The Experts below are selected from a list of 61443 Experts worldwide ranked by ideXlab platform
Sergey Vl. Kryutchkov - One of the best experts on this subject based on the ideXlab platform.
-
Physicochemical properties of Technetium acido clusters
Russian Chemical Reviews, 1998Co-Authors: Sergey Vl. KryutchkovAbstract:The review is concerned with the electronic and molecular structure and physicochemical properties of all types of Technetium clusters with acido ligands described to date. As a typical cluster-forming metal, Technetium possesses a number of specific, anomalous cluster-forming properties that can be interpreted in terms of greater capability of outer diffuse 5s(5p) AOs to participate in the formation of additional M–M bonds in Technetium acido clusters as compared to analogous clusters of other transition d-elements. Theoretical interpretation of the electronic and molecular structure and properties of Technetium clusters has been confirmed by experimental data (X-ray analysis, magnetochemistry, and EPR, optical, X-ray photoelectron and X-ray emission spectroscopy). The experimentally observed increased stability of Technetium clusters with odd numbers of 'metallic' electrons and a decrease in the effective charge on Tc atoms upon formation of the M–M bonds are discussed. Recently found 'anomalous' properties of Technetium and rhenium compounds with ferrocenium cations (in particular, unusual low-temperature electron emission on X-ray irradiation) are also considered. The bibliography includes 101 references
-
Chemistry of Technetium cluster compounds
Topics in Current Chemistry, 1996Co-Authors: Sergey Vl. KryutchkovAbstract:This review is concerned with the syntheses, electronic and molecular structures, and properties of all types of presently known Technetium cluster compounds with acido-ligands. Examination of the literature shows that Technetium is not only a typical cluster-forming agent, but also has a number of specific “anomalous” cluster-forming properties. These properties may be interpreted in terms of a greater ability of the outer diffuse 5s(5p)-AO's to participate in additional M-M bonding in Technetium acido-clusters, compared to the situation in analogous clusters of other d-transition elements. Theoretical interpretations of the electronic and molecular structures and properties of Technetium clusters are supported by experimental data (X-ray diffraction analysis, magnetochemistry, and optical, ESR, X-ray emission, and X-ray photoelectron spectroscopies). The observed increased stability of Technetium clusters with an odd number of “metallic” electrons and a decrease in the effective charge on Technetium atoms upon formation of M-M bonds are discussed.
Kenneth R Czerwinski - One of the best experts on this subject based on the ideXlab platform.
-
Recent advances in Technetium halide chemistry.
Accounts of chemical research, 2014Co-Authors: Frederic Poineau, Kenneth R Czerwinski, Erik V. Johnstone, Alfred P SattelbergerAbstract:Transition metal binary halides are fundamental compounds, and the study of their structure, bonding, and other properties gives chemists a better understanding of physicochemical trends across the periodic table. One transition metal whose halide chemistry is underdeveloped is Technetium, the lightest radioelement. For half a century, the halide chemistry of Technetium has been defined by three compounds: TcF6, TcF5, and TcCl4. The absence of Tc binary bromides and iodides in the literature was surprising considering the existence of such compounds for all of the elements surrounding Technetium. The common synthetic routes that scientists use to obtain binary halides of the neighboring elements, such as sealed tube reactions between elements and flowing gas reactions between a molecular complex and HX gas (X = Cl, Br, or I), had not been reported for Technetium. In this Account, we discuss how we used these routes to revisit the halide chemistry of Technetium. We report seven new phases: TcBr4, TcBr3, α/...
-
Technetium chemistry in the fuel cycle combining basic and applied studies
Inorganic Chemistry, 2013Co-Authors: Frederic Poineau, Edward Mausolf, Gordon D Jarvinen, Alfred P Sattelberger, Kenneth R CzerwinskiAbstract:Technetium is intimately linked with nuclear reactions. The ultraminute natural levels in the environment are due to the spontaneous fission of uranium isotopes. The discovery of Technetium was born from accelerator reactions, and its use and presence in the modern world are directly due to nuclear reactors. While occupying a central location in the periodic table, the chemistry of Technetium is poorly explored, especially when compared to its neighboring elements, i.e., molybdenum, ruthenium, and rhenium. This state of affairs, which is tied to the small number of laboratories equipped to work with the long-lived 99Tc isotope, provides a remarkable opportunity to combine basic studies with applications for the nuclear fuel cycle. An example is given through examination of the Technetium halide compounds. Binary metal halides represent some of the most fundamental of inorganic compounds. The synthesis of new Technetium halides demonstrates trends with structure, coordination number, and speciation that ca...
Alfred P Sattelberger - One of the best experts on this subject based on the ideXlab platform.
-
Recent advances in Technetium halide chemistry.
Accounts of chemical research, 2014Co-Authors: Frederic Poineau, Kenneth R Czerwinski, Erik V. Johnstone, Alfred P SattelbergerAbstract:Transition metal binary halides are fundamental compounds, and the study of their structure, bonding, and other properties gives chemists a better understanding of physicochemical trends across the periodic table. One transition metal whose halide chemistry is underdeveloped is Technetium, the lightest radioelement. For half a century, the halide chemistry of Technetium has been defined by three compounds: TcF6, TcF5, and TcCl4. The absence of Tc binary bromides and iodides in the literature was surprising considering the existence of such compounds for all of the elements surrounding Technetium. The common synthetic routes that scientists use to obtain binary halides of the neighboring elements, such as sealed tube reactions between elements and flowing gas reactions between a molecular complex and HX gas (X = Cl, Br, or I), had not been reported for Technetium. In this Account, we discuss how we used these routes to revisit the halide chemistry of Technetium. We report seven new phases: TcBr4, TcBr3, α/...
