Alcohol Solvates of Lanthanoid(III) Trifluoromethanesulfonates

After vacuum dehydration, a number of hydrated trivalent lanthanoid trifluoromethanesulfonates (“triflate”, “OTf” = F₃CSO₃), when recrystallized from various alcohol (ROH) solutions, yield solvates Ln(OTf)₃ · xROH, x = 3, 5 or 6. The following have been defined crystallographically (R/Ln/x): Me/La/3;Me/Gd/6; Et/Sm/3; Et/Gd/5 iPr/Nd,Sm/3. The Me/Gd/6complex, Gd(OTf)₃ · 6MeOH is a mononuclear/ionic form [(MeOH)₆Gd(O–OTf)₂](OTf), the gadolinium environment being octacoordinate, square‐antiprismatic with the O–OTf donors quasi‐trans on different faces of the coordination polyhedron; the Et/Gd/5 complex is neutral, molecular, mononuclear [(EtOH)₅Gd(O–OTf)₃], also with an octacoordinate, square‐antiprismatic coordination sphere, derivative of that of the methanol solvate. The remainder form one‐dimensional polymeric arrays, successive lanthanoid atoms linked by (μ‐O–OTf–O′)₃ triads, at either end of a tricapped trigonal prismatic array, the ROH molecules contributing the capping atoms. A (“baseline”) (re‐)determination of the “parent” Sm(OTf)₃ · 9H₂O is also recorded.     

Synthese,Kristallstrukturen und Eigenschaften von Lanthanoid(III)-Komplexen mit 7-Oxa-bicyclo[2.2.1]heptan-2,3-dicarbonsäure

Synthesis, Crystal Structures, and Properties of Lanthanoid(III) Complexes with 7-Oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic Acid The synthesis of coordination compounds [ML(HL)(H₂O)] with M = La³⁺, Ce³⁺, Pr³⁺, Nd³⁺ and H₂L = 7-oxa-bicyclo[2.2.1]heptane-2-exo,3-cis-dicarboxylic acid ( 1 ) has been described. Results of IR spectroscopy and thermal decomposition are given. As a result of X-ray analyses, the four investigated lanthanoid(III) complexes are isotypic. Their stereochemistry approximates to the tri-capped trigonal prism with nine O atoms coordinating the metal atom. The bicyclic ligand acts as a tridentate chelating monoanion HL^? as well as a pentadentate dianion L^2? with both chelating and bridging function. One coordination place at the metal atom is occupied by a water molecule.     

Iron(III)‐Complexes Engaged in the Biochemical Processes in Seawater. II. Voltammetry of Fe(III)‐Malate Complexes in Model Aqueous Solution

Characteristics of iron(III) complexes with malic acid in 0.55 mol L^?1 NaCl were investigated by voltammetric techniques. Three iron(III)‐malate redox processes were detected in the pH range from 4.5 to 11: first one at ?0.11 V, second at ?0.35 V and third at ?0.60 V. First process was reversible, so stability constants of iron(III) and iron(II) complexes were calculated: log K₁(Fe^III(mal))=12.66±0.33, log β₂(Fe^III(mal)₂)=15.21±0.25, log K₁(Fe^II(mal))=2.25±0.36, and log β₂(Fe^II(mal)₂)=3.18±0.32. In the case of second and third reduction process, conditional cumulative stability constants of the involved complexes were determined using the competition method: log β(Fe(mal)₂(OH)_x)=15.28±0.10 and log β(Fe(mal)₂(OH)_y)=27.20±0.09.     

Synthesis and Structural Characterization of Cadmium(II) and Mercury(II) Complexes Derived from 3‐Aminoquinoline

Two novel metal complexes derived from interactions of Cd²⁺ and Hg²⁺ ions with 3‐aminoquinoline in the molar ratio 1 : 2 are reported. The synthesized and isolated metal complexes were characterized by UV/VIS, FT‐IR, ¹H‐ and ¹³C‐NMR, and ESI‐MS spectroscopic studies, and elemental analyses. FT‐IR and NMR studies confirmed that the NH₂ group remains uncoordinated in both synthesized complexes. The molecular structure of the Cd^II complex was additionally determined by X‐ray single‐crystal analysis. The Cd complex crystallizes in the triclinic centrosymmetric P$\bar 1$ space group. Moreover, the Cd^II complex exists as neutral discrete molecule and was found to show tetrahedral geometry.     

