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Issue 40, 2017
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Isolation and characterization of a tetranuclear Pt–Fe⋯Fe–Pt intermediate en route to the trinuclear Pt–Fe–Pt cluster

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Abstract

An intermediate compound, [{PtFe(piam)2(NH3)2(OCH3)}2(μ-OCH3)2](ClO4)2 (1, piam = pivalamidate), in the synthetic process to form [Pt2Fe(piam)4(NH3)4](ClO4)3 (2) by mixing cis-[Pt(piam)2(NH3)2]·2H2O and iron sources was successfully isolated and characterized by single-crystal X-ray analysis. In 1, the platinum and iron atoms are bridged by two piam ligands to afford a dinuclear Pt–Fe structure and are further linked to each other by methoxide bridges at the equatorial positions of iron atoms to form a tetranuclear Pt–Fe⋯Fe–Pt complex. The Pt–Fe distances in 1 are 3.0010(16) and 2.9883(17) Å, which are significantly longer than those in 2 (2.5566(15) and 2.5718(15) Å). X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and magnetic susceptibility measurements revealed that the oxidation states are Pt(+2)–Fe(+3)⋯Fe(+3)–Pt(+2) (1) and Pt(+2)–Fe(+3)–Pt(+2) (2) with high-spin (S = 5/2) configurations in iron atoms. The magnetic susceptibility of 1 has a χT value of 5.83 cm3 mol−1 K per Pt(+2)–Fe(+3)⋯Fe(+3)–Pt(+2) unit at 300 K, which decreases down to 0.04 cm3 mol−1 K at 7 K due to antiferromagnetic coupling (J = −28 cm−1) of the two Fe(+3) centers. Compound 2 maintains its trinuclear structure in MeCN, exhibiting reversible one-electron reduction and oxidation, Pt(+2)–Fe(+2)–Pt(+2) ↔ Pt(+2)–Fe(+3)–Pt(+2), at E1/2 = −0.19 V (vs. Fc/Fc+). However, in MeOH, compound 2 is decomposed into a dinuclear structure of Pt–Fe involving an equilibrium between 1 and 2.

Graphical abstract: Isolation and characterization of a tetranuclear Pt–Fe⋯Fe–Pt intermediate en route to the trinuclear Pt–Fe–Pt cluster

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Publication details

The article was received on 16 Jul 2017, accepted on 21 Sep 2017 and first published on 21 Sep 2017


Article type: Paper
DOI: 10.1039/C7DT02583A
Citation: Dalton Trans., 2017,46, 14012-14020
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    Isolation and characterization of a tetranuclear Pt–Fe⋯Fe–Pt intermediate en route to the trinuclear Pt–Fe–Pt cluster

    K. Uemura and M. Taoka, Dalton Trans., 2017, 46, 14012
    DOI: 10.1039/C7DT02583A

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