\({x}+6 \times(-1)=-4\)
\({x}=+2\)
\({Co}^{2+}:[{Ar}] 3 {~d}^{7}\)
and \({CN}^{-}\)is a strong field ligand which can pair electron of central atom.
It has one unpaired electron ( \(n\) ) in \(4d-\)subshell.So spin only magnetic moment \((\mu)=\sqrt{n(n+2)}\, B . M\)
where \({n}=\) number of unpaired electrons.
\(\mu=\sqrt{3} \,{~B} . {M} \quad \mu=1.73\, {BM}\)
(પરમાણુ ક્રમાંક : $Ti = 22, Cr = 24, Co = 27, Zn = 30$)
($en=$ ઇથિલીન ડાય એમાઈન)
$(en =$ ઇથેન $-1, 2-$ ડાયએમાઇન$)$
(પ. ક્ર.: $Sc = 21 , Ti = 22, V = 23, Zn = 30$)