ab initio and dft calculations for the vibrational frequencies and barrier to planarity of...

Ab Initio and DFT Calculations for the Vibrational Frequencies and Barrier to Planarity of Cyclopentene

and its Deuterated Isotopomers

Abdulaziz Al-Saadi and Jaan LaaneDepartment of ChemistryTexas A&M UniversityCollege Station, Texas

2

Cyclopentene-d0 , -d1 , -d4 , and -d8

• We had previously determined the IR and Raman spectra, calculated the 1D and 2D PES, and ran a MM investigation of the four molecules.

• Cyclopentene exists in the puckered form with a puckering angle of 26º based on spectroscopic determination.

DD

D

D

DD

D

D

d0 d8

D DD

D

D

d1 d4

Planar

Puckered

C2v Cs

Cs C1

Symmetry Species 11A1 + 6A2 + 9B1 + 7B2 20A’ + 13A”

φ = 26o

C2

z

x

(1) Villarreal, J. R.; Laane, J.; Bush, S. F.; Harris, W. C., Spectrochem. Acta, 1979, 35A, 331.(2) Laane, J., Lord, R. C., J. Chem. Phys., 1967, 47, 4941.(3) Rosas, R. L. , Cooper, C., and Laane, J., J. Chem. Phys., 1990, 94,1830.

1-3

3

Cyclopentene-d0 , -d1 , -d4 , and -d8

In this work we:• Optimized the structure cyclopentene-d0 in the planar and puckered

conformations using the MP2 and DFT theories with the 6-311++G** and cc-pVTZ basis sets.

• Predicted the zero-point energy, puckering barrier and puckering angle of cyclopentene-d0 .

• Calculated the vibrational frequencies of the two structures for cyclopentene-d0, -d1, -d4, and -d8 molecules from density functional theory and then compared the assignments with the experimental ones.

• Made several vibrational reassignments for the d0, d1, d4 and d8 isotopomers.

• Obtained the liquid IR and Raman spectra for cyclopentene-d0 to help confirm our reassignments.

4

Calculated Structure of Cyclopentene-d0

H

H

HH

HH

H

H

H

H

HH

HH

H

H

1.550 1.540 (1.544)

1.503 1.506 (1.519)

1.3381.335

1.087 1.0901.088

1.090

1.094

1.091

1.0811.081 (1.341)

104.0o 102.4o

111.6o

(111.2o)112.6o

105.1o106.9o

124.8o124.5o

(121.8o)

110.8o 113.8o

107.9o

107.0o (104.8o)

106.5o107.5o

(101.8o)

Experimental values of GEDare shown in red 1

(1) Davis, M. I.; Mueche, T. W.; J. Phys. Chem., 1970, 74, 1104.

C2v Cs

5

Experimental and Calculated Puckering Barrier and Puckering Angle

Expt.

Calculated

MP2/DZ 1 MP2/6-311++G**

MP2/cc-pVTZ

DFT-B3LYP/ 6-311++G**

DFT-B3LYP/cc-pVTZ

τ 2.3 3.0 3.1 2.3 2.1

φ 28.8 GED 2 23.4 27.1 26.1 20.0 19.3

22.2 MW 3

26 Far-IR 4

Puckering Barrier (cm-1) 233 4 177.1 297.97 246.68 59.78 41.68

Hτ

φ

(1) Allen, W. D.; Csaszar, A. G.; Horner, D. A., J. Am. Chem. Soc., 1992, 114, 6834.(2) Davis, M. I.; Mueche, T. W.; J. Phys. Chem., 1970, 74, 1104.(3) Rathjens, G. W., J. Chem. Phys., 1962, 36, 2401.(4) Laane, J., Lord, R. C., J. Chem. Phys., 1967, 47, 4941.

6

Calculated Ring-Puckering & Ring-Twisting Frequencies in Cyclopentene-d0 , -d1 , -d4 , and -d8

Expt.

puck 1 twist 2

Calculated (Scaled)

B3LYP/6-311++G** B3LYP/cc-pVTZ

IR IR Ram puck twist puck twist

d0 127 390 135 385 130 387

d1 126 369 369 137 370 129 372

d4 120 337 338 128 337 120 338

d8 108 317 109 318 103 320

+ _

_ +

+

_ _

+ +

Ring Twisting (17)Ring Puckering (33)

(1) Laane, J., Lord, R. C., J. Chem. Phys., 1967, 47, 4941.(2) Villarreal, J. R.; Laane, J.; Bush, S. F.; Harris, W. C., Spectrochem. Acta, 1979, 35A, 331.

