Synthesis,crystal, and molecular structure of coordination polymers constructed by self-assembly of NiN<Subscript>4</Subscript> cores with 2,2′-iminodibenzoate and nitroprusside ions

Two coordination compounds of compositions [Ni(L¹)(idba)(H₂O)]·1.5 H₂O (1) and [Ni(L²)Fe(CN)₅NO]·C₂H₅OH (2) where L¹ is N, N′-bis(3-aminopropyl)ethylenediamine, L² is 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentaene, and idba^2? is 2,2′-iminodibenzoate have been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic space group P2₁/n (No. 14) with a=9.810(2) Å, b=10.230(2) Å, c=25.350(5) Å, V=2543.6(9) Å³, Z=4, and R=0.0727. The nickel atom is six-coordinated by four N atoms of amine and two O atoms of water and idba^2?. The molecular packing of the complex comprises of an infinite one-dimensional layered network in which the molecules in the crystal are held together by a system of hydrogen bonding. Complex 2, however, crystallizes in the space group C2/c (No. 15) of the monoclinic system with a=19.7990(4) Å, b=14.9440(3) Å, c=19.8800(3) Å, V=5115.90(17) Å³, Z=4, and R=0.0540. The Ni ion in compound 2 has a slightly distorted octahedral arrangement of the N₄ donor atoms of primary ligand L² and two N-donor atoms of the secondary nitroprusside ligand. The structure of 2 displays an extended one-dimensional network formed by linear [—Ni—NC—Fe—CN—] units. A cyclic voltammetric study shows that compound 1 undergoes a quasireversible oxidation attributable to Ni²⁺ → Ni³⁺ in the range 300–420 mV vs SCE.     

Synthesis and structure of Pt(II) acetamidate complexes containing <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethyl-substituted ethylenediamine and trimethylenediamine

Reactions of acetamide with platinum(II) diamines [Pt(N,N-DimeEn)Cl₂], [Pt(Tm)Cl₂], and [Pt(N,N-DimeTm)Cl₂] (N,N-DimeEn = (CH₃)₂N(CH₂)₂NH₂, Tm = NH₂(CH₂)₃NH₂, N,N-DimeTm = (CH₃)₂N(CH₂)₃NH₂) with preliminary precipitation of chlorine ions by silver salts gave binuclear Pt(II) acetamidates [Pt₂(CH₃)₂N(CH₂)₂NH₂)₂(μ-NHCOCH₃)₂](NO₃)₂ · H₂O (I), [Pt₂(NH₂(CH₂)₃NH₂)₂)(μ-NHCOCH₃)₂](NO₃)₂ · H₂O (II), and [Pt₂(CH₃)₂N(CH₂)₃NH₂)₂(μ-NHCOCH₃)₂](HSO₄)₂ (III), whose crystal structures were determined. Crystals of I are monoclinic: a = 14.459(2) Å, b = 17.197(3) Å, c = 9.822(2) Å, β = 105.923(10)°, V = 3348.6(8) ų, space group P2(1)/c, Z = 4, R _hkl = 0.0419 for 6663 reflections. Complex I is a binuclear acetamidate with bridging (NHCOCH₃)^? ligands, one of which is bound to two Pt atoms through the N and O atoms, and the other ligand is bound only through the N atom. The Pt-Pt distance is 2.987(1) Å. Crystals of II are monoclinic: a = 10.213(7) Å, b = 13.373(9) Å, c = 16.533(11) Å, β = 97.971(9)°, V = 2236(3) ų, space group P2(1)/n, Z = 4, R _hkl = 0.557 for 6462 reflections. The Pt-Pt distance is 3.057(1) Å. Crystals of III are monoclinic: a = 10.557(12) Å, b = 18.531(2) Å, c = 14.4744(17) Å, β = 108.705(2)°, V = 2682(5) ų, space group P2(1)/n, Z = 4, R _hkl = 0.569 for 8506 reflections. The Pt-Pt distance is 3.202(1) Å. Complexes II and III are binuclear acetamidates, in which two chelating Pt(Tm) or Pt(N,N-DimeTm) moieties are coordinated through the N and O atoms of (NHCOCH₃)^? cis-bridges.     

