Which of the following complexes exhibits the highest paramagnetic behaviour?
where gly=glycine, en=ethylenediamine and bipy =bipyridyl
(At. no. `Ti=22, V=23, Fe=26, Co=27`)

Options

A. `|V(gly)_(2)(OH)_(2)(NH_(3))_(2)|^(2+)`
B. `|Fe(en)(bpy)(NH_(3))_(2)|^(3+)`
C. `|Co(OX)_(2)(OH)_(2)|^(2-)`
D. `|Ti(NH_(3))_(6)|^(3+)`

Answer

C

Explanation

Oxidation state of V in (A) `x + 2 (-1) + 2(-1) +` = `+1` or x = `+5`
Valence shell configuration `3d^(0)`
Number of unpaired electron 1.
Oxidatios state of Fe in (B) `x + 0 + 0 + 0 = +2` or = `+2`
Valence shell configuration = `3d^(6)` (i.e. 4 unpaired electrons)
Oxidation state of Co in (C) `x+ 2 (-2) + 2(-1) = -2 or x = +4`
Valence shell configuration = `3d^(5)` (i.e. 5 unpaired electron)
Oxidation state of Ti in (D)
`x + 6(0) = + 3 or x = +3`
Valence shell configuration = `3d^(1)` (i.e. 1 unpaired electron).
Thus complex of cobalt has maximum unpaired electrons (viz 5 ) and hence has highest paramagnetism.