Structural, theoretical and multinuclear NMR study of mercury(II) complexes with a new ambidentate phosphorus ylide

The reaction of the new ambidentate ylide, Ph₃PCHCOCH₂COOC₂H₅ (EAPPY), with HgX₂ (X = Cl, Br and I) in equimolar ratios using methanol as the solvent leads to binuclear complexes of the type [EAPPY·HgX₂]₂ (X = Cl (1), Br (2) and I (3)). Single crystal X-ray analysis reveals the presence of a centrosymmetric dimeric structure containing the ylide and HgX₂ (X = Br or I)_. The IR and NMR data of the product [(EAPPY)·HgCl₂]₂ (1), formed by the reaction of mercury(II) chloride with the same ylide, are similar to those of 2 and 3. Analytical data indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products. Theoretical studies indicate that the nature of the R group in ylides of the type Ph₃PCHCOR has a weak effect on the Hg-C(ylide) bond length in binuclear Hg₂L₂I₄ complexes.     

Synthesis of a new carbbenzyloxymethylenetriparatolylphosphorane ylide and study of its reaction with mercury(II) halides: Spectral and structural characterization

A new carbbenzyloxymethylenetriparatolylphosphorane ylide (BTPY), {(p-tolyl)₃PCHCOOCH₂C₆H₅},was synthesized and characterized with elemental analysis as well as various spectroscopic techniques. The reactions of the title ylide with mercury(II) chloride, mercury(II) bromide and mercury(II) iodide in equimolar ratios using dry methanol as solvent have yielded [BTPY · HgCl₂]₂ (1), [BTPY · HgBr₂]₂ (2) and [BTPY · HgI₂]₂ (3), respectively. Single crystal X-ray analysis of 2 reveals the presence of a centrosymmeteric dimeric structure containing the ylide and HgBr₂. The analytical data, IR and ¹H, ¹³C and ³¹P NMR data for the latter compound are similar to those of 1 and 3, indicating similar structures. The theoretical studies indicated that, for all three compounds, the observed trans-like structure for compound 2, is more stable than the possible cis-like structure in each case.     

Synthesis,spectroscopic and X-ray structural studies of mercury(II) halide complexes of 4-methoxybenzoylmethylenetriphenylphosphorane

The reactions of the title ylide {(C₆H₅)₃PCHCOC₆H₄OCH₃)} (MBPPY) with mercury(II) chloride and mercury(II) bromide in equimolar ratios using methanol as the solvent produces crystals of [(MBPPY) · HgCl₂]₂ (1) and [(MBPPY) · HgBr₂]₂ (2), respectively. Single crystal X-ray analyses reveal the presence of centrosymmetric dimeric structures containing the ylide and HgX₂ (X = Cl or Br) in both cases. The IR and NMR data of the product [(MBPPY) · HgI₂]₂ (3), formed by the reaction of mercury(II) iodide with the same ylide, are similar to those of 1 and 2. Analytical data indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products.     

Synthesis, Spectral and Thermal Studies of o-vanillin Oxime Complexes of Zinc(II), Cadmium(II) and Mercury(II)

Zinc(II), cadmium(II) and mercury(II) complexes of o-vanillin oxime have been synthesized and characterized by different physicochemical techniques. All the complexes have been subjected to non-isothermal decomposition studies in nitrogen atmosphere using thermogravimetry. The kinetic parameters for the decomposition of these complexes were evaluated using different methods and comparatively better results were obtained by these different methods. It has also been found that the decomposition processes of all these complexes follow first order kinetics. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis,characterization, and electrochemical study of two new macroacyclic Schiff bases and their copper(II) and zinc(II) complexes

