Discrete Cations Research Articles

Synthesis and Crystal Structure Studies of a New Complex of Co (III)-Schiff Base Derivative Derived from Isonicotinohydrazide

A new Co(III) complex prepared by the reaction of N'–(1–(pyridin–2 yl)ethylidene) isonicotinohydrazide (H2L) with Co(II) ion is reported in this paper. The H2L ligand is structurally characterized by elemental analysis, NMR, and infrared spectroscopies. The mononuclear complex [Co(HL)2]·Cl·3H2O (1), is characterized by infrared spectroscopy, elemental analysis, conductance, magnetic room temperature measurement and single X-ray diffraction. The complex crystallizes in the monoclinic system with space group P21/c. The parameters of the unit cell are a = 9.6818(3) Å; b = 25.1587(6) Å; c = 11.5481(3) Å; β = 101.797(3) °; Z = 4; Rint = 0.0313 and wR(F2) = 0.0812. The asymmetric unit of the compound contains a discrete [Co(HL)2]+ cation one free chloride anion and three uncoordinated water molecules. In the discrete cation one Co3+ ion two organic ligand molecules are present. The coordination polyhedron around the Co3+ center is best described as a distorted octahedral with CoN4O2 chromophore. The crystal structure of the complex is stabilized by intramolecular and intermolecular hydrogen bonds.

Synthesis, structure and reactivity of a boron-containing spirocycle carbanion

The crystal structure, electronic characteristic, as well as the formation process, and nucleophilic reactivity of an unexpected boron-containing carbanion are presented. Its structure consists of a discrete cation and a spirocycle structure, in which the sp 3 hybrid C7 atom connects the mesityl substituted oxaborole unit and the puckered anthracene moiety. • A novel boron-containing carbanion with distinct structural characteristics was synthesized, which was composed of a discrete [K(cryptand)] + ion and a spirocycle anion. • The formation and electronic structure of carbanion were explored through DFT calculations. • The nucleophilic reactivity of carbanion with some chlorosilane or halogenated alkanes in THF solution was evaluated. Carbanion ( 2 ) was synthesized by the deprotonation strategy through treatment of (2-(anthracen-9-yl)phenyl)(hydroxy)(mesityl)borane ( 1-H ) with KN(SiMe 3 ) 2 in the presence of [2,2,2]-cryptand in tetrahydrofuran (THF) solution followed by crystallization of the crude product from cooled THF. Its crystal structure and electronic properties are presented, as well as the formation process and nucleophilic reactivity with chlorosilane or halogenated alkanes.

Tea polyphenols mediated Zero-valent Iron/Reduced graphene oxide nanocomposites for electrochemical determination of Hg2+

Herein, we have developed a chemically modified glassy carbon electrode (GCE) using tea polyphenols mediated zero-valent iron/reduced graphene oxide nanocomposites (rGO-ZVI-P) for rapid determination of Hg2+ in water. Highly conductive rGO-ZVI-P were fabricated by a green chemical method using tea polyphenols as the reductant. The rGO-ZVI-P shows a unique affinity to aqueous Hg2+ due to a synergy between ZVI and rGO. The rGO-ZVI-P electrochemical sensor shows optimal performance for Hg2+ determination in pH 5.00 phosphate buffer and 180 s accumulation time at −1.2 V accumulation potential used under square wave anode stripping voltammetry (SWASV). At these conditions, the Hg2+ determination sensitivity is 41.42 μA/μM and the determination limit is 1.2 nM. There are no interferences to the rGO-ZVI-P modified GCE sensor in the presence of 0.5 μM Cd2+, 0.5 μM Pb2+, and 0.5 μM Cu2+ in solution, either in discrete cations or multi-cations modes. Moreover, the typical chemical species found in the matrix of river water samples do not interfere with the as-fabricated Hg2+ electrochemical sensor. The Hg2+ determination by the rGO-ZVI-P modified GCE sensor is repeatable, stable, and robust, and it has potential in environmental applications.

