Insertion of CS2 into a Phosphorus-Arsenic Single Bond and Investigations on Phosphane Arsanyldithiocarboxylates

The synthesis and reactivity of sterically demanding phosphaarsanes TerR(1)P-AsR2 (3) is described. These species were selectively synthesized via metathesis reactions of Terstabilized [Ter = 2,6-bis(2,4,6-trimethylphenyl)phenyl] potassium phosphides TerR(1)PK (1) with the N-heterocyclic chloroarsane ClAs{N(tBu)CH2}(2) (2). Conversion of the n-butyl-substituted phosphaarsane 3c with the reactive heterocumulene CS2 leads to an insertion into the P-As bond, yielding the phosphane arsanyldithiocarboxylate TerR(1)P-C(S)S-AsR2 (4c) as a new structural motif. Because full conversion of 3c with CS2 requires long reaction times, an alternative synthetic route is reported herein, involving the conversion of 2 with phosphane dithiocarboxylates TerR(1)-C(S)SK (5), 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.

Automated summary

The synthesis and reactivity of sterically demanding phosphaarsanes were described in this study, with a new structural motif phosphane arsanyldithiocarboxylate being discovered. An alternative synthetic route was reported to enable access to a wider range of phosphane arsanyldithiocarboxylates. The interpnictogen dithiocarboxylates showed an interesting bonding situation with significantly elongated As-S bond due to negative hyperconjugation within the molecule.