Synthesis and Structural Characterization of Co( Ⅱ ) Coordination Polymer [Co(μ-phth)(imi)2]n

A new cobalt( Ⅱ ) complex [Co(μ-phth)(imi)2]n (phth = o-phthalato, imi = imidazole)has been synthesized by the reaction of CoCl2 with disodium o-phthalate and imidazole. The crystal structure of the compound has been determined by single-crystal X-ray diffraction. The crystal is of monoclinic system, space group Pn with a = 8.405(1), b = 9.995(1), c = 9.996(2) (A),β= 104.479(2),V= 813.0(2) (A)3, Dc= 1.467 g/cm3, C14H12N4O4Co, Mr= 359.21, F(000) = 366,μ = 1.079 mm-1, Z = 2, R = 0.0483 and wR = 0.1209 for 1583 observed reflections (Ⅰ＞ 2σ(Ⅰ)). In the title complex, the Co(Ⅱ) ions are bridged by o-phthalate ligands in a bidentate mode, producing a zigzag infinite chain structure. Each four-coordinated cobalt( Ⅱ ) center was coordinated by two oxygen atoms and two nitrogen atoms to give a distorted tetrahedral geometry. The chains are linked by hydrogen bonds between oxygen atoms belonging to carboxylate groups and hydrogen atoms of imidazole molecules, forming an unusual two-dimensional coordination polymer.     

Synthesis and Structural Characterization of Co(Ⅱ) Coordination Polymer [Co(-phth)(imi_)2]_n

1 INTRODUCTION The polymeric metal complexes with extended structures are of great interest because of their useful chemical or physical properties[1]. Due to the noticeable fact that the aromatic polycarboxylate can provide versatile coordination mode and the non-coplanar structure of the carboxylate groups and the benzene rings, a lot of efforts in this field have been particularly directed to the preparation of aromatic polycarboxylate (such as phthalate, tere- phthalate and isophthal…     

Structure Studies on New Types of Macrocyclic Compounds Part V．Crystal Structure of Nickel（II） Complex of 5，12－Diphenyl－7，14－dimethyl－1，4，8，11－tetraazacyclotetradecane－N＇，N－diacetic Acid

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Hydrothermal syntheses, characterizations and crystal structures of a new lead(II) carboxylate-phosphonate with a double layer structure and a new nickel(II) carboxylate-phosphonate containing a hydrogen-bonded 2D layer with intercalation of ethylenediamines

Hydrothermal reactions of N,N-bis(phosphonomethyl)aminoacetic acid (HO₂CCH₂N(CH₂PO₃H₂)₂) with metal(II) salts afforded two new metal carboxylate-phosphonates, namely, Pb₂[O₂CCH₂N(CH₂PO₃)(CH₂PO₃H)]·H₂O (1) and {NH₃CH₂CH₂NH₃}{Ni[O₂CCH₂N(CH₂PO₃H)₂](H₂O)₂}₂ (2). Among two unique lead(II) ions in the asymmetric unit of complex 1, one is five coordinated by five phosphonate oxygen atoms from 5 ligands, whereas the other one is five-coordinated by a tridentate chelating ligand (1 N and 2 phosphonate O atoms) and two phosphonate oxygen atoms from two other ligands. The carboxylate group of the ligand remains non-coordinated. The bridging of above two types of lead(II) ions through phosphonate groups resulted in a 〈002〉 double layer with the carboxylate group of the ligand as a pendant group. These double layers are further interlinked via hydrogen bonds between the carboxylate groups into a 3D network. The nickel(II) ion in complex 2 is octahedrally coordinated by a tetradentate chelating ligand (two phosphonate oxygen atoms, one nitrogen and one carboxylate oxygen atoms) and two aqua ligands. These {Ni[O₂CCH₂N(CH₂PO₃H)₂][H₂O]₂}⁻ anions are further interlinked via hydrogen bonds between non-coordinated phosphonate oxygen atoms to form a 〈800〉 hydrogen bonded 2D layer. The 2H-protonated ethylenediamine cations are intercalated between two layers, forming hydrogen bonds with the non-coordinated carboxylate oxygen atoms. Results of magnetic measurements for complex 2 indicate that there is weak Curie-Weiss behavior with θ=−4.4 K indicating predominant antiferromagnetic interaction between the Ni(II) ions. Indication for magnetic low-dimension magnetism could not be detected.     

