Single stranded helical supramolecular architecture with a left handed helical water chain in ternary copper(II) tryptophan/diamine complexes

The ternary copper(II) complexes [Cu(l-trp)(bpy)](ClO₄) (1) and [Cu(l-trp)(phen)] (ClO₄) · 3H₂O (2) (where l-trp = l-tryptophan, bpy = bipridyl, phen = phenanthroline) have been synthesized. The single crystal X-ray structures for these complexes revealed that the monocationic Cu^II-units are interlinked through Cu–OCO–Cu connectivity and exist as helical coordination polymers. The two different helical strands composed with Cu1 and Cu2 independently, possess a similar pitch distance of 7.713 Å in complex 1. For complex 2, existing in the hydrated form, the Cu(II) polymeric strand and the hydrated water molecules have gained a supramolecular helical architecture with a similar pitch distance of 8.133 Å. The two helical strands in complex 1 are associated with right handed (PP) supramolecular chirality, while the helical water chain and the Cu^II-strand in 2 are self assembled into left handed (MM) helicity in the solid state. The solid state CD recorded for 1 and the dehydrated form of 2 exhibit a positive optical sign at their respective d–d band [λ_max = 667 nm, 1; λ_max = 630 nm, 2], the solution state CD for both these complexes are found to be inverted into a negative optical sign, which could be attributed to inversion of their associated supramolecular helicity. The TGA curve illustrates two distinct weight losses at 60 °C and 87 °C, equivalent to one and two water molecules, respectively. The PXRD pattern for the hydrated and dehydrated forms of 2 indicated a change, on comparison with the simulated diffractograph. The fluorescence properties of both these complexes, possessing tryptophan and bipy/phen, were investigated.     

Novel copper complexes based on the thiocyanate bridge - Synthesis, X-ray studies and magnetic properties

Three novel compounds {[Cu(bpzm)(SCN)][Cu(bpzm)(MeOH)][Cu(SCN)₄]}_n (1a), {[Cu₂(bpzm)₂(μ-SCN)(SCN)₃]}_n (1b) and [Cu₂(μ-SCN)₂(SCN)₂(dpa)₂] (2) have been obtained in one-step self-assembly reaction of copper dichloride, a suitable N-N ligand (bis(pyrazol-1-yl)methane and 2,2′-dipyridylamine) and ammonium thiocyanate. For the reaction involving bis(pyrazol-1-yl)methane, an unprecedented in situ reduction of some Cu(II) ions to Cu(I) has been observed. The compound {[Cu(bpzm)(SCN)][Cu(bpzm)(MeOH)][Cu(SCN)₄]}_n (1a) belongs to a relatively scarce group of mixed-valence Cu^II/Cu^I coordination polymers with interesting polymeric architecture. It creates infinite two-dimensional structure consisting of layers extending along crystallographic plane (0 0 1), in which the cations [Cu^II(bpzm)(SCN)]⁺ and [Cu^II(bpzm)(MeOH)]²⁺ are connected by ions [Cu^I(SCN)₄]³⁻ through single end-to-end thiocyanato bridges. Structure 1b consists two crystallographically independent chains. The chain A has a zig-zag form and extends along the crystallographic direction [0 0 1], whereas the second chain is linear and runs along the crystallographic direction [0 1 0]. The structure 2 consists of dinuclear [Cu₂(dpa)₂(μ-SCN)₂(SCN)₂] units. Variable-temperature magnetic susceptibility measurements show very weak antiferromagnetic interactions between the paramagnetic centres Cu(II) centers inside the crystal lattices of three novel compounds.     

