C4H8   -   1-Butene

Molecular constants for the ground vibrational state of cis-1-butene and skew-1-butene

Parameter cis-1-butene skew-1-butene Ref.
Rotational Constants
A″ [MHz] 15 302.559(25) 22557.431(33) a
B″ [MHz] 5574.9560(64) 4156.123(13)
C″ [MHz] 4303.1269(75) 4056.202(13)
τ1 [kHz] b 0.2425(66)
τ2 [kHz] -4.3111(4) 28.50(221)
τ3 [kHz] 0.37(3) 6.86(150)
τaaaa [kHz] -0.103(21) b
τbbbb [kHz] -21.528(804) -8.422(2053)
τcccc [kHz] -5.093(1009) -15.033(2020)
Electric Dipole Moment
µa [C · m]
    µa [D]
1.228(13) x 10-30
    0.368(4)
1.151(23) x 10-30
    0.345(7)
68043
µb [C · m]
    µb [D]
0.791(20) x 10-30
    0.237(6)
0.270(37) x 10-30
    0.081(11)
µc [C · m]
    µc [D]
  0.197(53) x 10-30
    0.059(16)
 
a J. Phys. Chem. Ref. Data 18(3), 1245-1524 (1989).
 
b Not determinable. Comments: An error in reference [68043] has been corrected. The 111-000 transition frequency for skew-1-butene should be 26 713.84 rather than 26 613.84.

 

 

Molecular constants for excited vibrational states of 1-butene

Parameter cis-1-butene skew-1-butene Ref.
CC Torsion υ=1
A [MHz] 15338.60 22545.89 68043
B [MHz] 5539.25 4166.65
C [MHz] 4301.14 4068.25
CC Torsion υ=2
A [MHz] 15392.70 22542.82 a
22543.99 a
B [MHz] 5516.67 4177.15
C [MHz] 4294.62 4078.45
Methyl Torsion υ=1
A [MHz] 15274.57 22571.19
B [MHz] 5547.22 4150.52
C [MHz] 4290.53 4052.51
Methyl Torsion υ=2
A [MHz] 15274.57  
B [MHz] 5519.95
C [MHz] 4278.05
Skeletal Bend υ=1
B [MHz]   4148.85
C [MHz] 4043.08
 
a The two values refer to the doublet components for the J(1,J-1) and J(0,J).

 

 

Rotational constants for deuterated and 13 isotopic forms of 1-butene

Species a Parameter cis-1-butene skew-1-butene Ref.
1-d A [MHz] 15 154.73 22 159.8 68043
B [MHz] 5197.01 3924.04
C [MHz] 4063.89 3823.00
2-d A [MHz] 14 279.29 21 083.7
B [MHz] 5518.02 4006.04
C [MHz] 4185.50 3924.16
3-d A [MHz] 14 381.80 20477.
B [MHz] 5456.94 4108.80
C [MHz] 4159.06 4002.65
4-d A [MHz] 14 261.64 20342.4
B [MHz] 5474.89 4113.03
C [MHz] 4207.41 3981.11
5-d A [MHz]   20592.9
B [MHz] 4143.13
C [MHz] 3993.69
6-d A [MHz] 15 233.15  
B [MHz] 5209.19 3925.09
C [MHz] 4077.42 3837.82
7-d A [MHz] 14367.82  
B [MHz] 5441.16 4023.63
C [MHz] 4197.86 3902.19
8-d B [MHz]   4047.80
C [MHz] 3946.61
1,1-d2 A [MHz] 14 187.125(11) 20 858.(200) 81038
B [MHz] 5148.606(4) 3795.009(34) 80033
C [MHz] 3962.463(4) 3710.571(34)
1,3-d2 A [MHz] 14197.37 20173. 68043
B [MHz] 5105.83 3880.38
C [MHz] 3937.88 3780.03
2,3-d2 B [MHz]   3980.54
C [MHz] 3857.63
4,5-d2 B [MHz] 4081.14
C [MHz] 3939.25
4,6-d2 B [MHz] 3886.88
C [MHz] 3774.58
4,7-d2 B [MHz] 3974.43
C [MHz] 3844.13
4,8-d2 B [MHz] 4024.61
C [MHz] 3861.02
5,6-d2 B [MHz] 3915.52
C [MHz] 3782.18
5,7-d2 B [MHz] 4016.84
C [MHz] 3839.49
5,8-d2 B [MHz] 4021.58
C [MHz] 3901.38
d8 A [MHz] 10 597.801(8)   81038
B [MHz] 4412.849(6) 3313.17 79033
C [MHz] 3374.997(6) 3221.16
1-13C A [MHz] 15 148.537(16)   81038
B [MHz] 5442.077(3) 4044.66 79033
C [MHz] 4211.638(3) 3952.64
4-13C B [MHz]   4053.72 79033
C [MHz] 3956.64
 
a See references [68043] and 79033] for hydrogen atom numbering.