Synthesis,crystal structure,and vibrational spectrum of lithium <Emphasis Type="Italic">N</Emphasis>-(4′-benzo-15-crown-5)-5-bromo-2-hydroxyphenylaldiminatozinc perchlorate dihydrate

The synthesis, the IR absorption spectrum, and X-ray diffraction analysis of the complex [ZnLi(L¹)₂(H₂O)](ClO₄) · H₂O (I) (HL¹ = N-(4′-benzo-15-crown-5)-5-bromo-2-hydroxyphenylaldimine) are described. The crystals of I are monoclinic, a = 19.840(4) Å, b = 13.947(3) Å, c = 19.956(4) Å, β = 117.06(3)°, V = 4917.4(17) ų, Z = 4, space group P2₁/n, R = 0.0609 for 1409 reflections with I > 2σ(I). In the complex cation [ZnLi(L¹)₂(H₂O)]⁺, the Zn atom is bound to a distorted tetrahedral array of two N atoms (av. Zn-N, 2.027(10) Å) and two O atoms (av. Zn-O, 1.8968(8) Å) of two deprotonated L¹ ligands. The Li atom linked to the five ether oxygen atoms (av. Li-O_ether, 2.254(3) Å) sits atop the benzo-15-crown-5 (B15C5) macrocyclic plane of one coordinated L¹ ligand. The Li coordination is completed by water oxygen (Li-O(w1), 1.83(5) Å). The B15C5 cavity of the second coordinated ligand L¹ is vacant.     

Synthesis,crystal and molecular structures of 1D and 2D supramers of copper(II) with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-{bis(pyridin-2-yl) benzylidene}butane-1,4-diamine

Reaction of copper(II) perchlorate with N,N′-{bis(pyridin-2-yl)benzylidene}butane-1,4-diamine (bpbd) yielded monoclinic crystals of bluish green [Cu(bpbd)(ClO₄)]ClO₄ (1), and a similar reaction in presence of azide anion, N₃ ^? formed monoclinic crystals of dark green [Cu(bpbd)(N₃)]₂ClO₄ (2). Crystal data for 1: space group P21/c, Z=4, a=17.3968(4) Å, b=9.3182(2) Å, c=17.6794(4) Å, β=102.149(1)°. The geometry around Cu(II) centre is distorted square pyramidal with axial site occupied by O atom of perchlorate and in plane Cu is bonded to four N atoms of the organic ligand. The intermolecular C–H...π stacking in 1 forms a zigzag chain (1D) supramer. Crystal data for 2: space group C2/c, Z=4, a=22.3109(4) Å, b=17.7832(3) Å, c=14.3389(2) Å, β=92.553(1)°. In dinuclear 2, Cu(II) has tetragonally distorted octahedral geometry coordinated by four N atoms of bpbd, with the fifth and sixth positions occupied by N atoms of two end-on bridging azides. The π...π interaction leads to a two dimensional (2D) sheet within which the counter anions are embedded. Both the compounds 1 and 2 show simple paramagnetism. Cyclic voltammetry and fluorescence spectra are also reported.     

Low-dimensional compounds containing cyano groups. XV. Preparation,crystal structure and spectral properties of three copper(II) nitrosodicyanomethanide complexes

We describe the preparation and crystal structures of the ionic complexes [Cu(bipy)₂{ONC(CN)₂}]CF₃SO₃ (1b), [Cu(phen)₂{ONC(CN)₂}]PF₆ (2p) and [Cu(bipy)₂{ONC(CN)₂}]PF₆ (2b). In the complex cations [Cu(L)₂{ONC(CN)₂}]⁺ (L is 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen)) the two molecules of bipy or phen coordinate to the copper atom through two nitrogen atoms along with the oxygen atom of the nitrosodicyanomethanide anion, ONC(CN) ₂ ^? , to form a {CuN₄O} chromophore with a distorted square pyramidal coordination sphere in (1b) and (2b) and a distorted trigonal bipyramidal geometry in (2p). The basal plane in (1b) and (2b) is formed by an oxygen atom coordinated at the Cu1–O1 distance of 1.990(2) and 2.002(2) Å, respectively, and three nitrogen atoms coordinated to the copper atom at similar distances with the average of 2.01(2) and 2.00(3) Å, respectively. The axial position is occupied by the fourth N atom at the longer distance of 2.222(2) and 2.185(2) Å, respectively. The trifluoromethanesulfonate anion (triflate), CF₃SO ₃ ^? , in (1b) might be considered as very weakly coordinated in the opposite axial position (Cu1–O2 = 2.719(2) Å). The equatorial plane in (2p) is formed by an oxygen atom coordinated at the Cu1–O1 distance of 1.975(3) Å, and two nitrogen atoms from different phen molecules coordinated to the copper atom at the same distance within 2 σ with the average distance of 2.124(2) Å. The axial positions are occupied by remaining two nitrogen atoms coordinated at shorter distance (average Cu–N = 1.99(3) Å). The hexafluorophosphate anions, PF ₆ ^? , in (2p) and (2b) remain uncoordinated. Besides the ionic forces, the structures of (2p) and (2b) may be stabilized by very weak C–H···F whereas the structure of (1b) by very weak C–H···F, C–H···O and C–H···N hydrogen bonds. The structural–spectral correlations are also discussed.     

