Synthesis, characterization, and photoresponsive properties of a series of Mo(IV)-Cu(II) complexes

Six Mo(IV)-Cu(II) complexes, [Cu(tpa)](2)[Mo(CN)(8)]·15H(2)O (1, tpa = tris(2-pyridylmethyl)amine), [Cu(tren)](2)[Mo(CN)(8)]·5.25H(2)O (2, tren = tris(2-aminoethyl)amine), [Cu(en)(2)][Cu(0.5)(en)][Cu(0.5)(en)(H(2)O)][Mo(CN)(8)]·4H(2)O (3, en = ethylenediamine), [Cu(bapa)](3)[Mo(CN)(8)](1.5)·12.5H(2)O (4, bapa = bis(3-aminopropyl)amine), [Cu(bapen)](2)[Mo(CN)(8)]·4H(2)O (5, bapen = N,N'-bis(3-aminopropyl)ethylenediamine), and [Cu(pn)(2)][Cu(pn)][Mo(CN)(8)]·3.5H(2)O (6, pn = 1,3-diaminopropane), were synthesized and characterized. Single-crystal X-ray diffraction analyses show that 1-6 have different structures varying from trinuclear clusters (1-2), a one-dimensional belt (3), two-dimensional grids (4-5), to a three-dimensional structure (6). Magnetic and ESR measurements suggest that 1-6 exhibit thermally reversible photoresponsive properties on UV light irradiation through a Mo(IV)-to-Cu(II) charge transfer mechanism. A trinuclear compound [Cu(II)(tpa)](2)[Mo(V)(CN)(8)](ClO(4)) (7) was synthesized as a model of the photoinduced intermediate.     

Hydrido copper clusters supported by dithiocarbamates: oxidative hydride removal and neutron diffraction analysis of [Cu7(H){S2C(aza-15-crown-5)}6

Reactions of Cu(I) salts with Na(S(2)CR) (R = N(n)Pr(2), NEt(2), aza-15-crown-5), and (Bu(4)N)(BH(4)) in an 8:6:1 ratio in CH(3)CN solution at room temperature yield the monocationic hydride-centered octanuclear Cu(I) clusters, [Cu(8)(H){S(2)CR}(6)](PF(6)) (R = N(n)Pr(2), 1(H); NEt(2), 2(H); aza-15-crown-5, 3(H)). Further reactions of [Cu(8)(H){S(2)CR}(6)](PF(6)) with 1 equiv of (Bu(4)N)(BH(4)) produced neutral heptanuclear copper clusters, [Cu(7)(H){S(2)CR}(6)] (R = N(n)Pr(2), 4(H); NEt(2), 5(H); aza-15-crown-5, 6(H)) and clusters 4-6 can also be generated from the reaction of Cu(BF(4))(2), Na(S(2)CR), and (Bu(4)N)(BH(4)) in a 7:6:8 molar ratio in CH(3)CN. Reformation of cationic Cu(I)(8) clusters by adding 1 equiv of Cu(I) salt to the neutral Cu(7) clusters in solution is observed. Intriguingly, the central hydride in [Cu(8)(H){S(2)CN(n)Pr(2)}(6)](PF(6)) can be oxidatively removed as H(2) by Ce(NO(3))(6)(2-) to yield [Cu(II)(S(2)CN(n)Pr(2))(2)] exploiting the redox-tolerant nature of dithiocarbamates. Regeneration of hydride-centered octanuclear copper clusters from the [Cu(II)(S(2)CN(n)Pr(2))(2)] can be achieved by reaction with Cu(I) ions and borohydride. The hydride release and regeneration of Cu(I)(8) was monitored by UV-visible titration experiments. To our knowledge, this is the first time that hydride encapsulated within a copper cluster can be released as H(2) via chemical means. All complexes have been fully characterized by (1)H NMR, FT-IR, UV-vis, and elemental analysis, and molecular structures of 1(H), 2(H), and 6(H) were clearly established by single-crystal X-ray diffraction. Both 1(H) and 2(H) exhibit a tetracapped tetrahedral Cu(8) skeleton, which is inscribed within a S(12) icosahedron constituted by six dialkyl dithiocarbamate ligands in a tetrametallic-tetraconnective (μ(2), μ(2)) bonding mode. The copper framework of 6(H) is a tricapped distorted tetrahedron in which the four-coordinate hydride is demonstrated to occupy the central site by single crystal neutron diffraction. Compounds 1-3 exhibit a yellow emission in both the solid state and in solution under UV irradiation at 77 K, and the structureless emission is assigned as a (3)metal to ligand charge transfer (MLCT) excited state. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations on model compounds match the experimental structures and provide rationalization of their bonding and optical properties.     

