The N-alkyl-C-polyfluoroalkyl-C-chlorosulfinimides RFC(Cl)SN R have been investigated. Some aspects of their thermal stability and their [3 + 2] and [3 + 1] cycloaddition reactions have been examined. 相似文献
The existence of the orbital interaction presented in the literature as being the cause for the stabilisation of the Z,Z configuration of Ph-S-N=S=N-S-Ph (1) and its derivatives in the crystal phase, has been investigated. The results of theoretical calculations at the DFT/B3LYP/6-311+G* level of theory suggest that such a stabilising interaction might not exist or be extremely weak and that packing forces must be the main cause of the observed Z,Z configuration in the solid. To reach this conclusion structural and energetic parameters were combined to study the bonding in these -S-N=S=N-S- systems. For the analogous Ph-Se-N=S=N-Se-Ph (2) in particular the isomeric equilibrium in solution found in the variable-temperature 77Se NMR spectrum indicates that, in the gas phase or in solution, the observed Z,Z configuration is not stabilised to a greater extent than the Z,E configuration. 相似文献
M4X3[Si2O7]-Type Lanthanide Chalcogenide Disilicates (M ? Ce? Er; X ? S, Se) Attempts to produce single crystals of MSe2 (or MSe2?X) by vapour phase transport with iodine or the oxidation of MCl2 (or MClH) with sulfur in the presence of NaCl in sealed evacuated quartz containers often yielded well-grown single crystals with the composition M4X3[Si2O7] (M ? pr, Sm, Gd, X ? Se, and M ? Nd, Er, X ? S) as by-products. The crystal structures (tetragonal, 141/amd (no. 141)), Z = 8, contain two crystallographically independent M3+ Cations that are interconnected by chalcogenide (X2?) and disilicate anions ([Si2O7]6?). (M1)3+ is surrounded by eight (five X2? and three terminal O2? of the disilicate group), (M2)3+ by nine (three X2? and six terminal O2? of the [Si2O7]6? anion) chalcogenide anions. The disilicate anion itself exhibits the eclipsed conformation with non-linear Si? O? Si bridges (angles: 128 – 133°). 相似文献
A dimer of thioxo-N-t-butylimino(trimethylsiloxy)-phosphorane 5 has been prepared by reaction of tris(trimethylsilyl) phosphine with N-sulfinyl-N-tert-butylamine. The structure of 5 has been confimed by X-ray analysis data. 1-Aza-2-thia-3-phosphaallene 1 , thiaphosphaziridine 3 , iminophosphine P-sulfide 4 are postulated as intermediates of the reaction studied. 相似文献
Trimethylsilyltrifluoromethane sulfonate is shown to be an efficient catalyst for the elimination of Me3SiCl from N-trimethylsilyl-N-(2,4,6-tri-tert-butylphenyl)amidochlorophosphites la-f , leading to the phosphenimidous esters 3a–f. The crystal structures of phosphites 1a and 1d provide a stereochemical explanation for the better thermal stability of 1d On the basis of these observations a convenient and general synthesis of phosphenimidous esters 3a–f is presented. 相似文献
Sensitized photolysis : We describe a series of macrocyclic disulfides containing stiff stilbene (see scheme) as the intramolecular photosensitizer designed for fundamental mechanistic studies of sensitized photolysis of the S? S bond. Preliminary studies revealed weak temperature dependence of the quantum yields, which decreased exponentially with Boltzmann‐weighted average separation between the S? S bond and stiff stilbene.
The reactivity of disulfide and diselenide derivatives towards F? and CN? nucleophiles has been investigated by means of B3PW91/6‐311+G(2df,p) calculations. This theoretical survey shows that these processes, in contrast with the generally accepted view of disulfide and diselenide linkages, do not always lead to S? S or Se? Se bond cleavage. In fact, S? S or Se? Se bond fission is the most favorable process only when the substituents attached to the S or the Se atoms are not very electronegative. Highly electronegative substituents (X) strongly favor S? X bond fission. This significant difference in the observed reactivity patterns is directly related to the change in the nature of the LUMO orbital of the disulfide or diselenide derivative as the electronegativity of the substituents increases. For weakly electronegative substituents, the LUMO is a σ‐type S? S (or Se? Se) antibonding orbital, but as the electronegativity of the substituents increases the π‐type S? X antibonding orbital stabilizes and becomes the LUMO. The observed reactivity also changes with the nature of the nucleophile and with the S or Se atom that undergoes the nucleophilic attack in asymmetric disulfides and diselenides. The activation strain model provides interesting insights into these processes. There are significant similarities between the reactivity of disulfides and diselenides, although some dissimilarities are also observed, usually related to the different interaction energies between the fragments produced in the fragmentation process. 相似文献
