Chemistry - Coordination Chemistry Question with Solution | TestHub
Which of the following complexes against their indicated properties is INCORRECT
Options:
Answer:
Solution:
A. Tetraamminedichloridochromium(III) chloride: . Cr(III) is a d³ system. Octahedral d³ complexes are always paramagnetic (3 unpaired electrons). It has two chloride ligands and four ammonia ligands, allowing for cis-trans isomerism. This statement is CORRECT.
B. Pentaaquachloridotitanium(III) nitrate: . Ti(III) is a d¹ system. Octahedral d¹ complexes are paramagnetic (1 unpaired electron). It can exhibit ionization isomerism with the nitrate ion, e.g., . This statement is CORRECT.
C. Amminechlorido(ethylenediamine)platinum(II) nitrate: . Pt(II) complexes are typically square planar and d⁸. Square planar d⁸ complexes are diamagnetic. It can exhibit ionization isomerism with the nitrate ion, e.g., . This statement is CORRECT.
D. Tetraamminedinitratocobalt(III) nitrate (high-spin): . Co(III) is a d⁶ system. If it were high-spin, it would have 4 unpaired electrons and be paramagnetic. However, Co(III) complexes are almost exclusively low-spin and diamagnetic. The statement specifies "high-spin", which would make it paramagnetic. The complex has two nitrate ligands and four ammonia ligands, allowing for cis-trans isomerism. The error here is that Co(III) is almost always low-spin and diamagnetic, even with weak field ligands like nitrate. Therefore, a high-spin Co(III) complex being paramagnetic is generally not observed. This statement is INCORRECT because Co(III) is typically low-spin and diamagnetic.