Complexes of pendant-armed cyclam derivatives with copper(II) perchlorate: Synthesis and crystal structures

A designed series of cyclam type macrocyclic ligands 1–3 that feature a different degree of saturation and number of functional appendages of the macroring, including preparation of the respective Cu(II) perchlorate complexes 1a–3a, was synthesized. Comparative discussion of the X-ray crystal structures of the free ligands and the corresponding complexes shows that dependent on the structure of the compound, transanular, pendant arm and anion involving conventional and weaker H bond contacts are operating. In the complexes, the coordination environment around the Cu(II) cation is distorted octahedral with the nitrogens of the macroring defining the equatorial sites and either two oxygens, each of a perchlorate anion, or the lateral pyridine nitrogens in apical positions. Thus, only the pyridine containing pendants in 3a proved effective in metal ion coordination while the anisyl groups are engaged in H bonding, respectively. The uncomplexed macrocycle 3 yielded an inclusion compound with chloroform, also indicating a special ability relating to this series of compounds.     

Synthesis, characterization, and X-ray crystal structures of cyclam derivatives. 5. Copper(II) binding studies of a pyridine-strapped 5,12-dioxocyclam-based macrobicycle

The copper(II) binding properties of the macrobicyclic diamide 1,9,12,18,22-pentaazatricyclo[7.6.6.1(3,7)]docosa-3,5,7(22)-triene-13,19-dione (L1) have been fully investigated by spectroscopic (IR, UV-vis, EPR, MALDI-TOF MS), X-ray diffraction, potentiometric, electrochemical, and spectroelectrochemical methods. This constrained receptor possesses a hemispherical cavity created by cross-bridging the 1 and 8 positions of trans-dioxocyclam (1,4,8,11-tetraazacyclotetradecane-5,12-dione, L2) with a 2,6-pyridyl strap. Treatment of L1 with a copper salt in methanol produces a red complex of [Cu(L1H(-1))]+ formula in which the copper atom is embedded in a 13-membered ring and coordinated by both amines as well as the pyridine and one deprotonated amide nitrogen atoms. Infrared spectroscopy provides evidence for protonation of the carbonyl oxygen atom belonging to the copper-bound amide of [Cu(L1H(-1))]+ under strongly acidic conditions. The resulting conversion of the amidate into an iminol group highlights the inert character of the corresponding complexes, which do not dissociate at low pH values. In contrast, both secondary amides of L1 deprotonate in the presence of a weak base, thus affording a blue pentacoordinated [Cu(L1H(-2))] compound where the copper atom sits in the center of the 14-membered dioxocyclam fragment. In aqueous solution, both complexes undergo a pH-driven (pK(a) = 8.73(2)) molecular reorganization, which is reminiscent of a glider motion. The copper(II) cation switches rapidly and reversibly from a four-coordinate flattened tetrahedral arrangement of the donor atoms in the red species to a five-coordinate environment in the blue species, which is intermediate between a square pyramid and a trigonal bipyramid. Conversion of the red to the blue form was also demonstrated to occur upon reduction of [Cu(L1H(-1))]+ by cyclic voltammetry (E(pc) = -0.64 V/SCE in CH(3)CN).     

Synthesis and crystal structures of two new lead(II) hexafluoroarsenates(V)

In the system PbF₂/AsF₅/anhydrous hydrogen fluoride (aHF) two new lead(II) hexafluoroarsenates(V) Pb(HF)(AsF₆)₂ and PbFAsF₆ were isolated. Pb(HF)(AsF₆)₂ is formed when the molar ratio AsF₅:PbF₂ is 2 or higher. It crystallizes in the space group Pbcn with a=1058.3(3) pm, b=1520.9(6) pm, c=1079.4(3) pm, V=1.7374(10) nm³ and Z=8. The HF molecule is directly connected to the Pb center, eight fluorine atoms from three different AsF₆⁻ ions (Pb–F distances ranging from 248(4) to 276(2) pm) and one further fluorine at 306(3) pm complete the coordination sphere. PbFAsF₆ is obtained when equimolar amounts of PbF₂ and AsF₅ react in aHF. PbFAsF₆ crystallizes in the space group P with: a=466.10(10) pm, b=723.70(10) pm, c=747.40(10) pm, =105.930(10)°, β=101.49(2)°, γ=90.660(10)°, V=0.23698(7) nm³ and Z=2. The basic unit in the structure of PbF(AsF₆) consists of a four-membered ring of two Pb and two F atoms. The Pb atoms in the ring are further connected by two AsF₆⁻ units via cis-fluorine bridges, thus forming a [PbF(AsF₆)]₂ cluster, which interacts by additional Pb–F bonds thus forming a ribbon-like polymer.     