mer‐Di­aqua­bis(1H‐imidazole‐κN3)(orotato‐κ2N3,O4)­nickel(II)

The title mononuclear complex, [Ni(C₅H₂N₂O₄)(C₃H₄N₂)₂(H₂O)₂] or [Ni(HOr)(im)₂(H₂O)₂] (im is imidazole and H₃Or is orotic acid, or 2,6‐dioxo‐1,2,3,6‐tetra­hydro­pyrimidine‐4‐carboxylic acid), has been synthesized and the crystal structure determination is reported. The Ni^II ion in the complex has a distorted octahedral coordination geometry comprised of one deprotonated pyrimidine N atom and the adjacent carboxyl­ate O atom of the orotate ligand, two tertiary imidazole N atoms and two aqua ligands. An extensive three‐dimensional network of OW—H⋯O and N—H⋯O hydrogen bonds, and π–π and π–ring interactions are responsible for crystal stabilization.     

Synthesis and Crystal Structure of [Ni(bdpm)_2(OAc)]_2(N_3)_2·5H_2O(bdpm=Bis(3,5-dimethylpyrazol-1-yl)methane,OAc=CH_3COO~-)

1 INTRODUCTION Bis(pyrazol-1-yl)methane has been one of the po- pular polydentate nitrogen donor ligands due to its strong chelating coordination to transition metal ions as capping ligand. Coordination behavior of the li- gand is able to yield stable M-N-N-C-N-N six-mem- bered boat conformation[1, 2]. The complexes con- taining bdpm ligand have been widely synthesized and characterized in recent years, and exhibit the striking properties in catalysis, magnetism and so on[3-10]. For exa…     

萘氧乙酸及咪唑构筑的锌(Ⅱ)和铜(Ⅱ)配合物的水热合成、晶体结构及荧光性质

通过水热的方法合成得到2个由萘氧乙酸及咪唑配体构筑的配合物Zn(2-naph)₂(imi)₂ (1)和2Cu(2-naph)₂(imi)₂(H₂O)·Cu(2-naph)₂(imi)₂(H₂O) (2)(2-naph=2-naphthoxyacetate,imi=imidazole),它们的结构通过X射线晶体衍射、红外光谱和元素分析得到确定。在配合物1中,锌原子与来自不同2-萘氧乙酸配体中的2个羧酸氧原子和不同的咪唑分子中的2个氮原子形成了变形的四面体的几何构型。单个分子通过N-H…O氢键连接形成了一维链,然后在C-H…π弱作用下形成了三维结构。配合物2有2个独立的铜中心,它们有几乎相同的配位环境。每个铜中心都是变形的四方锥的配位构型。来自不同的2-萘氧乙酸配体中的2个羧酸氧原子和不同的咪唑分子中的2个氮原子形成了一个相对规则的四方锥赤道平面,配位水分子位于平面上方。配合物2的分子通过N-H…O和O-H…O氢键连接形成了二维结构。2个配合物的热稳定和固体荧光性质在本文中也得到了研究和讨论。     

Synthesis, structures, and magnetic properties of face-sharing heterodinuclear Ni(II)-Ln(III) (Ln = Eu, Gd, Tb, Dy) complexes

