First example of the planar rectangular 18-nuclear nickel(II) hydroxo complex with n-(2-pyridylmethyl)iminodipropionic acid

A planar rectangular cluster Ni₁₈ (I) was obtained from N-(2-pyridylmethyl)iminodipropionic acid (II). The crystal structure of complex I was determined by X-ray diffraction. Complex I is built from the octanuclear planar framework (III) of the nickel(II) hydroxo complex (Ni...Ni 2.976–3.092 Å), four nickel chelates with the corresponding acid (IV), which are coplanar with the framework and are on both its sides (Ni...Ni, 2.938–3.188 Å), four hydroxo complexes, and two mixed chloro chelates V), which are not coplanar with the framework (Ni...Ni, 3.141 and 3.181 Å). In the chelate parts of complex I, the organic ligand is hexadentate because of bridging bonds; the coordination polyhedroLn of the metal center is a distorted square bipyramid (4 + 2).     

Synthesis,Characterization, and Reactivity of a Series of Homo- and Hetero-dinuclear Complexes based on an Asymmetric FloH Ligand System

In a previous communication we reported the site-directed generation of a heterodinuclear Fe^IIICu^II complex ( 1 ) by using an asymmetric dinucleating ligand FloH. The iron(III) ion was introduced first on the preferential metal-binding site of the ligand that led to the formation of the thermodynamically favored five-membered chelate ring upon metal-binding. Copper(II) was introduced in the next step. The stepwise metalation strategy reported previously has now been extended to synthesize a series of heterodinuclear Fe^IIIM^II [M = Mn ( 2 ), Fe ( 3 ), Co ( 4 ), and Ni ( 5 )] and Fe^IICu^I ( 1a ) as well as the homodinuclear Cu^ICu^I ( 6 ) complexes. The complexes were characterized by X-ray crystallography (except for 1a and 6 ), and by a limited number of spectroscopic methods. Complex 1 with a labile solvent binding site at Fe^III reacted with H₂O₂ to form a transient intermediate that showed reactivity typical of metal peroxide complexes. The metal centers in the complexes 2 – 5 are coordinatively saturated, and hence they showed no reactivity with H₂O₂. Complex 1a reacted with O₂ via an intermolecular pathway to form a μ-oxo bridged tetrameric complex 1b , which was structurally characterized. This is in contrast to the homodinuclear Cu^ICu^I and heme Fe^IICu^I cores, which prefer an intramolecular pathway for O₂ activation.     

Crystal structures and enhanced luminescence of Zn(II) and Cd(II) complexes containing conjugated organic ligands

By self-assembly of delocalized organic ligands (L¹ and L²) with Cd(SCN)₂, ZnI₂ and Zn(NCS)₂, three luminescent complexes ZnI₂(L¹)₂ (I), [Cd(L¹)₂(μ_1,3-SCN)₂] _n (II) and Zn(NCS)₂(L²)₂ (III) were obtained (L¹ = 2-{5,5-dimethyl-3-[2-(pyridine-4-yl)ethenyl]cyclohex-2-enylidene}propanedinitrile and L² = 2-{5,5-dimethyl-3-[2-(pyridine-3-yl)ethenyl]cyclohex-2-enylidene}propanedinitrile). The structures of the complexes were determined by single crystal X-ray diffraction analysis (CIF files CCDC nos. 1406116 (I), 1406115 (II), and 1400360 (III)). In complex I, Zn(II) is coordinated by two functional organic ligands and two I^– ions, to form a I₂N₂ distorted tetrahedral geometry. In 1D coordination polymer II, the Cd(II) centers show six-coordinated geometries, two organic ligands and four SCN^– ions involve in coordination with each Cd(II) center. The thiocyanate groups show μ_1,3-SCN bridging coordination modes and the adjacent Cd(II) ions are bridged by double μ_1,3-SCN ions to form an infinite chain. In complex III, Zn(II) is coordinated by two functional organic ligands and two NCS^– groups, to form a N₄ distorted tetrahedral geometry. Compared with the free ligands, the complexes show superior luminescent property with red-shift and enhancement of fluorescence intensity.     

