Syntheses,structures, and properties of two 2-D Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and polycarboxylate ligands

Two 2-D Cd(II) complexes, {[Cd(imb)(bdc)(H₂O)]·CH₃OH}_n (1) and {[Cd(imb)(Hbtc)(CH₃OH)]·2H₂O·CH₃OH}_n (2), have been synthesized by reactions of CdCl₂·2.5H₂O with 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,3-benzenedicarboxylic acid (H₂bdc) or 1,3,5-benzenetricarboxylic acid (H₃btc). Single-crystal X-ray diffraction shows that 1 possesses an infinite 2-D layered structure in which all the carboxylates chelate Cd(II) and imb bridge Cd(II) ions. Complex 2 also features an infinite 2-D layered structure and imb ligands also bridge Cd(II) ions, but two carboxylates of each 1,3,5-benzenetricarboxylate coordinate to Cd(II) in monodentate or chelating mode, leaving the third one, which is not deprotonated, uncoordinated. IR spectra, fluorescent properties, and thermogravimetric analyses of both complexes have been investigated.     

Syntheses,structural characterization,and properties of Mn(II) and Cd(II) complexes from 5-[4-(1H-imidazol-1-Yl)phenyl]-1H-tetrazole

Reactions of Mn(II) and Cd(II) salts with 5-(4-(1H-imidazol-1-yl)phenyl)-1H-tetrazole (HL) under hydrothermal conditions result in complexes [Mn(L)₂(H₂O)₄] · 2H₂O (I) and [Cd(L)₂(H₂O)₂] (II), which have been characterized by single crystal and powder X-ray diffractions (CIF files CCDC nos. 943861 (I), 943862 (II)), IR spectroscopy, element and thermogravimetric analyses. Two complexes exhibit structural diversity dependent on different metal salts. Complex I shows discrete mononuclear structure, which can be further linked to build a 3D supramolecular framework through hydrogen bonding interactions. Complex II displays 1D zigzag-chain structure, and an extended 3D framework can be formed by hydrogen bonding. Interestingly, tetranuclear water clusters were generated in I, which can be linked by Mn²⁺ ions to show 1D metal-bridged water cluster-chain structure. The present work provides an example that metal centers impact on coordination modes of ligand and consequent structural variation of resulted complexes. Moreover, fluorescence property of II was investigated.

     

Construction of Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and 1,4-benzenedicarboxylate

Three new Cd(II) complexes incorporating both 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,4-benzenedicarboxylate (bdic^2?), [CdCl(bdic)_1/2(imb)₂]_n (1), {[Cd(bdic)(imb)(H₂O)]·DMF·2H₂O}_n (2), and [Cd(bdic)(imb)]·3H₂O}_n (3), have been prepared and structurally characterized by single crystal X-ray diffraction. Bdic^2? anions connect the?Cd-imb-Cd-imb?chains leading to a 2-D structure of 1. Bdic^2?(A) and bdic^2?(B) anions link the binuclear [Cd₂(imb)₂(H₂O)₂] units forming a 2-D structure of 2. Complex 3 features a 2-D structure involving supramolecular “double-layer” motifs. IR spectra and thermogravimetric curves are consistent with the results of the X-ray crystal structure analysis; 1–3 exhibit good fluorescence in the solid state at room temperature.     

Syntheses,crystal structures,and fluorescent properties of two 2-D Cd(II) complexes based on 2-((1H-1,2,4-triazol-1-yl)methyl)-1H-benzimidazole and 1,2,4,5-benzenetetracarboxylate

Two complexes formulated as {[Cd(btec)_0.5(tmb)H₂O]·4H₂O}_n (1) and {[Cd(H₂btec)(tmb)(H₂O)]·2H₂O}_n (2) (H₄btec?=?1,2,4,5-benzenetetracarboxylic acid, tmb?=?2-((1H-1,2,4-triazol-1-yl)methyl)-1H-benzimidazole) have been synthesized and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Single crystal X-ray diffraction shows that 1 has a 2-D layer structure in which tmb bridges and all of the carboxylates from 1,2,4,5-benzenetetracarboxylate chelate. In 2 Cd(II) ions are bridged by monodentate carboxylates leading to a 2-D layer structure with all tmb ligands coordinated monodentate to Cd(II), hanging at two sides of the layers. Complexes 1 and 2 are further extended to 3-D supramolecular structures by hydrogen bonding interactions. Luminescent properties have been investigated in the solid state at room temperature.     

