Supramolecular interactions in mononuclear iron(III) complex derived from a diamide ligand: Spectroscopic and electrochemical properties

Abstract

The diamide ligand, 2,6-bis[(N-phenyl)amido]-4-methylphenol (HL), has been used to synthesize a mononuclear iron(III) complex [Fe(L)₃]·DMF and characterized by elemental analyses, IR, UV–vis spectroscopy, cyclic voltammetry and finally by X–ray crystallography. X-ray diffraction analysis reveals that the complex crystallizes<span style="mso-bidi-font-weight:bold"> in the triclinic space group <i style="mso-bidi-font-style:normal">P-1(2)<span style="color:black;mso-bidi-font-style:italic"> </span></i><span style="color:black;mso-bidi-font-style:italic">with <i>a</i> = 12.4923(15) Å, <i>b</i>= 13.5095(16), <i>c </i>= 19.296(2) Å, <i style="mso-bidi-font-style:normal"><span style="color:black;mso-ansi-language:SV" lang="SV">α </span></i>= <i><span style="color:black;mso-ansi-language:SV" lang="SV">β</span></i><i style="mso-bidi-font-style:normal"> </i>= <span style="mso-bidi-font-style:italic">86.451(2)°, <i style="mso-bidi-font-style:normal"><span style="color:black;mso-ansi-language:SV" lang="SV">γ</span></i><span style="color:black;mso-bidi-font-style:italic" lang="EN-GB"> = 66.5850(10)°, <i>V</i> = 2980.1(6) ų and <i style="mso-bidi-font-style:normal">Z</i> = 2 with the central iron(III) ion in distorted octahedral geometry. The complex shows extensive intra- and intermolecular hydrogen bonding between each molecular units as well as solvent molecules giving rise to a two dimensional assembly. It also exhibits <span style="color:black; mso-ansi-language:EN-IN;mso-fareast-language:EN-IN">intermolecular π–π<span style="color:black;mso-ansi-language:EN-IN;mso-fareast-language:EN-IN"> interaction between the aromatic rings with centroid distances of around 3.55 Å. In cyclic voltammetric studies, the iron(III) complex exhibits one quasi-reversible reduction at <i style="mso-bidi-font-style:normal">E</i>_1/2= +0.046 V <span style="mso-bidi-font-style:italic">versus Ag/AgCl <span style="color:black;mso-ansi-language:EN-IN">(Δ<i style="mso-bidi-font-style:normal"><span style="color:black;mso-ansi-language:EN-IN">E</span></i>_{<span style="color:black;mso-ansi-language:EN-IN">p</span>}<span style="color:black;mso-ansi-language:EN-IN"> = 0.092 V) due to a metal-centreed Fe^III/Fe^II reduction.<span style="color:black;mso-ansi-language:EN-IN;mso-fareast-language:EN-IN">

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