Ni(II) complexes with optically active bis(menthane), pinano-para-menthane ethylenediaminodioximes and pinano-para-menthane, bis(pinane) propylenediaminodioximes: Synthesis, structures, and properties

Reactions of Ni(NO₃)₂ · 6H₂O) in EtOH(iso-PrOH) with optically active bis(menthane) ethylene-diaminodioxime (H₂L¹), pinano-para-menthane ethylenediaminodioxime (H₂L²), pinano-para-menthane propylenediaminodioxime (H₂L³) and bis(pinane) propylenediaminodioxime (H₂L⁴) were used to synthesize [Ni(H₂L¹)NO₃[NO₃ · 2H₂O (I), [Ni(HL²)]NO₃ (II), [Ni(HL³)]NO₃ (III), and [Ni(HL⁴)]NO₃ (IV). X-ray diffraction study of paramagnetic complex I (μ_eff = 3.04 μB and diamagnetic complexes II and III revealed their ionic structures. A distorted octahedral polyhedron N₄O₂ in the cation of complex I is formed by the N atoms of tetradentate cycle-forming ligand, i.e., the H₂L¹ molecule, and the O atoms of the NO ₃ ^? anion acting as a bidentate cyclic ligand. In the cations of complexes II and III, containing a pinane fragment, the coordination core NiN₄ has the shape of a distorted square formed on coordination of tetradentate cycle-forming ligands, i.e., anions of the starting dioximes. The structure of diamagnetic complex IV is likely to be similar to the structures of complexes II and III.     

Synthesis and structural properties of thiapyridinophane and its complex with Ni(II) and Ag(I)

The 2,11-dithia[3.3](3,5)pyrdinophane (L¹) has been synthesized by a new method and characterized by ¹H NMR, which is used to form coordination complexes C₁₄H₁₄N₄O₆S₂Ni (I) by addition of Ni²⁺ cation and C₁₄H₁₄N₃O₃S₂Ag (II) by addition of Ag⁺ cation. 2,11,20-Trithia[3.3.3](3,5)pyridinophane (L²) and 2,11,20,29-tetrathia[3.3.3.3](3,5)pyridinophane (L³) have also been synthesized as by-products. Single-crystal X-ray analysis reveals that the conformation of the L¹ is syn(boat-chair), complexes I and II also adopt syn(boat-chair) (CIF files CCDC nos. 1400332 (I) and 700724 (II)). While in I, Ni(II) is coordinated with L¹ with two nitrogen and four oxygen atoms, in II, Ag(^I) is coordinated with L¹ by two nitrogen and two sulfur atoms came from four ligands. In complexes I and II, the formation of three-dimensional structure depends on π???π stacking and hydrogen bonds.     

Synthesis and structure of iron(III) complexes with a new ligands based on Girard’s reagent

Condensation of 5-bromosalicylaldehyde with Girard’s reagent T yields a new ligand in the form of a salt, 5-bromosalicylaldehyde (carboxymethyl)trimethylammonium chloride hydrazone (5-BrH₂SalGT)Cl (I). Ligand I is readily soluble in water and reacts with iron chloride to give the complex [Fe(5-BrSalGT)Cl₂] (II). Treatment of II with KCNS leads to the compound [Fe(5-BrSalGT)(NCS)₂(H₂O)] (III). At any ratio of the initial reagents, only complexes with the ratio metal: ligand = 1: 1 are isolated. Comparison of the structural data for compounds I–III shows that ligand I is deprotonated in the course of complex formation and is coordinated in the anionic form. Its conformational rearrangement is minimal and involves only a change in the orientation of the terminal group N(CH₃)₃. In complexes II and III, ligand I is coordinated to the metal ion through the ONO donor atoms. The structures of the complexes with different acido ligands are significantly different. Although the complexes contain each two inorganic anions, their coordination polyhedra differ from each other. In II, the iron atom is at the center of a trigonal bipyramid, whereas in III the iron atom has a tetragonal-bipyramidal environment due to the extra coordination of a water molecule. In both complexes, the iron atom is in the high-spin state: at room temperature, μ_eff is 5.86 and 5.81 μ_B for II and III, respectively. Complexes II and III are ordinary paramagnets down to 2 K.     

