Rhenium electron configuration

As expected there is a close resemblance in the chemical behaviour of technetium and rhenium whereas the properties of both elements differ considerably from those of manganese. The electronic configuration of technetium in the ground state is 4d 5s. Technetium is a silver-grey metal which tarnishes slowly in moist air. 

Rhenium has a 5d56. electron configuration and all oxidation states from 0 to 7+ are known, although the heptavalent is the most stable state. 

Electronic configurations of ions are obtained in much the same way as those of elements. The fluorine atom has nine electrons, so the F ion (with ten electrons) would have the same configuration as Ne gas. Similarly, the sulfide ion (S2 ) would have the argon structure. All monatomic negative ions in ordinary systems have rare gas configurations (except for a negative ion of rhenium which has been reported). 

Consider the compounds of a given metal such as rhenium. Then consider a three-dimensional matrix with the three independent, discrete variables electronic configuration E)y coordination number (C), and ionic charge (Q) corresponding to the three dimensions. The known rhenium complexes can be placed in this matrix in the appropriate cells corre-... 

Additional results for comparing analogous compounds of technetium and rhenium with respect to both reactivity and thermodynamic stability would be desirable, taking into account electron configurations, molecular structures, and strength of bonding and of ligand fields. 

About 400 compounds containing the T12-H2 ligand have been made that are stable. Almost all of them are octahedral with the metal in the d electron configuration, from Cr(0) to W(0) across the periodic table to Rh(lll) and Ir(III). There are a few dihydrogen complexes known with metals in other oxidation states. These are relatively rare. There are seven coordinate rhenium compounds like [Re(H2)(H)2(CO)(PMe2Ph)3]+ [8] and very unstable d systems like [Pt(ll2-H2)(PR3)2H]+ [9]. Neutral and cationic complexes are known but not anionic ones. Presumably anionic dihydrogen complexes are unstable because the metal s dTC electron richness promotes the oxidative cleavage of the H-H bond by d7t(M) —> o (H2) donation. 

Rhenium appears in the complex as Re +, with the electronic configuration 5d). If we place the z-axis along the Re Re bond and the Q ions in the planes bisecting the xz- and yz-planes, we can write the configuration as Sd 2) Sd 2 f) Sd 2) My2) with all spins parallel. The (5dlg,)-orbital is empty because of the interaction with the Cl 3/>-orbitals. We can thus, in principle, form a quadruple bond between the two Re ions. Cotton noted already in 1965 that this bonding pattern explains the eclipsed structure of the ion, which allows one of the the 3 f5-orbitals to be involved in the Re Re bonding. ... 

As observed in Table 1.8 most examples of compounds with electron configuration arise from rhenium chemistry. The most important group of... 

Rhenium (+4) has a 5d electronic configuration. When the ion is placed in an octahedral field the following terms in order of increasing energy result within the t g configuration A2g, Eg, T,g and T2g. These terms are further split by spin-orbit interaction into states denoted in the Bethe notation as T (i = 6,7,8)... 

The configuration of rhenium(I) requires ligand systems which are able to accept electron density from the electron-rich metal center. Thus, frequently phosphines, nitrogen heterocycles, carbonyls, or isocyanides are encountered. Most of the octahedral products possess a high thermodynamic stability and kinetic inertness as is expected for 18-electron systems. 

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