Photochemical Reaction Channels of OCS with Cl2, ICl, or IBr Isolated Together in an Argon Matrix: Isolation of syn-Iodocarbonylsulfenyl Bromide

Preparation of FC(S)SF, FC(S)SeF and FC(Se)SeF through matrix photochemical reactions of F2 with CS2, SCSe, and CSe2

The reactions of F₂ with CS₂, SCSe, and CSe₂, respectively, were analyzed under matrix conditions by co-deposition of the halogen with the triatomic molecules trapped in argon matrices at cryogenic temperatures. In all cases, after co-deposition, the formation of the respective van der Waals complexes is observed. When each mixture is subsequently irradiated by means of broad-band UV-visible light (200 ≤ λ ≤ 800 nm), FC(S)SF, fluorothiocarbonylsulfenyl fluoride, FC(S)SeF, fluorothiocarbonylselenyl fluoride and FC(Se)SeF, fluoroselenocarbonylselenyl fluoride are produced, respectively. All these species exist as two stable planar syn- and anti-conformers (syn- and anti- of the CZ double bond, Y = S, Se, with respect to the S-F or Se-F single bond, respectively). For FC(S)SF, syn- is the rotamer with the lowest energy, while for both FC(S)SeF and FC(Se)SeF the anti-form is the lowest energy conformer. In all cases, other products due to alternative or subsequent photochannels are observed during the photochemical processes carried out in argon matrices at cryogenic temperatures.

Reactivity of Binary and Ternary Sulfur Halides towards Transition-Metal Compounds

Binary sulfur fluorides exhibit an interesting reactivity towards transition metal complexes. They open up routes for the generation of sulfur‐containing building blocks. Often ligands with particular properties can be constructed. This includes their ability to transfer sulfur atoms or polysulfide units as well as fluorination reactions. This Minireview provides an insight into the reactivity of the binary and ternary sulfur halides S₂Cl₂, SCl₂, SF₄, SF₆ and SF₅Cl towards transition‐metal compounds.

Chloro- and Dichloro-methylsulfonyl Nitrenes: Spectroscopic Characterization, Photoisomerization, and Thermal Decomposition

Chloro- and dichloro-methylsulfonyl nitrenes, CH₂ClS(O)₂N and CHCl₂S(O)₂N, have been generated from UV laser photolysis (193 and 266 nm) of the corresponding sulfonyl azides CH₂ClS(O)₂N₃ and CHCl₂S(O)₂N₃, respectively. Both nitrenes have been characterized with matrix-isolation IR and EPR spectroscopy in solid N₂ (10 K) and glassy toluene (5 K) matrices. Triplet ground-state multiplicity of CH₂ClS(O)₂N (|D/hc| = 1.57 cm^-1 and |E/hc| = 0.0026 cm^-1) and CHCl₂S(O)₂N (|D/hc| = 1.56 cm^-1 and |E/hc| = 0.0042 cm^-1) has been confirmed. In addition, dichloromethylnitrene CHCl₂N (|D/hc| = 1.57 cm^-1 and |E/hc| = 0 cm^-1), formed from SO₂-elimination in CHCl₂S(O)₂N, has also been identified for the first time. Upon UV light irradiation (365 nm), the two sulfonyl nitrenes R⁻S(O)₂N (R = CH₂Cl and CHCl₂) undergo concomitant 1,2-R shift to N-sulfonlyamines R⁻NSO₂ and 1,2-oxygen shift to S-nitroso compounds R⁻S(O)NO, respectively. The identification of these new species with IR spectroscopy is supported by ¹⁵N labeling experiments and quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) level. In contrast, the thermally-generated sulfonyl nitrenes CH₂ClS(O)₂N (600 K) and CHCl₂S(O)₂N (700 K) dissociate completely in the gas phase, and in both cases, HCN, SO₂, HCl, HNSO, and CO form. Additionally, ClCN, OCCl₂, HNSO₂, •NSO₂, and the atmospherically relevant radical •CHCl₂ are also identified among the fragmentation products of CHCl₂S(O)₂N. The underlying mechanisms for the rearrangement and decomposition of CH₂ClS(O)₂N and CHCl₂S(O)₂N are discussed based on the experimentally-observed products and the calculated potential energy profile.

Matrix isolation of the elusive fluorocarbonylsulfenyl fluoride molecule FC(O)SF

The syn and anti conformers of the hitherto unknown fluorocarbonylsulphenyl fluoride FC(O)SF were formed through the photochemical reactions between OCS and F(2), isolated in solid Ar. The reactions were followed by Fourier transform infrared (FTIR) spectroscopy, and the unknown products were proposed by comparison of the observed IR absorptions with their computed IR spectra. The reactions occur through a 1:1 molecular complex between OCS and F(2), forming the anti-FC(O)SF first, which subsequently transforms into the syn form, through a randomization process. At longer times of irradiation, FC(O)SF decomposes by extrusion of a CO molecule with the concomitant formation of SF(2) and the formation of a difluorophosgene molecule, O═CF(2). The migration of fluorine atoms in the matrixes is proposed to explain the formation of SF(4) and SF(6).

