Alkane Coordination Selectivity in Hydrocarbon Activation by [Tp‘Rh(CNneopentyl)]: The Role of Alkane Complexes

The competitive activation of C−H bonds of linear, cyclic, and branched hydrocarbons using the coordinatively unsaturated 16-electron [Tp‘RhL] reactive fragment have been studied (Tp‘ = tris-(3,5-dimethylpyrazolyl)borate; L = CNCH2CMe3). Activation of the hydrocarbons leads to the formation of Tp‘Rh(L)(R)(H) alkyl complexes, which were converted to the stable chlorides immediately following the activation of the bonds via photolysis of Tp‘Rh(L)(PhNCNCH2CMe3) in the solvent mixture. The products were analyzed by 1H NMR spectroscopy. The experiments described provide relative rates for the coordination of primary and secondary C−H bonds to the Rh metal center, indicating a 1.5× preference for the latter.