mm_vib_suppmat. 24KB Jun 05 2011 09:30:46 PM

Supplementary Section

Vibrational Spectra of the larger acyl halides. While the MM3 force field can
easily calculate the vibrational frequencies of the n-butyryl halides, 2-methylpropionyl
halides, 2,2-dimethyl-propionyl halides, and even much larger acyl halides, no complete
experimental assignments of the vibrational frequencies for these compounds have been
found except for 2-methylpropionyl fluoridei and chloride.ii The vibrational frequencies
for these compounds are given in Table S1.

For 2-methylpropionyl fluoride, our

calculated

Table S1

frequencies gave rms errors of 24 cm-1 and 35 cm-1 for the gauche and syn isomers,
respectively, when compared with the gas phase IR data.19

For 2-methylpropionyl

chloride, the corresponding rms errors were 29 cm-1 and 37 cm-1, respectively, when

compared with the liquid phase Raman data.20
One of possible set of experimental data to be compared with our results were the
far-IR (30 cm-1 - 400 cm-1 ) spectra of several acyl halides. These frequencies for the 2,2dimethyl-propionyl halides are presented in Table S2. The rms deviations of our

Table S2

1

calculated vibrational frequencies for fluoride and chloride were 15 cm-1 and 23 cm-1,
respectively, compared with an experimental IR study.iii

2

Table S1. Fundamental vibrational frequencies (cm-1) of 2-methylpropionyl fluoride and
2-methylpropionyl chloride

(a) 2-methylpropionyl fluoride
assignment

symm.

gauche syn
A
A”
A
A”
A
A’
A
A’
A
A’
A
A’
A
A”
A
A’
A
A’
A

A”
A
A’
A
A”
A
A’
A
A”
A
A’
A
A”
A
A’
A
A’
A
A”
A

A’
A
A”
A
A”
A
A’
A
A’
A
A”
A
A’
A
A’
A
A’
A
A’
A

A”
A
A’
A
A”
A
A”

Raman(gas)a
gauche syn
2994 2994
2990 2990
2983 2983
2959 2959
2944 2944
2927 2927
2894 2894
1856 1856
1478 1478
1470 1470

1460 1460
1455 1455
1447 1447
1399 1399
1346 1346
1298 1298
1185 1185
1123 1123
1108 1108
1080 1080
966 966
930 930
905 896
780 780
723 723
597 597
486 523
352 352
301 301
238 238

223 223
210 210
54
54

Ab initioa,b
gauche syn
3303 3294
3275 3271
3286 3311
3283 3273
3228 3284
3218 3214
3213 3211
2038 2042
1682 1686
1663 1664
1673 1673
1659 1659
1596 1591

1575 1568
1506 1490
1450 1466
1281 1313
1253 1163
1217 1206
1329 1368
1063 1063
1054 1046
960 950
847 836
784 825
642 661
522 560
388 367
339 293
268 271
251 266
235 237
74

75

MM3
gauche syn
2990 2990
2987 2987
2991 2994
2989 2989
2952 2989
2897 2896
2894 2896
1878 1883
1476 1468
1469 1465
1466 1464
1460 1459
1434 1425
1444 1442
1388 1362
1348 1349

1219 1282
1075 1083
1092 1083
1057 1036
969 971
943 940
880 886
776 726
672 653
575 669
476 487
369 335
319 290
267 271
235 226
213 210
57
43

MM3 - IRa

gauche syn
-4
-4
-3
-3
8
11
30
30
8
45
-30
-31
0
2
22
27
-2
-10
-1
-5
6
4
5
4
-13
-22
45
43
42
16
50
51
34
97
-48
-40
-16
-25
-23
-44
3
5
13
10
-25
-10
-4
-54
-51
-70
-22
72
-10
-36
17
-17
18
-11
29
33
12
3
3
0
3
-11
24
35

CH3 str(as)
CH3 str(as)
CH3 str(as)
CH3 str(as)
α-CH str
CH3 str(s)
CH3 str(s)
C=O str
CH3 def(as)
CH3 def(as)
CH3 def(as)
CH3 def(s)
CH3 def(s)
CH3 def(s)
α-CH bend
α-CH bend
CH3 rock
CH3 rock
C-C str
C-F str
CH3 rock
CH3 rock
C-C str
C-C str
O=C-F wag
O=C-F def
O=C-F rock
C-C-C def
C-C-C wag
C-C-C twist
CH3 torsion
CH3 torsion
torsion(as)
rms deviation
a)Taken from reference 40.
b)Calculated at the RHF/6-31G* level, using Gaussian 90 program, in this work, and listed without
scaling.

