Cobalt Chemistry Research Articles

Complexes of functional phosphines. 23. PPh3 and .beta.-ketophosphine complexes of cobalt(II). Crystal and molecular structures of CoCl2[Ph2PCH2C(O)Ph]2 and Co2(CO)6[Ph2PCH2C(O)Ph]2 and of the trinuclear, mixed-metal complex [(Ph3P)2Ag(.mu.-Cl)2Co(.mu.-Cl)2Ag(PPh3)2].cntdot.0.50Et2

The solution chemistry of cobalt(II) ketophosphine complexes CoX 2 [Ph 2 PCH 2 C(O)Ph] 2 (1a, X=Cl; 1b, X=Br, 1c, X=I) has been examined and compared to that of [CoX 2 (PPh 3 ) 2 ] (2a, X=Cl; 2b, X=Br; 2c, X=I). All the complexes undergo a tetrahedral-octahedral equilibrium in methanol. This is facilitated by solvent coordination rather than by the ligands keto functions. Some degree of ligand displaccment also occurs. A crystal structure of 1a has been elucidated, showing a pseudotetrahedral cobalt(II) geometry

Recent Investigations on the Heterometallic Alkoxide Chemistry of Cobalt, Nickel and Copper

Recent Investigations on the Heterometallic Alkoxide Chemistry of Cobalt, Nickel and Copper

Comparative study on the coordination chemistry of cobalt(II), nickel(II), and copper(II) with derivatives of salen and tetrahydrosalen: metal-catalyzed oxidative dehydrogenation of the carbon-nitrogen bond in coordinated tetrahydrosalen

The salen complexes ML (M II =Cu, Ni, Co) and the corresponding tetrahydrosalen complexes M[H 4 ]L (M II =Cu, Ni) were prepared and characterized by their vis absorption and EPR spectra, by their magnetic moments, and by cyclic voltammetry in acetonitrile

Ultraviolet–visible–near-infrared and EXAFS study of CoIIcoordination chemistry in post-doped silica sol–gel glasses

UV–VIS–NIR and EXAFS spectroscopies have been used to probe the coordination chemistry of cobalt(II) in post-doped silica sol–gel glasses. Materials doped with cobalt(II) chloride, nitrate and acetate were prepared and the cobalt(II) coordination chemistry was studied in relation to post-doping treatments such as dehydration, rehydration and densification. Both octahedral and tetrahedral coordination geometries were observed for the hydrated and dehydrated gel glasses with pronounced anion coordination present in all dehydrated samples. The presence of salts in the gel-glass pore structure provided additional absorbing centres for water. The extent of associated water adsorption (hydrogen bonded to silanol groups and hydrogen bonded to other water molecules) in the pores varied in the order nitrate > chloride > acetate. When the sample was sintered cobalt was incorporated in the glass framework and anions and water were lost.

Structure and chemistry of cobalt in CoAPO-5 molecular sieve

The single crystals of various cobalt contained tetraethylamine (TEA) CoAPO-5 molecular sieves were studied by X-ray diffraction. The structure was refined to give a final R value of 0.065–0.067. The Al—O and P—O bond lengths and Al—O—P angle of the AlPO4-5 framework were distorted by incorporation of cobalt. The coordination environment of cobalt in CoAPO-5 was studied by EPR and IR spectroscopies. One oxygen signal was observed on the oxidized CoAPO-5 samples with g= 2.00. After NO was adsorbed on the sample, EPR spectra of oxidized and reduced CoAPO-5 showed eight hyperfine splittings due to the interaction between Co(I= 7/2) and N. The adsorption of NO probe molecules on reduced CoAPO-5 gave two strong bands at 1894 and 1814 cm–1 while the oxidized CoAPO-5 gave a weak band at 1860 or 1845 cm–1. The cobalt in oxidized CoAPO-5 was reduced by NO treatment and remained in the tetrahedral framework. There is an additional weaker acid site on oxidized CoAPO-5 in comparison with reduced CoAPO-5 detected by TPD of ammonia.

Thermochromic behavior of cobalt(II) halides in nonaqueous solvents and on filter paper

This paper presents two phenomenon of cobalt chemistry that are aesthetically pleasing, relatively safe, and suitable for class experimentation and demonstration.

