Synthesis,crystal structures,and catalytic property of dioxomolybdenum(VI) complexes with hydrazones

Two new dioxomolybdenum(VI) complexes, [MoO₂(L₁)] _n · 0.5 _n CH₃OH (I) and [MoO₂(L₂)(CH₃OH)] (II), where L1 and L₂ are the dianionic form of N′-[1-(4-diethylamino-2-hydroxyphenyl)methylidene]isonicotinohydrazide and N′-(2-hydroxy-4-methoxybenzylidene)-3-methylbenzohydrazide, respectively, were prepared and structurally characterized by physicochemical and spectroscopic methods and single-crystal X-ray determination. For complex I, a polymeric structure is obtained, which is linked by coordination of the pyridine N atoms to the Mo atoms of other [MoO₂(L₁)] units. Complex II is a mononuclear molybdenum compound. In both complexes, the Mo atoms are in octahedral coordination. The catalytic properties of the complexes indicate that they are efficient catalysts for sulfoxidation.     

2,5‐Bis[4‐methyl‐3‐(pyridin‐3‐yl)phenyl]‐1,3,4‐oxadiazole and its one‐dimensional polymeric complex with ZnCl2

2,5‐Bis[4‐methyl‐3‐(pyridin‐3‐yl)phenyl]‐1,3,4‐oxadiazole (L), C₂₆H₂₀N₄O, forms one‐dimensional chains via two types of intermolecular π–π interactions. In catena‐poly[[dichloridozinc(II)]‐μ‐2,5‐bis[4‐methyl‐3‐(pyridin‐3‐yl)phenyl]‐1,3,4‐oxadiazole], [ZnCl₂(C₂₆H₂₀N₄O)]_n, synthesized by the combination of L with ZnCl₂, the Zn^II centres are coordinated by two Cl atoms and two N atoms from two L ligands. [ZnCl₂L]_n forms one‐dimensional P (plus) and M (minus) helical chains, where the L ligand has different directions of twist. The helical chains stack together via interchain π–π and C—H...π interactions.     

Synthesis,Characterization and Molecular Structure of Ternary Cu(II) Complex with 1, 4, 8, 9‐Tetraazatriphenylene and L‐Phenylaninate

The complex [Cu(L‐Phe)(TATP)(H₂O)]ClO₄.0.5H₂O has been synthesized and investigated by elemental analysis, molar conductivity, spectroscopic and X‐ray diffraction methods, where TATP= 1,4,8,9‐tetraazatriphenylene and L‐phe = L‐phenylaninate group. The complex crystallizes in the triclinic space group PI with two molecules in a unit cell of dimensions a=0.5730(l), b = 1.0190(2), c = 2.1430(4), α= 97.50 (1)°, β = 95.33(3)°, γ= 102.85(1)°, V= 1.1998(4) nm³, R₁ = 0.0360, wR₂ = 0.0400. The crystal contains two independent [Cu(L‐Phe) (TATP)(H₂O)]⁺ complexes Cu1 and Cu2, having essentially the same distorted square‐pyramidal structure, where each Cu(II) ion coordinates two nitrogen atoms of TATP and the amino nitrogen and carboxylate oxygen atoms of L‐Phe in the equatorial positions and one water oxygen at an axial position.     

Complexes of [(iPrO)2P(O)NHC(S)NHCH2]2CH2 with Co(II), Ni(II), Zn(II), and Pd(II): Reaction of [(iPrO)2P(O)NHC(S)NHCH2]2 with KOH Leading to the Imidazolidine-2-Imine Derivative