Air-Stable Dy(III)-Macrocycle Enantiomers: From Chiral to Polar Space Group

Air-Stable Dy(III)-Macrocycle Enantiomers: From Chiral to Polar Space Group

A flame retardant-hardener for epoxy resins: Synthesis, structural, and DFT studies of the [Cu(H2NC2H4NH2)2(H2O)Cl]Cl complex.

The aqua-bis(ethylenediamine)-chloro-copper(II) chloride complex, [Cu(en)2(H2O)(Cl)]Cl (1), was synthesized by direct interaction of CuCl2×2H2O with pepa (pepa is a polyethylenepolyamine containing ethylenediamine (en)). The crystalline complex 1 was characterized by IR spectra and structurally studied. Crystals of this complex consist of the [Cu(en)2(H2O)(Cl)]+ discrete cations, whose Cu2+ ion is chelated by two en molecules. The Cu(II) coordination polyhedron has the shape of an elongated square bipyramid, in which four nitrogen atoms of the -NH2 groups of en molecules form the base of this bipyramid, and the oxygen atom of the water molecule and Cl- are in its apical positions. Three-dimensional framework 1 is formed due to hydrogen bonds O-H…Cl and N-H…Cl. The Cu(II)-(H2NC2H4NH2) chelation was studied by DFT using the 6-31G* basis set. The calculated electron-stereochemical parameters are in good agreement with the ability of complex 1 to simultaneously be a flame retardant and a curing agent of epoxy resins.

Heteroleptic cuprous complexes of a diimine MePBO ligand and their structure influence on phosphorescent color: Syntheses, structure characterizations, properties and TD‐DFT calculations

AbstractThree new heteroleptic [Cu(NN)P2]+ type cuprous complexes 1–3 were designed and synthesized by utilizing a diimine ligand 5‐methyl‐2‐(2′‐pyridyl)‐benzoxazole (MePBO) and different phosphine ligands PPh3 (1), m‐Tol3P (2) and POP (3), (PPh3=triphenylphosphine, m‐Tol3P=tris(3‐methylphenyl)phosphine, POP=bis[2‐(diphenylphosphino)phenyl]ether), respectively. All complexes were characterized by single‐crystal X‐ray diffraction, spectroscopic analysis (IR, UV‐Vis), elemental analysis, and photoluminescence study. Single‐crystal X‐ray diffraction revealed that complexes 1–3 all adopt discrete cation complex structure with a tetrahedral CuN2P2 coordination geometry with diverse P−Cu−P angles. Their UV‐Vis absorption spectra exhibit a blue‐shift sequence under the enlarging of P−Cu−P angle from 3 to 2 then to 1. The PL emission peak wavelengths of 1–3 also present similar blue‐shift sequence (3→1/2). Their microsecond PL lifetime indicates that their PL behavior belongs to phosphorescence. TD‐DFT calculation and wavefunction analysis illuminate that the S1 and T1 states of 1–3 should all be assigned as (ML+L′L)CT states. Their UV‐Vis absorption and phosphorescence should be attributed to the charge transfer from the P−Cu−P segment to the MePBO ligand. Therefore, as P−Cu−P angle increases (lower HOMO), the energy of S1 and T1 states also increase, following the change of PL color. Additionally, the steric hindrance from substituents of phosphine ligand, as well as extra strong intra‐molecular π−π stacking interactions should effectively inhibit nonradiative decay so that an abnormal PL emission blue‐shift is observed from 1 to 2.

New Low-Melting Triply Charged Homoleptic Cr(III)-Based Ionic Liquids in Comparison to Their Singly Charged Heteroleptic Analogues.