 

 

Centrifugal distortion constants for isotopic forms of  1-butene

Parameter cis-1,1-d2 cis-1-13C cis-1-d8 Ref. skew-1,1-d2 Ref.
ΔJ [kHz] 2.959(56) 3.37(6) 2.01(12) 81038 3.13(24) 80033
ΔJK [kHz] -7.94(32) -9.90(27) -4.16(15) -53.89(72)
ΔK [kHz] 24.8(12) 31.7(34) 11.6(10)  
δJ [kHz] 0.888(25) 0.991(14) 0.590(10) -0.82(40) 80033
δK [kHz] 3.67(7) 4.15(36) 1.06(22)  

 


 

C4H8   -   cis-2-Butene

Molecular constants for cis-2-butene in the ground state

Parameter CH3CHCHCH3 Ref. Parameter CH3CHCHCH3 Ref.
A1A1 State Rigid Rotor A1A1 State
Rotational Constants
A [MHz] 16086.12 70067 A [MHz] 16059.61 16085.76 68049
B [MHz] 5144.33 B [MHz] 5139.15 5144.61
C [MHz] 4087.93 C [MHz] 4088.16 4088.16
Internal Rotational Constants
Iα (u Å2) 3.130 70067 Iα (u Å2) 3.194 a   68049
λa 0.5850(12) λa 35.0° a
λb 0.8111(9)  
r 0.94504 α 0.058 199 b
q 0.0131 β 0.026 598 b
s 20.39(11) s 20.332
F [GHz] 170.937 F [GHz] 167.54
V3 (cm-1) 261.7(14) V3 (cm-1) 255.8
Electric Dipole Moment
µb [C · m]
    µb [D]
0.844(17) x 10-30
    0.253(5)
70067 µb [C · m]
    µb [D]
0.857(33) x 10-30
    0.257(10)
  68049
 
a Assumed.
 
b The values are defined as α = (Iα/Ia) sinθ, β = (Iα/Ib) cosθ.

Comments: The 716 - 707 transition reported at 31 829.11 MHz deviates by about 3 MHz in the analysis and was not fit.

 

 

Molecular constants for sym-CH2DCHCHCH3asy-CH2DCHCHCH3, and CH3CDCDCH3

Parameter sym-CH2DCHCHCH3
Value
asy-CH2DCHCHCH3
Value
CH3CDCDCH3
Value
Ref.
Rotational Constants
A-C (A1) [MHz] 11 040.37 11 681.12 10 033.99 70067
B-C (A1) [MHz] 1101.06 938.69 1155.42
A-C (A2) [MHz]   11 672.24  
B-C (A2) [MHz] 937.77
Internal Rotational Constants a
λa 0.5538(16) 0.5684(28) 0.5883(54)
λb 0.8259(12) 0.8228(20) b 0.8086(39)
Iα (u Å2) 3.130 3.130 3.130
r 0.94904 0.94823 0.95002
F [GHz] 170.184 170.329 170.026
s 20.42(2) 20.66(4) 20.96(7)
V3 (cm-1) 260.9(3) 264.2(5) 267.6(9)
 
a Values with no uncertainties are calculated from other constants.
 
b Value for λc = 0.0034 was included.

 

 

Molecular constants for CH3CDCHCH3

Parameter Value Ref.
Rotational Constants
A-C (A1A1) [MHz] 10 942.28 70067
B-C (A1A1) [MHz] 1107.63
Internal Rotational Constants a
  A1 State A2 State
λa -0.5700(164) 0.6118(124)
λb 0.8216(114) 0.7910(96)
Iα (u Å2) 3.130 3.130
r 0.948 83 0.948 83
q 0.011 78 0.011 78
F [GHz] 170.248 170.248
s 20.68(11) 20.61(11)
x -0.012 45  
V3 (cm-1) 264.4(14) 264.4(14)
 
a Values without uncertainties are calculated from other constants.

