 Solution

ID: past-exam-of-the-chemistry-b-course-of-the-university-of-cambridge/2023/paper-2/b6/a/iii/solution

platinum is in group 10, so subtracting its oxidation state gives $d^{8}$ for Pt(II) and $d^{6}$ for Pt(IV). Adding two electrons from each coordinated donor gives the local valence electron counting results

cisplatin : satraplatin : 8 + 2 (2)_{N H_{3}} + 2 (2)_{Cl} = 16, 6 + 2 (2)_{amine} + 2 (2)_{Cl} + 2 (2)_{OAc} = 18.

Each acetate in the depicted structure is monodentate, binding through one oxygen. The 16-electron count of the square-planar complex is normal for a low-spin late-metal

d^{8}

centre; it is not a missing ligand inferred from the 18-electron rule.

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