C4H4   -   1-Butene-3-yne

Rotational constants for the ground, the ν13 = 1 and the ν18 = 1 states of 1-butene-3-yne and 1-butene-3-yne-4d
Parameter CH2CHCCH CH2CHCCD Ref.
Ground State ν13 = 1 ν18 = 1 Ground State ν13 = 1 ν18 = 1
A [MHz] 50 308.(55) 49 274.(59) 51 676.(53) 49 393.(34) 48 337.(36) 50 866.(49) 80032
B [MHz] 4744.9317(77) 4763.276(11) 4747.7146(81) 4403.9538(40) 4420.6331(43) 4406.1168(51)
C [MHz] 4329.7899(77) 4337.5385(99) 4338.6433(83) 4037.8007(40) 4044.8607(43) 4045.6294(51)
DJ [kHz] 1.93(22) 2.17(28) 1.86(21) 1.56(11) 1.60(12) 1.60(14)
DJK [kHz] -83.22(67) -70.90(86) -93.19(64) -77.35(34) -66.43(46) -88.66(44)
Electric Dipole Moment
µa [C · m]
    µa [D]		 0.744(67) x 10-30
    0.223(20)		   0.687(27) x 10-30
    0.206(8)		   70061
µb [C · m]
    µb [D]		 0.07 x 10-30
    0.02		 0.07 x 10-30
    0.02

 

 

Rotational constants for the ground state of 1-butene-3-yne
Parameter CH2 = CHC ≡ CH Ref.
A″ [MHz] 50 291.4(107) a
B″ [MHz] 4744.872(5)
C″ [MHz] 4329.687(5)
τ1 [kHz] 0.310 29(46)
τ2 [kHz] 0.018 73(37)
τ3 [kHz] 1.119(88) b
τbbbb [kHz] -0.010 55(39)
τcccc [kHz] -0.004 49(36)
 
a J. Phys. Chem. Ref. Data 18(3), 1245-1524 (1989).
 
b The value of τ3 is derived from the planarity conditions.

 

 

C4H4   -   Methylene Cyclopropene

Molecular constants for methylene cyclopropene and its 13C isotopic forms
Parameter _CHCH_CCH2 _13CHCH_CCH2 _CHCH_C13CH2 Ref.
Rotational Constants
A [MHz] 29 294.60(103) 28 618.83(1019) 29 322.21(1599) 86013
B [MHz] 7154.36(6) 7055.65(2) 6903.74(5)
C [MHz] 5744.23(6) 5653.55(2) 5581.52(5)
Δ (u Å2) 0.0894 0.1048 0.1059
Electric Dipole Moment
µb [C · m]
    µb [D]		 6.34(7) x 10-30
    1.90(2)

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