 

 

Molecular constants for d8 and d6 cis-2-butene

Parameter CD3CDCDCD3 CD3CHCHCD3 Ref.
Rotational Constants
A [MHz] 11 136.1(3) 12 684.2(2) 79039
B [MHz] 3997.05(14) 4008.11(4)
C [MHz] 3170.96(11) 3346.45(4)
Internal Rotational Constants
Iα (u Å2) 5.83(20) 5.98(20)
θ 54.08(12) 54.27(1)
s 40.34(10) 39.31(8)
V3 (cm-1) 284.(11) 272.(11)

 


 

C4H8   -   Isobutylene

Molecular constants for isobutylene (2-methl propene) in the ground and torionally excited states

  (CH3)2C=CH2  
Parameter Ground State υt = 11 State υt = 12 State Ref.
Rotational Constants a
A [MHz] 9133.31(3) 9132.01(3) 9140.61(3) 75058
B [MHz] 8381.80(3) 8369.09(3) 8353.22(3)
C [MHz] 4615.97(2) 4613.46(2) 4613.41(2)
ΔJK [kHz] -16.70(7)  
ΔJ [kHz] 7.88(46)
δJ [kHz] -65.3(30)
δK [kHz] -19.385(48)
Internal Rotational Constants
Iα (u Å2) 3.18(1) 3.18 b
θ 58.21(6)° 58.21 b
V3 (cm-1) 759.8(32) 767.9(35)
V12 (cm-1)   -74.(11)
Δ0 [MHz] -9.659(58)  
ρ 0.056 20(20)
β [rad] 0.5172(12)
Electric Dipole Moment
µb [C · m]
    µb [D]
1.678(30) x 10-30
    0.503(9)
  61014
 
a Representation IIIr was used.
 
b Values fixed.

 

 

Rotational analysis of isobutylene AA state

Parameter AA State Ref.
A″ [MHz] 9133.392(35) a
B″ [MHz] 8381.846(35)
C″ [MHz] 4615.966(35)
τ1 [kHz] -0.021(25)
τ2 [kHz] -0.0054(84)
τ3 [kHz] 0.60(25) b
τaaaa [kHz] -0.028(8)
τbbbb [kHz] -0.029(8)
τcccc [kHz] 0.0041(85)
 
a J. Phys. Chem. Ref. Data 18(3), 1245-1524 (1989).
 
b The value of τ3 is fixed by setting R6 = 0.

 

 

Rotational constants for deuterated and 13C isotopic species of isobutylene

Species A [MHz] B [MHz] C [MHz] Ref.
sym-CH2DCH3CCH2 9132.59 7788.98 4431.05 61014
asy-CH2DCH3CCH2 8819.46 7981.08 4469.59
(CH3)2CCHD 8693.49 8114.67 4422.67 63027
(CH3)2C13CH2 8810.08 8381.73 4531.84
CH313CH3CCH2 9074.31 8149.00 4529.72

 


 

C4H8   -   Methylcyclopropane

Molecular constants for methylcyclopropane

Parameter CH3_CHCH2_CH2 Ref.
Rotational Constants
A″ [MHz] 15 503.225(33) a
B″ [MHz] 6363.4072(78)
C″ [MHz] 5586.4839(69)
τ1 [kHz] -0.0077(53)
τ2 [kHz] -0.0017(15)
τ3 b [kHz] 0.147(58)
τaaaa [kHz] -0.112(41)
τbbbb [kHz] -0.0028(6)
Internal Rotation Barrier
V3 (cm-1) 1001.(18) 68048
Dipole Moment
µa [C · m]
    µa [D]
0.324(3) x 10-30
    0.097(1)
68048
µc [C · m]
    µc [D]
0.334(17) x 10-30
    0.100(5)
 
a J. Phys. Chem. Ref. Data 18(3), 1245-1524 (1989).
 
b The value of τ3 is fixed by setting R6 = 0.

 


 

C4H8   -   Cyclobutane-d1

Molecular constants for cyclobutane-d1

Parameter Equatorian Axial Ref.
A [MHz] 10 617.908(17) 10 377.613(18) 87024
B [MHz] 9817.535(17) 9975.708(18)
C [MHz] 6050.794(17) 6193.449(18)
ΔJ [kHz] 4.3(22) 5.3(20)
ΔJK [kHz] -3.18(89) -4.4(12)
ΔK [kHz] 6.04(66) 6.25(83)
δJ [kHz] 0.79(13) 0.95(19)
δK [kHz] 1.31(37) 0.65(45)
HKJ [Hz] -0.0079(6) -0.014(7)
Electric Dipole Moment
µa [C · m]
    µa [D]
0.0143(47) x 10-30
    0.0043(14)
  87024
µc [C · m]
    µc [D]
   0.0143(47) x 10-30
    0.0043(14)


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