An unconventional route to [(Me₃Si)₂HCPCl₂W(CO)₅] and its conversion to the structurally characterized P-chalcogenides (Me₃Si)₂HCP(X)Cl₂[X = S, Se]

Heating a solution of 2H-azaphosphirene complex 1 in CCl₄ at 75 °C for 2 h yields selectively [(Me₃Si)₂HCPCl₂W(CO)₅] (6). Attempts to convert this cleanly to the corresponding P-oxide [(Me₃Si)₂HCP(O)Cl₂] (7) were unsuccessful and even the reaction of (Me₃Si)₂HCPCl₂ (9) with the urea–H₂O₂ adduct in toluene led only to the formation of the hydrolysis product [(Me₃Si)₂HCP(O)(OH)Cl] (8). However, 9 could be selectively converted to 7 by the use of DMSO. In contrast, the related chalcogenides [(Me₃Si)₂HCP(S)Cl₂] (10) and [(Me₃Si)₂HCP(Se)Cl₂] (11) could be synthesized from either 6 or 9 with elemental sulfur and selenium, respectively. All products were characterized by NMR and MS and, additionally 6, 8, 10 and 11 by single crystal X-ray studies. Compound 10 represents the first example of a structurally characterized thiophosphonic dihalide.