Molybdenum electron configuration

Write the electron configurations of the chromium, molybdenum, tungsten, and uranium atoms. Why are the sizes of molybdenum and tungsten atoms almost the same Which oxidation states are exhibited by the most stable compounds of these elements (for example, their natural compounds) Explain the observed laws. 

In keeping with its 4d%5s electron configuration, molybdenum forms many compounds in which its oxidation state is 6+. to an even greater extent than chromium. Also, like chromium, it forms compounds in which II is divalent and those in which it is trivalenl unlike chromium, il forms a number of pentavalenl compounds, and a few more tetravalent compounds, especially complexes. 

In keeping witii its 5d 6s2 electron configuration, tungsten forms many compounds in which its oxidation state is 6+, just as molybdenum does. It forms divalent and tetravalent compounds to about the same extent as molybdenum but its bivalent and pentavalent compounds are somewhat fewer. Its anion chemistry is closely akin to that of molybdenum. 

For example, [MoC+,]3 has a total of thirty-nine valence electrons from the molybdenum 4d5 5s and six chlorine 3p5 configurations, and the —3 charge on the ion. Its electron configuration is therefore cr12 n24 (2/2 )3. Thus the MO theory of these ML6 complex ions confirms that the electrons of prime importance are those occupying the t2g and eg levels on the metal, as predicted by crystal-field theory. However, the MO theory points the way to the more accurate calculation of electronic structure and properties. 

In addition to the above parameters, determined from the microwave data, the metal Fermi contact interaction constants in 97 MoN and 53 CrN were determined from the optical spectra [72] to be -508 and -179.8 MHz respectively. The element molybdenum belongs to the 4d transition metal row, which we will discuss further in due course. For the CrN molecule in its ground state, ab initio calculations [73] and molecular orbital considerations [74] suggest that the dominant electron configuration may be written... 

As used here cluster refers to molecules that contain at least 3 metal atoms and electron configurations suitable for the formation of metal-metal bonds. Molybdenum readily forms strong homoleptic metal-metal bonds (see Homoleptic Compound) and so it is not surprising that molybdenum is readily incorporated into cluster stractures (see Polynuclear Organometallic Cluster Complexes). 

Increasing the number of electrons reduces the activation of N2, because the electrons occupy the orbitals which are bonding with respect to the NN bond, and actually stabilize it. In agreement with this prediction dinitrogen is sufficiently activated to be reduced by protonation by dinuclear complexes of titanium(II), zirco-nium(Il), niobium(III), tantalum(III), molybdenum(IV), and tungsten(IV), whereas it is not reduced by protonation by certain d -d complexes, such as those of molybdenum(O), ruthenium(II), or rhodium(I). Apparently dinuclear complexes M-N=N-M in which M has the d electronic configuration can be intermediates in dinitrogen reduction in protic media, particularly if they represent part of polynuclear complexes (vide infra). 

The role of molybdenum (if there is no direct Mo-N bonding in the complex with the substrate) is not quite clear, but it can be speculated that Mo with d electronic configuration present in the cofactor reduces the number of electrons (compared... 

In the case of manganese(I), with an electronic configuration of 3d , the four-electron donor group RCO— would meet the EAN rule. Indirect support to the suggestion of a small steady state concentration of this type of intermediate along the reaction profile comes from isolation of stable rj -coordinated acyl complexes of ruthenium(II) , of group IVA transition elements and of thorium , all in the highest oxidation state. Also > -acyl complexes of vanadium(I) ° and niobium(V) have been reported. Most of the molybdenum acyl complexes are of the type . 

---