Synthesis and Characterization of Tungsten Alkylidene and Alkylidyne Complexes Supported by a New Pyrrolide-Centered Trianionic ONO3– Pincer-Type Ligand

Synthetic protocols for a pyrrolide-centered ONO3– trianionic pincer-type ligand are presented. Treating (tBuO)3W≡CtBu with the proligand [pyr-ONO]H3 (2) results in the formation of the trianionic pincer alkylidene complex [pyr-ONO]W═CHtBu(OtBu) (3). Addition of a mild base to complex 3 provides the trianionic pincer alkylidyne complex {MePPh3}{[pyr-ONO]W≡CtBu(OtBu)} (4). All new compounds were characterized by NMR spectroscopy, combustion analysis, and, in the case of complex 4, single-crystal X-ray crystallography. DFT calculations performed on 4 provide insight into its electronic structure and indicate that the HOMO is ligand-based and localized on the pyrrolide π orbitals.