ChemInform Abstract: Some Aspects of the Organic Chemistry of Cobalt

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The coordination chemistry of divalent cobalt, nickel and copper Part 14. The characterisation of copper complexes with potentially bidentate ligands having phosphorus oxide and tertiary amine donor groups: a crystal structure of chlorobis( P-( N, N-dimethylaminomethyl)- P, P-diphenylphosphine oxide)copper(II) Tetrachlorocuprate(II)

The three ligands P-dimethylaminomethyl- P-phenylphosphinic acid, dapa, P-( N, N-dimethylaminoethyl)- P, P-diphenylphosphine oxide, depo, and P- N, N-dimethylaminomethyl)- P, P-diphenylphosphine oxide, dmpo, were prepared. Copper complexes were isolated and characterised. The coordination sphere of Cu(dapa) 2·H 2O was assigned a distorted octahedral symmetry consisting of two amine nitrogen, one water oxygen and three phosphinic acid oxygen atoms, the phosphinic acid group of one dapa ligand being coordinated to two copper atoms. Compound CuCl 3(H·depo) was found to have a distorted tetrahedral chromophore containing the three chlorine and an amine nitrogen as donor atoms. A crystal structure determination was performed on (CuCl 2) 3(dmpo) 4; tetragonal, space group P 4 2 1 c, a = b = 15.330(2), c = 13.992(4) Å, Z = 2. The compound consisted of two penta-coordinate [Cu(dmpo) 2Cl] + cations and a tetragonally distorted CuCl 4 2− anion. The symmetry of the chromophores of the cations was highly distorted square pyramidal, the donor atoms being the phosphine oxide oxygen and amine nitrogen from each of two dmpo ligands and the chlorine atom. An analogous structure was assigned to (CuBr 2) 3(dmpo) 4.

The coordination chemistry of divalent cobalt, nickel and copper. Part 8. Selected complexes containing N-substituted pyridine-2,6-dicarboxamide ligands; crystal structure of dibromo( N,N′-dimethyl- N,N′-diphenylpyridine-2, 6-dicarboxamide)nickel(II)

Diverse complexes of divalent cobalt, nickel and copper and the ligands N,N,N′,N′-tetramethylpyridine-2,6-dicarboxamide (tdpa), N,N′-dimethyl- N,N′-diphenylpyridine-2,6-dicarboxamide (dpda) and N,N,N′,N′-tetraisopropylpyridine-2 ,6-dicarboxamide (ppda) were discussed in order to illustrate the properties of these ligands. The complexes [M-(ppda) 2](ClO 4) 2 (M = Co, Ni and Cu) and [Co-(ppda) 2] (ClO 4) 2(acet) (acet = acetone), had distorted octahedral chromophores. The distortion was most pronounced in [Cu(ppda) 2](ClO 4) 2. This severe distortion was not present in octahedral [Ni(tdpa) 2]-(CIO 4) 2. Isostructural, crystalline (MCl 2) 3(tdpa)1 2 (M= Ni and Co) were isolated from hot solutions. The solid reflectance spectra were resolved into gaussian components. This data, in conjunction with infrared and magnetic measurements, enabled the assignment of the formula [MCl(tpda)] 2[MCl 4] to these complexes. The anion was found to be tetrahedral while the cation had a distorted tetrahedral chromophore. The reaction of NiBr 2 with dpda produced two complexes; green αNiBr 2(dpda) was isolated at room temperature while red βNiBr 2(dpda) was obtained from hot solution. Characterisation data indicated αNiBr 2(dpda) to have a pentacoordinate chromophore. The characterisation data for βNiBr 2(dpda) was ambiguous and a crystal structure determination was performed (monoclinic crystal, space group P2 1/ a with a = 13.871, b = 16.019, c = 9.878Å, β = 95.492°, final R factor = 0.0549 and N obs = 2221). The Ni was in a distorted square pyramidal environment with the donor atoms of dpda and a bromine atom constituting the basal plane and the remaining bromine atom occupying the apical position. The coordination spheres of the crystalline complexes NiBr 2(dpda)(dmp) (dmp = 2,2-dimethoxypropane) and NiBr 2(dpda)(acet) were analogous to those of αNiBr 2(dpda) and βNiBr 2(dpda) respectively.