Reaction of O,O′-diisopropylphosphoric acid isothiocyanate (iPrO)₂P(O)NCS with NH₂(CH₂)_nNH₂ (n = 3, 2) leads to the N-phosphorylated bis-thioureas [(iPrO)₂C(S)NHP(O) NH]₂Z (Z = —(CH₂)₃—, H₂L^I ; —(CH₂)₂—, H₂L^II ). Reaction of the potassium salt of H₂L^I with Co(II) and Zn(II) in aqueous EtOH leads to complexes of formula M₂(L-O,S)₂. The metal cation in both complexes is coordinated by two deprotonated ligands through the sulfur atoms of the thiocarbonyl groups and the oxygen atoms of the phosphoryl groups. Reaction of K₂L^I with Ni(II) and Pd(II) in the same conditions leads to M₂(L-N,S)₂ complexes. In both compounds, the metal center is found in a square-planar N₂S₂ environment formed by the C=S sulfur atoms and the P—N nitrogen atoms of two deprotonated ligands L^I . Reaction of H₂L^II with KOH leads to a product of heterocyclization, in which one of the thiourea fragments is retained. Compounds obtained were investigated by IR, UV-Vis, ¹H and ³¹P NMR spectroscopy, and microanalysis.     

Nature of the Chemical Bond and the Mutual Influence of Ligands in Co(III) Dioximinates

The results of MWG calculations of the electronic structures of real Co(III) complexes [Co(HD)₂L¹L²] ⁿ were used to analyze the electron density distribution and to determine the charges on atoms and configurations, where nis the charge of the complex and HD is the acid residue of dimethylglyoxime (H₂D); L¹= NH₃at L²= NH₃, Cl^–, Br^–, or I^–and L¹= L²= Cl^–; and L¹= H₂O or NO^– ₂at L²= NO^– ₂, with self-consistency over all atoms of the system and over d, s, and pconfigurations of cobalt. The mutual influence of the ligands (trans- and cis-) was shown to be determined by the atomic charges and bond orders on the axial coordinate and in the equatorial plane of the complex. The following order of the trans-effect was proposed: I^–> Br^–> Cl^–> NO^– ₂> NH₃> H₂O. The effects of the electronic factors on distorsion and conformational processes in the complexes were discussed.     

Synthesis,characterization, and biological investigation of new mixed-ligand complexes

A novel series of mixed-ligand complexes of 5,5′-{(1E,1E′)-1,4-phenelynebis(diazene-2,1-diyl)}bis(quinolin-8-ol) (H₂L₁) as a primary ligand and 4-aminoantipyrine(L₂) as a secondary ligand with Mn(II) ion were prepared using two general formulae: [Mn₂(H₂L₁)₂(L₂)₂X₄].4Cl (X = OH₂( 1 ), ONO₂⁻( 2 ), Cl=nil; OAc( 3 ), Cl = nil) and [Mn₂(H₂L₁)(L₂)₂(O₂SO₂)₂]( 4 ). Free ligands and their complexes were characterized. Electronic absorption spectra of the mixed-ligand complexes indicate a distorted octahedral geometry around the central metal ion, and the anions X⁻ are in the axial positions for all compounds. The ligands behave in a neutral bidentate manner, through nitrogen atoms and oxygen atoms of the carbonyl group (L₂), whereas H₂L₁ coordinated through nitrogen and OH groups as a neutral bidentate ligand. All complexes do not contain coordinated water molecules, but complex ( 1 ) contains four water molecules. The water molecules are removed in a single step. The complexes exhibited magnetic susceptibility corresponding to five unpaired electrons. The antimicrobial activity of the Mn(II) mixed-ligand complexes ( 1–4 ) against two gram-positive bacteria, three local gram-negative bacteria, and three fungi species was tested. Mn(II) mixed-ligand complex ( 2 ) exhibited significant antibacterial activity against Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas sp. Mixed-ligand complex ( 2 ) exhibited a high potential cytotoxicity against the growth of human lung cancer cells.     

catena‐Poly[[aquacopper(II)]‐μ‐hydroxido‐μ‐naphthalene‐1‐carboxylato‐κ2O:O′]: effect of a bulky aromatic skeleton in self‐assembly

In the title coordination polymer, [Cu(C₁₁H₇O₂)(OH)(H₂O)]_n, the Cu^II center is five‐coordinated by two O atoms from two different naphthalene‐1‐carboxylate (L) ligands, one O atom from one coordinated water molecule and two O atoms from two hydroxide anions. L ligands and hydroxide anions jointly bridge adjacent Cu^II centers to generate a one‐dimensional chain along the b‐axis direction. The results reveal that the steric bulk of the naphthalene ring system in L may play an important role in the formation of the title complex.     

