Synthesis of a C-pyridine-substituted 2H-1,3,2-diazaphosphole complex and subsequent oxidation to its PV-sulfide and PV-selenide derivatives

Thermal ring opening of 2H-azaphosphirene tungsten complex 1 in the presence of 2-piperidino carbonitrile and 2-cyanopyridine furnished selectively the 2H-1,3,2-diazaphosphole tungsten complex 3. Liberation of the diazaphosphole ligand by applying various decomplexation reagents failed. However, the corresponding PV-sulfide 4 and PV-selenide 5 were obtained by oxidative decomplexation using elemental sulfur and selenium. All products were characterized by NMR spectroscopy and MS spectrometry. The constitution of 3 and 5 could also be established by single crystal X-ray diffraction.