Conformational dynamics of Cu(I) complexes of tripodal ligands: Steric control of molecular motion

Jing Zhang, Kam Siu, Chin H. Lin, James W. Canary

Research output: Contribution to journalArticle

Abstract

The dynamics of molecular conformational changes for Cu(I) complexes of two tripodal ligands were studied. Variable-temperature NMR and circular dichroism in combination with two-dimensional NMR experiments were employed to determine the structural and energetic details of a dynamic process in which one of three arms dissociates from coordination to Cu(I). Dissociation was triggered by addition of a strongly coordinating anion (SCN-). One-electron oxidation to the Cu(II) complex returned coordination of all three ligand arms. The observed phenomena were dependent upon steric crowding; addition of a single methyl group to one arm resulted in marked differences in behavior. The CuSCN and CuPF6 complexes of tris(2-quinolylmethyl)amine (TQA) and the CuPF6 complex of 1-(quinolin-2-yl)-N,N-bis(quinolin-2-ylmethyl) ethanamine (MeTQA) did not give any evidence for differences in coordination over the temperature range 0-35 °C, while CuI(MeTQA)NCS demonstrated marked differences in NMR but not CD spectra over this temperature range. In the latter complex, two diastereotopic arms displace each other with a transition energy of 14.0 kcal mol-1. The structure of the arm-dissociated complex contains a higher degree of stereochemical complexity than the tetradentate complexes.

Original languageEnglish (US)
Pages (from-to)1147-1151
Number of pages5
JournalNew Journal of Chemistry
Volume29
Issue number9
DOIs
StatePublished - Sep 2005

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Materials Chemistry

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