Clusters trimeric

For methanol clusters [36], it was found that the dimer is linear, while clusters of 3 and 4 molecules exist as monocyclic ring structures. There also is evidence that there are two cyclic ring trimer confomiers in the molecular beam. 

The trimetaUic uranyl cluster (U02)3(C03) 3 has been the subject of a good deal of study, including nmr spectroscopy (179—182) solution x-ray diffraction (182), potentiometric titration (177,183,184), single crystal x-ray diffraction (180), and exafs spectroscopy in both the soHd and solution states (180). The data in this area have consistendy led to the proposal and verification of a trimeric (U02)3(C03) 3 cluster (181,182,185). 

At normal temperatures, sulfur trioxide is a volatile liquid (its boiling point is 45°C), composed of trigonal planar S03 molecules. In the solid and to some extent in the liquid, these molecules form trimers (unions of three molecules) of composition S309 (14) as well as larger clusters. 

These methods may be used to prepare mixed metal clusters. Simultaneous codeposition of Ag and Cu vapors in Ar at 10-12 K yields a mixture including atomic Ag and Cu, dimers Ag, and Cu, together with AgCu. At 77 K, CuAg4 and Cu,Ag3 clusters occur . The amount of AgCu can be increased by photoexcitation with 305 nm Ag or Cu atomic radiation. The trimer AuAgCu is produced when a mixture of Au, Ag and Cu vapors is condensed at 77 K. 

Section II describes recent improvements in methodology that have significantly improved the accuracy of calculations on small metal clusters. Section III describes the calculation of some accurate dimer and trimer potentials, and the insight they give into the nature of metal chemistry. Section IV reviews the work on small metal clusters and discusses how the ab initio and parameterized model approaches are interfaced. Section V contains our conclusions. 

Structure on the (ab) plane (dark octahedra (NbeClgOl jCle clusters, light Ti3Cl706 trimers, centered Ti2Cl9 dimers, large... 

Nielsen, I. M. B., Seidl, E., Janssen, C. L., 1999, Accurate Structures and Binding Energies for Small Water Clusters The Water Trimer , J. Chem. Phys., 110, 9435. 

The N,S-chelate 2-aminoethanethiolate (aet-) forms stable cobalt(III) complexes, including clusters where the S can take on a bridging role. Reaction of [Co(NH3)5C1]2+ with Ni(aet)2 in water for several hours affords the black tetranuclear compound Co4(aet)8, which features act in simple chelate and bridging roles (245).1083 The simple monomeric complex [Co(aet)2(en)]+ has been reported 1084 when heated in water at 50 °C, the trimer Co Co(aet)3 2 is one product, with the central Co surrounded by six bridging S atoms. 

Figure 1.5 (a) Hierarchy of clusters of rubrene on Au l 1 1, showing the evolution from trimers to pentamers of trimers and eventually 150 molecules per cluster as a decamer of the pentamers. (b) Illustration ofthe preservation of chirality through the hierarchy. (Adapted with permission from Ref. [9]). 

Cobalt shows a dramatic size dependence(JJ cJ that resembles the behavior of iron more so than that of vanadium or niobium. The smallest cluster to react is the trimer and the 5-9 atom clusters are significantly more inert than any of the larger clusters. Cobalt also has a significant dip in reactivity between 19 and 22. A theoretical calculation rationalized the onset in reactivity at the trimer to be associated with energetic stability of the products(29). 

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