SYNTHESIS AND X-RAY STRUCTURE OF TETRABUT YLAMMONIUM ARSENATO)BIS(MU-PEROXO)BIS(OXOPEROXOTUNGSTATE)(2-) AND OF A METHYLARSENATO ANALOG - NOVEL ACTIVE OXYGEN-TO-OLEFIN TRANSFER AGENTS

Novel peroxotungstate species are formed in the ''H2WO4/H2O2-H2O/Na2HA sO4.7 H2O or Na2CH3AsO3.6 H2O'' systems. They can be isolated as onium salts: complex [(n-C4H9)4N]2[HAsO4{W2O2(mu-O2)2(O2)2}]: monoclinic, P 2(1)/n, Z = 4, a = 15.832(3), b = 17.170(3), c = 18.070(6) angstrom, beta = 113.81(2)-degrees; complex [(n-C4H9)4N]2[CH3AsO3{W2O2(mu-O2)2(O 2)2}]: triclinic, P 1BAR, Z = 2, a = 10.420(3), b = 12.658(2), c = 19. 426(4) angstrom, alpha = 108.42(2), beta = 93.49(2), gamma = 96.26(2)- degrees. These polyanions have one nonbridging and one bridging peroxo group on each W center. Structural features compare well with those o f previously described complexes, [(n-C6H13)4N]3[PM4O24] (M = Mo or W) and [(n-C4H9)4N]2[HPW2O14]. (R)-(+)-limonene is stoichiometrically ep oxidized at room temperature. The results show an effect of the assemb ling ligand.