Synthesis, structure, and characterization of tris(1-ethyl-4-isopropyl-imidazolyl-қN)phosphine nickel(II) complexes

摘要: Abstract In this work we report the synthesis of five new nickel(II) complexes all coordinated to tripodal ligand tris(1-ethyl-4-iPr-imidazolyl)phosphine (T1Et4iPrIP). They are [Ni(T1Et4iPrIP)(CH3CN)2(OTf)](OTf) (1), [Ni(T1Et4iPrIP)(OTf)2] (2), [Ni(T1Et4iPrIP)(H2O)(OTf)](OTf) (3), [Ni(T1Et4iPrIP)Cl](OTf) (4), and [Ni(T1Et4iPrIP)Cl2] (5). The serve as bioinorganic structural model for histidine-coordinated nickel proteins. X-ray structures have been determine which feature coordination numbers 4–6. We investigated spectroscopic interconversions these compound in dichloromethane solution demonstrate interconversion between 1 3 via 2 conversion 4. Complex 5 can be spectroscopically converted cation 4 by dissolving it dichloromethane. Fits variable temperature magnetic susceptibility data yielded following parameters: g = 1.944, D = −0.327 cm−1, E/D = 3.706 1; g = 2.280, D = −0.365 cm−1, E/D = 22.178 2; g = 2.000, D = −7.402 cm−1, E/D = −0.272 3; g = 2.176, D = −0.128 cm−1, E/D = −0.783 4; g = 2.258, D = 14.288 cm−1, E/D = 0.095 5. DFT structure optimizations afforded HOMO LUMO energies indicating that complex is most stable.