A series of new low-melting triply charged homoleptic Cr(III)-based ionic liquids of the general formula (RMIm)3[Cr(NCS)6] (R = methyl, ethyl, n-butyl, benzyl) is reported. Their syntheses and properties are described in comparison to their singly charged heteroleptic analogues of the general formula (RMIm)[Cr(NCS)4L2] (R = methyl, ethyl, n-butyl, benzyl; L = pyridine, γ-picoline). In total, sixteen new Reineckate related salts with large imidazolium cations are described. Out of these, five compounds were crystallized, and their structures determined by single-crystal X-ray structure analyses. They all consisted of discrete anions and cations with octahedrally coordinated Cr(III) ions. In the structures, various hydrogen contacts interconnect the entities to build up hydrogen bonded networks. Thermal investigations showed relatively low melting points for the homoleptic complexes. The compounds with the [Cr(NCS)6]3− anion melt without decomposition and are stable up to 200 K above their melting points. The complex salts with the [Cr(NCS)4L2]− anion, in contrast, start to decompose and lose L molecules (Pyr or Pic) already at the melting point.

Two salts of the 6,6-di-fluoro-6H-dibenzo[c,e][1,2]oxaborinin-6-ide anion with different cations.

The crystal structures are reported of the 6,6-di-fluoro-6H-dibenzo[c,e][1,2]oxaborinin-6-ide (or 9,9-di-fluoro-10-oxa-9-boraphenanthren-9-ide) anion with two different cations, namely, potassium 6,6-di-fluoro-6H-dibenzo[c,e][1,2]oxaborinin-6-ide, K+·C12H8BF2O-, (II), featuring a polymeric structure, and bis-(tetra-phenyl-phospho-nium) bis-(6,6-di-fluoro-6H-dibenzo[c,e][1,2]oxaborinin-6-ide) aceto-nitrile tris-olvate, 2C24H20P+·2C12H8BF2O-·3CH3CN, (III), which is composed of discrete cations, anions and aceto-nitrile solvent mol-ecules linked by C-H⋯O, C-H⋯N and C-H⋯F hydrogen bonds. There are only minor differences in the geometrical parameters of the anions in these structures.

Hypercoordinated triorganotellurium(IV) derivatives of chalcogen-centred organophosphorus ligands

Triorganotelluronium complexes of type [{2-(Me2NCH2)C6H4}nPh3-nTe]L [(L = S2PMe2, n = 3 (1), 1 (2); L = (EPPh2)2N, E = S, n = 3 (3); E = Se, n = 3 (4), 2 (5), 1 (6) and L = (SPPh2)(O2SC6H4CH3-4)N, n = 3 (7), 2 (8), 1 (9)] were obtained by salt metathesis reactions between triaryltelluronium halides of type [{2-(Me2NCH2)C6H4}nPh3-nTe]X (X = Cl, Br) and the alkali metal salt of the corresponding organophosphorus acid in a 1:1 molar ratio. The new ionic species were characterized by multinuclear NMR spectroscopy and mass spectrometry. The NMR spectra show similar resonances for each series of triorganotelluronium complexes (1 and 2, 3–6 and 7–9). The 1H NMR spectra suggest intramolecularly coordinated pendant arms in solution for compounds bearing two or three 2-(Me2NCH2)C6H4 groups. Single-crystal X-ray diffraction studies revealed strong N→Te intramolecular interactions in compounds 2, 4, 6 and 7, which result in hypercoordinated triorganotelluronium(IV) cations with different distorted coordination geometries. Further secondary bonding interactions (S⋅⋅⋅Te in 2 and Se⋅⋅⋅Te in 6) lead to cation–anion associations, while H⋅⋅⋅E (E = S, Se) contacts between cations and anions resulted in different supramolecular networks in 2, 4 and 6 and in discrete cation–anion pairs in 7.

Ibuprofen-thiadiazole hybrid compounds: Synthesis, vibrational analysis and molecular structure of 5-(1-(4-isobutylphenyl)ethyl)-1,3,4-thiadiazol-2-amine hydrochloride