Dipyridyl-type ligand-directed assembly of three cobalt(II) coordinated polymers based on carboxyphenylpropionate

A series of Co(II)-H₂Cpp coordination polymers incorporating different auxiliary ligands, [Co(Cpp)(Phen)(H₂O)] (I), {[Co(Bipy)(H₂O)₄](Cpp)} _n (II), and [Co(Cpp)(Bds)(H₂O)] _n (III) (H₂Cpp = 3-(4-carboxyphenyl)propionic acid, Phen = 1,10-phenanthroline, Bipy = 4,4′-bipyridyl, and Bds = 4,4′-bipyridyl sulfide), were synthesized by the hydrothermal reaction and characterized by single crystal X-ray diffraction, elemental analysis, IR, and TG. Three complexes display from 0D to 1D different structural features under the regulation of distinguishing dipyridyl-type coligands. Complex I possesses a binuclear Co(II) motif constructed by H₂Cpp and Phen, which further developing a zipper-like 2D layer via H-bonded and π-π stacking interactions. Complex II displays straight Bipy-bridging 1D chain, and further forming a 3D supramolecular structure by hydrogen-bonded interactions. Complex III exhibits 1D double-chain collectively jointed by Cpp and Bds, which further interlinked into a 3D supramolecular architecture by H-bonded interactions.     

Effect of solvent on the crystal structures of copper(II) complexes based on 4′-(4-methoxyphenyl)-2,2′:6′,2″-terpyridine and 4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine

Four homoleptic copper(II) complexes, [Cu(Meophtpy)₂](ClO₄)₂ (Meophtpy = 4′-(4-methoxylphenyl)- 2,2′:6′,2″-terpyridine) (I), [Cu(Meophtpy)₂](ClO₄)₂ · 2H₂O (II), [Cu₂(m-Clphtpy)₄](ClO₄)₄ (m-ClPhtpy = 4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine) (III), and [Cu₂(m-ClPhtpy)₄](ClO₄)₄ (IV) have been synthesized by hydrothermal methods and characterized by IR, elemental analysis and single crystal X-ray diffraction (CIF files CCDC nos. 963375 (I), 885457 (II), 963377 (III), and 963376 (IV)). Complex II is a polymorph of I and complex IV is a polymorph of III. All these complexes are obtained with 95% ethanol solution or 50% ethanol solution and the solvent control on the crystallization are obviously found. In all complexes, the face-to-face interactions between pyridyl rings or phenyl rings facilitate the construction of 3D network in the crystal in addition to hydrogen bonds. The fluorescence properties of these complexes have been investigated.     

Synthesis, crystal structures, and properties of inorganic-organic hybrid complexes constructed from copper(II) macrocyclic fragment

Reaction of a macrocyclic copper(II) complex [Cu(L)](ClO₄)₂ · 3H₂O (I) (L = 1,3,10,12,16,19-hexaazatetracyclotetracosane) with a hexapod carboxylate ligand H₆TTHA (H₆TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid) and a tripod carboxylate ligand H₃TATB (H₃TATB = 4,4′,4″-S-triazine-2,4,6-triyl-tribenzoic acid) yielded two mononuclear copper(II) complexes [Cu(L)][H₄TTHA] · 4H₂O (II) and [Cu(L)][HTATB] · 4H₂O (III). The complexes I–III have been structurally characterized. The crystal structures of complexes II and III show the copper(II) ion has a distorted pentacoordinate square-pyramidal geometry with two secondary and two tertiary amines from the macrocyclic complex [Cu(L)]²⁺ and one oxygen atom from the carboxylate ligand group at the axial position. The UV-Vis spectra are utilized to discuss the hydrolysis of the complex II.     

