Structural Studies of a Copper(II) Complex with Inequivalent 2‐Acetylpyridine 3‐Piperidylthiosemicarbazonato Ligands and a Nickel(II) Complex with Different Modes of Coordination by the Two Thiosemicarbazonato Moieties of 1‐Phenylglyoxal Bis{N(4)‐diethylthiosemicarbazone}

The crystal structure of a copper(II) complex of 2‐acetylpyridine 3‐piperidylthiosemicarbazone, [Cu(Acpip)₂], indicates a tridentate, monoanionic ligand (i. e., pyridine nitrogen, imine nitrogen and thiolato sulfur atoms) and a bidentate, monanionic ligand (i. e., imine nitrogen and thiolato sulfur atoms). The stereochemistry approaches square pyramidal with the bidentate ligand occupying an apical (imine nitrogen atom) and basal (thiolato sulfur atom) position. The structure of a nickel(II) complex of 1‐phenylglyoxal N(4)‐diethylthiosemicarbazone, [Ni(Pg4DE)], has a 4‐6‐5 trichelate system rather than the 5‐5‐5 system common to bis(thiosemicarbazones). Coordination of the hydrazinic nitrogen atom of the “phenyl arm” along with the thiolato sulfur atom provides the 4‐membered chelate ring.     

Synthesis,Crystal Structure,Antioxidation and DNA‐Binding Studies of a Zinc(II) Complex with the Bis(N‐allylbenzimidazol‐2‐ylmethyl)aniline

A complex of zinc(II) picrate (pic) with bis(N‐allylbenzimidazol‐2‐ylmethyl)aniline (abba), with composition [Zn(abba)₂](pic)₂, was synthesized and characterized by elemental analysis, electrical conductivity, IR and UV/Vis spectral measurements. The crystal structure of the zinc(II) complex has been determined by single‐crystal X‐ray diffraction. The Zn(II) is bonded to two abba ligands through four benzimidazole nitrogen, resulting in a distorted tetrahedron geometry. The DNA‐binding properties of the ligand and the zinc(II) complex were investigated by electronic absorption, fluorescence spectra and viscosity measurements. The experimental results suggest that the zinc(II) complex binds to DNA in an intercalation mode. In addition, the ligand abba and Zn(II) complex have scavenging effects for hydroxyl radicals and the complex shows stronger scavenging effects for hydroxyl radicals than the ligand.     

Zinc(II), Cadmium(II), and Mercury(II) Complexes with the 2, 2′‐Diamino‐4, 4′‐bithiazole (DABTZ) Ligand — Syntheses and X‐Ray Crystal Structure of [Hg(DABTZ)(SCN)2]

Reaction of the ligand 2, 2′‐diamino‐4, 4′‐bithiazole (DABTZ) with Zn(ClO₄)₂, CdCl₂, and Hg(SCN)₂ gives complexes with composition [Zn(DABTZ)₂](ClO₄)₂, [Cd(DABTZ)₂Cl₂], and [Hg(DABTZ)(SCN)₂]. The complexes were characterized by elemental analyses and infrared spectroscopy. The crystal structure of the [Hg(DABTZ)(SCN)₂] was determined by X‐ray crystallography. The complex is built up of a monomeric Hg(SCN)₂ unit with one 2, 2′‐diamino‐4, 4′‐bithiazole ligand coordinated to the Hg atom via the two N atoms giving rise to a five‐member chelate ring in a distorted tetrahedral environment. There is π‐π stacking interaction between the parallel aromatic rings belonging to adjacent chain as planar species in which the mean molecular planes are close to parallel and separated by a distance of ～ 3.5Å, close to that of the planes in graphite. The coordinated 2, 2′‐diamino‐4, 4′‐bithiazole molecule is involved in hydrogen bonding acting as hydrogen‐bond donors with N atoms from the SCN ligand as potential hydrogen‐bond acceptors. The hydrogen bonding yields infinite chains parallel to the crystallographic vectors a and b. Each molecule is bonded to three neighbours. Both amine H atoms are hydrogen bonded to N atoms.     