The ibuprofen derivative 5-(1-(4-isobutylphenyl)ethyl)-1,3,4-thiadiazol-2-amine hydrochloride is prepared by via cyclization of ibuprofen with thiosemicarbazide in the presence of POCl3. The compound has been characterized by using FT-IR and multinuclear (1H and 13C) NMR spectroscopies, and elemental analysis. The molecular structure in crystalline phase has been determined by single crystal X-Ray diffraction. The compound crystallizes in the triclinic system with space group P-1 as discrete cations and chloride anions with two enantiomers present in the asymmetric unit. A full vibrational analysis of the FT-IR and FT-Raman spectra has been performed in conjunction with quantum chemical calculations. Experimental data agree with the occurrence of the thiadiazole NH protonated form in the solid phase. The observation of the ν(NN) and δ(CNN) normal modes as strong signals in the infrared and Raman spectra at 1189 (1180 cm−1) and 774 cm−1 suggests a NN bond with partial double bond character in the thiadiazole moiety, in good agreement with the computed values at the B3LYP/6-311++G(d,p) level of approximation. The NBO analysis showed that both, the sulfur lone pair and the exocyclic amine nitrogen lone pair orbitals contribute to strong resonance interactions with the adjacent π*(N2=C8) antibonding orbital of the protonated thiadiazole group.

The role of anions in adsorbate-induced anchoring transitions of liquid crystals on surfaces with discrete cation binding sites.

We report a combined theoretical and experimental effort to elucidate systematically for the first time the influence of anions of transition metal salt-decorated surfaces on the orientations of supported films of nematic liquid crystals (LCs) and adsorbate-induced orientational transitions of these LC films. Guided by computational chemistry predictions, we find that nitrate anions weaken the binding of 4'-n-pentyl-4-biphenylcarbonitrile (5CB) to transition metal cations, as compared to perchlorate salts, although binding is still sufficiently strong to induce homeotropic (perpendicular) orientations of 5CB. In addition, we find the orientations of the LC to be correlated across all metal cations investigated by a molecular anchoring energy density that is calculated as the product of the single-site binding energy and metal cation binding site density on the surface. The weaker single-site binding energy caused by nitrate also facilitates competitive binding of adsorbates to the metal cations, leading to more facile orientational transitions induced by adsorbates. Finally, our analysis suggests that nitrate anions recruit water via hydrogen bonding to the metal binding sites, modulating further the relative net binding energies of 5CB and adsorbates to surfaces decorated with metal nitrates. After accounting for the presence of water, we find a universal exponential relationship between the calculated displacement free energies and measured dynamic response of LCs to adsorbates for all metal salts studied, independent of the metal salt anion.

Deca-chloro-cyclo-penta-silanes coordinated by pairs of chloride anions, with different cations, but the same solvent mol-ecules.

We have determined the crystal structures of two deca-chloro-cyclo-penta-silanes, namely bis-(tetra-n-butyl-ammonium) dichloride deca-chloro-cyclo-penta-silane di-chloro-methane disolvate, 2C16H36N+·2Cl-·Si5Cl10·2CH2Cl2, (I), and bis-(tetra-ethyl-ammonium) dichloride deca-chloro-cyclo-penta-silane di-chloro-methane disolvate, 2C8H20N+·2Cl-·Si5Cl10·2CH2Cl2, (II), both of which crystallize with discrete cations, anions, and solvent mol-ecules. In (I), the complete deca-chloro-cyclo-penta-silane ring is generated by a crystallographic twofold rotation axis. In (II), one cation is located on a general position and the other two are disordered about centres of inversion. These are the first structures featuring the structural motif of a five-membered cyclo-penta-silane ring coordinated from both sides by a chloride ion. The extended structures of (I) and (II) feature numerous C-H⋯Cl inter-actions. In (II), the N atoms are located on centres of inversion and as a result, the ethyl-ene chains are disordered over equally occupied orientations.

Synthesis, crystal structures, hydrogen bonding graph-sets and theoretical studies of nickel (+II) co-ordinations with pyridine-2,6-dicarboxamide oxime

The pyridine-2,6-dicarboxamide oxime, C 7 H 9 N 5 O 2 , was Synthesis and characterises with 1 H NMR and FTIR spectroscopy . The reaction of this ligand with nickel (II) perchlorate yielded green crystals of formula [Ni(C 7 H 9 N 5 O 2 ) 2 ] 2+ ,2[ClO 4 ] - , which crystallized in the monoclinic space group C2/c with a = 14.915(2), b = 0.895(2), c = 8.205(1) A, β = 114.69(1), and Z = 4. The complex consists of discrete cations (+II) and one perchlorate anion, the cations existing in a slightly distorted octahedral complex with bonding through the heterocyclic and oxime nitrogen atoms. The structure is held together through N-H…O, O-H…O and C-H...O hydrogen bonds occurring between the coordinated oxime molecules and the perchlorate counter-ion. Computational investigations of nickel(II) complex are done by using M062X method with 6-31+G(d)(LANL2DZ) basis set in vacuo.

