Coordination chemistry of gold(II) with amidinate,thiolate and ylide ligands

Various reagents such as Cl₂, Br₂, I₂, benzoyl peroxide and CH₃I add to the dinuclear gold(I) amidinate complex [Au₂(2,6-Me₂Ph-form)₂] to form oxidative-addition gold(II) metal–metal bonded complexes. The gold–gold distance in the dinuclear complex decreases upon oxidative-addition with halogens from 2.7 to 2.5 Å, similar to observations made with dithiolate and ylide ligands. The sodium salt of the guanidinate Hhpp ligand, Hhpp = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine reacts with (THT)AuCl in THF or CH₂Cl₂ to form a Au(II) complex, [Au₂(hpp)₂Cl₂], either by solvent oxidation or disproportionation of the Au(I) to Au(II) and the metal. Density functional theory (DFT) and MP2 calculations on [Au₂(hpp)₂Cl₂] find that the highest occupied molecular orbital (HOMO) is predominately hpp and chlorine-based with some Au–Au δ* character. The lowest unoccupied molecular orbital (LUMO) has metal-to-ligand (M–L) and metal-to-metal (M–M) σ* character (approximately 50% hpp/chlorine, and 50% gold). The charge-transfer character of the deeply colored solutions is observed in all the oxidative-addition products of the dinuclear gold(II) nitrogen ligands. This contrasts with the colors of the gold(II) ylide oxidative-addition products which are pale yellow. The colors of the crystalline gold(II) nitrogen complexes are dark orange to brown. This review will focus on the chemistry of gold(II) with nitrogen ligands and compare this with the well reviewed chemistry of gold(II) thiolate and ylide complexes.     

Syntheses and crystal structures of three structurally similar dinuclear silver(I) complexes

Three terephthalato-bridged dinuclear silver(I) complexes with the formulae Ag₂(5map)₄(tphth), [Ag₂(6map)₄(tphth)] · 2H₂O, and [Ag₂(4map)₄(tphth)] · 2H₂O (5map = 5-methyl-2-aminopyridine, 6map = 6-methyl-2-aminopyridine, 4map = 4-methyl-2-aminopyridine, tphth = terephthalate), have been synthesized and characterized by elemental analysis and single crystal X-ray diffraction. The Ag atom in each of the complexes is three-coordinate in a trigonal geometry with one carboxylate O atom and two pyridine N atoms. The characteristic difference among the complexes is the positions for the methyl groups of the aminopyridine ligands. The crystals of the complexes are stabilized by intermolecular N–H···O and O–H···O hydrogen bonds. Electronic supplementary material  The online version of this article () contains supplementary material, which is available to authorized users.     

Substituted Bisphosphanylamines as Ligands in Gold(I) Chemistry – Synthesis and Structures

Dimethyl 5‐aminoisophthalate, which is a building block of amino‐substituted tetralactam macrocycles, was used as ligand in gold(I) chemistry to form model complexes for macrocyclic gold compounds. Reaction of dimethyl 5‐aminoisophthalate with chlorodiphenylphosphine gave the diphosphine compound dimethyl 5‐[N,N‐bis(diphenylphosphanyl)amino]isophthalate (dmbpaip). This compound can further be reacted with [AuCl(tht)] (tht = tetrahydrothiophene) to give the dinuclear complex [Au₂Cl₂(dmbpaip)]. In contrast, treatment of dmbpaip with [Au(tht)₂]ClO₄ resulted in the ionic compound [Au₂(dmbpaip)₂](ClO₄)₂ in which the cation forms an eight‐membered Au₂P₄N₂ heterocycle. In both gold(I) compounds Au···Au interactions are observed. All new compounds were characterized by single‐crystal X‐ray diffraction.     

The Effect of Hard and Soft Donors on Structural Motifs in (Isocyanide)gold(I) Complexes

