Cyclic and Heterocyclic Thiazenes

Structures and EPR spectra of binary sulfur−nitrogen radicals from DFT calculations

Sulfur and nitrogen represent one of the most studied inorganic binary systems at ambient pressure on account of their large wealth of metastable exotic ring-like compounds. Under high pressure con...

High Pressure Investigation of the S–N2 System up to the Megabar Range: Synthesis and Characterization of the SN2 Solid

Molybdenum and tungsten chlorides, chloride oxides and chloride nitrides as well as thiazene and phosphazene metallacycles were studied by electrochemical methods in CH2Cl2. The different ligand systems have a profound influence on the redox potentials. The stabilization of high valency increases from the hexachloro to pentachlorooxo to chloronitrido complexes and the metallacycles. There is a systematic difference in the electrode potentials between molybdenum and tungsten redox couples. The geometries of the d1 and d0 species, optimized using density functional methods, are in good agreement with the available experimental data and trends in redox data are reproduced by the computed energy difference between the appropriate d1/d0 pair. The relative stability of the higher oxidation state is directly linked to the donor properties of the ligands present, and increases in the order: Cl6 < F6 < Cl5O < Cl4(N3S2) < Cl3(N3P2) < Cl4N.

Stabilization of high oxidation states in transition metals. An electrochemical and computational study of structurally comparable molybdenum and tungsten complexes

NSERC ; U.S.A. by NSF [CHE-0716718]; Institute for Functional Nanomaterials [0701525]; U.S. Environmental Protection Agency [RD-83385601]; NSFC [20973137, 20721002, 20423002]; 973 program [2007CB815307]

Synthesis, properties, and bishomoaromaticity of the first tetrahalogenated derivative of a 1, 5-diphosphadithiatetrazocine: a combined experimental and computational investigation.

The oxidative addition of Cl2 (using SO2Cl2) to the six-membered ring (R2PN)(SN)2 (R = Me, Ph) produces the mixed phosphazene–thiazyl heterocycles, (R2PN)(NSCl)2, which react with Me3SiNSNSiMe3 to give the bicyclic compounds R2PS3N5. The latter undergo thermal decomposition, at ca. 100 °C in toluene, via reductive elimination of an NSN unit to regenerate (R2PN)(SN)2 in high yield. Kinetic measurements of this process, using 31P nmr spectroscopy, yield an activation energy of 102.4 ± 6.0 kJ mol−1 for the release of the NSN fragment from Me2PS3N5. The thermolysis route has been used to prepare the thermally unstable (F2PN)(SN)2, characterized as a 1:1 adduct with norbornadiene.

Tom Oswald

Papers

Synthetic and kinetic studies of the reversible addition of a bridging NSN fragment to the electron-rich heterocycles (R2PN)(SN)2 (R = Me, Ph, F)