Synthesis,structures and thermal stabilities of three 1-D coordination polymers based on flexible polycarboxylates

Three new coordination polymers, [Cu(butca)_0.5(bipy)(H₂O)] _n · 2nH₂O (1), [Zn(H₂butca) (phen)(H₂O)] _n · nH₂O (2), and [Cd(H₂chhca)_0.5(phen)(H₂O)] _n · 2nH₂O (3) (H₄butca =1,2,3,4-butanetetracarboxylic acid, H₆chhca = 1,2,3,4,5,6-cyclohexanehexacarboxylic acid), were prepared and characterized by EA, IR, TG, and X-ray crystallography. Complex 1 is a 1-D double-chain coordination polymer in which tetradentate butca^4? coordinates to four Cu(II) ions through four monodentate carboxylates. Complex 2 is a 1-D chain with tridentate H₂butca^2? coordinating to two Zn(II) ions through monodentate and chelating carboxylates. Complex 3 is a 1-D double-chain coordination polymer. H₂chhca^4? is octadentate coordinating to four Cd(II) ions through four chelating carboxylates. Hydrogen bonds and π–π stacking interactions play important roles in the formation of supramolecular architectures. The thermal stabilities of 1–3 show dehydrated coordination polymers are thermally stable in the range 260–400°C.     

Dinuclear copper(II) complex and 1-D copper(II) complex with taurine Schiff base: synthesis,crystal structure,and properties

A dinuclear copper(II) compound, [Cu(btssb)(H₂O)]₂ · 4(H₂O) (1), and a 1-D chain copper(II) compound, [Cu(ctssb)(H₂O)] _n (2) [where H₂btssb is 2-[(5-bromo-2-hydroxy-benzylidene)-amino]-ethanesulfonic acid and H₂ctssb is 2-[(3,5-dichloro-2-hydroxy-benzylidene)-amino]-ethanesulfonic acid], were prepared and characterized. Compound 1 crystallizes in the monoclinic space group P2₁/c, with a = 10.109(2) Å, b = 20.473(4) Å, c = 6.803(1) Å, β = 100.32(3)°, V = 1385.1(5) ų, and Z = 2; R ₁ for 1796 observed reflections [I > 2σ(I)] was 0.0357. The geometry around each copper(II) can be described as slightly distorted square pyramidal. The Cu^II ··· Cu^II distance is 5.471(1) Å. Compound 1 formed a 1-D network through O–H ··· O hydrogen bonds and 1-D water chains exist. The 1-D chain complex 2 crystallizes in the triclinic space group P 1, with a = 5.030(2) Å, b = 7.725(2) Å, c = 17.011(5) Å, α = 92.706(4)°, β = 97.131(4)°, γ = 102.452(3)°, V = 638.6(3) ų, and Z = 2; R ₁ for 1897 observed reflections [I > 2σ(I)] was 0.0171. In 2, Cu(II) was also a slightly distorted square pyramid formed by two oxygens and one nitrogen from ctssb, one oxygen from another ctssb, and one water molecule. The complex formed a 1-D chain through O–S–O bridge of ctssb ligand. The 1-D chain further constructed a double chain through O?H ··· O hydrogen bonds.     

Syntheses,crystal structures,and fluorescent properties of 2-D Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and 1,2,4,5-benzenetetracarboxylate ligands

Two new complexes, {[Cd(btec)_0.5(imb)(CH₃OH)]·CH₃OH}_n (1) and {[Cd(btec)_0.5(H₂btec)]·(H₂imb)·2H₂O}_n (2) (H₄btec = 1,2,4,5-benzenetetracarboxylic acid, imb = 2-(1H-imidazol-1-methyl)-1H-benzimidazole), have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. Both complexes exhibit 2-D network structures. In 1, each 1,2,4,5-benzenetetracarboxylate links four Cd²⁺ cations, and each Cd²⁺ cation connects two 1,2,4,5-benzenetetracarboxylates, to form a 2-D layer, with the imb ligands located on each side of the 2-D layer. In 2, there are two kinds of 1,2,4,5-benzenetetracarboxylates in the structure. One kind is completely deprotonated and acts as hexadentate linkers, leading to a 2-D layer. The other kind is only doubly deprotonated and decorates each side of the 2-D layer. In 2, imb is protonated, forming (H₂imb)²⁺ cations that only cocrystallize with the negatively charged Cd coordination polymer ({[Cd(btec)_0.5(H₂btec)]^2?}_n), but does not coordinate to the Cd²⁺ cations. IR spectra, PXRD patterns, thermogravimetric analyses, and fluorescent properties of 1 and 2 have also been determined.     

