Diaqua{6,6′‐dimethoxy‐2,2′‐[propane‐1,3‐diylbis(nitrilomethylidyne‐N)]diphenolato‐O,O′}nickel(II)

In the title compound, [Ni(C₁₉H₂₀N₂O₄)(H₂O)₂], the Ni atom has a distorted octahedral coordination geometry in which the tetradentate Schiff base ligand acts as a cis‐N₂O₂ donor defining an equatorial plane, and water mol­ecules occupy the axial positions. The two parts of the mol­ecule are related by a mirror plane that passes through the Ni atom and is perpendicular to the equatorial plane. The angular distortions from normal octahedral geometry are in the range 1–6°, and the equatorial plane, defined by the donor atoms of the Schiff base, is almost square planar. The six‐membered ring comprising the Ni, the imine N and the propyl­ene C atoms adopts a half‐chair conformation. The Ni—O [2.017 (2) Å] and Ni—N [2.071 (2) Å] distances are within the ranges expected for high‐spin octahedral nickel complexes.     

Self‐Assembly,Spectroscopic and Electrochemical Studies of Nickel(II)‐4,8‐Diazaundecanediamide Complex

The self‐assembly of NiCl₂·6H₂O with a diaminodiamide ligand 4,8‐diazaundecanediamide (L‐2,3,2) gave a [Ni(C₉H₂₀N₄O₂)(Cl)(H₂O)] Cl·2H₂O ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction analysis. Structural data for 1 indicate that the Ni(II) is coordinated to two tertiary N atoms, two O atoms, one water and one chloride in a distorted octahedral geometry. Crystal data for 1: orthorhombic, space group P 21nb, a = 9.5796(3) Å, b = 12.3463(4) Å, c = 14.6305(5) Å, Z = 4. Through NH···Cl–Ni (H···Cl 2.42 Å, N···Cl 3.24 Å, NH···Cl 158°) and OH···Cl–Ni contacts (H···Cl 2.36 Å, O···Cl 3.08 Å, OH···Cl 143°), each cationic moiety [Ni(C₉H₂₀N₄O₂) (Cl)(H₂O)]⁺ in 1 is linked to neighboring ones, producing a charged hydrogen‐bonded 1D chainlike structure. Thermogrametric analysis of compound 1 is consistent with the crystallographic observations. The electronic absorption spectrum of Ni(L‐2,3,2)²⁺ in aqueous solution shows four absorption bands, which are assigned to the ³A_2g → ³T_2g, ³T_2g → ¹Eg, ³T_2g → ³T_1g, and ³A_2g → ³T_1g transitions of triplet‐ground state, distorted octahedral nickel(II) complex. The cyclic volammetric measurement shows that Ni²⁺ is more easily reduced than Ni(L‐2,3,2)²⁺ in aqueous solution.     

One‐dimensional copper(II) coordination polymers based on 1,3‐bis(pyridin‐4‐yl)propane and diimine ligands

Two one‐dimensional (1D) coordination polymers (CPs), namely catena‐poly[[[aqua(2,2′‐bipyridine‐κ²N,N′)(nitrato‐κO)copper(II)]‐μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ²N:N′] nitrate], {[Cu(NO₃)(C₁₀H₈N₂)(C₁₃H₁₄N₂)(H₂O)]·NO₃}_n ( 1 ), and catena‐poly[[[aqua(nitrato‐κO)(1,10‐phenanthroline‐κ²N,N′)copper(II)]‐μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ²N:N′] nitrate], {[Cu(NO₃)(C₁₂H₈N₂)(C₁₃H₁₄N₂)(H₂O)]·NO₃}_n ( 2 ), have been synthesized using [Cu(NO₃)(NN)(H₂O)₂]NO₃, where NN = 2,2′‐bipyridine (bpy) or 1,10‐phenanthroline (phen), as a linker in a 1:1 molar ratio. The CPs were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single‐crystal X‐ray structure determination. The 1,3‐bis(pyridin‐4‐yl)propane (dpp) ligand acts as a bridging ligand, leading to the formation of a 1D polymer. The octahedral coordination sphere around copper consists of two N atoms from bpy for 1 or phen for 2 , two N atoms from dpp, one O atom from water and one O atom from a coordinated nitrate anion. Each structure contains two crystallographically independent chains in the asymmetric unit and the chains are linked via hydrogen bonds into a three‐dimensional network.     

