Solid-state molecular organometallic chemistry. Single-crystal to single-crystal reactivity and catalysis with light hydrocarbon substrates† †Electronic supplementary information (ESI) available: Full details of experimental details, spectroscopic and other analytical data, X-ray crystallography, catalytic conditions, and computational studies. CCDC 1539832–1539836. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc01491k

Single-crystal to single-crystal solid/gas reactivity and catalysis starting from the precursor sigma-alkane complex [Rh(Cy2PCH2CH2PCy2)(h h-NBA)][BAr4] (NBA 1⁄4 norbornane; Ar 1⁄4 3,5-(CF3)2C6H3) is reported. By adding ethene, propene and 1-butene to this precursor in solid/gas reactions the resulting alkene complexes [Rh(Cy2PCH2CH2PCy2)(alkene)x][BAr F 4] are formed. The ethene (x 1⁄4 2) complex, [Rh(Cy2PCH2CH2PCy2)(ethene)2][BAr F 4]-Oct, has been characterized in the solid-state (single-crystal X-ray diffraction) and by solution and solid-state NMR spectroscopy. Rapid, low temperature recrystallization using solution methods results in a different crystalline modification, [Rh(Cy2PCH2CH2PCy2)(ethene)2][BAr F 4]-Hex, that has a hexagonal microporous structure (P6322). The propene complex (x 1⁄4 1) [Rh(Cy2PCH2CH2PCy2)(propene)][BAr4] is characterized as having a p-bound alkene with a supporting g-agostic Rh/H3C interaction at low temperature by single-crystal X-ray diffraction, variable temperature solution and solid-state NMR spectroscopy, as well as periodic density functional theory (DFT) calculations. A fluxional process occurs in both the solid-state and solution that is proposed to proceed via a tautomeric allyl-hydride. Gas/solid catalytic isomerization of d3-propene, H2C]CHCD3, using [Rh(Cy2PCH2CH2PCy2)(h h-NBA)][BAr4] scrambles the D-label into all possible positions of the propene, as shown by isotopic perturbation of equilibrium measurements for the agostic interaction. Periodic DFT calculations show a low barrier to H/D exchange (10.9 kcal mol , PBE-D3 level), and GIPAW chemical shift calculations guide the assignment of the experimental data. When synthesized using solution routes a bis-propene complex, [Rh(Cy2PCH2CH2PCy2)(propene)2][BAr F 4], is formed. [Rh(Cy2PCH2CH2PCy2)(butene)][BAr F 4] (x 1⁄4 1) is characterized as having 2-butene bound as the cis-isomer and a single Rh/H3C agostic interaction. In the solid-state two low-energy fluxional processes are proposed. The first is a simple libration of the 2-butene that exchanges the agostic interaction, and the second is a butene isomerization process that proceeds via an allyl-hydride intermediate with a low computed barrier of 14.5 kcal mol . [Rh(Cy2PCH2CH2PCy2)(h h-NBA)][BAr4] and the polymorphs of [Rh(Cy2PCH2CH2PCy2)(ethene)2][BAr F 4] are shown to be effective in solid-state molecular organometallic catalysis (SMOM-Cat) for the isomerization of 1-butene to a mixture of cisand trans-2-butene at 298 K and 1 atm, and studies suggest that catalysis is likely dominated by surfaceactive species. [Rh(Cy2PCH2CH2PCy2)(h h-NBA)][BAr4] is also shown to catalyze the transfer dehydrogenation of butane to 2-butene at 298 K using ethene as the sacrificial acceptor.