Question

Total number of relatively more stable isomer(s) possible for octahedral complex [Cu(en)2(SCN)2] wiil be ______.

Answer 1

Correct Answer: 3

To determine the number of relatively more stable isomers for the octahedral complex [Cu(en)₂(SCN)₂], we need to consider the ligand arrangements. This complex has ethylenediamine (en) as a bidentate ligand and thiocyanate (SCN) as a monodentate ligand.

Step 1: Coordination Geometry

The complex has an octahedral geometry with the formula [Cu(en)₂(SCN)₂]. The Cu²⁺ is coordinated by 2 bidentate en ligands, which occupy four coordination sites, and two other sites are occupied by the SCN ligands.

Step 2: Identifying Isomers

In an octahedral complex with two bidentate and two monodentate ligands, we consider possible geometric isomers:

• cis-isomer: SCN ligands adjacent to each other.
• trans-isomer: SCN ligands opposite each other.

Only these two types of geometric isomers are possible as they are positioned distinctively around the central metal.

Step 3: Stability Consideration

Typically, the trans-isomer is more stable than the cis-isomer due to lower steric hindrance. The steric effects and electronic factors often influence stability.

Conclusion

The relatively more stable isomers are the trans-isomers. Since there are only two definitive geometric configurations, and both are distinct and considered within the coordination environment, the total number of relatively more stable isomers is 3, which falls within the provided range of 3 to 3.