Question

1. The chromium-chromium bonding in a molecule uses the 3d orbitals of the chromium atoms.

a. Draw the 3d orbitals of a chromium atom being sure to label the x, y and z axes. Standard convention is that the z-axis is parallel to the internuclear axis.

b. Draw the MO energy diagram for an isolated [Cr2]2+ fragment (no ligands!) assuming the interactions of only the 3d orbitals. Assume that the z-axis is parallel to the internuclear axis

c. Next to each energy level, draw pictures of the molecular orbitals for [Cr2]2+ .

d. Label the orbitals with the appropriate bond types (symbols).

e. Fill in the partial MO diagram constructed in part b with the proper number of valence electrons for chromium. Write the ground state electronic configuration, and determine the bond order of the dimer.

f. Based on your partial MO diagram, would you expect this molecule to be paramagnetic or diamagnetic? Why

Answer 1

a) The shapes of d-orbitals by taking z axis parallel to the internuclear axis are as follows b) According to Molecular Orbital Theory, the diagram for this molecule can be drawn by the help of atomic orbital configuration of Cr

3d ORBITALS OF CHROMIUM ATOM - dyz do y

Now the MOT diagram of this can depicted be as follows

For Count : 45' 345 autor - 7 [14/17 (7) 3d5 Cort - 11) 7 19 11

Also, (c) and (d) the shapes of the molecular orbitals formed by the overlap of d orbitals of similar energy are also drawn along with the symbols

Ys be Door T 프 hINI Beli SMO SMO si # INTHE ECD Q8 D E ->zare eveorto" #982- π blame.. X7 42-blow y MOLECULAR ORBITAL ENERGY DIAGRAM FOR [Croft

(e) the ground state electronic configuration for Cr₂²⁺ is given as

с . Кк ті? * * 2 *23*тер, тэр, Тер (п* 2Бт* 25 ) т* 2р: (т за), ты, T 3d S 3ch; 8 3 chp 242 BOND ORDER = No - NA - 28-18_5

where N_B is the no. Of bonding orbitals

And N_A is the no. Of anti bonding orbitals

F) the molecule is diamagnetic because there is no unpaired electron present