Isolation, optical properties and core structure of a water-soluble, phosphine-stabilized [Au9]3+ cluster

Abstract

A water-soluble, crystalline Au9 cluster compound stabilized with sodium (m-sulfonatophenyl) diphenylphosphine (TPPMSNa) was obtained during the NaBH4 reduction of [Au(TPPMSNa)Cl]·H2O in ethanol. Characterization by optical extinction spectroscopy, single-crystal X-ray diffraction in combination with energy dispersive X-ray diffraction led to the preliminary formula Na(8-x)[Au9(TPPMS) 8]Cl(3-x) · nH2O (0 ≤ x ≤ 3, n ≈ 16) with the cluster core in crown conformation. 31P{ 1H} nuclear magnetic resonance spectroscopy revealed one singlet at 57:3 ppm. This is the first example where gold clusters stabilized by TPPMSNa formed crystals which where suitable for core structure determination. © 2013 Verlag der Zeitschrift für Naturforschung, Tübingen.