SYNTHESIS AND CHARACTERIZATION OF DIAQUA(3-pTOLYLIMINO-2-BUTANONE OXIMATO)(3-p-TOLYLIMINO-2-BUTANONE OXIME)NICKEL(II) PERCHLORATE

Abstract

[Ni(L^?1)(HL)(H₂O)₂].ClO₄ with a Schiff base ligand L (HL = 3-p-tolylimino-2-butanone oxime) was prepared and structurally characterized by IR, cyclic voltammetry and X-ray diffraction methods. The nickel atom has distorted octahedral coordination consisting of four nitrogen atoms and two oxygen atoms. The equatorial plane is formed by two oxime nitrogen atoms and two imine nitrogen atoms of two Schiff base ligand (L^?1 and HL) with Ni‐ N bond distances between 2.01(1) and 2.11(1)Å. Water oxygen atoms occupy axial positions with Ni‐ O bond distances of 2.06(1) and 2.15(1) Å. The oxime groups in the Schiff base ligands are coordinated to Ni atom through their nitrogen atoms. One asymmetric intramolecular hydrogen bridge between the two oxime groups is found in the title complex.     

Cobalt(II) and nickel(II) complexes of isoquinoline‐1‐carboxylate

trans‐Di­aqua­bis­(iso­quinoline‐1‐carboxyl­ato‐κ²N,O)­cobalt(II) dihydrate, [Co(C₁₀H₆NO₂)₂(H₂O)₂]·2H₂O, and trans‐di­aqua­bis­(iso­quinoline‐1‐carboxyl­ato‐κ²N,O)­nickel(II) dihydrate, [Ni(C₁₀H₆NO₂)₂(H₂O)₂]·2H₂O, contain the same isoquinoline ligand, with both metal atoms residing on a centre of symmetry and having the same distorted octahedral coordination. In the former complex, the Co—O(water) bond length in the axial direction is 2.167 (2) Å, which is longer than the Co—O(carboxylate) and Co—N bond lengths in the equatorial plane [2.055 (2) and 2.096 (2) Å, respectively]. In the latter complex, the corresponding bond lengths for Ni—O(water), Ni—O(carboxylate) and Ni—N are 2.127 (2), 2.036 (2) and 2.039 (3) Å, respectively. Both crystals are stabilized by similar stacking interactions of the ligand, and also by hydrogen bonds between the hydrate and coordinated water molecules.     

Solvolthermal Syntheses and Crystal Structures of Three Linear Trinuclear Schiff Base Complexes of Zinc(II) and Cadmium(II)

Three linear trinuclear Schiff base complexes, {Zn[Zn(CH₃COO)(C₁₇H₁₆N₂O₂)]₂} ( 1 ), {Zn[Zn(CH₃COO)(C₂₅H₂₀N₂O₂)]₂} ( 2 ), and {Cd[Cd(CH₃COO)(C₁₈H₁₈N₂O₂)]₂} ( 3 ), were synthesized for the first time under solvolthermal conditions. Their structures have been characterized by elemental analyses, X-ray single crystal determinations, and infrared spectroscopy. There are three bridges across the M-M atom pairs (M is Zn for 1 and 2 , or Cd for 3 ) in each complex, involving two O atoms of a Schiff base ligand (N,N′-bis(salicylidene)-1, 3-propanediaminate (SALPD^2-) for 1 , N, N′-bis(2-hydroxy-naphthalmethenylimino)-1, 3-propanediaminate (NAPTPD^2-) for 2 , and N,N′-bis-(salicylidene)-1,4-butanediaminate (SALBD^2-) for 3 ), and an O-C-O moiety of a μ-acetato group. In each of the complexes, the central M²⁺ ion is located on an inversion center and has a distorted octahedral coordination involving four bridging O atoms from two Schiff base ligands in the equatorial plane and one O atom from each bridging acetate group in the axial positions. The coordination around the terminal M²⁺ ions is irregular square pyramidal, with two O atoms and two N atoms of the Schiff base ligand in the basal plane and one O atom from an acetate group in the apical position. The acetate bridges linking the central and terminal M²⁺ ions are mutually trans. The M…M distances are 3.050(3) Å in 1 , 3.139(2) Å in 2 , and 3.287(6) Å in 3 .     