Bis[7-(1,3-dioxolan-2-yl-methyl)-3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione] dichlorozinc(II) 0.47-hydrate: the role of secondary bond in forming the four-fold helix Chain

Single crystals of Zn^IICl₂(C₁₁H₁₄N₄O₄)₂ · 0.47H₂O (I) were obtained from an aqueous solution of ZnCl₂ and doxofylline in a 1: 2 molar ratio, and the crystal structure was determined by single-crystal X-ray diffraction (tetragonal, space group P4₁, Z = 8, a = b = 14.9481(5), c = 25.4778(11) Å). In the compound I, Zn²⁺ cation is located at the center of a distorted tetragonal coordination polyhedron, formed by the two Cl atoms and two N atoms of doxofylline ligands. In the crystal, crystallographically independent molecules of the compound I are bonded alternatively together by Cl···N secondary bonds to form four-fold helix chain along the z axis.     

Crystal and molecular structure of [Au(C<Subscript>14</Subscript>H<Subscript>24</Subscript>N<Subscript>4</Subscript>)][H<Subscript>3</Subscript>O](ClO<Subscript>4</Subscript>)<Subscript>4</Subscript>

The crystal and molecular structure of doubly protonated tetraazamacrocyclic complex of gold(III) [Au(C₁₄H₂₄N₄)][H₃O](ClO₄)₄ has been determined. The crystals are monoclinic: a = 11.158(2) Å, b = 8.243(1) Å, c = 14.756(2) Å; β = 98.65(1)°, V = 1341.8(3) ų, Z = 2, ρ(calc) = 1.134 g/cm³, space group P2₁/n. The structure is built of almost flat centrosymmetrical Au(C₁₄H₂₄N₄)]³⁺ and [H₃O]⁺ cations and [ClO₄]^? anions. The gold atom is coordinated with four nitrogen atoms of the ligand forming a flat square. The coordinated ligand is protonated at its γ-carbon atoms of the two six-membered chelate rings. The Au-N bond lengths are almost identical (the mean value is 1.994 Å). The six-membered rings of the complex contain C=N diimine bonds. The [H₃O]⁺ oxonium ion has H-bonds with the oxygen atoms of perchlorate ions.     

Tetrakis [<Emphasis Type="Italic">N</Emphasis>-(2-pyridyl) sulfonamide] di palladium: synthesize,X-ray diffraction,antibacterial properties and as a novel binuclear Pd-complex for coupling reactions

The N-(2-pyridyl) 4-toluene sulfonamide as a free ligand (PTS) was prepared from the reaction of 2-amino pyridine and 4-toluenesulfonyl chloride in the presence of potassium hydroxide solution 1 M as a base and THF was used as a solvent. The complex tetrakis [N-(2-pyridyl) sulfonamide] di palladium (1) (Pd₂L₄) was also prepared from the reaction of PdCl₂(CH₃CN)₂ using (PTS) in the presence of NaOH 0.5 M and its application in Heck and Suzuki reactions. This complex consists of a binuclear unit consisting of four ligands linked to two palladium atoms via the nitrogen of pyridines ring and the nitrogen of sulfonamides. These compounds were confirmed by FT-IR and ¹H NMR spectroscopy. Moreover, the structure of the complex was studied by single-crystal X-ray diffraction method. The green crystal of Pd₂L₄ [L = N-(2-pyridyl) sulfonamide](1) was found to crystallize in the monoclinic space group C2/c with a = 18.2013(19), b = 19.7544(16), c = 17.2898(19) Å, β = 120.179(8) °; V = 5374.0(9) ų; Z = 4; the final R ₁ = 0.0894, wR ₂ = 0.1754 (or 5867 observed reflections and 318 variables). The Pd–Pd distance is 2.567(2) Å. In addition, PTS and Pd₂L₄ presented different antibacterial behaviors. The free ligand was active against Staphylococcus aureus and Escherichia coli, but the complex was inactive against them.     

