Investigation of the Monomer−Dimer Equilibria of Molybdocenes in Water

Molybdocenes form monomeric and dimeric complexes upon dissolution in water. The solution structures of the molybdocenes at neutral pH are inferred as the monomeric [(CpR) 2 Mo(OH 2 )(OH)] + and the dimeric [(CpR) 2 Mo(μ-OH) 2 Mo(CpR) 2 ] 2+ . The equilibrium constants for the monomer−dimer equilibria were obtained from 1 H NMR dilution studies as K ‘ eq = (7.9 × 10 - 2 ) ± (1.0 × 10 - 3 ) M for R = CH 3 at pD 7 and as K eq = (3.5 × 10 -2 ) ± (1.3 × 10 -3 ) M for R = H at pD 3.5. Qualitatively, the monomer of the CpMe molybdocene is more favored than the Cp analogue, compared to their respective dimers.