Nickel(II) and copper(II) complexes of unsymmetrical tetradentate reduced Schiff base ligands

Two new reduced Schiff base ligands, [HL¹ = 4-{2-[(pyridin-2-ylmethyl)-amino]-ethylimino}-pentan-2-one and HL² = 4-[2-(1-pyridin-2-yl-ethylamino)-ethylimino]-pentan-2-one] have been prepared by reduction of the corresponding tetradentate unsymmetrical Schiff bases derived from 1:1: 1 condensation of 1,2-ethanediamine, acetylacetone and pyridine-2-carboxaldehyde/2-acetyl pyridine. Four complexes, [Ni(L¹)]ClO₄ (1), [Cu(L¹)]ClO₄ (2), [Ni(L²)]ClO₄ (3), and [Cu(L²)]ClO₄ (4) with these two reduced Schiff base ligands have been synthesized and structurally characterized by X-ray crystallography. The mono-negative ligands L¹ and L² are chelated in all four complexes through the four donor atoms to form square planar nickel(II) and copper(II) complexes. Structures of 3 and 4 reveal that enantiomeric pairs are crystallized together with opposite chirality in the nitrogen and carbon atoms. The two Cu^II complexes (2 and 4) exhibit both irreversible reductive (Cu^II/Cu^I; E_pc, −1.00 and −1.04 V) and oxidative (Cu^II/Cu^III; E_pa, +1.22 and +1.17 V, respectively) responses in cyclic voltammetry. The electrochemically generated Cu^I species for both the complexes are unstable and undergo disproportionation.     

Assembly of cyano-bridged Cu(II)/Cu(II) and Cu(I)/Cu(II) compounds obtained by controlled ration of cyanide

One reaction system of Cu²⁺, dipn, and CN⁻ with two different molar ratio sets of 1:1:5, and 2:1:8 produced two compounds 1 [Cu^II(dipn)][Cu^II(CN)₄], and 2, respectively (dipn = dipropylenetriamine). Their structures were determined by X-ray crystallography. Compound 2 is built from Cu(I) and Cu(II) centers, which are bridged by cyanide groups and metal-metal bonds. The magnetic properties of 1 and 2 were investigated in 2-300 K. Compound 1 exhibits an antiferromagnetic exchange interaction between copper(II) ions mediated by cyano-bridges.     

Copper(II) complexes of tridentate selenobisphenolate ligand in mixed ligand environments: Synthesis, crystal structure, EPR and electrochemical studies

A series of square-pyramidal copper(II) complexes, [Cu(L^Se)(N^∧N)] (H₂L^Se = seleno-bisphenolate; N^∧N = bipyridyl, phenanthroline or N,N-dimethylethylenediamine) have been synthesized and characterized by elemental analyses, magnetic measurements, IR, EPR, and electronic spectral studies. Single crystal X-ray structures of [Cu(L^Se)(bpy)]·H₂O (2), [Cu(L^Se)(phen)]·CH₂Cl₂ (3) and [Cu(L^Se)(N,N-Me₂en)] (4) showed that all the complexes have approximately square-pyramidal geometry. In complexes 2 and 3, the square plane is occupied by O(1), O(2), N(1) and N(2) and the apical position by Se atom of L^{Se 2−} ligand. The asymmetric unit of complex 4 contains two crystallographically independent discrete molecules A and B with CuN₂OSe chromophore comprising the square plane and the axial position being occupied by another phenolate oxygen atom. Complexes 2, 3 and 4 are found to be paramagnetic and EPR parameters extracted are: g_∥ = 2.232, g_⊥ = 2.069; 〈g_eff〉 = 1.95; and g_∥ = 2.232, g_⊥ = 2.083 for complexes 2, 3 and 4, respectively. Both the complexes 2 and 4 show three reduction processes: (a) a quasi-reversible reduction of Cu^II to Cu^I, (b) an irreversible reduction of Cu^I to Cu⁰ with the release of free ligand, and (c) a reduction process occurs at this coordinated ligand. They also show a well-defined quasi-reversible oxidation of Cu^II to Cu^III and an irreversible oxidation peak at ∼1.30 and 1.40 V vs. Ag/AgCl for 4 and 2, respectively, with no cathodic counterpart, and were attributed to the oxidation of the metal coordinated ligand.     