Pendant—armed Unsymmetrical Aza—macrocycles：Syntheses,Coordination Behavior and Crystal Structure of a Dinuclear Cadmium Complex

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Syntheses,Crystal Structures,and Thermal Behavior of Co(phen)(HL)2 and [Co2(phen)2(H2O)4L2]·H2O with H2L = Pimelic Acid

Two Co^II complexes, Co(phen)(HL)₂ ( 1 ) and [Co₂(phen)₂(H₂O)₄L₂]·H₂O ( 2 ) (H₂L = HOOC‐(CH₂)₅‐COOH), were synthesized and structurally characterized on the basis of single crystal X‐ray diffraction data. In complex 1 the Co atoms are tetrahedrally coordinated by two N atoms of one phen ligand and two O atoms of different hydrogenpimelato ligands. Through π—π stacking interactions between carboxyl group and phen ligand, the complex molecules are assembled into 1D columnar chains, which are connected by intermolecular hydrogen bonds. Complex 2 consists of the centrosymmetric dinuclear [Co₂(phen)₂(H₂O)₄L₂] molecules and hydrogen bonded H₂O molecules. The Co atoms are each octahedrally surrounded by two N atoms of one phen ligand and four O atoms from two bis‐monodentate pimelato ligands and two H₂O molecules at the trans positions. The results about thermal analyses, which were performed in flowing N₂ atmosphere, on both complexes were discussed. Crystal data: ( 1 ) C2/c (no. 15), a = 13.491(1)Å, b = 9.828(1)Å, c = 19.392(2)Å, β = 100.648(1)°, U = 2526.9(4)ų, Z = 4; ( 2 ) P1 (no. 2), a = 11.558(1)Å, b = 11.947(3)Å, c = 15.211(1)Å, α = 86.17(1)°, β = 75.55(1)°, γ = 69.95(1)°, U = 1910.3(3)ų, Z = 2.     

Synthesis, crystal structure and spectroscopic properties of two new complexes containing azido or dicyanamido bridges

Two new complexes, [Cu(L₁){N(CN)₂}]·ClO₄ (1) (L₁ is 1,8-dimethyl-1,3,6,8,10,13-hexa-azacyclotetradecane) and [Co(L₂)(N₃)₂]·ClO₄ (2) (L₂ is 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane) have been synthesized and characterized. The compounds crystallize in the monoclinic system P2₁ space group for 1 and P2₁/n for 2. Single crystal X-ray analysis reveals that the compound 1 assumes a one-dimensional structure via hydrogen-bonding interactions, in which each Cu(II) ion is coordinated by four nitrogen atoms from ligand L₁ and one nitrogen atom from [N(CN)₂]⁻ anion. For compound 2, each Co(III) ion is coordinated by four nitrogen atoms of ligand L₂ and two nitrogen atoms from N₃ ⁻ anion.     

A novel three‐dimensional AgI coordination polymer based on mixed naphthalene‐1,5‐disulfonate and aminoacetate ligands

