Synthesis and spectral properties of a new binuclear iron complex: The ion tetracyano(4-cyanopyridine) ferrate(II)-μ-cyano-pentacyanoferrate(II)

A new cyano-bridged binuclear complex of Fe(II) can be prepared by mixing pentacyano(ammine)ferrate(II) with 4-cyanopyridine at a mole ratio 2:1. IR and UV-VIS spectra, together with kinetic data on ligand substitution, point to the following structure; (NC)₅Fe-NC-Fe(CN)₄(N

-CN)^6?, both in solid state and in aqueous solution, thus demonstrating that cyanide forms a bridge between two iron atoms which is much more stable than that formed by 4-cyanopyridine.     

A binuclear tantalum(III) complex with a bridging carboxylato ligand

Ta₂Cl₆(SMe₂)₃ reacts with one equivalent of C₄H₉CO₂Li to give a complex with a bridging carboxylate ligand, Ta₂Cl₅(O₂CC₄H₉)(SMe₂)(THF)₂. The product was isolated in two crystalline forms, 1 and 2, from a THF/hexane and benzene/hexane solvent mixture, respectively. The following are the unit cell parameters, for 1: monoclinic (P2₁/n), a = 10.537(5) Å, b = 22.015(4) Å, c = 11.663(4) Å, β = 107.80(3)°, V = 2576(3) ų, and Z = 4; for 2: monoclinic (P2₁/c), a = 15.584(4) Å, b = 15.647(4) Å, c = 11.275(3) Å, β = 106.04(5)°, V = 2642(3) ų and Z = 4. The complex is a dimer with a distorted octahedra-sharing-an-edge geometry. The TaTa distances in 1 and 2 were 2.766(1) Å and 2.779(1) Å, respectively, which is somewhat longer than in previously reported Nb(III) and Ta(III) dinuclear compounds. Diamagnetism of the complex is shown by NMR. Fenske—Hall calculations, which correctly predict an electronic transition at about 16,000 cm^?1, indicate a double TaTa bond. The observed elongation of the metalmetal bond is attributed mainly to steric crowding. The complex is the first proven low-valent Ta species with a coordinated carboxylate ion.     

Synthesis and characterization of neutral ligand-bridged binuclear dialkylcobalt(III) complexes

A series of neutral ligand-bridged binuclear dialkylcobalt(III) chelates has been prepared. Chelate systems based on monoanions of dimethylglyoxime (dm     

Synthesis and characterisation of pentacoordinated ruthenium(II) hydrazone derivatives

Several new pentacoordinated ruthenium(II) compounds, Ru(PPh₃)₂L, of Schiff bases LH₂ are reported. The Schiff bases used have been derived from isonicotinoyl hydrazone and β-diketones or salicylaldehyde, or azines and mixed azines obtained from salicylaldehyde, benzoylacetone or 2-hydroxyacetophenone. These new compounds are highly coloured crystalline solids, stable and monomeric in toluene. They readily absorb carbon monoxide gas to give a carbonyl derivative of the type Ru(PPh₃)₂CO(L) in quantitative yields.     

The isolation and X-ray structure of a complex between lithium picrate and dibenzo-36-crown-12

The crystal structure of 2Li picrate.dibenzo-36-crown-12.2H₂O was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystalli     

Synthesis and structure of the new heteronuclear palladium-mercury cluster

Interaction of the tetra-nuclear phosphinecarbonyl complex of zero-valent palladium, Pd₄(CO)₅(PEt₃)₄ (I), with a four-fold excess of 8-(α-bromomercuryethyl)quinoline gives a new neutral heteronuclear cluster Pd₄Hg₂Br₂(CO)₄(PEt₃)₄ (IV). The structure of (IV) was determined by an X-ray analysis. The molecule of (IV) contains a “butterfly” Pd₄(μ₂-CO)₄(PEt₃)₄ moiety, whose triangular “wings” are capped by Hg atoms bonded also to bromo-ligands. The metal Hg₂Pd₄ polyhedron consists of two heteroatomic Pd₃Hg tetrahedra with a common PdPd edge. The IR- and ³¹P-NMR spectra of (IV) were also studied.     

The isolation and x-ray crystal structure of a complex between sodium hexafluorophosphate and dibenzo-36-crown-12

The crystal structure of 2NaPF₆·dibenzo-36-crown-12 was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystallises in the monoclinic system, space group P2₁/n with cell constants of a = 14.189(2), b = 9.372(1), c = 16.750(3) Å, and β = 108.98(1)°. The two NaPF₆ units are each coordinated through five oxygen atoms to opposite faces of the macrocycle in a centrosymmetric manner.     