Synthesis,crystal structures and magnetic properties of five new metal(II) compounds constructed with isomers of aminobenzonitrile and dicyanamide ligands

Five new compounds formulated as [Ni^II(dca)₂(para-ABN)₂(H₂O)₂] (1), [Cu^II(dca)₂(para-ABN)₂(H₂O)₂] (2), [Cu^II(dca)₂(para-ABN)₂]_n, (3), [Cu^II(dca)₂(ortho-ABN)₂]_n, (4) and [Cd^II(dca)₂(meta-ABN)₂]_n (5), where dca = dicyanamide and ABN = aminobenzonitrile, have been synthesized and characterized by single crystal X-ray diffraction studies and low temperature (300–2 K) magnetic measurements. The structural analyses revealed that 1 and 2 are isomorphous where dca and para-ABN both act as monodentate ligands. 3 consists of infinite double stranded chains of Cu(II) ions connected through the para-ABN bridges whereas 4 and 5 consist of infinite double stranded chains of Cu(II) and Cd(II) respectively, connected through μ_1,5-dca bridges. The compounds extend their geometries to three-dimensional for 1–3 and 5 and two-dimensional for 4 through hydrogen bonding interactions. All the metal ions Ni²⁺, Cu²⁺ and Cd²⁺ are located on inversion centres and have distorted octahedral coordination geometries. The variable temperature magnetic susceptibility measurements show that the global feature of the χ_MT versus T curves for 3 and 4 is characteristic of very weak antiferromagnetic interactions and between 300 and 2 K the best fit parameters were determined as J = −2.35 and −5.1 cm⁻¹, respectively.     

Complexes derived from the general copper(II)/maleamic acid/N,N′,N′′-chelate reaction systems: Synthetic,reactivity, structural and spectroscopic studies

The synthetic investigation of the Cu^II/maleamate(−1) ion (HL⁻)/N,N′,N′′-chelate general reaction system has allowed access to compounds [Cu₂(HL)₂(bppy)₂](ClO₄)₂·H₂O (1·H₂O), [Cu(HL)(bppy)(ClO₄)] (2) and [Cu(HL)(terpy)(H₂O)](ClO₄) (4) (bppy = 2,6-bis(pyrazol-1-yl)pyridine, terpy = 2,2′;6′,2′′-terpyridine). In the absence of externally added hydroxides, compound [Cu₂(L′)₂(bppy)₂](ClO₄)₂ (3) was obtained from MeOH solutions; L′⁻ is the monomethyl maleate(−1) ligand which is formed in situ via the Cu^II-assisted HL⁻ → L′⁻ transformation. In the case of tptz-containing (tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) reaction systems, the Cu^II-assisted hydrolysis of tptz to pyridine-2-carboxamide (L1) afforded complex [Cu(L1)₂(NO₃)₂] (5). The crystal structures of 1–5 are stabilized by intermolecular hydrogen bonding and π–π stacking interactions. Characteristic IR bands of the complexes are discussed in terms of the known structures and the coordination modes of the ligands.     

Temperature dependence on recrystallisation of the magnesium phthalocyanine (MgPc) in triethylamine

Three complexes of magnesium phthalocyaninato(2−) derivatives in the crystalline form, MgPc(H₂O)·(C₂H₅)₃N – (I), MgPc(H₂O)₂·2(C₂H₅)₃N – (II) and MgPc(H₂O)₂ – (III), depending on the thermal recrystallisation conditions were obtained and structurally characterised. In complex I, the Mg center exhibits square-pyramidal (4 + 1) coordination environment, whereas in II and III the Mg center of MgPc the biaxial (4 + 2) coordination. Owing to the interaction of the positively charged Mg center with oppositely charged oxygen atom of water molecule in an axial position in I, the Mg atom is significantly displaced (0.451(2) Å) from the plane defined by four isoindole N atoms and leads to distortion of the planar Pc(2−) macrocycle to the saucer-shape form. In II and III due to the biaxial (4 + 2) coordination of the Mg center of MgPc, the Mg atom lies on a N₄-isoindole plane. The triethylamine solvent molecules in I and II interact with mono or bis(aqua)magnesium phthalocyanine via   O–H?$?$N hydrogen bonds. The axial Mg–O bond in I is significantly shorter than that in the II and III complexes. The strength of the Mg–O bond in these complexes is correlated with their thermal stability. From among the complexes only complex I exhibits an intense near-IR absorption band in the solid-state. The spectra of I, II and III in solution are very similar.     

