Potential energy surface analyses at ab initio levels including electron correlation are reported for the phosphorus analogues of diazonium ions, RXY+ with X,Y=N,P. Protonated, methylated, and phenylated systems are compared with focus on the question regarding end-on versus edge-on coordination. Diphosphonium and phosphoazonium ions are predicted to be more stable toward dissociation than the diazonium ions. The calculated spectroscopic data may assist in their detection. Electronic density distributions of RXY+were analyzed in a variety of ways and with a new energy decomposition method. Charge distributions are contrasted with Lewis notations. CN-and CP-bonded ions show clearly distinct bonding patterns.