Ab Initio and DFT Calculations
for the Vibrational Frequencies and
Barrier to Planarity of Cyclopentene
and its Deuterated Isotopomers
Abdulaziz Al-Saadi and Jaan Laane
Department of Chemistry
Texas A&M University
College Station, Texas
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.1-3
Cyclopentene exists in
the puckered form with
a puckering angle of
26º based on
spectroscopic
determination.
z
D
D
D
D
x
D
D
d0
Planar
Puckered
Symmetry Species
D
D
D
C2
D
d8
D
D
d1
D
d4
C2v
Cs
Cs
C1
11A1 + 6A2 + 9B1 + 7B2
20A’ + 13A”
φ = 26o
(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.
2
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.
3
Calculated Structure of Cyclopentene-d0
H
H 107.9o
H
107.0o
1.088
1.087
110.8o
H
106.9o
1.091
106.5o
H
H
111.6o
(111.2o)
1.081
H
H
H
C2v
1.094
H
1.503
1.335
Experimental values of GED
are shown in red 1
(1) Davis, M. I.; Mueche, T. W.; J. Phys. Chem., 1970, 74, 1104.
H
1.090
102.4o
112.6o
124.5o
1.540 (1.544)
105.1o
107.5o
(101.8o)
104.0o
H
1.090
113.8o
H
1.550
H
H
(104.8o)
124.8o
(121.8o)
1.338
(1.341)
1.506 (1.519)
1.081
H
Cs
4
Experimental and Calculated Puckering Barrier
and Puckering Angle
H
τ
φ
Calculated
Expt.
τ
φ
28.8 GED 2
22.2
MP2/DZ 1
MP2/
6-311++G**
MP2/
cc-pVTZ
DFT-B3LYP/
6-311++G**
DFT-B3LYP/
cc-pVTZ
2.3
3.0
3.1
2.3
2.1
23.4
27.1
26.1
20.0
19.3
297.97
246.68
59.78
41.68
MW 3
26 Far-IR 4
Puckering
Barrier (cm-1)
233 4
177.1
(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.
5
Calculated Ring-Puckering & Ring-Twisting
Frequencies in Cyclopentene-d0 , -d1 , -d4 , and -d8
+
_
_
+
_
+
Ring Puckering (33)
IR
Calculated (Scaled)
twist 2
IR
+
Ring Twisting (17)
Expt.
puck 1
_
+
B3LYP/6-311++G**
B3LYP/cc-pVTZ
Ram
puck
twist
puck
twist
390
135
385
130
387
d0
127
d1
126
369
369
137
370
129
372
d4
120
337
338
128
337
120
338
d8
108
317
109
318
103
320
(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.
6
Experimental and Calculated Frequencies for Cyclopentene
Observed *
Assignments
A1
A2
B1
B2
Vapor
IR 1
1
2
3
4
5
6
7
8
9
10
11
CH sym. str.
β-CH2 sym. str.
α-CH2 sym. str. (i.p.)
C=C str.
β-CH2 def.
α-CH2 def. (i.p.)
α-CH2 wag (i.p.)
CH in-plane bend (i.p.)
Ring str.
Ring breathing
Ring def.
12
13
14
15
16
17
α-CH2 antisym. str. (o.p.)
α-CH2 twist (o.p.)
β-CH2 twist
CH out-of-plane bend (o.p.)
α-CH2 rock (o.p.)
Ring twist
18
19
20
21
22
23
24
25
26
CH antisym. str.
α-CH2 sym. str. (o.p.)
α-CH2 def. (o.p.)
CH in-plane bend (o.p.)
α-CH2 wag (o.p.)
β-CH2 wag
Ring str.
Ring str.
Ring def.
3068
2873
1438
1353
1268
1128
1037
933
695
27
28
29
30
31
32
33
α-CH2 antisym. str. (i.p.)
β-CH2 antisym. str.
α-CH2 twist (i.p.)
α-CH2 rock (i.p.)
CH out-of-plane bend (i.p.)