Structural Study of Nickel(II), Copper(II), and Palladium(II) Complexes of 2‐Pyridineformamide 3‐Hexamethyleneiminylthiosemicarbazone

Reduction of 2‐cyanopyridine by sodium in the presence of 3‐hexamethyleneiminylthiosemicarbazide produces 2‐pyridineformamide 3‐hexamethyleneiminylthiosemicarbazone, HAmhexim. Complexes with nickel(II), copper(II) and palladium(II) have been prepared and the following complexes structurally characterized: [Ni(Amhexim)OAc], [{Cu(Amhexim)}₂C₄H₄O₄]·2DMSO·H₂O, [Cu(HAmhexim)Cl₂] and [Pd(Amhexim)Cl]. Coordination is via the pyridyl nitrogen, imine nitrogen and thiolato or thione sulfur atom when coordinating as the anionic or neutral ligand, respectively. [{Cu(Amhexim)}₂C₄H₄O₄] is a binuclear complex with the two copper(II) ions bridged by the succinato group in [Cu‐(HAmhexim)Cl₂] the Cu atom is 5‐coordinate and close to a square pyramid structure and in [Ni(Amhexim)OAc] and [Pd(Amhexim)Cl] the metal atoms are planar, 4‐coordinate.     

A Novel Proton Transfer Compound Containing 2, 6‐Pyridinedicarboxylic Acid and Creatinine and its Zinc(II) Complex — Synthesis,Characterization, Crystal Structure,and Solution Studies

The 1:1 proton transfer compound LH₂, (creatH)⁺ (pydcH)^?, has been prepared from the reaction of creatinine, creat, and dipicolinic acid, pydcH₂, (2, 6‐ pyridinedicarboxylic acid) and characterized using IR, ¹H and ¹³C NMR spectroscopy. The first coordination complex (creatH)[Zn(pydc)(pydcH)]·4H₂O, was prepared using LH₂ and zinc(II) nitrate, and characterized using IR, ¹H and ¹³C NMR spectroscopy and single crystal X‐ray crystallography. The crystal system is triclinic with space group with two molecules per unit cell. The unit cell dimensions are a = 8.085(2) Å, b = 10.802(4) Å, c = 13.632(4) Å, α = 104.98(2)°, β = 90.31(2)° and γ = 92.55(3)°. The structure has been refined to a final value for the crystallographic R factor of 0.0381 based on 3003 reflections. The zinc atom is six‐coordinated with a distorted octahedral geometry. The (pydc)^2? and (pydcH)^? units are almost perpendicular to each other. Extensive hydrogen bondings between carboxylate groups, (creatH)⁺ and water molecules throughout the zinc(II) complex as well as π–π stacking and ion pairing play important roles in stabilizing the corresponding lattices. The protonation constants of the building blocks of the pydcH₂‐creat adduct, the equilibrium constants for the reaction of (pydc)^2? with creat and the stoichiometry and stability of the Zn^II complex with LH₂ in aqueous solution were accomplished by potentiometric pH titration. The solution studies support a self‐associated (creatH)⁺(pydcH)^? as the most abundant species at pH = 3.4. The stoichiometry of the crystalline complex (i.e. (creatH) [Zn(pydc)(pydcH)])and that of the most abundant species detected in solution were found the same.     

Synthesis,Spectroscopic and Structural Aspects of Mono‐ and Diorganothallium(III) Complexes of 2, 6‐Diacetylpyridine Bis(thiosemicarbazone) (H2DAPTSC) — A New Coordination Mode of the HDAPTSC— Anion