Syntheses,characterization and x-ray crystal structures of copper(II) and nickel(II) complexes of tridentate monocondensed diamines

The syntheses and characterization of three compounds involving tridentate “half-units” 7-amino-4-methyl-5-aza-3-hepten-2-one (HAMAH) and 8-amino-4-methyl-5-aza-3-octen-2-one (HAMAO) are described. Cu(II) and Ni(II) complexes with HAMAH have been isolated as four-coordinate complexes, the fourth coordination site being taken by imidazole, and have been structurally characterized. A Cu(II) complex involving HAMAO has been isolated as a highly insoluble polymeric species. Hydroxo bridging between the metal centres is indicated.     

Synthesis,characterization and crystal structures of cyclometallated Ru(II) carbonyl complexes formed by hydrazones

Cyclometallated Ru(II) complexes of the type [Ru(CO)(EPh₃)₂(L)] (E = P or As; L = tridentate hydrazone-derived ligand) have been obtained by refluxing an ethanolic solution of [RuHCl(CO)(PPh₃)₃] or [RuHCl(CO)(AsPh₃)₃] with the hydrazone derivatives H₂php (2-[(2,4-dinitro-phenyl)-hydrazonomethyl]-phenol), H₂phm (2-[(2,4-dinitro-phenyl)-hydrazonomethyl]-6-methoxy-phenol) and H₂phn (2-[(2,4-dinitro-phenyl)-hydrazonomethyl]-naphthalen-1-ol). The formation of stable cyclometallated complexes has been authenticated by single crystal X-ray structure determination of two of the complexes, and the mechanism of C–H activation is discussed in detail. The spectral (IR, UV–Vis and ¹H NMR) and electrochemical data for all the complexes are reported. Electrochemistry shows a substantial variation in the metal redox potentials with regard to the electronic nature of the substituents present in the hydrazone derivative.     

Synthesis, characterization, and X-ray crystal structures of copper(II) and nickel(II) complexes with Schiff base

New copper(II) complexes, [Cu₂L¹L²] · ClO₄ (I) and [Ni(L³)₂] (II), where L¹ is the monoanionic form of 2-[1-(2-emthylaminoethylimino)ethyl]phenol, L² is the dianionic form of N,N′-ethylene-bis(2-hydroxyacetophenonylideneimine), L³ is the mono-anionic form of 2-(1-iminoethyl)phenol, were prepared and characterized using elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction. In complex I, the Cu(1) atom is coordinated by the NNO tridentate ligand L¹ and the two phenolate O atoms of L², forming a square pyramidal geometry. The Cu(2) atom in complex I is coordinated by the NNOO tetradenate ligand L², forming a square planar geometry. The Ni atom in complex II is coordinated by two phenolate O and two imine N atoms from two ligands L³, forming a square planar geometry. In the crystal structure of I, the perchlorate anions are linked to the dinuclear copper(II) complex cations through intermolecular N-H...O hydrogen bonds. In the crystal structure of II, the mononuclear nickel complex molecules are linked through intermolecular N-H...O hydrogen bonds, forming a trimer.     