Structural characterization of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-bis(2-methoxyethyl) -4,5-bis(2,4,6-trimethylphenyl)imidazolinium hexafluorophosphate

The crystal and molecular structure of the N,N′-bis(2-methoxyethyl)-4,5-bis(2,4,6-trimethylphenyl)- imidazolinium hexafluorophosphate, which is the first example of 1,3- and 4,5-disubstituted imidazolinium salts, have been determined and characterized by X-ray single crystal diffraction technique,¹H, ¹³C, ³¹P and ¹⁹F NMR spectroscopy. The compound, C₂₇H₃₉N₂O₂ ⁺·PF₆ ^?, crystallizes in the orthorhombic space group Pba2 with a = 15.8139(4) Å, b = 22.9346(7) Å, c = 8.069(3) Å. Two charge-assisted C–H\(\cdots\)F type crystal packing interactions between the imidazolinium C–H bonds and the F atoms of hexafluorophosphate counteranions build up zigzag chains along a-axis of the unit cell and indicate that the C–H bonds of the imidazolinium ring are also polarized. In addition, the title salt was modeled by DFT calculations in order to verify charge transfer mechanism observed in its imidazolinium ring.     

Diphenylguanidinium (ethylenediaminetetraacetato)hydroxogermanate hydrate (HDphg)[Ge(OH)(Edta)] · H<Subscript>2</Subscript>O: Synthesis,physicochemical characterization,and crystal structure

The onium compound based on the germanium(IV) complex with ethylenediamine-N,N,N ¹,N ¹-tetraacetic acid (H₄Edta) and diphenylguanidine (Dphg), (HDphg)[Ge(OH)(Edta)] · H₂O, has been isolated in the solid state and studied by physicochemical methods. Its crystal structure has been determined by the X-ray diffraction method. The crystals are monoclinic, a = 7.0179(9) Å, b = 28.797(8) Å, c = 13.477(2) Å, β = 104.301(12)°, V = 2639.3(9) Å₃, Z = 4, space group P2₁/c, R = 0.045 for 2524 reflections with I > 2σ(I). The onium compound is built of diphenylguanidinium cations HDphg⁺, [Ge(OH)(Edta)]^? anions, and water molecules of crystallization. In the complex anion, the Ge atom is coordinated by two nitrogen atoms and three oxygen atoms of three acetate arms of the pentadentate chelating ligand Edta^4? (av. Ge-N, 2.095(4) Å; Ge-O, 1.891(3) Å). The fourth acetate arm is deprotonated and is not involved in coordination with the metal. The coordination of the metal atom is completed to an octahedral one by the O atom of the hydroxo ligand (Ge-OH 1.759(3) Å). The structural units in crystal are linked by a system of hydrogen bonds.     

Crystal structure,DFT study,antimicrobial properties and DNA cleavage potential and thermal behavior of some new mercury complexes

In this study, a new bidentate Schiff base ligand (L) entitled as N,N’-bis(dimethylaminocinnamaldehyde)-2,2-dimethyl-1,3-propanediamine and its mercury complexes were synthesized. The Schiff base ligand and its complexes were characterized using FT-IR, ¹H-, ¹³C-NMR spectroscopy, molar conductivity and electronic spectral study. Regarding physical and spectral data, the general formula for the complexes was suggested as HgLX₂ (L = Schiff base ligand and X = Cl^?, Br^?, I^?, SCN^?, N₃ ^?). For structural identification of these complexes, crystal structure of mercury iodide complex was analyzed as typical one. In the structure of this complex, Hg ion is surrounded by 2 iodide ions and 2 N atoms from the Schiff base ligand to form a four-coordinated mercury complex in triclinic system with space group of P ₁. Angular index (τ ₄) value was evaluated equal to 0.85, so the geometry around the mercury ion in this complex can be described as trigonal pyramid. A layered supramolecular structure for HgLI₂ complex is stabilized by C–H···I and C–H···π interactions in solid state. DFT study on the ligand and its complexes was also carried out, and then some calculated and experimental structural parameters of HgLI₂ were compared. Thermal behaviors of the titled compounds were investigated by thermogravimetric analyses. Furthermore, biological properties of the ligand and its complexes were examined against some Gram-negative and Gram-positive bacteria and also against 2 fungi. Finally, the interaction of the ligand and its complexes with DNA was investigated by electrophoresis method.     