The reaction of 2, 6‐diacetylpyridine bis(thiosemicarbazone) (H₂DAPTSC) with dimethylthallium hydroxide yielded the complexes [(TlMe₂)₂(DAPTSC)] and [TlMe₂(HDAPTSC)]. The structure of [TlMe₂(HDAPTSC)], determined by X‐ray diffractometry, exhibits a hitherto unknown coordination mode of the HDAPTSC^— anion in which its deprotonated thiosemicarbazone chain coordinates one metal atom through its sulphur and hydrazinic N atoms while a second metal atom is weakly coordinated through the S atom of the undeprotonated thiosemicarbazone chain. Each thallium atom is coordinated in both ways, with the result that the [TlMe₂(HDAPTSC)] units are linked in infinite helical chains in the direction of the b axis. When reacting with diphenylthallium(III) hydroxide, H₂DAPTSC induced a dephenylation process which led to the monophenylthallium(III) complex [TlPh(DAPTSC)]. Recrystallization from acetone yielded crystals of [TlPh(DAPTSC)]·C₃H₆O in which X‐ray diffractometry showed DAPTSC^2— to be pentadentate, coordinating through its sulphur, azomethine N and pyridine N atoms. The ¹H, ¹³C and ²⁰⁵Tl NMR data of [TlPh(DAPTSC)] indicate that its solid state molecular structure persists in DMSO solution, while those of [TlMe₂(HDAPTSC)] indicate rapid alternation between coordination of the metal atom to one of the HDAPTSC^— thiosemicarbazone chains and its coordination to the other.     

Synthesis,Characterization and Crystal Structure of Dimeric {[(AMTTO)2Ag]NO3}2 (AMTTO = 4‐Amino‐6‐methyl‐1, 2, 4‐triazine‐3(2H)‐thione‐5‐one)

The reaction of 4‐Amino‐6‐methyl‐1, 2, 4‐triazine‐3(2H)‐thione‐5‐one (AMTTO, 1 ) with silver nitrate in methanol led to the dimeric complex {[(AMTTO)₂Ag]NO₃}₂ ( 2 ). 2 was characterized by elemental analyses and IR spectroscopy as well as by X‐ray structure analysis. Crystal data for 2 at ?80 °C: crystal system orthorhombic, space group P2₁2₁2₁ with a = 1043.6(1), b = 1329.6(1), c = 2358.4(1) pm, Z = 8 and R₁ = 0.037. The cation possesses a highly distorted linear coordination sphere in the solid state.     

EPR Spectroscopy of 4, 4′‐Bis(tert‐butyl)‐2, 2′‐bipyridine‐1, 2‐dithiolatocuprates(II) in Host Lattices with Different Coordination Geometries

A series of new heteroleptic MN₂S₂ transition metal complexes with M = Cu²⁺ for EPR measurements and as diamagnetic hosts Ni²⁺, Zn²⁺, and Pd²⁺ were synthesized and characterized. The ligands are N₂ = 4, 4′‐bis(tert‐butyl)‐2, 2′‐bipyridine (tBu₂bpy) and S₂ =1, 2‐dithiooxalate, (dto), 1, 2‐dithiosquarate, (dtsq), maleonitrile‐1, 2‐dithiolate, or 1, 2‐dicyanoethene‐1, 2‐dithiolate, (mnt). The Cu^II complexes were studied by EPR in solution and as powders, diamagnetically diluted in the isostructural planar [Ni^II(tBu₂bpy)(S₂)] or[Pd^II(tBu₂bpy)(S₂)] as well as in tetrahedrally coordinated[Zn^II(tBu₂bpy)(S₂)] host structures to put steric stress on the coordination geometry of the central CuN₂S₂ unit. The spin density contributions for different geometries calculated from experimental parameters are compared with the electronic situation in the frontier orbital, namely in the semi‐occupied molecular orbital (SOMO) of the copper complex, derived from quantum chemical calculations on different levels (EHT and DFT). One of the hosts, [Ni^II(tBu₂bpy)(mnt)], is characterized by X‐ray structure analysis to prove the coordination geometry. The complex crystallizes in a square‐planar coordination mode in the monoclinic space group P2₁/a with Z = 4 and the unit cell parameters a = 10.4508(10) Å, b = 18.266(2) Å, c = 12.6566(12) Å, β = 112.095(7)°. Oxidation and reductions potentials of one of the host complexes, [Ni(tBu₂bpy)(mnt)], were obtained by cyclovoltammetric measurements.     

