A Novel Type of [Mo3O9(L*)]5− Anion in the Structure of an Ammonium−Guanidinium Salt of a MoVI Complex with 1-Hydroxyethylidenediphosphonic Acid (H4L)

The synthesis and X-ray analysis of (NH4)2[C(NH2)3]3[MoO3O9(L*)] 2.5H2O have been carried out (L* = L5−); the trinuclear anion has an unusual structure with a different number of terminal oxygen atoms in the ’yl’ groups at the molybdenum atoms (two MoO2 groups and the MoO3 group), where pairs of MoO6 octahedra share a common face or vertex; the structure of the [Mo3O9(L*)]5− anion is similar to that of one half of the [Mo6O17(L2*)]8− hexanuclear anion, in which the central bridging oxygen atom Oc is substituted by a terminal Ot.