Two new potentially octadentate N₂O₆ Schiff-base ligands 2-((E)-(2-(2-(2-((E)-2-hydroxy-3-methoxybenzylideneamino)phenoxy)phenoxy)phenylimino)methyl)-6-methoxyphenol H₂L¹ and 2-((E)-(2-(2-(2-((E)-2-hydroxy-3-methoxybenzylideneamino)phenoxy)-4-tert-butylphenoxy)phenylimino)methyl)-6-methoxyphenol H₂L² were prepared from the reaction of O-Vaniline with 1,2-bis(2′-aminophenoxy)benzene or 1,2-bis(2′-aminophenoxy)-4-t-butylbenzene, respectively. Reactions of H₂L¹ and H₂L² with copper(II) and zinc(II) salts in methanol in the presence of N(Et)₃ gave neutral [CuL¹]?·?0.5CH₂Cl₂, [CuL²], [ZnL¹]?·?0.5CH₂Cl₂, and [ZnL²] complexes. The complexes were characterized by IR spectra, elemental analysis, magnetic susceptibility, ESI–MS spectra, molar conductance (Λ_m), UV-Vis spectra and, in the case of [ZnL¹]?·?0.5CH₂Cl₂ and [ZnL²], with ¹H- and ¹³C-NMR. The crystal structure of [ZnL¹]?·?0.5CH₂Cl₂ has also been determined showing the metal ion in a highly distorted trigonal bipyramidal geometry. The electrochemical behavior of H₂L² and its Cu(II) complex, [CuL²], was studied and the formation constant of [CuL²] was evaluated using cyclic voltammetry. The logarithm value of formation constant of [CuL²] is 21.9.     

New mercury(II) and cadmium(II) complexes with (p-methylbenzoyl)methylene triphenylphosphorane: Synthesis,spectroscopic and structural characterization

Reaction of Ph₃PCHCOC₆H₄Me (L), with HgX₂ and CdCl₂·H₂O in methanol with equimolar ratios give binuclear complexes of the type [MX(μ-X){CH(PPh₃)C(O)C₆H₄Me}]₂ (M = Hg; X = Cl (1), Br (2), I (3), M = Cd; Cl(4)). The bridge-splitting reaction of binuclear complexes [MX(μ-X){CH(PPh₃)C(O)C₆H₄Me}]₂ by dimethyl sulfoxide (DMSO) yields the mononuclear complexes [MX₂{CH(PPh₃)C(O)C₆H₄Me}(OSMe₂)] (M = Hg; X = Cl (5), Br (6), I (7), M = Cd; Cl (8)). The characterization of these complexes was carried out by elemental analysis and FT-IR, ¹H, ³¹P, and ¹³C NMR spectroscopies. C-coordination of ylide and O-coordination of DMSO are demonstrated by single-crystal X-ray analysis of mononuclear complex of [HgBr₂{CH(PPh₃)C(O)C₆H₄Me}(OSMe₂)] (6). Complex 6 is monomeric with tetrahedral geometry around the metal ion.     

Synthesis and crystal structure of some new cadmium (II) macrocyclic Schiff-base complexes containing piperazine moiety

The metal templated Cd(II) cyclocondensation of 2,6-diacetylpiridine or 2,6-pyridinedicarbaldehyde and two different amines containing piperazine moieties have been investigated. The resulting ligands, L¹ and L² are 16- and L³ and L⁴ 17-membered pentaaza macrocycles. The complexes have been characterized by a variety of methods including IR, ¹H, ¹³C NMR, DEPT, COSY(H,H), HMQC(H,C), FAB spectrometry and conductivimetry measurements. The crystal structures of [CdL²Cl](CH₃OH)ClO₄ (2) and [CdL⁴(NO₃)(H₂O)]ClO₄ (4) have been also determined, and it was shown that the geometry of the Cd(II) ion in the complexes is slightly distorted pentagonal pyramidal and pentagonal bipyramidal, respectively. The gas-phase structures of ligands, L² and L⁴ and their Cd(II) complexes have also theoretically studied.     

Synthesis,spectroscopic, structural characterization of Cd(II) and Zn(II) complexes based on the N-methyl-C-(2-pyridyl)nitrone

Zinc and cadmium complexes, ML₂(NO₃)₂ (L = N-methyl-C-(2-pyridyl)nitrone) were synthesized and characterized by means of X-ray diffraction crystallography and IR and NMR spectroscopy. The organic ligands in the complexes are coordinated via the oxygen atom of the nitrone group and the nitrogen atom of the pyridine moiety. The coordination environment of the central atoms is a distorted octahedron. The bond lengths and angles of the complexes were calculated using the DFT method with B3LYP functional. Theoretical studies revealed that the geometric parameters are in agreement with the experimental data. The fluorescent properties for the zinc and cadmium complexes were investigated at room temperature.     