The three‐dimensional coordination polymer poly[[bis(μ₃‐2‐aminoacetato)di‐μ‐aqua‐μ₃‐(naphthalene‐1,5‐disulfonato)‐hexasilver(I)] dihydrate], {[Ag₆(C₁₀H₆O₆S₂)(C₂H₄NO₂)₄(H₂O)₂]·2H₂O}_n, based on mixed naphthalene‐1,5‐disulfonate (L1) and 2‐aminoacetate (L2) ligands, contains two Ag^I centres (Ag1 and Ag4) in general positions, and another two (Ag2 and Ag3) on inversion centres. Ag1 is five‐coordinated by three O atoms from one L1 anion, one L2 anion and one water molecule, one N atom from one L2 anion and one Ag^I cation in a distorted trigonal–bipyramidal coordination geometry. Ag2 is surrounded by four O atoms from two L2 anions and two water molecules, and two Ag^I cations in a slightly octahedral coordination geometry. Ag3 is four‐coordinated by two O atoms from two L2 anions and two Ag^I cations in a slightly distorted square geometry, while Ag4 is also four‐coordinated by two O atoms from one L1 and one L2 ligand, one N atom from another L2 anion, and one Ag^I cation, exhibiting a distorted tetrahedral coordination geometry. In the crystal structure, there are two one‐dimensional chains nearly perpendicular to one another (interchain angle = 87.0°). The chains are connected by water molecules to give a two‐dimensional layer, and the layers are further bridged by L1 anions to generate a novel three‐dimensional framework. Moreover, hydrogen‐bonding interactions consolidate the network.     

Syntheses,Structural, and Spectroscopic Properties of Copper(II) Complexes of Constrained Macrocyclic Ligands

The complexes [Cu(L¹)(H₂O)₂](BF₄)₂ · 2H₂O ( 1 ) [L¹ = 5, 16‐dimethyl‐2, 6, 13, 17‐tetraazatricyclo(14, 4, 0^1.18,0^7.12)docosane] and 0.5[Cu(L²)(NO₃)₂][Cu(L²)](NO₃)₂ ( 2 ) [L² = dibenzyl‐5, 16‐dimethyl‐2, 6, 13, 17‐tetraazatricyclo(14, 4, 0^1.18,0^7.12)docosane] were synthesized and characterized by single crystal X‐ray analyses. In these constrained macrocycles, the central copper(II) atoms are in a tetragonally distorted octahedral environment with four nitrogen atoms of the macrocyclic ligands in equatorial positions and oxygen atoms from either water molecules or nitrato groups in axial positions. The macrocyclic ligands in both complexes adopt the most stable trans‐III conformation. The Cu–N distances [1.999(7)–2.095(7) Å] are typical for such complexes, but the axial ligands are weakly coordinating Cu–OH₂ bonds [2.693(3) Å] and Cu–ONO₂ bonds [2.873(7) Å] due to the combination of the pseudo Jahn–Teller effect and strong in‐plane ligand field. The crystals are stabilized by a three‐dimensional network by hydrogen bonds that are formed among the secondary nitrogen hydrogen atoms, oxygen atoms of water molecules, fluorine atoms of BF₄^–, and oxygen atoms of NO₃^–. The electronic absorption and IR spectroscopic properties are also discussed.     

Synthesis and Crystal Structures of S 2 O 2 Macrocycle L, and its Silver(I) and Platinum(II) Complexes (Where L = 5,8-dioxa-2,11-dithia-[12]-o-cyclophane)

The S₂O₂-donor macrocycle, L(5,8-dioxa-2,11-dithia-[12]-o-cyclophane or 3,4-benzo-1,6-dithia-9,12-dioxocyclo-tetradecane-3-ene) was synthesized by ring closure reaction of 2,2'-(ethylenedioxy)diethanethiol with ,'-dibromo-o-xyleneunder high dilution and crystallized from methanol. The X-ray structure of L has a C₂ axis and is shown to have two S atoms oriented exodentate and two O atoms positionedendodentate to the ring cavity. Reaction of AgNO₃ with L affords monomeric [Ag(L)(NO₃)], (1)in which the Ag atom is in a distorted trigonal plane coordinated by two S atoms in a ring and to one O atom from the NO₃ ^- ion. The behavior of complex 1 in solution was also characterized by NMR titration. Reaction between K₂PtCl₄ and L affords [Pt(L)Cl₂], (2) in which the Pt atom has a distorted square-planar environment, coordinated to two S atoms of Land to two Cl^- ions in a cis arrangement.     

