The reaction of 2 with four equivalents of Ph3PBr2 showed sequential metathesis (see Figure , SI, for spectra of intermediates) to yield the fully substituted product [(P(NPPh3))4(NMe)6][Br]4 (3, Scheme 3). The 31 P NMR spectrum of the cation shows two resonances of equal integration, corresponding to the expected A4X4 spin system and the 1 H NMR spectrum confirmed the loss of all silyl resonances. Single crystal X-ray diffraction unambiguously confirms the molecular structure of 3 in the solid state, but positional disorder arising from four monoatomic anions packing with a 174 atom-large cation significantly mars data quality and precludes discussion of metric parameters (Figure , SI).