Synthesis,spectroscopic properties and crystal structure of the eight-coordinated lead complex bis[thiocyanato]-1,4,7,10,13-pentaoxacyclopentadecano lead(II)

The complex [Pbc[15]crown-5](SCN)₂ was synthesized and characterized spectroscopically (IR and FIR range) and the crystal structure was determined by X-ray diffraction on a single crystal (orthorhombic space group Pmc2₁). The structure was solved by Patterson synthesis with least-square refinement. The final R-value is 0.0328. Two Pb-atoms and two unidentical halves of the ligand were found in the asymmetric unit. For each complexed lead cation and each half of the crown ether there exists a plane of reflexion, whereby C18 and C28 are disordered. There is, however, no centre of inversion between these unidentical halves. The elementary cell comprises four units and two different types of two centrally coordinated Pb cations. Both lead cations are eight-coordinated. In the case of Pb1 the eight donor centres are the five O-atoms of the ligand and three N-atoms of the thiocyanates. For Pb2 these are five oxygens of the ligand, one nitrogen and two sulphurs of the three thiocyanates. In this complex the thiocyanate ligands occur in both ionic and covalent states. The complexation of the crown ether and the two different species of thiocyanate anions are indicated too by typical shifted absorption bands in the IR spectra. The vibrations in the FIR region can be assigned to the interactions between lead and the donor groups.     

Synthesis and characterisation of chelated (1-cyanoethyl)ruthenium(II) carbonyl complexes

The reaction between acrylonitrile and the RuH bond in HRu(CO)Cl(PPh₃)₃ results in the formation of a binuclear ruthenium(II) complex having chlorine bridges which are easily broken by sodio-derivatives of bidentate chelating ligands giving mononuclear hexacoordinated ruthenium(II) compounds. The RuC bond in these new complexes has been found to be stable towards nucleophilic reagents. The stereochemistry for these complexes has been suggested on the basis of IR, ¹H and ³¹P NMR spectra.     

Dithiophosphinates of trivalent iron,ruthenium and osmium

Dithiophosphinates of Fe(III), Ru(III) and Os(III) have been prepared and their ESR studies indicate distortion from octahedral geometry. The tetragonal and rhombic splittings and the orbital reduction factors were calculated from the experimental g values for low-spin Ru(III) and Os(III) complexes. The metal-ligand covalency increases in the order Ru < Os.     

Synthesis,characterization and crystal structure of the anilinium β-octamolybdate dihydrate

The anilinium β-octamolybdate dihydrate has been prepared in acidic aqueous solution. TG, DTG, IR and ¹H NMR techniques have been used to identify the compound. It belongs to a series of molybdates of alkyl-N- and -N,N-substituted anilinium cations. Single crystals have been analyzed by X-ray diffraction. Crystal data are: (C₆H₈N)₄[Mo₈O₂₆] · 2H₂O, space group P$\text{1}$, Z = 1, a = 10.007(1), b = 8.014(2), c = 14.645(8)Å, α = 109.81(3), β = 108.59(2), γ = 85.44(2)°, V = 1052.9(6) ų, D_o = 2.49(1), D_x = 2.52 mg m^?3, R = 0.026 and R_w = 0.031 for 5297 observed reflexions. The crystal structure consists of discrete [β-Mo₈O₂₆]^4? polyanions, two crystallographically independent (C₆H₈N)⁺ cations and one independent water molecule. Polyanions are linked to the cations and to the water molecules by hydrogen bonds of types NH…O and OH…O.     

Synthesis of chloro-carbonyl derivatives of rhenium,ruthenium, rhodium,iridium and platinum via reaction of the metal atoms with oxalyl chloride

Co-condensation of atoms of Re, Ru, Rh, Ir and Pt with oxalyl chloride gives metal chloro-carbonyl derivatives which may be used as precursors to the compounds [Re(CO)₄Cl]₂, [Ru(PMe₃)₃(CO)Cl₂], α-[Ru(CO)₃Cl(μ-Cl)]₂, [Ru(PPh₃)₂(CO)₂Cl₂], [Rh(CO)₂(μ-Cl)]₂, [Rh(PPh₃)₂COCl], [Ir(PPh₃)(CO)₂Cl₃] and cis-Pt(CO)₂Cl₂. Molybdenum atoms with oxalyl chloride give molybdenum-chloro derivatives.     

Mixed-valence electron delocalized thiocyanato bridged ruthenium dinuclear complex [{Ru(NH3)5}2SCN]4+

The thiocyanato bridged mixed-valence ruthenium dinuclear species [{Ru(NH₃)₅}2SCN]⁴⁺ has been prepared and characterized. A solvent independent, low intensity intervalence transfer band was observed in the near IR absorption spectrum suggesting a delocalized limit in the [Ru(II)-SCN-Ru(III)] unit.     

Synthesis of 2-decenedioic acid (royal jelly acid) by sequential carbonylation of butadiene catalyzed by a palladium—phosphine complex and dicobalt octacarbonyl

Carbonylation of butadiene in t-butyl alcohol catalyzed by a palladium complex gave t-butyl-3,8-nonadienoate (I). Further carbonylation of I in methanol with Co₂(CO)₈ afforded t-butylmethyl-3-decenedioate (II) as the main product. Hydrolysis and base-catalyzed isomerization of II produced E-2-decenedioic acid.     

