Chapter 6 Multiple Choice Questions

. Calculate the approximate g values for the low spin d⁵Fe³⁺ ion shown in Fig. 6.10.

g₁ = 2.35; g₂ = 2.19; g₃ = 1.65

g₁ = 2.87; g₂ = 2.29; g₃ = 1.57

g₁ = 2.05; g₂ = 2.00; g₃ = 1.95

g₁ = 2.09; g₂ = 2.30; g₃ = 1.75

g₁ = 2.99; g₂ = 2.01; g₃ = 1.90

. Calculate the approximate spin Hamiltonian parameters (g and A) for the square pyramidal Cu²⁺ ion shown in Fig. 6.6(b).

= 2.32; = 2.15; = 18.0 mT; ≈ 4.0 mT

= 2.19; = 2.10; = 16.0 mT; ≈ 3.5 mT

= 2.39; = 2.00; = 12.0 mT; ≈ 2.5 mT

= 2.27; = 2.20; = 20.0 mT; ≈ 1.5 mT

= 2.29; = 2.05; = 14.0 mT; ≈ 3.0 mT

. Calculate the approximate spin Hamiltonian parameters (g and A) for the low spin [Cr(CO)₄(dppe)]⁺ complex shown in Fig. 6.13(b).

= 1.98; = 2.06; ≈ 2.4 mT; ≈ 2.5 mT

= 1.88; = 2.16; ≈ 2.8 mT; ≈ 2.0 mT

= 1.78; = 2.26; ≈ 3.2 mT; ≈ 1.5 mT

= 1.68; = 2.00; ≈ 3.4 mT; ≈ 3.5 mT

= 1.58; = 2.36; ≈ 3.6 mT; ≈ 3.0 mT

. The predicted g and A values for a d⁹ metal (M) complex of cis-M(CO)₄X₂ with C_2vsymmetry are:

g₁ = g₂ ≠ g₃; A₁ = A₂ ≠ A₃

g₁ = g₂ = g₃; A₁ = A₂ = A₃

g₁ ≠ g₂ ≠ g₃; A₁ ≠ A₂ ≠ A₃

g₁ ≠ g₂ = g₃; A₁ ≠ A₂ ≠ A₃

g₁ ≠ g₂ = g₃; A₁ = A₂ = A₃

. The predicted g values for the [Mo^IV=O(L)₅] complex are:

g₁ > g_e > g₃ = g_e

g₁ = g₂ > g_e > g₃

g₁ = g₂ = g_e > g₃

g₁ > g₂ > g₃ > g_e

g_e > g₁ = g₂ > g₃

. The dihedral angle (φ) for the radical can be calculated using the anisotropic hyperfine values given in exercise 6.5 (A_xx= ±18.1; A_yy= ±17.7 A_zz= ±22.4 mT). Calculate the approximate value for φ.

127.8°

106.3°

135.9°

142.3°

122.0°

. The predicted g values for the diatomic ClO^- radical are:

g₁ > g_e > g₃ = g_e

g₁ > g₂ > g₃ ≈ g_e

g₁ = g₂ > g_e > g₃

g_e > g₁ = g₂ > g₃

g_e > g₁ > g₂ = g₃

. The anisotropic hyperfine parameters for the ¹⁷O₂^- radical were found to be A_xx = -7.63, A_yy = +0.72, A_zz = +0.83 mT. Using this information, calculate the isotropic and dipolar components of the hyperfine tensor.

a_iso = +1.23 mT; B_xx = -1.6, B_yy = 4.75, B_zz = 6.86 mT

a_iso = -0.06 mT; B_xx = -2.6, B_yy = 3.75, B_zz = 8.86 mT

a_iso = -2.03 mT; B_xx = -5.6, B_yy = 2.75, B_zz = 2.86 mT

a_iso = +0.50 mT; B_xx = -4.6, B_yy = 5.75, B_zz = 5.86 mT

a_iso = -1.34 mT; B_xx = -3.6, B_yy = 0.75, B_zz = 1.86 mT

. The anisotropic g and A values for a surface stabilised N₂^- radical were found to be g_xx = 2.0018, g_yy = 2.0042, g_zz = 1.9719, A_xx = -0.29, A_yy = +2.15, A_zz = -0.42 mT. Using this information, calculate the s and total p orbital spin densities on¹⁴N (given A₀ = 64.6 mT and b₀= 3.962 mT):

ρ_s = 0.074; ρ_p = 0.454

ρ_s = 0.152; ρ_p = 0.354

ρ_s = 0.238; ρ_p = 0.254

ρ_s = 0.296; ρ_p = 0.554

ρ_s = 0.002; ρ_p = 0.654

. Which one of the following statements is true:

Large and positive g shifts are observed when the LUMO – HOMO gap is small and λ is positive.

Large deviations in g occurs when the energy difference between the SOMO and lowest lying excited state is large.

A large deviation of g from g_e is expected when λ is large and the energy difference between the SOMO and the lowest lying excited state is small.

A small deviation of g from g_e is expected when λ is small and positive.

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