Synthesis of dinuclear gold-(I) and -(II) complexes by reaction [Au-2(I){mu-(CH2)(2)PPh2}(2)] with protonic acids

The reaction of the bis(ylide) gold complex [Au-2{mu-(CH2)(2)PPh2}(2)] with strong acids (such as HClO4) in the presence of diphosphines L-L afforded a mixture of heterobridged gold(I) complexes [Au-2{mu-(CH2)(2)PPh2}(mu-L-L)](+) (L-L = Ph2PCH2CH2PPh2 or Ph2PCH2PPh2) and [PPh2Me2](+). After addition of Li(tcnq), [Au-2{mu- (CH2)(2)PPh2}(mu-L-L)](2)[ClO4][tcnq] were obtained pure (tcnq = 7,7,8,8-tetracyanoquinodimethane). The crystal structure of the Ph2PCH2CH2PPh2 derivative shows an intramolecular gold-gold distance of 3.1294(9) Angstrom. The use of weak protonic acids such as pyridine-2-thiol (C5H5NS) or 2-sulfanylbenzothiazole (C7H5NS2), in the presence of atmospheric oxygen, led to complexes of gold(II). The crystal structure of [Au-2(II){mu-(CH2)(2)PPh2}(2)(C5H4NS)(2)]shows a gold-gold bond length of 2.6686(13) Angstrom.