Synthesis, properties, and electrochemical studies of a series of nickel(II) complexes with related macrocyclic ligands of varied unsaturation

Abstract

Aüfc.and ß for the various donors (1.4 kcal mol-1) could be ascertained.An immediate application of the procedure outlined above is to predict the enthalpy of adduct formation of bis(hexafluoroacetylacetonato)copper(II) with trimethylamine A-oxide in carbon tetrachloride. According to Table II, the reported value in o-dichlorobenzene should be corrected by A7i[Cu(hfac)producing a value of -12.8 kcal mol-1. It is of interest to consider what approach could be taken for a system in which no adduct could be found that is soluble in CC14 or C6Hi2. Thus, although a solvation-free displacement reaction could be obtained, one could not find a solvation-minimized adduct formation reaction for any dorior which could be subtracted to give the result for B'. A reliable spectroscopic method could be developed for estimating enthalpies from frequency shifts of donors (for example,

Synthesis, Structure, and Physicochemical Properties of Dinuclear NiII Complexes as Highly Efficient Functional Models of Phosphohydrolases

“…In addition to these transitions, another band is observed at 303 nm, which can be attributed to a charge-transfer transition involving orbitals from Ni II and the pyridine ligand, as previously observed for complex 1 14 and other Ni II complexes. [38][39][40] The redox properties of complexes 1 and 2 were investigated by cyclic voltammetry which revealed the presence of two irreversible anodic waves ( Figure S2) in CH 2 Cl 2 at 100 mV/s, with Fc + /Fc as the internal standard. The peaks at E ox1 ) 1.04, E ox2 ) 1.20 for complex 1 and E ox1 ) 0.73, E ox2 ) 0.94 V for complex 2 (vs NHE) are assigned to the irreversible stepwise one-electron oxidation couples Ni II Ni II / Ni II Ni III and Ni II Ni III /Ni III Ni III , respectively.…”

Investigation on the Interactions of NiCR and NiCR‐2H with DNA

“…Both complexes mainly oxidize guanines present in the bulge of 1 in the presence of KHSO 5 , and NiCR-2H more readily oxidizes guanines than NiCR. The oxidation potentials of NiCR and NiCR-2H should not be responsible for their difference in guanine oxidation because both complexes have similar oxidation potential values (1.03 V versus Ag/Ag + for NiCR and 1.05 V versus Ag/Ag + for NiCR-2H, in CH 3 CN) as previously determined in [20]. In fact, the better guanine oxidation by NiCR-2H might be attributable to its stronger coordination with guanines as described in 1 H NMR.…”

Bis(formamidine–urea) Complexes of NiII and CuII:Synthesis, Characterization, and Reactivity

“…Furthermore, epoxidation does not occur in the presence of the one-electron acceptor 2,6-di-tert-butyl-4-methylphenol. Aside from requiring somewhat higher concentrations, the catalytic properties of 5 are similar to those of nickel(II) compounds supported by tetradentate sulfonamide, [26] and di-N,NЈ-substituted oxamide ligands, [27] and differ from the cyclam-and salen-based systems, which are not catalytically active under Mukaiyama's conditions. Compound 5, in the presence of aldehyde and dioxygen, probably generates an acylperoxy radical, as proposed by Valentine and co-workers, [30] which has been shown to be a competent oxidant for olefin epoxidation.…”

“…[16,25,26] The deprotonated urea ligand of 5, therefore, does not favor the formation of a high valent Ni III species. The CV of complex 6 shows an irreversible reduction wave (data not shown).…”