-
Technetium chemistry in the fuel cycle combining basic and applied studies
Inorganic Chemistry, 2013Co-Authors: Frederic Poineau, Edward Mausolf, Gordon D Jarvinen, Alfred P Sattelberger, Kenneth R CzerwinskiAbstract:Technetium is intimately linked with nuclear reactions. The ultraminute natural levels in the environment are due to the spontaneous fission of uranium isotopes. The discovery of Technetium was born from accelerator reactions, and its use and presence in the modern world are directly due to nuclear reactors. While occupying a central location in the periodic table, the chemistry of Technetium is poorly explored, especially when compared to its neighboring elements, i.e., molybdenum, ruthenium, and rhenium. This state of affairs, which is tied to the small number of laboratories equipped to work with the long-lived 99Tc isotope, provides a remarkable opportunity to combine basic studies with applications for the nuclear fuel cycle. An example is given through examination of the Technetium halide compounds. Binary metal halides represent some of the most fundamental of inorganic compounds. The synthesis of new Technetium halides demonstrates trends with structure, coordination number, and speciation that ca...
Frederic Poineau - One of the best experts on this subject based on the ideXlab platform.
-
Recent advances in Technetium halide chemistry.
Accounts of chemical research, 2014Co-Authors: Frederic Poineau, Kenneth R Czerwinski, Erik V. Johnstone, Alfred P SattelbergerAbstract:Transition metal binary halides are fundamental compounds, and the study of their structure, bonding, and other properties gives chemists a better understanding of physicochemical trends across the periodic table. One transition metal whose halide chemistry is underdeveloped is Technetium, the lightest radioelement. For half a century, the halide chemistry of Technetium has been defined by three compounds: TcF6, TcF5, and TcCl4. The absence of Tc binary bromides and iodides in the literature was surprising considering the existence of such compounds for all of the elements surrounding Technetium. The common synthetic routes that scientists use to obtain binary halides of the neighboring elements, such as sealed tube reactions between elements and flowing gas reactions between a molecular complex and HX gas (X = Cl, Br, or I), had not been reported for Technetium. In this Account, we discuss how we used these routes to revisit the halide chemistry of Technetium. We report seven new phases: TcBr4, TcBr3, α/...
-
Technetium chemistry in the fuel cycle combining basic and applied studies
Inorganic Chemistry, 2013Co-Authors: Frederic Poineau, Edward Mausolf, Gordon D Jarvinen, Alfred P Sattelberger, Kenneth R CzerwinskiAbstract:Technetium is intimately linked with nuclear reactions. The ultraminute natural levels in the environment are due to the spontaneous fission of uranium isotopes. The discovery of Technetium was born from accelerator reactions, and its use and presence in the modern world are directly due to nuclear reactors. While occupying a central location in the periodic table, the chemistry of Technetium is poorly explored, especially when compared to its neighboring elements, i.e., molybdenum, ruthenium, and rhenium. This state of affairs, which is tied to the small number of laboratories equipped to work with the long-lived 99Tc isotope, provides a remarkable opportunity to combine basic studies with applications for the nuclear fuel cycle. An example is given through examination of the Technetium halide compounds. Binary metal halides represent some of the most fundamental of inorganic compounds. The synthesis of new Technetium halides demonstrates trends with structure, coordination number, and speciation that ca...
Kazuo Minato - One of the best experts on this subject based on the ideXlab platform.
-
Heat capacities of Technetium metal and Technetium–ruthenium alloy
Journal of Alloys and Compounds, 2002Co-Authors: Yoshiro Shirasu, Kazuo MinatoAbstract:Abstract The transmutation of Technetium-99 to stable nuclides of ruthenium by neutron irradiation is an attractive option to reduce the long-term risk of the storage of high-level waste from nuclear reactors. In order to estimate the property and the behavior of Technetium metal target for transmutation, disk-shaped samples of Technetium metal and Technetium–ruthenium alloy were prepared and characterized. The heat capacities of Tc 0.51 Ru 0.49 alloy as well as Tc and Ru metals were measured by a differential scanning calorimeter from room temperature to about 1100 K. The measured heat capacity of Tc metal is larger than that of Ru metal. The measured heat capacity of Tc 0.51 Ru 0.49 alloy agrees very well with the calculated one from the measured heat capacities of Tc and Ru metals using the Neumann–Kopp rule.
-
Thermal conductivity of Technetium
Journal of Alloys and Compounds, 1998Co-Authors: Kazuo Minato, Hiroyuki Serizawa, Kousaku FukudaAbstract:The thermal diffusivity of Technetium was measured on a disk sample of 5 mm in diameter and 1 mm in thickness by the laser flash method from room temperature to 1173 K, and the thermal conductivity was determined by the measured thermal diffusivity and density, and the reported specific heat capacity. The thermal diffusivity of Technetium decreases with increasing temperature though it is almost constant above 600 K. The thermal conductivity of Technetium shows a minimum around 400 K, above which the thermal conductivity increases with temperature. The electronic and phonon components of the thermal conductivity were evaluated approximately. The increase in the thermal conductivity of Technetium with temperature is due to the increase in the electronic component.