Synthesis,properties, and X-ray crystal structures of two Ag(I) complexes with 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid

Two 1-D and 3-D Ag(I) complexes involving 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid (H₃PIDC) have been characterized by infrared spectrum, elemental analysis, and single-crystal X-ray diffraction. [Ag₂(HPIDC)]_n (1), synthesized under hydrothermal conditions, gave a 3-D framework; [Ag₂(HPIDC)(MBI)]_n (2) (MBI?=?2-methyl-1H-benzo[d]imidazole), with MBI as the second ligand, gave a 1-D zigzag chain and further formed a 3-D supramolecular structure through π···π interactions. The most interesting structural features of these complexes are the presence of C–H···Ag hydrogen bonding interactions and Ag···C weak interactions between the Ag centers and H₃PIDC. Luminescence indicates that 2 has significantly stronger fluorescent emissions than 1 in the solid state at room temperature.     

Self-assembly of 1-D, 2-D,and 3-D transition-metal coordination polymers based on a T-shaped tripodal ligand 4-(4,5-dicarboxy-1H-imidazol-2-yl)pyridine 1-oxide

Three coordination polymers, {[Co(C₁₀H₅N₃O₅)(H₂O)₂]·H₂O}_n (1), {[Mn₃(C₁₀H₅N₃O₅)₂Cl₂(H₂O)₆]·2H₂O}_n (2), and {[Cu₃(C₁₀H₄N₃O₅)₂(H₂O)₃]·4H₂O}_n (3), based on a T-shaped tripodal ligand 4-(4,5-dicarboxy-1H-imidazol-2-yl)pyridine 1-oxide (H₃DCImPyO), were synthesized under hydrothermal conditions. The polymers showed diverse coordination modes, being characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray structure analysis. In 1, the HDCImPyO^2? generated a 1-D chain by adopting a μ₂-kN, O : kN′, O′ coordination mode to bridge two Co(II) ions in two bis-N,O-chelating modes. In 2, the HDCImPyO^2? adopted a μ₃-kN, O : kO′, O′′ : O′′′ coordination mode to bridge two crystallographically independent Mn(II) ions, forming a 2-D hcb network with {6³} topology. In 3, by adopting μ₄-kN, O : kO′, O′′ : kN′′, O′′′ : O′′′′ coordination, DCImPyO^3? bridged three crystallographically independent Cu(II) ions to form a 3-D framework having the stb topology.     

Three new binuclear copper(II) complexes with isonicotinic acid N-oxide: syntheses,crystal structures and properties

Three new copper(II) complexes with isonicotinic acid N-oxide (HL) and 1,10-phenanthroline (phen) as ligands, [Cu(L)(phen)(H₂O)]₂(NO₃)₂···2H₂O (1), [Cu(L)(phen)(H₂O)]₂(ClO₄)₂···2H₂O (2), and [Cu(L)(phen)Br]₂- [Cu(L)(phen)(H₂O)]₂Br₂···6H₂O (3) have been synthesized and structurally characterized. The structures of all three complexes feature a Cu₂ dimer formed by two Cu(II) ions interconnected by two bridging ligands. Each copper(II) ion has a distorted square pyramidal coordination geometry with elongated axial coordination by an aqua ligand or halogen anion. The isonicotinic acid N-oxide anion is bidentate, being coordinated to two Cu(II) ions through its N-O oxygen and one of its carboxylate oxygen atoms. Magnetic susceptibility measurements show a Curie–Weiss paramagnetic behavior characteristic of one unpaired electron for a copper(II) ion for all three complexes.     

Synthesis,spectra, crystal structure and thermal properties of a polymeric 1-D cobalt(II) cyanato complex with hexamethylenetetramine

A new cobalt(II) cyanato complex, [Co(NCO)₂(H₂O)₂(hmt)] (I) where hmt is hexamethylenetetramine, has been synthesized and structurally characterized. The electronic spectra of the solid compound suggest octahedral cobalt and IR spectra revealed monodentate N-cyanato groups and aqua ligands, while hmt is a bridging N, N′-bidentate leading to a 1-D infinite polymeric chain. The structure has been confirmed from single crystal X-ray diffraction. Crystal data for I : Fw 319.20, a = 9.234(2), b = 11.252(2), c = 12.576(3) Å, β = 107.75(3)°, V = 1244.5(4) ų, Z = 4, T = 100 K. Crystal system : monoclinic, space group : C2/c. Hydrogen bonds of the type O–H ··· O and O–H ··· N between aqua molecules and O atom of the terminal N-cyanato groups or an N atom of hmt ligands consolidate and extend the structure to a 3-D network. The thermal properties of I are reported.     