Coordination algorithms control molecular architecture: [CuI4(L2)4]4+ grid complex versus [MII2(L2)2X4]y+ side-by-side complexes (M=Mn,Co, Ni,Zn; X=solvent or anion) and [FeII(L2)3][Cl3FeIIIOFeIIICl3

The synthesis and characterisation of a pyridazine-containing two-armed grid ligand L2 (prepared from one equivalent of 3,6-diformylpyridazine and two equivalents of p-anisidine) and the resulting transition metal (Zn, Cu, Ni, Co, Fe, Mn) complexes (1-9) are reported. Single-crystal X-ray structure determinations revealed that the copper(I) complex had self-assembled as a [2 x 2] grid, [Cu(I) (4)(L2)(4)][PF(6)](4).(CH(3)CN)(H(2)O)(CH(3)CH(2)OCH(2)CH(3))(0.25) (2.(CH(3)CN)(H(2)O)(CH(3)CH(2)OCH(2)CH(3))(0.25)), whereas the [Zn(2)(L2)(2)(CH(3)CN)(2)(H(2)O)(2)][ClO(4)](4).CH(3)CN (1.CH(3)CN), [Ni(II) (2)(L2)(2)(CH(3)CN)(4)][BF(4)](4).(CH(3)CH(2)OCH(2)CH(3))(0.25) (5 a.(CH(3)CH(2)OCH(2)CH(3))(0.25)) and [Co(II) (2)(L2)(2)(H(2)O)(2)(CH(3)CN)(2)][ClO(4)](4).(H(2)O)(CH(3)CN)(0.5) (6 a.(H(2)O)(CH(3)CN)(0.5)) complexes adopt a side-by-side architecture; iron(II) forms a monometallic cation binding three L2 ligands, [Fe(II)(L2)(3)][Fe(III)Cl(3)OCl(3)Fe(III)].CH(3)CN (7.CH(3)CN). A more soluble salt of the cation of 7, the diamagnetic complex [Fe(II)(L2)(3)][BF(4)](2).2 H(2)O (8), was prepared, as well as two derivatives of 2, [Cu(I) (2)(L2)(2)(NCS)(2)].H(2)O (3) and [Cu(I) (2)(L2)(NCS)(2)] (4). The manganese complex, [Mn(II) (2)(L2)(2)Cl(4)].3 H(2)O (9), was not structurally characterised, but is proposed to adopt a side-by-side architecture. Variable temperature magnetic susceptibility studies yielded small negative J values for the side-by-side complexes: J=-21.6 cm(-1) and g=2.17 for S=1 dinickel(II) complex [Ni(II) (2)(L2)(2)(H(2)O)(4)][BF(4)](4) (5 b) (fraction monomer 0.02); J=-7.6 cm(-1) and g=2.44 for S= 3/2 dicobalt(II) complex [Co(II) (2)(L2)(2)(H(2)O)(4)][ClO(4)](4) (6 b) (fraction monomer 0.02); J=-3.2 cm(-1) and g=1.95 for S= 5/2 dimanganese(II) complex 9 (fraction monomer 0.02). The double salt, mixed valent iron complex 7.H(2)O gave J=-75 cm(-1) and g=1.81 for the S= 5/2 diiron(III) anion (fraction monomer=0.025). These parameters are lower than normal for Fe(III)OFe(III) species because of fitting of superimposed monomer and dimer susceptibilities arising from trace impurities. The iron(II) centre in 7.H(2)O is low spin and hence diamagnetic, a fact confirmed by the preparation and characterisation of the simple diamagnetic iron(II) complex 8. M?ssbauer measurements at 77 K confirmed that there are two iron sites in 7.H(2)O, a low-spin iron(II) site and a high-spin diiron(III) site. A full electrochemical investigation was undertaken for complexes 1, 2, 5 b, 6 b and 8 and this showed that multiple redox processes are a feature of all of them.     

