Preparation and Properties of Sodium Dimethyldithioarsinate Dihydrate, Me 2 AsS 2 Na·2H 2 O, and Palladium(II) Dimethyldithioarsinate, (Me 2 AsS 2 ) 2 Pd

Palladium(II) acetate in non‐deaerated chloroform splits Bunsen ’s cacodyl disulfide, Me 2 As(S)–S–AsMe 2 , giving the complex (Me 2 AsS 2 ) 2 Pd, slightly soluble in chloroform, and the arsonium ion Me 2 As: + . However, after a few minutes the complex reacted giving Me 2 As(S)–O–As(S)Me 2 and other, so far unidentified compounds. Therefore, the complex (Me 2 AsS 2 ) 2 Pd was prepared from sodium dimethyldithioarsinate dihydrate, Me 2 AsS 2 Na · 2H 2 O, and palladium(II) acetate. (Me 2 AsS 2 ) 2 Pd reacts with Pd II and Ph 3 P in a different way compared to other (Me 2 AsS 2 ) x M (M = heavy metal cation) and (Me 2 PS 2 ) 2 Pd. The reaction of equimolar quantities of Me 2 AsS 2 Na · 2H 2 O and Ph 3 P under argon involved four consecutive reactions with Me 2 As–O–AsMe 2 and Me 2 AsS 2 Na as the final products. The salt Me 2 AsS 2 Na · 2H 2 O has been structurally characterized: triclinic, P \bar{1} , a = 6.0285(2) Å, b = 6.5552(2) Å, c = 12.1480(4) Å, α = 98.282(2) ό , β = 93.994(3) ό , γ = 115.951(3) ό , V = 422.38(3) Å 3 , Z = 2, R 1 = 0.0207, wR 2 = 0.0414.