Syntheses, crystal structures and characterizations of new zinc (II) and lead (II) carboxylate-phosphonates

The syntheses, crystal structures and characterizations of two new divalent metal carboxylate-phosphonates, namely, Zn(H₃L)·2H₂O (1) and Pb(H₃L)(H₂O)₂ (2) (H₅L4-HO₂C–C₆H₄–CH₂N(CH₂PO₃H₂)₂₎ have been reported. Compound 1 features a 1D column structure in which the Zn(II) ions are tetrahedrally coordinated by four phosphonate oxygen atoms from four phosphonate ligands, and neighboring such 1D building blocks are further interconnected via hydrogen bonds into a 3D network. The carboxylate group of H₃L anion remains non-coordinated. Compound 2 has a 2D layer structure. Pb(II) ion is 7-coordinated by four phosphonate oxygen atoms from four phosphonate ligands and three aqua ligands. The interconnection of Pb(II) ions via bridging H₃L anions results in a 001 layer. The carboxylate group of the H₃L anion also remains non-coordinated and is oriented toward the interlayer space. Solid state luminescent spectrum of compound 1 exhibits a strong broad blue fluorescent emission band at 455 nm under excitation at 365 nm at room temperature.     

Complexes of nickel(II) carboxylates with pyridine and cyclam: crystal structures,mesomorphisms, and thermoelectrical properties

Nickel(II) carboxylates [Ni(CH₃(CH₂)₁₄COO)₂(H₂O)₂] (1) and [Ni(C₆H₅COO)₂(H₂O)₂] (2) were obtained from reactions of NiCl₂·6H₂O with CH₃(CH₂)₁₄COONa and C₆H₅COONa, respectively. Complex 1 reacted with pyridine (pyr) to form [Ni(CH₃(CH₂)₁₄COO)₂(pyr)₂(H₂O)₂] (3) and [Ni₂(μ₂-H₂O)(CH₃(CH₂)₁₄COO)₄(pyr)₄] (4) in the same reaction mixture, and reacted with cyclam to form an ionic complex, [Ni(CH₃(CH₂)₁₄COO)(cyclam)(H₂O)]CH₃(CH₂)₁₄COO·4H₂O (5). In contrast, 2 reacted with cyclam to form [Ni(C₆H₅COO)₂(cyclam)] (6). Finally, 6 reacted with p-(hexadecyloxy)pyridine (L) to form an ionic complex, [Ni(cyclam)(L)₂](C₆H₅COO)₂ (7). Complexes 3–6 were single crystals. All complexes have octahedral Ni(II) center(s) and were magnetic. Complexes with cyclam as co-ligand were more thermally stable than those with pyridine and its derivative, L. Complexes 3 and 4 were mesomorphic after partial loss of water and/or pyridine ligands on heating. The ionic complexes 5 and 7 were not mesomorphic, but showed good thermoelectrical behavior with negative S_e values in CHCl₃ (?0.28 mV K^?1 for 5; -0.39 mV K^?1 for 7) and positive S_e values in C₂H₅OH (+0.25 mV K^?1 for 5; +0.20 mV K^?1 for 7).     

Synthesis,characterization and crystal structures of Nickel(II) complexes containing sterically hindering Benzimidazole ligands

The synthesis, characterization, and crystal structures of two Ni(II) complexes with N,N-bis[2-(2′-benzimidazolyl)ethyl]amine (bbiea) (1) and N,N-bis[2-(1′-methyl-2′-benzimidazolyl)ethyl]amine (bmbea) (2) are reported. The nickel complex Ni(bbiea)(O₂C₂H₃)(ClO₄) (3) crystallizes in the space group C2/c, with a = 35.830(7), b = 14.130(3), c = 10.756(2)?Å, and β = 103.04(3)°. Compound 4, Ni(bmbea)(NO₃)₂, crystallizes in the space group P2₁/c, with a = 17.024(5), b = 16.516(4), c = 8.692(2)?Å, and β = 91.31(2)°. In 3, the bbiea ligand is coordinated to the Ni(II) ion in a facial conformation, whereas the bmbea ligand in 4 adopts meridonal geometry. Both complexes contain a single benzimidazole chelate and the remaining coordination sites are occupied by solvent molecules and/or counterions. Reactions involving large excesses of ligand-to-metal and different solvents produced only the mono-chelated complexes 3 and 4. No evidence for formation of bis-chelated complexes with Ni(II) was observed by MALDI-TOF and ESI-mass spectroscopy. Ligand field parameters for 3 and 4 were determined to be 9606 and 9862?cm^?1, respectively.     

