Perchlorate Oxygen Atoms Research Articles

Crystal Structure, Magnetic Properties, and Electrical Characterization of a New Coordination Compound: [CuClO4(C4H6N2O)4H2O]ClO4(C4H6N2O)0.08

The chemical preparation and characterization of a novel coordination compound [CuClO4(C4H6N2O)4H2O]ClO4(C4H6N2O)0.08 is reported. The compound crystallizes in the monoclinic space group P21/c with lattice parameters a = 11.2678(5) A, b = 12.8102(6) A, c = 19.7250(8) A, β = 100.3051(15)°, V = 2801.2(2) A3. The Cu(II) cation is six-coordinated in an elongated distorted octahedral fashion by four N atoms of four 3-amino-5-methylisoxazole ligands, one water oxygen atom, and one perchlorate oxygen atom. In the atomic arrangement, the coordinated and uncoordinated perchlorate anions are grouped in pairs to form anionic layers parallel to the (a, b) plane. A substantial number of H-bonding interactions leads to the formation of an intricate three-dimensional network. The vibrational absorption bands are identified by infrared spectroscopy and the electrical properties are studied by impedance spectroscopy. The DSC analysis agrees with the electrical conductivity results. Magnetic properties are also determined to characterize the complex.

A new tetraiminodiphenol macrocyclic ligand and its two dicopper(II) complexes: Syntheses, crystal structures, electrochemistry and magnetochemistry

This paper deals with the diprotonated salt, [H4L](ClO4)2 (1), of the tetraiminodiphenolate macrocyclic ligand, H2L which is the [2+2] condensation product of 4-ethyl-2,6-diformylphenol and 2,2′-dimethyl-1,3-diaminopropane, and two diphenoxo-bridged dicopper(II) complexes [Cu2L(ClO4)2] (2) and [Cu2L(ClO4)](ClO4) (3). The syntheses, characterization and crystal structures of 1–3 and the magnetic and electrochemical properties of the metal complexes 2 and 3 are presented. The cationic macrocycle [H4L]2+ is stabilized by four intramolecular and symmetric NH…O…HN hydrogen bonds involving phenoxo oxygen and imino nitrogen atoms. One metal center in 3 is tetracoordinated and in a square planar geometry. The second metal ion of 3 and both the metal ions in 2 are pentacoordinated and in a square pyramidal geometry; one perchlorate oxygen atom occupies the apical position in each case. Both 2 and 3 exhibit quasireversible two-step one-electron couples in the reduction window. The E½ (ΔEp) values (in mV) for the CuIICuII/CuIICuI couple is −0.466V (0.067V) for 2 and −0.490V (0.076V) for 3, while the E½ (ΔEp) values (in mV) for the CuIICuI/CuICuI couple is −0.953V (0.060V) for 2 and −0.985V (0.069V) for 3. Variable-temperature (2–300K) magnetic susceptibility measurements of the two compounds reveal that the metal centers in both of the complexes are coupled by strong antiferromagnetic interactions with 2J values (H=−JS1·S2) of −780 and −820cm−1 for 2 and 3, respectively.

Synthesis and Crystal Structure of a Binuclear Manganese(II) Ternary Complex Derived From N-(2- pyridylmethylidene)taurine and 1,10-Phenanthroline

The title compound, 1, with the formula [Mn2(pmt)2(1,10-phen)2].2ClO4 [N-(2-pyridylmethylidene)taurine (abbreviated as pmt), consists of a structurally centrosymmetric dinuclear MnII complex and two discrete perchlorate anions. Each Mn center is six-coordinated with an N4O2 donors set of the pmt and 1,10-phenanthorline ligands, resulting in a compressed octahedral. In the crystal packing, the component cations interact with pairs of intermolecular C-H···O and π-π contacts forming a 2-D network. Also, the neighboring 2-D cationic layers are connected to each other with C–H···O interactions of perchlorate oxygen atoms with the separate C···O distances of 3.204(7)-3.365(8) Å, giving a supramolecular 3-D network. [Supplemental materials are available for this article. Go to the publisher's online edition of Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry to view the supplemental file.]

