Nature of the Ln-Co magnetic interactions in compounds [Ln2Co3(C5H4NPO3)6] · 4H2O with open-framework structures

The reactions of Ln(NO₃)₃ · xH₂O, CoSO₄ · 7H₂O or ZnSO₄ · 6H₂O and 2-pyridylphosphonic acid under hydrothermal conditions result in heterometallic phosphonate compounds with formula [Ln₂M₃(C₅H₄NPO₃)₆] · 4H₂O (Ln₂M₃; M = Co^II or Zn^II; Ln = La^III, Ce^III, Pr^III, Nd^III, Sm^III, Eu^III, Gd^III, Tb^III, Dy^III). These compounds are isostructural and crystallize in a chiral cubic space group I2₁3. Each structure contains the {LnO₉} polyhedra and {MN₂O₄} octahedra which are connected by edge-sharing to form an inorganic open-framework structure with a 3-connected 10-gon (10, 3) topology. The nature of Ln^III-Co^II magnetic interactions in Ln₂Co₃ is investigated by a comparison with their Ln^III-Zn^II analogues. It is found that the Ln^III-Co^II interaction is weak antiferromagnetic for Ln = Ce and ferromagnetic for Ln = Sm, Gd, Tb and Dy. In the cases of Ln = Pr, Nd and Eu, no significant magnetic interaction is observed.     

A seven-coordinate Fe compound: [Fe{O(CH2CO2)2}(H2O)2(NO3)]. Preparation, structure and magnetic properties

A seven-coordinate Fe^III complex, [Fe(oda)(H₂O)₂(NO₃)], was obtained after dissolving Fe(NO₃)₃ · 9H₂O in an aqueous solution of oxydiacetic acid (H₂oda) at room temperature. In the solid state, the Fe^III center adopts a pentagonal bipyramid geometry with an {FeO₇} core formed by a tridentate oda²⁻ and a bidentate in the equatorial plane, and two axial water molecules. Magnetic measurements and EPR spectra revealed the presence of S = 5/2 Fe^III centers with rhombic zero field splitting parameters (D = 0.81 cm⁻¹, E/D = 0.33 ). Weak antiferromagnetic interactions with J ≈ −0.06 cm⁻¹ operating between neighboring Fe ions connected through Fe-O-C-O?H-O-Fe paths are estimated using the molecular field approximation.     

Ligand-to-ligand electron transfer and temperature induced valence tautomerism in o-dioxolene chelated manganese complexes

Three polymeric o-dioxolene chelated manganese(III) complexes, {[Mn^III(H₂L¹)(Cl₄Cat)₂][Mn^III(Cl₄Cat)₂(H₂O)₂]}_∞ (1) (L¹ = N,N′-bis(2-pyridylmethyl)-1,4-butanediamine, Cl₄Cat = tetrachlorocatecholate dianion], {[Mn^III(H₂L¹)(Br₄Cat)₂][Mn^III(Br₄Cat)₂(H₂O)₂]·4DMF}_∞, (2) and {[Mn^III(H₂L²)(Br₄Cat)₂][Mn^III(Br₄Cat)₂(DMF)₂]}_∞ (3) (L² = N,N′-bis(2-pyridylmethyl)-1,6-hexanediamine, Br₄Cat = tetrabromocatecholate dianion) have been synthesized and structures were determined by X-ray crystallography. All the complexes were fully characterized by various spectroscopic techniques and their electronic properties are described. It was found that the simple protonation or deprotonation of the bridging ligand (L¹ or L²) coordinated to metal-dioxolene chromophore induce a change in the oxidation state of the coordinated dioxolene ligand without affecting the metal oxidation state. As a result, drastic change in the optical absorption properties of the complexes is observed in the visible and near-IR region as the transformation involves semiquinone-catecholate ligands. Moreover, all three complexes undergo thermally induced valence tautomerism in solution. For all the complexes, on increasing the temperature, the intensity of the lower energy Inter Valence Charge Transfer (IVCT) band at about 1930 nm increases with corresponding decrease of 600 nm band with an isosbestic point at 1820 nm due to the formation of mixed valence species Mn^II(X₄SQ)(X₄Cat)⁻ from (X = Cl or Br) by the transfer of one electron from Cat²⁻ to Mn^III center.     