Malonatobenzhydrazidediaquacobalt(II) hydrate: Synthesis,crystal and molecular structures

The coordination compound [Co(L)(Mal)(H₂O)₂]H₂O (I) (L is benzhydrazide, H₂Mal is malonic acid) has been synthesized and studied by IR spectroscopy, thermogravimetry, and X-ray diffraction. Crystals are triclinic, a = 7.610(4) Å, b = 7.854(2) Å, c = 12.751(2) Å, α = 75.12(3)°, β = 88.01(3)°, γ = 80.26(3)°, Z = 2, space group \(P\bar 1\). The structure is molecular. The Co²⁺ atom has a distorted octahedral coordination. The Co-O and Co-N bond lengths are 2.031-2.129(4) and 2.157(5) Å, respectively. The endocyclic O1Co1N1 bond angles are 77.3(2)° and 90.0(2)° in the five- and six-membered chelate rings, respectively. Molecules of complex I are linked via a great number of hydrogen bonds. The C…C contacts between phenyl rings additionally strengthen the structure.     

Two isomeric lead(II) carboxylate-phosphonates: syntheses, crystal structures and characterizations

Two isomeric layered lead(II) carboxylate-phosphonates of N-(phosphonomethyl)-N-methyl glycine ([MeN(CH₂CO₂H)(CH₂PO₃H₂)]=H₃L), namely, monoclinic Pb₃L₂·H₂O 1 and triclinic Pb₃L₂·H₂O 2, have been synthesized and structurally determined. Compound 1 synthesized by hydrothermal reaction at 150°C is monoclinic, space group C2/c with a=19.9872(6), b=11.9333(1) and c=15.8399(4) Å, β=110.432(3)°, V=3540.3(1) Å³, and Z=8. The structure of compound 1 features a 〈400〉 layer in which the lead(II) ions are bridged by both phosphonate and carboxylate groups. The lattice water molecules are located between the layers, forming hydrogen bonds with the non-coordinated carboxylate oxygen atoms. Compound 2 with a same empirical formula as compound 1 was synthesized by hydrothermal reaction at 170°C. It has a different layer structure from that of compound 1 due to the adoption of a different coordination mode for the ligand. It crystallizes in the triclinic system, space group with cell parameters of a=7.1370(6), b=11.522(1), c=11.950(1) Å, α=110.280(2), β=91.625(2), γ=95.614(2)°, V=915.3(1) Å³ and Z=2. The structure of compound 2 features a 〈020〉 metal carboxylate-phosphonate double layer built from 1D lead(II) carboxylate chains interconnected with 1D lead(II) phosphonate double chains. XRD powder patterns of compounds 1 and 2 indicate that each compound exists as a single phase.     

Synthesis,crystal structures,and characterization of copper(II) carboxylate complexes incorporating 1,10-phenanthroline and bipyridine

A series of Cu(II) carboxylate complexes (carboxylate?=?2-fluorobenzoic acid (2-HFBA) or 4-fluorobenzoic acid (4-HFBA)) containing either one chelating 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy) have been synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, and thermal analyses. In [Cu(bipy)(H₂O)(2-FBA)₂] (1), [Cu(bipy)(H₂O)(4-FBA)₂] (3), and [Cu(phen)(H₂O)(2-FBA)₂] (4), Cu is five-coordinate in a square pyramidal geometry and four-coordinate in [Cu(phen)(2-FBA)₂] (2). The four complexes are extended into 1-D chains through hydrogen-bonding and π?···?π interactions in 1 and 4, only hydrogen-bonding in 2, and π?···?π interactions in 3. These contacts lead to aggregation and supramolecular self-assembly.     