3

(b) 2-methylpropionyl chloride
assignment

symm.
gauche syn
A
A”
A
A”
A
A’
A
A’
A
A’
A
A’
A
A”
A
A’
A
A’
A
A”
A
A’
A
A”
A
A’
A
A”
A
A’
A
A”
A
A’
A
A’
A
A”
A
A”
A
A”
A
A’
A
A’
A
A’
A
A”
A
A’
A
A’
A
A’
A
A’
A
A”
A
A’
A
A”
A
A”

Raman(liq.)a
gauche syn
3005b 3005b
2985
2985
2980b 2980b
2945
2945
2928
2928
2914
2914
2878
2878
1810
1810
1480b 1480b
1473b 1473b
1460
1460
1451
1451
1441b 1445b
1382b 1382b
1322
1322
1287
1287
1173
1173
1111
1111
1096
1096
966
966
940
940
932
932
847
847
687
563
642
642
437
437
416
416
320
337
310b
310b
224
224
228b
228b
222b
222b
110b
110b

CH3 str(as)
CH3 str(as)
CH3 str(as)
CH3 str(as)
α-CH str
CH3 str(s)
CH3 str(s)
C=O str
CH3 def(as)
CH3 def(as)
CH3 def(as)
CH3 def(s)
CH3 def(s)
CH3 def(s)
α-CH bend
α-CH bend
CH3 rock
CH3 rock
C-C str
CH3 rock
CH3 rock
C-C str
C-C str
C-Cl str
O=C-Cl wag
O=C-Cl def
O=C-Cl rock
C-C-C def
C-C-C wag
C-C-C twist
CH3 torsion
CH3 torsion
torsion(as)
rms deviation
a)Taken from reference 41 b).
b)Assigned from the solid phase Raman spectrum.

5

MM3
gauche syn
2990
2994
2987
2987
2993
2995
2989
2989
2963
2975
2898
2897
2895
2898
1810
1814
1475
1472
1467
1472
1463
1462
1459
1459
1428
1428
1441
1443
1376
1365
1340
1360
1134
1186
1065
1069
1078
1084
968
971
939
939
992
980
853
859
690
580
590
601
459
545
414
420
321
320
298
236
236
262
236
225
207
209
56
56

MM3 - IRa
gauche syn
-15
-11
2
2
13
15
44
44
35
47
-16
-17
17
20
0
4
-5
-8
-6
-1
3
2
8
8
-13
-27
59
63
54
43
53
73
-39
13
-46
-42
-18
-12
2
5
-1
-1
60
48
6
12
3
17
-52
-41
22
108
-2
-4
1
-17
-12
-74
12
38
8
-3
-15
-13
-54
-54
29
37

Table S2. Vibrational frequencies (in cm-1) of 2,2-dimethylpropionyl fluoride, chloride,
and bromide in the far-IR region (30 - 400 cm-1)

(CH3)3CCOF

(CH3)3CCOCl

IR(gas)a

IR(gas)b

MM3-IRa

(CH3)3CCOBr

assignment
symm.
MM3
MM3
Ab initioc MM3
skeletal bend
A’
354
346
-8
352
337
-15
317
321
skeletal bend
A”
320d
286
-34
321d
286
-35
315
286
skeletal bend
A’
272
271
-1
231e
241
10
279
240
CH3 torsion
A’
242
242
0
235
234
-1
208
192
CH3 torsion
A”
231
250
18
204
251
47
266
250
CH3 torsion
A”
210e
216
6
207e
213
6
224
211
torsion(as)
A”
53
52
-1
50
56
6
64
61
rms deviation
15
23
a),b)Taken from reference 34.
c)Calculated at the RHF/3-21G* level, using Gaussian 94 program, in this work, and listed without
scaling.
d)Assigned from the solid phase Raman spectrum.
e)Assigned from the solid phase IR spectrum.

6

MM3-IRb

i

J. R. Durig, G. A. Guirgis, W. E. Brewer, and G. Baranovic, J. Phys. Chem., 96, 7547

(1992).
ii

G. A. Guirgis, H. V. Phan, and J. R. Durig, J. Mol. Struct., 266, 265 (1992).

iii

J. R. Durig, R. Kenton, H. V. Phan, and T. S. Little, J. Mol. Struct., 247, 237 (1991).

7