Heterodimetallic Pd-based carboxylate-bridged complexes: Synthesis and structure of single-crystalline Pd-M (M = Mn, Co, Ni, Cu, Zn, Nd, Eu, Ce) acetates

A series of crystalline Pd^II-based heterodimetallic acetate-bridged complexes containing the transition (Mn^II, Co^II, Ni^II, Cu^II), post-transition (Zn^II) and rare-earth (Ce^IV, Nd^III, Eu^III) metals were synthesized starting from Pd₃(OOCMe)₆ and the complementary metal(II, III) acetates. The crystal and molecular structures of the binuclear Pd^IIM^II(μ-OOCMe)₄L (M = Mn, Co, Ni, Zn; L = H₂O, MeCN), trinuclear and tetranuclear (M = Nd, Eu) and complexes were established by X-ray diffraction.     

Synthesis and characterization of four novel mixed (porphyrinato)(phthalocyaninato) sandwich-type europium(III) complexes with [tetrakis(4-chlorophenyl)porphyrinato] and diversely substituted phthalocyaninato ligands

Four novel mixed (porphyrinato)(phthalocyaninato) rare earth double-deckers Eu^III(TClPP)[Pc(t-BuPhO₂)₄] {H₂TClPP = tetrakis(4-chlorophenyl)porphyrin, H₂[Pc(t-BuPhO₂)₄] = 1,3,10,12(11,13),19,21(20,22),28,30(29,31)-octa-tert-butyl-tetrakis[1,4]benzodioxino[2,3-b:2′,3′-k:2″,3″-t:2?,3?-e₁]phthalocyanine}, HEu^III(TClPP)[Pc(α-OC₄H₉)₈] {H₂[Pc(α-OC₄H₉)₈] = 1,4,8,11,15,18,22,25-octa-butoxy-phthalocyanine}, Eu^III(TClPP)[Pc(MeOPhO)₈]{H₂[Pc(MeOPhO)₈] = 2,3,9,10,16,17,23,24-octakis(4-methoxyphenoxy)phthalocyanine} and Eu^III(TClPP)[Pc(PhS)₈] {H₂[Pc(PhS)₈] = 2,3,9,10,16,17,23,24-octakis(benzenesulfenyl)phthalocyanine} have been prepared for the first time by treating Eu(acac)(TClPP) with corresponding metal-free phthalocyanine in refluxing 1,2,4-trichlorobenzene (TCB). Typical IR marker bands of the monoanion radical , and show strong bands at 1310, 1319, and 1318 cm⁻¹, and are attributed to pyrrole CC stretchings. The TClPP⁻ IR marker band at ca. 1270-1300 cm⁻¹ was not observed for these compounds. These facts indicate that the hole in these double-deckers is mainly localized at the phthalocyanine ring. The marker IR band for phthalocyanine monoanionradical, , appearing at ca. 1312 cm⁻¹ as a medium absorption band was not observed for HEu^III(TClPP)[Pc(α-C₄H₉)₈]. Instead, a significant peak appearing at ca. 1321 cm⁻¹ with weak intensity is assigned to the pyrrole stretching of the phthalocyanine dianion, . This suggests that both the phthalocyanine and porphyrin rings exist as dianions in mixed (porphyrinato)(phthalocyaninato) complex, . The four complexes were characterized by MS, EA, UV-Vis and IR spectra.     

Mono, di and polynuclear Cu(II)-azido complexes incorporating N,N,N reduced schiff base: syntheses, structure and magnetic behavior

