Ruthenium chemical properties

Because of the enormous synthetic potential of molybdenum- [22] and ruthenium-based [57,806] single-component catalysts, a closer look at the scope and limitations of the most promising compounds known to date is appropriate. The systematic exploration of the synthetic possibilities offered by these new catalysts has just begun, and many new developments are to be expected in the near future [744,746,747,807]. As quick reference for the organic chemist, the most relevant chemical properties of two types of frequently used catalyst (Figure 3.46) are listed below. These carbene complexes are quite robust and well-suited to the metathesis of elaborate organic intermediates. 

Platinum metah—includes unreactive transition elements located in groups 8, 9, and 10 of periods 5 and 6. They have similar chemical properties. They are ruthenium, rhodium, palladium, osmium, iridium, and platinum. 

Platinum is the main metal in the platinum group, which consists of metals in both period 5 and period 6. They are ruthenium (Ru), rhodium (Ro), and palladium (Pd) in period 5 and osmium (Os), iridium (Ir), and platinum (Pt) in period 6. All six of these metals share some of the same physical and chemical properties. Also, the other metals in the group are usually found in platinum ore deposits. 

Highly reactive organic vinylidene and allenylidene species can be stabilized upon coordination to a metal center [1]. In 1979, Bruce et al. [2] reported the first ruthenium vinylidene complex from phenylacetylene and [RuCpCl(PPh3)2] in the presence of NH4PF6. Following this report, various mthenium vinylidene complexes have been isolated and their physical and chemical properties have been extensively elucidated [3]. As the a-carbon of ruthenium vinylidenes and the a and y-carbon of ruthenium allenylidenes are electrophilic in nature [4], the direct formation of ruthenium vinylidene and ruthenium allenylidene species, respectively, from terminal alkynes and propargylic alcohols provides easy access to numerous catalytic reactions since nucleophilic addition at these carbons is a viable route for new catalysis (Scheme 6.1). 

Physico-Chemical Properties of Novel Nanocrystalline Ruthenium Based Chalcogenide Materials... 

Stabilization of organic vinylidene and allenylidene species via coordination to a ruthenium centre is now well established, and the stoichiometric reactivity of these highly unsaturated ligands is still under intense investigation [ 1-4], and theoretical studies are being carried out [5,6]. Most of the chemical properties of cumulenylidene structures arise from the alternate electronic distribution along the carbon chain (Fig. 1). 

Osmium bears a close resemblance to ruthenium in many of its chemical properties in fact, in certain respects, such as the formation of tetroxides, these two elements are absolutely unique amongst the metals of the platinum group. 

In its chemical properties, the oxyfluoride behaves as a derivative of five-positive platinum. Potassium hexafluoroplatinatc(v) (Found F, 32-0. KPtF, requires F, 32-7%) is formed when the oxyfluoride vapour is passed over hot potassium fluoride and when potassium fluoride is mixed with the oxy-fluoridc in iodine pentafluoride solution. Potassium hexafluoroplatinatc(v) has a rhombohedral unit cell with a = 4-97 A, a = 97-5°, and is isomorphous with its ruthenium, osmium, and iridium analogues. Dissolution of the oxyfluoride in chlorine trifluoride and in iodine p>entafluoride yields 1 1 platinum penta-fluoridc-solvent adducts. 

Osmium is an element in Group 8 (VIIIB) of the periodic table. The periodic table is a chart showing how chemical elements are related to one another. Osmium is also a member of the platinum family. This family consists of five other elements ruthenium, rhodium, palladium, iridium, and platinum. These elements often occur together in Earth s cmst. They also have similar physical and chemical properties, and they are used in alloys. 

Kleijn, J.M., and Lyklema, J., Colloid-chemical properties of ruthenium dioxide in relation to catalysis of the photochemical generation of hydrogen, Colloid Polym. Sc/., 265, 1105. 1987. 

In the present work, we investigated the influence of the metal precursor and of the nature of the support on the performences of ruthenium catalysts for the wet air oxidation of p-hydroxybenzoic (p-HBZ) acid chosen as a model of phenolic pollutants. Titanium and zirconium oxides were selected as supporting materials. The preparation method adopted for supports was sol-gel combined with the use of supercritical drying. The motivation of such combination is to prepare aerogel supports with high BET surface area and unique morphological and chemical properties [9,10]. 

It seems that one of the future developments in cluster chemistry lies in the production of nanosized particles (1 nm = 10 A) with well defined stoichiometries, which can be used as catalysts or as catalyst precursors. In this context, high nuclearity mixed-metal clusters are particularly useful because two or more metal atoms with different chemical properties can be combined in the same unit. The Cambridge group has spent the last few years designing rational synthetic routes to mixed-metal high nuclearity clusters of ruthenium and osmium with the coinage elements, which produce cluster cores of up to one nanometer in size. ... 

Ruthenium(VI) oxide tetrafluoride, [RUOF4], is reported to have been prepared by the action of a mixture of BrFj and Br2 on ruthenium. The enthalpy and entropy of vaporization. X-ray powder pattern and magnetic properties (jt = 2.91 BM at room temperature) have been measured. However more recently other workers also claim to have prepared [RUOF4] (by the fluorination of RuOj at 400-500°C), but it shows different properties to the earlier product. Evidence for its formulation is based on mass spectroscopy (which shows the molecular ion [RUOF4 ] ), elemental analysis and IR spectrum (v(Ru=0)= 1040cm ). The solid is unstable, even at room temperature, decomposing to [RUF4] and A report on the physical and chemical properties of... 

The lanthanide contraction, however, has also effects for the rest of the transition metals in the lower part of the periodic system. The lanthanide contraction is of sufficient magnitude to cause the elements which follow in the third transition series to have sizes very similar to those of the second row of transition elements. Due to this, for instance hafnium (Hf ) has a 4" -ionic radius similar to that of zirconium, leading to similar behavior of these elements. Likewise, the elements Nb and Ta and the elements Mo and W have nearly identical sizes. Ruthenium, rhodium and palladium have similar sizes to osmium iridium and platinum. They also have similar chemical properties and they are difficult to separate. The effect of the lanthanide contraction is noticeable up to platinum (Z = 78), after which it no longer noticeable due to the so-called Inert Pair Effect (Encyclopedia Britannica 2015). The inert pair effect describes the preference of post-transition metals to form ions whose oxidation state is 2 less than the group valence. 

Hassium, element 108, does not exist in nature but must be made in a particle accelerator. It was first created in 1984 and can be made by shooting mag-nesium-26 (ifMg) atoms at curium-248 ( HCm) atoms. The collisions between these atoms produce some hassium-265 (io Hs) atoms. The position of hassium in the periodic table (see Fig. 2.20) in the vertical column containing iron, ruthenium, and osmium suggests that hassium should have chemical properties similar to these metals. However, it is not easy to test this prediction—only a few atoms of hassium can be made at a given time and they last for only about 9 seconds. Imagine having to get your next lab experiment done in 9 seconds ... 

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