7

Assignments

Observed * Calculated (Scaled) at DFT-B3LYP

Vapor IR 1

Vapor Raman 1

Liquid IR 2

Cs C2v

6-311++G** cc-pVTZ 6-311++G** cc-pVTZ

A1 1 CH sym. str. 3078 s 3070 (140) 3057 (23,187) 3068 (23,186) 3064 (23,187) 3066 (24,187)

2 β-CH2 sym. str. 2903 s 2900 (7) 2897 m 2935 (55,183) 2937 (56,173) 2939 (46,168) 2942 (44,154)

3 α-CH2 sym. str. (i.p.) 2860 s 2857 (153) 2848 vs 2879 (31,240) 2881 (31,218) 2913 (1,282) 2896 (2,267)

4 C=C str. 1623 m 1617 (91) 1610 m 1640 (3,250) 1649 (2,143) 1650 (4,206) 1657 (3,125)

5 β-CH2 def. 1471 vw 1473 (16) 1479 (3,43) 1481 (2,57) 1485 (4,41) 1486 (3,56)

6 α-CH2 def. (i.p.) 1445 m 1448 (23) 1463 m 1454 (2,136) 1459 (1,143) 1459 (0,129) 1459 (0,138)

7 α-CH2 wag (i.p.) 1290 m 1302 (10) 1295 m 1300 (1,21) 1303 (1,21) 1303 (1,18) 1306 (1,19)

8 CH in-plane bend (i.p.) 1101 w 1109 (66) 1108 vw 1107 (0,136) 1111 (0,129) 1108 (0,118) 1112 (0,119)

9 Ring str. 962 w 962 (55) 963 m 954 (1,57) 955 (1,50) 957 (1,35) 958 (1,31)

10 Ring breathing 900 m 896 (100) 903 s 885 (1,100) 885 (0,100) 875 (0,100) 875 (0,100)

11 Ring def. 608 w 600 (1) 603 m 604 (14,7) 608 (12,7) 689 (0,5) 691 (0,11)

A2 12 α-CH2 antisym. str. (o.p.) 2938 (54) 2924 (37,121) 2924 (37,120) 2913 (0,188) 2913 (0,184)

13 α-CH2 twist (o.p.) 1209 (2) 1279 w 1282 (2,7) 1287 (2,7) 1249 (0,23) 1253 (0,25)

14 β-CH2 twist 1134 (1) 1131 (2,0) 1132 (1,0) 1139 (0,2) 1140 (0,3)

15 CH out-of-plane bend (o.p.) 1047 (1) 955 (0,7) 961 (0,7) 958 (0,10) 965 (0,5)

16 α-CH2 rock (o.p.) 879 (1) 872 (4,7) 875 (4,7) 889 (0,4) 893 (0,3)

17 Ring twist 390 (2) 385 (0,14) 387 (0,21) 370 (0,8) 374 (0,11)

B1 18 CH antisym. str. 3068 s 3062 (18) 3055 s 3043 (8,87) 3044 (8,87) 3040 (8,88) 3043 (8,87)19 α-CH2 sym. str. (o.p.) 2873 s 2882 (57) 2866 s 2880 (55,82) 2883 (54,75) 2895 (97,40) 2896 (95,33)

20 α-CH2 def. (o.p.) 1438 vw 1444 m 1460 (3,71) 1463 (2,71) 1464 (3,53) 1466 (2,56)

21 CH in-plane bend (o.p.) 1353 m 1354 (2) 1350 vw 1351 (2,0) 1358 (2,0) 1352 (2,1) 1360 (1,3)

22 α-CH2 wag (o.p.) 1268 m 1297 (5) 1291 (0,7) 1296 (0,7) 1287 (2,0) 1295 (1,0)

23 β-CH2 wag 1128 w 1167 vw 1201 (0,36) 1205 (0,29) 1246 (0,25) 1247 (1,19)

24 Ring str. 1037 w 1030 (1) 1025 w 1014 (2,36) 1015 (2,29) 1018 (2,24) 1071 (2,18)

25 Ring str. 933 w 933 (2) 899 (8,0) 900 (7,0) 891 (12,7) 891 (11,5)

26 Ring def. 695 s 690 (1) 770 vw 768 (0,7) 771 (0,7) 773 (1,6) 776 (1,4)

B2 27 α-CH2 antisym. str. (i.p.) 2963 s 2973 (39) 2949 s 2969 (44,87) 2970 (43,84) 2972 (43,74) 2973 (43,74)28 β-CH2 antisym. str. 2933 s 2929 (30) 2925 s 2916 (5,66) 2918 (4,61) 2910 (33,3) 2910 (35,2)

29 α-CH2 twist (i.p.) 1207 m 1205 m 1207 (2,50) 1209 (2,43) 1201 (2,40) 1204 (2,38)

30 α-CH2 rock (i.p.) 1047 s 1047 (1) 1043 s 1047 (8,7) 1052 (7,7) 1042 (9,2) 1048 (8,3)

31 CH out-of-plane bend (i.p.) 695 s 696 s 699 (39,14) 702 (31,21) 660 (46,8) 663 (37,16)

32 β-CH2 rock 593 m 803 vw 802 (1,7) 803 (1,7) 766 (8,9) 770 (7,11)

33 Ring puckering 127.1 135 (0,14) 130 (0,7)

Experimental and Calculated Frequencies for Cyclopentene

(1) Villarreal, J. R.; Laane, J.; Bush, S. F.; Harris, W. C., Spectrochem. Acta, 1979, 35A, 331.(2) This work.* Values shown in italic are from condensed-phase experiments.