Treatment of the (isocyanide)gold(I) species LAuCl (L=^tBuNC, 2,6‐Me₂C₆H₃NC) with 4‐mercaptobenzoic acid in the presence of NaOMe yields the complexes [Au(4‐SC₆H₄CO₂H)L] in good yield. Reaction of LAuCl with 2‐HSQn (Qn=quinoline) and 2‐HSPy (Py=pyridine) under the same conditions provides the thiolato compounds [Au(2‐SQn)L] and [Au(2‐SPy)L], respectively. A structural investigation of the pyridylthiolato compound revealed chains of molecules with alternating medium and long Au−Au interactions. Treatment of this compound with HBF₄ results in the cationic species [Au(2‐HSPy)(2,6‐Me₂C₆H₃NC)]⁺ as the BF₄⁻ salt. The same product is obtained on reaction of [AuCl(2,6‐Me₂C₆H₃NC)] with AgOTf followed by HSPy. Treatment of the gold(I) halide compounds LAuCl (L=^tBuNC, 2,6‐Me₂C₆H₃NC) with potassium 1,3,4‐thiadiazole‐2,5‐dithiolate (KSSSK) leads to the isolation of dinuclear thiolatogold complexes [(AuL)₂(SSS)]. These products go on to form insoluble polymers through loss of isocyanide on standing in solution. A single crystal of [{Au(^tBuNC)}₂(SSS)] was obtained and the subsequent structural analysis revealed one of the most complicated networks known based solely on aurophilic interactions. A good comparison to the ‘soft' S‐donation of the thiolato ligands was provided by the synthesis of a number of nitratogold(I)complexes with the anion bound through the ‘hard' O‐donor. Reaction of ⁱPrNC and CyNC with Au(tht)Cl provided the complexes [AuCl(ⁱPrNC)] and [AuCl(CyNC)], respectively. These compounds were found to yield the respective nitrato species [Au(NO₃)ⁱPrNC)] and [(Au(NO₃)(CyNC)] on treatment with AgNO₃. The nitrato complexes yielded single crystals enabling a structural investigation to be carried out. While [Au(NO₃)(CyNC)] has a more conventional structure with dimers aligned into strings with alternating short and long aurophilic bonding, [Au(NO₃)(ⁱPrNC)] has a unique structure based on strings of alternating, corner‐sharing Au₆ and Au₈ units with short Au−Au contacts in edge‐sharing Au₃ triangles.     

Diphosphines and pyrazole/pyrazolate-type ligands as building blocks in luminescent Au(I) complexes

A series of gold(I) complexes containing diphenylphosphine bridging ligands, dppm, dppe, dpephos, dbfphos and biphep and co-ligands of the type pyrazole have been synthesized. The X-ray crystal structures of [Au₂(μ-dpephos)(μ-pz^2CH3)][PF₆], [Au₂(μ-dbfphos)(μ-pz^2CH3)][PF₆], and of the starting compound [Au₂Cl₂(μ-biphep)] indicate that the structural and stoichiometric characteristics of the new complexes depend on the diphosphine ligand. The three complexes show Au?Au contacts between 3.27 Å and 3.30 Å, with that of the biphep compound being the shortest. Digold (I)-diphosphine derivatives with a bridging pyrazolate ligand are obtained in all cases, except when [Au₂Cl₂(μ-biphep)] is used as starting material. Surprisingly, in this case, two monodentate neutral pyrazole ligands are attached to the gold atoms. The new complexes are luminescent in the solid state at 77 K and in solution both at room temperature and 77 K. Low energy emission bands related to the presence of Au?Au interactions have been identified in some of the compounds in the solid state and/or in solution.     

Development of versatile and silver-free protocols for gold(I) catalysis

The use of a versatile N‐heterocyclic carbene (NHC) gold(I) hydroxide precatalyst, [Au(OH)(IPr)], (IPr=N,N′‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene) permits the in situ generation of the [Au(IPr)]⁺ ion by simple addition of a Brønsted acid. This cationic entity is believed to be the active species in numerous catalytic reactions. ¹H NMR studies in several solvent media of the in situ generation of this [Au(IPr)]⁺ ion also reveal the formation of a dinuclear gold hydroxide intermediate [{Au(IPr)}₂(μ‐OH)], which is fully characterized and was tested in gold(I) catalysis.     

Synthesis and structure of [Ni(dien)2]3[W4S4(CN)2]·20H2O and [Cu(dien)(Hdien)]2[W4S4(CN)12]·8H2O

