Cobaloximes with Pyrazine and Their Dimetallic Complexes

Mono‐ and dinuclear cobaloximes with inorganic anions and pyrazine (Pz) as a base/bridging ligand were synthesized and characterized by 1 H, 13 C, UV/Vis and IR spectroscopy and X‐ray structure analysis. Mononuclear complexes XCo(dioxime) 2 Pz were used as precursors for building homo‐ and heterodimetallic complexes. The X‐ray crystal structures of ClCo(dmgH) 2 Pz, ClCo(dpgH) 2 Pz, [Co(dpgH) 2 (NO 2 ) 2 ]Na, and [Co(dmgH) 2 (NO 2 ) 2 ] 2 [Ag] 2 · H 2 O are reported. [Co(dmgH) 2 (NO 2 ) 2 ] 2 [Ag] 2 · H 2 O shows two Ag I ions in different environments: one is in tetrahedral, whereas the other is in capped trigonal coordination and the metal‐organic framework in this molecule shows helical structure. A cyclic voltammetry study in [XCo(dioxime) 2 ] 2 ‐μ‐Pz and XCo(dioxime) 2 Pz [dioxime = dmgH (dimethylglyoximato), dpgH (diphenylglyoximato)] is reported. The reduction, Co III to Co II and Co II to Co I , is found to be more difficult in [XCo(dpgH) 2 ] 2 ‐μ‐Pz than in XCo(dpgH) 2 Pz. The CV data have been interpreted in terms of cobalt anisotropy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)