Perchlorate Counterions Research Articles

(μ-Diphenylphosphanido-κ2 P:P′)bis[2,2′-(pyridine-2,6-diyl)diphenyl-κ3 C 1,N,C 1′)gold(III)] perchlorate acetonitrile solvate

The title complex, [Au2(C17H11N)2(C12H10P)]ClO4·C2H3N, contains two AuIII atoms bridged by a diphenyl­phosphanide ligand. Each Au atom is in a square-planar environment coordinated by diphenyl­phosphanide and 2,6-diphenyl­pyridine ligands. There are weak π–π stacking inter­actions between neighbouring mol­ecules (the inter­planar separations between two neighbouring dpp units are 3.40 and 3.57 Å). The intra­molecular Au⋯Au separation is 3.788 (5) Å. The crystal structure shows weak inter­molecular C—H⋯O and C—H⋯N hydrogen bonds involving an O atom of the perchlorate counter-ion and the N atom of the acetonitrile solvent mol­ecule, respectively.

A DFT study on the interactions between the [Pt(H 2O)(terpy)] 2+ cation and the triflate and perchlorate counter-anions

The results of DFT B3PW91 calculations on the [(terpy)Pt(OH 2⋯X)] + and [(terpy)Pt(OH 2⋯S)] 2+ {terpy = 2,2′:6′,2″-terpyridine; X = ClO 4, SO 3CF 3; S = CH 3NO 2} models, carried out in order to evaluate the different interaction energy of the [Pt(H 2O)(terpy)] 2+ cation with SO 3 CF 3 - and ClO 4 - counter-anions, as well as with nitromethane, are reported. The computational results likely fit the previously reported X-ray and NMR data on the [Pt(H 2O)(terpy)]X 2 {X = ClO 4, SO 3CF 3} species [G. Annibale, P. Bergamini, V. Bertolasi, M. Bortoluzzi, M. Cattabriga, B. Pitteri, Eur. J. Inorg. Chem. (2007) 5743].

Synthesis and properties of (2-pyridyl)alkylamine- and (2-pyridyl)alkylamine–amide-coordinated copper(II) complexes: Structures and non-covalent interactions

Reaction of the ligand N-methyl- N-((6-pivaloylamido-2-pyridyl)methyl)- N-(2-pyridylethyl)amine (mpppa) with equimolar amounts of [Cu(H 2O) 6][ClO 4] 2 or CuCl 2 · 2H 2O in MeCN afforded mononuclear copper(II) complexes [Cu(mpppa)][ClO 4] 2 ( 1) and [Cu(mpppa)Cl 2] ( 2). Crystal structure analysis reveals CuN 3O (two pyridyl, an aliphatic amine, and an amide oxygen) coordination in 1 and CuN 3Cl 2 (two pyridyl, an aliphatic amine, and two chlorides) coordination in 2. Crystal packing diagram of 1 reveals that one of the perchlorate counteranions provides weak coordination to copper(II) centers and in turn the copper(II) centers assume pseudo-six-coordination, generating 1D chain. Notably, one of the copper(II)-coordinated chloride ions in 2 participates in an intramolecular N–H⋯Cl interaction. Intermolecular C–H⋯Cl interactions in the solid state generate helical structure. Spectroscopic (IR, UV–Vis, and EPR) and redox properties of the two complexes have been investigated and compared.

{Tris[2-(imidazol-2-ylmethyl-imino)eth-yl]methyl-ammonium}iron(II) tris-(per-chlorate) dihydrate.

The title complex, [Fe(C19H27N10)](ClO4)3·2H2O, is a new polymorph of an iron(II) Schiff base complex of tris­(2-amino­ethyl)methyl­ammonium with imidazole-2-carboxaldehyde. The octa­hedral FeII atom is bound to three facial imidazole N atoms with average Fe—Nimidazole and Fe—Nimine bond distances of 1.963 (5) and 1.951 (5) Å, respectively. The central N atom of the tripodal ligand is outside the bonding distance at 3.92 Å. The crystal packing is stabilized by the hydrogen-bonding inter­actions between the two water mol­ecules (acceptor) and two of the three imidazole NH groups (donor). The third imidazole NH group (donor) forms a hydrogen bond to one of the three perchlorate counter-ions (acceptor).

