Heterobimetallische Komplexe mit Chelatliganden aus mehrzähnigen Aminen und 1,1-Bis(diphenylphosphan)ethen

Heterobimetallic Complexes with Chelate Ligands from Multidentate Amines and 1,1-Bis(diphenylphosphine)ethene By an addition reaction of bidentate amines Me₂N(CH₂)_nNH₂ (n = 2, as-4C2N; 3, as-5C2N) and vinylidene derivatives with an activated double bond CH₂ = C(PPh₂)₂M(CO)₄ (M = Cr, Mo, W) were synthesized in dichlormethane unsymmetrical chelate ligands of the type as-4C2N (or as-5C2N)PPM(CO)₄. They gave with divalent salts M′Y₂ (Y = ac, M′ = Cu, Ni. Y = Cl, M′ = Zn, Cd, Hg) the coloured bimetallic complexes M′Y(as-4C2N) (or as-5C2N)PPM(CO)₄ which were characterized by means of IR-, UV/VIS spectroscopic and ¹H, ¹³C and ³¹P NMR measurements. The molecular structures of the complexes Cuac₂(as-5C2N)PPCr(CO)₄, I and that of CdCl₂(as-4C2N)PPCr(CO)₄, II , were acertained by results of single crystal X-ray determinations. In the crystals of I—II , the coordination polyhedron of each chromium(0) central atom containing two phosphorous donor atoms in a four-membered chelate ring and four terminal CO ligands is octahedrally distorted. This coordination sphere is connected at the carbon ring atom via a methylen chain group (spacer) with the bidentate amine ligand, which has a secondary and a tertiary nitrogen donor atom. Both nitrogen atoms are coordinated with the Cuac₂ under formation of a new kind of [4 + 2]-coordination in a trischelate complex. The six-membered diamine chelat ring in I has a chair-like conformation. The chromium-cadmium complex II is dimer from which the Cd central atoms obtain the rare coordination number of five. The related five-membered diamine chelate ring has δ conformation.     

Speciation of chromium in waste waters by coupled column ion chromatography-inductively coupled plasma mass spectrometry

An application of coupled column ion chromatography (IC)-inductively coupled plasma mass spectrometry (ICP-MS) is presented for speciation of chromium in waste waters. By coupling an anion column with a cation column, both the cationic Cr(III) and anionic Cr(VI) species can be analyzed with detection limits below 0.5 μg/1. The separation of the interfering ions (chloride, chlorate, perchlorate, sulphate, sulphite, sulphide, thiosulphate, carbonate, cyanide and some organic compounds) from the chromium peaks is discussed, and the use of different chromium isotopes for data acquisition is compared. Based on the results, m/z 52 was considered as an ideal isotope for speciation of chromium in waste waters by the coupled column IC-ICP-MS, because it did not suffer from polyatomic interferences and due to the high sensitivity for chromium. The analysis of the waste water samples should be performed as soon as possible after sampling according to the stability tests of the species.     

铬与健康

对铬与人体健康的关系进行了综述，主要内容包括：三价铬的作用、六价铬的作用和环境中的铬。     

铬(Ⅲ)含β一二酮混合配体配合物的合成和表征

首次合了五种Cr(β-dik)Cl_2py_2型(其中β-dik分别为乙酰丙酮、苯甲酰丙酮、三氟乙酰丙酮、2—噻吩甲酰三氟丙酮、二苯甲酰甲烷)和一种Cr(pmbp)Cl_2(thf)混合配体配合物、一种Cr(pmbp)_3配合物。并对上述化合物进行了电子光谱、红外光谱等的表征工作。     

Trimethylsilylcyclopentadienylchromium(III) complexes with diphenyl-2-pyridylphosphine: synthesis, structural characterisation and catalytic behaviour of [(C6H5)2PC5H4NH][(η-Me3SiCp)CrCl3]

