Electrochemistry of the copper–nickel series of heteropolymetallic complexes [(μ4-O){NC5H4[C(O)NEt2 ]-3}4Cu4−x {Ni(H2O)}xCl6 ] (x = 0–4)

Abstract

The electrochemistry of the tetranuclear copper-nickel heteropolymetallic complexes [(µ 4 -O)L 4 Cu 4Ϫx {Ni-(H 2 O)} x Cl 6 ] [x = 0-4, L = N,N-diethylnicotinamide (denc)] were studied at a platinum electrode in dimethyl sulfoxide with 0.20 M tetrabutylammonium hexafluorophosphate as supporting electrolyte. At potentials more cathodic than Ϫ1.0 V the complexes are electrodeposited as Cu-Ni alloy and metal oxide films and display a complicated set of cyclic voltammographs. The voltammographs of all the Cu-containing complexes show a quasi-reversible redox couple in the potential range 0.250 to Ϫ0.450 V vs. Ag-AgPF 6 (0.01 M)-CH 3 CN. As the number of Cu atoms decreases in the complex, the peak currents i pa and i pc decrease proportionally and the peak potential shifts anodically. The cyclovoltammetric (CV) results indicate that electron transfer initially occurs only to the Cu II centres and that the electron-transfer reaction appears to be quasi-reversible. Using steady-state voltammetry at an ultramicroelectrode in combination with chronoamperometry at a microelectrode and exhaustive electrolysis at a Hg-pool electrode, the number of electrons (n) transferred for this initial reduction of the Cu 4 , Cu 3 Ni, Cu 2 Ni 2 and CuNi 3 complexes were 3.1, 2.1, 1.8 and 0.57, respectively. The diffusion coefficient for all the complexes was 2.2(±0.1) × 10 Ϫ6 cm 2 s Ϫ1 . The electronic spectrum of the Cu 4 complex taken after exhaustive electrolysis shows that one quarter of the Cu atoms remain in the Cu II form and that the Cu I complex remains stable. Since only a single CV peak results for all of the complexes, the electron transfer is most likely consecutive with very closely spaced EЊ potentials. A model based on statistically determined electron transfer to Cu II in particular faces is also proposed.

Excellent corrosion resistance of graphene coating on copper due to the low defect overlapping structure

“…Furthermore, the two peaks for O 1s 1/2 at the binding energy of 530.3 eV and 530.7 eV represented the Cu 2 O and CuO respectively. Moreover, the peaks transferred for O 1s 1/2 to 530.5 eV and 531.1 ev at the deep interface which was tallied with Cu 2 O [33,52]. The copper substrate was performed as the anode in galvanic corrosion and the corrosion reaction was shown in following equation [53], according to the SVET results, the anode reaction was accelerated by the high current density.…”

“…Figures 7(a) and (b) were obtained as the sample etched by laser at 1 KV for the 60 s, figures 7(c) and (d) were obtained by etching for 300 s, respectively. For figure 7(a), two peaks at the binding energy of 932.5 eV and 934.0 eV were attributed to the Cu, Cu 2 O, and CuO [51,52], respectively. However, for etching 300 s, the peaks of Cu 2p 3/2 transferred to 932.7 eV corresponding to the Cu and Cu 2 O, and the peak at 934.4 eV was in accord with CuO, shown in figure 7(c).…”

Preparation of thin film alloys with electrodeposition from heterotrinuclear M1–M2–M1 complexes (M1: NiII, CuII; M2: CuII, CoII, ZnII, CdII)

“…There are only two articles related to the deposition of metal alloys with the use of metal complexes containing heteronuclear metals. 17,18 In these studies Cu-Ni trans-metallation complexes were prepared by the use N,N¢-diethyl nicotine amide ligand to deposit Ni-Cu alloys with different stoichiometry on metal surfaces. The alloys thus prepared were characterized with X-ray diffraction (XRD), Auger and X-ray photoelectron spectroscopy (XPS) techniques.…”

Synthesis and Properties of a Molecular Dumbbell with Bis-μ4-oxo Copper(II/I) Hepta Metal Centers

“…The N−CH−N - angle of the linkage is av 125.8(2)°, indicating sp 2 hybridization of the central carbon atom. Each deprotonated molecular bowl L 3- accommodates three Cu II ions which are bonded to the μ 4 -oxo ion. − The three Cu II ions locate at the corners of a triangle of side av 3.290(1) Å. The μ 4 -oxygen is on a C 3 axis of the whole molecule and it is 0.467(3) Å (av) above the plane made by three Cu II ions.…”

“…Each deprotonated molecular bowl L 3accommodates three Cu II ions which are bonded to the µ 4 -oxo ion. [20][21][22] The three Cu II Variable-temperature (2-300 K) magnetic susceptibility of 3 was measured, and the plot of χ M T vs T is shown in Figure 2. 23 The value of χ M T decreases with decreasing temperature, indicating an antiferromagnetic coupling between the Cu II ions.…”