Paper: CSIR-NET June 2016 · Subject: Inorganic Chemistry · Chapter: Inorganic Spectroscopy · Topic: Inorganic Spectroscopy – General · Marks: 2 · Difficulty: Medium
Identify correct statements for the EPR spectrum of $\mathrm{VO(acac)_2}$ [with square pyramidal geometry at vanadium] at 77K [ I $\left({}^{51}\mathrm{V}\right)=7/2$ ](A) It has two g values(C) It has one g value(B) It has 8 lines only(D) It has two patterns of 8 lines each.Correct statements are -
(a)A and D
(c)B and C
(b)A and C
(d)B and D
Answer
Answer: A ✓ checked by 4AB · confidence high
Key A unchanged; explanation rewritten because 'Answer: (a) and (d)' read as two options rather than statements A and D.
Explanation
VO(acac)₂ is a d¹ V(IV) complex with axial (square-pyramidal, C₄ᵥ) symmetry. In a frozen solution at 77 K the spectrum is anisotropic, so two g values are seen, g∥ and g⊥ — statement A is true and C is false.
Each g component is split by ⁵¹V (I = 7/2) into 2I + 1 = 8 hyperfine lines, giving two patterns of 8 lines each — statement D is true and B is false.