Reactions of 2-arsa- and 2-stiba-1,3-dionato lithium complexes with group 4–7 metal halides

The reactions of a range of 2-arsa- and 2-stiba-1,3-dionato lithium complexes with group 4–7 metals have been investigated. These have given rise to several complexes in which an arsadionate acts as a chelating ligand; [V{η2-O,O-OC(But)AsC(But)O}3], [M{η2-O,O-OC(But)AsC(But)O}2(DME)], M=Cr or Mn; or as an η1-As-diacylarsenide, [MnBr(CO)4{As[C(O)But]2Li(DME)}]2. In addition, reactions of lithium arsadionates with TaCl5 have led to metal mediated arsadionate decomposition reactions and arsadionate oxidative coupling reactions to give the known arsaalkyne tetramer, As4C4But4, and the new tetraacyldiarsane, [{As[C(O)Mes]2}2] Mes=mesityl, respectively. The treatment of several lithium arsadionates with [MoBr2(CO)2(PPh3)2] has also initiated arsadionate decomposition reactions and the formation of the metal carboxylate complexes, [MoBr(CO)2{η2-O2C(R)}(PPh3)2] R=But, Ph, Mes. The X-ray crystal structures of six of the prepared complexes are discussed.