Cd(II) and Cu(II) coordination polymers based on a multidentate N-donor ligand: syntheses,crystal structures,optical band gaps,and photoluminescence

Four Cd(II)- and Cu(II)-containing coordination polymers (CPs) based on a multidentate N-donor ligand and varied dicarboxylate anions, [Cd(3,3′-tmbpt)(p-bdc)]·2.5H₂O (1), [Cd(3,3′-tmbpt)(m-bdc)]·2H₂O (2), [Cu(3,3′-tmbpt)(m-bdc)]·H₂O (3), and [Cu(3,3′-tmbpt)(p-bdc)]·2H₂O (4), where 3,3′-tmbpt = 1 ? ((1H-1,2,4-triazol-1-yl)methyl)-3,5-bis(3-pyridyl)-1,2,4-triazole, p-H₂bdc = 1,4-benzenedicarboxylic acid, and m-H₂bdc = 1,3-benzenedicarboxylic acid, have been prepared hydrothermally. The structures of the compounds were determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra and elemental analyses. Compound 1 exhibits a 3-D twofold interpenetrating framework with a 6⁵·8 CdSO₄ topology. Compound 2 is a 2-D layer containing meso-helical chains with a 4⁴·6² sql topology. Compound 3 shows a 1-D → 3-D interdigitated architecture while 4 displays a 2-D → 3-D interdigitated architecture. The structural differences of the compounds indicate that the dicarboxylate anions and the central metal ions play important roles in the resulting structures of CPs. Optical band gaps and solid-state photoluminescent properties have also been studied.     

A series of 1-D zinc(II) coordination polymers with 3-D supramolecular networks: synthesis,structural investigation,and NBO analysis

Abstract

N,N′-Bis(pyridin-4-ylmethylene)naphthalene-1,5-diamine (L) acts as a bipyridine analogue linker ligand towards {Zn₇(μ₄-O)₂(OAc)₁₀}, {Zn₂(NCS)₂(OAc)₂}, and {Zn(N₃)₂} nodes and allows construction of three new 1-D coordination polymers, the linear chain [Zn₇(μ₄-O)₂(OAc)₁₀(L)]_n (1), [Zn(NCS)(OAc)(L)]_n (2) in ladder-type geometry and the zigzag chain [Zn(N₃)₂(L)]_n (3). Structural characterization reveals that in 1 acetate anionic ligands connect seven Zn(II) ions through the bridging coordination modes μ₃-η¹,η² and μ₂-η¹,η¹. The resulting heptanuclear node is located on an inversion center and therefore consists of four crystallographically distinct cations; their coordination spheres correspond to distorted octahedra or tetrahedra. The Zn(II) ions in polymer 2 exhibit distorted trigonal bipyramidal {ZnN₃O₂} coordination; μ₂-η¹,η¹ coordinated acetate and terminal thiocyanate ligands lead to inversion-symmetric [Zn₂(NCS)₂(OAc)₂] secondary building units (SBU), which are further linked by the N,N′-bipyridine analogue L. Terminal coordination of two anionic azide ligands and the bridging bipyridine L result in coordination polymer 3, in which the cations adopt distorted tetrahedral {ZnN₄} coordination. In all crystalline solids 1–3, adjacent 1-D chains interact through π–π stacking and non-classical (C???H···O, C???H···π) hydrogen bonds, leading to 3-D supramolecular architectures. Differences in their 3-D arrangement are due to variations in the anionic co-ligands, subtle conformational differences in the semi-rigid linker and the variable coordination sphere about the zinc cations. Thermogravimetric investigations indicate differences in both thermal stability and decomposition mode. Natural bond orbital (NBO) analysis provides a convenient basis for investigating the intramolecular bonding interactions and delocalization effects in these molecular systems. Finally, solids 1–3 exhibit intense luminescence at room temperature.     

