Question

State the types of isomerism that may be exhibited by the following complexes, and draw structures of the isomers: (a) [Co(en)2(ox)]+ (b) [Cr(ox)2(OH2)2]-, (c) [PtCl2(PPh3)2], (d) [PtCl2(Ph2PCH2CH2PPh2)] and (e) [Co(en)(NH3)2Cl2]+.

Answer 1

Co(en), (Ox) (a) The complex has optical isomers as shown below: en en Ox Ох en en

(b) The compound [Cr(ox), (OH2),T has geometrical isomers as shown below. ОН но, =0 and и О он НО trans cis The cis-isomer has optical isomers as shown below:

но Но, ОН шОн ОI! о о о

(c) The complex PICI, (PPh,)2 has square planner geometry and it has geometrical isomers as shown below: Ph -P. Ph Ph C1 Ph Ph Pt Pt Ph C1 Ph Ph Ph Ph Ph rans cis Ph

(d) In the complex [PICI, (Ph,PCH,CH,PPh,)], the ligand Ph,PCH,CH,PPh, is bidentate. The complex has square planner geometry. The bidentate ligand remains on the same plane of the compound as shown below: Ph Ph C1 НС н.с, -PH Ph Ph Therefore, the complex has no isomer. When a ligand is bidentate in square planner geometry, only cis arrangement is possible.

(e) The complex Co(en)(NH,), CI,has geometrical isomers as follows: C1 en HN Cl H,N HN 'NH3 cis trans The cis-isomer has optical isomers as shown below: en en Cl H3N 'NH3 Н.Nши 'NH3 Ci en