Structural, spectroscopic, and electrochemical properties of two mononuclear iron(III) complexes derived from a tetraiminodiphenolate ligand

Two iron(III) mononuclear complexes [Fe(LH 2)(H 2O) 2](ClO 4) 3·3H 2O ( 1) and [Fe(LH 2)(H 2O)Cl](ClO 4) 2·2H 2O ( 2) have been prepared using [Pb(LH 2)](ClO 4) 2 and Fe(ClO 4) 3·6H 2O and FeCl 3·6H 2O for 1 and 2, respectively. LH 2 refers to the macrocyclic Schiff base ligand derived from the condensation of 1,3-diaminopropane and 4-methyl-2,6-diformyl phenol. Complex 1 crystallizes in the space group Orthorhombic Pnma. Complex 1 shows extensive intra- and intermolecular hydrogen bonding involving the iron coordinated water molecules, perchlorate oxygens and the water of crystallization. Seven symmetry-related intermolecular O–H⋯O bonds in 1 form a remarkable two dimensional network of water channels. Complex 2 crystallized in Monoclinic P2 1/ c space group, with two [Fe(LH 2)(H 2O)Cl](ClO 4) 2 units forming a dimeric structure in the unit cell. Iron coordinated chloride, water of crystallization and perchlorate oxygen atoms display a strong network of hydrogen bonds responsible for holding the two mononuclear units together. Electrochemical experiments revealed a facile reduction of 1 in 10:1 acetonitrile–water with E 1/2 = 140 mV while addition of 8-fold excess of tetramethylammonium chloride afforded [Fe(LH 2)Cl 2] + which got reduced at E 1/2 = −80 mV.

Coordination Chemistry of Mercury(II) in Liquid and Aqueous Ammonia Solution and the Crystal Structure of Tetraamminemercury(II) Perchlorate

The ammonia solvated mercury(II) ion has been structurally characterized in solution by means of EXAFS, (199)Hg NMR, and Raman spectroscopy and in solid solvates by combining results from X-ray single crystal and powder diffraction, thermogravimetry, differential scanning calorimetry, EXAFS, and Raman spectroscopy. Crystalline tetraamminemercury(II) perchlorate, [Hg(NH3)4](ClO4)2, precipitates from both liquid ammonia and aqueous ammonia solution, containing tetraamminemercury(II) complexes. The orthorhombic space group ( Pnma) imposes C s symmetry on the tetraamminemercury(II) complexes, which is lost at a phase transition at about 220 K. The Hg-N bond distances are 2.175(14), 2.255(16), and 2 x 2.277(9) A, with a wide N-Hg-N angle between the two shortest Hg-N bonds, 122.1(7) degrees , at ambient temperature. A similar distorted tetrahedral coordination geometry is maintained in liquid ammonia and aqueous ammonia solutions with the mean Hg-N bond distances 2.225(12) and 2.226(6) A, respectively. When heated to 400 K the solid tetraamminemercury(II) perchlorate decomposes to diamminemercury(II) perchlorate, [Hg(NH3)2](ClO4)2, with the mean Hg-N bond distance 2.055(6) A in a linear N-Hg-N unit. The mercury atoms in the latter compound form a tetrahedral network, connected by perchlorate oxygen atoms, with the closest Hg...Hg distance being 3.420(3) A. The preferential solvation and coordination changes of the mercury(II) ion in aqueous ammonia, by varying the total NH 3:Hg(II) mole ratio from 0 to 130, were followed by (199)Hg NMR. Solid [Hg(NH 3)4](ClO4)2 precipitates while [Hg(H2O)6](2+) ions remain in solution at mole ratios below 3-4, while at high mole ratios, [Hg(NH3)4](2+) complexes dominate in solution. The principal bands in the vibrational spectrum of the [Hg(NH3)4](2+) complex have been assigned.