Synthesis of New Phosphonium Ylides Containing Thiophene and Furan Rings and Study of Their Reaction with Mercury(II) Halides: Spectral and Structural Characterization

Reactions of phosphonium ylides (4‐MeC₆H₄)₃PCHC(?O)(2‐C₄H₃S) (tptpy), Ph₃PCHC(?O)(2‐C₄H₃O) (fppy), and (4‐MeC₆H₄)₃PCHC(?O)(4‐BrC₆H₄) (bbtppy) with HgX₂ (X=Cl, Br, and I) in equimolar ratios in MeOH as solvent leads to the binuclear products 1 – 3 (Scheme 1). The bridge‐splitting reaction of the binuclear complex [{HgI₂(bbtppy)}₂] ( 3c ) by DMSO yields the mononuclear complex [HgI₂?(bbtppy) (DMSO)] ( 3d ) (Scheme 2). This bridge‐splitting reaction can also be a method for the synthesis of mononuclear products. C‐Coordination of the ylide and O‐coordination of DMSO are demonstrated by a single‐crystal X‐ray‐analysis of the mononuclear complex 3d . Characterization of the obtained compounds was also performed by means of elemental analysis and IR and ¹H‐, ³¹P‐, and ¹³C‐NMR spectroscopy. A theoretical study of some Hg^II complexes with phosphonium ylides is also reported.     

大环金属铜(II)、镍(II)配合物的模板合成与晶体结构

用模板法合成了1个大环金属铜(II)配合物[CuLCl₂]·3H₂O (1)和3个大环金属镍(II)配合物[NiLCl₂] (2)，[NiL](ClO₄)₂ (3)和[NiLH₂](ClO₄)₄ (4)(L=3,10-二乙基-1，3，5，8，10，12-六氮杂十四烷)，通过X-射线衍射单晶结构分析测定了它们的晶体结构。晶体结构显示：配合物1和2的金属离子与大环配体的4个氮原子及大环平面轴向的2个氯离子以八面体配位方式配位；配合物3和4的金属离子与大环配体的4个氮原子以平面正方形配位方式配位，配合物4的侧链氮原子的质子化导致侧链结构翻转，使得其侧链与大环平面共面。     

Structures of Nickel(II) and Copper(II) Complexes of 14-Membered Macrocyclic Quadridentate Ligands

The structures of 41 Ni(II) and 17 Cu(II) complexes of macrocyclic quadridentate ligands have been analyzed, and are discussed about bond lengths, bond angles, conformations, and configurations, upon which many conclusions are formed. The inter- or intra-molecular hydrogen bonds exist among ligands and hydrates in many compounds and play an important role in the structures. There are exhibited two distinct peaks on the histogram of the average Ni-N distances, corresponding to four coordination and six coordination; these average Ni-N distances are 1.95(4) Å and 2.10(5) Å, respectively. The most probable structures of Ni(II) macrocyclic compounds have coordination number six for the metal ion, chair forms for six-membered rings, planar structure for the metal ion and the four donor atoms of the quadridentate ligand and an inversion center at the central metal ion.     

Synthesis and characterization of two new asymmetrical branched amines and related Mn(II) and Ni(II) Schiff base complexes containing pyridine moieties: Crystal structures of Mn(II) and Ni(II) complexes and their antibacterial properties

Two new branched pentadentate amines (N₅), 3,7-bis(2-pyridylmethyl)-5,5-dimethyl-3,7-diazaheptane-1-amine (1) and 4,8-bis(2-pyridylmethyl)-6,6-dimethyl-4,8-diaza octane-1-amine (2) have been prepared. These have been used to synthesis two new Schiff base complexes containing a pyridine and 2-pyridylmethyl pendant arm, by template [1+1] condensation of pyridine-2-carbaldehyde with the amines in the presence of Mn(II) in methanol. Elemental and spectral results are used to characterize the complexes and their structures are confirmed by single crystal X-ray diffraction studies. The structure of MnL¹(ClO₄)₂ indicates that in the solid state the Mn(II) ion adopts a slightly distorted octahedral geometry. The crystal structure of [Ni(1)(MeCN)](ClO₄)₂ is also reported and exhibits a slightly distorted octahedral geometry. Also the synthesized complexes were screened for their antibacterial activity against Escherichia coli (Lio), Serratia marcescens (PTCC 1330), Staphylococcous aureus (ATCC 6633), and Proteus vulgaris (Lio) and results showed that the all complexes have antibacterial effects and [NiL¹](ClO₄)₂, [MnL²](ClO₄) and [MnL¹](ClO₄)₂ have more effective ones against E. coli.     