[Ni(dien)₂]₃[W₄S₄(CN)₁₂]·20H₂O and [Cu(dien)(Hdien)]₂[W₄S₄(CN)₁₂]·8H₂O were obtained by evaporating water-ammonia solutions containing K₆[W₄S₄(CN)₁₂]·2H₂O·2CH₃OH, diethylene triamine, and NiCl₂·6H₂O or CuCl₂·6H₂O. The crystals of the complex compounds were obtained within 3 days. The complex compounds were characterized by IR spectroscopy and by XRD and elemental analysis. XRD data for the complex [Ni(dien)₂]₃[W₄S₄(CN)₁₂]·20H₂O are: triclinic system, , a = 14.671(2) Å, b = 16.448(3) Å, c = 19.814(3) Å, α = 67.841(3)°, β = 68.996(3)°, γ = 67.527(3)°, V = 3961.6(11) ų, Z = 2; for the complex [Cu(dien)(Hdien)]₂[W₄S₄(CN)₁₂]·8H₂O: monoclinic system, C2/c, a = 37.4290(1) Å, b = 17.7370(1) Å, c = 25.7370(2) Å, β = 105.3840(2)°, V = 16474.02(16) ų, Z = 12. Original Russian Text Copyright ? 2005 by I. V. Kalinina, D. G. Samsonenko, Z. A. Starikova, A. A. Korlyukov, J. Lipkowski, V. P. Fedin, and M. Yu. Antipin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 1, pp. 139–148, January–February, 2005.     

Gold Ion–Angiotensin Peptide Interaction by Mass Spectrometry

Stimulated by the interest in developing gold compounds for treating cancer, gold ion–angiotensin peptide interactions are investigated by mass spectrometry. Under the experimental conditions used, the majority of gold ion–angiotensin peptide complexes contain gold in the oxidation states I and III. Both ESI-MS and MALDI-TOF MS detect singly/multiply charged ions for mononuclear/multinuclear gold-attached peptides, which are represented as [peptide + a Au(I) + b Au(III) + (e - a -3b) H]^e+, where a,b ≥ 0 and e is charge. ESI-MS data shows singly/multiply charged ions of Au(I)-peptide and Au(III)-peptide complexes. This study reveals that MALDI-TOF MS mainly detects singly charged Au(I)-peptide complexes, presumably due to the ionization process. The electrons in the MALDI plume seem to efficiently reduce Au(III) to Au(I). MALDI also tends to enhance the higher polymeric forms of gold-peptide complexes regardless of the laser power used. Collision-induced dissociation experiments of the mononuclear and dinuclear gold-attached peptide ions for angiotensin peptides show that the gold ion (a soft acid) binding sites are in the vicinity of Cys (a soft ligand), His (a major anchor of peptide for metal ion chelation), and the basic residue Arg. Data also suggests that the abundance of gold-attached peptides increases with higher gold concentration until saturation, after which an increase in gold ion concentration leads to the aggregation and/or precipitation of gold-bound peptides.     

[Cu2(μ-(3,4,5-meo-ba)2bn)(μ-I)2]n, a new 1D polymeric copper(I) chain Synthesis, crystal structure, spectral and thermal studies

New 1D-chain copper(I) complex [Cu₂(μ-(3,4,5-MeO-ba)₂bn)(μ-I)₂] _n (1), where (3,4,5-MeO-ba)₂bn = N,N′-bis(3,4-dimethoxybenzylidene)-butane-1,4-diamine, involving a new bidentate Schiff-base containing a flexible spacer (=N–C–C–C–C–N=) has been synthesized and characterized by elemental analyses (CHN) and FT-IR spectroscopy. The crystal structure of 1 was determined from single-crystal X-ray diffraction analyses and shows the (3,4,5-MeO-ba)₂en acts as a bridging ligand with the nitrogen atoms of the two imine functions and leading to the dinuclear [Cu₂((μ-(3,4,5-MeO-ba)₂en)] groups. Such dinuclear [Cu₂((μ-(3,4,5-MeO-ba)₂en)] groups are bridged by two iodine anions [(μ-I)₂] to form a neutral 1D-chain copper(I) iodide coordination polymer. The coordination polyhedron about the copper(I) center in 1 is best described as a distorted trigonal planar. Thermogravimetric analyses reveal the thermal stability and decomposition pattern of 1.     

Syntheses and Crystal Structures of Copper(II) and Silver Complexes with 5‐Methyl‐1‐(4‐Methylphenyl)‐1,2,3‐Triazol‐4‐Carboxylic Acid

Two novel complexes [Cu L ₂(MeOH)] ( 1 )and [Ag₂ L (H L )₂(MeOH)] ( 2 ) ( L = 5‐methyl‐1‐(4‐methylphenyl)‐1,2,3‐triazol‐4‐carboxylic acid) were synthesized and characterized by elemental analysis, IR and X‐ray diffraction. Complex 1 is a mononuclear structure; the molecules were assembled into an infinite 2–D supramolecular by the C–H···O weak interactions. Complex 2 is a centrosymmetric dinuclear structure with bis(unidentate) carboxylato co‐ordination mode, and the molecules were assembled into 2–D layers by C–H···O and O–H···O weak interactions.     