Structural Systematics for Lanthanide(III) Systems: Lattice Interactions in Salts [CoL3][Ln(dipic)3]·nH2O (L = N,N′‐Aromatic Bidentate Ligand; dipic = Dipicolinate = pyridine‐2,6‐dicarboxylate) Containing Complex Ions of D3 Symmetry

Structural characterisation of a number of hydrated solids containing chiral, kinetically inert [Co(A–A)₃]³⁺ cations (A–A = 2,2′‐bipyridine, 1,10‐phenanthroline, 4,4′‐dimethyl‐2,2′‐bipyridine) and chiral, kinetically labile [Ln(dipic)₃]^3– anions (Ln = La, Eu, Tb, Ho, Er, Lu, Y, though not for all cobalt cations; dipic = dipicolinate = pyridine‐2,6‐dicarboxylate) show a remarkable range of associations between the lattice components, though all are racemic arrays. Analysis of the structures in terms of short interatomic contacts between the components shows that, whereas numerous contacts of the heteroaromatic ligands do occur, very few define an arrangement which could be truly termed “π‐stacking” where the rings are closely parallel and atom overlaps in projection are substantial. Water is important in the highly hydrated lattice structures, not only because of hydrogen‐bonding interactions with itself and carboxylate‐O atoms but also because of its interactions with the aromatic units. The family [Co(bipy)₃][Ln(dipic)₃]·~13H₂O are essentially isomorphous for the full range of Ln plus Y (triclinic, P\bar{1} , a = 12.3, b = 14.3, c = 16.5 Å, α = 94, β = 94, γ = 108 ?, Z = 2). Among the heavier lanthanides, the potential symmetry of the anion/cation combination is realised in the trigonal space group P\bar{3} , both species lying together as an ion‐pair, disposed on the trigonal axis for [Co(phen)₃][Ln(dipic)₃]·22H₂O (Ln = Eu, Er; a = 15.2, c = 16.8 Å, Z = 2).     

Synthesen und Kristallstrukturen neuer Bromoferrate(III), Chloro‐ und Aquachloroferrate(III) mit tetraedrischer und oktaedrischer Eisenkoordination,darunter zwei Neutralkomplexe von Eisen(II) und ‐(III)

Halogeno Metallates of Transition Elements with Cations of Nitrogen‐containing Heterocyclic Bases. VIII Syntheses and Crystal Structures of Novel Bromoferrates(III), Chloro‐, and Aquachloroferrates(III) with Tetrahedral and Octahedral Iron Coordination, among them two Neutral Complexes of Iron(II) and (III) (dmpipzH₂)[Fe^IIIBr₄]₂ ( 1 ), (trienH₂)[Fe^IIIBr₄]Br ( 2 ), (dmpipzH₂)[Fe^IIICl₄]Cl ( 3 ), (dmpipzH₂)₂[Fe^III(H₂O)₂Cl₄][Fe^IIICl₄]Cl₂ ( 4 ), and (trienH₂)[Fe^III(H₂O)₃Cl₃]Cl₂ ( 5 ) crystallize from aqueous mineralic acid solutions of iron(II) halide and the organic bases (1,4‐dimethylpiperazine or triethylenediammine) in the presence of atmospheric oxygen whereas (dmpipzH₂)[FeCl₄(H₂O)₆]Cl₂ ( 6 ) was obtained under the exclusion of air. 1 , 2 , and 3 contain the known tetrahedral halogeno complexes, 4 contains a novel octahedral iron(III) complex, and in 6 a neutral binuclear iron(II) complex has been found which has not been described before. The crystal structures and the hydrogen bridging systems of the complexes are described.     

A New Germanium Complex Containing Chelating Pyridinecarboxylate Ligands: cis‐Dihydroxybis(pyridine‐2‐carboxylato‐κN1,κO2)germanium Hydrate (1 : 2) (cis‐[Ge(pyca)2(OH)2]⋅2 H2O)

A new germanium complex, cis‐[Ge(pyca)₂(OH)₂]?2 H₂O ( 1 ; pyca=pyridine‐2‐carboxylato), was synthesized by the reaction of [Ge(acac)₂Cl₂] (acac=acetylacetonato=pentane‐2,4‐dionato) with potassium pyridine‐2‐carboxylate (Kpyca) in H₂O/THF. According to the single‐crystal X‐ray diffraction analysis, each Ge‐atom of 1 is coordinated by two pyca ligands and two OH^? groups (Fig. 1). These molecules are bonded to each other via a system of H‐bonds resulting in a sheet‐like structure (Fig. 2). The complex is decomposed during heating with stepwise mass loss and formation of GeO₂ as final product (Fig. 3).     

