Formation of a Uranium-Bound η1-Cyaphide (CP–) Ligand via Activation and C–O Bond Cleavage of Phosphaethynolate (OCP–)

Reaction of the trivalent uranium complex [(( Ad,Me ArO) 3 N)U(DME)] with [Na(OCP)(dioxane) 2.5 ] and 2.2.2-crypt yields the μ-oxo-bridged, diuranium complex [Na(2.2.2-crypt)][{(( Ad,Me ArO) 3 N)U(DME)}(μ-O){(( Ad,Me ArO) 3 N)U(CP)}] ( 1 ). Complex 1 features an asymmetric, dinuclear U IV –O–U IV core structure with a cyaphide (CP – ) anion η 1 - C P bound to one of the U ions, and a κ 2 - O DME coordinated to the other. The CP – ligand is unprecedented in uranium chemistry and is formed through reductive C–O bond cleavage of the phosphaethynolate anion (OCP – ). An analogous reaction was performed starting from the tetravalent uranium halide complex [(( Ad,Me ArO) 3 N)U(DME)(Cl)]. This salt metathesis approach with [Na(OCP)(dioxane) 2.5 ] results in formation of the mononuclear complex [(( Ad,Me ArO) 3 N)U(DME)(OCP)] ( 2 ) with an OCP – anion bound to the uranium(IV) center via the oxygen atom in an η 1 - O CP fashion.