The Bromide - Carbon Monoxide Gas Phase Complex: Anion Photoelectron Spectroscopy and Ab Initio Calculations

The anion photoelectron spectrum of the bromide–carbon monoxide complex is presented in combination with supporting ab initio calculations. The spectrum features transitions between anion and neutral van der Waals complexes, Br⋯CO. A stabilization energy of 0.14 ± 0.05 eV is extracted from the spectrum, while the predicted binding energy for the anion complex is 9.9 kJ mol–1 from CCSD(T)/aug-cc-pVTZ calculations. The electron affinity of the Br⋯CO complex is 3.50 ± 0.05 eV. The ab initio calculations reveal a previously unreported minimum for the neutral radical complex, namely the van der Waals Br⋯OC linear complex.

Early Barriers in the Matrix Photochemical Formation ofsyn–anti Randomized FC(O)SeF from the OCSe:F2 Complex

The photochemically induced reaction of OCSe and F(2), isolated together in an Ar matrix at about 15 K, leads to formation of the hitherto-unknown fluorocarbonylselenyl fluoride FC(O)SeF. The reaction occurs via a van der Waals complex O=C=Se...F-F that favors very early formation of the anti conformer. The presence and subsequent decay of a band assigned to the F-F vibration correlated with perturbed OCSe bands seems to confirm this hypothesis. Subsequent irradiation of the matrix leads to randomized FC(O)SeF by a photochemically induced conformational equilibrium between syn and anti forms. Another photochemical reaction channel is the formation of CO and SeF(2) molecules, which are produced in the same matrix cage and then form a loose complex. The changes were monitored and the products characterized experimentally by their IR spectra, and the spectra analyzed in the light of the results of theoretical calculations.

Methanesulfenyl Fluoride, CH3SF, a Missing Link in the Family of Sulfenyl Halides: Formation and Characterization through the Matrix Photochemistry of Methyl Thiofluoroformate, FC(O)SCH3

Matrix-isolation experiments have afforded the means of preparing the hitherto unknown sulfur(II) fluoride, methanesulfenyl fluoride, CH3SF. Broadband UV-visible irradiation of methyl thiofluoroformate, FC(O)SCH3, isolated in a solid Ar matrix results, first, in photoisomerization of the syn into the anti form of the molecule, and, subsequently, in the elimination of CO with the concomitant formation of CH3SF. Continued irradiation brings about tautomerization of this product with the detachment and migration of a hydrogen from the methyl group to give the molecular complex H2C==S...HF. The changes have been monitored and the photoproducts detected and identified by the IR spectra of the matrices, and the conclusions confirmed: 1) with reference to the corresponding behavior of the perdeuterated molecule FC(O)SCD3; 2) by analogy with the properties of related molecules, for example, ClC(O)SCH3, CH3SCl, and H2C==S...HCl, and; 3) by comparison with the vibrational properties simulated for the different molecules by ab initio and density functional theory methods.

Formation of New Halogenothiocarbonylsulfenyl Halides, XC(S)SY, through Photochemical Matrix Reactions Starting from CS2and a Dihalogen Molecule XY (XY = Cl2, Br2, or BrCl)

Isolation of a dihalogen molecule XY (XY=Cl2, Br2, or BrCl) with CS2 in a solid Ar matrix at about 15 K leads, by broad-band UV-vis photolysis (200<or=lambda<or=800 nm), to a variety of products depending on the natures of X and Y. These products have been identified on the basis of the IR spectra of the matrices. In addition to the familiar species SCCl2, ClCS*, Cl*...SCS, CCl4, *CCl3, :CCl2, SCl2, SCBr2, CBr4, *CBr3, BrC(S)Cl, BrCCl3, and :CBrCl, the following new molecules have also been identified as products of the various photoreactions: syn-ClC(S)SCl, anti-ClC(S)SCl, syn-BrC(S)SBr, anti-BrC(S)SBr, syn-ClC(S)SBr, anti-ClC(S)SBr, syn-BrC(S)SCl, anti-BrC(S)SCl, ClC(S)S*, BrCS*, and Br*...SCS. The IR spectra of these hitherto unknown species have been interpreted with reference to the predictions of ab initio (HF and MP2) and density functional theory (DFT) calculations. The results are analyzed in relation to the reaction pathways accessed by matrix photolysis.

Matrix-Isolated van der Waals Complexes Formed between CS2 and Dihalogen Molecules XY, Where XY = Cl2, Br2, BrCl, ICl, or IBr

Weakly bound 1:1 complexes formed between CS2 and a dihalogen molecule XY = Cl2, Br2, BrCl, ICl, or IBr have each been trapped in an Ar matrix and hence investigated experimentally by their IR spectra as well as theoretically by MP2 and density functional calculations. A planar structure, with an intermolecular angle close to 90 degrees , is expected for such a S=C=S...XY molecular complex. Moreover, for each system involving a heteronuclear dihalogen, two possible complexes exist, viz., S=C=S...XY and S=C=S...YX. The calculated structures, vibrational properties, and binding energetics of the complexes are analyzed, and the NBO formalism is used to interpret their bonding properties. The IR spectra of the complexes thus simulated provided vital guidance for the interpretation of the matrix spectra. For example, complexation was predicted and observed (i) to induce red shifts of the principal absorptions associated with both the CS2 and XY components and (ii) to result, through the change in symmetry, in activation of some modes that are IR-silent for the free components.