How many unpaired electrons are there in the complex ion [Co(NO₃)₆]⁴^-? For this ion the nitrate ligands produce a very strong crystal field. A)1 B)2 C)3 D)4 E)5

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In the complex ion [Co(NO3)6]4-, cobalt is in the +2 oxidation state (Co2+). With strong field ligands like nitrate, the crystal field splitting is large, causing the electrons to pair up in the lower energy t2g orbitals. Co2+ has a d7 configuration, and with strong field ligands, it will have one unpaired electron.

How Many Unpaired Electrons Are There in the Complex Ion