Synthesis,structure, and optical properties of lanthanum(III), cerium(III), praseodymium(III), and nickel(II) heterometallic complexes with glycine

New cluster complexes of lanthanides(III) and nickel(II) [Ln{Ni(Gly)₂}₆]³⁺[Ln(NO₃)₆]^3– have been synthesized, where Ln = La (I), Ce (II), and Pr (III); and Gly is glycinate. The structures of compounds I–III are determined by X-ray diffraction. The icosahedral cavity in the complex cation, where the lanthanide ion resides, has a fixed size independent of the nature of the central Ln(III) ion. In the complex anion, on the contrary, the Ln–O distances naturally decrease from La(III) to Pr(III). The optical properties of cationanion complexes I–III are studied. Based on the assignment in the electronic absorption spectra of the complexes, it is shown that the absorption bands are caused by d–d electronic transitions.     

Crystal structures and luminescence of a series of cadmium(II) complexes based on isophorone derivative containing imidazolyl

Three new complexes, [CdL₂(CH₃COO)₂(H₂O)₂] (I), CdL₂Br₂ (II), CdL₂I₂ (III), have been successfully synthesized by self-assembly of corresponding metal salts with (E)-2-(3-(4-(1H-imidazole-1-yl)styryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile (L). The structures of the complexes were determined by single crystal X-ray diffraction analysis (CIF file CCDC nos. 957831 (I), 957792 (II), 957832 (III)). In complex I, central metal is six-coordinated and the crystal packing shows a 3D supramolecular framework. Complexes II and III display the similar 2D supramolecular structures in which the central metals are four-coordination. The luminescent properties were investigated.     

Synthesis and crystal structures of two new Schiff base cobalt(II) and nickel(II) complexes

The Schiff base ligand (HL) obtained from phenylmethanamine and 5-methoxysalicylaldehyde are used as ligands for Co(II) and Ni(II) resulting in complexes [Co(L)₂] (I) and [Ni(L)₂] (II), and their solid state structures were determined by X-ray crystallography. In both complexes, weak interactions play an important role in the molecular self-assembly. Complex I was stacked up to the 2D layers by C-H…O hydrogen bonds and C-H…π interactions. In contrast, complex II was extended into 2D sheet by C-H…O hydrogen bonds, the C-H…π interactions, and edge-to-face interactions.     

Synthesis, characterization, and X-ray crystal structures of copper(II) and nickel(II) complexes with Schiff base

New copper(II) complexes, [Cu₂L¹L²] · ClO₄ (I) and [Ni(L³)₂] (II), where L¹ is the monoanionic form of 2-[1-(2-emthylaminoethylimino)ethyl]phenol, L² is the dianionic form of N,N′-ethylene-bis(2-hydroxyacetophenonylideneimine), L³ is the mono-anionic form of 2-(1-iminoethyl)phenol, were prepared and characterized using elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction. In complex I, the Cu(1) atom is coordinated by the NNO tridentate ligand L¹ and the two phenolate O atoms of L², forming a square pyramidal geometry. The Cu(2) atom in complex I is coordinated by the NNOO tetradenate ligand L², forming a square planar geometry. The Ni atom in complex II is coordinated by two phenolate O and two imine N atoms from two ligands L³, forming a square planar geometry. In the crystal structure of I, the perchlorate anions are linked to the dinuclear copper(II) complex cations through intermolecular N-H...O hydrogen bonds. In the crystal structure of II, the mononuclear nickel complex molecules are linked through intermolecular N-H...O hydrogen bonds, forming a trimer.     

pH-dependent syntheses and crystal structures, characterizations, and DFT calculations of complexes with 2,2′-biimidazole and terephthalic acid ligands

The divalent transition metal complexes [Zn(L)₂(H₂O)₂](Tere) (I), [Cd(L)₂(H₂O)₂](Tere]) (II) and [Cd(L)₂(HTere)₂] (III) (L = 2,2’-biimidazole, Tere = terephthalate) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectrum, thermal analysis and single-crystal X-ray diffraction analysis. Complexes II and III have the same starting materials but possess different frame-works and are prepared from H₂Biim and H₂Tere under hydrothermal conditions with different pH values. The crystal structures show I and II have the same coordination circumstances and are coordinated by two H₂O molecules and two neutral bidentate 2,2′-biimidazole ligands. The terephthalate acts as the counter anion. In contrast, complex III contains protonated carboxylate groups coordinated to the metal centre to give neutral species. Furthermore, based on the optimized structures, molecular frontier orbitals, Mulliken charges and IR spetra of complex I and III are investigated by density functional theory. Calculated results show that the energy gap (ΔE _L-H) between HOMO and LUMO of complex III is bigger than that of I. It is revealed that complex III is more stable, and this calculated estimation corresponds with experimental analysis of TGA curves.     

