Synthesis and Structure of a Molecular Metal Wheel, an Octanuclear Silver(I) Cluster Formed by Racemic 2-Mercaptopropionic Acid and Triphenylphosphine Ligands

The molecular structure of [H4Ag8(2-mpa)6(PPh3)6]·EtOH 1 (2-H2mpa=a racemic form of 2-mercaptopropionic acid), prepared by a 1:5 molar-ratio reaction of polymeric [Ag(2-Hmpa)]n 2 suspended in EtOH with PPh3 in CHCl3, was a wheel-type octanuclear silver(I) cluster; the rim of the wheel was constructed with the outside six Ag(μ3-S)2P units and the axle was formed by the central two Ag(μ3-S)3 units with Ag–Ag separation, 3.122 A.