title: Selective C-H Activation at a Molecular Rhodium Sigma-Alkane Complex by Solid/Gas Single-Crystal to Single-Crystal H/D Exchange.
abstract: The controlled catalytic functionalization of alkanes via the activation of C-H bonds is a significant challenge. Although C-H activation by transition metal catalysts is often suggested to operate via intermediate σ-alkane complexes, such transient species are difficult to observe due to their instability in solution. This instability may be controlled by use of solid/gas synthetic techniques that enable the isolation of single-crystals of well-defined σ-alkane complexes. Here we show that, using this unique platform, selective alkane C-H activation occurs, as probed by H/D exchange using D2, and that five different isotopomers/isotopologues of the σ-alkane complex result, as characterized by single-crystal neutron diffraction studies for three examples. Low-energy fluxional processes associated with the σ-alkane ligand are identified using variable-temperature X-ray diffraction, solid-state NMR spectroscopy, and periodic DFT calculations. These observations connect σ-alkane complexes with their C-H activated products, and demonstrate that alkane-ligand mobility, and selective C-H activation, are possible when these processes occur in the constrained environment of the solid-state.
authors.affiliation: Department of Chemistry, Mansfield Road, University of Oxford , Oxford OX1 3TA, U.K.
authors.forename: F Mark
authors.initials: FM
authors.lastname: Chadwick
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, U.K.
authors.forename: Tobias
authors.initials: T
authors.lastname: Krämer
authors.affiliation: Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt , Alarich-Weiss-Strasse 8, D-64287 Darmstadt, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Gutmann
authors.affiliation: Department of Chemistry, Mansfield Road, University of Oxford , Oxford OX1 3TA, U.K.
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Rees
authors.affiliation: Department of Chemistry, Mansfield Road, University of Oxford , Oxford OX1 3TA, U.K.
authors.forename: Amber L
authors.initials: AL
authors.lastname: Thompson
authors.affiliation: Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organization , Locked Bag 2001 Kirrawee D.C., New South Wales 2232, Australia.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Edwards
authors.affiliation: Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt , Alarich-Weiss-Strasse 8, D-64287 Darmstadt, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Buntkowsky
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, U.K.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Macgregor
authors.affiliation: Department of Chemistry, Mansfield Road, University of Oxford , Oxford OX1 3TA, U.K.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Weller