Syntheses and Crystal Structures of Two Novel Linear Trinuclear Schiff Base Nickel(II) and Cadmium(II) Complexes

Two novel linear trinuclear Schiff base complexes, [Ni{Ni(C₁₇H₁₄Br₂N₂O₂)(NO₃)(H₂O)}₂] · 2MeOH · 2H₂O ( 1 ), and [Cd{Ni(C₂₅H₂₀N₂O₂)(CH₃COO)}₂] ( 2 ), were synthesized and characterized by elemental analyses, infrared spectroscopy, and X‐ray single crystal determinations. There are three bridges across the Ni‐M atom pairs (M is Ni for 1 , and Cd for 2 ) in each complex, involving two phenolate O atoms of a Schiff base ligand (N,N′‐bis(5‐bromosalicylidene)‐1,3‐propanediaminate (BSPD) for 1 and N,N′‐bis(2‐hydroxynaphthylmethenylimino)‐1,3‐propanediaminate (HNPD) for 2 ), and an O‐N‐O moiety of a μ‐nitrato group for 1 or an O‐C‐O moiety of a μ‐acetato group for 2 . In each of the complexes, the central M²⁺ is located on an inversion center and has an octahedral coordination involving four bridging O atoms from two Schiff base ligands in the equatorial plane and one O atom from each bridging nitrate or acetate group in the axial positions. The coordination around the terminal Ni²⁺ ions is also octahedral for 1 , but square pyramidal for 2 . The nitrate or acetate bridges linking the central and terminal metal ions are mutually trans. The Ni···M distances are 3.006(2) Å in 1 , and 3.175(2) Å in 2 .     

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 .     

Synthesis,Characterization and Crystal Structures of Four Dinuclear Schiff Base Nickel(II) and Copper(II) Complexes with Versatile Bridging Groups

Four novel Schiff base nickel(II) and copper(II) complexes, derived from the end‐on (μ_1,1‐N₃) azide, end‐to‐end (μ_1,3‐NCS) thiocyanate, or phenolate oxygen bridges, have been synthesized and their crystal structures determined by X‐ray diffraction methods. They are the dinuclear double end‐on azide‐bridged [Ni₂(L1)₂(MeCN)₂(μ_1,1‐N₃)₂]·MeOH ( 1 ), the dinuclear double end‐on azide‐bridged [Ni₂(L2)₂(MeOH)₂(μ_1,1‐N₃)₂][Ni₂(L2)₂(OH₂)₂(μ_1,1‐N₃)₂]·MeOH ( 2 ), the dinuclear double end‐to‐end thiocyanate‐bridged [Cu₂(L3)₂(μ_1,3‐NCS)₂] ( 3 ), and the dinuclear double phenolate O‐bridged [Cu₂(L4)₂(NCS)₂] ( 4 ), where HL1, HL2, HL3 and HL4 are four tridentate Schiff bases obtained by the condensation of 3,5‐dibromosalicylaldehyde with N‐ethylethane‐1,2‐diamine, of 3,5‐dichlorosalicylaldehyde with N‐methylpropane‐1,3‐diamine, of 3‐bromo‐5‐chlorosalicylaldehyde with 2‐aminomethylpyridine, and of 5‐nitrosalicylaldehyde with 2‐aminomethylpyridine, respectively. Each nickel(II) atom in 1 and 2 is in an octahedral coordination, while each copper(II) atom in 3 and 4 is in a square pyramidal coordination. There exists crystallographic inversion centre symmetry in each of the complexes.     

Solvent‐controlled Syntheses and Crystal Structures of a Pair of Novel Thiocyanate‐bridged Copper(II) Complexes Constructed from 4‐Bromo‐2‐(cyclopropyliminomethyl)phenolate

A pair of novel thiocyanate‐bridged polynuclear copper(II) complexes, [Cu₂(BCP)₂(NCS)₂]_n ( 1 ) and [Cu₂(BCP)₂(MeOH)(NCS)₂]₂ ( 2 ) [BCP = 4‐bromo‐2‐(cyclopropyliminomethyl)phenolate], have been obtained from an identical synthetic procedure and starting materials using solvents as the only independent variable. Complex 1 was synthesized and crystallized using EtOH as the solvent, while complex 2 was synthesized and crystallized using MeOH as the solvent. Both complexes show novel self‐assembled supramolecular structures in their crystals as elucidated by X‐ray analyses. The polymeric dinuclear complex 1 contains [Cu₂(BCP)₂(NCS)₂] units as the building blocks, crystallizes in the Pbca space group. The monomeric tetranuclear complex 2 contains [Cu₂(BCP)₂(MeOH)(NCS)₂] units as the building blocks, crystallizes in the P2₁/n space group.     

