X-Ray Diffraction and Raman Spectroscopic Study of Bis-(Pyridine Base) Complexes of Cadmium(II) Halogenides

Summary.  The molecular structures of bis-(pyridine base) complexes of cadmium(II) chloride and bromide, where the pyridine base is pyridine ( py), 3-methylpyridine (3-Me-py), 4-methylpyridine (4-Me-py), and 4-ethylpyridine (4-Et-py), were investigated by means of single-crystal X-ray diffraction and Raman spectroscopy. The crystal structures of CdCl₂ py ₂ (1), CdCl₂(3-Me-py)₂ (2), and CdCl₂(4-Me-py)₂ (3) were determined. All crystals are monoclinic; 1: a = 17.784(2), b = 8.666(1), c = 3.8252(7) ?, β = 91.54(1)°, space group: P2₁/n; 2: a = 11.89(1), b = 14.41(1), c = 3.874(6) ?, β = 92.3(1)°, space group: P2₁/a; 3: a = 21.091(2), b = 3.8884(5), c = 18.2317(3) ?, β = 113.64(1)°, space group: C2/c. The structures were refined to R/R _w values (%) of 3.2/5.5, 3.0/5.0, and 3.4/5.1 for 1–3. All cadmium atoms are octahedrally coordinated with the chloride ions forming infinite di-μ-chloro polymeric linear chains and the nitrogen atoms of the pyridine base in trans configuration. The Cd chains are oriented along the c-axis in 1 and 2 and along the b-axis in 3. The crystal structures indicate the absence of a peculiar interaction between the polymeric chains. The Raman spectra of eight complexes were measured in the range of 550–50 cm⁻¹, and the Raman peaks originating from cadmium-halogen vibrations were assigned. The Raman spectra of 1 and 2 are quite alike in the lattice mode vibration region. The resemblance of the cadmium-halogen vibration peaks indicates the same halogenide ion bridged octahedral structure for all complexes. Received March 27, 2001. Accepted (revised) June 19, 2001     

Bis -( bis -(1,3-diaminopropane)-copper(II) Tetracyanonickellate(II)) Tetrahydrate: Preparation, Characterization, and Crystal Structure of a Novel Molecular Tetracyanonickellate

 [Cu(tn)₂Ni(CN)₄]₂ċ4H₂O and Cu(tn)₂Ni(CN)₄ (tn = 1,3-diaminopropane) were prepared and characterized. The hydrate is unstable on air and readily dehydrates to Cu(tn)₂Ni(CN)₄. Crystal structure analysis of the hydrate at 150 K revealed a novel tetranuclear molecular structure of the tetracyanonickellate. The building elements are two [Cu(tn)₂]²⁺ cations (coordination numbers of Cu: 5 and 6, respectively), two [Ni(CN)₄)²⁻ anions, and crystal water. The two cations are linked by one tetracyanonickellate anion via bridging cyano groups placed in cis positions. The second anion is bound weakly (Cu-N = 2.82 ?) via one μ₂-bridging cyano ligand. The tetranuclear molecules and pairs of solvate water molecules are linked by strong hydrogen bonds, thus forming infinite planes which are linked in the third dimension by considerably weaker hydrogen bonds.     

Formation of Zinc(II) and Cadmium(II) Complexes with Pyridine Oxime Ligands in Aqueous Solution

Complex formation equilibria involving pyridine-2-carboxaldehyde oxime (1), 1-(2-pyridinyl)ethanone oxime (2) and 6-methylpyridine-2-carboxaldehyde oxime (3), HL, with zinc(II) and cadmium(II) ions were studied in aqueous 0.1 M NaCl solution at 25° C by potentiometric titrations with a glass electrode. Experimental data were analysed with the least-squares computer program SUPERQUAD to determine the complexes formed and their stability constants. With Ligands 1 and 2 the sets of complexes for Zn(II) and Cd(II) are essentially the same, mono- and dinuclear oxime complexes and their deprotonated/hydrolysed products H_pM_q(HL)^2q+p _r. Owing to the steric requirements of the 6-methyl group, sets of complexes formed with 3 are distinctly different. For zinc(II), only dinuclear oximato species H_pZn₂(HL)^4q+p ₂ ( p = ? 2, ? 3, ? 4) are found, while for the larger cadmium(II) ion mononuclear oximato species CdL⁺ and CdL₂ are detected in addition to the dinuclear complex H_pCd₂(HL)^4q+p ₂ ( p = ? 3).     

