Rhenium atomic properties

Field emission microscopy was the first technique capable of imaging surfaces at resolution close to atomic dimensions. The pioneer in this area was E.W. Muller, who published the field emission microscope in 1936 and later the field ion microscope in 1951 [23]. Both techniques are limited to sharp tips of high melting metals (tungsten, rhenium, rhodium, iridium, and platinum), but have been extremely useful in exploring and understanding the properties of metal surfaces. We mention the structure of clean metal surfaces, defects, order/disorder phenomena,... 

Rhenium is one of the oxophilic atoms effective for oxidation reactions. ReOx species are likely to have chemical interaction with various oxide supports and exhibit unique catalytic properties that cannot be observed on monomeric rhenium oxides. A new active six-membered octahedral Re cluster in zeolite pores (H-ZSM-5 [HZ]) is produced from inactive [Re04] monomers in situ under selective propene oxidation to acrolein (C3H6+02 - CH2=CHCH0+H20) in the presence of ammonia that is not involved in the reaction equation [16], The cluster is transformed back to the original inactive monomer in the absence ammonia. Note that coexistence of spectator NH3 is indispensable for the selective oxidation. 

Like rhenium and ruthenium it crystallizes in a closest packed hexagonal lattice with the metal atoms having the coordination number 12. In Table 2 some properties of technetium are compared with those of manganese and rhenium. 

As the central member of the triad of metals in group 7, technetium (period 5) has similar physical and chemical properties as its partners manganese (period 4) above it and rhenium (period 6) below it. The sizes of their atomic radii do not vary greatly Mn = 127, Tc = 136, and Re = 137. Neither does their level of electronegativity vary significantly Mn = 1.5, Tc =... 

Hirschmann M. (1991). Thermodynamics of multicomponent olivines and the solution properties of (Ni,Mg,Ee)2Si04 and (Ca,Mg,Fe)2Si04 olivines. Amer. Mineral, 76 1232-1248 Hirt B., Herr W, and Hoffmeister W. (1963). Age determinations by the rhenium-osmium method. In Radioactive Dating, International Atomic Energy Agency, Vienna. 

Among the fission products of uranium, one unidentified substance remained. O. Hahn, Lise Meitner, and F. Strassmann (47) had found a substance with a half-life of 23 minutes which they considered an isotope U285. In 1940 Edwin McMillan at the University of California in Berkeley, while investigating the properties of this isotope, discovered another substance associated with it which had a half-life of 2.3 days. He at once suspected that this might be the element with atomic number 93. A chemical study of the substance was made by E. Segre (48). This showed that the substance did not have properties similar to those of rhenium, as was expected of 93. Rather, the substance resembled the rare earths. In spite of this, McMillan did not lose interest in this material. 

In the case of technetum, this is the most practically used element among non-/ radioactive ones for medical and technical purposes [283], so the permanent interest in its coordination chemistry (in particular, the structural aspect of its compounds [547] and kinetics of substitution reactions [548]) is not surprising [549]. The theoretical interest in Tc is provoked, in particular, by the fact that this is a rhenium analogue. This element (Re) forms multiple metal-metal bond complexes and has been studied intensively in order to achieve a better understanding of the physical and chemical properties of multiple bonds between metal atoms [533],... 

---