Anion‐controlled Syntheses and Crystal Structures of a Pair of Novel Azide‐bridged Copper(II) Complexes Constructed from 4‐Chloro‐2‐[(2‐dimethylaminoethylimino)methyl]phenol

A pair of novel azide‐bridged polynuclear copper(II) complexes, [CuL(μ_1,1‐N₃)]_n ( 1 ) and [Cu₄L₂(CH₃COO)₂(μ_1,1‐N₃)₄] ( 2 ) (L = 4‐chloro‐2‐[(2‐dimethylaminoethylimino)methyl]phenolate), have been obtained from the same Schiff base ligand and an identical synthetic procedure using anions of the metal salts as the only independent variable. Complex 1 was synthesized using copper(II) nitrate, while complex 2 was synthesized using the copper(II) acetate as the salt. Both of the complexes show novel supramolecular structures in their crystals as elucidated by X‐ray analyses. The polynuclear complex 1 contains [CuL(μ_1,1‐N₃)]_n units as the building blocks, crystallizes in the Pbca space group. The tetra‐nuclear complex 2 contains [Cu₄L₂(CH₃COO)₂(μ_1,1‐N₃)₄] units as the building blocks, crystallizes in the space group.     

Synthesis,Crystal Structures,and Urease Inhibitory Activities of Three Novel Thiocyanato‐bridged Polynuclear Schiff Base Cadmium(II) Complexes

Three novel thiocyanato‐bridged polynuclear cadmium(II) complexes, [Cd(HL1)(NCS)₂(μ_1,3‐NCS)]_n ( 1 ), [CdL2(μ_1,3‐NCS)₂]_n ( 2 ), and [CdL3(μ_1,3‐NCS)₂]_n ( 3 ) (L1 = N‐methyl‐N′‐(1‐pyridin‐2‐ylmethylidene)ethane‐1,2‐diamine, L2 = 2‐(cyclopropyliminomethyl)‐6‐methoxyphenol, L3 = 2‐(cyclopentyliminomethyl)‐6‐methoxyphenol), have been synthesized and structurally characterized by elemental analysis, IR spectra and single‐crystal X‐ray diffraction. Each cadmium(II) atom in the complexes is in an octahedral coordination. The urease inhibitory activities of the complexes were evaluated. All of them showed potent inhibitions against jack bean urease.     

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 Characterization,X‐ray Structures,and Solution Studies of Dinuclear Zinc(II) Complexes of Acyclic Schiff Base Ligands

Dizinc(II) complexes of two acyclic Schiff‐base ligands L1 ^– and L2 ^– were synthesized by Schiff base condensation of 2‐[3‐(2‐formylphenoxy)‐2‐hydroxypropoxy]benzaldehyde ( PL ) with 1,2‐diaminopropane and 1,2‐diaminoethane, respectively, in the presence of zinc(II) salts. The isolation of a selection of 2:1 (metal:ligand) complexes of zinc(II) was carried out and conductance measurements, IR, UV/Vis absorption, and fluorescence emission spectroscopy, as well as X‐ray diffraction were employed to probe the nature of the respective complexes in both solid and solution states. The molecular structure of [Zn₂ L1 (NO₃)₃] ( 1 ) complex consists of two six‐coordinate atoms, which are bridged by the deprotonated hydroxy group and one 1,3‐bridging nitrate anion. The structure of [Zn₂ L2 (NO₃)(H₂O)₂](NO₃)₂ · CH₃OH ( 3 ) consists of a dizinc cation and two nitrate anions as counterions. In compound 3 , each zinc atom is bound to water instead of a terminal nitrate anion in a distorted octahedral arrangement. The intermetallic separation distance of Zn ··· Zn in 3 (3.376 Å) is slightly smaller than 1 (3.403 Å) and is similar to that found in zinc phosphotriesterase (3.5 Å). The π–π interactions between the benzene rings of adjacent molecules in 3 are stronger than in 1 .     

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.     

