Question

A metal complex having composition Cr (NH3)4Cl2Br has been isolated in two forms A and B. The form A reacts with AgNO3 to give a white precipitate readily soluble in dilute aqueous ammonia whereas B gives a pale yellow precipitate soluble in concentrated ammonia.

(i) Write the formulae of isomers A and B.

(ii) State the hybridisation of chromium in each of them.

(iii) Calculate the magnetic moment (spin only value) of the isomer A

Answer 1

(a) Isomer A: [Cr(NH3)4 BrCl ]Cl

Isomer B: [Cr (NH3)4 Cl2]Br

(b) Hybridisation of Cr in isomer A and B is d2sp3.

(c) Number of unpaired electrons in Cr3+(3d3) is 3