Microwave-assisted synthesis,crystal structures,and in vitro antibacterial studies of zinc(II) and nickel(II) complexes with Schiff bases

The syntheses of a mononuclear zinc(II) complex [ZnCl(L¹)(Amp)] (I) and a mononuclear nickel(II) complex [Ni(L²)(HL²)](BF₄) · 0.5H₂O (II) (HL¹ = 4-methyl-2-[(4-methylpyridin-2-ylimino) methyl]phenol, HL² = 4-methyl-2-[(pyridin-2-ylmethylimino)methyl]phenol; Amp = 2-amino-4- methylpyridine) were prepared under microwave irradiation. The complexes were characterized by a combination of elemental analyses, and IR and electronic spectra. Their structures were further confirmed by single crystal X-ray crystallography (СIF files CCDC nos 1437737 (I), 1437738 (II)). The Zn atom in the monomeric complex I is in tetrahedral coordination. The Ni atoms in the dimeric complex II are in octahedral coordination. Crystals of the complexes are stabilized by hydrogen bonds. In order to evaluate the biological activity of the complexes, in vitro antibacterial against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa was assayed. The complexes have strong activity against Bacillus subtilis.     

Stability and structure in solution of potassium and barium complexes with N,N’-diaryldiaza-18-crown-6: Crystal structure of N,N’-Bis(4-dimethylaminophenyl)diaza-18-crown-6 and its complex with barium perchlorate

It has been shown that N,N’-diaryldiaza-18-crown-6 ethers with p-dimethylamino-and p-methoxy groups in the benzene ring (aryl is 4-Mc₂NC₆H₄) (I) and 4-MeOC₆H₄ (II) form complexes with potassium and barium salts. The influence of these salts on the UV and ¹H NMR spectra of crown ethers I and II has been studied. The stability constants (logβ) of the complexes increase in the series II · Ba(ClO₄)₂ (2.0), I · Ba(ClO₄)₂ (2.3), II · KBr (2.8), I · KBr (3.0). N,N’-bis(4-dimethylphenylamine)diaza-18-crown-6 (L, I) and its complex with barium perchlorate Ba(ClO₄)₂ · L (III) are characterized by X-ray crystallography. The crystals of I are monoclinic: a = 13.778(2) Å, b = 5.9731(9) Å, c = 17.542(3) Å, β = 106.65(1)°, V = 1383.1(4) ų, Z = 2, space group P2₁/n, R = 0.0374 for 990 reflections with I > 2σ(I). The crystals of III are monoclinic: a = 17.275(4) Å, b = 8.017(2) Å, c = 26.935(4) Å, β = 100.47(2)°, V = 3669(1) ų, Z = 4, space group C2/c, R = 0.0320 for 1897 reflections with I > 2σ(I). The molecules of I and III are centrosymmetric. In III, the Ba atom is in the center of substituted diaza-18-crown-6 (DA18C6). The Ba atom is coordinated by all six donor atoms of diaza-18-crown-6 (av. Ba-O, 2.779(3) Å; Ba-N, 3.004(4) Å) and four oxygen atoms of two asymmetrically bound perchlorate groups (Ba-O, 2.832(4) and 3.031(4) Å) arranged below and above the plane of substituted diaza-18-crown-6. The conformations of the macrocycle in free and coordinated L are different.     