8

Vibrational Reassignments for Cyclopentene

Assignments

Observed * Calculated (Scaled) at DFT-B3LYP

Vapor IR 1

Vapor Raman 1 Liquid IR 2

Cs C2v

6-311++G** cc-pVTZ 6-311++G** cc-pVTZ

A1 1 CH sym. str. 3078 s 3070 (140) 3057 (23,187) 3068 (23,186) 3064 (23,187) 3066 (24,187)

2 β-CH2 sym. str. 2903 s 2900 (7) 2897 m 2935 (55,183) 2937 (56,173) 2939 (46,168) 2942 (44,154)

3 α-CH2 sym. str. (i.p.) 2860 s 2857 (153) 2848 vs 2879 (31,240) 2881 (31,218) 2913 (1,282) 2896 (2,267)

4 C=C str. 1623 m 1617 (91) 1610 m 1640 (3,250) 1649 (2,143) 1650 (4,206) 1657 (3,125)

5 β-CH2 def. 1471 vw 1473 (16) 1479 (3,43) 1481 (2,57) 1485 (4,41) 1486 (3,56)

6 α-CH2 def. (i.p.) 1445 m 1448 (23) 1463 m 1454 (2,136) 1459 (1,143) 1459 (0,129) 1459 (0,138)

7 α-CH2 wag (i.p.) 1290 m 1302 (10) 1295 m 1300 (1,21) 1303 (1,21) 1303 (1,18) 1306 (1,19)

8 CH in-plane bend (i.p.) 1101 w 1109 (66) 1108 vw 1107 (0,136) 1111 (0,129) 1108 (0,118) 1112 (0,119)

9 Ring str. 962 w 962 (55) 963 m 954 (1,57) 955 (1,50) 957 (1,35) 958 (1,31)

10 Ring breathing 900 m 896 (100) 903 s 885 (1,100) 885 (0,100) 875 (0,100) 875 (0,100)

11 Ring def. 593 m 600 (1) 603 m 604 (14,7) 608 (12,7) 689 (0,5) 691 (0,11)

A2 12 α-CH2 antisym. str. (o.p.) 2938 (54) 2924 (37,121) 2924 (37,120) 2913 (0,188) 2913 (0,184)

13 α-CH2 twist (o.p.) 1268 m 1279 w 1282 (2,7) 1287 (2,7) 1249 (0,23) 1253 (0,25)

14 β-CH2 twist 1128 w 1134 (1) 1131 (2,0) 1132 (1,0) 1139 (0,2) 1140 (0,3)

15 CH out-of-plane bend (o.p.) 955 (0,7) 961 (0,7) 958 (0,10) 965 (0,5)

16 α-CH2 rock (o.p.) 879 (1) 872 (4,7) 875 (4,7) 889 (0,4) 893 (0,3)

17 Ring twist 390 (2) 385 (0,14) 387 (0,21) 370 (0,8) 374 (0,11)

B1 18 CH antisym. str. 3068 s 3062 (18) 3055 s 3043 (8,87) 3044 (8,87) 3040 (8,88) 3043 (8,87)19 α-CH2 sym. str. (o.p.) 2873 s 2882 (57) 2866 s 2880 (55,82) 2883 (54,75) 2895 (97,40) 2896 (95,33)

20 α-CH2 def. (o.p.) 1438 vw 1444 m 1460 (3,71) 1463 (2,71) 1464 (3,53) 1466 (2,56)

21 CH in-plane bend (o.p.) 1353 m 1354 (2) 1350 vw 1351 (2,0) 1358 (2,0) 1352 (2,1) 1360 (1,3)

22 α-CH2 wag (o.p.) 1297 (5) 1291 (0,7) 1296 (0,7) 1287 (2,0) 1295 (1,0)

23 β-CH2 wag 1167 vw 1201 (0,36) 1205 (0,29) 1246 (0,25) 1247 (1,19)