Mixed ligand complexes of AEE hexafluoroacetylacetonates with diglyme: Synthesis,crystal structure and thermal behavior

The novel mixed ligand complexes [Ca(hfa)₂(diglyme)(H₂O)] (I), [Sr(hfa)₂(diglyme)(H₂O)] (II) and [Ba(hfa)₂(diglyme)₂] (III) (Hhfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, diglyme = 2,5,8-trioxanonane) were synthesized by the reactions of the alkaline earth element (AEE) carbonates in n-hexane with a mixture of Hhfa and diglyme, and they were characterized by elemental analysis, ¹H and ¹³C NMR, and FTIR spectroscopy. The crystal structures of I–III, consisting of mononuclear isolated molecules, have been determined. The thermal behavior and composition of the vapor phase have been studied for I–III by thermal analysis at low pressure and mass spectrometry using a Knudsen cell. The stability of the mixed ligand complexes [M(hfa)₂(diglyme)_n] to the removal of diglyme molecules under heating decreases in the row I > II ≈ III, and only I evaporates as the mixed ligand complex after water removal.     

Hetero-metallic frameworks of [Pd(CN)4] and Cu(II) with triamines: A rare example of a tetracyanometallate bridged 2D coordination polymer

Four cyano bridged Cu(II)–Pd(II) heterometallic complexes, [Cu(dpt)Pd(CN)₄]_n (1), {[Cu₂(medpt)₂Pd(CN)₄](ClO₄)₂ · 3H₂O}_n (2), {[Cu₂(dien)₂Pd(CN)₄](ClO₄)₂ · 2CH₃OH}_n (3) and {[Cu₂(iPrdien)₂Pd(CN)₄](ClO₄)₂ · 2H₂O}_n (4) [dpt = 3,3′-iminobispropylamine; medpt = 3,3′-diamino-N-methyldipropylamine; dien = diethylenetriamine and iprdien = N′-isopropyldiethylenetriamine] have been synthesized and characterized by single crystal X-ray diffraction analysis, magnetic measurement and thermal study. Complexes 1, 2 and 3 are 1D coordination polymers, while 4 presents a 2D network. In 1, the cis-directed cyanide ligands of [Pd(CN)₄]²⁻ anions link two Cu(dpt) units to form a neutral coordination polymer, whereas in 2, 3 and 4, all the cyanide groups of [Pd(CN)₄]²⁻ take part in bonding with four adjacent Cu(II) ions, resulting in cationic coordination polymers counterbalanced by perchlorate anions. The structures are compared with those of analogous [Ni(CN)₄]²⁻ derivatives. The magnetic behavior shows antiferromagnetic interactions in all the complexes.     

3D-supramolecular copper(I) cyanide coordination polymers through hydrogen bonding

The reactions of K₃[Cu(CN)₄], 3-acetylpyridine (3-Acpy) or 4-acetylpyridine (4-Acpy) in the presence of Me₃SnCl in H₂O/acetonitrile media at room temperature afford the 3D-supramolecular coordination polymers (SCPs)_∞³[Cu₂CN(μ-CN)·(3-Acpy)₂] 1 and _∞³[Cu₂CN(μ-CN)·(4-Acpy)₂] 2. The structures of 1 and 2 consist of Cu₂CN building blocks which are connected by CN groups, forming 1D-zig-zag chains. Each chain is bonded to another chain by hydrogen bonding into a 2D-layer, which is further stacked in an interwoven mode by π–π stacking interactions and hydrogen bonds in 1 and 2, as well as Cu···Cu interactions in 1, to create supramolecular 3D-network structures. The high dimensional topologies of 1 and 2 result mainly from extensive hydrogen bonding and π–π stacking. The long wavelength absorption band at 400–420 nm in the electronic spectra of 1 and 2 is assigned to a CT from copper(I) to the Acpy ligand. Compound 2 exhibits strong luminescence at 485 and 527 nm, corresponding to MLCT and metal-centered transitions, respectively.     