Crystal Structure of Bis -(2,2′-bipyridine-N,N′)-(dicyanamide-N)-copper(II) Tricyanomethanide. Electronic and Structural Parameters Describing the Shape of Coordination Polyhedra in Five-Coordinated Copper(II) Compounds

 The structure of the new compound [Cu(bpy)₂N(CN)₂]C(CN)₃ (6) is compared with thestructures of six copper(II) coordination compounds with phenanthroline or bipyridine ligands and N-donor pseudohalide anions: [Cu(phen)₂NCS]C(CN)₃ (1), [Cu(bpy)₂NCS]C(CN)₃ (2), [Cu(phen)₂NCS]ONC(CN)₂ (3), [Cu(phen)₂N(CN)₂]C(CN)₃ (4), [Cu(bpy)₂C(CN)₃]C(CN)₃ (5), and [Cu(bpy)₂NCO]C(CN)₃ (7). The Cu(II) atoms in all above compounds are five-coordinated with an N-donor atom of the pseudohalide anion located in the equatorial plane of a deformed trigonal bipyramid. The shape of the coordination polyhedra and the degree of trigonal bipyramidal distortion towards a tetragonal pyramid are discussed and described using one electronic and several structural criteria which are discussed and compared.     

X-Ray Diffraction Study on Manganese(II) Complexes with Thiophene-2-Carboxylate and Furan-3-Carboxylate Ligands

Abstract

Mn(II) cations in the crystals of trisaquobis(μ-thiophen-2-carboxylato-O,O′)(thiophen-2-carboxylato-O)manganese(II) monohydrate are bridged by oxygen atoms donated by bidentate carboxylic groups of two thiophen-2-carboxylate ligands. In addition, each Mn(II) ion is coordinated by an oxygen atom of a monodentate carboxylic group of this ligand and three oxygen atoms of water molecules. The coordination around the Mn(II) cation is octahedral. The bridging of the ligands results in molecular ribbons propagating in the c-direction of the crystal held together by C?H…O hydrogen bonds. The crystal structure of diaquobis(μ-furan-3-carboxylato-O,O′)di(μ-furan-3-carboxylato-O,O)(μ-aqua-O)manganese(II) consists of dinuclear structural units. In each molecule Mn(II) cations are O,O′ bridged by oxygen atoms of bidentate carboxylic groups of two furan-3-carboxylate ligands and have a water located between the Mn cations. The units are O,O′ bridged to Mn(II) ions located in adjacent units by bidentate oxygen atoms, forming molecular ribbons extending in the c-direction. Octahedral coordination around each Mn(II) ion is completed by two water molecules. The octahedra around two adjacent metal ions in the unit share a common apex - the bridging oxygen atom of the water molecule. The ribbons are held together by C?H…O hydrogen bonds between furan ring oxygen atoms and the carbon atoms of adjacent furan rings.     

Schiff碱Cu(II)配合物的结构、光谱及电化学性质

为了探讨配合物结构对性质的影响,合成了两个Schiff碱的铜配合物{[Cu(II) (L1)]ClO_4(1)和[Cu(II)(L2)-(H_2O)_2](BF_4)_2(2)},并用红外、质谱和元素分 析对它们进行了表征,用X射线衍射方法测定了它们的昌体结构。实验结果表明： 配合物1和2均属三斜晶系,P1空间群。1的晶胞参数为a = 1.1147(6)nm, b = 1. 1481(7)nm, c = 0.770(3)nm; α = 98.81(4) °,β=106.94(4)°γ= 66.49(4)° ;V=0.8715(8)nm~3,Z=2,R=0.044.2的晶胞参数为a=1.0819(4)nm, b = 1.4095(6) nm, c = 1.0192(4)nm; α=96.54(4)°,β=106.18(3)°,γ=80.51(3)°;V=1. 4681(5)nm~3, Z=2, R = 0.068.此外,配合物1的Cu-O(1)键长[0.1880(5)nm]和可 见吸收波长(λ_(max)=557nm)比2[0.1982(6)nm,λ_(max)=605nm]短。配合物2在- 0。80～-1.20V范围内出现两个氧化和两个还原过程。     

Stereochemistry from X-Ray Diffraction Studies of Three Palladium(II) Complexes with Terdentate Chelating Amines

X-ray crystal structure analysis of three Pd(II) complexes with cis-3,5-diaminopiperidine (DAPI) shows that the metal ion has a square planar coordination. The DAPI groups are trans in the protonated and mixed complexes. Most surprisingly, the unprotonated complex has a basket-like structure with the DAPI groups cis.     

