Matrix Isolation Spectroscopic and Relativistic Quantum Chemical Study of Molecular Platinum Fluorides PtF( n ) (n=1–6) Reveals Magnetic Bistability of PtF(4)

Molecular platinum fluorides PtF( n ), n=1–6, are prepared by two different routes, 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 under 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), whereas 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 of one‐ and two‐component quasirelativistic DFT computation 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.