Question

Which of the following is not correctly matched?

• A. [Fe(en)3]3+ - sp3d2 and paramagnetic
• B. [FeCl4 ]2– - sp3 and paramagnetic
• C. [Fe(CN)6]3– - d2sp3 and paramagnetic
• D. [Fe(CO)2(NO+)2] - sp3 and diamagnetic

Answer 1

Answer: (A)

$Fe(en)3$3+ - sp3d2 and paramagnetic

Answer 2

(1) [Fe(en)3]3+ - d2sp3 with one unpaired electron. 'en' is a strong field chelating ligand and thus compels for the pairing of electrons to have d2sp3 hybridisation. It is paramagnetic with one unpaired electron (valence shell electron configuration, 3d5)

(2) [FeCl4 ]2– - sp3 with four unpaired electrons. It is paramagnetic with four unpaired electrons (valence shell electron configuration, 3d6).

(3) [Fe(CN)6]3– - d2sp3 with one unpaired electron. 'CN–' is a strong field ligand and, therefore, it compels for pairing of electrons to have d2sp3 hybridisation. It is paramagnetic with one unpaired electron (valence shell electron configuration, 3d5)

(4) [Fe(CO)2(NO+)2] - sp3 and diamagnetic. Iron is in –II oxidation state. So,

[Fe(CO)2(NO+)2]