Cobalt(II) Complexes with Nitrogen Donors and Their Dioxygen Affinity in Dimethyl Sulfoxide

Abstract

The formation of Co II complexes with differently methylated N-donor ligands ethylenediamine (en), N,NЈ-dimethylethylenediamine (dmen), N,N,NЈ-trimethylethylenediamine (trmen), and N,N,NЈ,NЈ-tetramethylethylenediamine (tmen), has been studied at 298 K in both the aprotic solvent dimethyl sulfoxide (dmso) and in an ionic medium set to 0.1 mol dm −3 with Et 4 NClO 4 under anaerobic conditions. UV/Vis spectrophotometric and calorimetric measurements were carried out to obtain the thermodynamic parameters for the systems investigated. Only mononuclear CoL j 2+ complexes were formed (j = 1−3 for en, j = 1, 2 for dmen; and j = 1 for trmen and tmen) where the diamines act as bidentate agents.

Thermal Reduction of CoIII(pn)2Cl(L)2+-Fe(II) Ions in Aqueous-Organic Solvent Medium via Outer-Sphere Electron Transfer Approach

“…where L = RC 6 H 5 NH 2 , R = m-OCH 3 , p-F and H) complexes are presented in Table-1 and are based on our experimental observations. Cyclic voltammetry: The voltammograms of Co(III) complexes show the two peaks which correspond to two single electron transfer processes [16]. There is both oxidation and reduction waves appearing in this potential range, suggesting that the complexes are inert.…”

Solvent control on the electron transfer reaction between CoIII(en)2Br(L)2+–Fe(CN) (L = aryl amines) by regression relationships: the PXRD and electrochemical investigations

“…Figure 2 illustrates the cyclic voltammogram of Co III (en) 2 Br( m ‐OMeC 6 H 4 NH 2 ) 2+ in DMF showing two peaks which correspond to two single ET processes 30. Table 1 is the electrochemical data obtained for the cobalt(III) complexes for the reduction processes: Co III /Co II and Co II /Co I in DMF at GCE 31, 32.…”

Crystal structure of hexakis(dimethyl sulfoxide-κO)cobalt(II) bis[trichlorido(quinoline-κN)cobaltate(II)]

“…The packing of (Comuzzi et al, 2002), while a subsequent report lists Co-O distances in the range 2.088 (2)-2.110 (2) Å , with O-Co-O (cis) angles between 85.26 (7) and 93.67 (8) (Chan et al, 2004). In [Co(Me 2-SO) 6 ][SnCl 6 ], both the cobalt and tin metal ions display an octahedral environments, with the Co-O bond lengths reported between 2.093 (4) and 2.113 (5) Å (White et al, 2007).…”

“…Although Me 2 SO is typically coordinated to a metal via the oxygen atom (Sipos et al, 2015;Calligaris, 2004;Calligaris & Carugo, 1996), there are examples in which Me 2 SO serves as an S-donor, as illustrated by the ruthenium complex [mer-RuCl 3 (acv)(Me 2 SO-S)(C 2 H 5 OH)]ÁC 2 H 5 OH (acv = acyclovir) (Turel et al, 2004). With regard to cobalt, it has been noted that Co II is a hard acceptor preferring hard-donor atoms like oxygen in Me 2 SO, the bonds being mainly electrostatic in nature (Comuzzi et al, 2002). Nevertheless, while Me 2 SO coordination to cobalt through the soft-donor sulfur atom (rather than the oxygen atom) is rare, there are some notable examples.…”