24 Ring str. 1037 w 1030 (1) 1025 w 1014 (2,36) 1015 (2,29) 1018 (2,24) 1071 (2,18)

25 Ring str. 933 w 933 (2) 899 (8,0) 900 (7,0) 891 (12,7) 891 (11,5)

26 Ring def. 770 vw 768 (0,7) 771 (0,7) 773 (1,6) 776 (1,4)

B2 27 α-CH2 antisym. str. (i.p.) 2933 s 2929 (30) 2925 s 2916 (5,66) 2918 (4,61) 2910 (33,3) 2910 (35,2)28 β-CH2 antisym. str. 2963 s 2973 (39) 2949 s 2969 (44,87) 2970 (43,84) 2972 (43,74) 2973 (43,74)

29 α-CH2 twist (i.p.) 1207 m 1209 (2) 1205 m 1207 (2,50) 1209 (2,43) 1201 (2,40) 1204 (2,38)

30 α-CH2 rock (i.p.) 1047 s 1047 (1) 1043 s 1047 (8,7) 1052 (7,7) 1042 (9,2) 1048 (8,3)

31 CH out-of-plane bend (i.p.) 695 s 690 (1) 696 s 699 (39,14) 702 (31,21) 660 (46,8) 663 (37,16)

32 β-CH2 rock 803 vw 802 (1,7) 803 (1,7) 766 (8,9) 770 (7,11)

33 Ring puckering 127.1 135 (0,14) 130 (0,7)

(1) Villarreal, J. R.; Laane, J.; Bush, S. F.; Harris, W. C., Spectrochem. Acta, 1979, 35A, 331.(2) This work.* Values shown in italic are from condensed-phase experiments.

9

Vibrational Reassignments for Cyclopentene-d8

AssignmentsObserved * Calculated (Scaled) at DFT-B3LYP

Vapor IR 1

Vapor Raman 1

Cs C2v

6-311++G** cc-pVTZ 6-311++G** cc-pVTZA1 1 CD sym. str. 2310 s 2305 (68) 2314 (9,74) 2315 (9,78) 2313 (9,74) 2314 (10,78)

2 β-CD2 sym. str. 2153 w 2145 (100) 2157 (18,75) 2160 (18,67) 2166 (23,84) 2168 (22,77)3 α-CD2 sym. str. (i.p.) 2100 (136) 2126 (11,141) 2128 (10,132) 2132 (0,143) 2135 (1,134)4 C=C str. 1580 m 1577 (50) 1591 (6,205) 1600 (4,143) 1602 (6,76) 1609 (5,123)5 β-CD2 def. 1110 w 1113 (7) 1109 (1,14) 1110 (1,14) 1110 (2,13) 1110 (1,11)6 α-CD2 def. (i.p.) 1070 m 1072 (2) 1068 (1,18) 1071 (1,19) 1069 (0,16) 1072 (0,18)7 α-CD2 wag (i.p.) 750 w 750 (7) 743 (1,14) 744 (1,13) 749 (1,16) 750 (0,14)8 CD in-plane bend (i.p.) 853 w 850 (7) 783 (0,32) 785 (0,38) 779 (0,33) 781 (0,33)9 Ring str. 1150 vw 1158 (2) 1148 (0,6) 1149 (1,4) 1149 (0,4) 1148 (0,6)10 Ring breathing 878 m 878 (100) 869 (3,100) 871 (2,100) 863 (1,100) 865 (0,100)11 Ring def. 682 (0,4) 681 (0,3) 643 (0,5) 645 (0,6)

A2 12 α-CD2 antisym. str. (o.p.) 2202 (15) 2191 (7,79) 2190 (7,79) 2185 (0,98) 2186 (0.96)13 α-CD2 twist (o.p.) 868 w 860 (5) 887 (2,18) 890 (1,19) 888 (0,16) 891 (0,16)14 β-CD2 twist 921 w 930 (1) 926 (0,5) 929 (0,4) 926 (0,4) 930 (0,2)15 CD out-of-plane bend (o.p.) 724 m 720 (6) 725 (2,5) 728 (1,3) 730 (0,4) 733 (0,4)16 α-CD2 rock (o.p.) 667 658 (0,0) 661 (0,0) 670 (0,0) 673 (0,0)17 Ring twist 317 (2) 318 (0,6) 320 (2,9) 305 (0,4) 308 (0,7)