Study of variation in thermophysical properties of RE<Subscript>6</Subscript>UO<Subscript>12</Subscript>(s) along the lanthanide series

The novel ligand N,N,N′′′′,N′′′′-tetrabutyl-N′′′,N′′′-(N″,N″-diethyl)-ethidene bisdiglycolamide (TBEE-BisDGA) and other eight analogous extractants have been synthesized and characterized by NMR and HRMS. The solvent extraction of Th⁴⁺, UO₂ ²⁺ and Eu³⁺ from nitric acid solution using the above BisDGA extractants was investigated in 1-dodecanol at 30 ± 1 °C. The extractants exhibited higher affinity toward Th⁴⁺ than UO₂ ²⁺ and Eu³⁺ in the present system. The maximum value of separation factor SF _Th(IV)/U(VI) and SF _{Th(IV)/Eu(III)} is 78.5 and 53.3 respectively for TBEE-BisDGA, 88.1 and 69.5 respectively in the case of TB ^i-PE-BisDGA at 3 M HNO₃ solution.     

Two New Cubane-Type Tetranuclear Compounds of Copper(II), Nickel(II) Derived from Reduced Schiff Base Ligand: Syntheses,Structures and Magnetic Properties

Two tetranuclear complexes, [M(H₃L)]₄·X (1, M = Cu, X = 4,4′-dpdo; 2, M = Ni, X = DMF, H₅L = 2-[(3,5-dibromo-2-hydroxybenzyl) amino]-2-(hydroxymethyl)propane-1,3-diol, 4,4′-dpdo is 4,4′-bipyridine-N,N′-dioxide, DMF = N,N′-dimethyl formamide), have been synthesized and characterized by elemental analysis, IR and X-ray single-crystal diffraction. Compound 1 features a centrosymmetric tetranuclear copper cluster which further constructed a 1D chain through a tetra-acceptor hydrogen bonds of 4,4′-dpdo molecule. Compound 2 having a P2₁ /n space group also exhibits a tetranuclear nickel cluster with a cubane topology in which the central Ni(II) ion and oxygen atoms from H₃L^2? occupy the alternate vertices of the cube. Magnetic properties of 1 and 2 in the 2–300 K have also been discussed. The tetranuclear cubanes cores display dominant ferromagnetic interactions.     

Preparation,characterization and crystal structures of metal(II) tetraza macrocyclic complexes with organic co-ligands

The complexes [Ni(L1)(pyc)₂]·2H₂O (1) (L1 = C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane; Hpyc = pyrazinecarboxylic acid) and [Cu(L2)(H-cpdc)] (2) (L2 = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane; H₂-cpdc = cyclopropanedicarboxylic acid) have been synthesized and structurally characterized. The crystal structure of complex 1 shows a distorted octahedral coordination geometry around the nickel(II) center, with four secondary amines in the equatorial positions and two nitrogen atoms of the pyc^? ligands in the trans positions. In complex 2, the coordination environment around the copper(II) center is a Jahn–Teller distorted octahedron with four Cu–N bonds and two axial Cu–O bonds. The electronic spectra, electrochemical and TGA behavior of the complexes are significantly affected by the nature of the axial pyc^? and H-cpdc^? ligands.     