Syntheses, structural determination, and binding studies of mononuclear nine-coordinate (EnH2)1.5[HoIII(Ttha)] · 4.5H2O and two dimensional unlimited network (EnH2)[HoIII(Egta)(H2O)]2 · 6H2O

Two novel complexes, (EnH₂)_1.5[Ho^III(Ttha)] · 4.5H₂O (I) (En = ethylenediamine and H₆Ttha = triethylenetetramine-N,N,N′,N″,N?,N?-hexaacetic acid) and (EnH₂)[Ho^III(Egta)(H₂O)]₂ · 6H₂O (II) (H₄Egta = ethyleneglycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid), were synthesized and their crystal structures were determined by single crystal X-ray diffraction techniques. Complex I has a nine-coordinate mononuclear structure with distorted tricapped trigonal prismatic conformation and crystallizes in the monoclinic crystal system with P2/n space group. The crystal data are as follows: a = 17.7541(18), b = 9.6810(10), c = 22.166(2) Å, β = 118.913(2)°, and V = 3335.0(6) ų. Complex II has a mononuclear nine-coordinate structure with pseudo-monocapped square antiprismatic conformation and crystallizes in the monoclinic crystal system with P2₁/n space group. The crystal data are as follows: a = 12.978(8), b = 12.685(8), c = 14.905(9) Å, β = 105.333(7)°, and V = 2366(2) ų. In I, there are two types of EnH ₂ ²⁺ anions. They connect to [Ho^III(Ttha)]^3? by hydrogen bonds leading to the formation of 3D pore structure along z axis. In II, EnH ₂ ²⁺ cation connects three adjacent [Ho^III(Egta)(H₂O)]^? complex anions through hydrogen bonds, these hydrogen bonds lead to the formation of 2D network structure in [101] plane. The results showed that ligand structures play a crucial role in crystal and molecular structure of their complexes. In addition, the protonated (EnH ₂ ²⁺ ) cations conjugating to [Ho^III(Ttha)]^3? and [Ho^III(Egta)(H₂O)]^? complex anions are reviewed, which act as an important beginning for study of Ho(III) complexes conjugating with other various amino and heterocyclic biomolecule.     

Catalase activity of cobalt(II) complexes with N,N,N′,N′-tetrasubstituted thiocarbamoylsulfenamides

On the base of the kinetic and activation parameters of the hydrogen peroxide decomposition in the presence of chelates of CoX₂ salts (X = Cl, Br, I, NCS) with N,N,N′,N′-tetrasubstituted thiocarbamoylsulfenamides containing exocyclic (out-of-chelate) fragments of dimethylamine (I), piperidine (II), and piperazine (III) the nature of acido-ligands influence on catalase activity of complexes I–III was revealed, depending on the structure and composition of the chelating ligand. Mononuclear complexes I(Br) and II(Br) can transform into 10-membered binuclear macrochelate intermediates.     

Spectroelectrochemistry and localization of added electrons in ruthenium (II) mixed-ligand complexes

The ruthenium (II) mixed-ligand complexes cis-[Ru(bpy)₂(NCS)₂] (I), [Ru(bpy)₂(pn)]²⁺ (II) and [Ru(bpy)₂(phen)]²⁺ (III) (bpy, 2,2′-bipyridine; pn, 1,2-diaminopropane; phen, 1,10-phenanthroline) were subjected to two (for I and II), and three (for III) stepwise, one-electron reductions, and one-electron oxidations (all fully reversible); the products were studied in situ by solution UV—vis-near IR spectroscopy. The first two reductions took place in all cases on separate bpy ligands, while the third reduction of III took place on phen. Bands of the reduced species in the near IR—vis region are observed and assigned to anion radical ligands. Novel features of the LMCT bands of the oxidized species are presented and discussed.     

High-spin adducts of redox active 2,4,6,8-tetrakis(<Emphasis Type="Italic">tert</Emphasis>-butyl)phenoxazin-1-one with tetrahedral cobalt(II) complexes

The complex formation between redox active 2,4,6,8-tetrakis(tert-butyl)phenoxazin-1-one (L) and four-coordinate Co(II) complexes, resulting in six-coordinate adducts (I) (C₇₇H₈₂N₁₂O₅Co) and (II) (C₃₈H₄₁NO₆F₁₂Co) was studied. High-spin structure of the formed cobalt adducts I and II (hs-Co^II–BQ) was established by X-ray diffraction analysis and magnetochemistry methods. Adducts I and II are stable over a wide temperature range (5–300 K) and are not involved in the redox process giving low-spin adducts (ls-Co^III–SQ) studied previously.