β-CH2 rock
Ring puckering
2963 s
2933 s
1207 m
1047 s
695 s
593 m
127.1
3078
2903
2860
1623
1471
1445
1290
1101
962
900
608
s
s
s
m
vw
m
m
w
w
m
w
Vapor
Raman 1
3070 (140)
2900 (7)
2857 (153)
1617 (91)
1473 (16)
1448 (23)
1302 (10)
1109 (66)
962 (55)
896 (100)
600 (1)
2938 (54)
1209 (2)
1134 (1)
1047 (1)
879 (1)
390 (2)
s
s
vw
m
m
w
w
w
s
3062 (18)
2882 (57)
1354 (2)
1297 (5)
1030 (1)
933 (2)
690 (1)
2973 (39)
2929 (30)
1047 (1)
Calculated (Scaled) at DFT-B3LYP
Liquid
IR 2
2897 m
2848 vs
1610 m
1463 m
1295 m
1108 vw
963 m
903 s
603 m
1279 w
3055
2866
1444
1350
s
s
m
vw
1167 vw
1025 w
770 vw
2949
2925
1205
1043
696
803
s
s
m
s
s
vw
(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.
Cs
6-311++G**
C2v
cc-pVTZ
6-311++G**
cc-pVTZ
3057
2935
2879
1640
1479
1454
1300
1107
954
885
604
(23,187)
(55,183)
(31,240)
(3,250)
(3,43)
(2,136)
(1,21)
(0,136)
(1,57)
(1,100)
(14,7)
3068
2937
2881
1649
1481
1459
1303
1111
955
885
608
(23,186)
(56,173)
(31,218)
(2,143)
(2,57)
(1,143)
(1,21)
(0,129)
(1,50)
(0,100)
(12,7)
3064
2939
2913
1650
1485
1459
1303
1108
957
875
689
(23,187)
(46,168)
(1,282)
(4,206)
(4,41)
(0,129)
(1,18)
(0,118)
(1,35)
(0,100)
(0,5)
3066
2942
2896
1657
1486
1459
1306
1112
958
875
691
(24,187)
(44,154)
(2,267)
(3,125)
(3,56)
(0,138)
(1,19)
(0,119)
(1,31)
(0,100)
(0,11)
2924
1282
1131
955
872
385
(37,121)
(2,7)
(2,0)
(0,7)
(4,7)
(0,14)
2924
1287
1132
961
875
387
(37,120)
(2,7)
(1,0)
(0,7)
(4,7)
(0,21)
2913
1249
1139
958
889
370
(0,188)
(0,23)
(0,2)
(0,10)
(0,4)
(0,8)
2913
1253
1140
965
893
374
(0,184)
(0,25)
(0,3)
(0,5)
(0,3)
(0,11)
3043
2880
1460
1351
1291
1201
1014
899
768
(8,87)
(55,82)
(3,71)
(2,0)
(0,7)
(0,36)
(2,36)
(8,0)
(0,7)
3044
2883
1463
1358
1296
1205
1015
900
771
(8,87)
(54,75)
(2,71)
(2,0)
(0,7)
(0,29)
(2,29)
(7,0)
(0,7)
3040
2895
1464
1352
1287
1246
1018
891
773
(8,88)
(97,40)
(3,53)
(2,1)
(2,0)
(0,25)
(2,24)
(12,7)
(1,6)
3043
2896
1466
1360
1295
1247
1071
891
776
(8,87)
(95,33)
(2,56)
(1,3)
(1,0)
(1,19)
(2,18)
(11,5)
(1,4)
2969
2916
1207
1047
699
802
135
(44,87)
(5,66)
(2,50)
(8,7)
(39,14)
(1,7)
(0,14)
2970
2918
1209
1052
702
803
130
(43,84)
(4,61)
(2,43)
(7,7)
(31,21)
(1,7)
(0,7)
2972
2910
1201
1042
660
766
(43,74)
(33,3)
(2,40)
(9,2)
(46,8)
(8,9)
2973
2910
1204
1048
663
770
(43,74)
(35,2)
(2,38)
(8,3)
(37,16)
(7,11)
7
Vibrational Reassignments for Cyclopentene
Observed *
Assignments
A1
1
2
3
4
5
6
7
8
9
10
11
A2
B1
B2
CH sym. str.
β-CH2 sym. str.
α-CH2 sym. str. (i.p.)
C=C str.
β-CH2 def.
α-CH2 def. (i.p.)
α-CH2 wag (i.p.)
CH in-plane bend (i.p.)
Ring str.
Ring breathing
Ring def.
12 α-CH2 antisym. str. (o.p.)
13 α-CH2 twist (o.p.)