Three kinds of copper(II) azide complexes have been synthesised in excellent yields by reacting Cu(ClO₄)₂ · 6H₂O with N,N-bis(2-pyridylmethyl)amine (L¹); N-(2-pyridylmethyl)-N′,N′-dimethylethylenediamine (L²); and N-(2-pyridylmethyl)-N′,N′-diethylethylenediamine (L³), respectively, in the presence of slight excess of sodium azide. They are the monomeric Cu(L¹)(N₃)(ClO₄) (1), the end-to-end diazido-bridged Cu₂(L²)₂(μ-1,3-N₃)₂(ClO₄)₂ (2) and the single azido-bridged (μ-1,3-) 1D chain [Cu(L³)(μ-1,3-N₃)]_n(ClO₄)_n (3). The crystal and molecular structures of these complexes have been solved. The variable temperature magnetic moments of type 2 and type 3 complexes were studied. Temperature dependent susceptibility for 2 was fitted using the Bleaney-Bowers expression which led to the parameters J = −3.43 cm⁻¹ and R = 1 × 10⁻⁵. The magnetic data for 3 were fitted to Baker’s expression for S = 1/2 and the parameters obtained were J = 1.6 cm⁻¹ and R = 3.2 × 10⁻⁴. Crystal data are as follows. Cu(L¹)(N₃)(ClO₄): Chemical formula, C₁₂H₁₃ClN₆O₄Cu; crystal system, monoclinic; space group, P2₁/c; a = 8.788(12), b = 13.045(15), c = 14.213(15) Å; β = 102.960(10)°; Z = 4. Cu(L²)(μ-N₃)(ClO₄): Chemical formula, C₁₀H₁₇ClN₆O₄Cu: crystal system, monoclinic; space group, P2₁/c; a = 10.790(12), b = 8.568(9), c = 16.651(17) Å; β = 102.360(10)°; Z = 4. [Cu(L³)(μ-N₃)](ClO₄): Chemical formula, C₁₂H₂₁ClN₆O₄Cu; crystal system, monoclinic; space group, P2₁/c; a = 12.331(14), b = 7.804(9), c = 18.64(2) Å; β = 103.405(10)°; Z = 4.     

Kinetic studies of the reduction of hexaaquacobalt(III) perchlorate by a cobaloxime, [Co(dmgBF2)2(H2O)2]

The reaction of with Co(dmgBF₂)₂(H₂O)₂ in 1.0 M HClO₄/LiClO₄ was found to be first-order in both reactants and the [H⁺] dependence of the second-order rate constant is given by k_2obs = b/[H⁺], b at 25 °C is 9.23 ± 0.14 × 10² s⁻¹. The [H⁺] dependence at lower temperatures shows some saturation effect that allowed an estimate of the hydrolysis constant for as K_a = 9.5 × 10⁻³ M at 10 and 15 °C. Marcus theory and the known self-exchange rate constant for Co(OH₂)₅OH^2+/+ were used to estimate an electron self-exchange rate constant of k₂₂ = 1.7 × 10⁻⁴ M⁻¹ s⁻¹ for .     

Synthesis, crystal structures and magnetic characterization of heterodinuclear CuGd and CuTb Schiff base complexes

Preparation, crystal structures and magnetic properties of new heterodinuclear Cu^IIGd^III (1) and Cu^IITb^III (2) complexes [CuLn(L)(NO₃)₂(H₂O)₃MeOH]NO₃·MeOH (where Ln = Gd, Tb) with the hexadentate Schiff-base compartmental ligand N,N′-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine (H₂L = C₁₉H₂₀N₂O₄Br₂) (0) have been described. Crystal structure analysis of 1 and 2 revealed that they are isostructural and form discrete dinuclear units with dihedral angle between the O1Cu1O2 and O1Gd1/Tb1O2 planes equal to 2.5(1)° and 2.6(1)°, respectively. The variable-temperature and variable-field magnetic measurements indicate that the metal centers in 1 and 2 are ferromagnetically coupled (J = 7.89 cm⁻¹ for 1). Crystal and molecular structure of the Schiff base ligand (0) has been also reported. The complex formation changes the conformation of Schiff base ligand molecule.     