Synthesis,characterization, and crystal structures of cobalt(II), copper(II), and zinc(II) complexes of a bidentate iminophenol

A bidentate iminophenol (HL = 2-((4-methoxyphenylimino)methyl)-4,6-di-tert-butylphenol derived from condensation of 4-methoxyaniline and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) was mixed with divalent metal salts to form the corresponding mononuclear metal complexes [M^II(L)₂] (M = Co (1), Cu (2), and Zn (3)). The complexes are characterized by different spectroscopic and analytical tools. X-ray crystal structures of the complexes revealed homoleptic mononuclear complexes with MN₂O₂ coordination. The cobalt(II) (1) and zinc(II) (3) complexes display a pseudo-tetrahedral coordination geometry, whereas the copper(II) complex (2) exhibits a distorted square-planar coordination. The zinc(II) complex (3) emits at 460 nm with a twofold enhancement of emission with respect to the free iminophenol.     

Synthesis and x-ray crystal structure oftrans-diaquabis (4-morpholino) acetatocopper (II)

Summary An efficient procedure for the synthesis of the potassium salts of (4-morpholino)acetic acid, HL, and its -substituted derivatives is described. The title complex has been prepared and characterized by x-ray crystallography:a=8.505(2),b= 7.901(1),c=12.253(2) Å, =110.48(1)°, space groupP2₁/c,Z = 2, R_F=0.038 for 2300 observed MoK data. Hydrogen bonds link the centrosymmetrictrans-octahedral bis-chelated CuL₂(H₂O)₂ moieties into layers parallel to (100) in the crystal lattice.     

Syntheses, characterizations and crystal structures of two lead(II) phosphonate-sulfonate hybrid materials

Hydrothermal reactions of lead(II) acetate with 5-sulfoisophthalic acid monosodium salt (NaH₂BTS) and N-(phosphonomethyl)-N-methylglycine, MeN(CH₂CO₂H)(CH₂PO₃H₂) (H₃L¹), or a new aminodiphosphonic acid, 3-Pyridyl-CH₂N(CH₂PO₃H₂)₂ (H₄L²), afforded two novel lead(II) phosphonate-sulfonate hybrids, namely, Pb₃[L¹][BTS][H₂O]·H₂O 1 and Pb₂[HL³][BTS]·H₂O 2 (H₂L³=3-Pyridyl-CH₂(Me)N(CH₂PO₃H₂)). H₂L³ was formed as a result of the decomposition of one phosphonate group in H₄L² during the reaction. Compound 1 crystallizes in the triclinic space group with a=9.9148(4) Å, b=10.4382(4) Å, c=10.6926(2) Å, α=96.495(2)°, β=110.599(2)°, γ=98.433(2)°, V=1008.31(6) Å³, and Z=2. The structure of compound 1 features a 3D network built from the interconnection of hexanuclear Pb₆(L¹)₂ units and 1D double chains of lead(II) carboxylate-sulfonate. Compound 2 crystallizes in the monoclinic space group P2₁/c with a=9.5403(7) Å, b=11.6170(8) Å, c=19.7351(15) Å, β=97.918(2)°, V=2166.4(3) Å³, and Z=4. Compound 2 has a 3D network structure built by the cross-linkage of 1D double chains of lead(II) phosphonates and 2D layers of lead(II) carboxylate-sulfonate.     

Synthesis,crystal structures and characterization of two Cu(II) complexes with asymmetric sulfonamide Schiff-base ligands

Reaction of the N-tosyl-1,2-diaminopropane or N-tosyl-1,2-diaminobenzene with salicylaldehyde forms two new asymmetric sulfonamide Schiff bases, N-[2-(2-hydroxybenzylideneamino)propyl]-4-methylbenzenesulfonamide (H₂L¹ ) and N-[2-(2-hydroxybenzylideneamino)phenyl]-4-methylbenzenesulfonamide (H₂L² ). Two new complexes [CuL ^x (H₂O)] (x = 1 for 1, x = 2 for 2) constructed from H₂L ^x have been prepared and characterized via X-ray single-crystal diffraction, elemental analysis, FT-IR, UV-Vis, TGA, quantum chemical calculations, and photoluminescence measurements. Weak C–H ··· π, hydrogen bonds, π–π, and Cu ··· O weak interactions lead to 3-D supramolecular architecture, 1, and 1-D double chain, 2.     