Reaction of CrCl₃ with LiCpSiMe₃ in THF leads to the formation of a solvated intermediate, [(η⁵-Me₃SiCp)CrCl₂(THF)], which in turn reacts with diphenyl-2-pyridylphosphine to yield the complex [(C₆H₅)₂PC₅H₄NH][(η⁵-Me₃SiCp)CrCl₃] (1) in 66% yield. As a secondary product was isolated the neutral complex [(η⁵-Me₃SiCp)CrCl₂{(C₆H₅)₂PC₅H₄N}] (2) in 5% yield. The structure of complex 1 has been determined by single crystal X-ray diffraction. In the anion the metal centre shows a pseudo-octahedral geometry with the centroid of the trimethylsilylcyclopentadienyl ligand occupying the centre of three octahedral sites, and three chloride atoms completing the co-ordination sphere. Complex 1 in the presence of MAO leads to the formation of an active catalyst for the polymerization of ethylene.     

Crystal structure of cobalt molybdate hydrate CoMoO4·nH2O

We have determined the crystal structure of the title compound, which has a triclinic cell with cell parameters of , , , α=76.617°, β=84.188°, γ=74.510° and space group . The crystal structure suggests the chemical formula CoMoO₄·3/4H₂O. The structure consists of MoO₄ tetrahedra and CoO₆ octahedra, confirming the earlier X-ray absorption near-edge spectroscopic (XANES) investigation on the hydrate. The comparison of the crystal structures of the hydrate and the α-,β-, and hp-phases shows that the hydrate exhibits metal cation coordinations similar to those of the β-phase, but had arrangements of CoO₆ and MoO_n polyhedra similar to those of the hp-phase.     

Neue neutrale und kationische Mono‐Aziridin‐Komplexe des Typs [CpMn(CO)2Az], [CpCr(NO)2Az]+ und [(Ph3P)(CO)4ReAz]+ über CO‐, Hydrid‐ und Chlorid‐Abspaltungsreaktionen

Novel Neutral and Cationic Mono‐Aziridine Complexes of the Type [CpMn(CO)₂Az], [CpCr(NO)₂Az]⁺, and [(Ph₃P)(CO)₄ReAz]⁺ via CO‐, Hydride‐, and Chloride‐Elimination Reactions The monoaziridine complexes 1 — 5 are obtained by three differently induced substitution reactions. The photolytically induced CO substitution reaction of [CpMn(CO)₃] with 2, 2‐dimethylaziridine leads to the neutral N‐coordinate aziridine complex [Cp(CO)₂Mn{$\overline{N(H)CMe₂C}$ H₂}] ( 1 ). The protonation of [(Ph₃P)(CO)₄ReH] with CF₃SO₃H and consecutive treatment with 2, 2‐dimethylaziridine or 2‐ethylaziridine gives the salt‐like aziridine complexes [(Ph₃P)(CO)₄Re{$\overline{N(H)CMe₂C}$ H₂}](CF₃SO₃) ( 2 ) or [(Ph₃P)(CO)₄Re{ H₂}](CF₃SO₃) ( 3 ) by hydride elimination reactions. The like‐wise salt‐like complexes [Cp(NO)₂Cr{$\overline{N(H)CMe₂C}$ H₂}](BF₄) ( 4 ) and [Cp(NO)₂Cr{ H₂}](CF₃SO₃) ( 5 ) are synthesized from [CpCr(NO)₂Cl] by chloride elimination with AgX (X = BF₄, CF₃SO₃) in the presence of 2, 2‐dimethylaziridine or 2‐ethylaziridine, respectively. As a result of X‐ray structure analyses, the metal atoms are trigonal pyramidally ( 1, 4, 5 ) or octahedrally ( 2, 3 , cis‐position) configurated; the intact three‐membered rings coordinate through the distorted tetrahedrally configurated N atoms. All compounds 1‐5 are stable with respect to the directed thermal alkene elimination to give the corresponding nitrene complexes; the IR, ¹H‐ and ¹³C{¹H}‐NMR, and MS spectra are reported and discussed.     