(m-Phenylenedimethylene)diammoniump-nitrophenylphosphate perchlorate

The title compound, C8H14N2 2+·C12H8N2O8P−·ClO4 −, was formed by the reaction of α,α-bis-m-xylenediamine and sodium bis-p-nitro­phenyl­phosphate in the presence of Zn(ClO4)·6H2O in methanol solution. The two amine groups of the m-xylenediammonium ion are each protonated and each hydrogen-bonded to two O atoms of the phosphate anion, which acts as a 1,3-bridge. The ammonium groups are arranged matched face to face and each pair is doubly bridged by two perchlorate ions through hydrogen bonding. In addition, there are also weak C—H⋯O inter­actions. Both the N—H⋯O and C—H⋯O inter­actions are contained in a channel down the a axis. The perchlorate oxygen atoms are disordered over two positions with site occupancy factors of ca 0.7 and 0.3.

Synthesis and characterization of mononuclear copper(II) and cadmium(II) complexes with di-(2-picolyl)sulfur

The reaction of Cu(ClO4)2·6H2O and Cd(ClO4)2 with di-(2-picolyl)sulfur (dps) leads to the formation of mononuclear complexes [Cu(dps)(H2O)(ClO4)](ClO4) (1) and [Cd(dps)2](ClO4)2 (2). The crystal structure of 1 exhibits a distorted square pyramidal geometry, coordinated by one sulfur and two nitrogen atoms from the dps ligand, one water molecule and one perchlorate oxygen atom. For 2, the environment around cadmium atom is in a distorted octahedron with four nitrogen and two sulfur atoms from the dps ligand. Cyclic voltammetric data show that complexes undergo two waves of a one-electron transfer corresponding to M(II)/M(III) and M(II)/M(I) processes. Spectral and electrochemical behaviors of the complexes are also discussed.

Supramolecular assemblies prepared from an iron(ii) tripodal imidazole complex. A molecular scaffolding for the self assembly of icosahedral complexes of K+, Rb+, Cs+ and NH4+ cations

The iron(II) complex of the 1 : 3 Schiff base condensate of tris(2-aminoethyl)amine (tren) with 2-imidazolecarboxaldehyde, H3L1, [FeH3L1](ClO4)2, was reacted with MClO4 (M = K, Rb, Cs, and NH4). The products were double salts of the formula {[FeH3L1](ClO4)2}·MClO4. The complexes have been characterized by Elemental Analysis, X-ray crystallography, ESMS, IR and Mossbauer spectroscopy. The resultant complexes are all trigonal, crystallize in P and exhibit a hexameric structure in the extended lattice. The cations are located at the origin (0, 0, 0) and c/2 (0, 0, 0.5) on the c axis. The cations are twelve coordinate and exhibit a distorted icosahedral geometry formed by six bidentate perchlorate anions. The perchlorate anions are involved in extensive hydrogen bonding with the iron complexes, which are located at the vertices of the hexagon. Each perchlorate anion has five hydrogen bonds to three iron complexes. The iron complexes use the imidazole NH and imine NCH as donors to the perchlorate oxygen atoms. The imidazole NH is a trifurcated donor and the imine CH is a bifurcated donor. The formation of the double salt and the accompanying hydrogen bonding results in a shift in the spin equilibrium of the parent iron(II) complex from 63% high spin, HS, and 37% low spin, LS, at 295 K to pure LS in the double salts. Attempts to incorporate sodium or silver in the above salts failed due to their size and oxidizing strength, respectively. The analogous manganese complex, [MnH3L1](ClO4)2, failed to give these double salts under identical reaction conditions. The lack of reactivity of [MnH3L1](ClO4)2 does not appear to be due to its solubility or geometric considerations of the hydrogen bonding donor site, but instead to the electronic differences between the high spin [MnH3L1](ClO4)2 and the spin crossover [FeH3L1](ClO4)2.