B1 18 CD antisym. str. 2276 m 2268 (15) 2268 (3,44) 2270 (3,44) 2267 (3,44) 2268 (3,44)19 α-CD2 sym. str. (o.p.) 2138 m 2132 (20) 2126 (37,29) 2128 (38,24) 2131 (47,24) 2133 (46,19)20 α-CD2 def. (o.p.) 1062 m 1060 (2,14) 1062 (2,14) 1058 (2,11) 1059 (1,9)21 CD in-plane bend (o.p.) 709 w 715 705 (7,5) 707 (6,2) 705 (9,2) 706 (8,2)22 α-CD2 wag (o.p.) 1024 vw 1020 (1,0) 1027 (1,0) 1023 (1,0) 1029 (1,0)23 β-CD2 wag 790 (7) 786 (0,23) 788 (0,20) 804 (0,19) 804 (0,14)24 Ring str. 1124 (1,4) 1122 (1,3) 1114 (1,5) 1113 (1,6)25 Ring str. 1191 (0,9) 1195 (0,10) 1195 (1,9) 1198 (1,9)26 Ring def. 754 (1,1) 757 (1,0) 758 (1,1) 760 (1,3)

B2 27 α-CD2 antisym. str. (i.p.) 2200 s 2202 (15) 2193 (22,34) 2192 (23,31) 2185 (24,3) 2186 (24,2)28 β-CD2 antisym. str. 2230 s 2235 (30) 2229 (22,41) 2230 (22,40) 2232 (20,36) 2233 (20,37)29 α-CD2 twist (i.p.) 849 s 848 (6,27) 852 (5,29) 854 (9,9) 857 (8,9)30 α-CD2 rock (i.p.) 954 w 950 (1) 951 (0,10) 954 (0,8) 939 (0,7) 943 (0,5)31 CD out-of-plane bend (i.p.) 465 s 460 (1) 460 (16,5) 464 (13,3) 481 (24,3) 483 (19,6)32 β-CD2 rock 543 s 550 (1) 546 (13,4) 549 (10,8) 571 (5,3) 574 (4,4)33 Ring puckering 108.2 109 (0,3) 103 (0,1)

(1) Villarreal, J. R.; Laane, J.; Bush, S. F.; Harris, W. C., Spectrochem. Acta, 1979, 35A, 331.* Values shown in italic are from condensed-phase experiments.

10

Vibrational Reassignments for 1-Cyclopentene-d1

Assignments

Observed (*) Calculated (Scaled) at DFT-B3LYP

Vapor IR 1

Vapor Raman 1

C1 Cs

6-311++G** cc-pVTZ 6-311++G** cc-pVTZ

A’ 1 CH str. 3065 m 3066 (188) 3054 (15,138) 3056 (16,138) 3051 (15,139) 3054 (16,139)2 β-CH2 sym. str. 2903 s 2904 (122) 2935 (53,188) 2937 (54,178) 2939 (45,172) 2943 (43,157)3 α-CH2 sym. str. 2865 s 2879 (105) 2880 (54,80) 2882 (53,74) 2895 (25,225) 2897 (12,246)4 α-CH2 sym. str 2859 s 2859 (224) 2879 (32,242) 2881 (31,220) 2895 (73,99) 2896 (85,57)5 =C-D str. 2294 m 2290 (37) 2291 (6,54) 2293 (7,55) 2288 (6,54) 2291 (7,56)6 C=C str. 1600 m 1597 (79) 1619 (4,270) 1628 (3,177) 1628 (5,229) 1637 (4,153)7 β-CH2 def. 1470 m 1472 (22) 1479 (3,42) 1481 (2,62) 1484 (4,41) 1486 (3,66)8 α-CH2 def. 1446 m 1448 (32) 1461 (3,76) 1464 (2,77) 1463 (3,53) 1466 (2,60)9 α-CH2 def. 1435 w 1455 (2,136) 1458 (1,154) 1455 (0,124) 1459 (0,153)10 CH in-plane bend 1261 m 1257 (3) 1254 (1,21) 1263 (1,15) 1260 (1,16) 1266 (1,14)11 α-CH2 wag 1300 w 1298 (10) 1299 (1,13) 1303 (1,17) 1302 (1,12) 1305 (1,13)12 α-CH2 wag 1322 s 1327 (5) 1324 (2,4) 1329 (2,6) 1325 (2,4) 1330 (2,9)13 β-CH2 wag 1116 w 1121 (1) 1286 (2,11) 1288 (2,14) 1240 (0,31) 1242 (0,21)14 Ring str. 1033 m 1029 (8) 1019 (3,39) 1020 (3,38) 1023 (3,29) 1023 (3,31)15 CD in-plane bend 988 w 978 (65) 969 (1,86) 971 (2,85) 965 (2,76) 967 (2,64)16 Ring str. 966 w 952 (33) 945 (2,49) 946 (2,38) 950 (2,35) 950 (1,33)17 Ring breathing 893 w 899 (100) 886 (2,100) 886 (2,100) 876 (1,100) 877 (1,100)18 Ring str. 750 w 750 (1) 745 (3,6) 747 (3,15) 748 (3,12) 751 (3,13)19 Ring def. 698 w 708 (8) 772 (1,7) 774 (1,8) 797 (3,11) 800 (3,10)20 Ring def. 634 s 630 (1) 638 (6,5) 642 (4,6) 680 (0,5) 683 (0,6)

