PNNL

Abstract

Because of the strong relativistic effects, the chemistry of gold differs substantially from the rest of the coinage metals. [1-6] The relativistic stabilization of the 6s orbital in gold gives rise to an anomalously high electron affinity of Au, which has been compared to the halogens, [5,7,8] such as in the recently predicted tetraaurides [MAu4] (M=Ti, Zr, Th).[9] The most remarkable chemistry of gold is the isolobal analogy between a gold phospane unit {AuPR3} and a hydrogen atom, [10-12] which has been exploited to bring out tetra- and hyper-coordination in compounds, such as [C(AuPR3)4] and [C(AuPR3)5]+[13-17]. Herein we show that a single gold atom can also exhibit chemistry analogous to the hydrogen atom. We report experimental and theoretical evidence that a serious of Si-Au clusters, [SiAun] (n=2-4), are structurally and electronically similar to SiHn. Photoelectron spectroscopy (PES) of corresponding [SiAun]- anions reveals that [SiAu4] has a large energy gap of 2.4eV, thus indicating extremely chemically stable molecule.