Compounds of some alkylamido-substituted cyclic tetraamines with copper(II): The structure of di(perchlorato) RRSS( trans-(6,13-bis(ethylamido)-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane)copper(II)

The amino substituents of ( trans-6,13-diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane)copper(II) are readily acylated by reaction with acetic or propionic anhydrides to form the 6,13-bismethylamido- (acetylamino-) or 6,13-bis(ethylamido)- (propionylamino-) substituted cations. Centrosymmetrical di(perchlorato-κ 1 O)-( R 1 R 4 S 8 S 11- trans-6,13-bisethylamido-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-κ 4 N 1 N 4 N 8 N 11)copper(II) has copper(II) in square-planar coordination by the endocyclic nitrogen atoms of the macrocycle, Cu–N = 1.996(2), 2.012(2) Å, with perchlorate oxygen atoms axially coordinated, Cu–O = 2.528(2) Å.

Heterodinuclear MIICuII complexes of a constrained macrocyclic compartmental ligand. EPR studies of spin-coupled MnIICuII (ST=2) and NiIICuII (ST=1/2)

A phenol-based macrocyclic compartmental ligand (L)2−, having an N(amine)2O2 metal-binding site with 1,3-trimethylene chain between the two aminic nitrogen atoms and an N(imine)2O2 site with 1,8-naphthalene chain between the two iminic nitrogen atoms, has afforded the following heterodinuclear MIICuII complexes, [MCu(L)(dmf)2](ClO4)2 (M=Mn (1), Co (2), Ni (3), Zn (4)). X-ray crystallographic studies for 1–4 demonstrate that the MII resides in the N(amine)2O2 site and the CuII in the N(imine)2O2 site of the constrained macrocyclic ligand. The MII has a six-coordinate geometry together with two dmf molecules at the axial site and the CuII has a square-pyramidal geometry with a perchlorate oxygen atom at the apical site. Magnetic, visible spectral and electrochemical properties of the complexes are examined. A frozen dmf solution of 1 at liquid nitrogen temperature shows an EPR signal with a Mn hyperfine structure (AMn=103×10−4 cm−1) at ∼2400 Ga, which is attributed to the ST=2 ground state of the spin-coupled MnII (S=5/2)–CuII (S=1/2). A qualitative analysis is made for the EPR of 1 in comparison with the EPR of the ST=1/2 state of spin-coupled NiII (S=1)–CuII (S=1/2) of 3.

Synthesis, Characterization and Crystal Structures of Monomeric and Imidazolate-Bridged Polymeric Copper(II) Complexes of 5-Methyl-1,5,9-triazanonane

Two complexes [Cu(mtan)(H2O)(ClO4)](ClO4) (Im = imidazolate) (1) and [Cu(mtan)(Im)]n (ClO4)2n (mtan = 5-methyl-1,5,9-triazanonane) (2) have been prepared and characterized. Single-crystal X-ray analysis reveals that (1) crystallizes in the orthorhombic space group Pbcm, with a 8.906(5), b 12.255(6), c 14.821(4) Å and V 1618(1) Å3, and complex (2) crystallizes in the orthorhombic space group Pca21, with a 11.125(7), b 9.149(6), c 15.180(7) Å and 1545(1) Å3. The copper(II) atom in complex (1) is in a distorted square-pyramidal geometry, being coordinated by three nitrogen atoms from an mtan ligand and one oxygen atom from an aqua ligand at the basal plane and one perchlorate oxygen atom at the apical position. The structure of complex (2) features polymeric cationic chains composed of [Cu(mtan)(Im)]+ repeating units and discrete perchlorate anions. The Cu(1) atom in each unit has a severely distorted trigonal-bipyramidal geometry, being coordinated by three nitrogen atoms from one mtan ligand and two nitrogen atoms from two Im groups. The structural units are linked by -Im groups to give one-dimensional chains. The variable-temperature magnetic measurement on the powder sample of (2) reveals intrachain, medium antiferromagnetic interaction with g = 2.240 and J = –36.45 cm–1 through the -Im bridges.

