Sulfinylaminemetathesis at oxo metal species - convenient entry into imido metal chemistry

Abstract

The exchange of terminal metal oxo functionalities by N-organo and N-sulfonylimido functionalities viametathesis with bent, thus very reactive sulfinyl amines R-NSO and sulfinyl sulfonylamides R-SO₂-NSO is described. It is demonstrated that in many cases sulfinyl amine metathesis offers a more convenient entry into imido complex synthesis than the much better investigated isocyanate metathesis at oxo complexes or condensation reactions with amines and silylated amines. Improved syntheses for some known key compounds and several new complexes of the type [V(NR)Cl₃] and [M(NR)₂Cl₂] (M = Cr, Mo, W) are described. Emphasis is put on the synthesis of formerly unknown base free Lewis acids with electron-withdrawing N-substituents such as haloaryl and sulfonylaryl. Surprisingly, even [CrO₂Cl₂] is selectively transformed by sulfinylamines into aryl imido derivatives without any reduction by sulfur dioxide. The molecular structures of novel haloaryl imido complexes [Cr(NAr)₂Cl₂] Ar = C₆F₅ and 2,4,6-Cl₃C₆H₂ as determined by X-ray crystallography are reported.