Based on the crystal-field strengths f- < ch2cn < nh3 < no2- < cn- which co(iii) complex is most likely high-spin?
a. [co(nh3)6]3+
b. [co(no2)6]3-
c. [co(cn)6]3-
d. [cof6]3-
e. [co(ch2cn)6]3+
f. [cof5(nh3)]
g. none of the above
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D. [CoF₆]³⁻

Explanation:

In the weak field octahedral complexes of 3d series, the value of the ∆₀ is very small as there will be no pairing of d- electrons. These type of complexes have the maximum number of the unpairing electrons and are called high spin or spin free complexes.

As stated above, The complex with weak field ligands corresponds to high spin complex. The trend for the crystal field strength is given in the question. So, F⁻ corresponds to the least weak field ligand and thus, D is the most likely high spin complex.