Syntheses and structures of Cd(II) and Co(II) compounds of 4-[(3-pyridyl)methylamino]benzoate anion

Three coordination polymers containing Cd(II) and Co(II), connected via 4-[(3-pyridyl)methylamino]benzoate (L^?), have been synthesized in hydrothermal conditions. In [Cd(L)Cl] _n (1), adjacent Cd(II) cations are linked by carboxylates to give a dinuclear cluster. Pairs of L^? bridge the dinuclear cluster to form double helical chains, and these chains are further linked by Cl^? to produce a 4-connected net with (4²?·?6³?·?8) topology. [CdL₂] _n (2) contains 1-D ladder-like chains. The packing structure displays a 3-D supramolecular structure, with π?···?π interactions stabilizing the framework. [CoL₂] _n (3) has a 2-D extended supramolecular structure via π?···?π interactions of 1-D coordination polymers of 3. The crystal structures of 1–3 have been determined by single-crystal X-ray diffraction. Luminescent properties for 1 and 2 are discussed.     

Syntheses and structures of three coordination polymers based on 4-methylbenzenethiolates of Zn(II) and Cd(II) and bipyridine

Using 4-methylbenzenethiolates of Zn or Cd as precursors and 4,4′-bipyridine (4,4′-bpy) as bridges, we have synthesized three new Zn(II)/Cd(II) coordination polymers, {[Cd(4,4′-bpy)₂(NCS)₂] · 2(SC₆H₄CH₃-4)₂} _n (1), {[Zn(4,4′-bpy)(SC₆H₄CH₃-4)₂] · DMF} _n (2) and {[Zn(4,4′-bpy)(SC₆H₄CH₃-4)₂] · H₂O · 0.5CH₃OH} _n (3). Compound 1 is a 2-D sheet-like square polymer in which four 4,4′-bpy ligands and two isothiocyanate ligands complete the octahedral Cd(II) coordination sphere. Compounds 2 and 3 have similar coordination around Zn(II), but have different polymer structures. In 2, Zn(II) centers are linked via a bidentate 4,4′-bipyridine to form 1-D twisted arched chains, which is a new structural type for Zn(II). Compound 3 has 1-D zigzag chains. The 2-D sheets in 1 and 1-D chains in 2 and 3 are assembled via intermolecular C–H ··· π and C–H ··· S interactions into 3-D supramolecular networks. C–H ··· S interactions are a vital factor in constructing the sulfur-containing coordination polymers. Different coordination modes and packing schemes in 1–3 show that the guest molecule has a critical influence on formation of polymers.     

Synthesis and crystal structures of Cd(II), Ni(II), and Mn(II) complexes of 1H-benzotriazole-1-acetic acid

Three new complexes: [Cd(btaa)(bipy)(CH₃COO) · H₂O] _n (1), [Ni(btaa)₂(H₂O)₄ · 6H₂O] _n (2), and [Mn(btaa)₂(H₂O)₂] _n (3) (bipy = 2,2′-bipyridine, Hbtaa = 1H-benzotriazole-1-acetic acid) were prepared and characterized by IR, elemental analyses, thermogravimetric analyses, and single-crystal X-ray analyses. In 1, cadmium ions are linked by btaa ligands into 1-D linear chains; the chains are extended into layers through C–H ··· O hydrogen bonds and π–π stacking interactions. Complex 2 is a mononuclear structure, extended to a 3-D network through multiple intermolecular hydrogen bonds. In 3, manganese is bridged by carboxylate groups of btaa in the syn–skew bidentate mode in two directions to form a 2-D grid-like framework with a (4, 4) topology. The solid-state fluorescence spectrum of 1 shows that the excitation peak is at 355 nm while the maximum emission peak is at 424 nm.     

Syntheses,crystal structures,and fluorescent properties of two d10 metal complexes based on 2-(benzoimidazol-yl)methyl)-1H-1,2,4-triazole and 1,3,5-benzenetricarboxylate

Two d¹⁰ metal complexes, {[Zn(Hbtc)(bmt)]·DMF·5H₂O} _n (1) and {[Cd(Hbtc)(bmt)]·0.5DMF·0.5H₂O} _n (2) (H₃btc?=?1,3,5-benzenetricarboxylic acid, bmt?=?2-((benzoimidazol-yl)methyl)-1H-1,2,4-triazole), have been synthesized under solvothermal conditions by employing bmt and H₃btc. Single-crystal X-ray diffraction shows that Zn(II) ions are connected by bmt with bidentate-bridging coordination and by 1,3,5-benzenetricarboxylate with bis-monodentate coordination leading to the 2D structure of 1. Complex 2 exhibits a 2D layer structure, in which bmt coordinate tridentate-bridging to Cd(II) and 1,3,5-benzenetricarboxylates coordinate to Cd(II) unidentate/chelating. Photoluminescence and thermogravimetric analyses of the two complexes are investigated.     