14 β-CH2 twist
15 CH out-of-plane bend (o.p.)
16 α-CH2 rock (o.p.)
17 Ring twist
18
19
20
21
22
23
24
25
26
CH antisym. str.
α-CH2 sym. str. (o.p.)
α-CH2 def. (o.p.)
CH in-plane bend (o.p.)
α-CH2 wag (o.p.)
β-CH2 wag
Ring str.
Ring str.
Ring def.
27 α-CH2 antisym. str. (i.p.)
28 β-CH2 antisym. str.
29
30
31
32
33
α-CH2 twist (i.p.)
α-CH2 rock (i.p.)
CH out-of-plane bend (i.p.)
β-CH2 rock
Ring puckering
Vapor
IR 1
3078
2903
2860
1623
1471
1445
1290
1101
962
900
593
s
s
s
m
vw
m
m
w
w
m
m
Vapor
Raman 1
3070 (140)
2900 (7)
2857 (153)
1617 (91)
1473 (16)
1448 (23)
1302 (10)
1109 (66)
962 (55)
896 (100)
600 (1)
Calculated (Scaled) at DFT-B3LYP
Liquid IR 2
2897 m
2848 vs
1610 m
1463 m
1295 m
1108 vw
963 m
903 s
603 m
2938 (54)
1268 m
1128 w
1279 w
1134 (1)
879 (1)
390 (2)
3068
2873
1438
1353
s
s
vw
m
1037 w
933 w
3062 (18)
2882 (57)
1354 (2)
1297 (5)
1030 (1)
933 (2)
3055
2866
1444
1350
s
s
m
vw
1167 vw
1025 w
770 vw
2933
2963
1207
1047
695
s
s
m
s
s
2929 (30)
2973 (39)
1209 (2)
1047 (1)
690 (1)
2925
2949
1205
1043
696
803
s
s
m
s
s
vw
127.1
(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.
Cs
6-311++G**
C2v
cc-pVTZ
6-311++G**
cc-pVTZ
3057
2935
2879
1640
1479
1454
1300
1107
954
885
604
(23,187)
(55,183)
(31,240)
(3,250)
(3,43)
(2,136)
(1,21)
(0,136)
(1,57)
(1,100)
(14,7)
3068
2937
2881
1649
1481
1459
1303
1111
955
885
608
(23,186)
(56,173)
(31,218)
(2,143)
(2,57)
(1,143)
(1,21)
(0,129)
(1,50)
(0,100)
(12,7)
3064
2939
2913
1650
1485
1459
1303
1108
957
875
689
(23,187)
(46,168)
(1,282)
(4,206)
(4,41)
(0,129)
(1,18)
(0,118)
(1,35)
(0,100)
(0,5)
3066
2942
2896
1657
1486
1459
1306
1112
958
875
691
(24,187)
(44,154)
(2,267)
(3,125)
(3,56)
(0,138)
(1,19)
(0,119)
(1,31)
(0,100)
(0,11)
2924
1282
1131
955
872
385
(37,121)
(2,7)
(2,0)
(0,7)
(4,7)
(0,14)
2924
1287
1132
961
875
387
(37,120)
(2,7)
(1,0)
(0,7)
(4,7)
(0,21)
2913
1249
1139
958
889
370
(0,188)
(0,23)
(0,2)
(0,10)
(0,4)
(0,8)
2913
1253
1140
965
893
374
(0,184)
(0,25)
(0,3)
(0,5)
(0,3)
(0,11)
3043
2880
1460
1351
1291
1201
1014
899
768
(8,87)
(55,82)
(3,71)
(2,0)
(0,7)
(0,36)
(2,36)
(8,0)
(0,7)
3044
2883
1463
1358
1296
1205
1015
900
771
(8,87)
(54,75)
(2,71)
(2,0)
(0,7)
(0,29)
(2,29)
(7,0)
(0,7)
3040
2895
1464
1352
1287
1246
1018
891
773
(8,88)
(97,40)
(3,53)
(2,1)
(2,0)
(0,25)
(2,24)
(12,7)
(1,6)
3043
2896
1466
1360
1295
1247
1071
891
776
(8,87)
(95,33)
(2,56)
(1,3)
(1,0)
(1,19)
(2,18)
(11,5)
(1,4)
2916
2969
1207
1047
699
802
135
(5,66)
(44,87)
(2,50)
(8,7)
(39,14)
(1,7)
(0,14)
2918
2970
1209
1052
702
803
130
(4,61)
(43,84)
(2,43)
(7,7)
(31,21)
(1,7)
(0,7)
2910
2972
1201
1042
660
766
(33,3)
(43,74)
(2,40)
(9,2)
(46,8)
(8,9)
2910
2973
1204
1048
663
770
(35,2)
(43,74)
(2,38)
(8,3)
(37,16)
(7,11)
8
Vibrational Reassignments for Cyclopentene-d8
Observed *
Assignments
A1
1
2
3
4
5
6
7
8
9
10
11
A2
B1
B2
CD sym. str.