Studies of lead(II) complexes of substituted calix[4]diquinones: the remarkable self-assembly of a novel redox-active 3D channel network

Several calix[4]diquinone–lead(II) complexes have been prepared. Two momonomeric complexes have been prepared with p-tert-butyl-(26,28-crown-5)calix[4]diquinone L111 and p-tert-butylcalix[4]diquinone bis(ethyl ether) L222, namely [PbL111(ClO4)2] and [PbL222(ClO4)2(H2O] wherein the metal atoms are 10-coordinate being bonded to the four oxygen atoms at the lower rim of the calixdiquinone and three perchlorate oxygen atoms together with three crown oxygen atoms or two carbonyl oxygen atoms and a water molecule respectively. By contrast the lead(II) complex with calix[4]diquinone bis(acid) L333 forms a unique trimeric [Pb9(L333 − 2H)3(ClO4)6(OH)6] unit with crystallographic 3/m symmetry containing three unique Pb(II) atoms. One of these is to be found within the calix[4]diquinone bonded to the four oxygen atoms at the lower rim, two acid oxygen atoms, two perchlorate anions and a water molecule. The other two Pb(II) atoms are bonded to carbonylic oxygen atoms, water molecules and hydroxide ions. These trimeric units are interconnected via upper rim quinone oxygen–Pb(II) interactions to form a three-dimensional network containing channels of ca. 14 A in diameter.

Synthesis, structures and hydrolytic properties of metal complexes with 1,3-bis[(4-methyl-5-imidazol-1-yl)ethylideneamino]propan-2-ol

Synthesis of a polydentate ligand comprising imidazole donors, 1,3-bis[(4-methyl-5-imidazol-1-yl)ethylideneamino]propan-2-ol (BIPO), and its Zn II ( 1), Mn II ( 2), Ni II ( 3) and Cu II ( 4) complexes are reported. Single-crystal structural analysis shows that complex 1 adopts a distorted square-pyramidal coordination geometry with the basal positions occupied by the four nitrogen atoms of a tetradentate BIPO ligand and the apical position by a water molecule, complexes 2 and 3 exhibit elongated octahedral coordination geometries with the axial positions occupied by a pair of aqua molecules, whereas complex 4 exhibits an elongated octahedral geometry with the axial positions occupied by an aqua molecule and a perchlorate oxygen atom. The crystal structures of the four complexes are discussed in relation to the preference of zinc ion in carbonic anhydrase, and suggest that in the presence of nitrogen donor ligands, Zn II has a significant tendency to form a four- or five-coordination. Hydrolysis of 4-nitrophenyl acetate with complexes 1– 3 shows that the k obs for complexes 1, 2 and 3 were 2.74×10 −2± 0.01, 1.45×10 −2± 0.01 and 0.98×10 −2± 0.01 M −1s −1, respectively.

Syntheses, crystal structures and properties of copper(II) complexes of 1,3-bis (4-methyl-5-imidazol-1-yl)ethylideneamino propan-2-ol and 1,3-bis (4-methyl-5-imidazol-1-yl)ethylideneamino propane

The syntheses of two polydentate ligands comprising imidazole donors, 1,3-bis[(4-methyl-5-imidazol-1-yl) ethylideneamino]propan-2-ol (BIPO), 1,3-bis[(4-methyl-5-imidazol-1-yl)ethylideneamino]propane (BIP), and their copper(II) complexes [Cu(BIPO)(ClO4)(H2O)] (NO3) · H2O (1) and [Cu(BIP)(ClO4)](ClO4) · 2H2O (2) are reported. Single-crystal structural analyses show that (1) adopts an elongated octahedral geometry with the axial positions occupied by a perchlorate oxygen atom and an aqua ligand, while (2) adopts a distorted square-pyramidal geometry with the axial positions occupied by a perchlorate oxygen atom. Electronic spectra in aqueous solution indicate that both (1) and (2) adopt square-pyramidal geometry. Cyclic voltammetry in aqueous solution gives reduction waves at −0.07 and −0.08 V versus s.c.e. for (1) and (2), respectively. The low reduction potential and general reversibility of the redox reaction of (1) and (2) indicate that BIPO and BIP are flexible enough to stabilize both CuII and CuI forms of the complexes.