Synthesis and characterization of 2-phenylaniline cyclopalladated complexes

Reaction of the dinuclear complex [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}Cl]₂ (1) with ligands (L = 4-picoline, sym-collidine) gave the six-membered palladacycles [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}Cl(L)] (2). The complex 1 reacted with AgX (X = CF₃SO₃, BF₄) and bidentate ligands [L–L = phen (phenanthroline), dppe (bis(diphenylphosphino)ethane), bipy(2,2′-bipyridine) and dppp (bis(diphenylphosphino)propane)] giving the mononuclear orthopalladated complexes [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}(L–L)] (3) [L–L = phen, dppe, bipy and dppp]. These compounds were characterized by physico-chemical methods, and the structure of [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}Cl(L)] (L = sym-collidine) was determined by single-crystal X-ray analysis.     

Supramolecular cobalt(II) complexes: syntheses,crystal structures and solvent effects

Two Co^II complexes, namely {[CoL(MeOH)(μ-OAc)]₂Co}·2MeCN·2MeOH (1) and {[CoL(EtOH)(μ-OAc)]₂Co}·3EtOH (2) (H₂L=3,3′-dimethoxy-2,2′-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol), have been synthesized and characterized by X-ray crystallography. Both complexes contain octahedral coordination geometries, comprising three Co^II atoms, two deprotonated bisoxime L²⁻ units in which four μ-phenoxo oxygen atoms form two [CoL(X)] (X = MeOH or EtOH) units, two acetate ligands coordinated to three Co^II centers through Co–O–C–O–Co bridges, and coordinated and non-coordinated solvent. Both complexes exhibit 2D supramolecular networks through different intermolecular hydrogen-bonding interactions.     

Synthesis and structural characterization of a novel trinickel cluster: {[Ni(H<Subscript>2</Subscript>L)(EtOH)]<Subscript>2</Subscript>(OAc)<Subscript>2</Subscript>Ni} · 2EtOH

A novel trinuclear Ni^II cluster, {[Ni(H₂L)(EtOH)]₂(OAc)₂Ni} · 2EtOH [H₄L:5,5′-Dihydroxy-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol], has been synthesized and structurally characterized. The X-ray crystal structure of the cluster reveals that two acetates coordinate to three nickel ions through Ni–O–C–O–Ni bridges and four μ-phenoxo oxygen atoms from two [Ni(H₂L)] units also coordinate to nickel ions. Around three nickel atoms are all octahedral geometries.     

Synthesis,crystal structures,and magnetic properties of two manganese(II) coordination polymers bearing 1,1′-biphenyl-3,3′-dicarboxylate ligands

Two Mn(II) coordination polymers, namely [Mn(bpda)] _n (1) and [Mn(bpda)(bpy)_0.5] _n (2) (H₂bpda = 1,1′-biphenyl-3,3′-dicarboxylic acid and bpy = 4,4′-bipyridine), have been synthesized from H₂bpdc, bpy, and MnSO₄·2H₂O under hydrothermal conditions. The complexes were characterized by physicochemical and spectroscopic methods, as well as by X-ray crystallography. Compound 1 possesses a 3D structure consisting of carboxylate-bridged edge-sharing Mn–O–Mn double chains. Compound 2 features a 3D open structure with a dinuclear Mn(II) secondary building unit. Magnetic susceptibility measurements of compounds 1 and 2 exhibit antiferromagnetic interactions between the nearest Mn(II), with J = –11.3 cm⁻¹ and g = 2.12 for 1, and J = –13.5 cm⁻¹ and g = 2.12 for 2.     