A” 21 α-CH2 antisym. str. 2939 s 2939 (126) 2925 (38,118) 2925 (38,117) 2913 (0,188) 2913 (0,184)22 α-CH2 antisym. str. 2939 s 2924 (126) 2917 (6,66) 2918 (4,61) 2911 (3,33) 2910 (35,2)23 β-CH2 antisym. str. 2962 s 2969 (60) 2969 (44,87) 2969 (43,84) 2972 (43,74) 2973 (43,74)24 α-CH2 twist 1211 s 1202 (2) 1206 (2,46) 1208 (2,43) 1200 (1,40) 1203 (1,41)25 α-CH2 twist 1137 w 1138 1131 (2,1) 1133 (1,2) 1139 (0,2) 1140 (0,3)26 β-CH2 twist 1207 w 1196 (0,45) 1199 (0,38) 1249 (0,22) 1253 (0,27)27 α-CH2 rock 1044 s 1045 1043 (6,5) 1048 (6,5) 1038 (7,2) 1044 (6,5)28 CH out-of-plane bend 897 (2,15) 902 (2,17) 910 (1,18) 915 (1,13)29 α-CH2 rock 855 s 855 (1) 860 (4,3) 864 (3,18) 861 (5,4) 866 (4,10)30 β-CH2 rock 812 (3,4) 813 (3,6) 744 (0,1) 747 (0,4)31 CD out-of-plane bend 565 s 565 (1) 563 (30,7) 567 (25,15) 578 (37,7) 579 (30,12)32 Ring twist 369 w 369 (3) 370 (0,5) 372 (0,10) 355 (0,5) 359 (0,12)33 Ring puckering 126 137 (0,3) 129 (0,4)


11

AssignmentsObserved * Calculated (Scaled) at DFT-B3LYP

Vapor IR 1

Vapor Raman 1

C1 Cs

6-311++G** cc-pVTZ 6-311++G** cc-pVTZA’ 1 CD str. 2310 m 2313 (13) 2314 (10,67) 2315 (11,71) 2312 (10,68) 2314 (11,72)

2 β-CH2 sym. str. 2941 s 2941 (20) 2933 (52,165) 2934 (52,156) 2938 (43,146) 2941 (41,134)3 α-CD2 sym. str. 2110 s 2100 (51) 2127 (24,95) 2128 (24,87) 2134 (25,97) 2135 (24,89)4 α-CH2 sym. str 2854 s 2861 (46) 2879 (41,167) 2882 (41,152) 2895 (49,167) 2897 (48,156)5 =C-D str. 2277 m 2265 (5) 2268 (3,45) 2270 (3,44) 2266 (3,45) 2268 (3,44)6 C=C str. 1560 m 1580 (51) 1595 (4,195) 1604 (4,141) 1605 (6,191) 1613 (5,132)7 β-CH2 def. 1460 m 1467 (4) 1474 (3,23) 1477 (1,27) 1480 (3,22) 1483 (2,30)8 α-CH2 def. 1449 m 1452 (7) 1457 (2,72) 1459 (1,82) 1458 (1,74) 1461 (1,77)9 α-CD2 def. 1081 vw 1085 (4) 1081 (0,18) 1084 (0,20) 1082 (0,17) 1085 (0,22)10 CD in-plane bend 800 w 802 (3) 796 (0,27) 798 (0,28) 792 (0,28) 793 (0,32)11 α-CH2 wag 1286 w 1290 (1) 1284 (1,9) 1286 (1,10) 1270 (1,13) 1272 (1,18)12 α-CD2 wag 821 m 825 (7) 813 (1,18) 815 (1,22) 822 (1,30) 823 (1,27)13 β-CH2 wag 1027 w 1309 (2,4) 1314 (1,8) 1310 (2,2) 1315 (1,2)14 Ring str. 1107 m 1100 (1) 1101 (3,8) 1104 (2,6) 1099 (3,8) 1102 (2,8)15 CD in-plane bend 715 vw 719 714 (2,3) 715 (2,4) 716 (7,4) 719 (7,4)16 Ring str. 1143 w 1151 (0,10) 1153 (0,7) 1164 (1,9) 1167 (1,9)17 Ring breathing 910 m 910 (100) 901 (1,100) 903 (1,100) 894 (1,100) 897 (1,100)18 Ring str. 985 vw 985 (2) 973 (0,23) 974 (0,20) 979 (0,17) 978 (0,14)19 Ring def. 725 w 726 (1) 767 (1,6) 769 (1,9) 769 (2,4) 771 (2,3)20 Ring def. 604 m 604 (1) 603 (4,3) 607 (4,5) 661 (0,5) 664 (0,4)