Poly[(N,N‐dimethylformamide‐κO)(μ3‐4,4′‐ethylenedibenzoato‐κ5O,O′:O′:O′′,O′′′)(pyrazino[2,3‐f][1,10]phenanthroline‐κ2N8,N9)lead(II)]

In the title Pb^II coordination polymer, [Pb(C₁₆H₁₀O₄)(C₁₄H₈N₄)(C₃H₇NO)]_n, each Pb^II atom is eight‐coordinated by two chelating N atoms from one pyrazino[2,3‐f][1,10]phenanthroline (L) ligand, one dimethylformamide (DMF) O atom and five carboxylate O atoms from three different 4,4′‐ethylenedibenzoate (eedb) ligands. The eedb dianions bridge neighbouring Pb^II centres through four typical Pb—O bonds and one longer Pb—O interaction to form a two‐dimensional structure. The C atoms from the L and eedb ligands form C—H...O hydrogen bonds with the O atoms of eedb and DMF ligands, which further stabilize the structure. The title compound is the first Pb^II coordination polymer incorporating the L ligand.     

Nuclear spin relaxation in biaxial liquid crystal phases

Abstract

The orientation-dependent spin-lattice relaxation rates for biaxial liquid crystal phases are given explicitly in terms of spectral densities J _mLm′L (ω) described by Berggren et al. (1993, J. chem. Phys., 99, 6180). It is recognized that the ‘biaxial’ spectral densities are not observed in biaxial phases unless the director is oriented away from the external magnetic field.     

1,1′‐[(Ethane‐1,2‐diyldioxy)di‐o‐phenylene]bis(indoline‐2,3‐dione) (L) and a novel [Ag2L2]2+ metallocycle based on coordination‐driven Ag—O and Ag—π bonds

1,1′‐[(Ethane‐1,2‐diyldioxy)di‐o‐phenylene]bis(indoline‐2,3‐dione), C₃₂H₂₄N₂O₆, L or (I), adopts a trans conformation with the two terminal indoline‐2,3‐dione groups located on opposite sides of the central ether bridge, as required by a centre of inversion located at the mid‐point of the ethane C—C bond. However, in the discrete binuclear Ag^I metallocycle complex salt bis{μ‐1,1′‐[(ethane‐1,2‐diyldioxy)di‐o‐phenylene]bis(indoline‐2,3‐dione)}disilver(I) bis(hexafluoridoantimonate), [Ag₂(C₃₂H₂₄N₂O₆)₂][SbF₆]₂, (II), synthesized by combination of L with AgSbF₆, L adopts a gauche conformation to bind Ag^Ivia the two indolinedione O atoms and two C atoms from the phenoxy ring. One dione O atom from the opposite side of the ether bridge completes the irregular coordination environment of each Ag^I atom. The complex is on a centre of inversion located between the Ag^I atoms. In the solid state, these binuclear [Ag₂L₂]²⁺ metallocycles stack together via intermolecular π–π interactions to generate a one‐dimensional chain motif, with the [SbF₆]⁻ counter‐ions, which are disordered, located between the chains.     

A three‐dimensional PbII coordination framework: poly[[μ4‐(E)‐2,2′‐(diazene‐1,2‐diyl)dibenzoato]dimethanollead(II)]

In the title coordination polymer, [Pb(C₁₄H₈N₂O₄)(CH₃OH)₂]_n, the asymmetric unit contains half of a Pb^II cation, half of a 2,2′‐(diazene‐1,2‐diyl)dibenzoate dianionic ligand (denoted L²⁻) and one methanol ligand. Each Pb^II centre is eight‐coordinated by six O atoms of chelating/bridging carboxylate groups from four L²⁻ ligands and two O atoms from two terminal methanol ligands, forming a distorted dodecahedron. The [PbL₂(MeOH)₂] subunits are interlinked via the sharing of two carboxylate O atoms to form a one‐dimensional [PbL₂(MeOH)₂]_n chain. Adjacent chains are further connected by L²⁻ ligands, giving rise to a two‐dimensional layer, and these layers are bridged by L²⁻ linkers to afford a three‐dimensional framework with a 4¹²6³ topology.     