Structural and electronic differences of copper(I) complexes with tris(pyrazolyl)methane and hydrotris(pyrazolyl)borate ligands

Copper(I) complexes with tripodal nitrogen-containing neutral ligands such as tris(3,5-diisopropyl-1-pyrazolyl)methane (L1') and tris(3-tertiary-butyl-5-isopropyl-1-pyrazolyl)methane (L3'), and with corresponding anionic ligands such as hydrotris(3,5-diisopropyl-1-pyrazolyl)borate (L1-) and hydrotris(3-tertiary-butyl-5-isopropyl-1-pyrazolyl)borate (L3-) were synthesized and structurally characterized. Copper(I) complexes [Cu(L1')Cl] (1), [Cu(L1')(OClO3)] (2), [Cu(L1')(NCMe)](PF6) (3a), [Cu(L1')(NCMe)](ClO4) (3b), [Cu(L1')(CO)](PF6) (4a), and [Cu(L1')(CO)](ClO4) (4b) were prepared using the ligand L1'. Copper(I) complexes [Cu(L3')Cl] (5) and [Cu(L3')(NCMe)](PF6) (6) with the ligand L3' were also synthesized. Copper(I) complexes [Cu(L1)(NCMe)] (7) and [Cu(L1)(CO)] (8) were prepared using the anionic ligand L1-. Finally, copper(I) complexes with anionic ligand L3- and acetonitrile (9) and carbon monoxide (10) were synthesized. The complexes obtained were fully characterized by IR, far-IR, 1H NMR, and 13C NMR spectroscopy. The structures of both ligands, L1' and L3', and of complexes 1, 2, 3a, 3b, 4a, 4b, 5, 6, 7, and 10 were determined by X-ray crystallography. The effects of the differences in (a) the fourth ligand and the counteranion, (b) the steric hindrance at the third position of the pyrazolyl rings, and most importantly, (c) the charge of the N3 type ligands, on the structures, spectroscopic properties, and reactivities of the copper(I) complexes are discussed. The observed differences in the reactivities toward O2 of the copper(I) acetonitrile complexes are traced back to differences in the oxidation potentials determined by cyclic voltammetry. A special focus is set on the carbonyl complexes, where the 13C NMR and vibrational data are presented. Density functional theory (DFT) calculations are used to shed light on the differences in CO bonding in the compounds with neutral and anionic N3 ligands. In correlation with the vibrational and electrochemical data of these complexes, it is demonstrated that the C-O stretching vibration is a sensitive probe for the "electron richness" of copper(I) in these compounds.     

Au(CN)4]- as a supramolecular building block for heterobimetallic coordination polymers

