Reaction of N≡W(O(t)Bu)3 with σ3λ5-phosphoranes. The [2 + 2] cycloaddition across the W≡N triple bond results in the first representative of an inorganic four-membered metallacycle with conjugated endo- and exocyclic double bonds

The reactions of N≡W(O(t)Bu)(3) with the low-coordinate phosphorus compounds (Me(3)Si)(2)NP(NSiMe(3))(2) (I) and (Me(3)Si)(2)NPS(N(t)Bu) (II) were studied. Quantum chemical calculations were used to determine why Mo- and W-containing compounds with the same composition have different molecular structures.