The crystal structures and electrochemical studies of two naphthalenic Schiff base copper(II) complexes

The Schiff base ligands, 2-hydroxy-N-cyclohexyl-l-naphthaldimine (I), and 3-hydroxy-N-cyclohexyl-2-naphthaldimine (II), and their corresponding Cu^II complexes (1–2) respectively were synthesized and characterized. The crystal and molecular structures of bis-{(cyclohexyl)[(2-oxo-1H-naphth-1-ylidene)-methyl]aminato}copper(II) (1) and bis-{(cyclohexyl)[(3-oxo-2H-naphth-2-ylidene)-methyl]aminato} copper(II) (2), were determined. The X-ray diffraction study shows that the geometry around the metal atom for (1), is stepped square planar with a step of 1.063 Å while for (2), the geometry around the metal atom for square planar with an angle between the coordination planes O(1)---Cu---N(1) and O(1a)---Cu---N(1a) of 39.9°. Electrochemical studies show a dependence of the Cu^II/Cu^I potentials on the ligand structure.     

Copper(II) Complexes with Chiral Diaminodiamido Ligands: Solution and Structural Studies

Abstract

Three diaminodiamido ligands (S,S)-N,N′-bis(prolyl)ethanediamine (ProNN-2), (S,S)-N,N′-bis(N-methylvalyl)ethanediamine (Me₂ValNN-2), and (S,S)-N,N′-bis(N-methylphenylalanyl)-ethanediamine (Me₂PheNN-2) were synthesised and their complex formation equilibria with copper(II) investigated in aqueous solution by potentiometry and, for ProNN-2, by electronic spectrophotometry. ProNN-2 forms the species [CuLH]³⁺, [Cu₂L₂]⁴⁺, [Cu₂L₂H_?2]²⁺ and [CuLH_?2], Me₂PheNN-2 forms the complexes [CuLH]³⁺, [Cu₂L₂H_?2]²⁺ and [CuLH_?2], whereas Me₂ValNN-2 forms the monomer [CuLH_?1]⁺ but not the dimer. The dimeric cation [Cu₂L₂H_?2]²⁺, of Me₂PheNN-2 has severe steric requirements, as demonstrated by the X-ray crystal structure of the complex [Cu₂L₂H_?2]Cl₂· 12H₂O, of the corresponding non-methylated ligand. Since copper(II) complexes of the ligands examined are used as additives to the mobile phase to perform chiral resolution of D,L-amino acids in RP-HPLC, the present results provide valuable clues to an understanding of the mechanism of the enantiomeric separation.     

Mercury(II) complexes of stabilized phosphine-phosphonium ylide derived from bis(diphenylphosphino)methane: Synthesis, spectra and crystal structures

The reaction of a mixed phosphine-phosphonium ylide, PPh₂CH₂PPh₂C(H)C(O)Ph with mercury(II) halides in methanol under mild conditions yielded the P, C-chelated complexes, [HgX₂(PPh₂CH₂PPh₂C(H)C(O)Ph)] where X = Cl (2), Br (3), I (4). Single crystal X-ray diffraction studies reveal the presence of mononuclear complexes containing Hg atom in a distorted tetrahedral environment and long Hg-C_ylide bond. The five-membered chelate rings in the two independent molecules present in the asymmetric unit of 4 adopt ‘envelope’ and ‘twist’ conformations. Spectroscopic studies also indicate the weaker Hg-C bonding. Additionally, the molecular structure of the free ylide (1) is also discussed.     