Synthesis, crystal structures and properties of copper(II) complexes of Schiff base derivatives containing imidazole and β-alanine groups

Four copper(II) complexes with Schiff base ligands N-[(5-methylimidazol-4-yl)methylene]-β-alanine (HL1) and N-[(1-methylimidazol-2-yl)methylene]-β-alanine (HL2) and their reduced forms N-[(5-methylimidazol-4-yl)methyl]-β-alanine (HL3) and N,N-bis[(5-methylimidazol-4-yl)methyl]-β-alanine (HL4) have been synthesized. The crystal structures of [CuL1(H2O)(ClO4)] 1, [CuL2(H2O)(ClO4)] 2, [CuL3(Py)(ClO4)] 3 and [Cu2(L4)2][ClO4]2·2H2O 4 have been determined. Complexes 1 and 2 are structurally very similar, the copper(II) atom being tridentately chelated by the Schiff base using one carboxy oxygen atom and two nitrogen atoms at the equatorial positions, with the fourth equatorial position being occupied by another carboxy oxygen atom from an adjacent Schiff base; one aqua ligand and one perchlorate oxygen atom ligate at the axial positions, resulting in an elongated octahedral geometry. Each carboxy group in 1 and 2 acts in the syn-anti mode and bridges two adjacent copper(II) atoms via two equatorial positions, resulting in one-dimensional helical (Cu–O–C–O–Cu)n chains. In 3 the copper(II) atom is ligated by two nitrogen atoms, one carboxy oxygen atom from an L3 ligand and another nitrogen atom from pyridine at the equatorial position; the axial positions are occupied by one perchlorato oxygen atom and one carboxy oxygen atom from another L3 ligand, tridentately chelating an adjacent copper(II) atom, resulting in an elongated octahedral geometry. Complex 4 contains a dimeric cation with two very similar square-pyramidally co-ordinated copper(II) atoms. Each L4 ligand chelates a copper(II) atom in a tetradentate mode with the three nitrogen atoms occupying the equatorial positions and the carboxy oxygen atom the apical position. The fourth equatorial position is taken by a carboxy oxygen atom from another L4 ligand chelating another copper(II) atom, resulting in a bis(carboxylato-O)-bridged dimeric structure. The electronic and EPR spectra and redox properties of 1–4 are also discussed.

Synthesis, magnetism, 1H NMR and redox activity of dicopper(II) complexes having a discrete {Cu2(μ-phenoxide)2}2+ unit supported by a non-macrocyclic ligand environment. Crystal structure of [Cu2(L)2(OClO3)2] [HL = 4-methyl-2,6-bis(pyrazol-1-ylmethyl)phenol] †

Reaction between 4-methyl-2,6-bis(pyrazol-1-ylmethyl)phenol (HL) or its 3,5-dimethylpyrazole derivative (HL′) and Cu(ClO4)2·6H2O afforded [CuII2(L/L′)2(OClO3)2] 1 and 2. Complex 1 has been structurally characterized showing that each copper(II) centre is square pyramidal with two bridging phenoxide oxygens and two terminal pyrazole nitrogens in the equatorial plane and a perchlorate oxygen atom axially co-ordinated. Variable-temperature magnetic susceptibility measurements revealed that the dicopper(II) centres are strongly antiferromagnetically coupled [singlet–triplet energy separation, 2J (in cm–1): –1204 for 1 and –798 for 2]. The complexes exhibit 1H NMR spectra within δ 0–10 due to their S = 0 ground state. In MeCN solution they exhibit ligand field transitions in the range 14 300–16 600 cm–1 and phenolate-to-copper(II) charge-transfer transition at ≈22 700 cm–1. In MeCN solution each complex displays three consecutive irreversible responses (scan rate of 50 mV s–1) with Epc values (V vs. SCE) at –0.02, –0.54 and –0.86 (1) and 0.00, –0.42 and –0.80 (2). The first two responses are due to CuII–CuI and the most cathodic response to CuI–Cu0 redox processes, respectively.

Crystal Structure of N,N-Dimethylthioformamide Solvates of the Divalent Group 12 Ions with Linear Coordination Geometry for Mercury(II), Tetrahedral for Zinc(II), and Octahedral for Cadmium(II).