599 s

A” 21 α-CH2 antisym. str. 2904 s 2905 (20) 2919 (18,78) 2920 (17,74) 2912 (17,92) 2913 (18,90)22 α-CD2 antisym. str. 2200 s 2194 (10) 2192 (16,55) 2191 (16,53) 2187 (15,53) 2187 (15,51)23 β-CH2 antisym. str. 2964 s 2969 (30) 2967 (37,87) 2969 (36,84) 2970 (33,71) 2971 (33,72)24 α-CH2 twist 1163 vw 1160 (1) 1163 (2,16) 1166 (1,15) 1160 (0,11) 1162 (0,14)25 α-CD2 twist 872 s 875 (4) 872 (4,20) 875 (3,24) 874 (4,13) 878 (3,11)26 β-CH2 twist 1226 1211 (1) 1226 (0,13) 1229 (0,15) 1236 (0,22) 1240 (0,19)27 α-CH2 rock 1041 s 1045 (1) 1038 (2,8) 1042 (2,4) 1031 (1,4) 1037 (1,3)28 CD out-of-plane bend 735 w 733 (1) 733 (3,8) 736 (3,4) 723 (1,4) 729 (1,3)29 α-CD2 rock 703 (2,1) 706 (2,2) 666 (1,5) 669 (0,1)30 β-CH2 rock 858 m 860 (3) 848 (1,4) 849 (1,8) 841 (0,3) 844 (0,2)31 CD out-of-plane bend 502 s 500 (1) 502 (28,2) 506 (23,8) 511 (31,4) 514 (26,12)32 Ring twist 337 w 338 (2) 337 (0,4) 338 (0,6) 323 (0,3) 327 (0,7)33 Ring puckering 120.0 128 (0,3) 120 (0,2)

Vibrational Reassignments for 1,2,3,3-Cyclopentene-d4


12

Numbers of Revised Assignments in Cyclopentene-d0 , -d1 , -d4 , and -d8

# of Vibrations Reassigned

Cyclopentene-d0 5

Cyclopentene-d1 7

Cyclopentene-d4 16

Cyclopentene-d8 14

13

Experimental (Liquid-phase) and Calculated Infrared Spectra of Cyclopentene

5x

4x

14

Experimental (Liquid-phase) and Calculated Raman Spectra of Cyclopentene

10x5x

15

Conclusions

• Conformational structures and vibrational frequencies of cyclopentene and its deuterated isotopomers were studied with ab initio calculations, and the results were compared with previously reported experimental results.

• The barrier to planarity predicted by the MP2 theory (247 cm-1) agrees very well with our previously far-IR data (233 cm-1). The DFT barrier (42 cm-1), however, was predicted to be considerably low.

• DFT calculated frequencies using the 6-311++G** and cc-pVTZ basis sets agree very well with experimental frequencies (even though the calculated band intensities are not as good) and help in reassigning some vibrational modes in the four molecules.

• The MP2 method gives a more reliable prediction of the calculated energies and structures while the DFT method predicts the frequencies very well.

16

Acknowledgments

• The National Science Foundation.• The Robert A. Welch Foundation.• The Texas Advance Research Program.

17

Calculated Structure of Cyclopentene-d0

H

H

HH

HH

H

H

H

H

HH

HH

H

H

1.550 1.540 (1.544)

1.503 1.506 (1.519)

1.3381.335

1.087 1.0901.088

1.090

1.094

1.091

1.0811.081

H

H

HH

HH

H

H

H

H

HH

HH

H

H

1.555 1.544

1.509 1.512

1.3451.343

1.093 1.0951.093

1.095

1.099

1.096

1.0811.081

MP2/cc-pVTZ

MP2/6-311++G**

(1.341)

104.1o 102.4o

104.0o 102.4o

111.6o

(111.2o)112.6o

112.5o 111.4o

105.1o106.9o

106.8o 105.0o

124.6o 124.9o

124.8o124.5o

(121.8o)

110.8o 113.8o

113.0o110.7o

107.9o

107.0o

108.2o107.2o

(104.8o)

106.5o107.5o

106.8o 107.3o

(101.8o)

Experimental values of GEDare shown in red 1

(1) Davis, M. I.; Mueche, T. W.; J. Phys. Chem., 1970, 74, 1104.

