Centrifugal distortion in the microwave spectra of cis- and trans-nitrous acids. Determination of the quadratic potential functions and average structures

Abstract

Centrifugal distortion shifts in the microwave spectra of cis and trans nitrous acids and their deuterated species have been analyzed using the first-order treatments of Hill and Edwards, and Watson. The two methods are in close agreement for the ground vibrational state of planar molecules. Centrifugal distortion constants thus derived have been used, together with the infra-red fundamentals and their isotopic shifts, to determine the quadratic potential function for each isomer.Eleven out of a possible sixteen force constants have been determined as follows (in mdyn A-') : for cis nitrous acid, fi ,(OH) = 6.55, fz2(N=O) = 11.18, fss(N-0) = 2.73, f44(NOH) = 0.88, f55(ONO) = 2.46, f 2 3 = 1.80, fZ4 = 0.22, f34 = 0.53, f 3 5 = 0.35, f45 = 0.18 and fs6(torsion) = 0.167; and for trans nitrous acid, f l l = 7.18, f z 2 = 12.28, f 3 3 = 2.22, f44 = 0.76, fS5 = 2.45,

The Case of the Weak N−X Bond: Ab Initio, Semi-Experimental, and Experimental Equilibrium Structures of XNO (X = H, F, Cl, OH) and FNO2

“…Again, an extremely pleasing agreement is found with the structure of Richter, 14 except for the r(O-H) bond length, which seems to be too small by about 0.015 Å. It is interesting that the corrections r z -r e used by Finnigan et al 6 are different from the values deduced from the cubic force field. Finnigan et al 6 assumed that a good portion of the cubic force constants comes from the nonlinear transformation of the quadratic constants.…”

“…It is interesting that the corrections r z -r e used by Finnigan et al 6 are different from the values deduced from the cubic force field. Finnigan et al 6 assumed that a good portion of the cubic force constants comes from the nonlinear transformation of the quadratic constants. …”

“…7 They also attempted to determine r e BO of HONO using a rather crude model cubic force field. 6 As it turns out, this last structure is rather inaccurate. Furthermore, the r z (OH) bond length at 0.947 Å seems to be too short, as shown below and in Table 1.…”

“…The {ν 5 , ν 3 , ν 6 , ν 2 } Coriolis interacting tetrad of FNO 2 has been analyzed carefully taking into account all interactions. 71 a The claimed uncertainties correspond to standard deviations of the fit and do not correctly reflect inherent modeling errors, which are expected to be much larger.…”

Molecular g-Values, Magnetic Susceptibility Anisotropies, Molecular Quadrupole Moments and the Anisotropies in the Electronic Charge Distribution in HNO2-Cis, DNO2-Cis, HNO2-Trans, and DNO2-Trans

“…The rotational spectrum of nitrous acid has been first investigated by Cox and Kuczkowski in 1966 [4] and has subsequently been extensively studied by Cox and coworkers [5,6], The molecule was found to exist in two planar configurations (see …”