三种酰腙类Schiff碱的锌配合物的合成、晶体结构与表征

采用不同的方法合成了3种酰腙的锌配合物[Zn(Lss)(phen)(DMF)](1)、{[Zn(HLdis)]_2·2CH_3OH}_n(2)和[Zn(Baf)_2]·CH_3OH (3),通过元素分析、红外光谱、紫外光谱和热重分析进行了表征,并经X射线单晶衍射分析它们晶体结构。1和3的晶体属于三斜晶系P1空间群,Zn(Ⅱ)的配位数为6;2属于单斜晶系P2_1/n空间群,Zn(Ⅱ)的配位数为5。3的前驱体是一种吡唑啉类化合物(C_(15)H_(14)N_2O_3,Pzl),它的晶体属于单斜晶系P2_1/c空间群;Pzl与锌离子配位时发生分子重排,开环产物HBaf以酰腙结构与Zn(Ⅱ)配位形成3。     

Syntheses,Characterization, and Crystal Structures of a Dinuclear Complex and Coordination Polymer of Mercury(II) with Schiff Base Ligands containing N3 and N4 Donors

Two dinuclear mercury(II) iodide compounds, [Hg₂(L)(I)₄] ( 1 ) and [(L′)Hg(μ‐I)₂HgI₂]_n ( 2 ) [L = N,N′‐bis(phenyl(pyridin‐2‐yl)methylene)propane‐1,2‐diamine and L′ = N‐(phenyl(pyridin‐2‐yl)methylene)propane‐1,2‐diamine] were synthesized and characterized. The molecular structures of [Hg₂(L)(I)₄] ( 1 ) and [(L′)Hg(μ‐I)₂HgI₂]_n ( 2 ), which were determined by single‐crystal X‐ray diffraction, indicate that each Hg^II in 1 has a distorted tetrahedral environment around the metal atom with a HgN₂I₂ chromophore, whereas in 2 one mercury(II) atom adopts a distorted tetrahedral arrangement with a HgI₄ chromophore and the other has a distorted square pyramidal environment with HgN₃I₂ chromophore. In the solid state, compound 2 consists of a 1D coordination polymer structure.     

Electrochemical Synthesis and Characterization of Tin(IV) Complexes of Dianionic Terdentate Schiff Base Ligands

Tin(IV) complexes of the series of dianionic terdentate Schiff bases N‐[(2‐pyrroyl)methylidene]‐N′‐tosylbenzene‐1,2‐diamine, (H₂L¹), N‐[(2‐hydroxyphenyl)methylidene]‐N′‐tosylbenzene‐1,2‐diamine (H₂L²) and some R substituted 2‐{[(2‐hydroxyphenyl)imino]methyl}phenols [R = H (H₂L³), 4,6‐(OCH₃)₂ (H₂L⁴), 3‐(OC₂H₅) (H₂L⁵) and 3,5‐Br₂ (H₂L⁶)] have been synthesized. The compounds were obtained by the electrochemical oxidation of a tin anode in a cell containing an acetonitrile solution of the corresponding ligand. The complex [SnL¹₂] was also obtained by reaction of SnCl₂·2H₂O and H₂L¹ in methanol in the presence of triethylamine. The crystal structure of the ligand [H₂L⁶] and the complexes [SnL¹₂] (1) , [SnL²₂] (2) , [SnL³₂] (3) and [SnL⁶₂] (6) were determined by X‐ray diffraction. In the complexes, the tin atom is in an octahedral environment coordinated by two dianionic terdentate ligands. Spectroscopic data for the complexes (IR, ¹H and ¹¹⁹Sn NMR and mass spectra) are discussed and related to structural information.     

Two Cadmium(II) Coordination Polymers based on Pamoic Acid and Different Polydentate N-donor Ligands: Syntheses,Crystal Structures,and Fluorescence Properties

Two new fluorescent coordination polymers based on pamoic acid and different polydentate N-donor ligands, namely {[Cd(PA)(TPTZ)(H₂O)](DMF)₂}_n ( 1 ) and [Cd(PA)(BIB)]_n ( 2 ) [H₂PA = pamoic acid, TPTZ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine, BIB = 1,4-bis(1-imidazolyl)benzene], were synthesized and characterized. Complex 1 showed a 1D zigzag chain structure with intramolecular hydrogen bonds. The 2D supramolecular structure in 1 was formed through π–π stacking interactions and intermolecular hydrogen bonds. Complex 2 displayed a 2D network structure. Intramolecular hydrogen bonds and π–π stacking interactions were observed in 2 . By studying the fluorescence sensing performance of two coordination polymers, complex 1 exhibited high selectivity for tracking Al³⁺ ion and complex 2 could discriminately detect inorganic or aliphatic amines with high selectivity.     

