: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

The flip side of the robust stability of N2 is the instability of any larger molecules composed exclusively of nitrogen. These molecules nonetheless remain enticing targets for explosive and propellant applications. Zhang et al. successfully prepared the pentazolate ion, a negatively charged ring of five nitrogens, by oxidative cleavage of a C–N bond in an aryl-substituted precursor (see the Perspective by Christe). The molecule was stabilized and isolated in the solid state as a hydrated ammonium chloride salt. Spectroscopic and crystallographic characterization confirmed the ring's planar geometry.

Science , this issue p. [374][1]; see also p. [351][2]

 [1]: /lookup/doi/10.1126/science.aah3840
 [2]: /lookup/doi/10.1126/science.aal5057

http://science.sciencemag.org/content/sci/355/6323/374.full.pdf

Synthesis and characterization of the pentazolate anion cyclo-N5ˉ in (N5)6(H3O)3(NH4)4Cl

Ozone is a unique species whose chemistry has a profound impact in many areas of our society. It is well known as a beneficial constituent of the upper atmosphere which shields living organisms fro...

Chemical and Catalytic Properties of Ozone

Recently we reported that antibodies can generate hydrogen peroxide (H_2O_2) from singlet molecular oxygen (^1O_2^*). We now show that this process is catalytic, and we identify the electron source for a quasi-unlimited generation of H_2O_2. Antibodies produce up to 500 mole equivalents of H_2O_2 from^1O_2^*, without a reduction in rate, and we have excluded metals or Cl– as the electron source. On the basis of isotope incorporation experiments and kinetic data, we propose that antibodies use H_2O as an electron source, facilitating its addition to ^1O_2^* to form H_2O_3 as the first intermediate in a reaction cascade that eventually leads to H_2O_2. X-ray crystallographic studies with xenon point to putative conserved oxygen binding sites within the antibody fold where this chemistry could be initiated. Our findings suggest a protective function of immunoglobulins against ^1O_2^* and raise the question of whether the need to detoxify ^1O_2^* has played a decisive role in the evolution of the immunoglobulin fold.

https://science.sciencemag.org/content/sci/293/5536/1806.full.pdf

Antibody catalysis of the oxidation of water

The coupling of two or more molecules of dinitrogen (N2) occurs naturally under the radiative conditions present in the ionosphere and may be achieved synthetically under ultrahigh pressure or plasma conditions. However, the comparatively low N-N single-bond enthalpy generally renders the catenation of the strongly triple-bonded N2 diatomic unfavorable and the decomposition of nitrogen chains a common reaction motif. Here, we report the surprising organoboron-mediated catenation of two N2 molecules under near-ambient conditions to form a complex in which a [N4]2- chain bridges two boron centers. The reaction entails reductive coupling of two hypovalent-boron-bound N2 units in a single step. Both this complex and a derivative protonated at both ends of the chain were characterized crystallographically.

The reductive coupling of dinitrogen.

Tetranitrogen (N 4 ), which has been the subject of great theoretical interest, has been prepared from the N 4 + cation and positively detected as a gaseous metastable molecule with a lifetime exceeding 1 microsecond in experiments based on neutralization-reionization mass spectrometry. An examination of the geometry of N 4 + and the fragmentation pattern of the 14 N 2 15 N 2 neutral molecule has revealed that the latter is characterized by an open-chain geometry with two distinct, closely bound N 2 units joined by a longer weaker bond.

https://science.sciencemag.org/content/sci/295/5554/480.full.pdf

Experimental Detection of Tetranitrogen

Hydrogen trioxide (HO3) has long been postulated as a key intermediate in important atmospheric processes but has proved difficult to detect. The molecule was unequivocally detected in experiments based on neutralization-reionization and neutralization-reionization/collisionally activated dissociation mass spectrometry, using protonated ozone (HO3+) as the charged precursor. Hydrogen trioxide is a relatively stable species and has a H-O-O-O connectivity and a lifetime exceeding 10–6 seconds at ambient temperature.

/pdf/experimental-detection-of-hydrogen-trioxide-2j5x1za0eh.pdf

Experimental Detection of Hydrogen Trioxide

Although suggested by Lewis in 1924 and theoretically predicted, O4 has so far proved extremely elusive, defying all attempts at the positive experimental detection of a bound, intact O4 species. The search has now been brought to an end by the conclusive proof, achieved by neutralization-re-ionization mass spectrometry, of the existence of intact O4 as a gas-phase species with a lifetime in excess of 1 μs, whose dissociation requires overcoming a barrier of the order of 10 kcal mol-1 .

Experimental Detection of Tetraoxygen

The Proton Affinity and Gas-Phase Basicity of Sulfur Dioxide

The impervious route to the elusive HOOO− anion

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