Synthesis of a novel tricyclic 1,4-diphosphinine I and, subsequently, of a stable anionic 1,4-diphosphinine II is reported; while II can be used as precursor for 1,4-disubstitution products, its oxidation leads to the formation of the P–P coupling product III.

The facile regioselective synthesis of the P(iii) substituted thiazol-2-thione 2 is presented. Reaction of 2 with hydrogenperoxide-urea, elemental sulfur and selenium resulted in P(v) chalcogenide thiazol-2-thiones 3-5. All compounds were characterized using (31)P, (1)H, (13)C NMR, IR and elemental analyses and, additionally, by the single-crystal X-ray diffraction technique. Oxidative desulfurization of the 5-phosphinoylated thiazol-2-thione 3 using hydrogenperoxide led to the first C-phosphanoyl substituted thiazolium salt (6). Deprotonation of 6 and in situ reaction with the cyclooctadiene rhodium(i) chloride dimer yielded thiazol-2-ylidene rhodium(i) complex 7 which was confirmed by NMR spectroscopy and ESI-MS spectrometry.

Diels–Alder-reactions of a thiazol-2-thione-based, tricyclic 1,4-diphosphinine were investigated, showing that the central aromatic π-system can react with various dienophiles. In one case, photochemical deprotection of the 1,4-diphosphinine was found.

A facile synthetic protocol enables the synthesis of the 4‐phosphanyl‐5‐thiophosphanoyl thiazole‐2‐thione 1 through the selective lithiation of the 5‐thiophosphanoyl thiazole‐2‐thione VIb followed by reaction with chlorodiphenylphosphane. The reaction of 1 with elemental sulfur leads to the PV/PV homochalcogenide thiazole‐2‐thione 2. The heterochalcogenide thiazole‐2‐thione 4 was obtained through the reaction of PIII/PV‐substituted thiazole‐2‐thione VIb with H2O2–urea. All compounds were characterized by 31P, 1H, and 13C NMR spectroscopy, IR spectroscopy, elemental analysis, mass spectrometry, and single‐crystal X‐ray diffraction studies.