Syntheses,Structures And Properties Of Silver-based Metal Hydride Clusters

Nanoclusters,which sizes are between small moleculars and nanoparticles,are consisted strongly bounds of tens to several thousands of atoms.They can crystallize to single crystals in suitable situations and their structures can be determined by single crystal X-ray diffraction.In this thesis,we discuss main about the synthesis methods and structures of thiolated Ag and alkynyl protected Au/Ag nanoclusters.Some properties of the noble metal nanoclusters were investigated as well.The main findings of the thesis are shown in the below:1.Developing a combinatorial indentification of hydrides in Ag hydride nanoclusters:a 40-atom Ag hydride nanocluster,[Ag40(SR)24(PPh3)8H12]2+,is successfully synthesed as follows:use Ag2CO3 as the precursor and 2,4-dimethylthiophenol and triphenolphosphine as protected ligands,in the two-phase condition,later reduced by the NaBH4.The Ag40H12 cluster is a two electron superatomic system with a simple cub as its innermost core,through the combination of mutiple experimental techniques,the positions of 12 hydrides are indentified.Moreover,based on the DFT calculations and experimental probes,it was demonstrated that the 12 hydrides play a crucial role in stabilizing both the electronic and geometric structure of the Ag40H12 cluster.2.Transfer chemistry of thiolated Ag hydride nanocluster:in the synthesis method of Ag40H12 cluster,we replaced the 2,4-dimethylthiophenol to 1-Adamantane mercaptan and obtained another Ag hydride nanocluster:[Ag29(SR)18(PPh3)4H8]+.The core of Ag29H8 cluster is a cuboctahedron with four hydrides in the core and four hydrides outside it.The surface hydrides enables the reactivity of the Ag29H8 cluster.With further reacting with PdCl2 and PA,we got a new cluster:[Ag28Pd(SR)12(PA)6(PPh3)4]2+,with a core shift from cuboctahedron to icosahedron and without hydrides.3.High-nuclear Au/Ag nanoclusters protected by phenylacetylene:Based on the traditional synthesis method of(AuAg)144(PA)48Cl8.PPh4Br was added to provide Br-,a new cluster:[Au74Ag60Br12(PA)40](PPh4)2 was obtained.The yield of(AuAg)134 is 70%,which is the highest yield in the alkynyl protected nanocluster systems.The structures of these two clusters are similiar,while the Br atoms capped on the two poles of the(AuAg)134 cluster,their surface structures are different.We also modified the synthesis method to obtain greater yield and did the DPV tests of these two clusters,which are so different between these two clusters.