Effect of the counterion and guest molecules on the crystal structures of the coordination compounds with the Cu2(HL) 2 2+ cation (H2L = 4,4’-[2-(3-hydroxyiminobutyl)imino]biphenyl): Syntheses, structures, and magnetic properties

The molecular and crystal structures of complexes [Cu2(HL)2(CH3OH)2](BF4)2 ∙ C6H3Cl3 (I), [Cu2(HL)2(H2O)2](1,4-O2CС6Н4CO2) (II), and [Cu2(HL)2(H2O)2](4,4’-O2CС6Н4С6Н4CO2) (III) (H2L is 4,4’-[2-(3-hydroxyiminobutyl)imino]biphenyl, C6H3Cl3 is 1,2,4-trichlorobenzene) are determined by X-ray diffraction analyses. The crystalline lattices of complexes I and II contain discrete binuclear cations Cu2(HL) 2 2+ , whereas the crystalline lattice of compound III contains both discrete cations Cu2(HL) 2 2+ and polymer chains [Cu2(HL) 2 2+ ]n. In compounds I–III, the crystalline lattice units are joined by hydrogen bonds. The analysis of the temperature dependence of the magnetic susceptibility shows that the magnetic properties of compound III are determined only by antiferromagnetic interactions of the Cu2+ ions within the cations Cu2(HL) 2 2+

Air‐Stable, Well‐Soluble AI2[Nb6Cl18] Cluster Compounds (AI = Organic Cation): A New Route for Preparation, Single‐Crystal Structures, Properties, and ESI‐Mass Spectra

Abstract Five niobium cluster compounds of the AI2[Nb6Cl18] type (AI = organic cation: [nPr4N]+, [nBu4N]+, [BMIm]+, [Ph4P]+, and [PPN]+) are obtained through treatment of [Nb6Cl14(H2O)4]·4H2O with excess of thionyl chloride in the presence of an organic chloride, AICl. Single‐crystal structure studies show that the compounds consist of discrete cations and cluster [Nb6Cl18]2– anions. The cluster unit of the hydrated cluster starting material is oxidized by two electrons. Powder diffraction studies and NMR spectroscopic measurements show all compounds to crystallize without co‐crystallized solvent molecules. They are air and water stable. The solubility in organic solvents changes to a great extent on changing the type of cation. The ESI‐MS spectra of [nPr4N]2[Nb6Cl18] and [Ph4P]2[Nb6Cl18] show the pseudomolecular peak of the anionic cluster as well as additional signals, which involve simultaneously chloride mass loss and reduction processes.

ChemInform Abstract: Rhodium‐Catalyzed Benzylic Fluorination of Trichloroacetimidates.

AbstractThe reaction is performed starting from 2‐naphthyl, phenyl, and 3‐pyridyl substituted trichloroacetamidates.

Cyanato- and thiocyanato-substituted triangular clusters of molybdenum, [Mo3S4(dppe)3X3]+ (X = NCO−, NCS−; dppe = 1,2-bis(diphenylphosphino)ethane)

Two pseudohalido-substituted cluster complexes, [Mo3S4(dppe)3(NCS)3]NCS (1) and [Mo3S4(dppe)3(NCO)3]Br (2) (dppe = 1,2-bis(diphenylphosphino)ethane), have been synthesized by substitution between [Mo3S4(dppe)3Br3]Br and potassium thiocyanate or sodium cyanate, respectively, in boiling acetonitrile. The compounds were characterized by IR-spectroscopy, elemental analysis, electrospray mass-spectrometry, and single-crystal X-ray diffraction analysis. Both compounds crystallize as toluene solvates (1·3C6H5CH3 and 2·2.5C6H5CH3) in space group with similar unit cell dimensions and adopt very similar molecular geometries. Both structures consist of discrete cluster cations [Mo3S4(dppe)3X3]+, NCS− or Br− anions, and solvate toluene molecules.

