Articles you may be interested inDistortion of ethyne on coordination to silver acetylide, C2H2AgCCH, characterised by broadband rotational spectroscopy and ab initio calculations Distortion of ethyne on formation of a π complex with silver chloride: C2H2Ag-Cl characterised by rotational spectroscopy and ab initio calculations Millimeter-wave spectroscopy and coupled cluster calculations for a new phosphorus-carbon chain: HC 5 P Silene, H 2 CSiH 2 , has been efficiently produced by pyrolysis of 5,6-bis͑trifluoromethyl͒-2-silabicyclo͓2.2.2͔octa-5,7-diene ͑SBO͒. Seven isotopomers have been observed by millimeterand submillimeter-wave spectroscopy. From the different sets of experimental molecular parameters and from ab initio calculations of the rovibrational interaction parameters, the equilibrium structure has been obtained by a least squares analysis of the rotational constants. The results are: r e (SivC) ϭ 1.7039(18) Å, r e (C-H) ϭ 1.0819(12) Å, r e (Si-H) ϭ 1.4671(9) Å, ЄHCSi ϭ 122.00(4)°, and ЄHSiC ϭ 122.39(3)°. This experimental structure is in excellent agreement with the equilibrium geometry calculated at the CCSD͑T͒ level of theory with a cc-pV͑Q,T͒Z basis set. This is the first experimental determination without any constraint of the SivC double bond length in the parent compound of the silaalkene family. A lifetime of 30 ms has been observed for this molecule in the gas phase at low pressure.

An alkyne–vinylidene isomerization is also possible with the difluoro compounds 1 and 2! Irradiation of 2 (λ = 193 nm) in an Ar matrix yields 1 exclusively. The IR spectrum agrees with results of novel abinitio calculations, which also suggest that 1—in sharp contrast to the vinylidenes RHCC—is protected against isomerization into 2 by a kinetic barrier. Irradiation with light with λ > 230nm converts 1 back into 2. Already at 35–42 K 1 adds CO and N2 to yields F2CCCO and F2CCNN, respectively.

Difluorovinylidene is a highly reactive and extremely electrophilic singlet carbene that thermally abstracts an oxygen atom from CO 2 at temperatures as low as 30 K. The resulting difluoroketene is characterized for the first time using IR spectroscopy in combination with isotopic labeling and density functional theory (DFT) calculations. The three observed IR absorptions of the ketene at 1274, 1427, and 2162 cm À1 are assigned to the asymmetrical FCF stretching vibration and the asymmetrical and symmetrical CCO stretching vibrations, respectively. The oxidation of difluorovinylidene with 3 O 2 results in a complex product mixture with CF 2 , C 2 F 4 , CO 2 , COF 2 , and CO as the major products. A mechanism consistent with all observed products is proposed.

CO2 laser‐induced infrared multiphoton decomposition (IRMPD) and SF6 photosensitized decomposition (LPD) of silacyclobutane (SCB) and 1,3‐disilacyclobutane (DSCB) in the gas phase results in the very efficient deposition of Si/C/H and SiC materials, and it is inferred that the process is dominated by formation of transient silene; silene rearrangement to methylsilylene; silene and methylsilylene dehydrogenation; and polymerization of SiCHn (n < 4) species. The deposits are sensitive to oxygen. Decomposition and SiC formation are favoured with IRMPD experiments conducted with high‐energy fluxes. The laser technique is promising for low‐temperature chemical vapour deposition of amorphous SiC.

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