Transition-metal clusters structure

Transition-metal carbonyls, 16 58 Transition metal catalysts, 20 151-152 Transition-metal-catalyzed microwave-assisted reactions, 16 552 Transition metal-catalyzed reactions in ionic liquids, 26 878-897 Transition-metal clusters, structure of,... 

Concelcao J, Laaksonen R T, Wang L S, Guo T, Nordlander P and Smalley R E 1995 Photoelectron spectroscopy of transition metal clusters correlation of valence electronic structure to reactivity Rhys. Rev. B 51 4668... 

Wang L S and Wu H 1998 Probing the electronic structure of transition metal clusters from molecular to bulk-like using photoeieotron spectroscopy Cluster Materials, Advances In Metal and Semiconductor Clusters vo 4, ed M A Duncan (Greenwich JAI Press) p 299... 

Pastor G M, Dorantes-Davila J and Bennemann K H 1989 Size and structural dependence of the magnetic properties of small 3d-transition metal clusters Phys. Rev. B 40 7642... 

Electronic structures of transition metal cluster complexes. M. C. Manning and W. C. Trogler, Coord. Chem. Rev., 1981, 38, 89-138 (406). 

The electronic structure of transition metal cluster complexes with weak- and strong-field ligands. G. P. Kostikova and D. V. Korol kov, Russ. Chem. Rev. (Engl. Transl.), 1985,54, 344 (137). 

Pauling, L. Structure of Transition-Metal Cluster Compounds Use of an Additional Orbital Resulting from the f,g Character of spd Bond Orbitals Proc. Natl. Acad. Sci. (USA) 1977, 74, 5235-5238. 

Ames Laboratory (Iowa State University, USA) investigating new solid state phases based on reduced rare earth halides. Since 1993, she has held a position at the University Jaume 1 of Castello (Spain) and became Associate Professor of Physical Chemistry in 1995. During the second semester of 2005, she held a visiting professor position at the Laboratory of Chemistry, Molecular Engineering and Materials of the CNRS-Universtity of Angers (France). Her research has been focussed on the chemistry of transition metal clusters with special interest in multifunctional molecular materials and the relationship between the molecular and electronic structures of these systems with their properties. She is currently coauthor of around 80 research papers on this and related topics. 

Although there are a lot of publications on the chemistry of technetium [2-4] and transition-metal clusters [1,5-8], the chemistry of technetium clusters was insufficiently studied until the early eighties [1,2]. Nevertheless, the available scanty data on the compounds with Tc-Tc bonds inspired hope that interesting results would be obtained in the chemistry of technetium in general, in radiochemistry, and in the chemistry of transition-metal cluster compounds. The anticipated results were actually obtained [9-15] and the conclusion was drawn that technetium had a number of anomalous cluster-forming properties [9]. This review looks at the detailed studies of these properties and their interpretation in terms of electronic structure theory. 

The information available is discussed in light of the effects of excitation energy and the environment on the photofragmentation process of several transition metal cluster complexes. The photochemical information provides a data base directly relevant to electronic structure theories currently used to understand and predict properties of transition metal complexes (1,18,19). 

Amino acid is one of the most important biological ligands. Researches on the coordination of metal-amino acid complexes will help us better understand the complicated behavior of the active site in a metal enzyme. Up to now many Ln-amino acid complexes [50] and 1 1 or 1 2 transition metal-amino acid complexes [51] with the structural motifs of mononuclear entity or chain have been synthesized. Recently, a series of polynuclear lanthanide clusters with amino acid as a ligand were reported (most of them display a Ln404-cubane structural motif) [52]. It is also well known that amino acids are useful ligands for the construction of polynuclear copper clusters [53-56], Several studies on polynuclear transition metal clusters with amino acids as ligands, such as [C03] [57,58], [Co2Pt2] [59], [Zn6] [60], and [Fe ] [61] were also reported. 

Size and Structural Dependence of the Magnetic Properties of 3d Transition Metal Clusters. 

Heating peralkylated derivatives 56a in BBr3 leads selectively to the 6-bromo derivatives 56b via Br/alkyl exchange [74], Among other transformations, the reaction of 56b with the sodium salt of a thioazadiiron cluster is an example of combining main group and transition metal clusters in one molecule (56c), which provided crystals for structural characterization (Scheme 3.2-29) [75]. 

The efforts to rationalize the formulas and structures of Zintl ions and related species predated extensive definitive structural information on anionic post-transition metal clusters obtained by Corbett and his group in the 1970s [8, 9]. After enough such structural information on the bare post-transition metal clusters became available, the resemblance of their polyhedra to the known polyhedral boranes became apparent. For this reason, the simple Zintl-Klemm concept has been largely superseded by newer, more advanced descriptions of chemical bonding in such clusters, initially those applied to the polyhedral boranes. 

In practice, however, already with a comparatively small number of metal atoms it is no longer feasible to investigate all possible spin states with all potential realizations by various local spin distributions. Assumptions on the interaction of the metal centers on the basis of their structural arrangement and experimental susceptibility measurements have to be made. For example, for the BS state of a tetranuclear transition-metal cluster, one has to decide which of the four metal atoms couple in an antiferromagnetic fashion with each other. Prominent coupling schemes are, e.g., the dimer-of-dimers 2-plus-2-type or the 3-plus-... 

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