Temperature-dependent synthesis, crystal structures, characterizations, and DFT calculations of two new copper(II) complexes with p-fluorobenzoic acid and 2,2′-bipyridine ligands

Two new copper(II) complexes, [Cu(p-FBA)₂(2,2′-bpy)]·(H₂O) (1) and [Cu(p-FBA)(2,2′-bpy)₂]·(p-FBA)₂ (2) {p-FBA = p-fluorobenzoic acid, 2,2′-bpy = 2,2′-bipyridine} have been obtained from an identical starting mixture using temperature as the only independent variable and characterized by X-ray single crystal diffraction as well as with infrared spectroscopy, elemental analysis, and thermogravimetric analysis. The results reveal that 1 has 1D infinite chain structure formed by O–H···O hydrogen bonds, while 2 features a 0D structure. Additionally, there exist C–H···O hydrogen bonds and π–π stacking interactions in 1, forming 2D supramolecular structure. Furthermore, density functional theory (DFT) calculations of the structures, stabilities, orbital energies, composition characteristics of some frontier molecular orbitals and Mulliken charge distributions of the [Cu(p-FBA)₂(2,2′-bpy)] of 1 and [Cu(p-FBA)(2,2′-bpy)₂]⁺ cation of 2 were performed by means of Gaussian 03W package and taking B3LYP/lanl2dz basis set.     

Effects of the Au(I)–Au(I) closed‐shell attraction on the electronic and phosphorescent properties in a series of coordination compounds: A theoretical study

The Au(I)–Au(I) closed‐shell or aurophilic attraction has been the subject of interest in the experimental and theoretical chemistry fields, due to the intriguing properties associated to it. The presence of phosphorescence in “aurophilic” compounds has been addressed to a wide range of applications, but it has not yet been fully understood. A theoretical study on the electronic and phosphorescent properties of the following series of dinuclear gold complexes has been performed: [Au₂(dmpm) (i‐mnt)] ( 1 ), [Au₂(μ‐Me‐TU) (μ‐dppm)] ( 2 ), and [Au₂(μ‐G)(μ‐dmpe)] ( 3 ). Full geometry optimizations at the second‐order Møller–Plesset perturbation theory (MP2) were carried out for each of the species. These calculations made evident that, at the ground‐state geometry, the Au(I) cations allocated at the center of the ring show a short Au–Au distance below the sum of the van der Waals radii, at the range of the aurophilic attraction. An intermolecular Au(I)–Au(I) closed‐shell attraction for a pair of the systems under study is found. This attraction is comparable to that of the hydrogen bonds. The phosphorescent properties experimentally observed for this series were also characterized through ab initio techniques. The obtained results allow to fit reasonably the excitation energies with the experimental data and to identify a correlation between the strength of the Au(I)–Au(I) interaction and the phosphorescent behavior. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Three manganese(II) coordination polymers based on 1,10-phenanthroline derivatives and mono-, bi-, or trimetallic cores

Abstract  

Three Mn(II) coordination polymers based on 1,10-phenanthroline derivatives and mono-, bi-, or trimetallic cores, namely [Mn(L1)(HL1)(Cl)] (1), [Mn(1,4-ndc)(HL1)] (2), and [Mn₃(cis-chdc)₂(trans-chdc)(L2)₂] (3), where HL1 = 1-(1H-imidazo[4,5-f][1, 10]phenanthrolin-2-yl)naphthalen-2-ol, L2 = 2-(4-fluorophenyl)-1H-imidazo[4,5-f][1, 10]phenanthroline, 1,4-ndc = 1,4- naphthalenedicarboxylate and chdc = 1,4-cyclohexanedicarboxylate, have been synthesized under hydrothermal conditions. Their structures have been determined by single crystal X-ray diffraction analyses and further characterized by physico-chemical and spectroscopic methods. Compound 1 shows a one-dimensional zigzag chain structure. The neighboring chains are extended into a two-dimensional 3-connected (6,3) network by π–π interactions. Interestingly, two (6,3) networks are interpenetrated in a twofold mode. Compound 2 displays a 2D 4-connected (4,4) network structure based on dinuclear Mn(II) units. Adjacent networks are further connected through π–π interactions to form a three-dimensional supramolecular architecture. Compound 3 shows a 2D 4-connected (4,4) network structure based on trinuclear Mn(II) units. Further, the π–π interactions among adjacent networks resulted in a 3D supramolecular architecture for 3.     