Synthesis,characterization and antimicrobial activity of a Zn(II) complex with 1-(1H-benzoimidazol-2-yl)-ethanone thiosemicarbazone

A new Zn(II) complex with 1-(1H-benzoimidazol-2-yl)-ethanone thiosemicarbazone [Zn(NO₃)(H₂O)(C₁₀H₁₁N₅S)]NO₃ was prepared and characterized by elemental analyses, FT-IR, ¹H NMR spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and single-crystal X-ray diffraction analysis. The coordination geometry of the pentacoordinated zinc is a distorted square pyramid. The antimicrobial activity of the complex was evaluated using a broth micro-dilution method against a panel of human pathogenic Gram positive, Gram negative bacteria and the yeast Candida albicans. The best inhibitory effect was observed against Enterobacter aerogenes (MIC = 0.031 mg mL^?1).     

Pseudohalide‐directed Assembly of Two Zinc(II) Coordination Polymers with a 3,4‐Bis(3‐pyridyl)‐5‐(4‐pyridyl)‐1,2,4‐triazole Tecton

The zinc(II) pseudohalide complexes {[Zn(L³³⁴)(SCN)₂(H₂O)](H₂O)₂}_n ( 1 ) and [Zn(L³³⁴)(dca)₂]_n ( 2 ) were synthesized and characterized using the ligand 3,4‐bis(3‐pyridyl)‐5‐(4‐pyridyl)‐1,2,4‐triazole (L³³⁴) and ZnCl₂ in presence of thiocyanate (SCN^–) and dicynamide [dca, N(CN)₂^–] respectively. Single‐crystal X‐ray structural analysis revealed that the central Zn^II atoms in both complexes have similar octahedral arrangement. Compound 1 has a 2D sheet structure bridged by bidentate L³³⁴ and double μ_N,S‐thiocyanate anions, whereas complex 2 , incorporating with two monodentate dicynamide anions, displays a two‐dimensional coordination framework bridged by tetradentate L³³⁴ ligand. Structural analysis demonstrated that the influence of pseudohalide anions plays an important role in determining the resultant structure. Both complexes were characterized by IR spectroscopy, microanalysis, and powder X‐ray diffraction techniques. In addition, the solid fluorescence and thermal stability properties of both complexes were investigated.     

Structure and Thermal Stability of a Novel 2‐D Layered Copper(II) Coordination Polymer with the Bidentate Ligand 1, 2, 4‐Triazol‐5‐one

Single crystals of {[Cu(TO)₂(H₂O)₂](NO₃)₂}_n (TO: 1, 2, 4‐triazol‐5‐one) were grown by slow evaporation from aqueous solution. It crystallizes in the orthorhombic space group Pbca, with a = 7.082(1), b = 10.285(1), c = 17.911(3)Å, V = 1304.6(3)ų, Z = 4. The Cu^II distorted octahedra are bridged by bidentate TO ligands into infinite 2‐D interlaced rhombic grid‐like network planes, {[Cu(TO)₂(H₂O)₂]²⁺}_n. Hydrogen bonds, electrostatic interactions, and weak van der Waals' forces assemble these planes and the NO₃^— anions to a layered structure. The title compound decomposes at 153.4 °C to the final products, Cu(CN)₂ and CuO.     

Substituted 2,2′‐Bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl Complexes of Zinc

The condensation reaction of 2,2′‐diamino‐4,4′‐dimethyl‐6,6'‐dibromo‐1,1′‐biphenyl with 2‐hydroxybenzaldehyde as well as 5‐methoxy‐, 4‐methoxy‐, and 3‐methoxy‐2‐hydroxybenzaldehyde yields 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyl ( 1a ) as well as the 5‐, 4‐, and 3‐methoxy‐substituted derivatives 1b , 1c , and 1d , respectively. Deprotonation of substituted 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls with diethylzinc yields the corresponding substituted zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls ( 2 ) or zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyls ( 3 ). Recrystallization from a mixture of CH₂Cl₂ and methanol can lead to the formation of methanol adducts. The methanol ligands can either bind as Lewis base to the central zinc atom or as Lewis acid via a weak O–H ··· O hydrogen bridge to a phenoxide moiety. Methanol‐free complexes precipitate as dimers with central Zn₂O₂ rings.     

