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

Gene Senges,Lin Li,Artur Wodyński,Helmut Beckers,Martin Kaupp,Sebastian Riedel,Robert Müller

doi:10.1002/chem.202102055

Gene Senges, Lin Li + Show 5 more

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https://doi.org/10.1002/chem.202102055

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Abstract

Molecular platinum fluorides PtF n , n=1–6, are prepared by two different routes, photo‐initiated fluorine elimination from PtF6 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 PtF3, PtF4 and PtF5. Photolysis of PtF6 enabled a highly efficient and almost quantitative formation of molecular PtF4, whereas both PtF5 and PtF3 were formed simultaneously by subsequent UV irradiation of PtF4. 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 PtF4, for which a spin‐triplet (3B2g, D 2h) coexists with an electronic singlet state (1A1g, D 4h) in solid neon matrices.

Highlights

The most common oxidation states for platinum are + 2 and + 4, but PtF6 and the ions PtF6À and PtF62À are probably the best known and most investigated binary platinum fluoride species.[1]
We have studied the photochemistry of PtF6 isolated in solid noble-gas matrices
The two IR active fundamentals of octahedral PtF6 are observed at ν3 = 705.6 cmÀ 1 (Figure 2) and ν4 = 274.6 cmÀ 1 (Figure S2.3 in the Supporting Information), where the former is accompanied by a weaker matrix site at 709.1 cmÀ 1 (Figure 2)

Summary

Introduction

Dioxygenyl salt, [O2]+ [PtF6]À , and of the first xenon compounds, likely [FXe]+ [PtF6]À and [FXe]+ [Pt2F11]À .[1a,b,7]. In a previous computational study, only even-numbered molecular platinum fluorides PtF2n (n = 1–4) were studied by scalar relativistic density functional and coupled-cluster methods.[16] more recent studies on PtF6[17], PtF62À ,[18] PtX42À (X = F, Cl, Br)[19] and the related PdF4[20] have shown that SOC effects have a dramatic impact on their electronic structure and spectra. Give, in accordance with experimental structural and spectroscopic data, a diamagnetic octahedral molecule with a closedshell singlet ground state (Figure 1).[1b] PtF6 represents the rare case where relativistic spin–orbit splitting leads to a qualitative change of molecular and electronic structure in a stable molecule.[1b]

Results and Discussion

Conclusion

Conflict of Interest