Crystal Structure of Mononuclear Non-Heme Nikel(II) Octahedral Complex: [Ni(bqenH<Subscript>2</Subscript>)(bpy)](ClO<Subscript>4</Subscript>)<Subscript>2</Subscript>·0.125H<Subscript>2</Subscript>O

The crystal structure of a mononuclear Ni(II) complex [Ni(bqenH₂)(bpy)](ClO₄)₂·0.125H₂O 1 (where bqenH₂ is N,N′-bis(8-quinolyl)ethane-1,2-diamine, bpy = 2,2′-bipyridine) is reported here. The crystallographic data for 1 are as follows: monoclinic crystal system, P2_1/n space group, a = 17.3255(11), b = 10.6110(7), c = 34.328(2) Å, α = 90°, β = 93.9480(13)°, γ = 90°, V = 6295.8(7) ų, Z = 4, d_x = 1.541 mg/m³. The nickel(II) ion coordinates four N atoms of the tetradentate ligand bqenH₂ and two N atoms of the auxiliary bidentate 2,2′-bipyridine ligand, resulting in a slightly distorted NiN6 octahedron with two perchlorates serving as charge balancing counter anions. The overall structure of 1 is stabilized by the presence of water of crystallization in the crystal lattice. The crystal structure shows two symmetrically identical octahedral NiN6 units in its asymmetric unit. The extensive hydrogen bonding network resulting in a supramolecular architecture is observed due to the N–H?O, O–H?O, O–H?Cl, and N–H?Cl interactions.     

Effect of alkali metal salts on decomposition of ionic liquid like organic salt

N ¹,N ¹,N ²,N ²-tetramethylethane-1,2-diamine-based ionic salts (TMEDA), N ¹,N ¹,N ¹,N ²,N ²,N ²-hexamethylethane-1,2-diaminium dicyanamide (HMEDA-(DCA)₂) were prepared following the quaternization and subsequent ion exchange. The chemical structure of the HMEDA-(DCA)₂ was confirmed using ¹³C NMR spectrum and elemental analysis. The corresponding viscosity of its 60 wt% solution was found to be lower than 5 cP at room temperature, which was critical for propellant application. The ignition delay of 40 wt% HMEDA-(DCA)₂ solution was decreased to 20–30 ms dramatically using alkali metal salts, Li(CH₃COO), Mg(CH₃COO)₂, and Ca(CH₃COO)₂ as a co-catalyst when white fume nitric acid was utilized as an oxidizer.     

Synthesis,structure and electrochemical properties of some thiosemicarbazone complexes of iridium

Reaction of thiosemicarbazones of salicylaldehyde and 2-hydroxyacetophenone (H₂L¹ and H₂L²) with [Ir(PPh₃)₃Cl] affords complexes of type [Ir(PPh₃)₂(L)(H)] (L = L¹ or L²) in ethanol. A similar reaction carried out in toluene affords the [Ir(PPh₃)₂(L)(H)] complexes along with complexes of type [Ir(PPh₃)₂(L)Cl], where a chloride is coordinated to iridium instead of the hydride. The structure of the [Ir(PPh₃)₂(L²)(H)] and [Ir(PPh₃)₂(L²)Cl] complexes has been determined by X-ray crystallography. Crystal data for [Ir(PPh₃)₂(L²)(H)]: space group, P2₁/c; crystal system, monoclinic; a=12.110(2) Å, b=17.983(4) Å, c=18.437(4) Å, β=103.42(3)°, Z=4; R ₁=0.0591, wR ₂=0.1107. Crystal data for [Ir(PPh₃)₂(L²)Cl]: space group, P2₁/c; crystal system, monoclinic; a=17.9374(11) Å, b=19.2570(10) Å, c=24.9135(16) Å, β=108.145(5)°, Z=4; R ₁=0.0463, wR ₂=0.0901. In all the complexes the thiosemicarbazones are coordinated to the metal center as dianionic tridentate O, N, S-donors and the two triphenylphosphines are trans. The complexes are diamagnetic (low-spin d? ⁶, S=0) and show intense MLCT transitions in the visible region. Cyclic voltammetry on all the [Ir(PPh₃)₂(L)(H)] and [Ir(PPh₃)₂(L)Cl] complexes shows a quasi-reversible Ir(III)–Ir(IV) oxidation within 0.55–0.78 V vs. SCE followed by an irreversible oxidation of the thiosemicarbazone within 0.91–1.27 V vs. SCE. An irreversible reduction of the thiosemicarbazone is also observed within ?1.10 to ?1.23 V vs. SCE.     