Supramolecular assembly of coordination networks in silver(I) triple salts containing acetylenediide and some N,O-donor ligands

Five new silver(I) triple salts: (Ag₂C₂)(AgNO₃)₄(AgL¹)₂(L¹H)₂ (1), (Ag₂C₂)(AgCF₃CO₂)₂(AgL¹)₂(L¹H)_1/2 (2), [(Ag₂C₂)(AgCF₃CO₂)₄(L²)(H₂O)] · (L²H₂) (3), (Ag₂C₂)(AgNO₃)₃(AgL³)₂ (4), and [(Ag₂C₂)(AgCF₃CO₂)₄(AgL³)₂(H₂O)₂] · H₂O (5) (L¹H = nicotinic acid, L²H = isonicotinic acid, L³H = 2-pyrazinecarboxylic acid) have been synthesized by the hydrothermal method. All five compounds contain polyhedral silver(I) cages each encapsulating an acetylenediide dianion, . In 1, C₂@Ag₈ cages in the shape of bicapped trigonal prisms are interlinked by nitrate, L¹, and L¹H ligands into a three-dimensional architecture. In 2, silver(I) columns generated from fusion of triangulated dodecahedra are linked by L¹ into a layer structure. Compound 3 provides a rare example of a (L²H₂)⁺-pillared three-dimensional structure via hydrogen bonding. In 4, nitrate ligands together with L³ link the C₂@Ag₇ cages into a three-dimensional architecture. Compound 5 also exhibits a three-dimensional architecture generated from trifluoroacetate and L³-linked C₂@Ag₈ cages.     

N,N′-Bis(3-methoxysalicylidene)propane-1,2-diamine mononuclear 4f and heterodinuclear Cu-4f complexes: Synthesis, crystal structure and electrochemical properties

Reactions of H₂L [H₂L = N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine] and Ln(NO₃)₃ · 6H₂O give rise to two different mononuclear 4f complexes, namely, {[(H₂L)La(NO₃)₃(MeOH)] · H₂O}_n (1) and [(H₂L)Nd(NO₃)₃] (2). Further additions of Cu(Ac)₂ · H₂O to the mononuclear 4f complexes yield expected heterodinuclear Cu-4f complexes [LCu(Me₂CO)Ln(NO₃)₃] (3, Ln = Nd; 4, Ln = Eu; 5, Ln = Dy). Complex 1 is a unique 1D polymeric chain structure, and 2 is one of the few structurally characterized discrete hexadentate salen-type mononuclear 4f complexes. Complexes 3-5 are similar to their analogues. However, they are prepared by a reversed synthetic route in contrast to their isomorphic complexes. Electrochemical behavior of heterodinuclear Cu-4f complexes 3-5 has been examined by cyclic voltammetry in acetonitrile. The redox potential of heterodinuclear Cu-4f complexes 3-5 shows significant anodic shift comparing to that of mononuclear copper complex (LCu). A tendency of anodic shift was observed in a sequence of 3 < 4 < 5. This results from the modulating effect of coordination geometry around Cu(II) ion on redox potential.     

Dinuclear gold(III) pyrazolato complexes - Synthesis, structural characterization and transformation to their trinuclear gold(I) and gold(I/III) analogues

The reaction of AuCl₃py with Na(pz∗) (pz∗ = pyrazolato, or substituted pyrazolato anion) yields stable dinuclear [cis-Au^IIICl₂(μ-pz∗)]₂ complexes. In the presence of a base, the latter undergo reduction with concomitant transformation of the dinuclear -structure to trinuclear Au^I, Au^III (containing trans Au^IIICl₂-centres) and species.     

Synthesis, structure, solution chemistry and the electronic effect of para substituents on the vanadium center in a family of mixed-ligand [VO(ONO)(ON)] complexes