Two nickel(II) bis[(pyridin‐2‐yl)methyl]amine complexes with homophthalic and benzene‐1,2,4,5‐tetracarboxylic acids

Two new Ni^II complexes involving the ancillary ligand bis[(pyridin‐2‐yl)methyl]amine (bpma) and two different carboxylate ligands, i.e. homophthalate [hph; systematic name: 2‐(2‐carboxylatophenyl)acetate] and benzene‐1,2,4,5‐tetracarboxylate (btc), namely catena‐poly[[aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)]‐μ‐2‐(2‐carboxylatophenyl)aceteto‐κ²O:O′], [Ni(C₉H₆O₄)(C₁₂H₁₃N₃)(H₂O)]_n, and (μ‐benzene‐1,2,4,5‐tetracarboxylato‐κ⁴O¹,O²:O⁴,O⁵)bis(aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) bis(triaqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) benzene‐1,2,4,5‐tetracarboxylate hexahydrate, [Ni₂(C₁₀H₂O₈)(C₁₂H₁₃N₃)₂(H₂O)₂]·[Ni(C₁₂H₁₃N₃)(H₂O)₃]₂(C₁₀H₂O₈)·6H₂O, (II), are presented. Compound (I) is a one‐dimensional polymer with hph acting as a bridging ligand and with the chains linked by weak C—H...O interactions. The structure of compound (II) is much more complex, with two independent Ni^II centres having different environments, one of them as part of centrosymmetric [Ni(bpma)(H₂O)]₂(btc) dinuclear complexes and the other in mononuclear [Ni(bpma)(H₂O)₃]²⁺ cations which (in a 2:1 ratio) provide charge balance for btc⁴⁻ anions. A profuse hydrogen‐bonding scheme, where both coordinated and crystal water molecules play a crucial role, provides the supramolecular linkage of the different groups.     

Synthesis and Crystal Structure of Two Succinato‐Bridged Macrocyclic Nickel(II) Complexes

Two dinuclear succinato‐bridged nickel(II) complexes [Ni(RR‐L)]₂(μ‐SA)(ClO₄)₂ ( 1 ) and [Ni(SS‐L)]₂(μ‐SA)(ClO₄)₂ ( 2 ) (L = 5, 5, 7, 12, 12, 14‐hexamethyl‐1, 4, 8, 11‐tetraazacyclotetradecane, SA = succinic acid) were synthesized and characterized by EA, Circular dichroism (CD), as well as IR and UV/Vis spectroscopy. Single crystal X‐ray diffraction analyses revealed that the Ni^II atoms display a distorted octahedral coordination arrangement, and the succinato ligand bridges two central Ni^II atoms in a bis bidentate fashion to form dimers in 1 and 2 . The monomers of {[Ni(RR‐L)]₂(μ‐SA)}²⁺ and {[Ni(SS‐L)]₂(μ‐SA)}²⁺ are connected by O–H ··· O and N–H ··· O hydrogen bonds into a 1D right‐handed and left‐handed helical chain along the b axis, respectively. The homochiral natures of 1 and 2 are confirmed by the results of CD spectroscopy.     

Intermolecular Interaction and Magnetic Coupling Mechanism of a Mononuclear Nickel(II) Complex

The mononuclear complex [Ni(HOphen)(OSO₃)(H₂O)₃] · 5H₂O (HOphen = 1, 10‐phenanthrolin‐2‐ol) was prepared and its single structure was determined by X‐ray crystallography. In this complex, the Ni^II ion has a distorted octahedral arrangement. Crystal structure analysis shows that two kinds of π–π stacking interactions and C–H ··· O short contact intermolecular interactions exist among the adjacent complexes. Fitting to the variable‐temperature magnetic susceptibility data gave the magnetic coupling constant, 2J = –0.98 cm^–1. Theoretical calculations, based on density functional theory (DFT) coupling with the broken‐symmetry approach (BS), revealed that the π–π stacking magnetic coupling pathways resulted in weak ferromagnetic interactions with 2J = 4.86 cm^–1 and 2J = 4.16 cm^–1, respectively, for the adjacent Ni^II ions with separations of 8.568(19) Å and 8.749(32) Å, respectively; whereas the magnetic coupling pathway of the C–H ··· O short contact intermolecular interaction led to a weak antiferromagnetic interaction with 2J = –17.62 cm^–1 for the adjacent Ni^II ions with a separation of 10.291(26) Å. The ferromagnetic coupling sign can be explained by the McConnell I spin‐polarization mechanism.     

