A Series of Crystallographically Characterized Linear and Branched σ-Alkane Complexes of Rhodium: From Propane to 3-Methylpentane
Alexander J. Bukvic, Arron L. Burnage, Graham J. Tizzard, Antonio J. Martı́nez-Martı́nez, Alasdair I. McKay, Nicholas H. Rees, Bengt E. Tegner, Tobias Krämer, Heather Fish, Mark R. Warren, Simon J. Coles, Stuart A. Macgregor, Andrew S. Weller
Abstract
anions. For the propane complex, a small alkane binding energy, driven in part by a lack of stabilizing short contacts with the surrounding anions, correlates with the fleeting stability of this species. 2-Methylbutane forms more short contacts within the binding pocket, and as a result the complex is considerably more stable. However, the complex of the larger 3-methylpentane ligand shows lower stability. Empirically, there therefore appears to be an optimal fit between the size and shape of the alkane and overall stability. Such observations are related to guest/host interactions in solution supramolecular chemistry and the holistic role of 1°, 2°, and 3° environments in metalloenzymes.