H3O2 Bridging in Trinuclear Clusters

Compound O-OCHjOz), A M-O(H3O2), A M-M, A M-O-O(H3O2), deg. M-O-O-M torsional angle, deg. Reference 

The formation of a hydroxo ligand in the cluster (Eq. 3) is obviously the result of hydrolysis of the triaqua ion (the monocluster ) 

The hydroxo species I reacts with a monocluster to form a dicluster by means of the H3O2 bridging ligand (Eq. 4) 

Similarly, the reaction of several I with each other may form a polymeric chain of clusters ( polycluster ) as in reaction 5 

A further increase in the pH causes deprotonation of a second water ligand of the monocluster  

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