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Compute the effective atomic number (EAN) of the central metal in each complex: (a) K3[Cr(C2O4)3] (b) K4[Fe(CN)6]

1. (a) 33, (b) 36
2. (a) 36, (b) 36
3. (a) 35, (b) 34
4. (a) 36, (b) 35

Correct answer: (a) 33, (b) 36

Solution

EAN = Z - oxidation number + 2*(coordination number). For Cr(III) oxalate this gives 33; for the Fe(II) cyanide it reaches 36 (krypton configuration).

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