Heterodinuclear [(Ni (II)L)Ln (III)(hfac) 2(EtOH)] (H 3L = 1,1,1-tris[(salicylideneamino)methyl]ethane; Ln = Eu, Gd, Tb, and Dy; hfac = hexafluoroacetylacetonate) complexes ( 1.Ln) were prepared by treating [Ni(H 1.5L)]Cl 0.5 ( 1) with [Ln(hfac) 3(H 2O) 2] and triethylamine in ethanol (1:1:1). All 1.Ln complexes ( 1.Eu, 1.Gd, 1.Tb, and 1.Dy) crystallized in the triclinic space group P1 (No. 2) with Z = 2 with very similar structures. Each complex is a face-sharing dinuclear molecule. The Ni (II) ion is coordinated by the L (3-) ligand in a N 3O 3 coordination sphere, and the three phenolate oxygen atoms coordinate to an Ln (III) ion as bridging atoms. The Ln (III) ion is eight-coordinate, with four oxygen atoms of two hfac (-)'s, three phenolate oxygen atoms of L (3-), and one ethanol oxygen atom coordinated. Temperature-dependent magnetic susceptibility and field-dependent magnetization measurements showed a ferromagnetic interaction between Ni (II) and Gd (III) in 1.Gd. The Ni (II)-Ln (III) magnetic interactions in 1.Eu, 1.Tb, and 1.Dy were evaluated by comparing their magnetic susceptibilities with those of the isostructural Zn (II)-Ln (III) complexes, [(ZnL)Ln(hfac) 2(EtOH)] ( 2.Ln) containing a diamagnetic Zn (II) ion. A ferromagnetic interaction was indicated in 1.Tb and 1.Dy, while the interaction between Ni (II) and Eu (III) was negligible in 1.Eu. The magnetic behaviors of 1.Dy and 2.Dy were analyzed theoretically to give insight into the sublevel structures of the Dy (III) ion and its coupling with Ni (II). Frequency dependence in the ac susceptibility signals was observed in 1.Dy.     

Square-planar nickel(II) complexes with a tridentate Schiff base and monodentate heterocycles: self-assembly to dimeric and one-dimensional array via hydrogen bonding

Square-planar nickel(II) complex with tridentate ONO-donor 4-[(2-hydroxyphenyl)imino]-2-pentanone (H₂hpac) and imidazole (Himdz) are reported. The complex was synthesized in moderate yield by reacting Ni(O₂CCH₃)₂ · 4H₂O, H₂hpac and imidazole in 1 : 1 : 1 mole ratio and characterized by elemental analysis, IR, ¹H NMR spectroscopy. An X-ray structure determination of the complex has been completed. In the solid state, a one-dimensional assembly of the [Ni(hpac)(Himdz)] molecules is formed via intermolecular hydrogen bonds between the imidazole N–H groups and the coordinated hydroxyphenyl-O atoms.     

SYNTHESIS AND STRUCTURE OF A NEW TYPE OF COORDINA-TION COMPOUND OF Gd(Ⅲ) WITH H_2 CCH_2CH_2C(~+NH_2)C-HCOO-

<正> The crystal structure of gadolinium L-proline (Pro) complex [Gd2-(C5H9NO2)6 (H2O)6] (ClO4)6 has been determined. The complex crystallizes in the triclinic space group PI with following crystal data: a = 9. 906(3), b=13. 052(5), c = 13.703(5) A. α=109. 63(3), β=110.31(2), γ=100. 73(3)°, V=1470.3(9) A3.Mr=1710. 1, F(000) = 854,μ=26. 30 cm-1, Dc = 1. 931 g/cm3, Z=1.The structure was refined to the final R of 0. 048 for 3804 reflections. The structure is of one-dimensional chain, in which each gadolinium ion lies at the center of a distorted square antiprism of the eight oxygen atoms provided by four bridging carboxylate groups from four Pro ligands, a terminal carboxylate group from one terminal Pro ligand and three water molecules and the two neighbouring gadolinium ions are linked to each other through the two bridging carboxylate groups from the two Pro ligands. The prolines exist in the form of H2 CCH2CH2(+NH2)CHCOO-, and the complexions in the crystal are linked together by the net of hydrogen bo     

Structural, spectral, and magnetic properties of end-to-end di-mu-thiocyanato-bridged polymeric complexes of Ni(II) and Co(II). X-ray crystal structure of di-mu-thiocyanatobis(imidazole)nickel(II)

