Precursor Catenand Complexes: Synthesis, Structure, and Electrochemistry of Bis(2,6-di-iminopyridyl) Complexes of Nickel(II). The Single-crystal X-Ray Structure of 42>2

Article abstract of DOI:10.1039/DT9890000965

Reaction of Ni(BF4)2*6H2O with 2 equivalents of the tridentate 2,6-di-iminopyridyl ligands (L) < L= NC5H3(CMe=NR)-2,6 ( R=Et, Ph, CH2Ph, or CH2CH2CH2Ph)> in EtOH-CH2Cl2 affords the octahedral complexes 2>2.The complex 42>2 ( R=CH2CH2CH2Ph) crystallises in the triclinic space group P1, with a=11.640(4), b=12.8846(27), c=18.906(6) Angstroem, α=90.270(22), β=95.226(28), γ=112.098(24) deg, and Z=2.The single-crystal X-ray structure shows a distorted octahedral geometry around nickel(II) with four imine N-donors occupying equatorial sites and two shorter axial bonds to pyridyl N-donors .The four propylphenyl groups of L extend past the inner co-ordination sphere of the metal ion into positions which could potentially be linked together to form octahedral catenand species.Cyclic voltammetry of 2 (R=CH2Ph or CH2CH2CH2Ph) in MeCN at platinum electrodes shows for each complex two reversible one-electron reductions at (1)E_1/2=-1.56 and -1.53 V and (2)E_1/2=-1.89 and -1.87 V respectively, and one-electron oxidation process at E_1/2= +1.22 and +1.12 V vs. ferrocene-ferrocenium respectively.The quantitative electrogeneration of the corresponding mono-reduced and -oxidised species has been accomplished and assigned by e.s.r. spectroscopy to the formation of nickel-(I) and -(III) complexes respectively.

Full text of DOI:10.1039/DT9890000965

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