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Issue 11, 1990
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Dicyanomethane : microwave spectrum, quadrupole coupling and structure

Abstract

The microwave spectra of seven isotopic species of CH2(CN)2 have been studied in the ground vibrational state. The zero-point average structure has been determined to be: r(C—C)= 1.459(2)Å, r(C[triple bond, length as m-dash]N)= 1.160(2)Å and r(C—H)= 1.109(2)Å with ∠ CCN = 180 – 1.4(3)°, ∠ CCC/2 = 56.3(2)° and ∠ HCH/2 = 53.5(2)°. A near-equilibrium structure has also been estimated using an rρm method tested by a similar calculation for formaldehyde. Microwave Fourier-transform spectroscopy has been used to investigate the main species and single-nitrogen-15 species under high resolution. For CH2(CN)C15N accurate 14N quadrupole coupling constants have been determined as χaa=–2.364(9) MHz, χbb= 0.313(6) MHz and χcc= 2.051(6) MHz. These results have been combined with those previously obtained for the main species to show that the quadrupole tensor is almost symmetrical about the C[triple bond, length as m-dash]N bond direction. There is some disagreement between the constants for the two isotopic molecules close to experimental error, possibly indicating zero-point vibrational effects on the coupling tensor. The quadrupole tensor is of especial interest in CH2(CN)2 in view of the bent CCN moieties.

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Article type: Paper
DOI: 10.1039/FT9908601981
J. Chem. Soc., Faraday Trans., 1990,86, 1981-1989

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    Dicyanomethane : microwave spectrum, quadrupole coupling and structure

    J. Randell, A. P. Cox, I. Merke and H. Dreizler, J. Chem. Soc., Faraday Trans., 1990, 86, 1981
    DOI: 10.1039/FT9908601981

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