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

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1

Supplementary Section

Vibrational Spectra of

t

he 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 fluoride

i

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

2,2-dimethyl-propionyl halides are presented in Table S2. The rms deviations of our

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calculated vibrational frequencies for fluoride and chloride were 15 cm

-1

and 23 cm

-1

,

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[image:3.612.91.531.195.670.2]

3

Table S1. Fundamental vibrational frequencies (cm

-1

) of 2-methylpropionyl fluoride and

2-methylpropionyl chloride

(a) 2-methylpropionyl fluoride

assignment symm. Raman(gas)a _{Ab initio}a,b _MM3 _{MM3 - IR}a

gauche syn gauche syn gauche syn gauche syn gauche syn

CH3 str(as) A A” 2994 2994 3303 3294 2990 2990 -4 -4

CH₃_str(as) A A” 2990 2990 3275 3271 2987 2987 -3 -3

CH₃ str(as) A A’ 2983 2983 3286 3311 2991 2994 8 11

CH₃_str(as) A A’ 2959 2959 3283 3273 2989 2989 30 30

α-CH str A A’ 2944 2944 3228 3284 2952 2989 8 45

CH₃_str(s) A A’ 2927 2927 3218 3214 2897 2896 -30 -31

CH₃_str(s) A A” 2894 2894 3213 3211 2894 2896 0 2

C=O str A A’ 1856 1856 2038 2042 1878 1883 22 27

CH₃_def(as) A A’ 1478 1478 1682 1686 1476 1468 -2 -10 CH3 def(as) A A” 1470 1470 1663 1664 1469 1465 -1 -5

CH₃_def(as) A A’ 1460 1460 1673 1673 1466 1464 6 4

CH₃_def(s) A A” 1455 1455 1659 1659 1460 1459 5 4

CH₃_def(s) A A’ 1447 1447 1596 1591 1434 1425 -13 -22

CH₃_def(s) A A” 1399 1399 1575 1568 1444 1442 45 43

α_{-CH bend} A A’ 1346 1346 1506 1490 1388 1362 42 16

α_{-CH bend} A A” 1298 1298 1450 1466 1348 1349 50 51

CH₃_rock A A’ 1185 1185 1281 1313 1219 1282 34 97

CH3 rock A A’ 1123 1123 1253 1163 1075 1083 -48 -40

C-C str A A” 1108 1108 1217 1206 1092 1083 -16 -25

C-F str A A’ 1080 1080 1329 1368 1057 1036 -23 -44

CH₃_rock A A” 966 966 1063 1063 969 971 3 5

CH₃_rock A A” 930 930 1054 1046 943 940 13 10

C-C str A A’ 905 896 960 950 880 886 -25 -10

C-C str A A’ 780 780 847 836 776 726 -4 -54

O=C-F wag A A” 723 723 784 825 672 653 -51 -70

O=C-F def A A’ 597 597 642 661 575 669 -22 72

O=C-F rock A A’ 486 523 522 560 476 487 -10 -36

C-C-C def A A’ 352 352 388 367 369 335 17 -17

C-C-C wag A A’ 301 301 339 293 319 290 18 -11

C-C-C twist A A” 238 238 268 271 267 271 29 33

CH₃ torsion A A’ 223 223 251 266 235 226 12 3

CH₃ torsion A A” 210 210 235 237 213 210 3 0

torsion(as) A A” 54 54 74 75 57 43 3 -11

rms deviation 24 35

a)Taken from reference 40.

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(b) 2-methylpropionyl chloride

assignment symm. Raman(liq.)a _MM3 _{MM3 - IR}a

gauche syn gauche syn gauche syn gauche syn

CH₃ str(as) A A” 3005b ₃₀₀₅b ₂₉₉₀ ₂₉₉₄ _-15 _-11

CH₃_str(as) A A” 2985 2985 2987 2987 2 2

CH₃ str(as) A A’ 2980b ₂₉₈₀b ₂₉₉₃ ₂₉₉₅ ₁₃ ₁₅

CH₃_str(as) A A’ 2945 2945 2989 2989 44 44

α-CH str A A’ 2928 2928 2963 2975 35 47

CH3 str(s) A A’ 2914 2914 2898 2897 -16 -17

CH₃_str(s) A A” 2878 2878 2895 2898 17 20

C=O str A A’ 1810 1810 1810 1814 0 4

CH₃_def(as) A A’ 1480b ₁₄₈₀b ₁₄₇₅ ₁₄₇₂ _-5 _-8

CH₃_def(as) A A” 1473b ₁₄₇₃b ₁₄₆₇ ₁₄₇₂ _-6 _-1

CH₃_def(as) A A’ 1460 1460 1463 1462 3 2

CH3 def(s) A A” 1451 1451 1459 1459 8 8

CH₃_def(s) A A’ 1441b ₁₄₄₅b ₁₄₂₈ ₁₄₂₈ _-13 _-27

CH₃_def(s) A A” 1382b ₁₃₈₂b ₁₄₄₁ ₁₄₄₃ ₅₉ ₆₃

α_{-CH bend} A A’ 1322 1322 1376 1365 54 43

α_{-CH bend} A A” 1287 1287 1340 1360 53 73

CH₃_rock A A’ 1173 1173 1134 1186 -39 13

CH₃_rock A A’ 1111 1111 1065 1069 -46 -42

C-C str A A” 1096 1096 1078 1084 -18 -12

CH₃_rock A A” 966 966 968 971 2 5

CH3 rock A A” 940 940 939 939 -1 -1

C-C str A A’ 932 932 992 980 60 48

C-C str A A’ 847 847 853 859 6 12

C-Cl str A A’ 687 563 690 580 3 17

O=C-Cl wag A A” 642 642 590 601 -52 -41

O=C-Cl def A A’ 437 437 459 545 22 108

O=C-Cl rock A A’ 416 416 414 420 -2 -4

C-C-C def A A’ 320 337 321 320 1 -17

C-C-C wag A A’ 310b ₃₁₀b ₂₉₈ ₂₃₆ _-12 _-74

C-C-C twist A A” 224 224 236 262 12 38

CH₃ torsion A A’ 228b ₂₂₈b ₂₃₆ ₂₂₅ ₈ _-3

CH₃ torsion A A” 222b ₂₂₂b ₂₀₇ ₂₀₉ _-15 _-13

torsion(as) A A” 110b ₁₁₀b ₅₆ ₅₆ _-54 _-54

rms deviation 29 37

a)Taken from reference 41 b).

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Table S2. Vibrational frequencies (in cm

-1

) of 2,2-dimethylpropionyl fluoride, chloride,

and bromide in the far-IR region (30 - 400 cm

-1

)

(CH

₃

)

₃

CCOF

(CH

₃

)

₃

CCOCl

(CH

₃

)

₃

CCOBr

assignment symm. IR(gas)a _{MM3 MM3-IR}a _IR(gas)b _{MM3 MM3-IR}b _{Ab initio}c _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.

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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).