Bis(4,4′-bipyridinium) bis(μ5-hydrogen phosphate)pentakis(μ2-oxido)decaoxidopentamolybdate dihydrate

Abstract

The title compound, (bipyH2)2[H2Mo5O23P2]·2H2O or (C10H10N2)2[Mo5O15(HPO4)2]·2H2O, contains the heteropoly­anion [P2Mo5O21(OH)2]4−, two diprotonated 4,4′-bipyridine (bipy) molecules as cations and two water mol­ecules. The heteropolyanion is built up from five MoO6 octa­hedra sharing four common edges and one common corner. The heteropolyanion has approximate noncrystallographic twofold rotation symmetry, the axis running through one Mo and one O atom. Five bridging O atoms between molybdenum centers connect the distorted MoO6 octa­hedra to form a ring system, with ten Mo—O distances having an average value of 1.923 (2) Å. Six O atoms of the PO3(OH) tetra­hedra above and below the ring stabilize the polyanionic framework. The ten Mo—OP bond lengths differ markedly, between 2.219 (2) and 2.461 (2) Å. The ten short terminal Mo—O distances average 1.706 (2) Å. The P—O bond lengths range between 1.513 (2) and 1.567 (2) Å. The crystal packing exhibits a great number of N—H⋯O and O—H⋯O inter­molecular classical hydrogen bonds, which link the cations, water mol­ecules and polyanions to form a three-dimensional framework.