Formation of a trimethyldihydroperimidinium cation from proton sponge [1,8-bis(dimethylamino)naphthalene] during base-promoted reactions of rhodium and ruthenium complexes

Proton sponge, in the presence of mer-RhCl3(dmso)3 or [RuCl(dppb)]2(µ-Cl)3(dmso = dimethyl sulphoxide, dppb = Ph2P[CH2]4PPh2), generates (via a net hydride loss from one methyl group) the 1,1,3-trimethyl-2,3-dihydroperimidinium cation, which is isolated as the counter-ion in complexes containing the anions trans-[RhCl4(dmso)2]– and {[RuCl(dppb)]2(µ-Cl)3}–.