Synthesis, Structure, and Properties of μ-Oxo-Bridged FeIII2 and Heterometallic Azide-Bridged FeIII2CuII Complexes of a Picolinamide In-Plane Ligand

✍ Scribed by José M. Domínguez-Vera; José Suárez-Varela; Ikram Ben Maimoun; Enrique Colacio

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 132 KB
• Volume: 2005
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.200400911

✦ Synopsis

Abstract

A new μ‐oxodiiron(III) complex [{Fe^III^(bpc)(H~2~O)}~2~O] (1) with the bis(picolinamide) N~4~ in‐plane ligand 4,5‐dichloro‐1,2‐bis(pyridine‐2‐carboxamido)benzene (H~2~bpc) has been prepared by the reaction of [Fe(bpc)Cl(H~2~O)] with a stoichiometric amount of cyanide, and characterized by X‐ray structure analysis. The IR and UV/Vis spectroscopic results match well with those expected from the respective previously established spectro‐structure correlation. Likewise, the temperature dependence of the magnetic susceptibility shows the existence of a strong antiferromagnetic coupling between the iron(III) centers [S = 5/2; with J = –108.10(3) cm^–1^] that is consistent with the radial and angular overlap Weihe–Güdel model in μ‐oxodiiron(III) complexes. Two heterometallic Fe^III^‐Cu^II^Fe^III^ (2) and Fe^III^Ni^II^Fe^III^ (3) complexes have been prepared from the reaction between [Fe^III^(bpc)(N~3~)~2~] and [Cu(meso‐CTH)]^2+^ or [Ni(meso‐CTH)]^2+^ (CTH = 5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane), respectively. The structure of 2 consists of heterometallic Fe^III^Cu^II^Fe^III^ units formed by the simultaneous coordination of two [Fe^III^(bpc)(N~3~)~2~] units to the central [Cu(meso‐CTH)] units through a μ~1,3~‐azide bridging ligand. However, the structure of 3 contains isolated [Fe^III^(bpc)(N~3~)~2~]^–^ and [Ni(meso‐CTH)]^2+^ ions. The treatment of the magnetic data of 2 revealed the existence of a small ferromagnetic interaction between Fe^III^ and Cu^II^ metal ions, with J~FeCu~ = 3.24(7) cm^–1^. The existence of 2 opens up the possibility of obtaining, in a rational manner, azide‐bridged heterometallic complexes starting from the block precursor [Fe^III^(bpc)(N~3~)~2~]^–^. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)