The Center for Enabling New Technologies Through Catalysis (CENTC) has been encouraging cutting edge research on the activation and transformation of strong bonds (C-H, C-C, etc.) since its inception in 2007. With scientists working collaboratively across more than a dozen top research universities and national labs, the impact of the CENTC network has reached well beyond its core group of scientists to include the research and intellectual creativity of many alumni, including those conducting research at primarily undergraduate institutions like The College of New Jersey. Transition metal complexes have been shown to efficiently catalyze the selective functionalization of aryl C-H bonds. In this context, aryl substituents that can act as �directing� groups have afforded selectivity for ortho C-H bonds vs. those in the meta and para positions in some cases. Contrasting results have been shown with the iridium fragment (tBuPCP)Ir (tBuPCP = {?3-2,6-bis[(di-tert-butylphosphino)methyl]phenyl}). With this complex, little or no thermodynamic preference for the ortho C-H addition products of substituted benzenes is found. In addition, bulky ortho substituents inhibit the rates of C-H addition and elimination. Our current research is focused on alkyl-substituted pyridines; in these substrates, there is a strong preference for N-coordination to the metal center over oxidative addition of an aryl C-H bond, potentially limiting the efficacy of transition metal-mediated C-H activation reactions. Strategic selection of alkyl substituents has illuminated the competing effects of coordinating groups vs. the constraints of geometry in the transition state for addition/elimination. Results for a range of related substrates will be discussed.

Selectivity in C-H bond activation of substituted pyridines: Overcoming the influence of a strongly coordinating arene heteroatom

247th National Meeting (2014)

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