Structure,stacking interactions and magnetism of compounds with oxalate-bridged dinuclear CuCu and CuNb units

Two novel compounds of the formulae [{Cu(phen)₂}₂(μ-C₂O₄)][Cu(phen)₂(μ-C₂O₄)NbO(C₂O₄)₂]₂ · 8H₂O (1) and [{Cu(bpy)₂}₂(μ-C₂O₄)][Cu(bpy)₂(μ-C₂O₄)NbO(C₂O₄)₂]₂ · 0.5bpy · 7H₂O (2) (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) have been prepared and characterized by single crystal X-ray diffraction, IR spectroscopy and magnetic susceptibility measurements. The molecular structure of both 1 and 2 consists of a discrete Cu^IICu^II oxalate-bridged dinuclear [{Cu(L)₂}₂(μ-C₂O₄)]²⁺ cation (A unit) and two Cu^IINb^V oxalate-bridged dinuclear [Cu(L)₂(μ-C₂O₄)NbO(C₂O₄)₂]⁻ anions (B units) (L = phen, bpy). In 1 a crystallographic inversion centre is located in the middle of the oxalate bridge of the A unit, whereas in 2 an analogous inversion centre is missing. In the A units the copper(II) atoms adopt a tetragonally elongated octahedral coordination with the equatorial planes being perpendicular to the mean planes of the oxalate bridge and parallel to each other. In both structures, similar one-dimensional motifs are generated through the ligand stacking interactions, with a difference that one free bipyridine molecule, present in 2, intercalates into one of the motifs. It is shown that the phenanthroline ligand, due to its ability of stacking through the central aromatic ring, causes longer intermolecular Cu?Cu distances than the bipyridine ligand. The magnetic susceptibility measurements (1.8–290 K) show the ferromagnetic exchange interaction between the copper(II) atoms in the A units of both compounds, with J = +5.9 cm⁻¹ and +7.9 cm⁻¹ for 1 and 2, respectively (J – the exchange parameter in the isotropic spin Hamiltonian H_INT = −JS₁ · S₂).     

New 3d–4f supramolecular systems constructed by [Fe(bipy)(CN)4] and partially blocked lanthanide cations

The reaction of acetonitrile (1–5) and mixed acetonitrile/water 1:1 (6–9) solutions containing the cyanide-bearing [Fe(bipy)(CN)₄]⁻ building block (bipy = 2,2′-bipyridine) and the partially blocked [Ln(bpym)]³⁺ cation (Ln = lanthanide trivalent cation and bpym = 2,2′-bipyrimidine) has afforded two new families of 3d–4f supramolecular assemblies of formula [Ln(bpym)(NO₃)₂(H₂O)₃][Fe(bipy)(CN)₄] · H₂O · CH₃CN [Ln = Sm (1), Gd (2), Tb (3), Dy (4) and Ho (5)] and [Ln(bpym)(NO₃)₂(H₂O)₄][Fe(bipy)(CN)₄] [Ln = Pr (6), Nd (7), Sm (8), Gd (9)]. They crystallize in the P2₁/c (1–5) and P2/c (6–9) space groups and their structures are made up of [Fe(bipy)(CN)₄]⁻ anions (1–9) and [Ln(bpym)(NO₃)₂(H₂O)_n]⁺ cations [n = 3 (1–5) and 4 (6–9)] with uncoordinated water and acetonitrile molecules (1–5) which are interlinked through an extensive network of hydrogen bonds and π–π stacking into three-dimensional motifs. Both families have in common the occurrence of the low-spin iron(III) unit [Fe(bipy)(CN)₄]⁻ where two bipy–nitrogen and four cyanide–carbon atoms build a somewhat distorted octahedral surrounding around the iron atom [Fe–N = 1.980(3)–1.988(3) Å (1–5) and 1.988(2)–1.992(2) Å (6–9); Fe–C = 1.904(5)–1.952(4) Å (1–5) and 1.911(2)–1.948(3) Å (6–9)]. The main structural difference between both families concerns the environment of the lanthanide atom which is nine- (1–5)/10-coordinated (6–9) with a chelating bpym, two bidentate nitrate and three (1–5)/four (6–9) water molecules building distorted monocapped (1–5)/bicapped (6–9) square antiprisms. This different lanthanide environment is at the origin of the different hydrogen bonding pattern of the two families of compounds.     