Iron(III)‐Complexes Engaged in the Biochemical Processes in Seawater. I. Voltammetry of Fe(III)‐Succinate Complexes in Model Aqueous Solution

Fe³⁺ complexes with succinic acid, a ligand naturally present in seawater, were investigated in aqueous solutions by square‐wave and cyclic voltammetry. [Fe(suc)₂(OH)₂] and [Fe(suc)₃] were detected at potentials ?0.22 and ?0.37 V, depending on C_suc in the ranges from 0.01 to 0.07 and 0.1 to 0.5 mol L^?1, respectively. Redox processes were irreversible, first with reactant adsorption and second diffusion controlled, both accompanied by chemical step. By UV/Vis spectra formation of these complexes was confirmed and equilibrium constant Fe(suc)₂(OH)₂?Fe(suc)₃ calculated (logK_2?3=(1.14±0.15) mol^?1 L), as well as their perceptible stoichiometry. With NTA as competing ligand, conditional stability constant of [Fe(suc)₂(OH)₂] complex was calculated (β^cond=(3.1±1.3)×10²² mol^?1 L).     

Crystal Structure of Complex Tris（4,4,4—trifluoro—1—pheny1—1,3—butanedione）（1,10—phenanthroline）Europium（Ⅲ）

The complex Eu(btfa)₃ (phen) (btfa=4,4,4‐trifluoro‐1‐phenyl‐1, 3‐butanedione, phen = 1,10‐phenanthroline) has been prepared and characterized by elemental analysis, IR and UV spectroscopies. The crystal and molecular structures of the complex have been determined by X‐ray diffraction analysis. It belongs to the monoclinic crystal system, space group P2₁/c with a = 0.9700(2) nm, b = 3.7450(5) nm, c = 1.0917(3) nm, β = 92.51(2)°, V = 3.962(1) nm⁵, Z = 4, D_c = 1.639 g/cm³, μ = 1.676 mm^?1, F(000) = 1936, R₁, = 0.0388, wR₂ = 0.0775. Structure analysis shows that the europium(III) ion is coordinated to six oxygen atoms of β‐diketonate anions and two nitrogen atoms of phenanthroline molecule. The coordination polyhedron is an approximate square antiprism.     

Zur Elektronenstruktur hochsymmetrischer Verbindungen der f‐Elemente. 38 [1] Kristall‐, Molekül‐ und Elektronenstruktur von Tris(hydrotris(1‐pyrazolyl)borato)‐samarium(III)

Electronic Structures of Highly Symmetrical Compounds of f Elements. 38 [1] Crystal, Molecular and Electronic Structure of Tris(hydrotris(1‐pyrazolyl)borato)samarium(III) Tris(hydrotris(1‐pyrazolyl)borato)samarium(III) (SmTp₃) crystallizes in the space group P6₃/m (No. 176) with two molecules in the unit cell. The Sm³⁺ central ion is coordinated by nine N atoms in the shape of a tricapped trigonal prism, leading to an effective crystal field (CF) of D_3h symmetry. The underlying CF splitting pattern was extracted from the absorption and luminescence spectra run at room and low temperatures, and simulated by fitting the free parameters of a phenomenological Hamiltonian achieving an r.m.s. deviation of 9.4 cm^?1 for 58 assignments. The parameters used allow the estimation of the global ligand field strength experienced by the Sm³⁺ central ion, the insertion of SmTp₃ into empirical nephelauxetic and relativistic nephelauxetic series, and the set‐up of experimentally based nonrelativistic and relativistic molecular orbital schemes in the f range.     

Synthesis,Characterization and Magnetic Studies of μ‐Oxamido Copper (II) ‐ Chromium (III) Heterodinuclear Complexes

Three new μ‐oxamido‐bridged heterodinuclear copper (II)‐chromium (III) complexes formulated [Cu(Me₂oxpn)Cr‐(L)₂](NO₃)₃, where Me₂oxpn denotes N,N'‐bis(3‐amino‐2, 2‐dimethylpropyl)oxamido dianion and L represents 5‐methyl‐1,10‐phenanthroline (Mephen), 4,7‐diphenyl‐1,10‐phenanthroline (Ph₂phen) or 2,2′‐bipyridine (bpy), have been synthesized and characterized by elemental analyses, IR and electronic spectral studies, magnetic moments of room‐temperature and molar conductivity measurements. It is proposed that these complexes have oxamido‐bridged structures consisting of planar copper (II) and octahedral chromium (III) ions. The variable temperature magnetic susceptibilities (4.2–300 K) of complexes [Cu(Me₂oxpn)Cr(Ph₂phen)₂](NO₃)₃ (1) and [Cu(Me₂oxpn)Cr(Mephen)₂] (NO₃)₃ (2) were further measured and studied, demonstrating the ferromagnetic interaction between the adjacent chromium (III) and copper (II) ions through the oxamido‐bridge in both complexes 1 and 2. Based on the spin Hamiltonian, ? = ‐ 2J?₁ · ?₂, the exchange integrals J were evaluated as + 21.5 an^?1 for 1 and + 22.8 cm^?1 for 2.     

