MicroED characterization of a robust cationic σ-alkane complex stabilized by the [B(3,5-(SF5)2C6H3)4]- anion, via on-grid solid/gas single-crystal to single-crystal reactivity

Microcrystalline (similar to 1 mu m) [Rh(Cy2PCH2CH2PCy2)(norbornadiene)][S-BAr4F], [S-BAr4F] = [B(3,5-(SF5)(2)C6H3)(4)](-), reacts with H-2 in a single-crystal to single-crystal transformation to form the sigma-alkane complex [Rh(Cy2PCH2CH2PCy2)(norbornane)][S-BAr4F], for which the structure was determined by microcrystal Electron Diffraction (microED), to 0.95 angstrom resolution, via an on-grid hydrogenation, and a complementary single-crystal X-ray diffraction study on larger, but challenging to isolate, crystals. Comparison with the [BAr4F](-) analogue [Ar-F = 3,5-(CF3)(2)(C6H3)] shows that the [S-BAr4F](-) anion makes the sigma-alkane complex robust towards decomposition both thermally and when suspended in pentane. Subsequent reactivity with dissolved ethene in a pentane slurry, forms [Rh(Cy2PCH2CH2PCy2)(ethene)(2)][S-BAr4F], and the catalytic dimerisation/isomerisation of ethene to 2-butenes. The increased stability of [S-BAr4F](-) salts is identified as being due to increased non-covalent interactions in the lattice, resulting in a solid-state molecular organometallic material with desirable stability characteristics.

Automated summary

The study found that the [S-BAr4F](-) anion enhances the stability of the sigma-alkane complex [Rh(Cy2PCH2CH2PCy2)(norbornane)][S-BAr4F] both thermally and when suspended in pentane. Furthermore, the increased stability of [S-BAr4F](-) salts is mainly attributed to enhanced non-covalent interactions in the lattice.