Bernardus J. A. M. van Brecht

NITROGEN REAGENTS IN METAL ION SEPARATION. XI. THE SYNTHESIS AND EXTRACTION BEHAVIOR OF A NEW NS IMIDAZOLE DERIVATIVE

A new extractant with an NS donor chromophore viz. 2-(1-ethylthiomethyl)-1-decyl imidazole (ETDIMZ) has been synthesized. Its extraction behavior towards each of Co2+, Ni2+, Cu2+, and Zn2+ in each of perchlorate, chloride and thiocyanate media in dilute acid media have been studied. Its behavior was compared with a similar pyridine derivative, viz. 2-(octylthiomethyl)-pyridine (OTMP) under comparable conditions. These behaviors have been interpreted in terms of the coordination chemistry of the metal ions. It was shown how formation constants of simple ligands, symmetry of the complex species and phase transferability can influence extraction behavior and how the above parameters can assist in the development of metal ion specific extractants.

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)

Abstract 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](ClO4)2 (M = Co, Ni and Cu) and [Co-(ppda)2] (ClO4)2(acet) (acet = acetone), had distorted octahedral chromophores. The distortion was most pronounced in [Cu(ppda)2](ClO4)2. This severe distortion was not present in octahedral [Ni(tdpa)2]-(CIO4)2. Isostructural, crystalline (MCl2)3(tdpa)12 (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[MCl4] to these complexes. The anion was found to be tetrahedral while the cation had a distorted tetrahedral chromophore. The reaction of NiBr2 with dpda produced two complexes; green αNiBr2(dpda) was isolated at room temperature while red βNiBr2(dpda) was obtained from hot solution. Characterisation data indicated αNiBr2(dpda) to have a pentacoordinate chromophore. The characterisation data for βNiBr2(dpda) was ambiguous and a crystal structure determination was performed (monoclinic crystal, space group P21/a with a = 13.871, b = 16.019, c = 9.878A, β = 95.492°, final R factor = 0.0549 and Nobs = 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 NiBr2(dpda)(dmp) (dmp = 2,2-dimethoxypropane) and NiBr2(dpda)(acet) were analogous to those of αNiBr2(dpda) and βNiBr2(dpda) respectively.

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

Abstract 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 (MX2)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 MX42− anion. Reaction of equimolar quantities of CoCl2 and depo resulted in the isolation of CoCl3(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 NiCl3(H·depo)complex could only be obtained by the addition of hydrochloric acid. The reaction of equimolar amounts of CoCl2, dmpo, and HCl yielded (H·dmpo)2[CoCl4]. 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(ClO4)2·2H2O resulted in inconclusive characterisation data. The complexes [M(dmpo)2(mecn)2](ClO4)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.

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)

Abstract 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·H2O 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 CuCl3(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 (CuCl2)3(dmpo)4; tetragonal, space group P 4 21c, a = b = 15.330(2), c = 13.992(4) A, Z = 2. The compound consisted of two penta-coordinate [Cu(dmpo)2Cl]+ cations and a tetragonally distorted CuCl42− 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 (CuBr2)3(dmpo)4.

The chemistry of uranium. Part 41. Complexes of uranium tetrahalide, with emphasis on iodide, and triphenylphosphine oxide, tris(dimethylamino)phosphine oxide or tris(pyrrolidinyl)phosphine oxide. Crystal structure of tetrabromobis[tris(pyrrolidinyl)phosphine oxide]uranium(IV)