Four tridentate dibasic ONO donor hydrazone ligands derived from the condensation of benzoylhydrazine with either 2-hydroxyacetophenone or its para substituted derivatives (H₂L^1-4, general abbreviation H₂L) have been used as primary ligands and 8-hydroxyquinoline (Hhq, a bidentate monobasic ON donor species) has been used as auxiliary ligand. The reaction of [V^IVO(acac)₂] with H₂L in methanol followed by the addition of Hhq in equimolar ratio under aerobic condition afforded the mixed-ligand oxovanadium(V) complexes of the type [V^VO(L)(hq)] (1-4) in excellent yield. The X-ray structure of the compound [V^VO(L⁴)(hq)] (4) indicates that the H₂L⁴ ligand is bonded with vanadium meridionally in a tridentate dinegative fashion through its deprotonated phenolic-O, deprotonated enolic-O and imine-N atoms. The V-O bond length order is: oxo < phenolato < enolato. ¹H NMR spectra of 4 in CDCl₃ solution indicates that it’s solid-state structure is retained in solution. Complexes are diamagnetic and exhibit only ligand to metal charge transfer (LMCT) transition band near 530 nm in CH₂Cl₂ solution in addition to intra-ligand π → π^∗ transition band near 335 nm and they display quasi-reversible one electron reduction peak near − 0.10 V versus SCE in CH₂Cl₂ solution. λ_max (for LMCT transition) and the reduction peak potential values of the complexes are found to be linearly related with the Hammett (σ) constants of the substituents in the aryloxy ring of the hydrazone ligands. λ_max and values show large dependence dλ_max/dσ = 32.54 nm and V, respectively, on the Hammett constant.     

Molecular and electronic structures of new iron complexes containing N,S-coordinated o-iminothionebenzosemiquinonate(1-) π radical ligands: An experimental and density functional theoretical study

Two new o-aminothiophenol type ligands have been synthesized, namely 1,3-propanediamine-N,N′-bis(benzenethiol), H₄(¹L), and 1,2-bis(2-mercapto-3,5-di-tert-butylaniline)ethane, H₄(²L). The reactions of these ligands with FeBr₂ in dry acetonitrile in the presence and absence of air (and other oxidants such as iodine) afforded seven new complexes which were characterized by single-crystal X-ray crystallography and Mössbauer spectroscopy (as well as EPR- and UV-Vis spectroscopies). Their magnetochemistry has been studied and their electronic structures have been established and verified by broken symmetry (BS) density functional theoretical (DFT) calculations using the B3LYP functional. The ligands are redox-active and the o-iminothiophenolate(2-)-o-iminothiobenzosemiquinonate(1-) oxidation levels are chemically readily accessible. The complexes characterized comprise the dimers [Fe^III(¹L)]₂ (S_T = 0) (1); [Fe^III(²L)]₂ (S_T = 0) (2), and the mononuclear, five coordinate species: [Fe^III(¹L)I] (S_T = ¹/₂) (3); [Fe^III(²L)I] (S_T = ¹/₂) (4); [Fe^II(¹L){P(CH₃)₃}] (S_T = 0) (5); [Fe^II(²L){P(C₆H₅)₃}] (S_T = 0) (6), and [Fe^III(²)(^tpy)] (S_T = 1) (7). (^tBupy) represents 4-tert-butylpyridine and (²)³⁻ is the π radical trianion of the one-electron reduced (²L_gma)²⁻ which in turn is the oxidized form of (²L)⁴⁻ (−4H⁺, −2e).     

Synthesis of organophosphorus compounds containing different Y,C,Y-chelating ligands. Crystal structure of P ← N intramolecularly coordinated diselenoxophosphorane

The reactions of L^1-3Li salts containing different Y,C,Y-chelating ligands L¹ = 2,6-(t-BuOCH₂)₂C₆, L² = 2,6-(MesOCH₂)₂C₆ and L³ = 2,6-(Me₂NCH₂)₂C₆ with PCl₃ is reported. While the presence of ligands L^2,3 afforded the synthesis of dichlorophosphines L²PCl₂ (2) and L³PCl₂ (3), the use of ligand L¹ resulted to the isolation of O → P coordinated 1-chloro-7-(t-butoxymethyl)-3H-2,1-benzoxaphosphole (1) as the result of the cyclization type reaction of dichlorophosphines L¹PCl₂. The hydrolysis of compounds 1-3 as well as the preparation of phosphanes L²PH₂ (7), L³PH₂ (8), L²PH(SnMe₃) (9) and L³PH(SnMe₃) (10) is also discussed. The presence of N → P coordination enabled the isolation of N → P coordinated diselenoxophosphorane L³PSe₂ (11). Compounds 1-11 were characterized by the help of multinuclear NMR spectroscopy, ESI mass spectrometry and the structure of compound 11 was established by X-ray diffraction analysis.     