The co-ordination chemistry of divalent cobalt, nickel, and copper. Part 13. Characterization and stability constants of copper(II) species isolated from mixed-ligand solutions; crystal structure of the complex (pyridine-2,6-dicarboxylato)(N,N,N′,N′-tetramethyl-1,3-diaminopropane)copper(II)

Six-co-ordinate complexes [Cu(pydca)(L)(H2O)]·H2O and five-co-ordinate complexes [Cu(pydca)(L)], where pydca = pyridine-2,6-dicarboxylate, L = en (1,2-diaminoethane), tmen (N,N,N′,N′-tetramethyl-1,2-diaminoethane), pn (1,3-diaminopropane), or pen [1,2-di(pyrrolidin-1-yl)ethane], were isolated and characterized by thermogravimetric, calorimetric, spectrophotometric, magnetic, and stability constant measurements. A structure determination on [Cu(pydca)(tmpn)](tmpn =N,N,N′,N′-tetramethyl-1,3-diaminopropane), which was monoclinic, with space group P21/c, a= 14.970(2), b= 7.290(1), c= 14.822(2)Å, β= 106.64(2)°, Z= 4, indicated a distorted square-pyramidal co-ordination sphere with considerable steric interaction between the tertiary amine groups and the two carboxylate groups. The splitting of the νsym(COO) and νasym(COO) i.r. bands of all the above complexes having tertiary amine ligands was ascribed to the distortions resulting from this steric interaction. Stability constants for some complexes are reported.

Structural chemistry of cobalt(III) complexes of thioacylhydrazide and thioacylhydrazonate ligands. Crystal structures of (-)D-fac-tris(thioacethydrazide)cobalt(III) chloride, (-)D-fac-tris(formaldehyde thioacethydrazidato)cobalt(III) hydrate, and fac-tris(thiosemicarbazide)cobalt(III) chloride

Structural chemistry of cobalt(III) complexes of thioacylhydrazide and thioacylhydrazonate ligands. Crystal structures of (-)D-fac-tris(thioacethydrazide)cobalt(III) chloride, (-)D-fac-tris(formaldehyde thioacethydrazidato)cobalt(III) hydrate, and fac-tris(thiosemicarbazide)cobalt(III) chloride

(Sulfito)cobalt(III) chemistry: synthesis of cis-aquabis(ethylenediamine)(sulfito)cobalt(1+) and the kinetics of cis to trans isomerization

(Sulfito)cobalt(III) chemistry: synthesis of cis-aquabis(ethylenediamine)(sulfito)cobalt(1+) and the kinetics of cis to trans isomerization

ChemInform Abstract: The Coordination Chemistry of Divalent Cobalt, Nickel and Copper. Part 12. A Comparison of the Nature of the Cobalt and Nickel Complexes Isolated When Using P‐(N,N‐Dimethylaminomethyl)‐P,P‐diphenylphosphine Oxide and P‐(N,N‐Dimethylaminoethyl)‐P,P‐diphenylphosphine Oxide as Ligands.

AbstractThe title ligands (I) and (II) react with selected cobalt and nickel salts to yield the complexes (III)‐(IX).

The coordination chemistry of divalent cobalt, nickel and copper. Part 12. A comparison of the nature of the cobalt and nickle complexes isolated when using P-( N,N-dimethylaminomethyl)- P,P-diphenylphosphine oxide and P-( N,N-dimethylaminoethyl)- P,P-diphenylphosphine oxide as ligands