Thiocyanatonickel(II) and thiocyanatocobalt(II) complexes of the composition Ni(NCS)(2)(HIm)(2) (1) and Co(NCS)(2)(HIm)(2) (2), where HIm = imidazole, were prepared and studied. In particular, the crystal structure of Ni(NCS)(2)(HIm)(2) was determined by X-ray methods. This compound crystallizes in the monoclinic system, space group P2(1)/n, with a = 7.720(1) A, b = 5.557(1) A, c = 13.774(3) A, beta = 102.54(3) degrees, and Z = 2. Its structure consists of a one-dimensional polymeric chain in which nickel(II) ions are bridged by two thiocyanate groups bonding in an end-to-end fashion in a trans arrangement. The Ni...Ni distance is 5.557(1) A. The crystal packing is determined by the intermolecular hydrogen bonds and ring-stacking interactions. From their X-ray powder-diffraction patterns and IR spectra, the complexes 1 and 2 were found to be mutually isomorphous. The coordination compounds were identified and characterized using elemental analysis, magnetic measurements, and infrared and ligand-field spectra. Both complexes are first examples of ferromagnetically coupled one-dimensional polymeric compounds with double end-to-end thiocyanate bridges. The magnetic properties of the title compounds were investigated over the 1.9-290 K temperature range. The compounds exhibit long-range magnetic ordering with T(c) equal to 5.0 and 5.5 K for 1 and 2, respectively. Their isothermal magnetization was also studied. The magnetostructural properties of the nickel(II) compound obtained are discussed and compared to those of other double end-to-end thiocyanate-bridged nickel(II) complexes.     

Combining azide, carboxylate, and 2-pyridyloximate ligands in transition-metal chemistry: ferromagnetic Ni(II)5 clusters with a bowtie skeleton

The combined use of the anion of phenyl(2-pyridyl)ketone oxime (ppko(-)) and azides (N(3)(-)) in nickel(II) carboxylate chemistry has afforded two new Ni(II)(5) clusters, [Ni(5)(O(2)CR')(2)(N(3))(4)(ppko)(4)(MeOH)(4)] [R' = H (1), Me (2)]. The structurally unprecedented {Ni(5)(μ-N(3))(2)(μ(3)-N(3))(2)}(6+) cores of the two clusters are almost identical and contain the five Ni(II) atoms in a bowtie topology. Two N(3)(-) ions are end-on doubly bridging and the other two ions end-on triply bridging. The end-on μ(3)-N(3)(-) groups link the central Ni(II) atoms with the two peripheral metal ions on either side of the molecule, while the Ni···Ni bases of the triangles are each bridged by one end-on μ-N(3)(-) group. Variable-temperature, solid-state direct- (dc) and alternating-current (ac) magnetic susceptibility, and magnetization studies at 2.0 K were carried out on both complexes. The data indicate an overall ferromagnetic behavior and an S = 5 ground state for both compounds. The ac susceptibility studies on 1 reveal nonzero, frequency-dependent out-of-phase (χ(M)") signals at temperatures below ~3.5 K; complex 2 reveals no χ(M)" signals. However, single-crystal magnetization versus dc field scans at variable temperatures and variable sweep rates down to 0.04 K on 1 reveal no noticeable hysteresis loops, except very minor ones at 0.04 K assignable to weak intermolecular interactions propagated by nonclassical hydrogen bonds.     

Preparation and crystal structure of dual-functional precursor complex bis(acetylacetonato)nickel(II) with 4-pyridyltetrathiafulvalene

A tetrathiafulvalene (TTF) derivative 4-pyridyltetrathiafulvalene (Py-TTF) was synthesized. The 1:2 Ni complex 1 of bis(acetylacetonato)nickel(II) coordinated with Py-TTF was prepared. Complex 1 crystallizes in the monoclinic space group P2(1)/c. Two pyridyl N atoms from two different molecules of Py-TTF are coordinated in the trans configuration to the Ni ion of Ni(acac)2 to form an octahedral Ni complex, which is a precursor for both conducting and magnetic materials.     