β-CD2 sym. str.
α-CD2 sym. str. (i.p.)
C=C str.
β-CD2 def.
α-CD2 def. (i.p.)
α-CD2 wag (i.p.)
CD in-plane bend (i.p.)
Ring str.
Ring breathing
Ring def.
12 α-CD2 antisym. str. (o.p.)
13 α-CD2 twist (o.p.)
14 β-CD2 twist
15 CD out-of-plane bend (o.p.)
16 α-CD2 rock (o.p.)
17 Ring twist
Vapor
IR 1
2310 s
2153 w
1580
1110
1070
750
853
1150
878
m
w
m
w
w
vw
m
868 w
921 w
724 m
18 CD antisym. str.
19 α-CD2 sym. str. (o.p.)
20 α-CD2 def. (o.p.)
21 CD in-plane bend (o.p.)
22 α-CD2 wag (o.p.)
23 β-CD2 wag
24 Ring str.
25 Ring str.
26 Ring def.
2276
2138
1062
709
1024
27
28
29
30
31
32
2200 s
2230 s
849 s
954 w
465 s
543 s
108.2
33
α-CD2 antisym. str. (i.p.)
β-CD2 antisym. str.
α-CD2 twist (i.p.)
α-CD2 rock (i.p.)
CD out-of-plane bend (i.p.)
β-CD2 rock
Ring puckering
m
m
m
w
vw
Vapor
Raman 1
Calculated (Scaled) at DFT-B3LYP
Cs
C2v
2305 (68)
2145 (100)
2100 (136)
1577 (50)
1113 (7)
1072 (2)
750 (7)
850 (7)
1158 (2)
878 (100)
6-311++G**
2314
(9,74)
2157
(18,75)
2126
(11,141)
1591
(6,205)
1109
(1,14)
1068
(1,18)
743
(1,14)
783
(0,32)
1148
(0,6)
869
(3,100)
682
(0,4)
cc-pVTZ
2315
(9,78)
2160
(18,67)
2128
(10,132)
1600
(4,143)
1110
(1,14)
1071
(1,19)
744
(1,13)
785
(0,38)
1149
(1,4)
871
(2,100)
681
(0,3)
6-311++G**
2313
(9,74)
2166
(23,84)
2132
(0,143)
1602
(6,76)
1110
(2,13)
1069
(0,16)
749
(1,16)
779
(0,33)
1149
(0,4)
863
(1,100)
643
(0,5)
cc-pVTZ
2314
(10,78)
2168
(22,77)
2135
(1,134)
1609
(5,123)
1110
(1,11)
1072
(0,18)
750
(0,14)
781
(0,33)
1148
(0,6)
865
(0,100)
645
(0,6)
2202 (15)
860 (5)
930 (1)
720 (6)
667
317 (2)
2191
887
926
725
658
318
(7,79)
(2,18)
(0,5)
(2,5)
(0,0)
(0,6)
2190
890
929
728
661
320
(7,79)
(1,19)
(0,4)
(1,3)
(0,0)
(2,9)
2185
888
926
730
670
305
(0,98)
(0,16)
(0,4)
(0,4)
(0,0)
(0,4)
2186
891
930
733
673
308
(0.96)
(0,16)
(0,2)
(0,4)
(0,0)
(0,7)
2268 (15)
2132 (20)
2268
2126
1060
705
1020
786
1124
1191
754
(3,44)
(37,29)
(2,14)
(7,5)
(1,0)
(0,23)
(1,4)
(0,9)
(1,1)
2270
2128
1062
707
1027
788
1122
1195
757
(3,44)
(38,24)
(2,14)
(6,2)
(1,0)
(0,20)
(1,3)
(0,10)
(1,0)
2267
2131
1058
705
1023
804
1114
1195
758
(3,44)
(47,24)
(2,11)
(9,2)
(1,0)
(0,19)
(1,5)
(1,9)
(1,1)
2268
2133
1059
706
1029
804
1113
1198
760
(3,44)
(46,19)
(1,9)
(8,2)
(1,0)
(0,14)
(1,6)
(1,9)
(1,3)
2193
2229
848
951
460
546
109
(22,34)
(22,41)
(6,27)
(0,10)
(16,5)
(13,4)
(0,3)
2192
2230
852
954
464
549
103
(23,31)
(22,40)
(5,29)
(0,8)
(13,3)
(10,8)
(0,1)
2185
2232
854
939
481
571
(24,3)
(20,36)
(9,9)
(0,7)
(24,3)
(5,3)
2186
2233
857
943
483
574
(24,2)
(20,37)
(8,9)
(0,5)
(19,6)
(4,4)
715
790 (7)
2202 (15)
2235 (30)
950 (1)
460 (1)
550 (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.
