MicroED characterization of a robust cationic σ-alkane complex stabilized by the [B(3,5-(SF)CH)] anion, on-grid solid/gas single-crystal to single-crystal reactivity.

Microcrystalline (∼1 μm) [Rh(CyPCHCHPCy)(norbornadiene)][S-BAr], [S-BAr] = [B(3,5-(SF)CH)], reacts with H in a single-crystal to single-crystal transformation to form the σ-alkane complex [Rh(CyPCHCHPCy)(norbornane)][S-BAr], for which the structure was determined by microcrystal Electron Diffraction (microED), to 0.95 Å resolution, an on-grid hydrogenation, and a complementary single-crystal X-ray diffraction study on larger, but challenging to isolate, crystals. Comparison with the [BAr] analogue [Ar = 3,5-(CF)(CH)] shows that the [S-BAr] anion makes the σ-alkane complex robust towards decomposition both thermally and when suspended in pentane. Subsequent reactivity with dissolved ethene in a pentane slurry, forms [Rh(CyPCHCHPCy)(ethene)][S-BAr], and the catalytic dimerisation/isomerisation of ethene to 2-butenes. The increased stability of [S-BAr] 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.