Matrix Isolation Spectroscopic and Relativistic Quantum Chemical Study on Molecular Platinum Fluorides PtFn (n = 1-6) Reveals Magnetic Bistability of PtF4.

Molecular platinum fluorides PtF n , n = 1-6, are prepared by two different routes, the photo-initiated fluorine elimination from PtF 6 embedded in solid noble-gas matrices, and the reaction of elemental fluorine with laser ablated platinum atoms. IR spectra of the reaction products isolated in rare-gas matrices at cryogenic conditions provide for the first time experimental vibrational frequencies of molecular PtF 3 , PtF 4 and PtF 5 . Photolysis of PtF 6 enabled a highly efficient and almost quantitative formation of molecular PtF 4 , while both PtF 5 and PtF 3 were formed simultaneously by subsequent UV irradiation of PtF 4 . The vibrational spectra of these molecular platinum fluorides were assigned with the help from one- and two-component quasirelativistic DFT computations to account for scalar relativistic and spin-orbit coupling effects. Competing Jahn-Teller and spin-orbit coupling effects result in a magnetic bistability of PtF 4 , for which a spin-triplet ( 3 B 2g , D 2h ) coexists with an electronic singlet state ( 1 A 1g , D 4h ) in solid neon matrices.