Blue Luminescent Zinc(II)-and Cadmium(II)-1,4-phenylenediacetate Complexes

1 INTRODUCTION The crystal engineering and design of solid-state coordination polymers have become a very attrac- tive field in recent years[1～4]. Many interesting fra- meworks with intriguing potential applications have been obtained through the self-assembly of selected metal centers and carboxylate ligands[5, 6]. Compared with aromatic carboxylate ligands such as terephtha- lic acid[7, 8], benzene tricarboxylic acid[9, 10], benzene tetracarboxylic acid[11, 12] and so on, those ligands …     

The Unusual Thermodynamic Stability Order of the First-series Transition Metal Complexes with N,N,N′-tri(2-pyridylmethyl)glycinamide and the Crystal Structure of the Nickel(II) Complex

A new pentadentate tripodal peptide ligand N,N,N′-tri(2-pyridylmethyl)glycinamide (L) has been synthesized. The crystal structure of its nickel(II) complex, [NiL(H₂O)] · 1.17ClO₄ · 0.17H₃O · 0.03H₂O (1), has been determined by X-ray diffraction. In the complex, the deprotonated ligand L acts in a pentadentate fashion and coordinates to the nickel(II) ion through five nitrogen atoms, while the sixth position is occupied by a water molecule. The units of the complex are connected as a 3D honeycomb network by intermolecular hydrogen bonds. The thermodynamic properties of the ligand L with the first-series transition metal ions Co(II), Ni(II), Cu(II) and Zn(II) have been investigated by potentiometric titration and the results show that the order of their stability constants does not conform to the Irving–Williams serial. The reason why the stability constants of the Cu(II) complex are unconventionally small is proposed.     

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 .     

Synthesis and structural studies of (2 E ,3 E ,6 R ,9 E ,11 E )-6-isopropenyl-3,6,10-trimethyl-5,8-dioxa-4,9-diazadodeca-3,9-diene-2,11-dione dioxime, ligand and its Mono-, homo, and heterodinuclear copper(II)/nickel(II) complexes

This article describes the synthesis of a new (2E,3E,6R,9E,11E)-6-isopropenyl-3,6,10-trimethyl-5,8-dioxa-4,9-diazadodeca-3,9-diene-2,11-dione dioxime (H₂hmdm), and its mono-, homo, and heterodinuclear copper(II)/nickel(II) complexes. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). The Cu(H₂hmdm), molecule coordinates to the second copper(II) ion through the oximate oxygens to afford a binuclear structure doubly bridged by the oximate groups in the cis arrangement. In the dinuclear complexes, in which the first Cu^II ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu^II ion is ligated with the 1,10-phenanthroline nitrogen atoms. Ligand and its mononuclear copper(II), homo and heterodinuclear copper(II)–nickel(II) complexes of (H₂hmdm) were characterized by elemental analyses, magnetic moments, ¹H-n.m.r. and ¹³C-n.m.r., i.r., and mass spectral studies. The data support the proposed structure of H₂hmdm and its complexes.     

New Saccharinato/Ammonia Complexes of Nickel(II) and Zinc(II). A Structural and Spectroscopic Study

Two new saccharinate/NH₃ complexes of composition [Ni(sac)₂(NH₃)₄] and [Zn(sac)₂(NH₃)₂] were obtained and their crystal structures determined by single crystal X‐ray diffractometry. The elongated octahedral Ni^II complex crystallizes in the monoclinic P2₁/c space group with Z = 2 whereas the tetrahedral Zn^II complex is triclinic (space group and Z = 2). For [Ni(sac)₂(NH₃)₄] the magnetic moment and electron absorption spectrum were obtained and discussed. The infrared spectra of both complexes were also recorded and briefly commented.     

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 .     