9
Vibrational Reassignments for 1-Cyclopentene-d1
Observed (*)
Assignments
A’
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
A”
21
22
23
24
25
26
27
28
29
30
31
32
33
Vapor
IR 1
Vapor
Raman 1
CH str.
β-CH2 sym. str.
α-CH2 sym. str.
α-CH2 sym. str
=C-D str.
C=C str.
β-CH2 def.
α-CH2 def.
α-CH2 def.
CH in-plane bend
α-CH2 wag
α-CH2 wag
β-CH2 wag
Ring str.
CD in-plane bend
Ring str.
Ring breathing
Ring str.
Ring def.
Ring def.
3065
2903
2865
2859
2294
1600
1470
1446
1435
1261
1300
1322
1116
1033
988
966
893
750
698
634
m
s
s
s
m
m
m
m
w
m
w
s
w
m
w
w
w
w
w
s
3066 (188)
2904 (122)
2879 (105)
2859 (224)
2290 (37)
1597 (79)
1472 (22)
1448 (32)
α-CH2 antisym. str.
α-CH2 antisym. str.
β-CH2 antisym. str.
α-CH2 twist
α-CH2 twist
β-CH2 twist
α-CH2 rock
CH out-of-plane bend
α-CH2 rock
β-CH2 rock
CD out-of-plane bend
Ring twist
Ring puckering
2939
2939
2962
1211
1137
1207
1044
s
s
s
s
w
w
s
2939 (126)
2924 (126)
2969 (60)
1202 (2)
1138
1257 (3)
1298 (10)
1327 (5)
1121 (1)
1029 (8)
978 (65)
952 (33)
899 (100)
750 (1)
708 (8)
630 (1)
1045
855 s
855 (1)
565 s
369 w
126
565 (1)
369 (3)
Calculated (Scaled) at DFT-B3LYP
C1
6-311++G**
Cs
cc-pVTZ
6-311++G**
cc-pVTZ
3054
2935
2880
2879
2291
1619
1479
1461
1455
1254
1299
1324
1286
1019
969
945
886
745
772
638
(15,138)
(53,188)
(54,80)
(32,242)
(6,54)
(4,270)
(3,42)
(3,76)
(2,136)
(1,21)
(1,13)
(2,4)
(2,11)
(3,39)
(1,86)
(2,49)
(2,100)
(3,6)
(1,7)
(6,5)
3056
2937
2882
2881
2293
1628
1481
1464
1458
1263
1303
1329
1288
1020
971
946
886
747
774
642
(16,138)
(54,178)
(53,74)
(31,220)
(7,55)
(3,177)
(2,62)
(2,77)
(1,154)
(1,15)
(1,17)
(2,6)
(2,14)
(3,38)
(2,85)
(2,38)
(2,100)
(3,15)
(1,8)
(4,6)
3051
2939
2895
2895
2288
1628
1484
1463
1455
1260
1302
1325
1240
1023
965
950
876
748
797
680
(15,139)
(45,172)
(25,225)
(73,99)
(6,54)
(5,229)
(4,41)
(3,53)
(0,124)
(1,16)
(1,12)
(2,4)
(0,31)
(3,29)
(2,76)
(2,35)
(1,100)
(3,12)
(3,11)
(0,5)
3054
2943
2897
2896
2291
1637
1486
1466
1459
1266
1305
1330
1242
1023
967
950
877
751
800
683
(16,139)
(43,157)
(12,246)
(85,57)
(7,56)
(4,153)
(3,66)
(2,60)
(0,153)
(1,14)
(1,13)
(2,9)
(0,21)
(3,31)
(2,64)
(1,33)
(1,100)
(3,13)
(3,10)
(0,6)
2925
2917
2969
1206
1131
1196
1043
897
860
812
563
370
137
(38,118)
(6,66)
(44,87)
(2,46)
(2,1)
(0,45)
(6,5)
(2,15)
(4,3)
(3,4)
(30,7)
(0,5)
(0,3)
2925
2918
2969
1208
1133
1199
1048
902
864
