Heavily π-Bond-Loaded Tungsten Phosphonio−Alkylidyne Complexes via a Domino Transylidation Cascade at (Organoimido)tungsten Tetrachlorides

Abstract

Transylidation reactions of (arylimido)tungsten tetrachlorides [W(NR)Cl 4 ] with 7 equiv of Ph 3 P-CH 2 lead to the tetrahedral complexes [W(NR)(C-PPh 3 )(CH-PPh 3 ) 2 ] (R = Dip (1), Mes (2)), exhibiting one metal-nitrogen and three metal-carbon multiple bonds. The crystal structure analysis of 1 presents the first example of a terminal phosphonio-methylidyne functionality, [M≡C-PR 3 ] ↔ [M=C=PR 3 ], formed via a transylidation reaction. Due to the high level of π-bond competition of four π-donor ligands, the M=C=P axis is considerably bent: 154.0(4)°.