Two ammonium tetrachloridoaluminate salts: how a twinned orthorhombic structure emulates a trigonal crystal system.

We have determined the crystal structures of two tetrachloridoaluminate salts. Tetrabutylammonium tetrachloridoaluminate benzene hemisolvate, (C16H36N)[AlCl4]·0.5C6H6, (I), crystallizes with discrete cations, anions and solvent molecules. The benzene molecule is located on a centre of inversion. The structure of the benzene-free polymorph has been determined previously. Tetraethylammonium tetrachloridoaluminate, (C8H20N)[AlCl4], (II), also crystallizes with discrete cations and anions, and forms crystals which appear trigonal but are actually orthorhombic. With the additional reflections of the second and third domains of this nonmerohedral twin, a trigonal lattice is emulated, although the correct crystal system is orthorhombic.

Structural Variation in Mellitate Complexes of First-Row Transition Metals: What Chance for Design?

Eight compounds of Co, Ni, and Cu with mellitate ligands display a wide variety of structures with metal–mellitate coordination polymer dimensionality 0–3. Usually mellitate is fully deprotonated (mel6–), but there is one example of Hmel5– and one of H2mel4–. [M3(mel)(OH2)12]·6H2O (M = Co or Ni) are chain polymers with octahedral M, while [Cu7(OH2)19(OH)2(mel)2]·9H2O has a 2D polymer sheet structure with square-based pyramidal Cu. Addition of KOH produces different compounds. Two incorporate K+ in the structures: K+2(OH2)5[{Ni(OH2)5}2(mel)]2–·2H2O contains discrete nickel–mellitate anionic units, and K+2(OH2)6[{Cu(OH2)3}2(mel)]2–·H2O has a copper–mellitate two-dimensional (2D) polymeric anion. For Co the product is [Co(OH2)6]2+[{Co(OH2)4}5(mel)2]2–·4H2O, with a 2D polymeric anion and discrete cations. A gel-supported synthesis leads to [Cu3(OH2)10(Hmel)][Cu2(OH2)6(Hmel)]·7H2O, with two different copper–mellitate polymeric sheets arranged alternately in a stack. [{Cu(OH2)(EtOH)(4,4′-bipy)}2(H2mel)] contain...

Crystal structure and hydrogen bonded network of new cadmium hybrid complex

Cadmium complexes exhibit extensive potential applications in many fields, such as magnetism materials, biological active materials, optical device and catalysis materials [1]. The reported compound [Tetrakis(5-amino-3-carboxy-1H-1,2,4-triazol-4-ium) hexachloridocadmate (II) tetrahydrate (1) ] was prepared as part of our ongoing investigations of hydrogen-bonding interactions in the crystal structures of metal-protonated N-aromatic heterocyclic hybrid frameworks [2]. 5-Amino-1H-1,2,4-triazole-3-carboxylic acid arises as a promising ligand which can be employed in the preparation of coordination compounds as a consequence of its multiple buildings sites and its basic nitrogen capable of associating with a proton H+ in acid solution [3]. The single-crystal X-ray structure analysis revealed that (1) crystallizes in the monoclinic P-1 space group, the Cd(II) atom is located at a crystallographic inversion centre. The latter ion is octahedrally coordinated by six chloride anions, Due to the presence of a considerable number of proton donors and acceptors, the crystal structure is rich in hydrogen bonding interactions which led to the formation of discrete cation layers spaced by hexachloridocadmate anions. Examination of the cation-anion interactions reveals that N–H...Cl hydrogen bonding are the major packing interactions, It appears that the layered structure results from the octahedral [CdCl6]2- anions along with its ability to form hydrogen bonds in different directions, intermolecular hydrogen bonding interactions between the chloride atom and oxygen atoms of water molecules interconnect the layers into a three-dimensional framework.