CCCBDB listing of experimental data page 2

Experimental data for C₅H₈ (1,3-Butadiene, 2-methyl-)

Other names
1,3-Butadiene, 2-methyl-; β-Methylbivinyl; 2-Methyl-1,3-butadiene; 2-Methylbuta-1,3-diene; 2-Methylbutadiene; Isopentadiene; Isoprene; Isoprene, inhibited; beta-Methylbivinyl;

Other names

1,3-Butadiene, 2-methyl-; β-Methylbivinyl; 2-Methyl-1,3-butadiene; 2-Methylbuta-1,3-diene; 2-Methylbutadiene; Isopentadiene; Isoprene; Isoprene, inhibited; beta-Methylbivinyl;

INChI	INChIKey	SMILES	IUPAC name
InChI=1S/C5H8/c1-4-5(2)3/h4H,1-2H2,3H3	RRHGJUQNOFWUDK-UHFFFAOYSA-N	C=C(C)C=C	Isoprene

INChI

INChIKey

SMILES

IUPAC name

InChI=1S/C5H8/c1-4-5(2)3/h4H,1-2H2,3H3

RRHGJUQNOFWUDK-UHFFFAOYSA-N

C=C(C)C=C

Isoprene

State	Conformation
¹A^'	CS

State

Conformation

¹A^'

Enthalpy of formation (Hfg), Entropy, Integrated heat capacity (0 K to 298.15 K) (HH), Heat Capacity (Cp)

Property	Value	units	Reference
Hfg(298.15K)	75.75	kJ mol^-1	TRC
Hfg(0K)	96.27	kJ mol^-1	TRC
Entropy (298.15K)	314.67	J K^-1 mol^-1	TRC
Integrated Heat Capacity (0 to 298.15K)	18.60	kJ mol^-1	TRC
Heat Capacity (298.15K)	102.69	J K^-1 mol^-1	TRC

Information can also be found for this species in the NIST Chemistry Webbook

Vibrational levels (cm^-1) vibrations

Mode Number	Symmetry	Frequency			Intensity			Comment	Description
Mode Number	Symmetry	Fundamental(cm^-1)	Harmonic(cm^-1)	Reference	(km mol^-1)	unc.	Reference	Comment	Description
1	A'	3095		1974sve/kov
2	A'	3095		1974sve/kov
3	A'	3000		1974sve/kov
4	A'	3000		1974sve/kov
5	A'	3000		1974sve/kov
6	A'	2984		1974sve/kov
7	A'	2904		1974sve/kov
8	A'	1638		1974sve/kov
9	A'	1607		1974sve/kov
10	A'	1464		1974sve/kov
11	A'	1420		1974sve/kov
12	A'	1389		1974sve/kov
13	A'	1363		1974sve/kov
14	A'	1313		1974sve/kov
15	A'	1303		1974sve/kov
16	A'	1072		1974sve/kov
17	A'	1012		1974sve/kov
18	A'	953		1974sve/kov
19	A'	770		1974sve/kov
20	A'	530		1974sve/kov
21	A'	396		1974sve/kov
22	A'	196		1974sve/kov
23	A"	2949		1974sve/kov
24	A"	1451		1974sve/kov
25	A"	1034		1974sve/kov
26	A"	991		1974sve/kov
27	A"	907		1974sve/kov
28	A"	907		1974sve/kov
29	A"	757		1974sve/kov
30	A"	615		1974sve/kov
31	A"	290		1974sve/kov
32	A"	153		1974sve/kov

Calculated vibrational frequencies for C₅H₈ (1,3-Butadiene, 2-methyl-).
Gas-phase IR spectra can be found in the NIST Chemistry Webbook here.

Rotational Constants (cm^-1)

See section I.F.4 to change rotational constant units

A	B	C	reference	comment
0.28443	0.13928	0.09514	NISThydrocarbon

Calculated rotational constants for C₅H₈ (1,3-Butadiene, 2-methyl-).