Structural and magnetic properties of metal complexes with pyridine-2,6-dicarboxylate and 5-(4-bromophenyl)-2,4′-bipyridine

A series of complexes has been synthesized based on pyridine-2,6-dicarboxylate (L1) as the bridging ligand and 5-(4-bromophenyl)-2,4′-bipyridine (L2) as the pendant with different metal ions such as Ni^II, Co^II, and Cu^II, under hydrothermal conditions. In nickel and cobalt complexes [M(L1)(L2)₂ · H₂O]_n (M = Ni²⁺ or Co²⁺), the metal ions are bridged by L1 to form 1D coordination zigzag polymeric chains with L2 pendants possessing hexa-coordinated distorted octahedral geometries. While the copper ions are penta-coordinated by L1 and L2 with distorted square pyramidal geometries forming the tetranuclear cluster with the formula [Cu₄(L1)₄(L2)₄] · 2H₂O. It has been found that both the structure and magnetic property of these complexes are metal ions dependent. Intramolecular antiferromagnetic interactions were observed in the nickel and cobalt 1D coordination polymers, while ferromagnetic coupling was found in the tetranuclear copper cluster. Density functional theory calculations suggested that the O–C–O bridges of L1 in a basal–apical mode are responsible for intracluster intermetallic ferromagnetic exchange for the tetranuclear copper cluster.     

Magnetic coupling in EE and EO azido-bridged binuclear copper complexes: Synthesis,structure and magnetic studies

Four azide bridged dinuclear copper(II) complexes, [Cu₂(L^X)₂(N₃)₂](ClO₄)₂, with L^X = substituted N,N-bis[(3,5-dimethylpyrazole-1-yl)-methyl]benzylamine, [X = H (1), OMe (2), Me (3) and Cl (4)] have been synthesized, out of which complexes 1 and 2 have been characterized structurally. In Complex 1 the two bridging azide ligands have connected the two metal centers in an end-on (EO) fashion with aSP (asymmetric Square Pyramidal) geometry and showed an weak antiferromagnetic interaction (J = −3.34 cm⁻¹). On the contrary, in complex 2, the two metal centers have been connected in end-to-end (EE) fashion exhibiting moderately strong ferromagnetic interaction (J = +19.7 cm⁻¹). Cyclic voltammetric studies performed on all the four complexes show a reasonably good correlations when E_1/2 for Cu^IICu^II → Cu^IICu^III and Cu^IICu^III → Cu^IIICu^III oxidations are plotted against σ (substituent constants) with ρ = −0.182 (R² = 0.92) and −0.684 (R² = 0.99) respectively.     

Dinuclear copper(II) complexes of a novel 3-(aminomethyl)naphthoquinone Mannich base: Synthesis,structural, magnetic and electrochemical studies

