Triazene 1-oxide Research Articles

Synthesis of high-spin five-co-ordinate Lewis-base adducts of bis(triazen-1-olato)cobalt(II). Studies of reversible dioxygen binding

High-spin five-co-ordinate Lewis-base adducts of cobalt(II) triazene 1-oxide complexes have been prepared and their reactivity in reversible dioxygen binding studied. Monoclinic spin-Hamiltonian parameters are reported for the dioxygen complexes. An X-ray structure analysis of high-spin bis[3-(4-chlorophenyl)-1-methyltriazen-1-olato]cobalt(II)–pyridine (1/1) has been performed. The adduct crystallizes in the monoclinic system, space group P2/c, with a= 18.39(2), b= 12.553(9), c= 9.827(8)A, β= 105.65(7)° and Z= 4. The co-ordination about the cobalt atom is distorted trigonal bipyramidal.

ChemInform Abstract: CHEMISTRY OF RUTHENIUM. PART 10. TRIAZENE 1‐OXIDE COMPLEXES OF BIS(2,2′‐BIPYRIDINE)RUTHENIUM(II) AND ‐(III). SYNTHESIS, SPECTRA, AND ELECTROCHEMISTRY

AbstractDie wie aufgezeichnet synthetisierten Ru(II)‐Titelkomplexe (III) werden durch Elementaranalysen, molare Leitfähigkeiten, elektronen‐ und IR‐spektroskopische Daten charakterisiert.

ChemInform Abstract: CHEMISTRY OF RUTHENIUM. PART 8. NEW TRIS COMPLEXES OF RUTHENIUM(III). SYNTHESIS, SPECTRA, AND REDOX ACTIVITY

AbstractDie Reaktion einer siedenden EtOH‐Lösung von RuCl3 mit Triazen‐1‐oxiden liefert die Titelkomplexe (I) mit seltener mer‐Struktur, die durch IR‐ und Elektronenspektren charakterisiert wurden.

Chemistry of ruthenium. Part 8. New tris complexes of ruthenium(III). Synthesis, spectra, and redox activity

A group of new low-spin tris complexes of ruthenium(III) has been synthesized using triazene 1-oxides, RN(O)N–NH–C6H4X-p(HL; R = Et or Ph, X = Me, H, Cl, CO2Et, or NO2) as ligands. The green to yellow-green complexes [RuL3] are believed to have a meridional RuN3O3 co-ordination sphere. They display ligand → metal charge-transfer transitions in the region 550–750 nm. In acetonitrile solution the [RuL3] complexes exhibit a quasi-reversible RuIII–RuII couple (E2980, –0.6 to –1.2 V vs. s.c.e.) and a nearly reversible RuIV–RuIII couple (E2980, 0.2–0.7 V vs. s.c.e.) at a platinum working electrode. The E2980 values of both couples correlate linearly with the Hammett constant of substituent X. The reaction constants lie in the range 0.1–0.2 V. The electronic spectra of [RuL3]– and [RuL3]+ are briefly reported. The former complex is unstable.

Chemistry of ruthenium. Part 10. Triazene 1-oxide complexes of bis(2,2′-bipyridine)ruthenium-(II) and -(III). Synthesis, spectra, and electrochemistry

Mixed ruthenium complexes of type [Ru(bipy)2L]ClO4·H2O derived from 2,2′-bipyridine (bipy) and triazene 1-oxides, RN(O)N–NH–C6H4X-p(HL: R = Et or Ph; X = Me, H, Cl, CO2Et, or NO2) are described. In solution they display two quasi-reversible reductions due to electron transfer to co-ordinated bipy units. The RuIII–RuII couple occurs in the range 0.16–0.44 V versus s.c.e. The formal potential of this couple is linearly related to the Hammett constant of substituent X. The low-spin ruthenium(III) analogue, [Ru(bipy)2L]2+, is furnished by both coulometric and chemical oxidations. The energy of the ligand-to-metal charge-transfer band of [Ru(bipy)2L]2+ correlates linearly with the RuIII–RuII formal potential.

ChemInform Abstract: ELECTRON TRANSFER IN GROUPS OF IRON, COBALT, AND COPPER TRIAZENE 1‐OXIDES: HAMMETT CORRELATION, LIGAND REDISTRIBUTION, AND CRYSTAL FIELD EFFECTS

Chemischer InformationsdienstVolume 13, Issue 19 Article ChemInform Abstract: ELECTRON TRANSFER IN GROUPS OF IRON, COBALT, AND COPPER TRIAZENE 1-OXIDES: HAMMETT CORRELATION, LIGAND REDISTRIBUTION, AND CRYSTAL FIELD EFFECTS R. N. MUKHERJEE, R. N. MUKHERJEESearch for more papers by this authorO. A. RAJAN, O. A. RAJANSearch for more papers by this authorA. CHAKRAVORTY, A. CHAKRAVORTYSearch for more papers by this author R. N. MUKHERJEE, R. N. MUKHERJEESearch for more papers by this authorO. A. RAJAN, O. A. RAJANSearch for more papers by this authorA. CHAKRAVORTY, A. CHAKRAVORTYSearch for more papers by this author First published: May 11, 1982 https://doi.org/10.1002/chin.198219094AboutPDF 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 onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume13, Issue19May 11, 1982 RelatedInformation

Electron transfer in groups of iron, cobalt, and copper triazene 1-oxides: Hammett correlation, ligand redistribution, and crystal field effects