Product of moments of inertia
1271064	amu³Å⁶		5.820164176722E-114	gm³ cm⁶

Geometric Data
picture of 1,3-Butadiene, 2-methyl-

Point Group C_s

Internal coordinates
distances (r) in Å, angles (a) in degrees, dihedrals (d) in degrees

Description	Value	unc.	Connectivity				Reference	Comment
Description	Value	unc.	Atom 1	Atom 2	Atom 3	Atom 4	Reference	Comment
rCC	1.340		1	2			1987Kuchitsu(II/15)
rCC	1.463		2	3			1987Kuchitsu(II/15)	both C's have =
rCC	1.512		2	5			1987Kuchitsu(II/15)	to methyl C
rCH	1.076		1	6			1987Kuchitsu(II/15)	average, not methyl C
rCH	1.110		5	11			1987Kuchitsu(II/15)	average, methyl C
aCCC	121.4		1	2	3		1987Kuchitsu(II/15)	middle C has methyl C
aCCC	127.3		2	3	4		1987Kuchitsu(II/15)	middle C is CH
aCCC	121		1	2	5		1987Kuchitsu(II/15)	end C to methyl C
aHCC	124.3		2	1	6		1987Kuchitsu(II/15)	to CH2 groups
aHCC	123.4		4	3	8		1987Kuchitsu(II/15)	to CH group from end
aHCC	109.1		2	5	11		1987Kuchitsu(II/15)	to CH3 group
aHCH	109.84		11	5	12		1987Kuchitsu(II/15)	from symmetry, methyl group

Cartesians

Atom	x (Å)	y (Å)	z (Å)
C1	0.5485	1.7492	0.0000
C2	0.0000	0.5266	0.0000
C3	0.8273	-0.6800	0.0000
C4	0.4073	-1.9525	0.0000
C5	-1.5013	0.3467	0.0000
H6	1.6077	1.9386	0.0000
H7	-0.0142	2.6663	0.0000
H8	1.8660	-0.3990	0.0000
H9	-0.6268	-2.2497	0.0000
H10	1.0614	-2.8069	0.0000
H11	-1.9867	1.3449	0.0000
H12	-1.7995	-0.2173	0.9084
H13	-1.7995	-0.2173	-0.9084

Atom - Atom Distances bond lengths

Distances in Å

	C1	C2	C3	C4	C5	H6	H7	H8	H9	H10	H11	H12	H13
C1		1.3400	2.4452	3.7044	2.4837	1.0760	1.0760	2.5201	4.1681	4.5849	2.5673	3.1946	3.1946
C2	1.3400		1.4630	2.5124	1.5120	2.1397	2.1397	2.0830	2.8462	3.4984	2.1486	2.1486	2.1486
C3	2.4452	1.4630		1.3400	2.5448	2.7324	3.4505	1.0760	2.1397	2.1397	3.4668	2.8176	2.8176
C4	3.7044	2.5124	1.3400		2.9881	4.0720	4.6380	2.1309	1.0760	1.0760	4.0748	2.9506	2.9506
C5	2.4837	1.5120	2.5448	2.9881		3.4928	2.7553	3.4488	2.7397	4.0635	1.1100	1.1100	1.1100
H6	1.0760	2.1397	2.7324	4.0720	3.4928		1.7778	2.3518	4.7471	4.7768	3.6432	4.1330	4.1330
H7	1.0760	2.1397	3.4505	4.6380	2.7553	1.7778		3.5961	4.9540	5.5779	2.3742	3.5110	3.5110
H8	2.5201	2.0830	1.0760	2.1309	3.4488	2.3518	3.5961		3.1047	2.5387	4.2290	3.7807	3.7807
H9	4.1681	2.8462	2.1397	1.0760	2.7397	4.7471	4.9540	3.1047		1.7778	3.8432	2.5162	2.5162
H10	4.5849	3.4984	2.1397	1.0760	4.0635	4.7768	5.5779	2.5387	1.7778		5.1505	3.9643	3.9643
H11	2.5673	2.1486	3.4668	4.0748	1.1100	3.6432	2.3742	4.2290	3.8432	5.1505		1.8167	1.8167
H12	3.1946	2.1486	2.8176	2.9506	1.1100	4.1330	3.5110	3.7807	2.5162	3.9643	1.8167		1.8167
H13	3.1946	2.1486	2.8176	2.9506	1.1100	4.1330	3.5110	3.7807	2.5162	3.9643	1.8167	1.8167

Calculated geometries for C₅H₈ (1,3-Butadiene, 2-methyl-).