813
567
372
129
(38,117)
(4,61)
(43,84)
(2,43)
(1,2)
(0,38)
(6,5)
(2,17)
(3,18)
(3,6)
(25,15)
(0,10)
(0,4)
2913
2911
2972
1200
1139
1249
1038
910
861
744
578
355
(0,188)
(3,33)
(43,74)
(1,40)
(0,2)
(0,22)
(7,2)
(1,18)
(5,4)
(0,1)
(37,7)
(0,5)
2913
2910
2973
1203
1140
1253
1044
915
866
747
579
359
(0,184)
(35,2)
(43,74)
(1,41)
(0,3)
(0,27)
(6,5)
(1,13)
(4,10)
(0,4)
(30,12)
(0,12)
(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 1,2,3,3-Cyclopentene-d4
Assignments
A’
1 CD str.
2 β-CH2 sym. str.
3 α-CD2 sym. str.
4 α-CH2 sym. str
5 =C-D str.
6 C=C str.
7 β-CH2 def.
8 α-CH2 def.
9 α-CD2 def.
10 CD in-plane bend
11 α-CH2 wag
12 α-CD2 wag
13 β-CH2 wag
14 Ring str.
15 CD in-plane bend
16 Ring str.
17 Ring breathing
18 Ring str.
19 Ring def.
20 Ring def.
A”
21 α-CH2 antisym. str.
22 α-CD2 antisym. str.
23 β-CH2 antisym. str.
24 α-CH2 twist
25 α-CD2 twist
26 β-CH2 twist
27 α-CH2 rock
28 CD out-of-plane bend
29 α-CD2 rock
30 β-CH2 rock
31 CD out-of-plane bend
32 Ring twist
33 Ring puckering
Observed *
Vapor
Vapor
IR 1
Raman 1
2310 m
2313 (13)
2941 s
2941 (20)
2110 s
2100 (51)
2854 s
2861 (46)
2277 m
2265 (5)
1560 m
1580 (51)
1460 m
1467 (4)
1449 m
1452 (7)
1081 vw
1085 (4)
800 w
802 (3)
1286 w
1290 (1)
821 m
825 (7)
1027 w
1107 m
1100 (1)
715 vw
719
1143 w
910 m
910 (100)
985 vw
985 (2)
725 w
726 (1)
604 m
604 (1)
599 s
2904
2200
2964
1163
872
1226
1041
735
s
s
s
vw
s
s
w
858 m
502 s
337 w
120.0
2905 (20)
2194 (10)
2969 (30)
1160 (1)
875 (4)
1211 (1)
1045 (1)
733 (1)
860 (3)
500 (1)
338 (2)
Calculated (Scaled) at DFT-B3LYP
C1
Cs
6-311++G**
2314
(10,67)
2933
(52,165)
2127
(24,95)
2879
(41,167)
2268
(3,45)
1595
(4,195)
1474
(3,23)
1457
(2,72)
1081
(0,18)
796
(0,27)
1284
(1,9)
813
(1,18)
1309
(2,4)
1101
(3,8)
714
(2,3)
1151
(0,10)
901
(1,100)
973
(0,23)
767
(1,6)
603
(4,3)
cc-pVTZ
2315
(11,71)
2934
(52,156)
2128
(24,87)
2882
(41,152)
2270
(3,44)
1604
(4,141)
1477
(1,27)
1459
(1,82)
1084
(0,20)
798
(0,28)
1286
(1,10)
815
(1,22)
1314
(1,8)
1104
(2,6)
715
(2,4)
1153
(0,7)
903
(1,100)
974
(0,20)
769
(1,9)
607
(4,5)
6-311++G**
2312
(10,68)
2938
(43,146)
2134
(25,97)
2895
(49,167)
2266
(3,45)
1605
(6,191)
1480
(3,22)
1458
(1,74)
1082
(0,17)
792
(0,28)
1270
(1,13)
822
(1,30)
1310
(2,2)
1099
(3,8)
716
(7,4)
1164
(1,9)
894
(1,100)
979
(0,17)
769
(2,4)
661
(0,5)
cc-pVTZ
2314
(11,72)
2941
(41,134)
2135
