試題詳解

28. Exchange of an H₂O ligand on [(CO)₃Mn(H₂O)₃]⁺is much more rapid than on [(CO)₃Re(H₂O)₃]⁺. The activation volume for the Mn case is -4.5 ± 0.4 cm³mol^-1. The Mn complex has infrared bands at 2051and 1944 cm^-1 that can be attributed to C-O stretching vibrations. Which of the following are correct?
(A) First row transition metal complexes are generally more substitutionally labile, thus more "weak-field" than second and third row complexes.
(B) The negative volume of activation is consistent with a D (or I_d) mechanism.
(C) Occurrence of two infrared bands of [(CO)₃Mn(H₂O)₃]⁺ is more consistent with a fac isomer.
(D) mer-[(CO)₃Mn(H₂O)₃⁺ is isostructural with mer-[(CO)₃Re(H₂O)₃]⁺.
(E) The C-O stretching vibrations observed in [(CO)₃Mn(H₂O)₃]⁺should have higher vibrational frequencies as compared to free CO.