Mononuclear iron(ii) complexes containing a tripodal and macrocyclic nitrogen ligand: synthesis, reactivity and application in cyclohexane oxidation catalysis12. Issue 43 (22nd October 2018)

• Record Type: Journal Article
• Authors: Ayad, Massinisa; Klein Gebbink, Robertus J. M.; Le Mest, Yves; Schollhammer, Philippe; Le Poul, Nicolas; Pétillon, François Y.; Mandon, Dominique
• Is Part Of: Dalton transactions. Volume 47:Issue 43(2018)
• Page Start: 15596
• Page End: 15612
• Publication Date: 2018-10-22
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c8dt02952k
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The macrocyclic design of a TPA-based ligand enhances the catalytic properties of the resulting Fe(ii ) complexes for cyclohexane oxidation. Abstract : Two novel tripodal ligandsL 1 andL 2 based on a tris(methylpyridyl)amine (TPA) motif have been prepared and reacted with two different iron(ii ) salts. The ligandL 1 contains a bis(amino-phenyl)-TPA group whereas the macrocyclic ligandL 2 displays two different coordinating cores, namely TPA and pyridine–dicarboxamide. The resulting mononuclear complexes1–4 have been characterized in the solid state and in solution by spectroscopic and electrochemical methods. All complexes are high spin and mainly pentacoordinated. X-ray diffraction analyses of the crystals of complexes2 and3 demonstrate that the coordination sphere of the iron(ii ) centre adopts either a distorted bipyramidal–trigonal or square pyramidal geometry. In the absence of an exogenous substrate, oxidation of complex2 by H2 O2 induces an intramolecular aromatic hydroxylation, as shown by the X-ray structure of the resulting dinuclear complex2′ . Catalytic studies in the presence of a substrate (cyclohexane) show that the reaction process is strongly impacted by the macrocyclic topology of the ligand and the nature of the counter-ion.