Syntheses,Crystal Structures,and Antibacterial Activities of Four Schiff Base Copper(II), Zinc(II), and Cadmium(II) Complexes Derived from 2‐[(2‐Dimethylaminoethylimino)methyl]phenol

Four Schiff base complexes, [Zn₂L₂(NCS)₂] ( 1 ), [Cd₂L₂(NCS)₂]_n ( 2 ), [Zn₄L₂(N₃)₂Cl₄(OH₂)(CH₃OH)] ( 3 ), and [Cu₄L₂(N₃)₂Cl₄(OH₂)(CH₃OH)] ( 4 ) (where L = 2‐[(2‐dimethylaminoethylimino)methyl]phenol), were synthesized and characterized by elemental analyses, infrared spectroscopy, and single crystal X‐ray determinations. Both 1 and 2 are structurally similar polynuclear complexes. In 1 , each Zn atom has a slightly distorted square‐pyramidal coordination configuration. In the basal plane, the Zn atom is coordinated by one O and two N atoms of one L, and by one O atom of another L. The apical position is occupied by one terminal N atom of a coordinated thiocyanate anion. The Zn···Zn separation is 3.179(3) Å. While in 2 , the Cd1 atom is six‐coordinated in an octahedral coordination. In the equatorial plane, the Cd1 atom is coordinated by one O and two N atoms of one L, and by one O atom of another L. The axial positions are occupied by the terminal N and S atoms from two bridging thiocyanate anions. The coordination of Cd2 atom in 2 is similar to those of the zinc atoms in 1 . The Cd···Cd separation is 3.425(2) Å. Both 3 and 4 are novel tetra‐nuclear complexes. Each metal atom in the complexes has a slightly distorted square‐pyramidal coordination. The arrangements of the terminal metal atoms are similar, involving one O and two N atoms of one L ligand and one bridging Cl atom defining the basal plane, and one O atom of a coordinated water molecule or MeOH molecule occupying the apical position. The coordinations of the central metal atoms are also similar. The basal plane of each metal atom involves one O atom of one L ligand, one terminal Cl atom, and two terminal N atoms from two bridging azide groups. The apical position is occupied by a bridging Cl atom which also acts as a basal donor atom of the terminal metal atom. The Schiff base ligand and the four complexes showed high selectivity and antibacterial activities against most of the bacteria.     

Synthesis and characterization of a thioether Schiff base ligand and its metal complexes and crystal structure determination of the nickel(II) complex

Reactions of 1,2-di(o-aminophenylthio)ethane with 3-ethoxy-2-hydroxybenzaldehyde yield the new hexadentate N₂S₂O₂ donor thioether Schiff base 1,2-bis(2-((2-(thio)phenylimino)methyl)-6-ethoxyphenol)ethane (H₂L). Ni(II), Zn(II), Cd(II), and Hg(II) complexes of this ligand were prepared. Of these complexes, [NiL]·2H₂O has been structurally characterized by X-ray crystallography. The coordination geometry around Ni(II) was described as octahedral. Zn(II), Cd(II), and Hg(II) complexes and the Schiff base ligand have been characterized by CHN analyses, molar conductivity, UV–vis, FT-IR, ¹H, and ¹³C NMR spectroscopy.     

