Microwave spectrum of formamide--water and formamide--methanol complexes

Journal Article · Fri Jan 15 04:00:00 EST 1988 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.454151· OSTI ID:5513434

Lovas, F J; Suenram, R D; Fraser, G T; Gillies, C W; Zozom, J

The microwave spectra of the formamide--water and formamide--methanol complexes have been investigated with a pulsed beam Fabry--Perot cavity Fourier transform microwave spectrometer. The observed hyperfine structure due to the /sup 14/N nuclear quadrupole interaction was used to assign the rotational transitions for both species. For formamide--water the rotational analysis of ten transitions provides the constants: A = 11 227.931(1) MHz, B = 4586.9628(10) MHz, C = 3258.8278(7) MHz, eQq/sub a//sub a/ = 1.332(3) MHz, and eQq/sub b//sub b/ = 2.037(3) MHz. The formamide--methanol spectrum exhibits an additional splitting from internal rotation of the methyl group. Eighteen observed transitions from the A and E symmetry states have been assigned and fitted with the rotational constants: A = 10 186.594(6) MHz, B = 2090.36(59) MHz, and C = 1762.80(56) MHz with hyperfine constants close to those of formamide--water. By assuming a methyl top moment of inertia I/sub ..cap alpha../ = 3.206 uA/sup 2/, the barrier to internal rotation V/sub 3/ = 231.01(17) cm/sup -1/ is obtained. This barrier height is about 36% smaller than that of methanol. The structures determined for these complexes agree well with prior ab initio calculations which indicate essentially planar, double hydrogen bonded structures for both species.

• Research Organization: Molecular Spectroscopy Division, National Bureau of Standards, Gaithersburg, Maryland 20899
• OSTI ID: 5513434
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 88:2; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ADDUCTS
ALCOHOLS
AMIDES
COMPLEXES
CONFORMATIONAL CHANGES
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FORMAMIDE
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
HYPERFINE STRUCTURE
ISOTOPES
LIGHT NUCLEI
METHANOL
MICROWAVE SPECTRA
NITROGEN 14
NITROGEN ISOTOPES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
QUADRUPOLE MOMENTS
ROTATIONAL STATES
SPECTRA
STABLE ISOTOPES
WATER