Ethyne | SSHADE

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Molecule

Name: Ethyne

Name and identifiers

IUPAC name: Ethyne
Secondary names: Acetylene, C2H2
InChI: InChI=1S/C2H2/c1-2/h1-2H
InChI key: HSFWRNGVRCDJHI-UHFFFAOYSA-N
CAS number: 74-86-2

Structure and atomic composition

Formula: $C_2H_2$
Chemical formula: C2H2
Structural formula: $[CH]#[CH]$
Charge: 0

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

Relations

no

Isotopic composition

Isotope mixture type: terrestrial abundance

Nuclear spin isomers

Spin type: equilibrated
Spin quantum numbers: 0, 1

Molar mass: 26.0373 $g/mol$
State STP: gas
Protic: aprotic
Polarity: nonpolar
Dipole: 0.0 $D$

Fundamental vibration modes

Molecule symmetry

Dinfh

Case

linear-polyatomic

Vibrations number

5

Vibrations

Label	Mode	Bond	Symmetry	Degeneracy	Fundamental frequency	Observed frequency	Observed frequency	Harmonic frequency	Activity IR	Activity Raman	Strength	Comments
v1	stretching sym.	$\equiv C-H$		no		3373.7			inactive	active	s
v2	stretching sym.	$-C\equiv C-$		no		1973.8			inactive	active	vs
v3	stretching asym.	$\equiv C-H$		no		3294.9	3281.9		active	inactive		Fermi resonance with v2+v4+v5 mode
v4	bending	$>C=C(-)-H$		double		611.8			inactive	active	vw
v5	bending	$>C=C(-)-H$		double		730.3			active	inactive	vs	Vibrations of the main isotope: $^{12}C_2H_2$ . Data from NIST Chemistry WebBook

Publications

Shimanouchi, 1972, Natl. Bur. Stand., 39, 1 - 160

Chemical functions and bonds

Chemical functions

	Function	Number
	$R\equiv CH$	2

Chemical bonds

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