Synthesis,Crystal Structure,and Photocatalytic Properties of a Zinc(II) Coordination Polymer Based on 3‐Hydroxy‐2‐pyridinecarboxylic Acid

The zinc(II) compound, [Zn₃(HL)₆]_n ( 1 ) (H₂L = 3‐hydroxypyridine‐2‐carboxylic acid) was synthesized by a solvothermal reaction of Zn(NO₃)₂ · 6H₂O and 3‐hydroxypyridine‐2‐carboxylic acid as raw materials. The structure of complex 1 was determined by single‐crystal X‐ray diffraction analysis and further characterized by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, as well as powder X‐ray diffraction. X‐ray structure analysis demonstrates that the complex crystallizes in the monoclinic system, space group P2₁/n. There are three zinc ions in the asymmetric unit, which are either five‐coordinate or six‐coordinate. The asymmetric units are further bridged by the carboxylate of the organic ligands, featuring a 2D framework. The solid state diffuse‐reflectance UV/Vis spectra reveals that complex 1 has semiconducting nature with the energy bandgap (E_g) estimated to be 3.11 eV. The photocatalytic properties of complex 1 in degradation of organic dyes were further investigated. Results showed that the complex could degrade 54 % of the dye methylene blue solution within 120 min under UV irradiation light and reused for five times without the decline of the photocatalytic activity.     

Syntheses,Crystal Structures,and Photoluminescence of Zinc(II) and Cobalt(II) Coordination Polymers Based on Semiflexible 1,4‐Bis(4‐phenoxy)benzenedicarboxylate

Hydrothermal reactions of Co(NO₃)₂ · 6H₂O and Zn(NO₃)₂ · 6H₂O with 1,4‐bis(4‐phenoxy)benzenedicarboxylic acid (H₂bcpb) resulted in the formation of the coordination polymers [Zn(bcpb)(Py)]_n ( 1 ), and [Co(bcpb)(Py)₂]_n ( 2 ), respectively. Their structures were studied by single‐crystal and powder X‐ray diffraction methods and further characterized by IR spectroscopy, elemental analyses, and thermogravimetric analyses (TGA). Single X‐ray diffraction analyses revealed that complex 1 has a 1D loop chain. Each repeated unit contains two carboxylate ligands and two SBUs (secondary building units), whereas complex 2 has a 2D 4‐connected sql sheet with point symbol (4⁴.6²). The complexes are further expanded to 3D supramolecular structures through non‐covalent bonding interactions. Besides, photoluminescent property of complex 1 was also investigated in the solid state at room temperature.     

Synthesis,Structure, Antibacterial and Spectroscopic Properties of a Zinc(II) Complex with the Ligand 4‐Heptanoyl‐pyrazol‐5‐one

The long‐chain ligand, 1‐phenyl‐3‐methyl‐4‐heptanoyl‐pyrazol‐5‐one (HL) and its zinc(II) complex ZnL₂ were synthesized. The structure and the properties of ZnL₂ were characterized by elemental analysis, IR spectroscopy, X‐ray diffraction, and thermogravimetric analysis. The zinc ion is five‐coordinated in a square‐pyramidal environment by four oxygen atoms of the HL ligands in the equatorial plane and one water molecule in the axial position. The water molecule is directly bonded to Zn²⁺ and involved in intermolecular hydrogen bonding network. The complex and its corresponding ligand were screened in vitro against some strains of the human pathogenic bacteria. The metal complex exhibits higher antibacterial activity than its corresponding ligand. The complex exhibits purple effect emission as the result of fluorescence from the intraligand emission excited state.     