DTPA-BpABA与锰配合物的结构表征和弛豫研究

X-ray single crystal analysis of a new paramagnetic manganese（Ⅱ） complex with DTPA-BpABA （a DTPAbisamide derivative）, Mn（DTPA-BpABA）·4H2O, shows that four oxygen atoms and three nitrogen atoms from the ligand coordinate to Mn（Ⅱ） cation, forming a seven-coordinate distorted pentagonal bipyramid polyhedron. In the crystal, the carboxyl groups and the nitrogen atoms extensively form hydrogen bonds with the lattice water molecules, building a 3D-network. The relaxometric study indicates that the R1 value of the paramagnetic manganese（Ⅱ）complex is 5.12 mmol·L·s^-1. The higher R1 value means that this complex may find an application in magnetic resonance imaging （MRI） technique.     

含四氮杂大环的双(O,O''''-二(2-苯乙基)二硫代磷酸根)合镍(II)或铜(II)配合物的合成和晶体结构

合成了含四氮杂大环hmta(hmta = meso-5,7,7,12,14,14-六甲基-1,4,8,11-四氮杂环十四烷 )和O,O-二(2-苯乙基)二硫代磷酸根的配合物 [Ni(hmta){SSP(OCH2CH2Ph)2}2] 1和 [Cu(hmta){SSP(OCH2CH2Ph)2}2] 2 , 并测定了它们的晶体结构。配合物1属单斜晶系,空间群为P21/c,晶胞参数为: C48H72N4O4P2S4Ni, a = 9.827(3), b = 19.430(6), c = 13.932(3) ? b = 99.99(2), Mr = 1017.99, V = 2620(1) 3, Z = 2, Dc = 1.285 g/cm3, = 0.635 mm-1, F(000) = 1076, 最终的偏离因子为R = 0.0434, wR = 0.1078, 相应的可观测反射数为2306; 配合物2属单斜晶系, 空间群为P21/c, 晶胞参数为: C48H72N4O4P2S4CuO25, a = 9.730(4), b = 19.513(4), c = 14.031(3) ? b = 99.97(3), Mr = 1022.82, V = 2624 (1) 3, Z = 2, Dc = 1.295 g/cm3, = 0.681 mm-1, F(000) = 1086, 最终的偏离因子为R = 0.0465, wR = 0.1222, 相应的可观测反射数为2492。结构测定表明:两配合物中的配体 (PhCH2CH2O)2PS2-均为单齿配体,金属离子与硫和氮形成了六配位的拉长的八面体配合物,配合物分子具有中心对称性; 同时晶胞中配合物的两配体之间形成了2种N-H贩稴氢键。     

2-甲基-5-(2-吡啶基)-1,3,4-噁二唑Cu(II),Cd(II)配合物的合成,晶体结构和表征

以2-甲基-5-（2-吡啶基）-1,3,4-噁二唑（L）为配体合成了[Cu₂L₂（μ-Cl）₂Cl₂]（1）和[CdL₂（NO₃）₂]（2）,测定了X射线单晶结构,用红外光谱、紫外光谱、荧光及热重分析进行了表征。配体L和配合物2属于单斜晶系,配合物1属于三斜晶系。L,1和2的空间群分别为P2₁/c,P1和C2/c。配合物1是通过2个氯原子（Cl1,Cl1ⁱ）桥联形成的双桥双核Cu(II)配合物,具有畸变四方锥构型[CuCl₃N₂]。配合物2具有畸变八面体构型[CdN₄O₂]。     

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     

Spectral and structural studies of Ni(II) and Zn(II) complexes of N-trans-cinnamylidene-2-mercaptoaniline

Ni(II) and Zn(II) complexes of the bidentate thiol ligand N-trans-cinnamylidene-2-mercaptoaniline which is obtained from trans-cinnamaldehyde and 2-mercaptoaniline were prepared and characterized by their IR absorption spectra, X-ray powder diffraction measurements, elemental analysis and ¹H-NMR spectra. On the other hand, energy minimization studies of the molecules were carried out to obtain the most probable three-dimensional molecular conformations.The comparative ¹H-NMR, IR, X-ray powder diffraction and energy minimization studies have shown that metal atoms are connected to the N and S atoms of Schiff bases and the complex have cis type fashion.