(24,89)
2897
(48,156)
2268
(3,44)
1613
(5,132)
1483
(2,30)
1461
(1,77)
1085
(0,22)
793
(0,32)
1272
(1,18)
823
(1,27)
1315
(1,2)
1102
(2,8)
719
(7,4)
1167
(1,9)
897
(1,100)
978
(0,14)
771
(2,3)
664
(0,4)
2919
2192
2967
1163
872
1226
1038
733
703
848
502
337
128
2920
2191
2969
1166
875
1229
1042
736
706
849
506
338
120
2912
2187
2970
1160
874
1236
1031
723
666
841
511
323
2913
2187
2971
1162
878
1240
1037
729
669
844
514
327
(18,78)
(16,55)
(37,87)
(2,16)
(4,20)
(0,13)
(2,8)
(3,8)
(2,1)
(1,4)
(28,2)
(0,4)
(0,3)
(17,74)
(16,53)
(36,84)
(1,15)
(3,24)
(0,15)
(2,4)
(3,4)
(2,2)
(1,8)
(23,8)
(0,6)
(0,2)
(17,92)
(15,53)
(33,71)
(0,11)
(4,13)
(0,22)
(1,4)
(1,4)
(1,5)
(0,3)
(31,4)
(0,3)
(18,90)
(15,51)
(33,72)
(0,14)
(3,11)
(0,19)
(1,3)
(1,3)
(0,1)
(0,2)
(26,12)
(0,7)
(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.
11
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
12
Experimental (Liquid-phase) and Calculated Infrared
Spectra of Cyclopentene
5x
4x
13
Experimental (Liquid-phase) and Calculated Raman
Spectra of Cyclopentene
5x
10x
14
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.
15
Acknowledgments
•
•
•
The National Science Foundation.
The Robert A. Welch Foundation.
The Texas Advance Research Program.
16
Calculated Structure of Cyclopentene-d0
H
H 107.9o
H
1.088
1.087
110.8o
H
106.9o
1.091
106.5o
H
H
H
H
H
124.8o
(121.8o)
MP2/cc-pVTZ
C2v
1.338
(1.341)
H
H
H
o
1.093 108.2
107.2o
1.095
1.093
110.7o
113.0o
H
1.555
H
H
106.8o
107.3o
104.1o
H
H
1.099
H
H
1.509
1.343
H
111.4o
1.345
1.081
H
1.095
102.4o
112.5o
124.6o
H
1.544
105.0o
1.096
106.8o
1.081
Cs
Experimental values of GED
are shown in red 1
H
1.506 (1.519)
111.6o
(111.2o)
1.081
H
1.094
H
1.503
1.335
H
1.090
102.4o
112.6o
124.5o
1.540 (1.544)
105.1o
107.5o
(101.8o)
104.0o
H
1.090
113.8o
H
1.550
H
H
(104.8o)
107.0o
124.9o
MP2/6-311++G**
(1) Davis, M. I.; Mueche, T. W.; J. Phys. Chem., 1970, 74, 1104.
H
1.512
1.081
H
17
Experimental and Calculated Frequencies for Cyclopentene-d8
Observed 1
Assignments
A1
A2
B1
B2
Vapor
IR *
1
2
3
4
5
6
7
8
9
10
11
CD sym. str.
β-CD2 sym. str.
α-CD2 sym. str. (i.p.)
C=C str.
β-CD2 def.
α-CD2 def. (i.p.)
α-CD2 wag (i.p.)
CD in-plane bend (i.p.)
Ring str.
Ring breathing
Ring def.
12
13
14
15
16
17
α-CD2 antisym. str. (o.p.)
α-CD2 twist (o.p.)
β-CD2 twist
CD out-of-plane bend (o.p.)
α-CD2 rock (o.p.)
