Synthesis and auration of primary and di-primary heteroaryl-phosphines

Convenient high-yield syntheses of the primary and di-primary heteroaryl-phosphines R PH₂ and H₂P-R'-PH₂ (with R = 2-thienyl, 2-furyl, and R' = 2,5-thiophenediyl, 2,5-furandiyl, respectively) are presented. The products and a set of precursor molecules have been characterized by analytical and spectral data, and the crystal structures of selected molecules have been determined: 2-C₄H ₃O-PCl₂, 2,5-(CI₂P)₂C ₄H₂O, 2,5-[(Et₂N)₂P] ₂C₄H₂E (with E = O, S). In the crystals, the two molecules with -PCl₂ substituents adopt trans conformations, while the other two have the -P(NEt₂)₂ groups rotated into a twist conformation. The reaction of the thienyl compounds with tris[(tert-phosphine)gold]oxonium tetrafluoroborates gave almost quantitative yields of the tri- and hexanuclear gold complexes, respectively: {2-C ₄H₃S-P[Au(PR₃)]₃}⁺BF ₄^- and [2,5-{[(R₃P)Au]₃P} ₂C₄H₂S]2⁺(BF₄ ^-)₂, (R = Bu, Ph). The structures of the compounds with R₃P = Bu₃P ligands have been determined. In both cases the [2-C₄H_3/2S-P] units cap triangles of gold atoms in an array that can be described as three [Au(PR₃)]⁺ cations bridged by a phosphido dianion(RP)².