Meta-Phenylene-bridged double Schiff base copper(II) complexes as building blocks for 1D coordination polymers: Synthesis, crystal structure and magnetic properties

The new double Schiff-base ligands H 6ipa-hyhb and H 6ipa-hyhh were synthesized by condensation of a 4,6-diformylresorcinol derivative (ipa) with 4-hydroxy-butanoic acid hydrazide (hyhb) and 6-hydroxy-hexanoic acid hydrazide (hyhh). The reaction with copper(II) perchlorate in the presence of an appropriate co-ligand (Him = imidazole, Hpz = pyrazole) leads to the novel coordination polymers {[Cu 2(H 4ipa-hyhb)(Hpz) 2](ClO 4) 2} n ( 1), {[Cu 2(H 4ipa-hyhb)(Him) 2](ClO 4) 2} n ( 2), and {[Cu 2-(H 4ipa-hyhh)(Hpz) 2](ClO 4) 2} n ( 3). These coordination polymers are composed of primary building blocks with the general formula [Cu 2(H 4ipa-X)(L) 2] 2+ (X = hyhb, hyhh; L = Him, Hpz) which are linked by coordination of the hydroxyl groups of the ligand side chains at the apical position of copper(II) centers of adjacent building blocks. The resulting chains possess different topologies and therefore different supramolecular structures due to the variation in length of the ligand alkyl side chains. For the complexes 1 and 2 double hydroxyalkyl-bridged distorted ladder like chains are formed. Whereas in case of complex 3 single hydroxyalkyl-bridged chains are obtained which assemble to hydrogen bonded double chains. In the case of 1 and 2 these chains are cross-linked by hydrogen bonding interactions with the perchlorate counterions, whereas for 3 additional π–π stacking interaction are observed. The temperature-dependent magnetic measurements indicate weak antiferromagnetic interactions with coupling constants J = −26.1 cm −1 ( 1), J = −28.2 cm −1 ( 2), and J = −26.5 cm −1 ( 3). The magnetic exchange interaction is solely the result of a coupling within the dinuclear complex moieties through the central resorcinol moiety.

Di-μ-hydroxido-bis{[bis(6-methyl-2-pyridylmethyl)(2-phenylethyl)amine-κ3N′,N′′,N′′′]copper(II)} bis(perchlorate)

The title compund, [Cu(2)(OH)(2)(C(22)H(25)N(3))(2)](ClO(4))(2), is a copper(II) dimer, with two [CuL](2+) units [L is bis(6-methyl-2-pyridylmethyl)(2-phenylethyl)amine] bridged by hydroxide groups to define the {[CuL](mu-OH)(2)[CuL]}(2+) cation. Charge balance is provided by perchlorate counter-anions. The cation has a crystallographic inversion centre halfway between the Cu(II) ions, which are separated by 3.0161 (8) Angstrom. The central core of the cation is an almost regular Cu(2)O(2) parallelogram of sides 1.931 (2) and 1.935 (2) Angstrom, with a Cu-O-Cu angle of 102.55 (11) degrees . The coordination geometry around each Cu(II) centre can be best described as a square-based pyramid, with three N atoms from L ligands and two hydroxide O atoms completing the coordination environment. Each cationic unit is hydrogen bonded to two perchlorate anions by means of hydroxide-perchlorate O-H...O interactions.

Synthesis, characterization, electrochemical and spectroscopic investigation of cobalt(III) Schiff base complexes with axial amine ligands: The layered crystal structure of [Co III(salophen)(4-picoline) 2]ClO 4 · CH 2Cl 2

Cobalt(III) complexes with potentially tetradentate salophen (H 2salophen = N, N′–bis(salicylidene)-1,2-phenylenediamine) as equatorial ligand and with different axial amine ligands (NH 3, cyclohexylamine, aniline, 4-picoline and pyridine) were synthesized and characterized by IR, 1H NMR, elemental analysis. Electronic spectra and electrochemical properties of the complexes were studied in DMF solutions. The lowest energy transitions, which occur between 464.8 and 477 nm, are attributed mainly to the intraligand charge transfer, confirmed by Zindo/S electronic structure calculations. The reduction potentials of Co(III)/Co(II) are more affected than those of Co(II)/Co(I) by the axial amine ligands. The crystal structure of the [Co III(salophen)(4- picoline) 2]ClO 4 · CH 2Cl 2 was determined, indicating that the cobalt(III) center is six coordinated surrounded by the tetradentate salophen ligand and two 4-picoline ligands. The crystal packing of the complex shows a layered structure, in which the perchlorate counter ions and also the lattice solvent molecules are intercalated between the bc planes of the complex cations.