Two cyano-bridged heterotrinuclear complexes built from [(Tp)Fe(CN)3] (Tp = hydrotris(pyrazolyl)borate): synthesis, crystal structures and magnetic properties

Using an anionic precursor [(Tp)Fe^III(CN)₃]⁻ (1) as a building block, two cyano-bridged centrosymmetric heterotrinuclear complexes, (2) and (3) (en = ethylenediamine), have been synthesized and structurally characterized. In each complex, [TpFe(CN)₃]⁻ acts as a monodentate ligand toward a central [Mn(C₂H₅OH)₄]²⁺ or [Ni(en)₂]²⁺ core through one of its three cyanide groups, the other two cyanides remaining terminal. The intramolecular Fe-Mn and Fe-Ni distances are 5.2354(4) and 5.0669(11) Å, respectively. The magnetic properties of complexes 2 and 3 have been investigated in the temperature range of 2.0-300 K. A weak antiferromagnetic interaction between the Mn(II) and Fe(III) ions has been found in complex 2. The magnetic data of 2 can be fitted with the isotropic Hamiltonian: where J and J′ are the intramolecular exchange coupling parameters between adjacent and peripheral spin carriers, respectively. This leads to values of J = −1.37 cm⁻¹ and g = 2.05. The same fitting method is applied to complex 3 to give values of J = 1.2 cm⁻¹ and g = 2.25, showing that there is a ferromagnetic interaction between the Fe(III) and Ni(II) ions.     

Manganese(II) complexes of di-2-pyridinylmethylene-1,2-diimine di-Schiff base ligands: Structures and reactivity

Manganese(II) complexes [Mn(L)X₂] were prepared and characterized, where L is a neutral di-Schiff base ligand incorporating pyridylimine donor arms, including (1R,2R)-N,N′-bis(2-pyridylmethylidene)-1,2-diphenylethylenediimine (L¹), (1R,2R)-N,N′-bis(6-methyl-2-pyridylmethylidene)-1,2-cyclohexyldiimine (L²), or (1R,2R)-, (1S,2S)- or racemic N,N′-bis(2-pyridylmethylidene)-1,2-cyclohexyldiimine (L³), and X⁻ =  or Cl⁻. Product complexes were structurally characterized, specifically including [Mn(R,R-L¹)(NCCH₃)₃](ClO₄)₂, [Mn(R,R-L²)(OH₂)₂](ClO₄)₂ and racemic [Mn(L³)Cl₂]. The first of these complexes features a heptacoordinate ligand field in a distorted pentagonal bipyramid, and the latter two are hexacoordinate, but retain equatorially monovacant pentagonal bipyramidal structures. Complexes [Mn(L³)X₂] (X⁻ = Cl⁻, ) were reacted with the primary phosphine FcCH₂PH₂ (Fc = -C₅H₄FeC₅H₅), H₂O and ethyldiazoacetate (EDA). The first two substrates prompted reactivity at a single ligand imine bond, resulting in hydrophosphination and hydrolysis, respectively. Complexes of the derivative ligands were also structurally characterized. Evidence for EDA activation was obtained by electrospray ionization mass spectrometry, but catalytic carbene transfer was not obtained.     

Two-dimensional oxides constructed from octamolybdate clusters and M/tetrapyridylpyrazine subunits (M = Co, Ni: n = 2; M = Cu: n = 1)

The hydrothermal reactions of MoO₃, tetra-2-pyridylpyrazine (tpyprz) and M(CH₃CO₂)₂ · 2H₂O (M = Co, Ni) yielded the two-dimensional oxides [M₂(tpyprz)(H₂O)₂Mo₈O₂₆] · xH₂O [M = Co, x = 1.8 (1); M = Ni, x = 0.6 (2)]. However, the reaction of (NH₄)₆Mo₇O₂₄ · 4H₂O, tpyprz and Cu(CH₃CO₂)₂ · H₂O produced [{Cu₂(tpyprz)}₂Mo₈O₂₆] · 2H₂O (3 · 2H₂O). The isomorphous structures of 1 and 2 are constructed from clusters linked through {M₂(tpyprz)(H₂O)₂}⁴⁺ subunits into two-dimensional networks. While the structure of 3 is also two-dimensional, the molybdate building block is present as the δ-isomer and the secondary-metal/ligand component consists of a one-dimensional chain. The structure of 3 is compared to that of the previously reported three-dimensional material [{Cu₂(tpyprz)}₂Mo₈O₂₆] · 7H₂O which contains clusters and structurally distinct chains.     