Self‐Assembly of Organic Chromosphere Cations with Inorganic Lanthanide(III) Complex Counterions

Hybrid complexes based on a D‐π‐A type dye p‐aminostyryl‐pyridinum cation and a lanthanide(III) complex anion were synthesized by ionic exchange reaction. Different alkyl‐substituted amino groups were used as electron donors in organic dye cations. The synthesized complexes were characterized by elemental analysis. In addition, the structural features of them were studied by single‐crystal X‐ray diffraction analysis. Their optical properties were systematically investigated by absorption and fluorescence spectroscopy.     

Oxidative Addition to Gold(I) by Photoredox Catalysis: Straightforward Access to Diverse (C,N)‐Cyclometalated Gold(III) Complexes

Herein, we report the oxidative addition of aryldiazonium salts to ligand‐supported gold(I) complexes under visible light photoredox conditions. This method provides experimental evidence for the involvement of such a process in dual gold/photoredox‐catalyzed reactions and delivers well‐defined (C,N)‐cyclometalated gold(III) species. The remarkably mild reaction conditions and the ability to widely vary the ancillary ligand make this method a potentially powerful synthetic tool to access diverse gold(III) complexes for systematic studies into their properties and reactivity. Initial studies show that these species can undergo chloride abstraction to afford Lewis acidic dicationic gold(III) species.     

Synthesis and Structural Study of Copper(I) or Silver(I) Complexes of 2,11‐Dithia‐4,5,6,7,8,9‐Hexahydro[3.3]paracyclophanes

The complexes of 2,11‐dithia‐4,5,6,7,8,9‐hexahydro[3.3]paracyclophane (dthhpcp) with Cu(I), i.e. [Cu₂I₂(dthhpcp)₂]·2H₂O 1 , or with Ag(I), i.e. [Ag(dthhpcp)(NO₃)]thf 2 and [Ag(dthpcp)(CF₃COO)] 3 , were prepared for structural study by single‐crystal X‐ray diffraction analysis. For these three complexes, dthhpcp serves as a bridging group in the polymeric structure through bridging sulfur atoms via metal, while the bonding of anion with the second metal atom forms the multi‐diminished structures. Complex 1 is a novel two‐dimensional coordination polymer composed of Cu₆ motifs, in which Cu₂I₂ formed a square planar unit to link the dthhpcp molecule. The two oxygen atoms of the nitrate anion as a bridge for two Ag atoms in complex 2 provides a three‐dimensional channel framework of silver(I) with a tetrahydrofuran molecule as a guest inside the open cavities. In contrast, the analogous reaction with silver triflouroacetate gave a complex 3 , which is composed of infinite linear chains of‐Ag‐dthhpcp‐Ag‐dthhpcp‐ along the a axis. Unit cell data: complex 1 , orthorhombic system, space group P2(1)2(1)2(1), a = 19.2982(11) Å b = 16.5661(10) Å, c = 25.3006(15) Å, β = 90°, Z = 8; complex 2 , orthorhombic system, space group Pna2(1), a = 8.8595(6) Å, b = 12.6901(9) Å, c = 19.8449(14) Å, β = 90°, Z = 4; complex 3 , monoclinic system, space group P2(1)/n, a = 8.845(3) Å, b = 20.841(6) Å, c = 11.061(3) Å, β = 107.832(6)°, Z = 4.     

Tin(IV) complexes of 2‐benzoylpyridine N(4)‐phenyl‐thiosemicarbazone: spectral characterization,structural studies and antifungal activity

Three tin(IV) complexes of 2‐benzoylpyridine N(4)‐phenylthiosemicarbazone (H2Bz4Ph) were prepared: [Sn(L)Cl₃] (1), [BuSn(L)Cl₂] (2) and [(Bu)₂Sn(L)Cl] (3), in which L stands for the anionic ligand formed upon complexation with deprotonation and release of HCl. The complexes were characterized by a number of spectroscopic techniques. The crystal structures of H2Bz4Ph and complex 3 were determined. The antifungal activity of the ligand and its tin(IV) complexes was tested against Candida albicans. The thiosemicarbazone proved to be more active than the tin(IV) complexes. Copyright © 2003 John Wiley & Sons, Ltd.     