A novel versatile tridentate 3-(aminomethyl)naphthoquinone proligand, 3-[N-(2-pyridylmethyl)aminobenzyl]-2-hydroxy-1,4-naphthoquinone (HL), was obtained from the Mannich reaction of 2-hydroxy-1,4-naphthoquinone (Lawsone) with 2-aminomethylpyridine (amp) and benzaldehyde. The reactions of HL with CuCl₂·2H₂O yielded two novel dinuclear copper(II) complexes, [Cu(L)(H₂O)(μ-Cl)Cu(L)Cl] (1b), [CuCl(L)(μ-Cl)Cu(amp)Cl] (2) and a polymeric compound, [Cu(L)Cl)]_n (1a), whose relative yields were sensitive to temperature, reagents concentration and presence of base. The crystalline structures of 1b and 2 were determined by X-ray diffraction studies. The two copper atoms in complex 1b are connected by a single chloro bridge with a Cu?Cu separation of 4.1342(8) Å and Cu(1)–Cl(1)–Cu(2) angle of 109.31(4)°. In complex 2 the two copper atoms are held together by a chloro and a naphthalen-2-olate bridges [Cu(1)–Cl(2)–Cu(2) and Cu(1)–O(1)–Cu(2) angles being 83.31(3) and 109.70(9)°, respectively, and the Cu?Cu separation, 3.3476(9) Å]. As expected, variable-temperature magnetic susceptibility measurements of complex 1b showed weak antiferromagnetic intramolecular coupling between the copper(II) centers, with J = −5.7 cm⁻¹, and evidenced for complex 2 strong antiferromagnetic coupling, with J ∼ −120 cm⁻¹. Furthermore, the magnetic behaviour of compound 1a suggested an infinite 1D coordination polymeric structure in which the copper(II) centers are connected by Cl–Cu–Cl bridges. Solution data (UV–Vis spectroscopy and cyclic voltammetry) indicated structural changes of 2 and 1a in CH₃CN, and evidenced conversion of polymer 1a into dimer 1b.     

A “sodium trap” based on benzo-15-crown-5 with an exocyclic N-(thiophosphoryl)thiourea moiety

For N-(thio)phosphorylthioureas of the common formula RC(S)NHP(X)(OiPr)₂HL^I (R = N-(4′-aminobenzo-15-crown-5), X = S), HL^II (R = N-(4′-aminobenzo-15-crown-5), X = O), HL^III (R = PhNH, X = S), HL^IV (R = PhNH, X = O), and (N,N′-bis-[C(S)NHP(S)(OiPr)₂]₂-1,10-diaza-18-crown-6) H₂L^V, salts LiL^I,III,IV, NaL^I–IV, KL^I–IVM₂L^V (M = Li⁺, Na⁺, K⁺), Ba(L^I,III,IV)₂, and BaL^V have been synthesized and investigated. Compounds NaL^I,II quantitatively drop out as a deposit in ethanol medium, allowing the separation of Na⁺ and K⁺ cations. This effect is not displayed for the other compounds. The crystal structures of HL^III and the solvate of the composition [K(Me₂CO)L^III] have been investigated by X-ray crystallography.     

Ferromagnetic exchange coupling in a new bis(μ-chloro)-bridged copper(II) Schiff base complex: Synthesis,structure, magnetic properties and catalytic oxidation of cycloalkanes

A new (μ-chloro)-bridged complex [Cu(HL)Cl]₂ · H₂O (1) with the Schiff base ligand H₂L, [2-((E)-(2-hydroxyethylimino)methyl)-4-bromophenol], has been synthesized and characterized by elemental analysis, IR, UV–Vis and EPR spectroscopic studies. X-ray diffraction studies show that 1 is a binuclear Cu^II complex with a pair of chlorine atoms bridging the copper atoms in a central Cu₂Cl₂ core. Each copper atom in 1 adopts a distorted square-pyramidal geometry with the imine nitrogen atom, alkoxy and phenoxy oxygen atoms from the Schiff base ligand and a bridging chlorine atom constructing the basal plane, while the apical position of the pyramid is occupied by the other bridging chlorine atom. Variable temperature susceptibility measurements show that complex 1 presents the highest ferromagnetic coupling [J = +43.2(5) cm⁻¹] reported till date in any doubly chloro-bridged Cu^II dimer, and a weak interdimer antiferromagnetic coupling [J′ = -0.276(8) cm⁻¹]. The complex also exhibits high catalytic activity towards the oxidation of hydrocarbons using H₂O₂ as terminal oxidant.