The inorganic and bioinorganic chemistry of copper thioether complexes

Recent data regarding the cofactor and cofactor binding environment of ETR1, an ethylene receptor protein from Arabidopsis thaliana provided a foundation for rational design of synthetic, biologically relevant models. Herein is reported the synthesis and characterization of two novel series of inorganic Cu(I) complexes designed to highlight the difference between amine and sulfur ligation to Cu as it influences a bound ethylene moiety.; Vibrational characterization reveals that amine ligation to copper promotes stronger backbonding in π acid ligands like ethylene, cyanide, acetonitrile and carbon monoxide. The signature stretching frequency of each complex in the amine series was lower in energy compared to the analogous complex in the thioether series. These data imply that the σ donor properties of nitrogen promoted better donation of metal d orbital density onto the unsaturated moiety. The vibrational spectroscopy of the ethylene complexes was complicated by the coincident motion of CH with CC. This issue was addressed through characterization of the deuterated ethylene analog in which CH and CC motions are separated. Density functional analysis agreed with experimental results and confirmed the predominance of backbonding in the series of amine ligated copper complexes.; Structural characterization of novel Cu(I) complexes was accomplished using EXAFS and X-ray crystallographic analyses. Crystallographic structures of Cu(I) thioether and Cu(I) amine complexes are reported. EXAFS data were collected on a thioether copper ethylene complex and a thioether copper carbonyl complex. These data showed a weakly bound gaseous moiety.; Solution NMR studies show thioether Cu(I) ethylene complexes are labile in solution at room temperature while amine ligated Cu(I) ethylene complexes do not exchange down to −18°C, Solid state NMR was proven to be effective in characterizing Cu(I) ethylene complexes. The first solid state NMR spectrum and chemical shift anisotropy of an ethylene complex are reported. Data on other complexes are presented for comparison.