Mixed-metal cluster chemistry. 26 . Proclivity for “all-terminal” or “plane-of-bridging-carbonyls” ligand disposition in tungsten-triiridium clusters

Reaction of WH(CO)₃(η-C₅Me₅) with IrCl(CO)₂(4-H₂NC₆H₄Me) affords WIr₃(μ-CO)₃(CO)₈(η-C₅Me₅) in low yield. A structural study reveals a WIr₂-centred plane of bridging carbonyls, in contrast to the crystal structure of WIr₃(CO)₁₁(η-C₅H₅) (all-terminal carbonyl distribution). DFT calculations reveal an increasing proclivity to adopt an all-terminal CO disposition for clusters MIr₃(CO)₁₁(η-C₅H₅) in the gas phase on proceeding from M=Cr to Mo and then W, consistent with structural studies in the solid state for which the tungsten-containing cluster is the only all-terminal example. Increasing electron donation from the ligands in the tungsten system (either from phosphine substitution or cyclopentadienyl permethylation) suffices to impose a plane of bridging carbonyls in the ground state structure. ¹³C NMR fluxionality studies reveal that CO exchange mechanism(s) for WIr₃(CO)₁₁(η-C₅H₅) and the related tetrahedral cluster W₂Ir₂(CO)₁₀(η-C₅H₅)₂ are very fast and involve all carbonyls on the clusters. DFT calculations on MIr₃(CO)₁₁(η-C₅H₅) (M=Cr, Mo) substantiate a ‘merry-go-round’ mechanism for carbonyl scrambling in these systems, a result which is consistent with the scrambling behaviour seen in the NMR fluxionality studies on the W-containing congener.     

Synthesis and electrochemistry of Group 6 tetracarbonyl (N,N′-bis(ferrocenylmethylene)ethylenediamine)metal(0) complexes

Thermal substitution reaction of Cr(CO)₄(η^2:2-1,5-cyclooctadiene), Mo(CO)₄(η^2:2-norbornadiene), and W(CO)₅(η²-bis(trimethylsilyl)ethyne) with N,N′-bis(ferrocenylmethylene)ethylenediamine (bfeda) yields M(CO)₄(bfeda) complexes which could be isolated from the reaction solution and characterized by elemental analysis, MS, IR, and NMR spectroscopy. In the case of tungsten, W(CO)₅(bfeda) is formed as intermediate and then undergoes the ring closure reaction yielding the ultimate product W(CO)₄(bfeda). The electrochemical behavior of the M(CO)₄(bfeda) complexes was studied by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in dichloromethane with tetrabutylammonium tetrafluoroborate as electrolyte. Constant potential electrolysis of the complexes was performed successively at their peak potentials at 0 °C in their CH₂Cl₂ solution and the electrolysis was followed by in situ recording the electronic absorption spectra in every 5 mC. In the electrolysis of Cr(CO)₄(bfeda), the central Cr(0) is oxidized first and electrolysis continues with oxidations of two ferrocenyl groups until the end of totally three moles of electron passage per mole of complex. In the electrolysis of Mo(CO)₄(bfeda) and W(CO)₄(bfeda) the first oxidation occurs on the central atom forming a short-lived species which undergoes an intramolecular one-electron transfer and is reduced back to M(0) while one of the ferrocene units is oxidized to the ferrocenium cation at the same time. This indicates that the electron is transferred from iron to the central metal atom.     

丁基罗丹明B—钼酸盐光度法连续测定铈和钪

在聚乙烯醇（ＰＶＡ）存在下，丁基罗丹明Ｂ（ＢＲＢ）分别与铈钼、钪钼杂多酸络阴离子形成离子缔合物，其最大吸收均位于５７０ｎｍ，表面摩尔吸光度分别为εＣｅ＝３．９６×１０＾６Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，εＳｃ＝４．７１×１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，服从比耳定律范围分别为０－２４μｇ／Ｌ Ｃｅ和０－６０μｇ／ＬＳｃ，测定极限为Ｃｅ１．０μｇ／Ｌ（ｎ＝１２）和Ｓｃ１．９μｇ／Ｌ（ｎ＝１０），对