Dinuclear copper(II) complexes with ethylenediamine derivative and bridging oxalato ligands: solvatochromism and density functional theory studies

Two oxalato-bridged copper(II) complexes of formula, [Cu₂(L¹)₂(µ-ox)](NO₃)₂·H₂O, 1 and [Cu₂(L²)₂(µ-ox)](NO₃)₂·H₂O, 2 (ox = oxalato dianion, L¹ = N,N-dimethyl,N′-benzylethane-1,2-diamine, L² = N,N-diethyl,N′-benzylethane-1,2-diamine), have been synthesized and characterized by elemental analyses, spectroscopic (IR, UV–Vis) data and molar conductance measurements. The crystal structure of complex 1 was determined by X-ray diffraction analysis, revealing two centrosymmetric dinuclear units. The first consists of a [Cu₂(L¹)₂(µ-ox)(NO₃)₂] molecule, in which each Cu(II) center is in a square-pyramidal environment, providing two nitrogen atoms from the diamine-chelating ligands plus two oxygen atoms from the oxalate in the basal plane and an oxygen of the nitrate group in the axial position. The second unit [Cu₂(L¹)₂(µ-ox)(H₂O)₂](NO₃)₂ has a similar structure, but the apical sites are occupied by water ligands and the nitrate anions are free from coordination. Both complexes are solvatochromic. Their solvatochromism was investigated with different solvent parameter models using SPSS/PC and DFT methodology. The solvatochromic behaviors of the complexes were also explored by TD-DFT in ethanol and acetonitrile solvents. The calculated visible absorption spectra were in accord with the experimental results.     

Synthesis and structure of coordination polymer compounds of AgReO<Subscript>4</Subscript> and AgPF<Subscript>6</Subscript> with piperazine

Coordination polymers [Ag(C₄H₁₀N₂)]ReO₄ (I) and [Ag(C₄H₁₀N₂)]PF₆ (II) (C₄H₁₀N₂ is piperazine, Ppz) were synthesized and their structures were determined. Crystals of compound I are monoclinic, space group P2₁/c, a = 6.207(1) Å, b = 12.533(1) Å, c = 11.386(1) Å, β = 93.41(1)°, V = 884.2(2) ų, ρ_calc = 3.337 g/cm³, Z = 4. Crystals of II are monoclinic, space group C2/m, a = 8.723(1) Å, b = 9.083(1) Å, c = 5.797(1) Å, β = 95.07(1)°, V = 457.5(1) ų, ρ_calc = 2.548 g/cm³, Z = 2. Structure I contains polymer chains [Ag(Ppz)] _∞ ⁺ . The silver atom is linked with two nitrogen atoms of the adjacent Ppz ligands to form a nearly linear fragment; the Ag-N_av distance is 2.173 Å, and the NAgN angle is 169.4(3)°. The chains are linked with each other by weak interactions Ag…O(ReO₄) (2.643(8) Å) and N-H…O hydrogen bonds. The structure of compound II also contains cationic polymer chains [Ag(Ppz)] _∞ ⁺ . The Ag⁺ ion is located in the inversion center and has a linear coordination (Ag-N distance is 2.171(9) Å). The central P atom of the octahedral fluorophos-phate ion is also located in the inversion center; the anion is slightly distorted and has no contacts with silver ions at a distance <3.4 Å.     

Synthesis and crystal structures of tetraacetylethylenediamine and <Emphasis Type="Italic">N</Emphasis>-(2-ammoniumethyl)carbamate

Two ethylenediamine derivatives—N-(2-ammoniumethyl)carbamate HN(COO^?)CH₂CH₂N⁺H₃ (I) and tetraacetylethylenediamine (H₃CC(O))₂NCH₂CH₂N(C(O)CH₃)₂ (II) (synthesized for the first time)—have been synthesized and characterized by X-ray crystallography. Compounds I and II are isolated as minor admixtures upon an attempt to synthesize ethylenediamine complexes of lanthanum and neodymium nitrates, respectively. The crystals of I and II are monoclinic: a = 7.778 Å, b = 8.060 Å, c = 7.568 Å, β = 95.73°, Z = 4, space group P2₁/c (I); a = 5.946, b = 10.255, c = 9.343 Å, β = 95.72°, Z = 2, space group P2₁/c (II). The bond lengths and bond angles lie within the corresponding standard values. Compounds I and II have different conformations of the N-C-C-N ethylenediamine moiety: gauche in I and trans in II, and the corresponding torsion angles are equal to 66.6° and 180°, respectively.