Diacetylene | SSHADE

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Molecule

Name: Diacetylene

Name and identifiers

IUPAC name: Buta-1,3-diyne
Secondary names: Butadiyne, 1,3-Butadiyne, Biacetylene, C4H2
InChI: InChI=1S/C4H2/c1-3-4-2/h1-2H
InChI key: LLCSWKVOHICRDD-UHFFFAOYSA-N
CAS number: 460-12-8
Comments: natural $C_4H_2$

Structure and atomic composition

Formula: $C_4H_2$
Chemical formula: C4H2
Structural formula: [HC]#CC#[CH]
Charge: 0
Unpaired electrons: 0

	Atom	Name	Number
	$C$	Carbon	4
	$H$	Hydrogen	2

Relations

no

Isotopic composition

Isotope mixture type: terrestrial abundance

Nuclear spin isomers

Spin type: unique

Molar mass: 50.06 $g/mol$
State STP: gas
State NTP: gas
Protic: protic
Polarity: nonpolar
Dipole: 0.0 $D$

Fundamental vibration modes

Molecule symmetry

Dinfh

Case

linear-polyatomic

Vibrations number

9

Vibrations

Label	Mode	Bond	Symmetry	Degeneracy	Fundamental frequency	Observed frequency	Observed frequency	Harmonic frequency	Activity IR	Activity Raman	Strength	Comments
V4	stretching asym.	$\equiv C-H$	$\Sigma+$	no		3332.8			active	inactive	vs
V1	stretching sym.	$\equiv C-H$	$\Sigma+$	no		3293.0			inactive	active	ia	Raman: vw, in liquid
V2	stretching sym.	$-C\equiv C-$	$\Sigma+$	no		2184.0			inactive	active	ia	Raman: vs
V5	stretching asym.	$-C\equiv C-$	$\Sigma+$	no		2019.8			active	inactive	m
V3	stretching	$\equiv C-C \equiv$	$\Sigma+$	no		874.0			inactive	active	ia	Raman: w
V8	bending out-p	$-C \equiv C-H$	$\Pi$	double		628.0			active	inactive	vs
V6	bending sym.	$-C \equiv C-H$	$\Pi$	double		627.0			inactive	active	ia	Raman: m
V7	bending sym.	$-C\equiv C-C\equiv$	$\Pi$	double		482.0			inactive	active	ia	Raman: s
V9	bending out-p	$-C\equiv C-C\equiv$	$\Pi$	double		220.1			active	inactive	s

Comments

Vibrations of the main isotope:

$^{12}C_4~^1H_2$ . IR data from Jolly et al. 2014

Chemical functions and bonds

Chemical functions

	Function	Number
	$R-C\equiv C-R$	1

Chemical bonds

	Bond	Number
	$\equiv C-C \equiv$	1
	$-C\equiv C-$	2
	$\equiv C-H$	2