Isomers of disulfur dinitride, S2 N2.

UV photolysis (λ=248 or 255 nm) of cyclic S2 N2 isolated in solid argon matrices yields two open-shell S2 N2 isomers, trans SNSN ((3) A'') and cis SNSN ((3) A''), as well as a closed-shell C2v dimer (SN)2 ((1) A1 ). These novel isomers have been characterized by their IR spectra and mutual photo-interconversion reactions. Quantum chemical calculations support the experimental results and also provide insight into the complex potential energy surface of S2 N2 .

Vibrational spectrum and gas-phase structure of disulfur dinitride (S2N2).

Gas-phase FTIR spectra of the ν6 (B-type) and the ν4 (C-type) fundamental bands of S2 N2 (D2h ) were recorded with a resolution of ≤0.004 cm(-1) and the vibrational spectrum of S2 N2 (D2h ) in solid Ar has been revisited. All IR-active fundamentals and four combination bands were assigned in excellent agreement with calculated values from anharmonic VPT2 and VCI theory based on (explicitly correlated) coupled-cluster surfaces. Accurate experimental vibrational ground- and excited-state rotational constants of (32) S2 (14) N2 are obtained from a rovibrational analysis of the ν6 and ν4 fundamental bands, and precise zero-point average rz (Rz (SN)=1.647694(95) Å, αz (NSN)=91.1125(33)°) and semi-experimental equilibrium structures (Re (SN)=1.64182(33) Å, αe (NSN)=91.0716(93)°) of S2 N2 have been established. These are compared to the solid-state structure of S2 N2 and structural properties of related sulfur nitrogen compounds and to results of ab initio structure calculations.

Electronic properties of fluorosulfonyl isocyanate, FSO2NCO: a photoelectron spectroscopy and synchrotron photoionization study.

The electronic properties of fluorosulfonyl isocyanate, FSO2NCO, were investigated by means of photoelectron spectroscopy and synchrotron based techniques. The first ionization potential occurs at 12.3 eV and was attributed to the ejection of electrons formally located at the π NCO molecular orbital (MO), with a contribution from nonbonding orbitals at the oxygen atoms of the SO2 group. The proposed interpretation of the photoelectron spectrum is consistent with related molecules reported previously and also with the prediction of OVGF (outer valence green function) and P3 (partial third order) calculations. The energy of the inner- and core-shell electrons was determined using X-ray absorption, measuring the total ion yield spectra, and the resonances before each ionization threshold were interpreted in terms of transitions to vacant molecular orbitals. The ionic fragmentation mechanisms in the valence energy region were studied using time-of-flight mass spectrometry as a function of the energy of the incident radiation. At 13 eV the M(+) was the only ion detected in the photoion-photoelectron-coincidence spectrum, while the FSO2(+) fragment, formed through the breaking of the S-N single bond, appears as the most intense fragment for energies higher than 15 eV. The photoion-photoion-photoelectron-coincidence spectra, taken at the inner- and core-levels energy regions, revealed several different fragmentation pathways, being the most important ones secondary decay after deferred charge separation mechanisms leading to the formation of the O(+)/S(+) and C(+)/O(+) pairs.

Synthesis, characterization and vibrational properties of p-fluorosulfinylaniline.

The reaction of p-fluoroaniline and SOCl2 rendered p-fluorosulfinylaniline in good yield. The obtained dark yellowish liquid compound was characterized by NMR, UV-visible, FT-IR and Raman spectroscopies. The observed features were consistent with the existence of only one conformer, belonging to the CS symmetry group. A tentative assignment of the vibrational modes was performed on the basis of experimental spectra and quantum chemical calculations at different levels of theory (B3LYP and MP2 with 6-31+G(d), 6-311+G(d) and 6-311+G(df) basis sets). The conformational and vibrational properties of p-fluorosulfinylaniline were in good agreement with experimental data reported for other substituted sulfinylanilines and p-halogenanilines.