The electron-transfer behavior of groups of pseudooctahedral ML3 and grossly planar Ca, complexes is reported (M Fe. Co; L triazene 1-oxide). A quasi-reversible proccess of type MLp+ e-⇌ML3(p=2,3) is identified with electrochemical techniques. The E°298 values (vs. SCE) fall in the following ranges: Fe, -O.76 to -0.14; Co, -0.56 to -0.08; Cu, -1.07 to -0.37. The values become more negative in the order CoL3, FeL3, and CuL2. For a given metal ion, E°298 shifts appreciably with ligand substituent. and a linear Hammett relationship is obeyed. The reaction constant is shown to decrease considerably when an extra bond intervenes between the metal and the substituent. Copper(II) complexes of bidentate ligands carrying an ortho substituent as well as the of a tetradentate ligand that enforce cis planar stereochemistry display abnormally negative shifts of E°298. When two iron(III) complexes are mixed, ligand scrambling occurs and the presence of mixed species is neatly established by cyclic voltammetry. The mixed complexes fit smoothly into the Hammett straight lines. The thermodynamic quantities controlling the trends of E°298 are considered. An attempt is made to assess the relative importance of spherical and nonspherical parts of the crystal fields. Among complexes of the same metal ion, it is possible to express the shift of E°298 in terms of the crystal field splitting parameter with a large proportionality constant. The copper(II) complexes show a ligand field band whose energy linearly correlates with E°298. The shift of E°298 between iron and cobalt couples is controlled by metal ionization potential and nearly equally important spherical and nonspherical crystal field contributions.

Spectral and Mössbauer studies of some iron(III) high spin complexes

Some new iron(III) complexes of triazene 1-oxides are synthesised and characterised by analysis, magnetic, electronic and Mossbauer spectra. They are found to be high spin Fe3+ systems.

Spectral and magnetic behaviour of some nickel(II) and cobalt(II) complexes of triazene 1-oxides

Some new nickel(II) and cobalt(II) complexes of triazene 1-oxides derived from amino pyridines are reported. Experimental evidence shows that the nickel(II) complexes are planar in the solid state but exhibit a planar⇋pseudooctahedral equilibrium. The pseudooctahedral species for the (RPyCl) 2Ni complexes involves chloro coordination. In chloroform solution the equilibrium shifts substantially to the right compared to benzene solution for these complexes. In the corresponding cobalt(II) complexes, the chloro-coordination is complete and the complexes have a distorted octahedral symmetry in both solid and solution phases.

New planar cobalt(II) and nickel(II) complexes

Some planar complexes of cobalt(II) and nickel(II) derived from triazene 1-oxides are reported in this paper. The cobalt(II) complexes are very stable and are shown to be monomolecular in solution. Their magnetic moments lie in the range 2.08–2.19 BM. They show electronic spectra with many features in the range 4500–30,000 cm −1. Probable assignment schemes are suggested on the basis of a strong field model. In one of these schemes the spectra of the cobalt(II) and nickel(II) complexes can be understood on the basis of a single set of crystal field and Slater-Condon parameters. In pyridine solution the cobalt(II) and nickel(II) species exist in equilibrium with high spin adducts. The thermodynamic parameters ΔH′ and ΔS′ for the equilibrium are determined for nickel(II) species from variable temperature magnetic data. It is shown that adduct formation is more exetensive in the case of cobalt(II) than in the case of nickel(II).

Hydrogen bonding in triazene 1-oxides

Infrared data is used to show that triazene 1-oxides exist both as intermolecular and as intramolecular hydrogen bonded species in solution except in the case of ortho substituted compounds which exhibit only intramolecular hydrogen bonding.

Spectral and magnetic behavior of some cobalt(II) and nickel(II) complexes involving coordination by the halo group

Halo groups attached to benzene rings are capable of occupying coordination positions in some triazene 1-oxide complexes of the general stricture 1. On the basis of comparisons of magnetic moments and electronic spectra of the various complexes with those of one cobalt(II) complex of definitely known structure it is concluded that all the cobalt(II) complexes except one (X = I) are pseudooctahedral both in the solid state and in the solution phase (benzene) in which the complexes are mono-meric. The iodo complex is grossly planar in the crystalline state but becomes pseudooctahedral in the solution phase. All the pseudooctahedral complexes show splitting of the si crystal field band The splittings (which follow the orders F 3 2 ) are attributed to the low symmetry of the ligand field. In this class of complexes, the octahedral quartet state of cobalt(II) is more readily achieved than the octahedral triplet state d nickel(II). Among nickel-(II) complexes. those having X=OCH 2 , OC 2 H 2 , and SCH 2 show magnetic moments and electronic spectra typical of a dis-toned octahedral geometry both in solid and in solution. On the other hand, nickel(II) complexes with X= halogen are diamagnetic in the crystalline state but become partially paramagnetic In the solution phase. On the basis of spectral and magnetic data it is shown that planar (S=O) preudoonahedral (S=1) equilibria exist in these solutions. The. pseudo- octahedral form invoices halogen coordination. The population of the octahedra/ configuration follows the order F I. The parameters ΔH°(and ΔS°)for the equilibria are found to be positive. A possible rationalization is discussed on the basis of a simple model.

Some observations on triazene 1-oxide complexes of bivalent nickel, palladium and copper

Several triazene 1-oxide chelates of nickel(II), palladium(II) and copper(II) are described. These complexes show crystal field bands at unusually low energies. The nickel(II) complexes are uniformly diamagnetic in the solid state. However, in the solution (benzene, chloroform) phase a slight paramagnetism develops in all nickel(II) complexes except those having a non-coordinating substituent in the ortho position of the benzene ring. The pmr spectra of the partially paramagnetic complexes show small contact shifts. These shifts can be qualitatively interpreted on the basis of the existence of unpaired spin density in a π-orbital. The palladium(II) complexes having a substituent in the ortho position of the benzene ring exist in isomeric forms. In one case the isomeric forms have abeen separated by chromatography on a column of alumina. The copper(II) complexes have normal magnetic moments.