Synthesis,structures, and urease inhibition of nickel(II), zinc(II), and cobalt(II) complexes with similar hydroxy-rich Schiff bases

Four new nickel(II), zinc(II), and cobalt(II) complexes, [Zn(L¹)₂]?·?H₂O (1), [Ni(L¹)₂]?·?H₂O (2), [Ni(L²)₂] (3), and [Co(L³)₂]?·?H₂O (4), derived from hydroxy-rich Schiff bases 2-{[1-(5-chloro-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL¹), 2-{[1-(2-hydroxy-3-methoxyphenyl)methylidene]amino}-2-ethylpropane-1,3-diol (HL²), and 2-{[1-(5-bromo-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL³) have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray determination. Each metal in the complexes is six-coordinate in a distorted octahedral coordination. The Schiff bases coordinate to the metal atoms through the imino N, phenolate O, and one hydroxyl O. In the crystal structures of HL¹ and the complexes, molecules are linked through intermolecular O–H···O hydrogen bonds, forming 1-D chains. The urease inhibitory activities of the compounds were evaluated and molecular docking study of the compounds with the Helicobacter pylori urease was performed.     

Synthesis,crystal structure and antibacterial activity of manganese(III) and cobalt(III) complexes containing pentadentate Schiff bases of a common amine and thiocyanate

Abstract

Four new mononuclear Schiff base manganese(III) and cobalt(III) complexes viz. [Mn(L¹)(NCS)] (1), [Mn(L²)(NCS)] (2), [Co(L³)(NCS)] (3), and [Co(L⁴)(NCS)]·0.5CH₃OH·0.5H₂O (4), containing thiocyanate as a common pseudohalide ion are reported. The pentadentate Schiff base ligands H₂L¹, H₂L², H₂L³, and H₂L⁴ were obtained by the condensation of substituted salicylaldehydes with N-(3-aminopropyl)-N-methylpropane-1,3-diamine. The syntheses of the complexes have been achieved by the reaction of manganese(II) perchlorate or cobalt(II) perchlorate with the respective Schiff bases in the presence of thiocyanate in methanol medium. Complexes 1–4 have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1–4 adopt nearly similar structures containing the MN₄O₂ (M?=?Mn, Co) chromophore in which each central M(III) ion adopts a distorted octahedral geometry. Weak intermolecular H-bonding interactions are operative in these complexes to bind the molecular units. The antibacterial activity of 1–4 and their constituent Schiff bases has been tested against some common bacteria.     

Syntheses,Crystal Structures,and Antibacterial Activities of Four Schiff Base Complexes of Copper and Zinc

Four Schiff base complexes, [Cu₂(L1)₂(μ‐NCS)₂] ( 1 ), [Cu₂(L2)₂(μ‐N₃)₂] ( 2 ), Cu[Cu(CH₃COO)(L3)]₂ ( 3 ), and [Zn{Zn(C₃H₄N₂)(L3)}₂(NO₃)](NO₃) ( 4 ) (where L1 = 2‐[(pyridin‐2‐ylmethylimino)methyl]phenol, L2 = 1‐[(pyridin‐2‐ylmethylimino)methyl]naphthalen‐2‐ol, and L3 = bis(salicylidene)‐1, 3‐propanediamine), were synthesized and characterized by elemental analyses, infrared spectroscopy, and single crystal X‐ray determinations. Both 1 and 2 are structurally similar di‐nuclear complexes, which are located at crystallographic inversion centers (with the center of the central Cu₂N₂ ring). In 1 , each copper atom has a slightly distorted square pyramidal configuration, coordinated by two nitrogen atoms and one oxygen atom from L1 and another two terminal nitrogen atoms from two bridging thiocyanate anions. The Cu···Cu separation is 3.466(3) Å. The structure of 2 is similar to that of 1 , with Cu···Cu separation of 3.368(2) Å. Both 3 and 4 are linear tri‐nuclear complexes. In 3 , the central Cu²⁺ ion is located on an inversion centre and has a distorted octahedral coordination involving four bridging O atoms from two Schiff base ligands (L3) in the equatorial plane and one O atom from each bridging acetate group in the axial positions. The coordination around the terminal Cu²⁺ ions is irregular‐square pyramidal, with two O and two N atoms of L3 in the basal plane and one O atom from an acetate group in the apical position. The acetate bridges linking the central and terminal Cu²⁺ ions are mutually trans. The Cu···Cu separation is 3.009(3) Å. In 4 , the coordination configuration of the central and the terminal zinc atoms are similar to that of the 3 , with Zn···Zn separation of 3.153(4) Å. The three Schiff bases and the corresponding three copper complexes exhibit good antibacterial properties, while the zinc complex 4 has nearly no.     