The ligands P-( N,N-dimethylaminomethyl)- P,P-diphenylphosphine oxide (dmpo) and P-( N,N-dimethylaminoethyl)- P,P-diphenylphosphine oxide (depo) were reacted with selected divalent cobalt and nickel salts. The resultant complexes were analysed and characterised. In all cases dmpo behaved as a bidentate ligand by coordinating through the amine and phosphine oxide groups while depo usually reacted in a monodentate manner. The complexes (MX 2) 3(dmpo) 4, where M = Co, Ni and X = Cl, Br, were shown to consist of two pentacoordinate M(dmpo) 2X + cations and one tetrahedral MX 4 2− anion. Reaction of equimolar quantities of CoCl 2 and depo resulted in the isolation of CoCl 3(H·depo). This complex was found to have a tetrahedral coordination sphere consisting of three chloride atoms and one phosphine oxide. It was suspected that a tautomerism type reaction produced the proton in H·depo +. The corresponding NiCl 3(H·depo)complex could only be obtained by the addition of hydrochloric acid. The reaction of equimolar amounts of CoCl 2, dmpo, and HCl yielded (H·dmpo) 2[CoCl 4]. The complex Co(dmpo) 2(SCN) 2 which contained two N-bonded thiocyanate groups was assigned a distorted octahedral coordination sphere. However, in Co(depo) 2(SCN) 2 the phosphine oxide groups did not bond and the coordination sphere had a distorted tetrahedral symmetry. The insoluble nature of Ni(depo) 2(ClO 4) 2·2H 2O resulted in inconclusive characterisation data. The complexes [M(dmpo) 2(mecn) 2](ClO 4) 2, mecn = methyl cyanide, were assigned an octahedral coordination sphere. Removal of methyl cyanide from this sphere resulted in complexes in which there was evidence for interaction between the perchlorate groups and the metal ions.

Crystal chemistry of cobalt and nickel in lithiophorite and asbolane from New Caledonia

The crystal chemistry of Ni- and Co-bearing manganese oxides (lithiophorite and asbolane) has been investigated by X-ray Absorption Spectroscopy (XAS). The Mn oxides come from the lateritic weathering profiles of the ultrabasites of New Caledonia. The distinct behaviours of Ni and Co concern both oxidation states and local structures. The electronic structure and short range order around Co atoms do not depend on the nature of the Cocontaining phase. Co atoms are trivalent and 6-fold coordinated. Co-(O, OH) and Co-(Co, Mn) interatomic distances derived from EXAFS are equal to those found around Mn atoms which rules out the possibility of an adsorption of Co atoms directly above and below vacancies of MnO 2 layers. The high structural order around Co contrasts with the structural disorder observed around Mn. Cobalt atoms do not occupy specific Mn sites and are not randomly distributed within the octahedral Mn layers. Unlike Co, Ni exhibits distinct surroundings in both phases. In asbolane, Ni atoms build partial Ni(OH) 2 layers. Ni-OH distances are lower as compared with the free Ni hydroxide because of the formation of hydrogen bonds between Ni(OH) 2 and MnO 2 layers. In lithiophorite Ni atoms are located in the hydrargillite layer (Al(OH) 3). Both chemical composition and structural considerations militate for a Ni for Li substitution in lithiophorite. Finally, evidence is given for the existence of a mixed-layering between lithiophorite and asbolane and the chemical variations generally observed in these Mn oxides are interpreted as a variable proportion of (Mn, Co)(O, OH 2, Ni(OH) 2 and (Al, Li, Ni)(OH) 3 layers.

Ligand and induced internal redox processes in Mo- and W-S systems

This paper reviews recent work from our laboratory on redox chemistry of Mo-S systems. Mo and S are each capable of existing in multiple oxidation states. When found together in the same compound, these elements elicit numerous redox possibilities. The classical situation involving simple changes in the oxidation state of Mo is well known. Recent work has also documented the ability of coordinated S ligands (e.g. S 2−, S 2− 2 and S 2− 4) to undergo redox while Mo remains in a given state of oxidation. In this paper cases are presented wherein both the Mo and S oxidation states change. For example, the reaction of the red MoS 2− 4 ion with organic disulfides gives the purple Mo 2S 2− 8 ion in high yield. The oxidizing disulfide added to the hexavalent MoS 2− 4 ion leads quantitatively to the reduced pentavalent dinuclear Mo 2S 2− 8 ion. Mechanistically, this reaction proceeds in two stages involving a green intermediate of yet unknown structure. The net reaction embodies an induced internal electron transfer from S to Mo in the same sense that Taube et al. elucidated in the chemistry of cobalt. Application of the concept of induced internal electron transfer allows access to new low-valent Mo-S systems by adding oxidants to Mo(VI)-S species. For example, the reactions of MoS 2− 4 with thiuram disulfides give compounds of the form MoS 2(S 2CNR 2) 3 (R = Et or iBu). These are mononuclear EPR-active Mo(V) complexes containing eight-coordinate Mo. As expected, W shows distinctly less reactivity than Mo in S → M redox processes. The ability of S 2− ligands to act as donors and Mo and W atoms to act as acceptors of electron density has also been exploited in the synthesis of new heteronuclear “thiocubane” clusters.

