High-spin binuclear Co(II) complexes with a pendant octaazamaclocycle and carboxylates

Abstract

Three new binuclear Co(II) mixed-ligand complexes with N,N′,N′′,N′′′-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and mono-or dicarboxylate ligands were prepared and some of their physical properties were determined. The general formulas: [Co 2 (HCOO) 2 tpmc](ClO 4 ) 2 ·4H 2 O, [Co 2 (CH 3 COO) 2 tpmc](ClO 4 ) 2 and [Co 2 (tpht)tpmc](ClO 4 ) 2 ·4H 2 O (tphtH 2 = terephthalic acid) were proposed on the basis of elemental analyses (C,H,N) and molar conductivity. UV/Vis absorption and IR spectra, magnetic and CV measurements were used to study their geometries and properties. For the monocarboxylate complexes, an exo coordination of Co(II) with four nitrogens from tpmc and bis-bidentate bonded HCOO -/CH 3 COO -in the trans position is assumed. Tpmc adopts the chair conformation. For the dicarboxylate complex, it is supposed that a terephthalate dianion, as well as methylene chains from cyclam bridge two Co(II) atoms, while tpmc is in the boat conformation. The complexes were stable against chemical and electrochemical oxidation of Co(II) to Co(III). The data are compared with those for the previously published Cu(II) complexes containing the corresponding ligands and mutual similarities or differences were considered. Finally, some antibacterial activity of the complexes was found.

Thermal behavior and biological activity of [Co2(Cl)2 tpmc](BF4)2 complex

“…The mixed-ligand Co(II) complexes with tpmc and another additional ligand were intensively studied [2][3][4][5][6][7] but up to now the X-ray analysis has been performed for only three of them Co 2 (ox)tpmc(ClO 4 ) A great number of termodinamically stable Co(II) complexes with tpmc and other ligands (mono-or dicarboxylates, pseudohalides (NCO, NCS, NCSe) etc.) in macrocyclic enviroment are isolated [5][6][7]9]. Also, the biological activity of these complexes was examined.…”