Insertion of CS into a Phosphorus-Arsenic Single Bond and Investigations on Phosphane Arsanyldithiocarboxylates.

The synthesis and reactivity of sterically demanding phosphaarsanes TerRP-AsR () is described. These species were selectively synthesized via metathesis reactions of Ter-stabilized [Ter = 2,6-bis(2,4,6-trimethylphenyl)phenyl] potassium phosphides TerRPK () with the N-heterocyclic chloroarsane ClAs{N(Bu)CH} (). Conversion of the -butyl-substituted phosphaarsane with the reactive heterocumulene CS leads to an insertion into the P-As bond, yielding the phosphane arsanyldithiocarboxylate TerRP-C(S)S-AsR () as a new structural motif. Because full conversion of with CS requires long reaction times, an alternative synthetic route is reported herein, involving the conversion of with phosphane dithiocarboxylates TerR-C(S)SK (), enabling synthetic access to a wider range of phosphane arsanyldithiocarboxylates. These interpnictogen dithiocarboxylates show an interesting bonding situation with a significantly elongated As-S bond due to negative hyperconjugation within the molecule. All products along the reaction path were fully characterized.