A series of the first coordination polymers using the [Au(CN)(4)](-) anion as a building block has been prepared. The planar tetracyanoaurate anion uses one, two, or four cyano groups to bridge to Ni(II) or Cu(II) centers and exhibits weak Au(III)-N(cyano) interactions between anions. Ni(en)(2)[Au(CN)(4)](2).H(2)O (1, en = ethylenediamine) is a molecular compound with the two [Au(CN)(4)](-) anions coordinating in a trans orientation to Ni(II) without further cyanide coordination. Cu(dien)[Au(CN)(4)](2) (2, dien = diethylenetriamine) forms a similar molecular complex; however, the dimensionality is increased through weak intermolecular Au-N(cyano) interactions of 3.002(14) A to form a 1-D zigzag chain. Cu(en)(2)[Au(CN)(4)](2) (3) also forms a molecular complex similar to 1, but with elongated axial bonds. The complex further aggregates through Au-N(cyano) interactions of 3.035(8) A to form a 2-D array. In [Cu(dmeda)(2)Au(CN)(4)][Au(CN)(4)] (4, dmeda = N,N-dimethylethylenediamine) one [Au(CN)(4)](-) anion coordinates via two cis-N(cyano) donors to the axial sites of two Cu(II) centers to form a 1-D zigzag chain of alternating [Cu(dmeda)(2)](2+) and [Au(CN)(2)](-) units; the other [Au(CN)(4)](-) anion forms a 1-D chain via Au-N(cyano) interactions. In [Cu(bipy)(H(2)O)(2)(Au(CN)(4))(0.5)][Au(CN)(4)](1.5) (5, bipy = 2,2'-bipyridine) one [Au(CN)(4)](-) anion uses all four cyano moieties to bridge four different Cu(II) centers, creating a 1-D chain.     

Endogenous arene hydroxylation promoted by copper(I) cluster helicates

A novel neutral triple-stranded hexanuclear copper(I) cluster helicate [Cu(I)(6)L(3)]·2CH(3)CN derived from a thiosemicarbazone ligand could be synthesized and crystallographically characterized. The MALDI mass spectrum of this complex suggests that the tetranuclear copper(I) cluster helicate [Cu(I)(4)L(2)] is also present in solution. These copper(I) cluster helicates are capable, in the presence of O(2), of hydroxylating the arene linker of their supporting ligand strands. The resulting dinuclear complex [Cu(II)(2)L'(OH)] is formed by two copper(II) centers, a new ligand arising from the hydroxylation reaction, and one hydroxide group. The magnetic investigation of this compound shows a strong antiferromagnetic coupling between the two Cu(II) centers. The kinetic studies for the hydroxylation process show values of ΔH(≠)=-70 kJ mol(-1), similar to those mediated by the tyrosinase enzymes.     

From discrete [Y(DMF)8][Cu4(mu3-I)2(mu-I)3I2] ion pairs to extended [Y(DMF)6(H2O)2][Cu7(mu4-I)3(mu3-I)2(mu-I)4(I)]1infinity and [Y(DMF)6(H2O)3][Cu(I)7Cu(II)2(mu3-I)8(mu-I)6]2infinity arrays by H-bond templating in a confined solvent-free environment

An ionic heterometallic species [Y(DMF)(8)][Cu(4)(micro(3)-I)(2)(micro-I)(3)I(2)](1) was isolated from a solution of CuI, NH(4)I and YI(3)(Pr(i)OH)(4) in DMF-isopropoxyethanol, and was converted in a confined environment by progressive substitution of the DMF ligands with water molecules first into a 1D zig-zag structure [Y(DMF)(6)(H(2)O)(2)][Cu(7)(micro(4)-I)(3)(micro(3)-I)(2)(micro-I)(4)(I)](1infinity)(2) and finally into a 2D sheet [Y(DMF)(6)(H(2)O)(3)][Cu(I)(7)Cu(II)(2)(micro(3)-I)(8)(micro-I)(6)](2infinity)(3) by H-bond templating.     