Experimental Bond Angles (degrees) from cartesians

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C3	121.400	C1	C2	C5	121.000
C2	C1	H6	124.300	C2	C1	H7	124.300
C2	C3	C4	127.300	C2	C3	H8	109.300
C2	C5	H11	109.100	C2	C5	H12	109.100
C2	C5	H13	109.100	C3	C2	C5	117.600
C3	C4	H9	124.300	C3	C4	H10	124.300
C4	C3	H8	123.400	H6	C1	H7	111.400
H9	C4	H10	111.400	H11	C5	H12	109.840
H11	C5	H13	109.840	H12	C5	H13	109.840

Bond descriptions

Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond

Bond Type	Count
H-C	8
C-C	2
C=C	2

Connectivity

Atom 1	Atom 2
C1	C2
C1	H6
C1	H7
C2	C3
C2	C5
C3	C4
C3	H8
C4	H9
C4	H10
C5	H11
C5	H12
C5	H13

Electronic energy levels (cm^-1)

Energy (cm^-1)	Degeneracy	reference	description
0	1		¹A^'

Ionization Energies (eV)

Ionization Energy	I.E. unc.	vertical I.E.	v.I.E. unc.	reference
8.860	0.020	8.860		webbook

Dipole, Quadrupole and Polarizability
Electric dipole moment dipole

State	Config	State description	Conf description	Exp. min.	Dipole (Debye)				Reference	comment	Point Group	Components
State	Config	State description	Conf description	Exp. min.	x	y	z	total	Reference	comment	Point Group	dipole	quadrupole
1	1	¹A^'	C_s	True	0.250	0.035		0.252	NISThydrocarbon	x=b, y=a	C_s	2	3

Experimental dipole measurement abbreviations: MW microwave; DT Dielectric with Temperature variation; DR Indirect (usually an upper limit); MB Molecular beam
Calculated electric dipole moments for C₅H₈ (1,3-Butadiene, 2-methyl-).
Electric quadrupole moment

State	Config	State description	Conf description	Exp. min.	Quadrupole (D Å)			Reference	comment	Point Group	Components
State	Config	State description	Conf description	Exp. min.	xx	yy	zz	Reference	comment	Point Group	dipole	quadrupole
1	1	¹A^'	C_s	True	1.700	3.300	-5.000	1971Fly/Ben:225	Qxx=1.7+-2.2, Qyy=3.3+-2.3, Qzz=-5.0+-3.2	C_s	2	3

Calculated electric quadrupole moments for C₅H₈ (1,3-Butadiene, 2-methyl-).

References
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squib	reference	DOI
1971Fly/Ben:225	WH Flygare, RC Benson "The molecular Zeeman effect in diamagnetic molecules and the determination of molecular magnetic moments (g values), magnetic susceptibilities, and molecular quadrupole moments" Mol. Phys. 1971, 20 (2), 225-250	10.1080/00268977100100221
1974sve/kov	L.M. Sverdlov, M. A. Kovner, E. P. Krainov, "Vibrational Spectra of Polyatomic Molecules" Wiley, New York 1974
1987Kuchitsu(II/15)	Kuchitsu (ed.), Landolt-Bornstein: Group II: Atomic and Molecular Physics Volume 15: Structure Data of Free Polyatomic Molecules. Springer-Verlag, Berlin, 1987.
NISThydrocarbon	NIST Hydrocarbon spectral database (http://www.physics.nist.gov/PhysRefData/MolSpec/Hydro/index.html)	10.18434/T4PC70
TRC	Frenkel, M; Marsh, K.N.; Wilhoit, R.C.; Kabo, G.J.; Roganov, G.N.,Thermodynamics of Organic Compounds in the Gas State,Thermodynamics Research Center, College Station, TX, 1994
webbook	NIST Chemistry Webbook (http://webbook.nist.gov/chemistry)	10.18434/T4D303

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Experimental data for C5H8 (1,3-Butadiene, 2-methyl-)

Experimental data for C₅H₈ (1,3-Butadiene, 2-methyl-)