The ability of bridging thiophenolate groups (RS?) to transmit magnetic exchange interactions between paramagnetic NiII ions is examined. Specific attention is paid to complexes with large Ni? SR? Ni angles. For this purpose, dinuclear [Ni2L1(μ‐OAc)?I2][I5] ( 2 ) and trinuclear [Ni3L2(OAc)2][BPh4]2 ( 3 ), where H2L1 and H2L2 represent 24‐membered macrocyclic amino‐thiophenol ligands, are prepared and fully characterized by IR‐ and UV/Vis spectroscopy, X‐ray crystallography, static magnetization M measurements and high‐field electron spin resonance (HF‐ESR). The dinuclear complex 2 has a central N3Ni2(μ‐S)2(μ‐OAc)Ni2N3 core with a mean Ni? S? Ni angle of 92°. The macrocycle L2 supports a trinuclear complex 3 , with distorted octahedral N2O2S2 and N2O3S coordination environments for one central and two terminal NiII ions, respectively. The Ni? S? Ni angles are at 132.8° and 133.5°. We find that the variation of the bond angles has a very strong impact on the magnetic properties of the Ni complexes. In the case of the Ni2‐complex, temperature T and magnetic field B dependencies of M reveal a ferromagnetic coupling J=?29 cm?1 between two NiII ions (H=JS1S2). HF‐ESR measurements yield a negative axial magnetic anisotropy (D<0) which implies a bistable (easy axis) magnetic ground state. In contrast, for the Ni3‐complex we find an appreciable antiferromagnetic coupling J′=97 cm?1 between the NiII ions and a positive axial magnetic anisotropy (D>0) which implies an easy plane situation.相似文献
Room temperature reactions of S4N4 with (amino) diphenylphosphines, (R)Ph2P, have basically yielded two different types of S N heterocycles under two different stoichiometric conditions. Phosphiniminocyclotrithiatriazenes, (R)Ph2PN S3N3 (R = C4H8N , C5H10N , C6H12N , CH3NC4H8N , (C6H11)2 N , and (C6H5CH2)2N ) have been obtained (yield 45–76%) from a 1:2 mole ratio (S4N4:(R)Ph2P) reaction, while the disubstituted S4N4 derivatives, 1,5-[Ph2(R)PN]2S4N4 (R = C4N8N , C5H10N , and C6H12N ) have been obtained (yield 30–45%) only from a 1:3.5–4 mole ratio reaction. All the 1,5-[Ph2(R)PN]2S4N4 derivatives prepared in this study undergo a room temperature solution phase transformation to the corresponding (R)Ph2PN S3N3 heterocycles. 相似文献
Catalytic insertion or addition of a metal‐imido/nitrene species, generated from reaction of a transition‐metal catalyst with iminoiodanes, to C? H and C?C bonds offers a convenient and atom economical method for the synthesis of nitrogen‐containing compounds. Following this groundbreaking discovery during the second half of the last century, the field has received an immense amount of attention with a myriad of impressive metal‐mediated methods for the synthesis of amines and aziridines having been developed. This review will cover the significant progress made in improving the efficiency, versatility and stereocontrol of this important reaction. This will include the various iminoiodanes, their in situ formation, and metal catalysts that could be employed and new ligands, both chiral and non‐chiral, which have been designed, as well as the application of this functional group transformation to natural product synthesis and the preparation of bioactive compounds of current therapeutic interest. DOI 10.1002/tcr.201100018 相似文献
A new unsymmetrical geminal dianion that contained both a phosphine oxide moiety and a phosphine sulfide moiety has been synthesized. Its reactivity towards RuII was explored, which led to the formation of a highly reactive carbene complex that evolved at room temperature to yield a kinetic orthometalated RuII complex through C? H activation of the phenyl group of the phosphine oxide moiety. This insertion was found to be thermally reversible and a second C? H insertion occurred at a phenyl group of the phosphine sulfide moiety to form the thermodynamic orthometalated RuII complex in a diastereospecific manner. DFT calculations fully rationalized the experimental findings in terms of the relative energies of the kinetic and thermodynamic products and allowed the mechanism of this process to be fully understood. 相似文献
A mononuclear nonheme cobalt(III) complex of a tetradentate ligand containing two deprotonated amide moieties, [Co(bpc)Cl2][Et4N] ( 1 ; H2bpc=4,5‐dichloro‐1,2‐bis(2‐pyridine‐2‐carboxamido)benzene), was prepared and then characterized by elemental analysis, IR, UV/Vis, and EPR spectroscopy, and X‐ray crystallography. This nonheme CoIII complex catalyzes olefin epoxidation upon treatment with meta‐chloroperbenzoic acid. It is proposed that complex 1 shows partitioning between the heterolytic and homolytic cleavage of an O? O bond to afford CoV?O ( 3 ) and CoIV?O ( 4 ) intermediates, proposed to be responsible for the stereospecific olefin epoxidation and radical‐type oxidations, respectively. Moreover, under extreme conditions, in which the concentration of an active substrate is very high, the Co? OOC(O)R ( 2 ) species is a possible reactive species for epoxidation. Furthermore, partitioning between heterolysis and homolysis of the O? O bond of the intermediate 2 might be very sensitive to the nature of the solvent, and the O? O bond of the Co? OOC(O)R species might proceed predominantly by heterolytic cleavage, even in the presence of small amounts of protic solvent, to produce a discrete CoV?O intermediate as the dominant reactive species. Evidence for these multiple active oxidants was derived from product analysis, the use of peroxyphenylacetic acid as the peracid, and EPR measurements. The results suggest that a less accessible CoV?O moiety can form in a system in which the supporting chelate ligand comprises a mixture of neutral and anionic nitrogen donors. 相似文献