Transition Metal-based Molecules

Inorganic systems featuring linkage isomerism induced by changing the oxidation state of a metal are also known.145-561 For instance, a sulfoxide is O-bonded to ruthenium n) in its stable form (Ru-OSR2). On reduction of the metal to the divalent state, the initially obtained O-bonded species rearranges to afford the stable S- 

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Since the first reports on Wilkinson s catalyst,19,20 many transition-metal-based catalytic systems for hydrogenation of unsaturated organic molecules have been developed. Two major pathways seem to occur, one involving monohydride (M—11) species, and the other, dihydride (MH2)... 

On these transition metal-based catalysts, the selechve hydrogenahon of the C=0 group is very difficult because C=C double bond hydrogenahon is both thermodynamically and kinehcally favored, especially in the case of small molecules (e.g., acrolein, crotonaldehyde) where addihonal steric effects are not important [62, 71, 72]. 

Sponsored by the European Community, a Ct chemistry course was organized at Aachen by Prof. Keim. Dr Bchr and Dr Roper of the Technical University of Aachen, Prof, Teyssie and Prof. Hubert of the University of Liege and Prof. L go of the University of. Milan. The three-day course devoted to the application of predominantly liom( cneous transition metal based catalysis in C molecules formed the skeleton for this botrk. In nine chapters the following topics are covered the reduction of CO and reactions with CO. the chemistry of methanol, activation of carbon dioxide, hydrocyanation. methane chemistry and carbene chemistry. 

Cahill, P.A. Nonlinear optical waveguides containing a transition metal-based dye molecule. Mater. Res. Soc. Symp. Proc. 109, 319-322 (1988)... 

Methane CPO has been intensively studied to select new advanced catalysts able to maximize hydrocarbon conversion, hydrogen yield and especially to control catalytic deactivation phenomena, strictly connected to coke deposition problem, similar to SR process [18-23]. The role of transition metal-based catalysts in methane CPO reaction mechanism has been detailed [24], evidencing that fuel dissociation step is crucial for a viable overall process rate at reasonable temperatures, as expected taking into account the stability of methane molecule. 

The modulation of the photophysical properties of Ru(II) polypyridyl complexes through interaction with the various biologically relevant molecules mentioned in the previous sections (pH, O2, anions, cations, and DNA) has culminated in their use at the forefront of transition-metal-based intracellular imagine agents. Although there are many good examples that utilize the Ru(ll) lumophores, many of which were reviewed by Coogan and coworkers, only a few select examples are discussed in order... 

Almost a decade ago the first molecular superconductors based on the transition metal complex molecule (TTF)[Ni(dmit)2]2 was discovered (TTF = tetrathiafiilvalene, dmit = isotrithionedithiolate) [ 1 ]. Since then several M(dmit)2 superconductors have been found. Although most of the molecular metals currently studied are systems based on multi-sulfur (or selenium) 71 molecules, the first example of a metallic molecular crystal was a partially oxidized platinum complex. The discovery of the partially oxidized platinum complex is very old, about 150 years ago, but the physical meaning of the system had not been noticed until the crystal structure (by Krogmann and Hausen) revealed the existence of the extended linear Pt-Pt metal bonds [2]. The diffuse X-ray scattering experiments on this system (K2[Pt(CN)4]Bro.3 3H2O) by Comes et al. [3] convinced many people, who were interested in conducting crystalline molecular solids at that time, of the existence of one-dimensional metal electrons in molecular crystals for the first time, and so a new era of metallic molecular systems had been bom. 

In the previous section, a brief history of the development of molecular metals composed of transition metal complex molecules was mentioned fi om the viewpoint of molecular design. As will be described in Section 4, various new types of molecular conductors based on transition metal complexes have begun to appear but this new evolution seems to be still at an early stage. The molecular conductors sufficiently studied are the systems composed of M(dmit)2 molecules, from which seven superconductors have been discovered. In this chapter, the general feature of the simple band electronic structures of n molecular conductors based on M(dmit)2 (M = Ni, Pd, Pt) will be described. 

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