PrayogX › Chemistry › Chemical Bonding and Molecular Structure

O2 + PtF6 -> O2+[PtF6]- : bond order of the dioxygenyl cation, d-electrons of Pt(V), oxidant or fluorinating agent

Oxygen gas meets the deep-red vapour of PtF6 and an orange-red ionic solid appears. Press start and the lab does the rest: an ionisation-energy scale shows why one electron jumps, oxidation numbers show who is reduced, the MO diagram of O2 fills and loses one pi* electron to give bond order 2.5, platinum is stripped to Pt(V) 5d5, and every fluorine atom is counted before each option is tested claim - evidence - verdict. No prediction stage - input, run, watch, result.

Sub-topics covered

• Bond order from MO electron configurations - O2, O2+, O2-, O2 2-
• Paramagnetism and unpaired electrons in MO theory
• Bond order and bond length
• Oxidation states and electron configuration of transition-metal ions (Pt 5d9 6s1)
• Octahedral d-orbital splitting, low spin 5d ions
• Oxidant versus fluorinating agent - Bartlett's O2+[PtF6]-

What it teaches

• PtF6 has a very high electron affinity (about 7 eV) and takes one electron from O2 (IE 12.07 eV): O2 + PtF6 -> O2+[PtF6]-, so X+ = O2+ and Y- = [PtF6]-
• O2+ has 15 electrons; the electron removed from O2 was antibonding (pi*2p), so bonding 10 and antibonding 5 give bond order 2.5 - not 1.5, which is superoxide O2-: (A) false
• In [PtF6]- platinum is +5; Pt [Xe]4f14 5d9 6s1 loses 6s1 and four 5d electrons, leaving 5d5 (t2g5): (B) true
• Pt goes from +6 in PtF6 to +5 in [PtF6]-: PtF6 is reduced, so it is the oxidant: (C) true
• All six F atoms stay on Pt and no O-F bond forms - no fluorine is transferred, so PtF6 is not acting as a fluorinating agent: (D) false
• Bartlett noticed IE(Xe) 12.13 eV is almost the same as IE(O2) and made the first noble-gas compound the same year

Simulation ID

• ADV-2026-P1-CHE-Q07 · revision 1

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