Chemistry Of Nickel Research Articles

Chemistry of tetravalent nickel and related species. 2. Cyclic voltammetry of oxidation-reduction equilibriums involving protons

The redox behavior of nickel(II) and nickel(IV) species derived from a few hexadentate ligands of type 1 (H 2 RR'L) have been thoroughly studied in buffered media over a wide range of pH using cyclic voltammetry and coulometry. The results for the system having R=R'= Me are representative. At pH 2 L) 2+ =Ni(H 2 Me 2 L) 2+ (E° 298 =0.71 V vS. SCE) is observed. At pH >6. two distinct reversible one-electron processes arc observed. One of these has no proton involvement: Ni(Me 2 L) 2+ -Ni(Me 2 L) + has E° 298 =0.42 V vs. SCE The second couple may or may not involve protons: pH∼7, Ni(Me 2 L) + -Ni(HMe 2 L)+, E° 298 = 0.64 V vs. SCE; pH >8.45, Ni(Me 2 L) + -Ni(Me 2 L), E° 298 =0.15 V vs. SCE. The nickel(II) species involved in each couple is what is expected from acid dissociation data: pK 2 = 5.90, pK 2 = 7.80. The observed transition of the single twaclecanyi couple into two one-electron couples as the pH is raised can be rationalized on the basis of the higher proton affinity of the nickel(II) species. It is estimated that the couple Ni(Me 2 L) + -Ni(H 2 Me 2 L) 2+ has E° 298 =1.01 V. The nickel(III) intermediate Ni(Me 2 L) + is relatively unstable. However a paramagnetic solid containing nickel(III) has been obtained by oxidation of Ni(H 2 Me 2 L) 2+ . In the polycrystalline phase it shows room-temperature EPR signals characteristic of axial symmetry (g=2.04:g⊥= 216). The one-electron redox behavior of Fe(H 2 Me 2 L) 2- is briefly reported and an empirical relationship between E° 298 values of nickel(III)-nickel(II) and iron(III)-iron(II) couples is noted.

A Review of: “The Organic Chemistry of Nickel. Volume II. Organic Synthesis, by P. W. Jolly and G. Wilke, Academic Press, 1975, 400 pp. plus xv. $48.00”

A Review of: “The Organic Chemistry of Nickel. Volume II. Organic Synthesis, by P. W. Jolly and G. Wilke, Academic Press, 1975, 400 pp. plus xv. $48.00”

Chemistry of tetravalent nickel and related species. I. 6-Manganese coordination octahedra generated from hexadentate oxime ligands

Hexadentate ligands (H 2 RR'L) of type 1 readily yield high-spin nickel(II) complexes. Ni(H2RR'L)X 2 (X = CIO 4 , NO 3 ), in which the coordination polyhedron is octahedral NiN 6 and Dq is∼1300m -1 . These arc readily oxidized to red diamagnetic Ni(RR'L)X 2 by chemical and electrochemical means. The oxidized complexes aintain tctravakru nickel held in an octahedral NiN 6 core. They show two intense ligand → metal charge transfer transitions in the visible region. The charge transfer state also makes some contribution to the ground state fir data). Ni(RR'L) 2+ oxidizes quantitatively 2 mol of Fe 2+ to Fe 3+ . The potential of the half•cell reaction Ni(RR'L) 2+ H + +2e=Ni(H 2 RR'L) 2+ is determined using a direct potentiometric method. E° 298 (vs. normal hydrogen electrode) is found to lie in the range 0.90-0.94 V for the systems studied. The possible role of the negative charge on the =N-0 - moiety in minimizing the effective pasiEvc charge on the metal in Ni(RR'L) 2+ is discussed. The spectroscopic properties of the low-spin complexes of H 2 Me 2 L with two other d6 ions, viz., iron(II) and cobalt(III) are compared with those of the nickel(IV) species.

ChemInform Abstract: HIGHER OXIDATION STATE CHEMISTRY OF IRON, COBALT AND NICKEL

Chemischer InformationsdienstVolume 5, Issue 51 Preparative Inorganic Chemistry ChemInform Abstract: HIGHER OXIDATION STATE CHEMISTRY OF IRON, COBALT AND NICKEL W. LEVASON, W. LEVASONSearch for more papers by this authorC. A. MCAULIFFE, C. A. MCAULIFFESearch for more papers by this author W. LEVASON, W. LEVASONSearch for more papers by this authorC. A. MCAULIFFE, C. A. MCAULIFFESearch for more papers by this author First published: December 24, 1974 https://doi.org/10.1002/chin.197451071AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume5, Issue51December 24, 1974 RelatedInformation

The coordination chemistry of divalent cobalt, nickel and copper. Part V: Five-coordinate complexes of copper dichloride with new pyridine dicarboxamide ligand

The coordination chemistry of divalent cobalt, nickel and copper. Part V: Five-coordinate complexes of copper dichloride with new pyridine dicarboxamide ligand

Higher oxidation state chemistry of iron, cobalt, and nickel.

Higher oxidation state chemistry of iron, cobalt, and nickel.

The co-ordination chemistry of divalent cobalt, nickel and copper. Part I. Five-coordinate copper(II) complexes with new thiodiacetamide ligands

Preparation and properties of new penta-coordinate copper(II) complexes using ligands with OSO sets of donor atoms, viz. N,N,N′,N′-tetramethylthiodiacetamide (TTDA) and N,N′-dimethyl-N,N′-diphenylthiodiacetamide (DTDA), are reported. Spectral and conductivity data show that CuX 2L (X=Cl −, Br −, NO 3 −; L=TTDA and DTDA) are penta-coordinate in both the solid state and solution. These are compared with copper(II) complexes prepared by using other similar tridentate ligands. Spectral data and X-ray structural analysis (reported earlier) indicated a slightly distorted square pyramidal structure for CuCl 2. TTDA.

IX. Researches in chemical equivalence. Part III. Nickelous and Cobaltous Sulphates

Although the chemistry of nickel and cobalt is interesting from many points of view, it is more especially attractive from the probable isomerism of these metals. Their combining proportions, in fact, according to the most valuable evidence we possess, appear to be entirely the same. We, therefore, thought it very advisable to inquire on what terms they might prove to be mutually equivalent: and the particular equivalence we have examined has been equivalent precipitability of the sulphates, by sodic hydrate, from an aqueous solution.