Synthesis and reactivity of phosphine-stabilized phosphoranimine cations, [[[R.sub.3]P.P[R.sub.2]-[double bond]NSi[Me.sub.3]].sup.+]

A series of phosphine-stabilized phosphoranimine cations [[[R.sub.3]P.P[R.sub.2]-[double bond]NSi[Me.sub.3]].sup.+] are prepared and the reactivities are studied. The density functional theory studies have shown that the difference in the [super 1][J.sub.pp] couplings are related to the electronegativity of the R- substituents at the phosphoranimine phosphorous center rather than the strength of the donor-acceptor P-P bond.