Gas-phase oxadisulfane (HSOH), the missing link between the well-known molecules hydrogen peroxide (HOOH) and disulfane (HSSH), was synthesized by flash vacuum pyrolysis of di-tert-butyl sulfoxide. Using mass spectrometry, the pyrolysis conditions have been optimized towards formation of HSOH. Microwave spectroscopic investigation of the pyrolysis products allowed-assisted by high-level quantum-chemical calculations--the first measurement of the rotational-torsional spectrum of HSOH. In total, we have measured approximately 600 lines of the rotational-torsional spectrum in the frequency range from 64 GHz to 1.9 THz and assigned some 470 of these to the rotational-torsional spectrum of HSOH in its ground torsional state. Some 120 out of the 600 lines arise from the isotopomer H(34)SOH. The HSOH molecule displays strong c-type and somewhat weaker b-type transitions, indicating a nonplanar skew chain structure, similar to the analogous molecules HOOH and HSSH. The rotational constants (MHz) of the main isotopomer (A=202 069, B=15 282, C=14 840), determined by applying a least-squares analysis to the presently available data set, are in excellent agreement with those predicted by quantum-chemical calculations (A=202 136, B=15 279, C=14 840). Our theoretical treatment also derived the following barrier heights against internal rotation in HSOH (when in the cis and trans configurations) to be V(cis) approximately equal to 2216 cm(-1) and V(trans) approximately equal to 1579 cm(-1). The internal rotational motion results in detectable torsional splittings that are dependent on the angular momentum quantum numbers J and K(a).

Pure rotational transitions of silicon monosulfide ((28)Si(32)S) and its rare isotopic species have been observed in their ground as well as vibrationally excited states by employing Fourier transform microwave (FTMW) spectroscopy of a supersonic molecular beam at centimetre wavelengths (13-37 GHz) and by using long-path absorption spectroscopy at millimetre and submillimetre wavelengths (127-925 GHz). The latter measurements include 91 transition frequencies for (28)Si(32)S, (28)Si(33)S, (28)Si(34)S, (29)Si(32)S and (30)Si(32)S in upsilon = 0, as well as 5 lines for (28)Si(32)S in upsilon = 1, with rotational quantum numbers J''< or = 52. The centimetre-wave measurements include more than 300 newly recorded lines. Together with previous data they result in almost 600 transitions (J'' = 0 and 1) from all twelve possible isotopic species, including (29)Si(36)S and (30)Si(36)S, which have fractional abundances of about 7 x 10(-6) and 4.5 x 10(-6), respectively. Rotational transitions were observed from upsilon = 0 for the least abundant isotopic species to as high as upsilon = 51 for the main species. Owing to the high spectral resolution of the FTMW spectrometer, hyperfine structure from the nuclear electric quadrupole moment of (33)S was resolved for species containing this isotope, as was much smaller nuclear spin-rotation splitting for isotopic species involving (29)Si. By combining the measurements here with previously published microwave and infrared data in one global fit, an improved set of spectroscopic parameters for SiS has been derived which include several terms describing the breakdown of the Born-Oppenheimer approximation. With this parameter set, highly accurate rotational frequencies for this important astronomical molecule can now be predicted well into the terahertz region.

Advanced renal cell carcinoma (RCC) has a poor prognosis and is characterized by an unpredictable clinical course. The aim of this study was to assess the systemic phospholipid distribution as a possible marker of tumor stage and tumor spread beyond the kidney. To this end, the effect of renal cell carcinoma (RCC) on phospholipid concentrations in blood plasma using 31P NMR spectroscopy was studied in: (a) 29 patients with RCC prior to nephrectomy; (b) 19 healthy volunteers; (c) three patients with other renal tumors (renal metastases of bronchial carcinoma and of renal pelvic carcinoma, and a benign renal tumor). Furthermore, the phospholipid concentrations of eight patients of group (a) were determined 6 months after nephrectomy, when they were in remission. We found considerable deviations in the concentrations of the lysophosphatidylcholines (LPC1, LPC2) in both male and female patients with RCC compared to healthy volunteers (male--LPC1 0.217+/-0.062 vs 0.297+/-0.049 mmol/l, LPC2 0.036+/-0.014 vs 0.068+/-0.024 mmol/l; female--LPC1 0.195+/-0.071 vs 0.296+/-0.044 mmol/l, LPC2 0.037+/-0.027 vs 0.044+/-0.014 mmol/l). In addition, female patients with RCC showed lower concentrations of phosphatidylcholines (PC; 1.409+/-0.268 vs 1.947+/-0.259 mmol/l). The low phospholipid concentrations normalized for patients in remission. Phospholipid concentrations were found to depend on tumor stage and metastatic spread. The deviations in phospholipid concentrations (LPC1, LPC2, PC) observed may be attributable to systemic effects caused by the tumor as well as changes in enzyme activities.

Sulfenic acid (HSOH, 1) has been synthesized in the gas-phase by low-pressure high-temperature (1150 degrees C) pyrolysis of di-tert-butyl sulfoxide (tBu(2)SO, 2) and characterized by means of matrix isolation and gas-phase IR spectroscopy. High-level coupled-cluster (CC) calculations (CCSD(T)/cc-pVTZ and CCSD(T)/cc-pVQZ) support the first identification of the gas-phase IR spectrum of 1 and enable its spectral characterization. Five of the six vibrational fundamentals of matrix-isolated 1 have been assigned, and its rotational-resolved gas-phase IR spectrum provides additional information on the O-H and S-H stretching fundamentals. Investigations of the pyrolysis reaction by mass spectrometry, matrix isolation, and gas-phase FT-IR spectroscopy reveal that, up to 500 degrees C, 2 decomposes selectively into tert-butylsulfenic acid, (tBuSOH, 3), and 2-methylpropene. The formation of the isomeric sulfoxide (tBu(H)SO, 3 a) has been excluded. Transient 3 has been characterized by a comprehensive matrix and gas-phase vibrational IR study guided by the predicted vibrational spectrum calculated at the density functional theory (DFT) level (B3LYP/6-311+G(2d,p)). At higher temperatures, the intramolecular decomposition of 3, monitored by matrix IR spectroscopy, yields short-lived 1 along with 2-methylpropene, but also H(2)O, and most probably sulfur atoms. In addition, HSSOH (6), H(2), and S(2)O are found among the final pyrolysis products observed at 1150 degrees C in the gas phase owing to competing intra- and intermolecular decomposition routes of 3. The decomposition routes of the starting compound 2 and of the primary intermediate 3 are discussed on the basis of experimental results and a computational study performed at the B3LYP/6-311G* and second-order Møller-Plesset (MP2/6-311G* and RI-MP2/QZVPP) levels of theory.

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