Two Coordination Polymers based on 2‐Ethyl‐1H‐imidazole‐4,5‐dicarboxylic Acid and 1,3‐Bis(4‐pyridyl)propane: Synthesis,Crystal Structures,and Photoluminescent Properties

Two coordination polymers, [Cd(Heidc)(bpp)]_n ( 1 ) and [Zn₃ (eidc)₂(bpp)(H₂O)₂] · 2H₂O}_n ( 2 ) (H₃eidc = 2‐ethyl‐4,5‐imidazole dicarboxylic acid, bpp = 1,3‐bis(4‐pyridyl)propane) were hydrothermally synthesized and characterized by elemental analysis, IR, spectroscopy single‐crystal X‐ray diffraction, and thermogravimetric analyses. Compound 1 features a 2D layer formed by C–H ··· π stacking interactions between adjacent chains, whereas compound 2 shows a 3D (8³)₂(8⁵.10)‐tfc framework constructed of the 2D (6,3) layer. The result demonstrates that the central metal atoms play a key role in governing the coordination motifs. Moreover, solid‐state properties such as thermal stabilities and photoluminescence of 1 and 2 were also investigated.     

Crystal Structures and Solution Studies of Two Novel Zinc(II) Complexes of a Proton Transfer Compound Obtained from 2, 6‐Pyridinedicarboxylic Acid and 1, 10‐Phenanthroline: Observation of Strong Intermolecular Hydrogen Bonds

The proton transfer compound LH₂ , (phenH⁺)₂(pydc^2—), has been prepared from 1, 10‐phenanthroline, phen, and 2, 6‐pyridinedicarboxylic acid, (dipicolinic acid), pydcH₂. Characterization was performed using solution and solid phase CP/MAS ¹³C NMR and IR spectroscopy. The reactions of this adduct with ZnSO₄·7H₂O and Zn(NO₃)₂·4H₂O give the complexes, [Zn(pydc)₂][Zn(phen)₂(H₂O)₂]·7H₂O (1) and [Zn(phen)₃]₄(H(Hpydc)₂)(NO₃)₇·26H₂O (2) , respectively. These complexes were characterized by ¹H and ¹³C NMR spectroscopy and single crystal X‐ray analysis. The complexes crystallize in the triclinic space group P1 with Z = 2. The unit cell dimensions for complex 1 and 2 are: a = 9.9838(9) Å, b = 14.7483(13) Å, c = 14.8365(13) Å and a = 12.640(4) Å, b = 15.855(5) Å, c = 21.830(7) Å, respectively. In complex 1 (pydc^2—) and phen, are tri‐ and bidentate ligands, respectively, and an anionic [Zn(pydc)₂]^2— and cationic [Zn(phen)₂(H₂O)₂]²⁺ complex are formed simultaneously. In complex 2 , three phen participate in complexation leaving hydrogen‐bis(pyridine‐2‐carboxylate), (H(Hpydc)₂)^— as a supramolecular anion. The fragments (H(Hpydc)₂)^—, 7 NO₃^—, and 26 H₂O in complex 2 are joined together by extensive and strong H‐bonding; therefore, the structure is composed of [Zn(phen)₃]₄⁸⁺, and an anionic hydrogen bond supramolecular assembly with the formula, {(H(Hpydc)₂(NO₃)₇)^8— · 26H₂O}_n. The anionic species (H(Hpydc)₂)^— has a special position at the inversion center, as well as one of the NO₃^— anions, which is disordered over the inversion center. Most of the hydrogen bonds in complex 2 represent strong H‐bonding. The protonation constants of the building blocks of the pydc‐phen adduct, the equilibrium constants for the reaction of (pydc^2—) with phenanthroline and the stoichiometry and stability of the Zn^II complex with LH₂ on aqueous solution were determined by potentiometric pH titration. The solution study results support self‐association between (pydc^2—) and (phenH⁺) with a stoichiometry for the Zn(II) complex similar to that observed for the isolated crystalline complex.     

