Phosphorus‐Atom Transfer from Phosphaethynolate to an Alkylidyne
Mehrafshan G. Jafari, Y.H. Park, Bimal Pudasaini, Takashi Kurogi, Patrick J. Carroll, David M. Kaphan, A. Jeremy Kropf, Massimiliano Delferro, Mu‐Hyun Baik, Daniel J. Mindiola
Abstract
Abstract A low‐spin and mononuclear vanadium complex, ( Me nacnac)V(CO)(η 2 ‐P≡C t Bu) ( 2 ) ( Me nacnac − =[ArNC(CH 3 )] 2 CH, Ar=2,6‐ i Pr 2 C 6 H 3 ), was prepared upon treatment of the vanadium neopentylidyne complex ( Me nacnac)V≡C t Bu(OTf) ( 1 ) with Na(OCP)(diox) 2.5 (diox=1,4‐dioxane), while the isoelectronic ate‐complex [Na(15‐crown‐5)]{([ArNC(CH 2 )]CH[C(CH 3 )NAr])V(CO)(η 2 ‐P≡C t Bu)} ( 4 ), was obtained via the reaction of Na(OCP)(diox) 2.5 and ([ArNC(CH 2 )]CH[C(CH 3 )NAr])V≡C t Bu(OEt 2 ) ( 3 ) in the presence of crown‐ether. Computational studies suggest that the P‐atom transfer proceeds by [2+2]‐cycloaddition of the P≡C bond across the V≡C t Bu moiety, followed by a reductive decarbonylation to form the V−C≡O linkage. The nature of the electronic ground state in diamagnetic complexes, 2 and 4 , was further investigated both theoretically and experimentally, using a combination of density functional theory (DFT) calculations, UV/Vis and NMR spectroscopies, cyclic voltammetry, X‐ray absorption spectroscopy (XAS) measurements, and comparison of salient bond metrics derived from X‐ray single‐crystal structural characterization. In combination, these data are consistent with a low‐valent vanadium ion in complexes 2 and 4 . This study represents the first example of a metathesis reaction between the P‐atom of [PCO] − and an alkylidyne ligand.