Platinum group elements ruthenium

Capobianco, C.H. Drake, M. 1990. Partitioning of ruthenium, rhodium, and palladium between spinel and silicate melt and implications for platinum-group element fractionation trends, Geochimica et Cosmochimica Acta, 54, 869-874. 

Ruthenium was the last of the platinum-group elements to be discovered, and has perhaps the most interesting and challenging chemistry of the six. In this book just one major aspect is covered its ability, mainly by virtue of its remarkably wide range of oxidation states which exist in its many complexes (from +8 to -2 inclusive) to effect useful and efficient oxidations of organic substrates. 

Distributions of the platinum group elements (PGEs) are shown in Fig. 12.8. The distribution of ruthenium (Ru) is unknown, but concentrations are estimated to be less than 50 fmol kg-1. The distributions of rhodium (Rh) and palladium (Pd) (Period 5) show significant surface depletions relative to deep waters and overall concentrations are somewhat less than 1 pmol kg 1. 

Some of the elements can be found in their native state because they are largely unreactive. Unfortunately, this list is short of metals that exist in their native state in large amounts it includes gold, silver, and copper (the Group 11 elements) and the platinum group metals (ruthenium, rhodium, palladium, osmium, iridium, and platinum). 

The electrochemical deposition of a metallic-ruthenium film is very difficult compared with that of other platinum-group elements [46, 61, 91-93]. One of the reasons may be related to the comphcated electrochemistry of ruthenium deposition and the stability of the Ru-chloro complex [92]. For example, it has been reported that the RuCfi species in HCIO4 solution is decomposed partly into RuO +, in which Ru(IV) is present [94]. 

Discovery Priority for a sixth platinum group element was claimed in 1809 by the Pole Sniadecki and in 1828 by Osann from Estonia. None of these discoveries was approved. In 1844 Karl Karlovich Klaus, Estonia, discovered a new metal in Russian platinum and named the new element ruthenium after Russia. 

Ruthenium and osmium are generally found in the metallic state along with the other platinum metals and the coinage metals. The major source of the platinum metals are the nickel-copper sulfide ores found in South Africa and Sudbury (Canada), and in the river sands of the Urals in Russia. They are rare elements, ruthenium particularly so, their estimated abundances in the earth s crustal rocks being but O.OOOl (Ru) and 0.005 (Os) ppm. However, as in Group 7, there is a marked contrast between the abundances of the two heavier elements and that of the first. 

The most widely used method for adding the elements of hydrogen to carbon-carbon double bonds is catalytic hydrogenation. Except for very sterically hindered alkenes, this reaction usually proceeds rapidly and cleanly. The most common catalysts are various forms of transition metals, particularly platinum, palladium, rhodium, ruthenium, and nickel. Both the metals as finely dispersed solids or adsorbed on inert supports such as carbon or alumina (heterogeneous catalysts) and certain soluble complexes of these metals (homogeneous catalysts) exhibit catalytic activity. Depending upon conditions and catalyst, other functional groups are also subject to reduction under these conditions. 

Numerous studies aimed at the understanding of the mechanism of these processes rapidly appeared. In this context, Murai examined the behavior of acyclic linear dienyne systems in order to trap any carbenoid intermediate by a pendant olefin (Scheme 82).302 A remarkable tetracyclic assembly took place and gave the unprecedented tetracyclo[6.4.0.0]-undecane derivatives as single diastereomer, such as 321 in Scheme 82. This transformation proved to be relatively general as shown by the variation of the starting materials. The reaction can be catalyzed by different organometallic complexes of the group 8-10 elements (ruthenium, rhodium, iridium, and platinum). Formally, this reaction involves two cyclopropanations as if both carbon atoms of the alkyne moiety have acted as carbenes, which results in the formation of four carbon-carbon bonds. 

Ruthenium also belongs to the platinum group, which includes six elements with similar chemical characteristics. They are located in the middle of the second and third series of the transition elements (groups 8, 9, and 10). The platinum group consists of ruthenium, rhodium, palladium, osmium, iridium, and platinum. 

The platinum-group metals (PGMs), which consist of six elements in Groups 8— 10 (VIII) of the Periodic Table, are often found collectively in nature. They are ruthenium, Ru rhodium, Rh and palladium, Pd, atomic numbers 44 to 46, and osmium, Os iridium, Ir and platinum, Pt, atomic numbers 76 to 78. Corresponding members of each triad have similar properties, eg, palladium and platinum are both ductile metals and form active catalysts. Rhodium and iridium are both characterized by resistance to oxidation and chemical attack (see Platinum-group metals, compounds). 

Os forms many complexes with nitnte. oxalate, carbon monoxide, amines, and thio ureas. The latter arc important analytically Osmium forms the interesting aromatic sandwich" compound, osmocene. A metallocene is described under Ruthenium. See also Chemical Elements and Platinum and Platinum Group. 

Electronic configuration 1. v22522/763 23/7 3 l04 24/764 /5.s 1. Ionic rad ius Ru4+ 0,60 A. Metallic radius 1,3251 A. First ionization potential 7.5 eV. Other physical properties of ruthenium will be found under Platinum and Platinum Group. See also Chemical Elements,... 

As its title implies, this review restricts itself to describing and discussing compounds of platinum group metals—i.e., of ruthenium, rhodium, palladium, osmium, iridium, and platinum—although the compounds of the other transition elements and even some post-transition elements are either fully analogous or closely related to those of the platinum metals. 

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. 

The platinum-group metals consist of ruthenium, rhodium, palladium, osmium, iridium, and platinum. Each of the metals occurs naturally in its native form, and in economically exploitable deposits the elements occur overwhelmingly as individual platinum-group mineral (PGM) species. Mutual substitution of the various PGE is common, but substitutions in other minerals, such as base-metal sulfides, typically occur to only a limited extent. A comprehensive review of PGM and PGE geochemistry is given by Cabri (2002). 

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. 

Palladium is found in Row 5, Group 10 (VIIIB) of the periodic table. The periodic table is a chart that shows how chemical elements are related to each other. Palladium, ruthenium, rhodiiun, osmium, iridium, and platinum make up the platinum group of metals. These metals are also sometimes called the noble metals. That term reflects the fact that the six elements are not very reactive. The elements in row 5 of the periodic table typically have one or more electrons in the fifth orbital. Palladium is an exception, which is the reason that no electrons are shown in the element s outermost orbital, as shown in the diagram at the top of this page. 

Special attention is due to the centerpiece in chemo-catalysis the metal. As can be seen in previously shown examples this vital component is represented by members from the group of transition or main-group elements. Notable examples are rhodium (Rh), ruthenium (Ru), palladium (Pd), platinum (Pt), cobalt (Co), chromium (Cr), iridium (Ir), vanadium (V), titanium (Ti), and tungsten (W) but less precious ones such as iron (Fe), molybdenum (Mo), copper (Cu), and zinc (Zn) are also quite prevalent. 

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