Reactions between carbonylhydridotris(triphenylphosphine)iridium(I) and difluorophosphine oxide, sulphide, and selenide: identification of ionic intermediates

Abstract

Carbonylhydridotris(triphenylphosphine)iridium(I)(1) reacts with PF₂HY (Y = O, S, or Se) at 190 K in CH₂Cl₂ to give [Ir(CO)H₂(PPh₃)₃][PF₂Y](2), identified by n.m.r. spectroscopy. When the solutions were allowed to warm above 220 K, PPh₃ was liberated and complexes [Ir(CO)H₂(PPh₃)₂(P′F₂Y)] were formed [Y = Se, (3a); S, (3b); or O, (3c)]. Complexes (3a) and (3b) were initially produced in two isomeric forms, with the PPh₃ groups mutually cis or mutually trans; the cis isomer slowly isomerised to the trans isomer at room temperature. For complex (3c)(Y = O) only the trans isomer was detected. The complex [Ir(CO)H(PPh₃)₂(P′F₃)] was formed as a by-product in these reactions, and its n.m.r. parameters are reported. The implications of the formation of ionic intermediates in the reactions of (1) are briefly considered in relation to mechanisms of related reactions that are usually considered to involve initial loss of PPh₃ from (1).