Synthesis, Crystal Structure and Electrochemistry Properties of a (N,N'-Ethylene-bis(salicylaldiminato)) Nickel(II) Complex, [Ni_2(salen)_2]·NCS·NH_4

A new Ni(II) complex [Ni2(salen)2]·(NCS)·NH4 (salen = N,N’-bis(salicylidenea- mino)ethanato) has been prepared and structurally characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pbca with a = 16.8725(13), b = 19.0046(15), c = 20.0583(16) , Z = 8, V = 6431.8(9) 3, C33H32N6Ni2O4S1, Mr = 726.13, Dc = 1.500 g/cm3, F(000) = 3008, μ = 1.284 mm-1, the final R = 0.0394 and wR = 0.0767 for 4449 observed reflections with I > 2σ(I). The complex involves a N,N’-ethylene-bis(salicylaldiminato) Schiff base, an isothiocyanato anion and an ammonium cation. The nickle(II) ion adopts a distorted square coordination geometry with N2O2 set of Schiff base ligand. The complexes are linked into a dimmer via intermolecular hydrogen bonds and the [Ni(salen)] moieties are connected together to form a 2-D layer structure by intermolecular N–H…O hydrogen bonds and π-π stacking. Cyclic-voltammetry method was used to characterize electrochemically the complex.     

Copper(II) and nickel(II) complexes of binucleating macrocyclic bis(disulfide)tetramine ligands

Novel macrocyclic bis(disulfide)tetramine ligands and several Cu(II) and Ni(II) complexes of them with additional ligands have been synthesized by the oxidative coupling of linear tetradentate N2S2 tetramines with iodine. Facile demetalation of the Ni(II) oxidation products affords the free 20-membered macrocycles meso-9 and rac-9 and the 22-membered macrocycle 16, all of which are potentially octadentate N4S4 ligands. X-ray structure analyses reveal distinctly different conformations for the two isomers of 9; meso-9 shows a stepped conformation in profile with the disulfide groups corresponding to the rise of the step, whereas rac-9 exhibits a V conformation with the disulfide groups near the vertex of the V. No metal complexes of rac-9 have been isolated. Crystallographic studies of three Cu(II) complexes reveal that depending upon the size of the macrocyclic ligand and the nature of the additional ligands (I-, NCO-, and CH3CN), the Cu(II) coordination geometry shows considerable variation (plasticity), with substantial changes in the Cu(II)-disulfide bonding. Thus, a diiodide salt contains six-coordinate Cu(II) to which all four bridging disulfide sulfur atoms form strong equatorial bonds. In contrast, isocyanato complexes of the 20- and 22-membered macrocycles exhibit trigonal-bipyramidal Cu(II) and distorted cis-octahedral Cu(II) geometries, respectively, having only one and no short equatorially bound sulfur atoms. The coordination geometry of the latter complex can also be described as four-coordinate seesaw with two semicoordinated S(disulfide) ligands. Disulfide-->Cu(II) ligand-to-metal charge transfer absorptions of both isocyanato-containing Cu(II) species appear too weak to observe, probably because of poor overlap of the sulfur orbitals with the Cu(II) d-vacancy. The dual disulfide-bridged Ni(II) units of the crystallographically characterized octahedral Ni(II) complex of meso-9 with axial iodide and acetonitrile ligands promote substantial antiferromagnetic coupling (J = -13.0(2) cm-1).     

Co[HO2C(CH2)3NH(CH2PO3H)2]2: a new canted antiferromagnet

A new cobalt(II) carboxylate-phosphonate, namely, Co[HO2C(CH2)3NH(CH2PO3H)2]2, with a layered architecture has been synthesized by hydrothermal reactions. The Co(II) ion in the title compound is octahedrally coordinated by six phosphonate oxygen atoms from four carboxylate phosphonate ligands. Neighboring CoO6 octahedra are interconnected by phosphonate groups into a 2D layer with a 4,4-net topology. Adjacent layers are further cross-linked via hydrogen bonds between the noncoordinate carboxylate groups and noncoordinate phosphonate oxygens. The ac and dc magnetic susceptibility and magnetization measurements indicate that Co[HO2C(CH2) 3NH(CH2PO3H)2]2 is a canted antiferromagnet with T(c) = 8.75 K.     

