Recent years have witnessed considerable progress in chemical concepts and practices directed to adopt more efficient and sustainable technologies, among which of particular interest is mechanochemistry that utilizes mechanical energy to induce chemical reactions. Mechanochemistry has reached high significance in the creation of advanced materials (alloys, ceramics, nanocomposites, etc.), but in the field of small molecule synthesis, in particular, the synthesis of organometallic compounds its potential remains largely untapped [1]. In turn, direct cyclometalation is a versatile and popular method that gives simple and straightforward access to different organometallic species. In this work, we have explored the opportunities and prospects of mechanochemical tools in the synthesis of pincer-type complexes featuring thiophosphoryl or phosphoryl and thiocarbamate pendant arms. The former were used either as seemingly spectator donor moieties in symmetrical bis(thiocarbamate) pincer systems or active coordination sites in their hybrid monothiocarbamate analogs (Fig. 1). The peculiarities of cyclopalladation of the ligands obtained were studied both in solution and under solvent-free conditions (upon grinding or milling). The mechanochemical approach has been shown to offer such advantages as the absence of any auxiliary and significant rate and yield enhancement and can be extended to wider metal-organic and organometallic pincer chemistry.

This work was supported by the Russian Science Foundation, project no. 22-13-00267.

[1] Aleksanyan, D. V.; Kozlov, V. A. Mendeleev Commun. 2023, 33, 287–301.