Bis{N-[bis(6-bromopyridin-2-yl)methylene-κN]ethane-1,2-diamine-κ2N,N′}nickel(II) bis(perchlorate)

In the title compound, [Ni(C13H12Br2N4)2](ClO4)2, the cationic monomeric complex has a ligand–metal ratio of 2:1, with the NiII atom lying at the centre of a distorted octa­hedral geometry. The cation is surrounded by six nitro­gen donors of two tridentate ligands, and the cationic character of the group is balanced by two perchlorate counter-ions per formula unit.

Coordination chemistry of 1,4-bis(carboxymethyl)-1,4,7-triazacyclononane: Synthesis and characterization of mononuclear and binuclear μ-oxo-bridged iron(III) complexes, and a 1D-helical copper(II) chain

The syntheses of the pentadentate ligand 1,4-bis(carboxymethyl)-1,4,7-triazacyclononane ( LH 2) and its use in the preparation of [LHCu]ClO 4 ( 1), and a mononuclear iron(III) complex ([LFeCl] (2)) are reported. The hydrolysis of 2 in the presence of an excess of NaClO 4 resulted in the crystallization of a binuclear complex, [Fe 2(μ-O)L 2] · (NaClO 4) 3 · CH 3OH · 3H 2O (3). The crystal structures of 1– 3 have been determined by single-crystal X-ray crystallography. In complex 1, the Cu(II) centre is in square based pyramidal environment, with two nitrogen atoms from the tacn ring and two oxygen atoms from two different carboxylate groups lying in the basal plane and the third nitrogen atom occupying the apical position. One pendant acetic acid group is protonated and, instead of coordinating to the copper(II) centre, participates in hydrogen bonding interactions with the perchlorate counter-ion. The coordinated carboxylate group forms a bridge to the copper atom of an adjacent [LHCu] + molecule, thus generating 1D-helical chains. The compound exhibits weak ferromagnetic coupling probably due to weak interactions between [LHCu] + molecules. In complex 2, the iron(III) centre is in a distorted octahedral geometry, with the fac-coordinated triamine ring, two carboxylate groups and one chloride ligand occupying the coordination sphere. In the binuclear complex 3, two iron(III) centres are bridged by one oxygen atom to form a μ-oxo-diiron(III) complex with an Fe⋯Fe distance of 3.423(3) Å and a non-linear Fe–O–Fe angle of 144.4°. This binuclear complex features strong antiferromagnetic coupling between the two iron(III) centres.

Recognition of Thymine and Related Nucleosides by a ZnII-Cyclen Complex Bearing a Ferrocenyl Pendant

A cyclen derivative bearing a ferrocenyl arm (L) and a series of its ZnII complexes [ZnL(OH2)][ClO4]2 (C1), [ZnL(OH)][ClO4] (C2), and [ZnL(Cl)][ClO4].CH3CN (C3) (cyclen = 1,4,7,10-tetraazacyclododecane, L = 1-(ferrocenemethyl)-1,4,7,10-tetraazacyclododecane) have been prepared and characterized spectroscopically. An X-ray structure determination confirmed the formation of complex C1 and revealed that the coordinated water participates in hydrogen bonding with the perchlorate counter ions. The pKa value for deprotonation of the water molecule determined by potentiometric titration was found to be 7.36 +/- 0.09 at 25 degrees C and I = 0.1 (KNO3). The possibility of using complex C1 as a potential sensor for thymine derivatives in aqueous solution has been examined. Shifts in the 1H and 13C NMR resonances showed the binding occurred with thymine (T) and two thymine derivatives, thymidine (dT) and thymidine 5'-monophosphate (TMP2-). Significant shifts of the nuC=O and nuC=C vibrations of the thymine derivatives were also observed via IR spectroscopy upon complexation with the receptor. The thymine adduct, [ZnL(thymine anion)][ClO4].2H2O (C4), has been crystallized and characterized. The X-ray structure of C4 confirmed the thymine binding to the receptor, and the short Zn-N(thymine) distance of 1.975(5) A indicated clearly that the ferrocenyl arm does not affect the complexation of the DNA base. In contrast to the large spectral changes, electrochemical studies showed a small shift of the reversible potential of the redox couple Fc+/Fc (Fc = ferrocene) and subtle changes in voltammetry upon the addition of an excess of dT, TMP2-, and guanine (dG) at physiological pH, indicating the level of interaction is similar in both Fc and Fc+ forms.