Synthesis and crystal structure of aqua(diaminobithiazole) (iminodiacetato)nickel(II) hydrate

Crystals of the title compound, [(C₆H₆N₄S₂)(C₄H₅NO₄)(H₂O)Ni]·H₂O, consist of the Ni(II) complex and lattice water. The Ni(II) complex adopts a distorted octahedral coordination geometry formed by an iminodiacetate anion (IDA), a diaminobithiazole (DABT) and a coordinated water molecule. A twisted configuration of DABT is the distinguishing feature in the complex, the dihedral angle between thiazole rings of DABT being 20.04(8)°. An aromatic stacking interaction occurs between thiazole rings from neighboring complex molecules, and is considered as the reason for the twisted configuration. The tridentate IDA dianion chelates to a Ni(II) atom in afacialconfiguration. A hydrogen bond network holds the complex molecules together to form a supramolecular structure.     

Electrochemical Synthesis of MII Complexes with a Schiff Base containing an Amido Group. Crystal Structure of a Cobalt(II) Complex with a Reorganised Ligand

M(HL)(H₂O)_n complexes have been obtained by the electrochemical reaction of Fe, Co, Ni, Cu, Zn and Cd anodes with the potentially pentadentate and trianionic asymmetrical Schiff base 3‐aza‐N‐{2‐[1‐aza‐2‐(5‐nitro‐2‐hydroxylphenyl)‐vinyl]phenyl}‐4‐(5‐nitro‐2‐hydroxyphenyl)but‐3‐enamide (H₃L), containing a hard amido donor atom. The complexes have been characterized by elemental analysis, mass spectrometry, IR and ¹H NMR spectroscopies, magnetic measurements and molar conductivities. Co(HL)(H₂O) ( 2 ) has been found to rearrange in DMF solution into a crystallographically solved octahedral complex, CoL¹(H₂O)₂ ( 7 ) [where H₂L¹ is the symmetrical Schiff base ligand N,N′‐(1,2‐phenylene)‐bis(5‐nitro‐3‐hydroxysalicylidenimine)]. A hydrolysis mechanism is discussed to explain this rearrangement.     

Aquachloro[N,N′‐ethylenebis(salicylideneiminato)]manganese(III)

The title compound, aqua­chloro{2,2′‐[1,2‐ethanediyl­bis­(nitrilo­methyl­idyne)]­diphenolato‐κ⁴O,N,N′,O′}manganese(III),[MnCl(C₁₆H₁₄N₂O₂)(H₂O)], is a neutral manganese(III) complex with a pseudo‐octahedral metal centre. The equatorial plane comprises the four donor atoms of the tetradentate Schiff base ligand [Mn—O 1.886 (4) and 1.893 (4) Å, and Mn—N 1.978 (5) and 1.982 (5) Å], with a water mol­ecule [Mn—O 2.383 (4) Å] and a Cl^? ligand [Mn—Cl 2.4680 (16) Å] completing the coordination sphere. The distorted geometry is highlighted by the marked displacement of the Mn^III ion out of the least‐squares plane of the four Schiff base donor atoms by 0.165 (2) Å. These monomeric Mn^III centres are then linked into a polymeric array via hydrogen bonds between the coordinated water mol­ecule and the phenolic O‐atom donors of an adjacent Mn^III centre [O—H?O 2.789 (5) and 2.881 (5) Å].     

Two transition metal coordination polymers of the 7,7,8,8‐tetracyanoquinodimethane dianion (TCNQ2−)

