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-C4H3O–PCl2, 2,5-(Cl2P)2C4H2O, 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-C4H3S–P[Au(PR3)]3}+BF4− and [2,5-{[(R3P)Au]3P}2C4H2S]2+(BF4−)2, (R = tBu, Ph). The structures of the compounds with R3P = tBu3P ligands have been determined. In both cases the [2-C4H3/2S–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−.