1368

1369

CH2tw(64),COH6(15)

1344

1344

CH2tw(55),CH2w(29)

1250

1249

CH2w(84),C-Cs(2.2)

1206

1206

COH6(67),CH2tw(19),CH2w(13)

1123

1123

c-Cs(34) ,CH2r(28),C-Fs(W

1087

1086

CH2r(49),C-Fs(17),CH2w(15)

1029

1030

C-Fs(46),CH2r(23),CH2w(13)

887

a86

C-Os(67),C-Cs(19),CH2r(ll)

a53

a53

CH2r(66),C-Fs(26)

508

508

cco6(57) ,CCF6(26),CH2r(10)

343

343

-OHr(90),CCF6(19)

300

296

CCFs(35),CCOs(31),-OHr(9)

1452

.

aObserved b

P.E.D.(%)b

values

taken

from refs.

4 and 5.

Abbreviations used are: 6 = deformation, w = wag, tw = twist, s = stretch, r = rock, 'c = torsion. Contributions to the potential energy of less than 10% are excluded, except for torsional coordinate.

Table

1, along

tribution matrix obtained

among

in terms

with

the approximate

the diagonal

elements

of the symmetry

for the force

potential

constants

energy

of the force

dis-

constant

coordinates.

The

are listed

in Table

final 2.

values

282 TABLE

2

Force

constants

Force Constant

for Z-fluoroethanol

Group

Coordinate(s) involved

Atom(s) common

Valuea

Stretch Kt

O-H

Kd

CH2

KS KR KX

O-H

7.479

C-H

4.811b

c-o

c-o

4.900b'C

c-c

c-c

4.600b'=

C-F

C-F

5.150b

-CH2

Stretch-stretch Fd

CH2-CH2

CH,

FRS

c-c-o

c-c,

c-o

F

C-C-F

C-C,

C-F

Hg

C-CH2-0

H-C-H

H:

C-CH2-F

H-C-H

C-O-H

C-O-H

0.759

C-CH2-0

C-C-H

O.JOJd

H' Y

C-CH2-F

C-C-H

0. 80gb

HE

C-CH2-0

O-C-H

O.JOOd

He

C-CH2-F

F-C-H

0.81Jb

HcI

c-c-o

c-c-o

1.182b

HE

C-C-F

C-C-F

1.012b

RX

CH

0.025b -0.013 0.143b

Bend

HO H

Y

283 TABLE

2

Force Constant

(continued)

Group

Coordinate(s) involved

Atom(s) common

Valuea

Stretch-bend F

CH2-CH2

C-C,

CCH

c-c

0.316d

c-c-o

c-c,

cc0

c-c

0.403b

C-C-F

C-C,

CCF

c-c

-0.144b

C-O-H

C-O,

COH

c-o

O.lOOb'C

CH2-0

C-O,

HCO

c-o

0.069

c-c-o

c-o,

cc0

c-o

0.61ab

CH2-F

C-F, HCF

C-F

0.500b*c

C-C-F

C-F,

CCF

C-F

0.360bsC

CCH,

CCH

c-c

-0.040d

CH2-0

HCO,

HCO

c-o

-0.070b'C

CH2-F

HCF,

HCF

C-F

-0.143b

C-CH2-0

CCH, HCO

C-H

0.000

F" YE

C-CH2-0

CCH, HCO

C

0.026

F' Y8 F" Y8

C-CH2-F

CCH, HCF

C-H

0.062

C-CH2-F

CCH, HCF

C

0.000

F

CF-C-;OH

CCF,

F

RY RU

FRB FS+ F F

SE SO

FX8 FXS Bend-bend F

Y

FE Fe F;e

2T

CH2

fg Y

CH2

ft Y

CH2

fg Yc

CH2

-CH2'

C-OH

0.041b

-CH2

HCC, CCH gauche

c-c

-CH2

HCC, CCH trans

c-c

0.008b

-c-o

HCC, CC0 gauche

c-c

-0.037b

-0.024

284 TABLE

2

(continued)

Force Constant

Atom(s) common

Coordinate(s) involved

Group

Valuea

ft Yo

CH2-C-O

HCC, CC0 trans

c-c

0.142d

fg YE

CH2-C-F

HCC, CCF gauche

c-c

-0.037b

ft y9

CH2-C-F

HCC, CCF trans

c-c

0.037b

fg UB

O-C-C-F

OCC, CCF gauche

c-c

0.077d

fg s+

CH2-O-H

HCO, COH gauche

c-o

0.093d

ft s@

CH2-O-H

HCO, COH trans

c-o

-0.117d

fg o$

C-C-O-H

CCO,

c-o

0.04gb

C-OH

c-o

COH gauche

Torsion

aStretching constants in b

0.053

constants are in units of are in units of mdyne/rad;

units

of

Constrained

mdyne to

mdyne/i; bending

stretch-bend constants are

I/(rad)2

transferred

values

'Estimated d

Adjusted

The

in

a prior

present

and

Orville-Thomas

the

C-O

which authors.

is

stretch

work (4) is

C-O

but

supports of

assigned

considerably The

calculation

lower

stretch

the to

the COH

was

in

the

assignment bending

the

than

not

band

the

assigned

of

final

Wyn-Jones

frequency. observed

assignments to

bands

run.

However, cm -1 ,

at

887

of

previous

at

880

cm

-1

285

in ethanol bend was 1218

(2) and 971 cm -l

assigned

cm-l

to bands

in n-propanol

i n n-propanol.

(9,111 at 1242

-1

cm

The COH

in ethanol

(2) and

(9_,u).

ACKNOWLEDGEMENT The

authors

for

financial

1

M. Kuhn, 170

2

3

5

7

10

11

2. Anal.

Chem.

and Ii. D. Mettee,

Chem.,

Sot. Japan,

Can.

J. Chem.,

42

326. and W. J. Orville-Thomas,

P. Buckley,

P. A. Giguere,

46

(1968)

19

(1963)

M. Igarashi (1956)

and D. Yamamoto,

Struct.,

Can.

J.

and R. G. Snyder,

Spectrochim.

117.

J. H. Schachtschneider, Nos.

J. Mol.

2917.

J. H. Schachtschneider

231-64

Shell

(1964)

and M. Yamaha,

Development

and 57-65 Bull.

Co. Tech.

(1965).

Chem.

Sot. Japan,

871.

G. Crowder

and D. Tennant,

G. A. Crowder (1973)

Foundation

1744.

79.

29 9

Bull.

1 (1967-68)

Rept., 8

and R. Mecke,

and H. Iwamura,

E. Wyn-Jones

Acta,

A. Welch

106.

P. J. Krueger

Chem., 6

to The Robert

of this work.

W. Luttke,

(1962)

(1964) 4

support

(1959)

M. Oki 35

are grateful

unpublished

and H. K. Mao,

J. Mol.

results. Struct.,

18

33.

K. Fukushima 26 (1968)

and B. J. Zwolinski,

368.

J. Mol.

Spectrosc.,