氢键构筑的二维网状结构镍配合物[Ni(en)2(dpas)2]的合成、晶体结构及电化学性质

A new 2D Hydrogen-bonded network complex [Ni(en)2(dpas)2] (Nadpas=sodium diphenylamine sulphonic acid salt,en=ethanediamine) has been synthesized in aqueous solution,and characterized by elemental analysis,IR. The crystal structure was determined by single-crystal X-ray diffraction. The complex crystallizes in space group P21/c,with cell parameters a=0.605 6(5)nm,b=1.448 1(5) nm,c=1.711 9(5)nm,β=93.257(5)°,and V=1.498 9(14) nm3,Dc=1.497 g·cm-3,Z=2,F (000)=708,R=0.027 7,wR=0.072 5. The crystal structure shows that the nickel atom is coordinated with four nitrogen atoms from the two en and two oxygen atoms from two dpas to form a mononuclear complex. Furthermore,the adjacent complex units are extended into a 2D supramolecular network through hydrogen bonds.     

Ferromagnetism in malonato-bridged copper(II) complexes. Synthesis,crystal structures,and magnetic properties of [[Cu(H2O)3][Cu(mal)2(H2O)]]n and [[Cu(H2O)4]2[Cu(mal)2(H2O)]][Cu(mal)2(H2O)2][[Cu(H2O)4][Cu(mal)2(H2O)2][(H2mal = malonic acid)

Three malonato-bridged copper(II) complexes of the formulas [[Cu(H2O)3][Cu(C3H2O4)2(H2O)]]n (1), [[Cu(H2O)4]2[Cu(C3H2O4)2(H2O)]] [Cu(C3H2O4)2(H2O)2][[Cu(H2O)4][Cu(C3H2O4)2(H2O)2]] (2), and [Cu(H2O)4][Cu(C3H2O4)2(H2O)2] (3) (C3H2O4 = malonate dianion) have been prepared, and the structures of the two former have been solved by X-ray diffraction methods. The structure of compound 3 was already known. Complex 1 crystallizes in the orthorhombic space group Pcab, Z = 8, with unit cell parameters of a = 10.339(1) A, b = 13.222(2) A, and c = 17.394(4) A. Complex 2 crystallizes in the monoclinic space group P2/c, Z = 4, with unit cell parameters of a = 21.100(4) A, b = 21.088(4) A, c = 14.007(2) A, and beta = 115.93(2) degrees. Complex 1 is a chain compound with a regular alternation of aquabis(malonato)copper(II) and triaquacopper(II) units developing along the z axis. The aquabis(malonato)copper(II) unit acts as a bridging ligand through two slightly different trans-carboxylato groups exhibiting an anti-syn coordination mode. The four carboxylate oxygens, in the basal plane, and the one water molecule, in the apical position, describe a distorted square pyramid around Cu1, whereas the same metal surroundings are observed around Cu2 but with three water molecules and one carboxylate oxygen building the equatorial plane and a carboxylate oxygen from another malonato filling the apical site. Complex 2 is made up of discrete mono-, di-, and trinuclear copper(II) complexes of the formulas [Cu(C3H2O4)2(H2O)2]2-, [[Cu(H2O)4] [Cu(C3H2O4)2(H2O)2]], and [[Cu(H2O)4]2[Cu(C3H2O4)2(H2O)]]2+, respectively, which coexist in a single crystal. The copper environment in the mononuclear unit is that of an elongated octahedron with four carboxylate oxygens building the equatorial plane and two water molecules assuming the axial positions. The neutral dinuclear unit contains two types of copper atoms, one that is six-coordinated, as in the mononuclear entity, and another that is distorted square pyramidal with four water molecules building the basal plane and a carboxylate oxygen in the apical position. The overall structure of this dinuclear entity is nearly identical to that of compound 3. Finally, the cationic trimer consists of an aquabis(malonato)copper(II) complex that acts as a bismonodentate ligand through two cis-carboxylato groups (anti-syn coordination mode) toward two tetraaqua-copper(II) terminal units. The environment of the copper atoms is distorted square pyramidal with four carboxylate oxygens (four water molecules) building the basal plane of the central (terminal) copper atom and a water molecule (a carboxylate oxygen) filling the axial position. The magnetic properties of 1-3 have been investigated in the temperature range 1.9-290 K. Overall, ferromagnetic behavior is observed in the three cases: two weak, alternating intrachain ferromagnetic interactions (J = 3.0 cm-1 and alpha J = 1.9 cm-1 with H = -J sigma i[S2i.S2i-1 + alpha S2i.S2i+1]) occur in 1, whereas the magnetic behavior of 2 is the sum of a magnetically isolated spin doublet and ferromagnetically coupled di- (J3 = 1.8 cm-1 from the magnetic study of the model complex 3) and trinuclear (J = 1.2 cm-1 with H = -J (S1.S2 + S1.S3) copper(II) units. The exchange pathway that accounts for the ferromagnetic coupling, through an anti-syn carboxylato bridge, is discussed in the light of the available magneto-structural data.     