The crystalline solvates of the divalent group 12 metal ions with the soft sulfur donor N,N-dimethylthioformamide display an unusual variation in coordination number and geometry with two, four, and six ligands attached to the mercury(II), zinc(II), and cadmium(II), ions, respectively. Bis(N,N-dimethylthioformamide)mercury(II) perchlorate precipitates from acetonitrile solution when adding less than 2 equiv of N,N-dimethylthioformamide, while the zinc and cadmium solvates crystallize from saturated N,N-dimethylthioformamide solutions. The disolvate [Hg(SCHN(CH(3))(2))(2)](ClO(4))(2) crystallizes in the monoclinic space group P2(1)/n (No. 14) with a = 6.208(1) Å, b = 15.239(7) Å, c = 8.681(2) Å, beta = 99.30(3) degrees, and Z = 2. Centrosymmetric mercury(II) complexes with strong collinear bonds to two N,N-dimethylthioformamide molecules, Hg-S 2.350(2) Å, are joined by double bridges of perchlorate ions in chains along the a-axis by four weak interactions between the mercury and the perchlorate oxygen atoms, mean Hg-O distance 2.84 Å. Tetrakis(N,N-dimethylthioformamide)zinc trifluoromethanesulfonate, [Zn(SCHN(CH(3))(2))(4)](CF(3)SO(3))(2), crystallizes in the triclinic space group P&onemacr; (No. 2) with a = 10.487(3) Å, b = 12.910(3) Å, c = 13.489(5) Å, alpha = 68.800(4) degrees, beta = 69.260(4) degrees, gamma = 74.06(1) degrees, and Z = 2, with the zinc ions tetrahedrally surrounded by four N,N-dimethylthioformamide ligands, mean Zn-S distance 2.34 Å. Also the cadmium solvate of corresponding composition, [Cd(SCHN(CH(3))(2))(4)(CF(3)SO(3))(2)], crystallizes in the space group P&onemacr;, with a = 8.670(1) Å, b = 9.529(1) Å, c = 10.685(1) Å, alpha = 75.20(1) degrees, beta = 66.97(1) degrees, gamma = 65.31(1) degrees, and Z = 1, although the structure comprises centrosymmetric tetrakis(N,N-dimethylthioformamide)bis(trifluoromethanesulfonato)cadmium(II) complexes in which four Cd-S bonds (mean 2.65 Å) and two weaker Cd-O bonds at 2.470(2) Å to the trifluoromethanesulfonate ions give rise to a pseudo-octahedral coordination around the cadmium ion. When using perchlorate instead as counterion, hexakis(N,N-dimethylthioformamide)cadmium perchlorate, [Cd(SCHN(CH(3))(2))(6)](ClO(4))(2), crystallizes in the space group P2(1)/n with a = 12.757(1) Å, b = 7.4681(6) Å, c = 19.732(2) Å, beta = 96.31(1) degrees, and Z = 2. The mean Cd-S bond distance increases to 2.715 Å in the fully solvated cadmium ion with almost regular octahedral coordination geometry to its six centrosymmetrically related ligands. The effect of the weak internal hydrogen bonding occuring between the hydrogen atom of a -CHS group and the sulfur atom of neighboring N,N-dimethylthioformamide ligands is discussed.

Copper monooxygenase models. Aromatic hydroxylation by a dinuclear copper(I) complex containing methionine sulfur ligands