Synthesis,Characterization, and Crystal Structure of Mononuclear and Dinuclear Dioxomolybdenum(VI) Complexes with Tridentate Schiff‐base Ligands. Part 2

Mononuclear [MoO₂LD], and dinuclear [MoO₂L]₂ or [MoO₂L]₂ · D dixomolybdenum(VI) complexes have been prepared by the reaction of tridentate Schiff‐base ligands L with [MoO₂(acac)₂]. The Schiff‐base ligands have been synthesized from salicylaldehyde ( 1 , 1a , 1c , 1d ), 2‐hydroxy‐1‐naphthaldehyde ( 2 , 2c ) and 2‐hydroxy‐3‐methoxybenzaldehyde ( 3a , 3b , 3c , 3d , 3e ) with 2‐amino‐p‐cresol. All prepared complexes consist of cis‐MoO₂²⁺core coordinated by Schiff‐base ligand through two deprotonated hydroxyl groups and one imino nitrogen atom. The usual octahedral coordination around the molybdenum atoms is completed by the neutral ligand D (methanol, ethanol, dimethyl sulfoxide, imidazole or 4, 4′‐bipyridine). All compounds were characterized by elemental analyses, IR spectroscopy and some of them by X‐ray crystallography ( 1a , 2c , 3a , 3b , 3c and 3e ).     

具有不同类型桥基的双核Cu(Ⅱ)-Schiff碱配合物的合成和晶体结构

合成了３个分别以Ｃ２Ｏ２－４（［Ｃｕ２（Ｌ１）２（ｏｘ）］，１），ＡｃＯ－（［Ｃｕ２（ＡｃＯ）（Ｌ２）２］ＢＦ４，２）和酚氧（［Ｃｕ２（Ｌ３）２］（ＣｌＯ４）２，３）为桥基的双核铜配合物，并测定了１的复配合物［Ｃｕ２（Ｌ１）２（ｏｘ）］·［Ｆｅ（ＯＨ）２（Ｈ２Ｏ）４］ＣｌＯ４·Ｈ２Ｏ（１′）及２和３的晶体结构．Ｘ射线衍射结果表明：１′，２和３分别属于Ｆｄｄｄ，Ｐ２１／ｃ和Ｐ２１／ｃ空间群．晶胞参数：［Ｃｕ２（Ｌ１）２（ｏｘ）］［Ｆｅ（ＯＨ）２（Ｈ２Ｏ）４］ＣｌＯ４·Ｈ２Ｏ，ａ＝２．４３９０（４）ｎｍ，ｂ＝３．０５３８（６）ｎｍ，ｃ＝１．８４９４（６）ｎｍ，α＝β＝γ＝９０．００°；２，ａ＝０．８４７（１）ｎｍ，ｂ＝２．６５４２（８）ｎｍ，ｃ＝１．４１００（６）ｎｍ，β＝９１．３４（６）°；３，ａ＝０．７６４６（３）ｎｍ，ｂ＝１．６９８３（３）ｎｍ，ｃ＝２．４４１７（３）ｎｍ，β＝９７．１１°     

Syntheses, Characterization and Crystal Structures of New Nickel Complexes with 2,6-Bis(imino)pyridyl Ligands

Introduction In the past decade, the imino-complexes based on late transition metal have received significantly increasing attention for their excellent performance in the olefin polymerization area since Brookhart et al.[1-8]     

Silver(I) Complexes with Dithioether Ligands: Syntheses,Crystal Structures,and Fluorescence Properties

Two new dithioether ligands, 1,4‐bis[(phenylsulfanyl)methyl]naphthalene ( L¹ ), and 4,4′‐bis[(tert‐butylsulfanyl)methyl]biphenyl ( L² ) were synthesized and their silver(I) complexes were studied. Both Ag^I complexes, [Ag L¹ (NO₃)]_n ( 1 ) and [Ag L² (NO₃)]₂ ( 2 ), were synthesized at ambient temperature and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction analysis. Single‐crystal X‐ray analysis shows that complex 1 has a one‐dimensional helical chain structure with the neutral repeating unit [Ag(μ₂‐ L¹ )(NO₃)], whereas complex 2 has a centrosymmetrical neutral dinuclear structure. Moreover, complexes 1 and 2 are further extended into three‐dimensional supramolecular frameworks by hydrogen bonding and π–π stacking interactions, respectively. In addition, complexes 1 and 2 display strong blue emission in the solid state at room temperature.     

