Observations on the mass spectra of mixed lead/methanol cluster ions, Pb-M(CH3OH)(N)(+), for M less than or equal to 4 and N less than or equal to 10, shaw evidence of a bimolecular dehydration reaction which is promoted when N greater than or equal to 3. The experimental results are interpreted in terms of a metal atom insertion reaction, and the dehydration step is confirmed through the use of isotopes. An analogy is drawn between this reaction and those observed for solution phase plumboxanes.