Molybdenum complexes tetraphenylporphyrin

Similarly, Hasegawa, Imamura, and Fujimoto have established that molybdenum(V) tetraphenylporphyrins, [MoO(tpp)X] (X = Cl, Br, SCN), are reduced by [K/18-crown-6]C32 in a mixture of dichloromethane and dimethyl sulfoxide, forming the molybdenum(IV) derivative, [MoO(tpp)]. The mechanism for the reduction appears to proceed through an intermediate peroxo complex, [MoO(02)(tpp)], that is stable in solution at -80 °C, but which is converted into [MoO(tpp)] at room temperature. 

A number of unusual structural features have been noted. The ruthenium porphyrin formed by reaction of triruthenium dodecacarbonyl with an N, AT-vinyl-bridged tetraphenylporphyrin involves disruption of a pyrrole C-N bond to give a product in which the ruthenium is bound to two pyrrole N atoms, the C and N atoms of the ruptured pyrrole ring, and two mutually cis carbonyl ligands. The remaining pyrrole N is uncoordinated.613 Mutually cis configurations have also been found for the dicarbonyl complex of molybdenum tetraphenylporphyrin and for some dinitrosyl porphyrins. 

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