Competitive coordination and Lewis-base interactions of amines in supertetrahedral cluster-based materials by a controllable naked T3-InS precursor method: from isolated clusters with various substituted ligands, chains to 3-D open frameworks

Abstract

Investigation of structural evolution and assembly via inter-cluster transformation is highly effective to thoroughly understand the crystal growth process, which is crucial for the accurate synthesis of clusters and cluster-based materials. Herein, we use a ligand-free supertetrahedral (Tn) T3-InS cluster (T3-0) as the precursor to achieve diverse transformation products by tuning the composition of amines and other synthetic parameters, which include not only singly and doubly substituted T3 clusters (T3-1 and T3-2) and a double T3 cluster with six substituting groups (T3-3) but also T3 cluster based chains (T3-4) and three-dimensional cristobalite-topological open frameworks (T3-5). Importantly, we examine the role of amine in transformation processes using HRMS, comparative transformation experiments and DFT theoretical calculations. Notably, the results show that amines with high basicity are more likely to interact with the terminal metals of Tn clusters to produce low dimensional materials, and the competition between amines and cluster derived intermediates is crucial for accurate synthesis of Tn clusters. Then, a reasonable S_N1-like mechanism is proposed for the surface reaction of cluster transformation. This work is significant not only for understanding the role of amines in the nucleation processes of metal chalcogenide Tn clusters but also for providing a novel method for the accurate synthesis of a series of cluster based materials with specific Tn skeletons.