Coumarin-naphthohydrazone ligand with a rare coordination mode to form Mn(II) and Co(II) 1-D coordination polymers: synthesis,characterization, and crystal structure

The hydrazone (E)-3-hydroxy-N’-(1-(2-oxo-2H-chromen-3-yl)ethylidene)-2-naphthohydrazide (H₂L) was synthesized from the reaction of 3-acetylcoumarin and 3-hydroxy-2-naphthoic hydrazide in methanol. Compounds [Mn(H₂L)(NO₃)₂(CH₃OH)]·CH₃OH (1a), [Mn(HL)(NO₃)(CH₃OH)]_n (1b), [Co(HL)(NO₃)(CH₃OH)]_n (2), and [Cu(HL)(NO₃)] (3) were obtained by reaction of an equimolar amount of H₂L with nitrate salts of Mn(II), Co(II), or Cu(II) in methanol. The reaction of ligand and Mn(NO₃)₂·4H₂O was also carried out in the presence of sodium azide which led to the 1-D coordination polymer, [Mn(HL)(N₃)(CH₃OH)]_n (4). All of the synthesized compounds were characterized by elemental analyses and spectroscopic methods. Single-crystal X-ray analysis of 1–4 indicated that H₂L is neutral (in 1a) or mononegative ligand (in 1b, 2, 3 and 4). In 1b, 2 and 4 the 1-D polymeric chain is found by a rare coordination mode of this kind of hydrazone ligand since the naphtholic oxygen is coordinated to the neighboring metal ions while the NH moiety of hydrazone remains intact, also confirmed by FT-IR spectroscopic studies. The thermal stability of 2 and 4 were also studied from 30–1000 °C.     

Coordination compounds of cobalt(II), nickel(II), and copper(II) with 4-(3-hydroxyphenyl)-1,2,4-triazole: Synthesis and study

New Co(II), Ni(II), and Cu(II) complexes with 4-(3-hydroxyphenyl)-1,2,4-triazole (L) with the compositions [Co₃L₆(H₂O)₅(C₂H₅OH)](NO₃)₆ · 2H₂O · C₂H₅OH (I), [Ni₃L₆(H₂O)₆](NO₃)₆ · 2H₂O (II), and [M₃L₆(H₂O)₆](ClO₄)₆ · nH₂O (M = Co2⁺, n = 2 (III); Ni²⁺, n = 2 (IV); Cu²⁺, n = 0 (V)) are synthesized. The complexes are studied by X-ray structure analysis, X-ray diffraction analysis, UV and IR spectroscopy, and the statistical magnetic susceptibility method. All compounds have the linear trinuclear structure. Ligand L is coordinated to the metal ions by the N(1) and N(2) atoms of the heterocycle according to the bidentate bridging mode. In all compounds the coordination polyhedron of the metal atom is a distorted octahedron. The molecular and crystal structures of compound I, [Co₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IIIa), and [Ni₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IVa) are determined.     

Complexes of unsymmetric bis-hydrazide ligands: crystal structures and properties

Two unsymmetric bis-aroyl-hydrazines, N′-(2-hydroxybenzoyl)isonicotinohydrazide (L1) and N′-(2-hydroxybenzoyl)nicotinohydrazide (L2), were synthesized through reactions of salicyl hydrazide with isonicotinoyl chloride and nicotinoyl chloride, respectively. Reactions of metal salts with L1 or L2 gave three new complexes, [Cd(L1)₂(SCN)₂] _n (1), [Zn(L1)₂Cl₂]?·?H₂O (2), and [Zn(L2)₂Cl₂] (3). Complex 1 features a 1-D double-chain structure built by SCN^– bridging six-coordinate Cd^II centers while 2 and 3 are mononuclear Zn^II complexes. In 1–3, isomeric ligands L1 and L2 coordinate with metal ions in a terminal coordination mode. Ligands L1 and L2 through O–H···N and N–H···O hydrogen-bonding interactions in 1–3 are crucial for the structure extension into 3-D supramolecular structures of 1 and 2, or 2-D sheet of 3. Complexes 1–3 emit interesting blue-green luminescence. Thermal behaviors of 1–3 as well as the specific rotation of 2 were also investigated.