• Chadwick, F. Mark
• Rees, Nicholas H.
• Buntkowsky, Gerd
• Weller, Andrew S.
• Macgregor, Stuart Alan
• Krämer, Tobias
• Thompson, Amber L.
• Gutmann, Torsten
• Edwards, Alison J.

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.

Topics

• impedance spectroscopy
• mobility
• x-ray diffraction
• Rhodium
• neutron diffraction
• density functional theory
• activation
• Nuclear Magnetic Resonance spectroscopy
• functionalization
• alkane