Electrophilic Aromatic Substitution Reactions of a Tungsten- Coordinated Phosphirenyl Triflate

The phosphirenyl cation complex [W(CO)5{PC(Ph)C(Ph)}]+ (2) is formed by chloride abstraction from the chlorophosphirene complex [W(CO)5{P(Cl)C(Ph)C(Ph)}] (1) with excess AlCl3. The phosphirenyl triflate complex [W(CO)5{P(OSO2CF3)C(Ph)C(Ph)}] (3) is formed by reaction of the chlorophosphirene complex with AgOSO2CF3 and is in equilibrium with and typically reacts in the same fashion as the phosphirenyl cation. Reaction of 3 with diethylaniline or anisole leads to electrophilic aromatic substitution preferentially at the para position. Reaction with N,N-dimethyl-p-toluidine, in which the para position is blocked, leads to exclusive ortho substitution. The resulting 1,2-substituted arene can adopt a P,N bidentate coordination mode if a CO is removed from tungsten via photolysis. Compound 3 reacts with aromatic heterocycles thiophene, furan, and pyrrole, leading exclusively to substitution in the 2 position, with no evidence for P–S, P–O, or P–N bond formation. Reaction with indole led to substitution at the 3...