Dodecamolybdotetrakis(organoarsonates) and the structure of a neutral zwitterionic heteropoly complex

Article abstract of DOI:10.1021/ic50224a035

Several salts of the herteropoly molybdoarsonate anions [(RAs)₄MO₁₂O₄₆]^4- (R = CH₃, C₆H₅, p-C₆H₄NH₃⁺, C₂H₄OH) have been prepared and characterized by spectroscopic techniques. The derivative with R = p-C₆H₄NH₃⁺ is stable to at least 250°C and shows anomalous solubility behavior in mixed solvents. The structure of [(p-H₃NC₆H₄As)₄Mo₁₂O ₄₆]·6H₂O·10CH₃CN (Fdd2, a = 38.916 (6) A?, b = 38.972 (7) A?, c = 11.901 (2) A?, Z = 8) has been determined by single-crystal X-ray diffraction and refined to final consistency indices R and R_w of 0.069 and 0.062, respectively. The metal oxide portion of the structure is similar to that in (NH₄)₄H₄As₄Mo₁₂O ₄₆·H₂O and consists of four groups of three MoO₆ octahedra, which share edges within each group and corners with neighboring groups. The octahedra are bridged by four tetrahedral p-H₃⁺NC₆H⁴As groups. The complexes are held together by H₂O molecules, which are presumably hydrogen bonded to the nitrogens of the organic groups, and by CH₃CN molecules, which lie in diagonal rows between the complexes.