Thiodiacetate and Oxydiacetate Cobalt Complexes: Synthesis, Structure and Stereochemical Features

Abstract

A series of cobalt complexes containing the dianionic ligands X(CH 2 COO) 2 2-(X = S, tda; or X = O, oda) is reported. O] n with 4,4Ј-di-tert-butyl-2,2Ј-bipyridine (tBu 2 -bipy), 2,3-bis(2-pyridyl)pyrazine (dpp) and 4,4Ј-bipyridine

Investigations of ternary complexes of Co(II) and Ni(II) with thiodiacetate anion and 1,10-phenanthroline or 2,2’-bipyridine in aqueous solutions

“…4). Such behaviour correlates very well with the ligand field stabilization energy (the LFSE) that favours to a greater extent the exchange of the coordination water for the high spin d 8 configuration of the nickel(II) ion than for the cobalt(II) ion (d 7 ) in an octahedral coordination environment [18].…”

Bonding interactions in oxydiacetate and thiodiacetate cobalt(II) and nickel(II) complexes

“…This finding explains the computed energy difference (ΔE) between fac and mer isomers in nickel(II) thiodiacetate complexes as well as the stability of the fac conformer of Co(tda)(H 2 O) 3 only. The geometric parameters of cobalt(II) thiodiacetate complexes could not be compared with the 3 ] were determined only by the IR inspection [14].…”

“…A survey of the literature reveals that in the solid state oda 2− when acts as a tridentate ligand adopts the facconformation in the [Ni(oda)(H 2 O) 3 ]1.5H 2 O monomer [13]. Cobalt(II) oxydiacetate complexes are mainly polymeric in nature [14]. The arrangement of oda 2− in the cobalt(II) complexes may be planar (mer-disposition) or non-planar (facdisposition).…”

“…It has been found that an increase of the number of the aqua ligands in the coordination sphere of Co 2+ hinders the oxygen donor atoms of the carboxylate groups to form additional coordination of another metal [6]. The tda 2− ligand exists invariably in the faccoordinating conformation forming the monomeric [Ni(tda)(H 2 O) 3 ] complex [17], as well as polymeric [Co(tda)(H 2 O)] n and monomeric [Co(tda)(H 2 O) 3 ] complexes [14]. In aqueous solutions, oxydiacetate and thiodiacetate complexes of Co 2+ and Ni 2+ exist as monomer species [14].…”

“…The tda 2− ligand exists invariably in the faccoordinating conformation forming the monomeric [Ni(tda)(H 2 O) 3 ] complex [17], as well as polymeric [Co(tda)(H 2 O)] n and monomeric [Co(tda)(H 2 O) 3 ] complexes [14]. In aqueous solutions, oxydiacetate and thiodiacetate complexes of Co 2+ and Ni 2+ exist as monomer species [14]. This is confirmed by the fact that two coordination water molecules can easily be displaced from these species upon the reaction with bidentate N-donor ligands [18,19].…”