Each of the two novel title transition metal coordination polymers, namely catena‐poly[[bis{[tris(2‐pyridylmethyl)amine]cobalt(II)}‐μ₄‐7,7,8,8‐tetracyanoquinodimethanide(2−)] bis[7,7,8,8‐tetracyanoquinodimethanide(1−)] methanol disolvate], {[Co₂(C₁₂H₄N₄)(C₁₈H₁₈N₄)₂](C₁₂H₄N₄)₂·2CH₃OH}_n, (I), and catena‐poly[[[[tris(2‐pyridylmethyl)amine]iron(II)]‐μ₂‐7,7,8,8‐tetracyanoquinodimethanide(2−)] methanol solvate], {[Fe(C₁₂H₄N₄)(C₁₈H₁₈N₄)]·CH₃OH}_n, (II), contains η⁴‐TPA and cis‐bridging TCNQ²⁻ ligands [TPA is tris(2‐pyridylmethyl)amine and TCNQ is 7,7,8,8‐tetracyanoquinodimethane], but the two compounds adopt entirely different structural motifs. Compound (I) consists of a ribbon coordination polymer featuring μ₄‐TCNQ²⁻ radical anion ligands bridging four different octahedral Co^II centers. Each formula unit of the polymer is flanked by two uncoordinated TCNQ⁻ anions and two methanol solvent molecules. All three TCNQ anions have crystallographic inversion symmetry. In (II), the 2₁ symmetry operator generates a one‐dimensional zigzag chain of octahedral Fe^II centers with μ₂‐TCNQ²⁻ bridges. A methanol solvent molecule forms hydrogen bonds to one of the terminal N atoms of the bridging TCNQ²⁻ dianion. To the best of our knowledge, these are the first examples of one‐dimensional coordination polymers forming from cis coordination of two TCNQ ligands to octahedral metal centers.     

Cobalt(II) and nickel(II) complexes of quinoline‐2‐carboxyl­ate

The title complexes, trans‐di­aqua­bis­(quinoline‐2‐carboxyl­ato‐κ²N,O)­cobalt(II)–water–methanol (1/2/2), [Co(C₁₀H₆NO₂)₂(H₂O)₂]·2CH₄O·2H₂O, and trans‐di­aqua­bis­(quinoline‐2‐car­box­yl­ato‐κ²N,O)­nickel(II)–water–methanol (1/2/2), [Ni(C₁₀H₆NO₂)₂(H₂O)₂]·2CH₄O·2H₂O, are isomorphous and contain Co^II and Ni^II ions at centers of inversion. Both complexes have the same distorted octahedral coordination geometry, and each metal ion is coordinated by two quinoline N atoms, two carboxyl­ate O atoms and two water O atoms. The quinoline‐2‐carboxyl­ate ligands lie in trans positions with respect to one another, forming the equatorial plane, with the two water ligands occupying the axial positions. The complex mol­ecules are linked together by hydrogen bonding involving a series of ring patterns which include the uncoordinated water and methanol mol­ecules.     

Structurally characterized homotrinuclear Salamo‐type nickel(II) complexes: Synthesis,solvent effect and fluorescence properties

Four new solvent‐induced Ni(II) complexes with chemical formulae [{NiL(μ₂‐OAc)(MeOH)}₂Ni]·2MeOH ( 1 ), [{NiL(μ₂‐OAc)}₂(n‐PrOH)(H₂O)Ni]·n‐PrOH ( 2 ), [{NiL(μ₂‐OAc)(DMF)}₂Ni] ( 3 ) and [{NiL(μ₂‐OAc)(DMSO)}₂Ni]·2DMSO ( 4 ), (H₂L = 4‐Nitro‐4′‐chloro‐2,2′‐[(1,3‐propylene)dioxybis(nitrilomethylidyne)]diphenol) have been synthesized and characterized by elemental analyses, FT‐IR, UV–Vis spectra and X‐ray crystallography. X‐ray crystal structure determinations revealed that each of the Ni(II) complexes 1–4 consists of three Ni(II) atoms, two completely deprotonated (L)^2? units, two μ₂‐acetate ions and two coordinated solvent molecules (solvents are methanol, n‐propanol, water, N,N‐dimethylformamide and dimethyl sulphoxide, respectively). Although the four complexes 1–4 were synthesized in different solvents, it is worthwhile that the Ni(II) atoms in the four complexes 1–4 adopt hexa–coordinated with slightly distorted octahedral coordination geometries, and the ratios of the ligand H₂L to Ni(II) atoms are all 2: 3. The complexes 1–4 possess self‐assembled infinite 1D, 3D, 1D and 2D supramolecular structures via the intermolecular hydrogen bonds, respectively. In addition, fluorescence behaviors were investigated in the complexes 1–4 .