Novel chloride-centered Ag18 clusters featuring a cuboctahedral Ag12 skeleton

Two novel chloride-centered Ag18 clusters with the same framework but different supporting phosphines are synthesized by the reaction of PhCCAg, AgSbF6, PPh3 (or P(p-Tol)3), and NaBH4 in CH2Cl2, followed by the addition of PhCCH and NEt3. The inner twelve Ag atoms of these two clusters are arranged in a rare cuboctahedral structure, which can be rationalized by considering a ligand effect. Through careful analysis, we find that the central chloride arises from a generally ignored but nonetheless existing reaction between CH2Cl2 and NEt3, which is well recognized as the Menshutkin reaction. This research provides insights into the dependence of the cluster structure on the nature of the ligand and into the cluster formation mechanism of the Menshutkin reaction.