The Structural Systematics of Protonation of Some Important Nitrogen‐base Ligands. II. Some Univalent Anion Salts of Singly Protonated Bis(2‐pyridyl)amine

Syntheses and single crystal X‐ray structure determinations are recorded for a number of normal and ‘acid’ salts of bis(2‐pyridylamine), ‘dpa’, with univalent anions, X, variously hydrated, i.e. [dpaH]X·nH₂O, and [dpaH]X·HX·nH₂O. The ‘normal’ salt arrays so characterized are for X = Br^? (n = 2, isomorphous with the previously described chloride compound) and, I^?, ClO₄^?, ‘tca^?’ (≡ Cl₃CCO₂)^? (all n = 1); acid salt arrays are described for X = NO₃^? and tca (both n = 0). In all cases except those of X = ClO₄^?, NO₃^?, there is one independent formula unit devoid of crystallographic symmetry comprising the asymmetric unit of the structure. In all cases, the proton associated with the cation is ‘chelated’ by the pair of ring nitrogen atoms, disposed ‘endo’; in the tca adducts and the nitrate salt, the total cation is disordered in each case by inversion about a real or putative inversion centre between the rings. In the perchlorate compound, the (ordered) cation lies on a crystallographic 2‐axis, as does the water molecule, and the perchlorate ion, which is disordered about such an axis; in the nitrate compound, the acid hydrogen atom is modelled as disposed on a crystallographic inversion centre between a pair of symmetry‐related nitrate groups, containing, like the Htca adduct, the [XHX]^? moiety rather than a diprotonated cation.     

Synthesis,Crystal Structure,Fluorescent and Antioxidation Properties of Cerium(III) and Europium(III) Complexes with Bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine

Two aliphatic ether Schiff base lanthanide complexes (Ln = Eu, Ce) with bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine (Bod), were synthesized and characterized by physicochemical and spectroscopic methods. [Eu(Bod)(NO₃)₃] ( 1 ) is a discrete mononuclear species and [Ce(Bod)(NO₃)₃DMF]_∞ ( 2 ) exhibits an inorganic coordination polymer. In the two complexes, the metal ions both are ten‐coordinated and the geometric structure around the Ln^III atom can be described as distorted hexadecahedron. Under excitation at room temperature, the red shift in the fluorescence band of the ligand in the complexes compared with that of the free ligand can be attributed to coordination of the rare earth ions to the ligand. Moreover, the antioxidant activities of the two complexes were investigated. The results demonstrated that the complexes have better scavenging activity than both the ligand and the usual antioxidants on the hydroxyl and superoxide radicals.     

Efficient Synthesis of 2‐(2‐Aminophenyl)‐2,3‐dihydropyridin‐4(1H)‐ones Based on a Cyclization/Ring Cleavage Procedure

(Benzyloxycarbonyl)‐protected 3,4‐benzo‐7‐hydroxy‐2,9‐diazabicyclo[3.3.1]non‐7‐enes were prepared by one‐pot cyclizations of 1,3‐bis(silyl enol ethers) with quinazolines. Subsequent hydrogenation resulted in one‐pot deprotection and rearrangement to give 2‐(2‐aminophenyl)‐2,3‐dihydropyridin‐4(1H)‐ones.     

Crystal structure and thermal study of the new hydrated cadmium-cerium(III) chloride CeCd4Cl11·13H2O

The new double-salt CeCd₄Cl₁₁·13H₂O in the ternary system CeCl₃-CdCl₂-H₂O has been prepared from aqueous solution upon evaporation at 5°C and characterized based on elemental analysis, spectroscopic data, thermal studies and X-ray powder and single-crystal diffraction. CeCd₄Cl₁₁·13H₂O crystallizes in the monoclinic space group P2₁ with a=7.667(2), b=17.351(3), c=11.970(2)Å, β=101.61(3)° and Z=2. After refinement of the structure the reliability factor R in the final cycle is 0.064. The structure can be regarded as consisting of endless double chains of CdCl₆ and CdOCl₅ octahedra and isolated tricapped triangular prisms surrounding the cerium cations. Differential scanning calorimetry showed that the title compound exhibits five endothermic anomalies interpreted from thermogravimetry. A comparison with the structure of SrCd₂Cl₆·8H₂O is proposed.