Structural and Spectroscopic Characterization of Iron(III) Dioxoporphodimethene Complexes and Their Autoreduction to an Iron(II) Complex in Pyridine

Three iron complexes of the meso-dioxo derivative of octaethylporphryin (trans-H(2)OEPO(2)) were characterized by X-ray diffraction. Green ClFe(III)(trans-OEPO(2)).1.5C(6)H(6) crystallizes in the monoclinic space group P2(1)/c with a = 13.766(3) ?, b = 19.075(3) ?, c = 15.217(3) ?, beta = 99.87(2) degrees at 123 K with Z = 4. Refinement of 2712 reflections with F > 6.0sigma(F) and 223 parameters yielded R = 0.0624, R(w) = 0.0596. The iron complex contains a domed dioxoporphodimethene macrocyclic ligand. The observation of a five-coordinate iron(III) ion with an axial Fe-Cl distance of 2.232(2) ? and in-plane Fe-N distances averaging 2.082 ? is consistent with its high-spin (S = (5)/(2)) character. This monomer is readily converted to the green {Fe(III)(trans-OEPO(2))}(2)O using aqueous hydroxide. {Fe(III)(trans-OEPO(2))}(2)O crystallizes in the monoclinic space group C2/c with a = 23.541(8) ?, b = 15.392(5) ?, c = 18.686(8) ?, and beta = 90.09(3) degrees at 294 K with Z = 8. Refinement of 3472 reflections with F > 6.0sigma(F) and 393 parameters yielded R = 0.0484, R(w) = 0.0527. The complex possesses a crystallographically imposed 2-fold symmetry axis that passes through the oxo ligand. The dioxoporphodimethene ligands within the molecule are roof-shaped and fold away from each other. The axial Fe-O distance is 1.749(1) ? with longer in-plane Fe-N distances (average 2.077 ?). The Fe-O-Fe angle of 165.4(2) degrees deviates significantly from linearity and is more acute than related porphyrin complexes. Pyridine solutions of either the iron(III) monomer or &mgr;-oxo dimer autoreduce over a period of days to give (py)(2)Fe(II)(trans-OEPO(2)). This red compound crystallizes in the space group P2(1) with a = 19.177(4) ?, b = 20.039(4) ?, c = 10.547(2) ?, and beta = 100.36(3) degrees at 130 K with Z = 2. Refinement of 5090 reflections with one restraint and 984 parameters yielded R1 = 0.0684, wR2 = 0.1763. The complex crystallizes with two distinct molecules in the asymmetric unit; each molecule contains a different degree of disorder with respect to the trans meso oxygen atoms (50/50, 71/29). Each independent molecule exhibits severe ruffling of the macrocycle. The six coordinate iron(II) center is diamagnetic. The axial Fe-N(pyridine) distances average 1.98 ?, and the in-plane Fe-N(pyrrole) distances average 1.95 ?. A common trend observed for the dioxoporphodimethene macrocycle in all of these structures is an elongation toward the trans oxidized meso carbons. These complexes were originally prepared as cis and trans isomeric mixtures that can be enriched in the trans isomer by fractional crystallization. This is evident in their distinctive (1)H NMR spectra. In addition, these compounds are characterized by electron impact mass spectrometry and UV-visible, ESR, and infrared spectroscopies.     

Complexes of Copper(II) Chloroacetates with Pyridine and Picoline N-Oxides

1:1 Adducts of composition Cu(CH_3-xCl_xCOO)₄L and 1:2 adducts of composition Cu(CH_3-xCl_xCOO)₂L₂ where x=1-3 and L is pyridine N-Oxide (PyNO), 2-picoline N-oxide (2-PicNO) or 3-picoline N-oxide (3-PicNO) have been isolated by the interaction of copper(II) chloroacetates with the appropriate N-oxide ligands. The adducts are soluble in methanol.     

Synthesis and X-Ray Diffraction Study of 2-(2-Acyl-1-phenylethenyl)pyrroles

Pyrroles add to 2-acyl-1-phenylacetylenes on the surface of silicon dioxide at 20-90°C affording structurally stable Z-isomers of 2-(2-acyl-1-phenylethenyl)pyrroles containing a strong intramolecular hydrogen bond. The geometry of these molecules was established by X-ray diffraction analysis of a single crystal of 2-(2-benzoyl-1-phenylethenyl)-4,5,6,7-tetrahydroindole.     

Synthesis,Spectroscopic, and Structural Properties of Organogermanyl(IV) Complexes of Pyridine Oximes

Abstract

Reactions of triorganogermanyl(IV) chlorides and diorganogermanyl(IV) dichlorides with sodium salts of pyridine-2-carbaldehyde oxime and 2-acetylpyridine oxime, respectively, in 1:1 and 1:2 molar ratio produced organogermanyl(IV) oximates. All the derivatives have been characterized by spectroscopic techniques and tetrahedral structures have been proposed on the basis of spectroscopic data and molecular orbital calculations.