The number of isoelectronic species among Sc3+, Cr2+, Mn3+, Co3+ and Fe3+ is ‘n’. If ‘n’ moles of AgCl is formed during the reaction of complex with formula CoCl3(en)2NH3 with excess of AgNO3 solution, then the number of electrons present in the t2g orbital of the complex is .
Answer
6
Solution
Number of electrons:
Sc3+ = 21 - 3 = 18, Cr2+ = 24 - 2 = 22, Mn3+ = 25 - 3 = 22, Co3+ = 27 - 3 = 24, Fe3+ = 26 - 3 = 23
only Cr2+ and Mn3+ are isoelectronic n = 2
1 mol of the complex gives 2 mol AgCl two Cl- are outside the coordination sphere.
Coordination number 6 = 2 en (bidentate, 4) + NH3 (1) + Cl (1)
complex is [Co(en)2(NH3)Cl]Cl2
Co3+: [Ar] 3d6; en and NH3 are strong field ligands low spin t2g6 eg0
electrons in t2g orbitals = 6
Answer: 6