Coordinative Behaviour of Tridentate NS2‐Donor Ligands with Cadmium: Synthesis and Crystal Structures of New Complexes

The reaction of cadmium salts with various amounts of the tridentate NS₂‐chelating ligands 1‐(2‐mercapto‐acetophenone)‐4‐triphenylmethylthiosemicarbazone (H₂L¹) and 1‐(5‐mercapto‐3‐methyl‐1‐phenylpyrazole‐4‐carboxaldehyde)‐4‐triphenyl‐methylthiosemicarbazone (H₂L²) in the presence of bases like N‐methylimidazole (N–MeIm), pyridine (py) or triethylamine (Et₃N) provided a series of novel mono‐, di‐, tri‐ and heptanuclear cadmium complexes. They are of the general formulas [CdL¹(N–MeIm)]₂ ( 1 ), [CdL¹(py)]₂ ( 2 ), [CdL²(N–MeIm)]₂ ( 3 ), [CdL²(py)₃] · 0.25 C₆H₁₄ · 0.5 py ( 4 ), [Et₃NH]₂[Cd₃L ] · 7 MeOH ( 5 ), [Et₃NH]₂[Cd₃L ] ( 6 ) and [Et₃NH]₂[Cd₇L ] · 14 MeOH ( 7 ). The compounds were characterized by elemental analysis, IR‐ and ¹H‐NMR‐spectroscopy. Single‐crystal X‐ray structure analyses are reported for the complexes 2 , 4 , 5 and 7 . While 2 has a dimeric structure where each cadmium ion is pentacoordinated in a N₂S₃‐environment, 4 consists of a monomeric cadmium center with distorted octahedral N₄S₂‐coordination. The complexes 5 and 7 exhibit new structural types for tri‐ and heptanuclear cadmium compounds. It is shown that sulfur bridging might proceed via arylthiolates, iminothiolates or even both functions of the ligand. Aggregation is influenced by various factors like solvents, counterions and ligand properties.     

Syntheses, Characterization and Crystal Structures of New Nickel Complexes with 2,6-Bis （ imino ） pyridyl Ligands

In the past decade, the imino-complexes based on late transition metal have received significantly increasing attention for their excellent performance in the olefin polymerization area since Brookhart et al. demonstrated that the Ni( Ⅱ ) complexes incorporating with sterically hindered α-diimine ligands could be used in the polymerization of ethylene to form high molecular weight polymers.     

Copper(II) Complexes with Asymmetrical Schiff Base Ligands Derived from 2‐Acetylpyrazine

New copper(II) complexes of asymmetrical tetradentate Schiff bases containing pyrazine have been prepared and thoroughly characterised by elemental analysis, IR and electronic spectroscopy, mass spectrometry and magnetic measurements. Two alternative methods were used in the isolation of the complexes: template synthesis in the preparation of Cu(SalDpyz)ClO₄ (HSalDPyz = derived from the condensation of salicylaldehyde, acetylpyrazine and 1,2‐ethylendiamine, 2‐methyl‐1,2‐propylendiamine, 1,2‐phenylendiamine) and direct interaction between copper perchlorate and the corresponding Schiff base, as in the isolation of Cu(AEPyz)(ClO₄) (HAEPyz = (Z)‐4‐[2‐{[2‐{[(E)‐1‐(pyrazinyl)ethylidene]amino} ethyl)amino]‐3‐penten‐2‐one)]. [Cu(SalEn)(py)(OClO₃)][Cu(SalEn)(py)]ClO₄ ( 1 ) (SalEn = 4‐(2‐hydroxyphenyl)‐3‐aza‐3‐buten‐1‐amino, py = pyridine), metal precursor in the preparation of Cu(SalEnpyz)(ClO₄) (HSalEnpyz = 2‐{E(2‐{[(E)‐1‐(2‐pyrazinyl)ethylidene]amino}ethyl)imino]methyl}phenol), was crystallographically characterised. The crystal structure of [Cu(AEpyz)]ClO₄ ( 2 ) is also reported.