Protonation of the acyclic tetraaza metallocomplex of gold(III) [Au(C9H19N4)]2+ in aqueous solution. Synthesis and crystal and molecular structure of [Au(C9H20N4)](H5O2)(ClO4)4

Protonation equilibrium has been studied for the acyclic gold(III) tetraaza metallocomplex [AuB]²⁺ [B = N, N′-bis(2-aminoethyl)-2,4-pentanediiminato(1−)] in aqueous solution. The synthetic procedure is described. The crystal and molecular structure of the protonated form of the [AuHB](H₅O₂)(ClO₄)₄ complex has been determined. Monoclinic crystals with unit cell dimensions a = 11.964(2) Å, b = 13.789(3) Å, c = 15.496(3) Å, β = 109.00(3)°, V = 2417.1(8) ų, Z = 4, ρcalc = 2.243 g/cm³, space group P2₁/n. The structure is built of nearly planar [Au(C₉H₂₀N₄)]³⁺ complex cations, (H₅O₂)⁺ cations, and [ClO₄]⁻ anions. The gold atom coordinates four nitrogen atoms of the ligand, forming a square plane. The six-membered chelate ring of the ligand is protonated at the central β-carbon atom and contains imine C=N bonds. The oxygen atoms of the perchlorate ions are hydrogen bonded to the (H₅O₂)⁺ dihydroxonium ion and to the nitrogen atoms of the NH₂ groups of the [AuHB]³⁺ cation. Original Russian Text Copyright ? 2005 by V. A. Afanasieva, L. A. Glinskaya, R. F. Klevtsova, and I. V. Mironov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 5, pp. 909–915, September–October, 2005.     

EPR spectra and structures of dinuclear copper(<Emphasis Type="SmallCaps">II</Emphasis>) complexes with acyldihydrazones of benzenedicarboxylic acids

Spacer-armed dinuclear copper(II) complexes with condensation products of isophthalic and terephthalic acid dihydrazides with salicylaldehyde and 2-hydroxyacetophenone were synthesized and studied by EPR and X-ray diffraction. The compositions and structures of most of the complexes were determined by elemental analysis, thermogravimetric analysis, and IR spectroscopy. The structure of the copper(II) complex with acyldihydrazone of salicylaldehyde and 1,3-benzenedicarboxylic acid (H₄L) with the composition [Cu₂L¹·2morph·MeOH] (morph is morpholine) was established by X-ray diffraction. The Cu^II atoms are spaced by 10.29 Å and are structurally nonequivalent. One copper cation has a square-planar coordination formed by donor atoms (2 N + O) of the doubly deprotonated acylhydrazine fragment and the N atom of the morpholine molecule. The second copper atom is additionally coordinated by a methanol molecule through the oxygen atom, so that this copper atom is in a tetragonal-pyramidal coordination with the oxygen atom in the axial position. The EPR spectra of liquid solutions of the complexes based on 1,4-benzenedicarboxylic acid acyldihydrazones and 1,3-benzenedicarboxylic acid bis(salicylidene)hydrazone at room temperature show a four-line hyperfine structure with the constant a _Cu = 54.4–67.0·10⁻⁴ cm⁻¹ (g = 2.105–2.147), which is indicative of the independent behavior of the paramagnetic centers. The EPR spectrum of a solution of the complex based on isophthalic acid and 2-hydroxyacetophenone shows the seven-line hyperfine structure corresponding to two equivalent copper nuclei (g = 2.11, a _Cu = 36.5·10⁻⁴ cm⁻¹). Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1898–1905, October, 2007.     

Gold(III) amine complexes in aqueous alkali solutions

The gold(III) 1,3-diaminopropane complex [Au(1,3-pn)(1,3-pn-H)]Cl₂ has been synthesized. Its dissociation constant has been determined: Au(1,3-pn)₂³⁺ = Au(1,3-pn-H)²⁺ + H⁺, logK _a1 = −7.03 ± 0.05 (I = 0.1 mol/L NaClO₄). Considerable spectral changes are observed for strong alkali solutions (pH 11–14) containing the monoamido forms of the gold(III) ethylenediamine, 1,3-diaminopropane, and diethylenetriamine complexes (Au(en)(en-H)²⁺, Au(1,3-pn)(1,3-pn-H)²⁺, Au(dien-H)OH⁺). These changes are attributed to the formation of the diamido species Au(en-H)₂⁺, Au(1,3-pn-H)₂⁺, and Au(dien-2H)OH⁰. The dissociation constants of the monoamido complexes have been determined: Au(en)(en-H)²⁺ (logK _a2 = −10.9 ± 0.1 at I = 0.001–0.01 mol/L NaCl); Au(1,3-pn)(1,3-pn-H)²⁺ (logK _a2 = −11.3 ± 0.1 at I = 0.1 mol/L NaCl); Au(dien-H)OH⁺ (logK _a2 = −12.4 ± 0.1 at I = 0.1 mol/L NaCl).