A new ONO3- trianionic pincer-type ligand for generating highly nucleophilic metal-carbon multiple bonds.

Appending an amine to a C═C double bond drastically increases the nucleophilicity of the β-carbon atom of the alkene to form an enamine. In this report, we present the synthesis and characterization of a novel CF3–ONO3- trianionic pincer-type ligand, rationally designed to mimic enamines within a metal coordination sphere. Presented is a synthetic strategy to create enhanced nucleophilic tungsten–alkylidene and −alkylidyne complexes. Specifically, we present the synthesis and characterization of the new CF3–ONO3- trianionic pincer tungsten–alkylidene [CF3–ONO]W═CH(Et)(OtBu) (2) and −alkylidyne {MePPh3}{[CF3–ONO]W≡C(Et)(OtBu)} (3) complexes. Characterization involves a combination of multinuclear NMR spectroscopy, combustion analysis, DFT computations, and single crystal X-ray analysis for complexes 2 and 3. Exhibiting unique nucleophilic reactivity, 3 reacts with MeOTf to yield [CF3–ONO]W═C(Me)(Et)(OtBu) (4), but the bulkier Me3SiOTf silylates the tert-butoxide, which subsequently undergoes isobutylene ex...