Structural analysis of anionic Pt(0) complexes achieved

Collaboration between scientists in Japan and France has demonstrated the first structural analysis of highly reactive anionic Pt(0) complexes. The breakthrough is based on stabilization by the electron-accepting boron compounds.

Anionic M⁰ complexes, where M represents group 10 metals, have been an area of interest in materials research as active species for catalytic reactions. However, one problem is that their molecular structures have very rarely been determined due to their extremely high reactivity. In particular, the structures of Pt⁰ complexes, which are viewed as exhibiting a high degree of reactivity, have not been determined, while their syntheses have been almost non-existent.

As reported in the journal Angewandte Chemie International Edition [Kameo et al. Angew. Chem., Int. Ed. (2023) DOI: 10.1002/anie.202301509], a team from Osaka Metropolitan University and the National Institute of Advanced Industrial Science and Technology in Japan, and Université de Toulouse and Université Paul Sabatier in France, showed the molecular structures of anionic Pt⁰complexes for the first time, with this achievement being underpinned by the stabilization of anionic Pt⁰ complexes – which tend to be unstable because of their electron-donating nature – by the electron-accepting properties of boron compounds.

While platinum complexes that present a range of catalytic activities have already been a keen source of research, until now anionic Pt⁰ complexes have remained unexplained. As Associate Professor Hajime Kameo, from Osaka Metropolitan University Graduate School of Science, pointed out, “The results of this research not only enable us to elucidate the properties and functions of highly active chemical species but also provide new guidelines for their creation. It is expected to lead to the development of innovative catalytic reactions mediated by these chemical species.”

In their paper, entitled ‘Square-Planar Anionic Pt⁰ Complexes’, very unstable anionic Pt(0) complexes were successfully stabilized through the leveraging of the electron-accepting ability of boron compounds. This use of a diphosphine-borane ligand DPB allows for straightforward access to anionic Pt⁰ complexes, with [(DPB)PtX]⁻ complexes being both isolated and fully characterized. These demonstrate unique examples of square-planar Pt⁰ complexes, and. were substantiated by way of X-ray diffraction analyses and X-ray photoelectron spectroscopy, as well as and DFT calculations.

Anionic M⁰ complexes (M=Group 10 metals) are significant species but are difficult to pin down, but have been established and are recognized as key intermediates in many catalytic cross-couplings. Regardless, the amount and variety of such complexes to be characterized and/or isolated is still limited, with really only the anionic Ni⁰ and Pd⁰ species having been authenticated.

“The results of this research not only enable us to elucidate the properties and functions of highly active chemical species but also provide new guidelines for their creation. It is expected to lead to the development of innovative catalytic reactions mediated by these chemical species.”Hajime Kameo