Identification of -BH with Three Bridging B-H-B Bonds in a Six-Membered Ring.

Irradiation of samples of diborane(6), BH and BD, separately and together, dispersed in solid neon near 4 K with tunable far-ultraviolet light from a synchrotron yielded new infrared absorption lines that are assigned to several carriers. Besides H, B, BH, BH, BH, B, BH, and BH, previously identified, a further species is assigned on the basis of quantum-chemical calculations of vibrational wavenumbers and intensities to be -BH ( , singlet state) in several isotopic variants, which feature three bridging B-H-B bonds in a six-membered ring.

The vibrational g-factor of dihydrogen from theoretical calculation and analysis of vibration-rotational spectra.

We present the first results from quantum-chemical calculation of a vibrational g-factor; the calculations were performed at the level of full configuration interaction using a basis set of aug-cc-pVQZ quality. The theoretical results are consistent with experimental results from analysis of pure rotational and vibration-rotational spectra of dihydrogen in six isotopic variants, in which calculated results for either the rotational g-factor or adiabatic corrections are employed to constrain fits of coefficients of radial functions from wave numbers of transitions. When fits are constrained with data for the rotational g-factor, we reproduce also the radial dependence of adiabatic corrections relative to their value at equilibrium internuclear separation.