Toward an Understanding of Ligand Selectivity in Nanocluster Synthesis

Abstract

We performed scalar relativistic density functional theory (DFT) calculations using the projector augmented wave scheme (PAW) to examine the reactivity and selectivity of diphosphine ligands LM, with the formula PH2(CH2)MPH2 (spacer M = 3, 5), toward small-sized cationic Aun (n = 7–11) nanoclusters. By isolating the ligand-induced contribution to the stability condition, we show that such interaction selectively stabilizes the cationic Au11 cluster. Furthermore, we find that L5 with the longer spacer is more capable than L3 of relieving the strain imposed on the spacer by bidentate binding to gold clusters, which have relatively small Au–Au bond lengths. Thus L5 can interact effectively with gold clusters of various sizes, but L3 can do so only with a selected few. This result demonstrates the size-selecting power of L3 toward small gold clusters such as Au113+. To further test the validity of our results we have extended the calculation to a larger cluster, Au13, and also considered the case of a ligand ...