Preparation, characterization, and chemistry of activated cobalt

Preparation de microparticules de Co a partir des sels en solutions de naphtalenures le glyme. Activite pour la methanation et les reactions de Fischer-Tropsch

Metal complexes of sulfur-nitrogen chelating agents. Part 12. The chemistry of nickel(II), palladium(II), cobalt(II) and copper(II) complexes of N2S2 and N3S2 donor systems

Nickel(II), palladium(II), cobalt(II) and copper(II) complexes of the ligandN,N′-1,2-propane-bis(methyl 2-amino-cyclopent-1-ene-dithiocarboxylate) (H2L1),N,N′-1,3-propane-bis(methyl 2-aminocyclopent-1-ene-dithiocarboxylate) (H2L2) andN,N′-[bis(methyl 2-aminocyclopent-1-ene-dithiocarboxylate)] diethylenetriamine (H2L3) have been synthesised. Both H2L1 and H2L2 form complexes of the type ML, and all but the copper(II) complexes, are square planar. In the copper(II) complexes tetrahedral distortion is significantly more with CuL2. From H2L3 square planar complexes of the type [M(HL3)X] (M=Ni, X=Cl, Br, I or SCN; M=Pd, X=Cl or Br) have been obtained in which the donor unit involved is N2SX. The composition of the cobalt(II) and copper(II) complexes is [M(H2L3)X2] (X=Cl or Br) which contain the chromophore [MN3X2].

Chemistry of cobalt(1+) and Co(ligand)n+ with mono- and bi-substituted n-butanes in the gas phase: using a simple "ligand competition" model and collision-induced dissociation analysis to provide insights into product structures

Chemistry of cobalt(1+) and Co(ligand)n+ with mono- and bi-substituted n-butanes in the gas phase: using a simple "ligand competition" model and collision-induced dissociation analysis to provide insights into product structures

The co-ordination chemistry of divalent cobalt, nickel, and copper. Part 10. Characterisation and stability constants of nickel(II) species isolated from a mixed-ligand solution: crystal structure of tris(1,2-diaminoethane)nickel(II) bis(pyridine-2,6-dicarboxylato)nickelate(II) tetrahydrate

The complexes, Ni(pydca)(en)·2H2O (1), Ni(pydca)(en)3·2H2O (2), and Ni(pydca)(en)1.5·2H2O (3) were isolated from solutions of nickel(II), pydca, and en (pydca = pyridine-2,6-dicarboxylate, en = 1,2-diaminoethane). Spectral and magnetic data indicate that species (1) and (2) are octahedral and can be formulated as [Ni(pydca)(en)(H2O)]·H2O and [Ni(en)3][pydca]·2H2O, respectively. The structure of (3) was shown by Patterson and Fourier methods to be in accordance with the formula [Ni(en)3][Ni(pydca)2]·4H2O, with a= 9.395(5), b= 10.924(5), c= 15.662(8)Å, α= 70.95(2), β= 101.36(2), γ= 104.91(2)°, Z= 2, triclinic, and space group P. Heating (1) gave a compound with the empirical formula Ni(pydca)(en). Infrared and magnetic data indicate that this species is monomeric and five-co-ordinate. A compound with the same empirical formula, Ni(pydca)(en), was obtained by heating (3), but spectral data and a magnetic moment of 3.40 B.M. for this product suggest the formula [Ni(en)2][Ni(pydca)2], containing [Ni(en)2]2+ with Cs symmetry. A plot of complex-ion concentrations as a function of Ni : en ratio in solution was derived from measured stability constants and was used to explain the stepwise isolation of species (1), (3), and (2).