Synthesis,characterization and X-ray crystal structures of polyether and ethylene bridged bis(azolyl) platinum(II) complexes

The preparation of platinum(II) complexes of the types [PtCl₂{Y(CH₂CH₂O) _x CH₂CH₂Y}] (Y: imidazol-1-yl, im; pyrazol-1-yl, pz or benzimidazol-1-yl, bim) and [PtI₂{im(CH₂CH₂O) _x CH₂CH₂im}] with varying ligand backbone length (x between 0 and 3) is described. A new bis(pyrazol-1-yl) polyether compound, pz(CH₂CH₂O)₂CH₂CH₂pz, is reported. Spectroscopic characterization of the complexes is discussed. Two crystal structures of the general formula [PtCl₂{im(CH₂CH₂O) _x CH₂CH₂im}] (x is 1 or 3) are also reported.     

Synthesis, crystal structures, electrochemical and spectroscopic properties of ruthenium(II) complexes containing diamino-1,3,5-triazine derivatives

Three Ru(II) complexes [Ru(bpy)₂(1-IQTNH)](ClO₄)₂ (1), [Ru(bpy)₂(2-QTNH)](ClO₄)₂ (2) and [Ru(bpy)₂(3-IQTNH)](ClO₄)₂ (3) (bpy = 2,2′-bipyridine, 1-IQTNH = 6-(isoquinolin-1-yl)-1,3,5-triazine- 2,4-diamine, 2-QTNH = 6-(quinolin-2-yl)-1,3,5-triazine- 2,4-diamine, 3-IQTNH = 6-(isoquinolin-3-yl)-1,3,5-triazine-2,4-diamine) have been synthesized and characterized by elemental analysis, ¹H NMR spectroscopy, electrospray ionization mass spectrometry and X-ray crystallography. The electrochemical and spectroscopic properties of the complexes differ from those of [Ru(bpy)₃]²⁺ owing to the structural differences between the ligands and their complexes.     

The stabilities and formation kinetics of some macrocycles with copper(II): crystal structures of some pendant arm macrocycles

Kinetics of complex formation and stability constants of tetra-(2-hydroxpropyl) substituted cyclam (L³) and cyclen (L⁴) with copper(II) have been studied in aqueous solution at room temperature. These data are compared to the corresponding parent compounds (cyclam L¹ and cyclen L²) in an attempt to define the effect of pendant arm upon kinetics and stability constants of the complexes. The kinetics were observed by stopped-flow measurements followed at multiwavelengths. These ligands were chosen to furnish information concerning effect of pendant groups and cavity size on the kinetics and stability of the complexes. Stopped-flow and spectrophotometric titration techniques were used for evaluation of the kinetics and stability constants, respectively. The apparent rate constants increase as CuL³?>?CuL⁴?>?CuL¹?>?CuL². Activation parameters and stability constants of the complexes were estimated. The effect of cavity size on the rate of reaction can be observed in CuL³?>?CuL⁴ and CuL¹?>?CuL² and the effect of pendant groups in CuL³?>?CuL¹ and CuL⁴?>?CuL². Mechanism of the complex formation reaction is proposed. The enhanced stability of the copper(II) complexes formed with L¹ and L² macrocyclic ligands is compared to those formed with analogous pendant arm species.     

Synthesis and x-ray crystal structures of isonipecotinamide derivatives as reverse amide analogues of fentanyl

Several isonipecotinamide derivatives which represent reverse amide derivatives of the potent analgetic agent fentanyl were prepared and evaluated for analgetic activity. The synthetic approaches utilized and stereochemical assignments are discussed. The most potent compound, 3 , displayed much weaker analgetic activity than fentanyl itself.