NEW NANOSIZED TRANSITION METAL CLUSTERS, SYNTHESIS, STRUCTURES, AND PHOTOPHYSICAL PROPERTIES
D. Fenske, Paloma Sevillano, T. Langetepe, N. Zhu
There are a number of metal chalcogenide ions known in the gas phase. Examples are [Cu2n+1En]- (E: S, Se), [Ag2n+1Sn]- and [NixSy]- clusters. Obviously it is possible to stabilize these species with protecting PR3 ligands. Ab initio calculations show that the influence of the tertiary PR3 ligands depends on the cluster size and type of the PR3 ligand used. An easy route to such compounds is via the reaction of transition metal halides with silylated derivatives of S and Se. Examples are [Cu12Se6(Pr3)8], [Cu20Se10(PR3)8], [Cu26Se13(PR3)14], [Cu30Se15(PR3)12], [Cu44Se22(PR3)12], [Cu48Se22(PR3)20], [Cu59Se30(PR3)15], [Ag112Se32(SeBu)48(PBu3)12], [Ag172Se40(SeBu)92(dppp)4] and many other clusters. During the last time we were also able to synthesize Au Clusters with up to 90 Au atoms. Examples are ionic clusters like: [Au10Se4(dppe)4Br2], [Au18Se8(dppe)6Br2], [Au34Se14(tpep)6(tpepSe)2Cl6]. These compounds show interesting photophysical properties. These materials may be regarded as sections cut out of the structure of binary phases which are effectively shielded by an envelope of PR3 ligands. The structures, properties and results from ab initio calculations will be reported. The conductivity is strongly dependent on the cluster size. Under high vacuum conditions the PR3 ligands can be removed from the cluster surface. This results in the formation of an amorphous nano composite material. The size of the particles is between 3.0 to 5.0 nm with a very narrow size.