Rationalizing the structural variability of the exocyclic amino groups in nucleobases and their metal complexes: Cytosine and adenine

The exocyclic amino groups of cytosine and adenine nucleobases are normally almost flat, with the N atoms essentially sp2 hybridized and the lone pair largely delocalized into the heterocyclic rings. However, a change to marked pyramidality of the amino group (N then sp3 hybridized, lone pair essentially localized at N) occurs during i) involvement of an amino proton in strong hydrogen bonding donor conditions or ii) with monofunctional metal coordination following removal of one of the two protons. Hybridization and structure of exocyclic amino groups of cytosine and adenine nucleobases can shift from sp2 to sp3 (see graphic) if an amino proton acts as a donor in a strong hydrogen-bonding interaction or if it is replaced by a monofunctionally bonded metal ion. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.We gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft (DFG), the National Research School Combination-Catalysis (NRSC-C), the Netherlands Organization for Scientific Research (NWO-CW and NWO-EW), and the Spanish Ministerio de Economía y Competitividad (“Ramón y Cajal” program (P.J.S.M.) and CTQ2011-27593).Peer Reviewe

Rationalizing the structural variability of the exocyclic amino groups in nucleobases and their metal complexes: Cytosine and adenine

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