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Issue 10, 2014
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Homo- and heteropolymetallic 3-(2-pyridyl)pyrazolate manganese and rhenium complexes

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fac-[MBr(CO)3(pypzH)] (M = Mn, Re; pypzH = (3-(2-pyridyl)pyrazole) complexes are prepared from fac-[MBr(CO)3(NCMe)2] and pypzH. The result of their deprotonation depends on the metallic substrate: the rhenium complex affords cleanly the bimetallic compound [fac-{Re(CO)32-pypz)}]22-pypz = μ2-3-(2-pyridyl-κ1N)pyrazolate-2κ1N), which was crystallographically characterized, whereas a similar manganese complex was not detected. When two equivalents of pyridylpyrazolate are used, polymetallic species [fac-M(CO)32-pypz)(μ3-pypz)M′] (μ3-pypz = μ3-3-(2-pyridyl-κ1N)pyrazolate-1κ2N,N:2κ1N:; M = Mn, M′ = Li, Na, K; M = Re, M′ = Na) are obtained. The crystal structures of the manganese carbonylate complexes were determined. The lithium complex is a monomer containing one manganese and one lithium atom, whereas the sodium and potassium complexes are dimers and reveal an unprecedented coordination mode for the bridging 3-(2-pyridyl)pyrazolate ligand, where the nitrogen of the pyridyl fragment and the nitrogen-1 of pyrazolate are chelated to manganese atoms, and each nitrogen-2 of pyrazolate is coordinated to two alkaline atoms. The polymetallic carbonylate complexes are unstable in solution and evolve spontaneously to [fac-{Re(CO)32-pypz)}]2 or to the trimetallic paramagnetic species [MnII2-pypz)2{fac-{MnI(CO)32-pypz)}2}]. The related complex cis-[MnCl2(pypzH)2] was also synthesized and structurally characterized. The electrochemical behavior of the new homo- and heteropolymetallic 3-(2-pyridyl)pyrazolate complexes has been studied and details of their redox properties are reported.

Graphical abstract: Homo- and heteropolymetallic 3-(2-pyridyl)pyrazolate manganese and rhenium complexes

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The article was received on 06 Dec 2013, accepted on 24 Dec 2013 and first published on 22 Jan 2014

Article type: Paper
DOI: 10.1039/C3DT53439A
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Citation: Dalton Trans., 2014,43, 4009-4020
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    Homo- and heteropolymetallic 3-(2-pyridyl)pyrazolate manganese and rhenium complexes

    M. Arroyo, P. Gómez-Iglesias, N. Antón, R. García-Rodríguez, E. C. B. A. Alegria, A. J. L. Pombeiro, D. Miguel and F. Villafañe, Dalton Trans., 2014, 43, 4009
    DOI: 10.1039/C3DT53439A

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