3,5‐Bis{4‐[(benzimidazol‐1‐yl)methyl]phenyl}‐4H‐1,2,4‐triazol‐4‐amine and its one‐dimensional polymeric complex with HgCl2

The molecule of 3,5‐bis{4‐[(benzimidazol‐1‐yl)methyl]phenyl}‐4H‐1,2,4‐triazol‐4‐amine (L), C₃₀H₂₄N₈, has an antiperiplanar conformation of the two terminal benzimidazole groups and forms two‐dimensional networks along the crystallographic b axis via two types of intermolecular hydrogen bonds. However, in catena‐poly[[[dichloridomercury(II)]‐μ‐3,5‐bis{4‐[(benzimidazol‐1‐yl)methyl]phenyl}‐4H‐1,2,4‐triazol‐4‐amine] dichloromethane hemisolvate], {[HgCl₂(C₃₀H₂₄N₈)]·0.5CH₂Cl₂}_n, synthesized by the combination of L with HgCl₂, the L ligand adopts a synperiplanar conformation. The Hg^II cation lies in a distorted tetrahedral environment, which is defined by two N atoms and two Cl atoms to form a one‐dimensional zigzag chain. These zigzag chains stack via hydrogen bonds which expand the dimensionality of the structure from one to two.     

FeIII in a low‐spin state in caesium bis[3‐ethoxysalicylaldehyde 4‐methylthiosemicarbazonato(2–)‐κ3O2,N1,S]ferrate(III) methanol monosolvate

The synthesis and crystal structure (at 100 K) of the title compound, Cs[Fe(C₁₁H₁₃N₃O₂S₂)₂]·CH₃OH, is reported. The asymmetric unit consists of an octahedral [Fe^III(L)₂]⁻ fragment, where L²⁻ is 3‐ethoxysalicylaldehyde 4‐methylthiosemicarbazonate(2−) {systematic name: [2‐(3‐ethoxy‐2‐oxidobenzylidene)hydrazin‐1‐ylidene](methylamino)methanethiolate}, a caesium cation and a methanol solvent molecule. Each L²⁻ ligand binds through the thiolate S, the imine N and the phenolate O atoms as donors, resulting in an Fe^IIIS₂N₂O₂ chromophore. The O,N,S‐coordinating ligands are orientated in two perpendicular planes, with the O and S atoms in cis positions and the N atoms in trans positions. The Fe^III cation is in the low‐spin state at 100 K.     

Two novel silver(I) coordination polymers: poly[(μ2‐2‐aminopyrimidine‐κ2N1:N3)bis(μ3‐thiocyanato‐κ3S:S:S)disilver(I)] and poly[(2‐amino‐4,6‐dimethylpyrimidine‐κN)(μ3‐thiocyanato‐κ3N:S:S)silver(I)]

2‐Aminopyrimidine (L1) and 2‐amino‐4,6‐dimethylpyrimidine (L2) have been used to create the two novel title complexes, [Ag₂(NCS)₂(C₄H₅N₃)]_n, (I), and [Ag(NCS)(C₆H₉N₃)]_n, (II). The structures of complexes (I) and (II) are mainly directed by the steric properties of the ligands. In (I), the L1 ligand is bisected by a twofold rotation axis running through the amine N atom and opposite C atoms of the pyrimidine ring. The thiocyanate anion adopts the rare μ₃‐κ³S coordination mode to link three tetrahedrally coordinated Ag^I ions into a two‐dimensional honeycomb‐like 6³ net. The L1 ligands further extend the two‐dimensional sheet to form a three‐dimensional framework by bridging Ag^I ions in adjacent layers. In (II), with three formula units in the asymmetric unit, the L2 ligand bonds to a single Ag^I ion in a monodentate fashion, while the thiocyanate anions adopt a μ₃‐κ¹N,κ²S coordination mode to link the AgL2 subunits to form two‐dimensional sheets. These layers are linked by N—H...N hydrogen bonds between the noncoordinated amino H atoms and both thiocyanate and pyrimidine N atoms.