Synthesis,Spectral, Thermal Studies of Co(II), Ni(II), Cu(II) and Zn(II)‐arginato Complexes. Crystal Structure of Monoaquabis(arginato‐κO,κN)copper(II). [Cu(arg)2(H2O)].NaNO3

Transition metal complexes of arginine (using Co(II), Ni(II), Cu(II) and Zn(II) cations separately) were synthesized and characterized by FTIR, TG/DTA‐DrTG, UV‐Vis spectroscopy and elemental analysis methods. Cu(II)‐Arg complex crystals was found suitable for x‐ray diffraction studies. It was contained, one mole Cu^II and Na⁺ ions, two arginate ligands, one coordinated aqua ligand and one solvent NO₃^? group in the asymmetric unit. The principle coordination sites of metal atom have been occupied by two N atoms of arginate ligands, two carboxylate O atoms, while the apical site was occupied by one O atom for Cu^II cation and two O atoms for Co^II, Ni^II, Zn^II atoms of aqua ligands. Although Cu^II ion adopts a square pyramidal geometry of the structure. Co^II, Ni^II, Zn^II cations have octahedral due to coordination number of these metals. Neighbouring chains were linked together to form a three‐dimensional network via hydrogen‐bonding between coordinated water molecule, amino atoms and O atoms of the bridging carboxylate groups. Cu^II complex was crystallized in the monoclinic space group P2₁, a = 8.4407(5) Å, b = 12.0976(5) Å, c = 10.2448(6) Å, V = 1041.03(10) ų, Z = 2. Structures of the other metal complexes were similar to CuII complex, because of their spectroscopic studies have in agreement with each other. Copper complex has shown DNA like helix chain structure. Lastly, anti‐bacterial, anti‐microbial and anti‐fungal biological activities of complexes were investigated.     

Hydrogen bonding effects on the electronic configuration of five-coordinate high-spin iron(II) porphyrinates

The characterization of a new five-coordinate derivative of (2-methylimidazole)(tetraphenylporphinato)iron(II) provides new and unique information about the effects of forming a hydrogen bond to the coordinated imidazole on the geometric and electronic structure of iron in these species. The complex studied has two crystallographically distinct iron sites; one site has an axial imidazole ligand modified by an external hydrogen bond, and the other site has an axial imidazole ligand with no external interactions. The iron atoms at the two sites have distinct geometric features, as revealed in their molecular structures, and distinct electronic structures, as shown by M?ssbauer spectroscopy, although both are high spin (S = 2). The molecule with the external hydrogen bond has longer equatorial Fe-N(p) bonds, a larger displacement of the iron atom out of the porphyrin plane, and a shorter axial bond compared to its counterpart with no hydrogen bonding. The M?ssbauer features are distinct for the two sites, with differing quadrupole splitting and isomer shift values and probably differing signs for the quadrupole splitting as shown by variable-temperature measurements in applied magnetic field. These features are consistent with a significant change in the nature of the doubly populated d orbital and are all in the direction of the dichotomy displayed by related imidazole and imidazolate species where deprotonation leads to major differences. The results points out the possible effects of strong hydrogen bonding in heme proteins.