C2v Cs

18

Assignments

Observed 1 Calculated (Scaled) at DFT-B3LYP

Comments from

CalculationVapor

IR *

Vapor Raman *

Cs C2v

6-311++G** cc-pVTZ 6-311++G** cc-pVTZ

A1 1 CD sym. str. 2310 s 2305 (68) 2314 (9,74) 2315 (9,78) 2313 (9,74) 2314 (10,78)

2 β-CD2 sym. str. 2153 w 2145 (100) 2157 (18,75) 2160 (18,67) 2166 (23,84) 2168 (22,77)

3 α-CD2 sym. str. (i.p.) 2100 (136) 2126 (11,141) 2128 (10,132) 2132 (0,143) 2135 (1,134)

4 C=C str. 1580 m 1577 (50) 1591 (6,205) 1600 (4,143) 1602 (6,76) 1609 (5,123)

5 β-CD2 def. 1110 w 1113 (7) 1109 (1,14) 1110 (1,14) 1110 (2,13) 1110 (1,11)

6 α-CD2 def. (i.p.) 1070 m 1072 (2) 1068 (1,18) 1071 (1,19) 1069 (0,16) 1072 (0,18)

7 α-CD2 wag (i.p.) 921 w 930 (1) 926 (0,5) 929 (0,4) 926 (0,4) 930 (0,2) 14

8 CD in-plane bend (i.p.) 853 w 850 (7) 783 (0,32) 785 (0,38) 779 (0,33) 781 (0,33)

9 Ring str. 750 w 750 (7) 743 (1,14) 744 (1,13) 749 (1,16) 750 (0,14) 7

10 Ring breathing 878 m 878 (100) 869 (3,100) 871 (2,100) 863 (1,100) 865 (0,100)

11 Ring def. 574 w ? 682 (0,4) 681 (0,3) 643 (0,5) 645 (0,6)

A2 12 α-CD2 antisym. str. (o.p.) 2202 (15) 2191 (7,79) 2190 (7,79) 2185 (0,98) 2186 (0.96)

13 α-CD2 twist (o.p.) 790 (7) 786 (0,23) 788 (0,20) 804 (0,19) 804 (0,14) 23

14 β-CD2 twist 1124 (1,4) 1122 (1,3) 1114 (1,5) 1113 (1,6) 24

15 CD out-of-plane bend (o.p.) 754 (1,1) 757 (1,0) 758 (1,1) 760 (1,3) 26

16 α-CD2 rock (o.p.) 667 658 (0,0) 661 (0,0) 670 (0,0) 673 (0,0)

17 Ring twist 317 (2) 318 (0,6) 320 (2,9) 305 (0,4) 308 (0,7)

B1 18 CD antisym. str. 2276 m 2268 (15) 2268 (3,44) 2270 (3,44) 2267 (3,44) 2268 (3,44)

19 α-CD2 sym. str. (o.p.) 2138 m 2132 (20) 2126 (37,29) 2128 (38,24) 2131 (47,24) 2133 (46,19)

20 α-CD2 def. (o.p.) 1062 m 1060 (2,14) 1062 (2,14) 1058 (2,11) 1059 (1,9)

21 CD in-plane bend (o.p.) 1150 vw 1158 (2) 1148 (0,6) 1149 (1,4) 1149 (0,4) 1148 (0,6) 9

22 α-CD2 wag (o.p.) 954 w 950 (1) 951 (0,10) 954 (0,8) 939 (0,7) 943 (0,5) 30

23 β-CD2 wag 868 w 860 (5) 887 (2,18) 890 (1,19) 888 (0,16) 891 (0,16) 13

24 Ring str. 1024 vw 1020 (1,0) 1027 (1,0) 1023 (1,0) 1029 (1,0)

25 Ring str. 724 m 720 (6) 725 (2,5) 728 (1,3) 730 (0,4) 733 (0,4) 15

26 Ring def. 709 w 715 705 (7,5) 707 (6,2) 705 (9,2) 706 (8,2) 21

B2 27 α-CD2 antisym. str. (i.p.) 2230 s 2235 (30) 2229 (22,41) 2230 (22,40) 2232 (20,36) 2233 (20,37) 28 28 β-CD2 antisym. str. 2200 s 2202 (15) 2193 (22,34) 2192 (23,31) 2185 (24,3) 2186 (24,2) 27

29 α-CD2 twist (i.p.) 878 m 878 1191 (0,9) 1195 (0,10) 1195 (1,9) 1198 (1,9) 25

30 α-CD2 rock (i.p.) 849 s 848 (6,27) 852 (5,29) 854 (9,9) 857 (8,9) 29

31 CD out-of-plane bend (i.p.) 543 s 550 (1) 546 (13,4) 549 (10,8) 571 (5,3) 574 (4,4) 32

32 β-CD2 rock 465 s 460 (1) 460 (16,5) 464 (13,3) 481 (24,3) 483 (19,6) 31

33 Ring puckering 108.2 109 (0,3) 103 (0,1) ---- ----


Experimental and Calculated Frequencies for Cyclopentene-d8

ab initio and dft calculations for the vibrational frequencies and barrier to planarity of...

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