Part~I. Diphosphate complexes of polyoxotungstates and polyoxomolybdates. Part~II. Structures of potassium(3) (arsenic(2) (arsenate) molybdenum(12) oxygen(36)) . 4 water, potassium(10) (hydrogen(2) tungsten(12) oxygen(42)) . 7.5 water, and cesium(6) (mol

In Part I, four new structural types of heteropolyanions are presented. They are diphosphate complexes of polyoxotungstates and polyoxomolybdates. The hetero groups are diphosphate (O{dollar}sb3{dollar}POPO{dollar}sb3sp{lcub}4-{rcub}{dollar}) and its hydrolytically stable analogs methylenediphosphonate (O{dollar}sb3{dollar}PCH{dollar}sb2{dollar}PO{dollar}sb3sp{lcub}4-{rcub}{dollar}) and (dimethylamino) methylenediphosphonate (O{dollar}sb3{dollar}PCHN(CH{dollar}sb3)sb2{dollar}PO{dollar}sb3sp{lcub}4-{rcub}{dollar}), respectively.; The first structural type has the formula {dollar}rmlbrack(Osb3PXPOsb3)sb4Wsb{lcub}12{rcub}Osb{lcub}36{rcub}rbracksp{lcub}16-{rcub} (X = CHsb2, O){dollar}. The two anions ((O{dollar}sb3{dollar}POPO{dollar}sb3)sb4{dollar}W{dollar}sb{lcub}12{rcub}{dollar}O{dollar}sb{lcub}36{rcub}rbracksp{lcub}16-{rcub}{dollar} (I) and ((O{dollar}sb3{dollar}PCH{dollar}sb2{dollar}PO{dollar}sb3)sb4{dollar}W{dollar}sb{lcub}12{rcub}{dollar}O{dollar}sb{lcub}36{rcub}sp{lcub}16-{rcub}{dollar} (II) are isostructural and are formed in aqueous solution. The open cyclic structure of I and II is an unusual new polyoxometalate conformation with external heterogroups.; The second structural type, ((O{dollar}sb3{dollar}PCH{dollar}sb2{dollar}PO{dollar}sb3{dollar})Mo{dollar}sb6{dollar}O{dollar}sb{lcub}18{rcub}{dollar}(H{dollar}sb2{dollar}O){dollar}sb4rbracksp{lcub}4-{rcub}{dollar} (III), is also formed in aqueous solution. It consists of a six-membered ring of MoO{dollar}sb6{dollar} octahedra, which alternate in sharing edges and corners. Based on spectroscopic evidence the pyrophosphate analog (IV) almost certainly has the same structure. The molybdenum analogs of I and II, ((O{dollar}sb3{dollar}PCH{dollar}sb2{dollar}PO{dollar}sb3)sb4{dollar}Mo{dollar}sb{lcub}12{rcub}{dollar}O{dollar}sb{lcub}36{rcub}rbracksp{lcub}16-{rcub}{dollar} (V) and ((O{dollar}sb3{dollar},POPO{dollar}sb3)sb4{dollar}Mo{dollar}sb{lcub}12{rcub}{dollar}O{dollar}sb{lcub}36{rcub}rbracksp{lcub}16-{rcub}{dollar} (VI) are proposed. Anions IV and VI are possible intermediates in the molybdate-catalyzed hydrolysis of pyrophosphate. The third structural type, ( ((O{dollar}sb3{dollar}PCHN(CH{dollar}sb3) sb2{dollar}PO{dollar}sb3{dollar})W{dollar}sb2{dollar}O{dollar}sb6rbracksp4-)infty{dollar}, is formed in aqueous solution and represents a novel linear polymeric heteropolyanion of tungsten. It consists of negatively-charged chains with {dollar}rmlbrack (Osb3PCHN(CHsb3)sb2POsb3)Wsb2Osb6rbracksp{lcub}4-{rcub}{dollar} (VII) as the repeat unit.; The fourth structural type, ((O{dollar}sb3{dollar}POPO{dollar}sb3{dollar})Mo{dollar}sb{lcub}18{rcub}{dollar}O{dollar}sb{lcub}54{rcub}rbracksp{lcub}4-{rcub}{dollar} (VIII), is formed in a mixed aqueous-organic solvent. It is based on fusion of two B-type PMo{dollar}sb9{dollar}O{dollar}sb{lcub}34{rcub}{dollar} - moieties. Consequently the enclosed pyrophosphate anion is constrained to have a linear P-O-P bond (177.7{dollar}spcircpm 1.3{dollar}) and an eclipsed conformation. The green one-electron reduced species ((O{dollar}sb3{dollar}POPO{dollar}sb3{dollar})Mo{dollar}sb{lcub}18{rcub}{dollar}O{dollar}sb{lcub}54{rcub}rbracksp{lcub}5-{rcub}{dollar} (VIII{dollar}spprime{dollar}) and the blue two-electron reduced species ((O{dollar}sb3{dollar}POPO{dollar}sb3{dollar})Mo{dollar}sb{lcub}18{rcub}{dollar}o{dollar}sb{lcub}54{rcub}rbracksp{lcub}6-{rcub}{dollar} (VIII{dollar}sp{lcub}primeprime{rcub}{dollar}) show single {dollar}sp{lcub}31{rcub}{dollar}p NMR resonances. The ESR spectrum of afrozen solution (77 K) of VIII{dollar}spprime{dollar} is a barely resolved axial pattern.; In Part II the crystal structures of K{dollar}sb3{dollar} (As{dollar}sb2{dollar}(AsO{dollar}sb4{dollar})Mo{dollar}sb{lcub}12{rcub}{dollar}O{dollar}sb{lcub}36{rcub}{dollar}), K{dollar}sb{lcub}10{rcub}{dollar} (H{dollar}sb2{dollar}W{dollar}sb{lcub}12{rcub}{dollar}O...