Oxalato‐Bridged Dinuclear Copper(II) Complexes of N‐Alkylated Derivatives of 1,4,7‐Triazacyclononane: Synthesis, X‐ray Crystal Structures and Magnetic Properties

AbstractThe synthesis, X‐ray crystal structure and magnetic properties of two oxalato‐bridged dinuclear CuII complexes, [L‐Cu(μ‐ox)Cu‐L](ClO4)2, where ox = oxalate and L = 1,4,7‐trimethyl‐1,4,7‐triazacyclononane (Me3tacn) or 1‐benzyl‐4,7‐dimethyl‐1,4,7‐triazacyclononane (BzMe2tacn) are reported, as well as the X‐ray crystal structure of the mononuclear complex, [Cu(Me3tacn)(OH2)2](ClO4)2, which features an extended H‐bonding network between the ligand and the perchlorate counterions. The crystal structures of the dinuclear complexes both feature a centrosymmetric complex cation in which the two copper centres exist in a distorted square‐pyramidal geometry, with each end capped by a facially coordinated “tacn” unit, and are bridged by an oxalate anion. Variable‐temperature magnetic susceptibility measurements revealed strong antiferromagnetic interactions between the CuII centres, with 2J values of ca. –300 cm–1, even though the Cu···Cu separation is very long, viz. 5.18 Å (BzMe2tacn) and 5.47 Å (Me3tacn). The separation for the Me3tacn complex is the longest separation reported for this type of CuII complex. No pattern could be detected between the J values and structural features for 21 oxalato‐bridged complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

(Acetonitrile-κN){2-[bis(2-pyridylethyl)amino]ethanol-κ4N,N′,N′′,O}zinc(II) bis(perchlorate) monohydrate

In the title compound, [Zn(C2H3N)(C16H21N3O)](ClO4)2.H2O, the Zn(II) ion is coordinated by two pyridyl N atoms, one amine N atom, and an ethanol O atom from the N,N',N'',O-tetradentate 2-[bis(2-pyridylethyl)amino]ethanol donor ligand. The fifth coordination site is filled by an acetonitrile N atom, and there is one solvent water molecule in the asymmetric unit. The 2+ charge of the cationic portion of the complex is balanced by two perchlorate counter-anions.

Coordination Chemistry of Acrylamide. 5. Crystal Structures of Complexes of Metal(II) Perchlorates and Tetrafluoroborates with Acrylamide

AbstractAcrylamide complexes of metal perchlorates and tetrafluoroborates, [M(OC(NH2)CH=CH2)6][X]2 (M = Fe, Co, Ni, Zn; X = ClO4, BF4), have been prepared and characterized using single crystal X‐ray diffraction, IR spectroscopy and elemental analyses. The complexes contain metal(II) cations surrounded by an octahedral array of acrylamide ligands accompanied by the anions. The tetrafluoroborate or perchlorate counter anions do not coordinate to the metal atoms or take part in strong secondary interactions such as hydrogen bonds with coordinated ligands. Single crystal X‐ray structures of these complexes prove that the ligands are coordinated exclusively via the carbonyl oxygen atom. Bonding through the nitrogen atom has not been observed in these complexes.

Bis(3-aminopyridine-κN)(4,4′-dimethyl-2,2′-bipyridine-κ2N,N′)(perchlorato-κO)copper(II) perchlorate

The title compound, [Cu(ClO 4 )(C 5 H 6 N 2 ) 2 (C 12 H 12 N 2 )]ClO 4 , was prepared by in situ partial ligand substitution between 3-aminopyridine and 4,4'-dimethyl-2,2'-bipyridine at room temperature. The central copper(II) ion is five-coordinated by one bidentate 4,4'-dimethyl-2,2'-bipyridine molecule, two monodentate pyridine-coordinated 3-aminopyridine molecules and one apical O atom from the perchlorate counterion. Intermolecular N-H···O and C-H···O hydrogen-bonding interactions form a hydrogen-bond-sustained network.

