Molybdenum(V) on an Oxide String. Formation and Solution Stability of the Linear Complex (μ-trans-Dioxo(tetraphenylporphyrinato)molybdenato(V))bis(oxo(tetraphenylporphyrinato)molybdenum(V)) Perchlorate

The unusual linear trinuclear complex [Mo3O4(TPP)3]+ is formed in solution upon the reaction of [MoO(TPP)(OClO3)] with {[MoO(TPP)]2O}, and an equilibrium between [Mo3O4(TPP)3]+ and its constituent species is rapidly established. Spectrophotometric experiments suggest that [Mo3O4(TPP)3]+ is the predominant species found in solutions resulting from the mixture of [MoO(TPP)(OClO3)] and {[MoO(TPP)]2O}, and its formation is strongly favored (log K = 5.5 ± 0.5 M-1). No evidence of higher oligomers has been observed. A mechanism for the formation of [Mo3O4(TPP)3]+ by the controlled hydrolysis of [MoO(TPP)(OClO3)] is proposed.