Interatomic Distances and Nuclear Quadrupole Couplings in ClCN, BrCN, and ICN

Abstract

The following nuclear and molecular constants have been obtained from microwave measurements of the pure rotational spectra of C1CN (7=2-3 transition), BrCN (7=3-4), and ICN (7 = 4-5). The moments of inertia from the ground vibrational states are, in g-cm 2 .0T2. The interatomic distances in A for the ground vibrational states are dca-1.630, dew-1.163, for C1CN; dcBr = 1.789, dew = 1.160, for BrCN; and <fci = 1.995, ffc N = 1.159, for ICN. Quadrupole couplings in mc/s evaluated from the hyperfine structure are: for CI 35 , -83.5; for C\ m , -65.0; for Br 79 , 686; for Br 81 , 573; and for I 127 , -2420.

Millimeter-wave spectrum of BrCN produced by dc discharge

“…The analysis of the rotational spectrum of cyanogen bromine and several of its isotopic species for some low J (J ¼ 2, 3) transitions have been reported by previous workers [7,10]. Hence, preliminary values of B o and eQq of Br for the ground vibrational state are known.…”

“…The quadrupole structure due to 14 N nucleus was not resolved. The observed transition frequencies were analyzed using the following expression for the frequency of rotational transition of a linear polyatomic molecule with a single quadrupole nucleus [17]: Tables 3 and 4 along with parameters determined in [10,12,13]. The observed frequencies have been corrected to second order quadrupole terms for the determination of the quadrupole coupling constant eQq.…”

“…Later on, the J ¼ 3 ! 4 rotational transitions of BrCN have been observed and analyzed by Gordy et al [9,10]. The rotational analysis has been extended to the millimeter-wave region by Burrus et al [11] and to the millimeter-wave and submillimeter-wave region by Le Guennec et al [12] who have reported only the quadrupole free line centers.…”

The Crystal Structure of Cyanogen Chloride

“…If the molecules were bent and disordered or rotating, we would expect the atoms to appear (Booth, 1948), shows that r6b~ Iac this distortion is merely a result of series termination (cf. Fractional electronic point charges were located on the iodine end nitrogen atoms in the crystal, with the I...N distance calculated from the length of the molecule in the vapor (Smith et al, 1948 One further feature of the structure determination which deserves some comment is the peak in the electron density at…”