154385-47-4Relevant articles and documents
Structural and functional models for the dicopper site in hemocyanin. Dioxygen binding by copper complexes of tris(1-R-4-R′-imidazolyl-kN)phosphines
Lynch, Will E.,Kurtz Jr., Donald M.,Wang, Shengke,Scott, Robert A.
, p. 11030 - 11038 (2007/10/02)
Complexes of the type [CuI(T1Et4RIP)]X (T1Et4RIP = tris(1-ethyl-4-R-imidazolyl)phosphine (R = methyl (Me), isopropyl (iPr)); X = PF6, ClO4, CF3SO3), in which T1Et4RIP functions as a tridentate nitrogen donor ligand, were prepared by Lewis acid-base reactions between [CuICH3CN)4]X and T1E14RIP in dry, degassed solvents. The colorless acetonitrile adducts, [CuI(T1Et4RIP)(CH3CN)]X, were obtained by crystallization from acetontrile. The complex with R = iPr and X = PF6 crystallizes in the space group I213 with a = b = c = 18.912(2) ? and Z = 8. The refinement converged with a final R (Rw) value of 0.075 (0.098) for 988 reflections with F > 3σ(Fo). The CuI is coordinated in a trigonally distorted tetrahedral fashion to three imidazolyl nitrogen atoms at 2.08 ? and one acetonitrile nitrogen atom at 1.90 ? . Exposure of dry solutions of these CuI complexes to O2 below -60 °C resulted in an isolable purple species with spectroscopic and magnetic properties characteristic of (μ-η2:η2-peroxo)-dicopper(II) complexes. The representative complex analyzing for {[Cu(T1Et4MeIP)]2(O2)}(PF6)2 has the following approximate values: diamagnetic; UV-vis, 338 nm (∈ = 19 000 M-1 cm-1), 521 nm (∈ = 1000 M-1 cm-1); υ-(O-O), 740 cm-1. The Cu X-ray absorption fine structure spectrum of this complex with X = ClO4 was best fit with a Cu scatterer at 3.48 ? , two O (or N) scatterers at 1.94 ?, and two sets of N (or O) scatterers: two at 2.05 ? and one at 2.30 ?. These spectroscopic, magnetic, and structural properties are characteristic of (μ-η2:η2-peroxo)dicopper(II) complexes having a planar Cu2O2 core and terminal nitrogen donor ligands, including the dicopper site in oxyhemocyanin. The [CuI(T1Et4RIP)(CH3CN)]X complexes with R = iPr react with O2 at - 78 °C to produce dioxygen adducts with spectroscopic and magnetic properties very similar to those listed above for R = Me. The complexes with R = iPr, upon repeated thermal cycling between -78 and ≈-20 °C in methanol, exhibit reversible binding of dioxygen. This process can be readily monitored by the characteristic visible absorption spectrum of the dioxygen adduct. Thus, copper complexes of tris(imidazolyl)phosphines with 1,4-disubstituted imidazolyl groups have been successfully used to model spectroscopic, magnetic, structural, and functional properties of the dicopper site in hemocyanin.