Synthesis,X-ray structure and spectroscopy of Cu(II) complexes derived from diacetylazine dioxime

Complexes of Cu(II) with the polydentate diacetylazine dioxime ligand C₈H₁₄N₄O₂ have been synthesized by template and non-template reactions. The crystal structure of [Cu(C₈H₁₃N₄O₂)]₂[ClO₄]₂(C₂H₅OH)₂ has been determined to establish the conformation of the ligand and the coordination of the oxime function. The structural analysis shows that the nearly planar [C₈H₁₃N₄O₂]^? group behaves as a bridging tetradentate ligand. The distorted square-pyramidal coordination about each Cu atom includes three N donors from two oxime and azine and one O donor from the other oxime, the ethanol molecule occupying the apical position. A perchlorate anion is loosely bonded to Cu. The intramolecular Cu…Cu separation is 3.725(2) Å. The compound crystallizes in the centrosymmetric space group P$\text{1}$ triclinic lattice with refined lattice parameters of a = 11.963(8) Å, b = 9.784(7) Å, c = 7.501(6) Å, α = 90.69(4)°, β = 104.53(4)°, γ = 90.83(4)°, V = 849.7 ų and Z = 2. Full-matrix least-squares refinement of 1490 independent reflexions led to final discrepancy indices, R = 0.059, and R_w = 0.065. The Cu centres are highly coupled as indicated by the ESR spectrum. There is no evidence that the C₈H₁₄N₄O₂ ligand stabilizes unusual oxidation states of Cu.     

Synthesis of reduced complex oxides of molybdenum by fused salt electrolysis

Fused salt electrolysis has been used to prepare a number of reduced oxides of molybdenum with lanthanum, neodymium, and yttrium in single crystal or oriented polycrystalline form. The average valence of molybdenum in the various compounds ranged from 5.67 to 3.50. Previously unreported compounds include La₅Mo₄O₁₆ (triclinica = 5.64 Å,b = 20.7 0Å,c = 5.64 Å, α = 86.55°, β = 90.0°, γ = 93.45°); La₂Mo₂O₇ (orthorhombic,a = 12.19 Å,b = 6.05 Å,c = 3.87 Å); LaMo₂O₅ (hexagonal,a = 8.378 Å,c = 19.26 Å). In addition, single crystal specimens have been prepared of Y₂MoO₅,Ln₅Mo₃O₁₆(Ln =La, Nd) and metal atom cluster compounds of theA₂Mo₃O₈ type (A = Mg, Co, Ni, Zn).     

Synthesis and structure of tetrakis(phenylenethiourea)tellurium(II) chloride dihydrochloride,C28H26N8S4Cl4Te

Reaction of tellurium(IV) with excess phenylenethiourea(2-mercaptobenzimidazole) in aqueous methanolic hydrochloric acid leads to the formation of Te(II) complex, tetrakis(phenylenethiourea)tellurium(II) chloride dihydrochloride. The characterisation and crystal structure of the complex are reported. The crystals are monoclinic, space group P2₁/c, a = 13.939(5), b = 26.523(9), c = 4.873(2) Å, β = 100.29(4)°, V = 1772.6 ų, M = 872.4, D_c = 1.651 g cm^?3, Z = 2, F(000) = 868, μ(MoK_α) = 1.298 mm^?1. Final R = 0.055 and R_W = 0.056 for 918 independent reflections. The tellurium atom in the molecule lies at the crystallographic centre of symmetry and is bonded to four phenylenethiourea sulphur atoms in a square planar arrangement with TeS(1) = 2.678(6), TeS(2) = 2.674(5) Å and S(1)TeS(2) is 90.5(3)°. The ligand behaves as a thione. Chlorine atoms remain outside the coordination sphere of the Te and stabilise the packing arrangement in the unit cell through hydrogen bondings to nitrogen atoms.     

Studies on lactams—XXVII : Synthesis and reactions of 4-carboxy-β-lactam

Reaction of phenoxyacetyl chloride with α-carbomethoxybenzylidine-p-anisidine 1 in presence of triethylamine gave a mixture of E and Z 1-(p-anisyl)-4-carbomethoxy-3-phenoxy-4-phenyl-2-azetidinones 2 which upon hydrolysis with lithium iodide in refluxing pyridine produced the corresponding acids in the ratio of 3:1. A series of substituted β-lactams were prepared by transforming the carboxy group of the E-isomer into the acid chloride, amide, cyano, acid azide, isocyanate, urethane, urea, hydroxymethyl, aldehyde, acetoxy and methoxy groups.     

Vibrational and luminescence spectra of a new binuclear uranyl complex [(C2H5)4N]2[UO2F(NO3)2]2

The preparation, vibrational and luminescence spectra of the title compound are described. The complex has bidentate nitrate groups and bridging fluoride ions. The spectra are assigned in detail and interpreted as showing couplings between the uranyl antisymmetric stretching modes and between the nitrate modes within the dimer, the coupling energy being 17 cm^? in the former case. There is no clear evidence for electronic coupling involving the uranyl groups.