Homo- and heteropolymetallic 3-(2-pyridyl)pyrazolate manganese and rhenium complexesCCDC 873520, 974910, 873521, 974911, 873522 and 873523. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c3dt53439a

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) 3 (μ 2 -pypz)}] 2 (μ 2 -pypz = μ 2 -3-(2-pyridyl-κ 1 N )pyrazolate-2κ 1 N ), which was crystallographically characterized, whereas a similar manganese complex was not detected. When two equivalents of pyridylpyrazolate are used, polymetallic species [ fac -M(CO) 3 (μ 2 -pypz)(μ 3 -pypz)M′] (μ 3 -pypz = μ 3 -3-(2-pyridyl-κ 1 N )pyrazolate-1κ 2 N , N :2κ 1 N :; 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) 3 (μ 2 -pypz)}] 2 or to the trimetallic paramagnetic species [Mn II (μ 2 -pypz) 2 { fac -{Mn I (CO) 3 (μ 2 -pypz)} 2 }]. The related complex cis -[MnCl 2 (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. Heteropolymetallic complexes with pyridylpyrazolates bridging Mn and Na or K are tetrametallic and contain bridging pyridylpyrazolates with an unprecedented coordination mode, whereas the Mn/Li complex is bimetallic.