Abstract The complexes UI4(tppo)2 (tppo=triphenylphosphine oxide), UI4(tdpo)2 (tdpo=tris(dimethylamino)phosphine oxide) and UI4(tpyrpo)2(tpyrpo=tris(pyrrolidinyl)phosphine oxide) have been prepared and IR and electronic spectra of both the solid and solutions are reported for them. The crystal structure of UBr4(tpyrpo)2 has been determined by X-ray crystallography. The compound is monoclinic, space group C2/c, with a=17.226(5), b=11.883(5), c=18.372(5) A, β=109.30(3)°; Dc=2.005(5)g cm−3. There are four molecules in the unit cell and the uranium atoms, which are trans-octahedrally surrounded by meridional bromide ions and apical oxygen atoms of the tpyrpo ligands, are in special positions on inversion centres. Selected bond lengths are: UBr 2.775(2) A, UO 2.22(1) A, PO 1.52(1) A, PN 1.62(1) A. The relative donor strengths of the three phosphine oxide ligands towards the uranium tetrahalides, as obtained from crystallographic data, are discussed. The preparation and characterization of the less common [UX3L3] complexes, where X=Cl, Br, I; Y=I, Ph4B; L=tdpo, tpyrpo and [UI(tdpo)5]I3 is discussed. Six coordinate chromophores are assigned to these complexes.

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)A, 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.

The coordination chemistry of divalent cobalt, nickel and copper. Part II. The characterisation of a mixed ligand nickel(II) species and its thermal decomposition products. The crystal structure of (pyridine-2,6-dicarboxylato)(N,N,N′,N′-tetramethyl-1,2-diaminoethane)nickel(II) dihydrate

Abstract The magnetic and spectral properties of the complex Ni(pydca)(tmen)·2H 2 O (1) and those of the thermally-derived species Ni(pydca)(tmen)·H 2 O (2) and Ni(pydca)(tmen) (3) have been studied (pydca = pyridine-2,6-dicarboxylate, tmen = N,N,N,′,N′-tetramethyl-1,2-diaminoethane). Conflicting features in the electronic spectra prevented unambiguous stereo-chemical assignments. The presence of split ν 8 (COO) and ν as (COO) infrared absorption bands in the regions 1350–1400 cm −1 and 1610–1680 cm −1 respectively suggested dissimilar co-ordination of the carboxylate groups. The structure of (1) has been determined by the heavy-atom technique and refined by least-squares. Crystals are triclinic, space group P 1 , with a = 10.806(5), b = 8.626(4), c = 9.825(5) A, α = 114.32(2), β = 91.52(2), γ = 96.67(2)°, d obs = 1.50 (by flotation), d calc = 1.51 g cm −3 and Z = 2. With N obs = 2218, the final R factor was 0.047. Complex (1) is properly formulated as [Ni(pydca)(tmen)(H 2 O)]·H 2 O with Ni in a distorted octahedral environment, being bonded to two O atoms and the N atom of pydca, the two N atoms of tmen and one water molecule. The NiN(amine) distances differ significantly but structural parameters for the two carboxylate groups agree within experimental error. The anomalous spectral splitting appears to be common to analogous species containing fully-substituted diamines. Distorted octahedral and distorted square pyramidal symmetries are assigned to (2) and (3) respectively.

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)A, 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).

The chemistry of quadrivalent lanthanoids. Part 2. Preparation and properties of cerium tetrachloride complexes and a comparison with their uranium analogues

Cerium tetrachloride complexes, viz. [CeCl4L2] and [CeCI4L] where L = a uni- or bi-dentate arsine oxide, a phosphine oxide, a sulphoxide, or an amide, have been prepared. The thermal degradation behaviour of the solids could be divided into three patterns, one of which consists of loss of a chlorine atom only. It was indicated that [CeCI4(ipae)2] could act as a substitute for the thermally unstable CeCl4 for solution studies [ipae = 1-(di-isopropylamino)ethanal]. Decomposition rate studies of solutions of [CeCl4(ipae)2] and Cs2[CeCI6] in different solvents indicated that the decomposition reaction is first order with respect to cerium(IV) and its rate is approximately proportional to the donor number of the solvent. Solutions in thionyl chloride are stable for an indefinite period. The compounds studied were compared with their uranium(IV) analogues with respect to co-ordination behaviour, i.r spectra, non-aqueous conductometric behaviour, and solvoscopic nature. The CeCl4 and UCI4 complexes proved very similar in almost all respects, except that those of cerium(IV) were more solvoscopic. Some differences between cerium(IV) and uranium(IV) can probably be explained best in terms of differences between 4f and 5f metal character rather than size differences.