Platinum Oxidation States
Platinum (Pt, Z=78) commonly shows +2 and +4 oxidation states. The +2 state drives square-planar coordination (cisplatin); +4 appears in PtO₂ and PtCl₄. This page covers all known states, electron configuration, and key compounds.
Use the Platinum Oxidation States
Platinum displays a wide range of oxidation states from −2 to +6, but +2 and +4 are by far the most common in ordinary chemistry. The +2 state produces characteristic square-planar d8 complexes (cisplatin, [PtCl₄]²⁻); the +4 state gives octahedral d6 complexes (PtCl₄, [PtCl₆]²⁻). Relativistic contraction of the 6s orbital and large crystal-field stabilization energy lock platinum into these two preferred states.
| State | d-count | Stability | Notes |
|---|---|---|---|
| -2 | d¹⁰ | Rare | Found in intermetallics such as Cs₂Pt and Ba₂Pt. Pt carries a formal negative charge due to electron transfer from the electropositive alkali/alkaline-earth metal. |
| -1 | d¹⁰s¹ (formal) | Very rare | A formal electron count for highly reduced platinum; actual electrons may be delocalized across Pt–Pt bonded clusters, so local d-count assignments are model-dependent. |
| 0 | d¹⁰ | Stable | Elemental platinum metal and zero-valent organometallic complexes such as Pt(PPh₃)₄ and Pt(dba)₂. Extensively used in homogeneous catalysis. |
| +1 | d⁹ | Rare | Occurs in Pt–Pt bonded dimers (e.g. [Pt₂(μ-CO)₂Cl₄]²⁻). Not common as a mononuclear species. |
| +2 | d⁸ | Common | Most prevalent state. Square-planar geometry due to d⁸ crystal-field splitting. Includes cisplatin ([PtCl₂(NH₃)₂]), [PtCl₄]²⁻, PtO, and PtCl₂. Key in anticancer drugs and catalysis. |
| +3 | d⁷ | Uncommon | Seen in binuclear Pt(III)–Pt(III) complexes bridged by acetate or similar ligands. Mononuclear Pt(III) is rare due to the odd d-electron count. |
| +4 | d⁶ | Common | Second-most common state. Octahedral low-spin d⁶ geometry. Includes PtO₂, PtCl₄, [PtCl₆]²⁻ (chloroplatinic acid anion), and the prodrug oxaliplatin precursor. |
| +5 | d⁵ | Very rare | Reported in PtF₅; unstable with respect to disproportionation to Pt(IV) and Pt(VI). Characterization confirmed by X-ray crystallography. |
| +6 | d⁴ | Rare | PtF₆ — an extremely powerful oxidizer. Famous for oxidizing xenon (Xe + PtF₆ → Xe⁺[PtF₆]⁻) and molecular oxygen. Only stable in the perfluoride. |
IE1 = 870 kJ/mol | IE2 = 1791 kJ/mol | IE3 = 2800 kJ/mol (est.)
The high first ionization energy reflects relativistic stabilization of the 5d/6s electrons. The accessible +2 and +4 states correspond to sequential loss of the weakest-bound d-electrons from the anomalous 5d⁹ 6s¹ ground state.
Summary
Platinum (Pt) is a Group 10 d-block transition metal with atomic number 78. Its filled or near-filled 5d shell and relativistic effects give it exceptional stability, corrosion resistance, and rich coordination chemistry. The dominant oxidation states are +2 (square-planar complexes, cisplatin, PtCl₂) and +4 (octahedral complexes, PtO₂, PtCl₄). Unusual states from −2 to +6 have been characterized in specific compounds. This reference covers all known oxidation states, their electron configurations, stability drivers, and the most important Pt compounds.
How it works
- Click a tab — Oxidation States, Compounds, Electron Config, or Physical Props — to explore each category.
- The Oxidation States panel lists every known state from −2 to +6 with stability ratings and notes.
- The Compounds panel covers the most important Pt complexes grouped by oxidation state.
- The Electron Config panel shows the anomalous 5d⁹6s¹ ground state, relativistic effects, and ionization steps.
- The Physical Props panel provides atomic mass, density, melting point, and electrochemical data.
- Click any monospace table cell to copy its value to your clipboard.
Use cases
- Students studying d-block transition metals and oxidation state trends across Period 6.
- Chemistry teachers preparing material on platinum-group metals or coordination chemistry.
- Medicinal chemists and pharmacologists reviewing cisplatin and platinum-based anticancer drug mechanisms.
- Catalysis researchers needing quick data on Pt oxidation states in heterogeneous or homogeneous systems.
- Materials engineers working with platinum catalysts, catalytic converters, or platinum electrodes.
- Anyone preparing for chemistry exams covering Group 10 or 5d transition metals.