A dinuclear copper(I) complex 1 containing a bis(imine) ligand derived from the condensation between benzene-1,3-dicarbaldehyde and two molecules of L-methionine has been prepared. When this compound reacts with dioxygen a partial aromatic hydroxylation of the ligand occurs, giving a dinuclear µ-phenoxo-µ-hydroxo-dicopper(II) complex 2, together with simple copper oxidation products. Definitive evidence of the monooxygenase activity of the present sulfur-containing model system results from the crystallographic characterisation of the dinuclear copper(II) complex 3 of the hydroxylated dicarbaldehyde, [Cu2{C6H3(CHO)2O}(ClO4)2], which forms upon hydrolysis of the imine groups of 2. In this complex two deprotonated 1,3-diformylphenoxide ligands bind two copper(II) ions, with di-µ-phenoxo bridges. Each copper is essentially square pyramidal, with a basal O4 donor set, including two phenoxide and two carbonyl oxygen atoms from two 2-hydroxybenzene-1,3-dicarbaldehyde ligands. Two perchlorate oxygen atoms are bound in axial positions on opposite sides of the Cu2O6 plane. A minor fraction (15–20%) of 2 contains S-oxygenated methionine residues. However, oxygenation at sulfur is a secondary process, resulting from the reaction of H2O2, formed according to the simple copper(I) oxidation pathway, and the dinuclear copper(II) complex 2.

Inclusion of 4,4'-Bipyridine (γbpy) in Its Copper(II) Aqua Perchlorato Complex. Crystal Structure of [Cu( γbpy )(H2O)2(ClO4)2]n.( γbpy )n

An example of a 4,4'-bipyridine ( γbpy ) clathrate in its copper(II) complex has been established. The compound, [Cu( γbpy )(H2O)2(ClO4)2]n.( γbpy )n, crystallizes in the monoclinic space group C2/c with a 16.651(3), b 11.089(2), c 14.360(3) Ǻ, β 116.45(3)°, V 2373.9(8)Ǻ3. The crystal structure comprises γbpy -bridged linear polymeric [Cu( γbpy )(H2O)2(ClO4)2]n chains, where the copper atom, located on a crystallographic twofold axis, is coordinated in an elongated octahedral environment by two nitrogen atoms of the bridging γbpy ligands (Cu-N 1.998(4)Ǻ) and two water molecules (Cu-O 1.968(3)Ǻ) at the equatorial positions, and two perchlorate oxygen atoms at the axial positions (Cu-O 2.414(4)Ǻ). The chains are interconnected by hydrogen bonds between the aqua ligands and the uncoordinated perchlorate oxygen atoms to form two-dimensional layers with cavities each enclosing a γbpy molecule. Hydrogen bonding between the aqua ligands and the nitrogen atoms of the solvate γbpy molecules further extends the structure into a three-dimensional network in the solid.

Compounds of copper(II) and nickel(II) with 6,6,13,13-tetracarboxy-(andE-6,13-dicarboxy-) substituted 1,4,8,11-tetrazacyclotetradecanes, and carbomethoxy- and carbethoxy- derivatives. Structures of two isomericE-6,13-dicarboxy- (and anE-6,13-dicarbomethoxy-)1,4,8,11-tetrazacyclotetradecane copper(II) perchlorates

Bis(ethanediamine) complex cations of CuII and NiII react with formaldehyde and diethyl- (or dimethyl-) malonate to form complexes of 6,6,13,13-tetracarbomethoxy- (or carbethoxy-) 1,4,8,11-tetraazacyclotetradecane macrocycles. These hydrolyse in base to give tetracarboxy-substituted cations, which decarboxylate in acid toE-6,13-dicarboxy-substituted cations. For CuII, salts of this cation were isolated in a metastable form, which converted in base to the stable form. These isomeric dicarboxy-substituted cations esterified to form perchlorate salts of the isomeric CuII compounds of theE-dicarbomethoxy-substituted cations. The structures of the perchlorate salts of the two isomers of the 6,13-dicarboxy-and the metastable isomer of the 6,13-dicarbomethoxy-substituted macrocycles were determined by x-ray diffraction. All have the macrocycles in squareplanar coordination in theRSSR configuration, with perchlorate oxygen atoms weakly coordinated axially. The metastable dicarboxy- and dicarbomethoxy compounds have the substituent groups axially oriented (1α, 4β, 6β, 8β, 11α, 13α) while the stable dicarboxy-compound has the substituents equatorially oriented (1α, 4β, 6β, 8β, 11α, 13α). The compounds are demetallated very slowly in acid, allowing the isolation of freeE-6,13-dicarboxy-1,4,8,11-tetrazacyclotetradecane.