Which of these transition metal complexes contain $3 d^{6}$ $3d^6$ metals?

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Which of these transition metal complexes contain $3 d^{6}$ $3d^6$ metals?

$A)$ $A)$ ${FeCl}_{3}$ $"FeCl"_3$
$B)$ $B)$ ${CoCl}_{3} {(py)}_{3}$ $"CoCl"_3("py")_3$
$C)$ $C)$ ${RuCl}_{2}$ $"RuCl"_2$
$D)$ $D)$ ${NiCl}_{2} {({PPh}_{3})}_{2}$ $"NiCl"_2("PPh"_3)_2$

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Answer 1 · 2017-08-16T01:00:42

The idea here is to know what the charges on the ligands are, and deduce the oxidation state of the central metal.

I got $B$ $B$ .

$A)$ $A)$ ${FeCl}_{3}$ $"FeCl"_3$ holds three ${Cl}^{-}$ $"Cl"^(-)$ (chloro) ligands, so the iron atom has an oxidation state of $+ 3$ $+3$ . Iron originally had...

$[A r] 3 d^{6} 4 s^{2}$ $[Ar]3d^6 4s^2$

but removing three valence electrons (which if you recall, come out of the $n s$ $ns$ first), the $+ 3$ $+3$ state would have...

$ul([Ar]3d^color(red)(5) 4s^0)$

so this is not it.

$B)$ $"CoCl"_3("py")_3$ , as before, contains three $"Cl"^(-)$ (chloro) ligands. You are actually expected to know that pyridine is a neutral ligand, so that means $"Co"$ has a $+3$ oxidation state.

Cobalt's neutral electron configuration was originally...

$[Ar]3d^7 4s^2$

so losing three electrons for the $+3$ state lands it on $ul(color(blue)(3d^6 4s^0))$ .

$C)$ $"RuCl"_2$ , as we can tell at this point, as $"Ru"("II")$ , or the $+2$ oxidation state. Ruthenium normally has a configuration of...

$[Kr] 4d^7 5s^1$

(which, by the way, is an Aufbau 'exception'.)

If you did mean $3d^6$ , $"Ru"$ doesn't apply; it has a

$ul([Kr] color(red)(4)d^6 5s^0)$

configuration with a $+2$ oxidation state... wrong period in the periodic table!

$D)$ $"NiCl"_2("PPh"_3)_2$ has two $"Cl"^(-)$ (chloro) ligands, and two triphenylphosphine (TPP) ligands. The TPP ligands are neutral, so the oxidation state on nickel is $+2$ .

The neutral configuration was...

$[Ar] 3d^8 4s^2$

And so, the $+2$ state has...

$ul([Ar] 3d^color(red)(8))$

which is not $3d^6$ .

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Which of these transition metal complexes contain $3 d^{6}$ $3d^6$ metals?

$A)$ $A)$ ${FeCl}_{3}$ $"FeCl"_3$
$B)$ $B)$ ${CoCl}_{3} {(py)}_{3}$ $"CoCl"_3("py")_3$
$C)$ $C)$ ${RuCl}_{2}$ $"RuCl"_2$
$D)$ $D)$ ${NiCl}_{2} {({PPh}_{3})}_{2}$ $"NiCl"_2("PPh"_3)_2$

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Which of these transition metal complexes contain 3d^63d63d^6 metals?

A)A)A) "FeCl"_3FeCl3"FeCl"_3 B)B)B) "CoCl"_3("py")_3CoCl3(py)3"CoCl"_3("py")_3 C)C)C) "RuCl"_2RuCl2"RuCl"_2 D)D)D) "NiCl"_2("PPh"_3)_2NiCl2(PPh3)2"NiCl"_2("PPh"_3)_2

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Which of these transition metal complexes contain $3 d^{6}$ $3d^6$ metals?

$A)$ $A)$ ${FeCl}_{3}$ $"FeCl"_3$
$B)$ $B)$ ${CoCl}_{3} {(py)}_{3}$ $"CoCl"_3("py")_3$
$C)$ $C)$ ${RuCl}_{2}$ $"RuCl"_2$
$D)$ $D)$ ${NiCl}_{2} {({PPh}_{3})}_{2}$ $"NiCl"_2("PPh"_3)_2$