Synthesis and characterization of several salts of the heteropoly complexes R2AsMo4O14OH2-, R CH3, C2H5, C6H5, are described. These are some of the first examples of stable organic derivatives of heteropoly anions. The crystal structure of CN3H62CH32AsMo4O14OH-H2O shows the anion to consist of a compact cluster of edge- and face-shared MoO6 octahedra capped by the CH32AsO2 tetrahedron. The new complexes have two other unusual features. First, a uniquely low charge 2- for a polyanion that is stable in aqueous solution pH 2-6 and second, a proton characterized by nmr and ir, that appears to be localized on the oxygen atom that bridges the four molybdenums.