Rhodium(I) Complexes of the Conformationally Rigid IBioxMe4 Ligand: Isolation of a Stable Low-Coordinate T‑Shaped Complex

The isolation, characterization and reactivity of a T-shaped rhodium­(I) complex containing Glorius’ bioxazoline derived N-heterocyclic carbene ligand IBioxMe4 is described: [Rh­(IBioxMe4)3]­[BArF4] (1). 1 represents a rare example of a solution-stable “naked” 14-electron complex and is characterized in the solid state by highly distorted ligand geometries and Rh···C distances >3.1 Å for the IBioxMe4 alkyl substituents. Consistent with the bulky nature of the NHC ligand, no reaction was observed with excess IBioxMe4, PCy3, or norbornadiene. Reaction of 1 with CO, however, led to coordinatively saturated [Rh­(IBioxMe4)3(CO)]­[BArF4] (2).