Synthesis of bimetallic fulvalene and bis(cyclopentadienyl)methane derivatives of niobium and tantalum tetracarbonyl

Ring coupled bimetallic derivatives (μ-η^5:5-C₅H₄C₅H₄)[Nb(CO)₄]₂ and [μ-CH₂(η⁵-C₅H₄)₂][M(CO)₄]₂, where M = Nb and Ta have been prepared. The molecular structures of the latter two compounds have been determined: , triclinic, , a = 8.028(2) Å, b = 11.414(1) Å, c = 12.711(2) Å, α = 75.020(8)°, β = 80.34(2)°, γ = 79.46(2)°, V = 1097.3(4) ų, Z = 2, R(F) = 2.79%; [μ-CH₂(η⁵-C₅H₄)₂][Ta(CO)₄]₂, triclinic, , a = 7.815(3) Å, b = 10.275(4) Å, c = 13.135(4) Å, α = 104.25(3)°, β = 100.26(4)°, γ = 96.86(3)°, V = 991.2(6) ų, Z = 2, R(F) = 3.00%.     

Solution and solid-state complexes of the potentially tetradentate pyridyl-thiazole ligand 6,6′-bis(4-methylthiazol-2-yl)-2,2′-bipyridine with Co, Ni, Cu, Cd, Hg, Cu and Ag

Reaction of the potentially tetradentate N-donor ligand 6,6′-bis(4-methylthiazol-2-yl)-2,2′-bipyridine (L¹) with the transition metal dications Co^II, Ni^II, Cu^II, Cd^II and Hg^II results in the formation of mononuclear [M(L¹)]²⁺ complexes, in which a planar ligand coordinates to the metals via all four N-donors. In contrast, reaction of L¹ with Cu^I and Ag^I monocations, affords dinuclear double stranded helicate species [M₂(L¹)₂]²⁺ (where M = Cu^I or Ag^I), in which partitioning of the ligand into two bis-bidentate pyridyl-thiazole chelating units allows each ligand to bridge both metal centres. X-Ray crystallography, electrospray mass spectroscopy and NMR spectroscopy reveal that the complexes [M_n(L¹)_m]^z+ (where n = 1, m = 1 and z = 2, when M = Co^II, Ni^II, Cu^II, Cd^II and Hg^II; n = 2, m = 2 and z = 2, when M = Cu^I), retain their solid-state structures in solution. Conversely, whilst ¹H NMR studies suggest that combination of equimolar amounts of Ag(X)(where ) and L¹ (in either nitromethane or acetonitrile) results in the formation of a helicate in solution, in the solid-state, an anion-templating effect gives rise to either mononuclear or dinuclear helicate structures [Ag_n(L¹)_n][X]_n (where n = 2 when X = OTf⁻; n = 1 when ).     

Synthesis, crystal structures and characterization of three novel complexes with N-[2-(2-hydroxybenzylideneamino)ethyl]-4-methyl-benzene-sulfonamide as ligand

Reaction of the N-tosyl-ethylenediamine and salicylaldehyde forms a new sulfonamide Schiff base N-[2-(2-hydroxybenzylideneamino)ethyl]-4-methyl-benzene-sulfonamide (H₂L). Three novel complexes constructed from H₂L, namely, [M(HL)₂] · xH₂O (M = Cu, x = 0 for 1, M = Ni, x = 0 for 2 and M = Zn, x = 1 for 3) have been prepared and characterized via X-ray single-crystal diffraction, elemental analysis, X-ray powder diffraction (XRPD), FT-IR, UV-Vis, TGA and photoluminescence measurements. Complex hydrogen bonds, C-H···π and π-π stacking interactions lead 1-3 to present 1-D, 2-D and 3-D supramolecular architectures, respectively.