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)]^(+)`
B. `[Fe(en)(bpy)(NH_(3))_(2)]^(2+)`
C. `[Co(OX)_(2)(OH)_(2)]^(2-)`
D. `[Ti(NH_(3))_(6)]^(3+)`

Answer

C

Explanation

Ox. State of V in (a) :
x+2(-1)+2(-1)+0=+1 or x=+5
`therefore` Valence shell config. = `3d^(0)` (i.e., no unpaired electron)
Ox state of Fe in (b) : x+0+0+0=+2
or x = + 2
`therefore` Valence shell config. = `3d^(6)` (i.e., 4 unpaired electrons)
Ox. state of Co in (c ) : x+2(-2)+2(-1)=-2
or x=+4
`therefore` Valence shell config. `=3d^(5)` (i.e., 5 unpaired electrons)
Ox state of Ti in (d) : x+6(0)=+3 or x=+3
`therefore` Valence shell config. = `3d^(1)` (i.e., 1 unpaired electron)
Thus, complex of cobalt has maximum unpaired electrons (viz. 5) and hence has highest paramagnetism.