Bis(2,2′-bipyridine)[2-(2-pyridyl)-1H-benzimidazol-1-yl]ruthenium(II) perchlorate acetonitrile solvate monohydrate

The title complex, [Ru(C12H8N3)(C10H8N2)2]ClO4·CH3CN·H2O, was grown by diethyl ether diffusion into an acetonitrile solutionfrom acetonitrile at room temperature. The RuII ion is in a distorted octa­hedral environment coordinated by two 2,2′-bipyridine (bpy) and one deprotonated 2-(2-pyrid­yl)benz­imidazole (PIB) ligand. Charge is balanced by a perchlorate counter-ion. The free water mol­ecule links an O atom of the perchlorate ion and the uncoordinated N atom of the ligand PIB by hydrogen bond.

Mononuclear and Dinuclear Copper(I) Complexes of Bis(3,5-dimethylpyrazol-1-yl)methane: Synthesis, Structure, and Reactivity

The synthesis and structures of a mononuclear copper(I) carbonyl complex [Cu(OClO3)(CO)(H2CPz2')] (3) and a dinuclear copper(I) carbonyl complex [{Cu(CO)(H2CPz2')}2(mu-pyrazine)](ClO4)2 (4), where H2CPz2' = bis(3,5-dimethylpyrazol-1-yl)methane, are described. These two compounds were generated by the carbonylation of the corresponding copper(I)-acetonitrile complexes, [Cu(H2CPz2')(MeCN)](ClO4) (1) and [{Cu(H2CPz2')(MeCN)}2(mu-pyrazine)](ClO4)2 (2). Alternatively, treatment of mononuclear 1 and 3, respectively, with pyrazine in a molar ratio of 2:1 produces the pyrazine-bridged dinuclear Cu(I) complexes 2 and 4. Each of the complexes 1-4 can react with PPh3 to generate a common three-coordinated copper(I) complex [Cu(PPh3)(H2CPz2')](ClO4) (5). The structures of complexes 1-5 were all confirmed by X-ray crystallography. Comparison of the Cu(I)-C(CO) bond distances and the CO stretching frequencies of 3 and 4 indicates the back-donating properties of d pi(Cu)-pi*(pyrazine) bonds in 4, and accordingly, stabilizes the mixed-valence species generated from 2. Complex 3, stabilized by the strong interaction between copper(I) ion and perchlorate counteranion (Cu(I)-O(ClO4) = 2.240(3) A), is a potential precursor for polynuclear copper(I) carbonyl complexes.

Tris({2-[(1-methylimidazol-2-yl)methylimino]ethyl}amine)cobalt(II) diperchlorate

The CoII atom of the title complex, [Co(C21H30N10)](ClO4)2, located on a threefold rotation axis, is coordinated in an octahedral geometry by three imine N atoms and the three imidazole N atoms, with Co—N distance of 2.131 (3)–2.164 (3) A, and cis and trans N—Co—N angles of 76.17 (12)–102.77 (10) and 163.66 (12)°, respectively. The perchlorate counter-anions are located on centers of symmetry.

Trans-Bis[4-(4-methylphenyl)-3,5-di-2-pyridyl-4H-1,2,4-triazole]diperchlorato-κ2O-copper(II)

In the title centrosymmetric mononuclear copper(II) compound, [Cu(ClO4)2(C19H15N5)2], the central CuII atom is coordinated by four N atoms from two 4-(4-methyl­phenyl)-3,5-di-2-pyridyl-4H-1,2,4-triazole ligands, and two O atoms from two perchlorate counter-ions. The coordination geometry is slightly distorted octahedral.

Exchange coupling in µ-aqua:µ-oxo vs. di-µ-hydroxo dinuclear Cu(ii) compounds: a density functional study

Theoretical methods based on density functional theory have been applied to study the differences in exchange coupling between the di-mu-hydroxo and mu-aqua:mu-oxo tautomers of a dinuclear Cu(II) complex. The calculations indicate that the two compounds are totally different from a magnetic point of view. The transfer of one proton from one of the two hydroxo bridges to the other leaves an asymmetric structure with only one effective exchange pathway through the oxo bridge. The coordinated water molecule and an associated perchlorate counterion, although not directly involved in the exchange coupling, play an important role in the magnetic properties of this compound since their presence is crucial in the determination of the geometrical details of the Cu-O(ox)-Cu linkage and hence in the exchange coupling between the copper atoms.

Monoalkylated 4′‐Aryl‐Substituted Terpyridines

AbstractFor Abstract see ChemInform Abstract in Full Text.