Molybdenum hydrolysis rate

Fig. 8. The Fe protein cycle of molybdenum nitrogenase. This cycle describes the transfer of one electron from the Fe protein (F) to one afi half of the MoFe protein (M) with the accompEmying hydrolysis of 2MgATP to 2MgADP + 2Pf. The rate-determining step is the dissociation of F (MgADP)2 from M,rf. Subscript red = reduced and ox = oxidized.

Aquation of dichromate exhibits general-acid catalysis, which may operate by protonation of the bridging oxygen atom. The mechanism of aquation of the peroxoanion [0(02)4] has been investigated by kinetic and tracer experiments. The tracer results, and the observed effects of added inhibitors on reaction rates, show that the rate law for aquation is deceptively simple. Base hydrolysis of [Mo7024] to [Mo04] takes place by successive bimolecular attacks by hydroxide at the molybdenum atoms. ... 

Fe-Cr-Ni-Mo class of steels on crevice corrosion initiation is important. It has been shown that iron, chromium, nickel and Mo improve the resistance of steels to crevice corrosion [7]. Crevice corrosion is not usually observed with 6% molybdenum. The effect of chromium can be harmful if it increases the acidity in the crevice by hydrolysis. At a higher chromium concentration, it generally increases the stability of the passive film, lowers the pH below that required for crevice to initiate, and reduces the passive current density. The rate of entry of chromium ions in the crevice is, therefore, minimized, hence hydrolysis which causes acidic conditions in the crevice is minimized by chromium. 

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