Predict the geometry, the d orbital energy-level diagram, and the number of unpaired electrons in

(a) [Ni(CN)₄]^2- and

(b) [FeBr4]^-.

Strategy Based on the d electron configuration of the metal ion, decide whether the four-coordinate complex is tetrahedral or square planar. Use the appropriate diagram from Figure 19.25 or 19.26 to write the orbital energy-level diagram, and determine the number of unpaired electrons.

Figure 19.26