Ring twist
18
19
20
21
22
23
24
25
26
CD antisym. str.
α-CD2 sym. str. (o.p.)
α-CD2 def. (o.p.)
CD in-plane bend (o.p.)
α-CD2 wag (o.p.)
β-CD2 wag
Ring str.
Ring str.
Ring def.
2276
2138
1062
1150
954
868
1024
724
709
27
28
29
30
31
32
33
α-CD2 antisym. str. (i.p.)
β-CD2 antisym. str.
α-CD2 twist (i.p.)
α-CD2 rock (i.p.)
CD out-of-plane bend (i.p.)
β-CD2 rock
Ring puckering
2230 s
2200 s
878 m
849 s
543 s
465 s
108.2
2310 s
2153 w
1580
1110
1070
921
853
750
878
574
m
w
m
w
w
w
m
w ?
Vapor
Raman *
2305 (68)
2145 (100)
2100 (136)
1577 (50)
1113 (7)
1072 (2)
930 (1)
850 (7)
750 (7)
878 (100)
2202 (15)
790 (7)
667
317 (2)
m
m
m
vw
w
w
vw
m
w
2268 (15)
2132 (20)
1158 (2)
950 (1)
860 (5)
720 (6)
715
2235 (30)
2202 (15)
878
550 (1)
460 (1)
Calculated (Scaled) at DFT-B3LYP
Cs
C2v
Comments
from
Calculation
6-311++G**
2314
(9,74)
2157
(18,75)
2126
(11,141)
1591
(6,205)
1109
(1,14)
1068
(1,18)
926
(0,5)
783
(0,32)
743
(1,14)
869
(3,100)
682
(0,4)
cc-pVTZ
2315
(9,78)
2160
(18,67)
2128
(10,132)
1600
(4,143)
1110
(1,14)
1071
(1,19)
929
(0,4)
785
(0,38)
744
(1,13)
871
(2,100)
681
(0,3)
6-311++G**
2313
(9,74)
2166
(23,84)
2132
(0,143)
1602
(6,76)
1110
(2,13)
1069
(0,16)
926
(0,4)
779
(0,33)
749
(1,16)
863
(1,100)
643
(0,5)
cc-pVTZ
2314
(10,78)
2168
(22,77)
2135
(1,134)
1609
(5,123)
1110
(1,11)
1072
(0,18)
930
(0,2)
781
(0,33)
750
(0,14)
865
(0,100)
645
(0,6)
2191
786
1124
754
658
318
(7,79)
(0,23)
(1,4)
(1,1)
(0,0)
(0,6)
2190
788
1122
757
661
320
(7,79)
(0,20)
(1,3)
(1,0)
(0,0)
(2,9)
2185
804
1114
758
670
305
(0,98)
(0,19)
(1,5)
(1,1)
(0,0)
(0,4)
2186
804
1113
760
673
308
(0.96)
(0,14)
(1,6)
(1,3)
(0,0)
(0,7)
2268
2126
1060
1148
951
887
1020
725
705
(3,44)
(37,29)
(2,14)
(0,6)
(0,10)
(2,18)
(1,0)
(2,5)
(7,5)
2270
2128
1062
1149
954
890
1027
728
707
(3,44)
(38,24)
(2,14)
(1,4)
(0,8)
(1,19)
(1,0)
(1,3)
(6,2)
2267
2131
1058
1149
939
888
1023
730
705
(3,44)
(47,24)
(2,11)
(0,4)
(0,7)
(0,16)
(1,0)
(0,4)
(9,2)
2268
2133
1059
1148
943
891
1029
733
706
(3,44)
(46,19)
(1,9)
(0,6)
(0,5)
(0,16)
(1,0)
(0,4)
(8,2)
9
30
13
2229
2193
1191
848
546
460
109
(22,41)
(22,34)
(0,9)
(6,27)
(13,4)
(16,5)
(0,3)
2230
2192
1195
852
549
464
103
(22,40)
(23,31)
(0,10)
(5,29)
(10,8)
(13,3)
(0,1)
2232
2185
1195
854
571
481
----
(20,36)
(24,3)
(1,9)
(9,9)
(5,3)
(24,3)
2233
2186
1198
857
574
483
----
(20,37)
(24,2)
(1,9)
(8,9)
(4,4)
(19,6)
28
27
25
29
32
31
14
7
23
24
26
15
21
(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.
18