Syntheses and Characterization of Zinc,Cadmium, and Mercury(II) Complexes with N‐(2‐pyridyl)carbonylaniline (L), X‐ray Crystal Structure of [Hg(L)(SCN)2]

The reaction of N‐(2‐pyridyl)carbonylaniline (L) with Zn(NO₃)₂, CdCl₂, and Hg(SCN)₂ gives the following complexes: [Zn(L)₂](NO₃)₂, [Cd(L)₂Cl₂], and [Hg(L)(SCN)₂]. The new complexes were characterized by elemental analyses and IR‐, ¹H‐, ¹³C‐NMR spectroscopy. The crystal structure of the [Hg(L)(SCN)₂] was determined by single crystal X‐ray analysis. The monomeric complex is built up of a Hg(SCN)₂ unit with one N‐(2‐pyridyl)carbonylaniline (L) ligand coordinated to the Hg atom via the ring pyridinic nitrogen atom and the carbonyl oxygen atom forming a five‐membered chelate ring. The Hg atom has a distorted tetrahedral environment. There is π‐π stacking interaction between the parallel aromatic rings belonging to adjacent chain as planar species in which the mean molecular planes are close to parallel and separated by a distance of ～ 3.5Å, close to that of the planes in graphite. The coordinated N‐(2‐pyridyl)carbonylaniline (L) molecule is involved in hydrogen bonding acting as hydrogen‐bond donors with S and N atoms from SCN^— ligand as potential hydrogen‐bond acceptors. There is a shortest intermolecular contacts between the S and N atoms. The hydrogen bonding and shortest intermolecular contacts between the S and N atoms yields infinite chains parallel to the crystallographic vector c. Each molecule is bonded to two neighbors.     

Synthesis,Crystal Structure and Spectroscopic Properties of Bis(1‐(E)‐2‐formylpyridine semicarbazone)nickel(II) Diperchlorate Monohydrate

Pale‐green crystals of the title complex were prepared by reaction of 2‐formylpyridine semicarbazone (HCSpy) and nickel(II) perchlorate in boiling ethanol. The crystals are triclinic with the nickel ion in an octahedral arrangement, coordinated by two nitrogen atoms and one oxygen donor atom from each ligand molecule. The effect of coordination on bond lengths and angles was explored by comparison with the single‐crystal structure data of the free ligand HSCpy, which was collected as well. The assumed coordination mode was supported by ¹H and ¹³C NMR spectroscopic data. A detailed analysis of the electronic properties, including semi‐empirical quantummechanical calculations is presented. Furthermore, the data obtained from magnetic susceptibility and EPR measurements are in accordance with a low‐spin d⁸ nickel(II) complex.     

Synthesis,Structure, and Magnetic Characterization of a Series of Iron(II) Coordination Frameworks with 2, 6‐Bis(1, 2,4‐triazole‐4‐yl)pyridine

Based on the bis‐triazole ligand 2, 6‐bis(1, 2,4‐triazole‐4‐yl)pyridine (L), the triazole‐iron(II) complexes [Fe(L)₂(dca)₂(H₂O)₂] · 2H₂O ( 1 ) (Nadca = sodium dicyanamide), {[Fe(μ₂‐L)₂(H₂O)₂]Cl₂}_n ( 2 ), and {[Fe(μ₂‐L)₂(H₂O)₂](ClO₄)₂ · L · H₂O}_n ( 3 ) were isolated by solvent diffusion methods. When iron(II) salts and Nadca were used, compound 1 was isolated, which contains mononuclear Fe(L)₂(dca)₂(H₂O)₂ units. When FeCl₂ or FeClO₄ were used, one‐dimensional (1D) cation iron(II) chains ( 2 ) and two‐dimensional (2D) cation iron(II) networks ( 3 ) were isolated indicating anion directing structural diversity. Moreover, variable‐temperature magnetic susceptibility data of 1 – 3 were recorded in the temperature range 2–300 K. The magnetic curve of complex 2 was fitted by using the classical spin Heisenberg chain model indicating anti‐ferromagnetic interactions (J = –5.31 cm^–1). Obviously complexes 1 – 3 show no detectable thermal spin crossover behaviors, the lack of spin‐crossover behavior may be correlated with FeN₄O₂ coordination spheres in 1 – 3 .