Access and unprecedented reaction pathways of Li/Cl phosphinidenoid iron(0) complexes
Complexes [Fe(CO)4(RPCl2)] (2) (a: R = CPh3, b: R = tBu) were used to generate the first examples of phosphinidenoid iron(0) complexes [Li(12-crown-4)(solv)n][Fe(CO)4(RPCl] (3a,b), characterized by NMR spectroscopy. The bonding situation of 3 was analyzed for a P-Me model complex using DFT calculations. Complex 3a (R = CPh3) reacted with H2O and MeOH to give selectively O–H bond insertion products 5 and 7; for the case of H2O, a multistep electrophilic reaction is supported by detailed DFT calculations. Clear-cut evidence for an unprecedented electrophilic reactivity of 3a was obtained as a reaction with MeLi led to P-chloro substitution. The intermediately formed phosphanido complex [Fe(CO)4(Ph3CPMe)] (8) was quenched with HCl or MeOTf to furnish neutral iron(0) complexes 9 and 10.