Is the phosphaethynolate anion, (OCP)~?, an ambident nucleophile? A spectroscopic and computational study?

摘要

The reactivity of Na(OCP) was investigated towards triorganyl compounds of the heavier group 14 elements (R_3EX R = Ph or ~iPr; E = Si, Ge, Sn, Pb; X = Cl, OTf). In the case of E = Si two constitutional isomers were formed and characterised in situ: R_3Si-O-CuP is the kinetic and R_3Si-PvCvO is the thermodynamic product, representing experimental evidence of the ambident character of the (OCP)? anion. Applying theoretical calculations and spectroscopic methods, the compound previously reported as ~iPr_3Si-O-CuP can now unambiguously be identified as ~iPr_3Si-PvCvO. The heavier analogues form exclusively the phosphaketene isomer R_3E-PvCvO (E = Ge, Sn, Pb). DFT calculations were performed to gain deeper insight into the bonding and thermodynamic stability of these compounds.