Mononuclear and binuclear copper(I) complexes ligated by bis(3,5-diisopropyl-1-pyrazolyl)methane: insight into the fundamental coordination chemistry of three-coordinate copper(I) complexes with a neutral coligand

By using the neutral bidentate nitrogen-containing ligand, bis(3,5-diisopropyl-1-pyrazolyl)methane (L1' '), the copper(I) complexes [Cu(L1' ')2](CuCl2) (1CuCl2), [Cu(L1' ')2](ClO4) (1ClO4), [Cu(L1' ')]2(ClO4)2 (2ClO4), [Cu(L1' ')]2(BF4)2 (2BF4), [Cu(L1' ')(NCMe)](PF6) (3PF6), [Cu(L1' ')(PPh3)](ClO4) (4ClO4), [Cu(L1' ')(PPh3)](PF6) (4PF6), [{Cu(L1' ')(CO)}2(mu-ClO4)](ClO4) (5ClO4), and the copper(II) complexes [{Cu(L1' ')}2(mu-OH)2(mu-ClO4)2] (6), and [Cu(L1' ')Cl2] (7) were systematically synthesized and fully characterized by X-ray crystallography and by IR and 1H NMR spectroscopy. In the case of copper(II), ESR spectroscopy was also applied. In comparison with the related neutral tridentate ligand L1', bis-chelated copper(I) complexes and binuclear linear-coordinated copper(I) complexes are easy to obtain with L1' ', like 1CuCl2, 1ClO4, 2ClO4, and 2BF4. Importantly, stronger and bulkier ligands such as acetonitrile (3PF6) and especially triphenylphosphine (4ClO4 and 4PF6) generate three-coordinate structures with a trigonal-planar geometry. Surprisingly, for the smaller ligand carbon monoxide, a mononuclear three-coordinate structure is very unstable, leading to the formation of a binuclear complex (5ClO4) with one bridging perchlorate anion, such that the copper(I) centers are four-coordinate. The same tendency is observed for the copper(II) bis(mu-hydroxo) compounds 6, which is additionally bridged by two perchlorate anions. Both copper(II) complexes 6 and 7 were obtained by molecular O2 oxidation of the corresponding copper(I) complexes. A comparison of the new copper(I) triphenylphosphine complexes 4ClO4 and 4PF6 with corresponding species obtained with the related tridentate ligands L1' and L1 (8ClO4 and 9, respectively) reveals surprisingly small differences in their spectroscopic properties. Density functional theory (DFT) calculations are used to shed light on the differences in bonding in these compounds and the spectral assignments. Finally, the reactivity of the different bis(pyrazolyl)methane complexes obtained here toward PPh3, CO, and O2 is discussed.     

Heterobimetallic coordination polymers incorporating [M(CN)(2)](-) (M = Cu,Ag) and [Ag(2)(CN)(3)](-) units: increasing structural dimensionality via M-M' and M...NC interactions

A series of new heterometallic coordination polymers has been prepared from the reaction of metal-ligand cations and KAg(CN)(2) units. Many of these contain silver-silver (argentophilic) interactions, analogous to gold-gold interactions, which serve to increase supramolecular structural dimensionality. Compared to [Au(CN)(2)](-) analogues, these polymers display new trends specific to [Ag(CN)(2)](-), including the formation of [Ag(2)(CN)(3)](-) and the presence of Ag...N interactions. [Cu(en)(2)][Ag(2)(CN)(3)][Ag(CN)(2)] (1, en = ethylenediamine) forms 1-D chains of alternating [Ag(CN)(2)](-) and [Ag(2)(CN)(3)](-) units via argentophilic interactions of 3.102(1) A. These chains are connected into a 2-D array by strong cyano(N)-Ag interactions of 2.572(3) A. [Cu(dien)Ag(CN)(2)](2)[Ag(2)(CN)(3)][Ag(CN)(2)] (2, dien = diethylenetriamine) forms a 1-D chain of alternating [Cu(dien)](2+) and [Ag(CN)(2)](-) ions with the Cu(II) atoms connected in an apical/equatorial fashion. These chains are cross-linked by [Ag(2)(CN)(3)](-) units via argentophilic interactions of 3.1718(8) A and held weakly in a 3-D array by argentophilic interactions of 3.2889(5) A between the [Ag(CN)(2)](-) in the 2-D array and the remaining free [Ag(CN)(2)](-). [Ni(en)][Ni(CN)(4)].2.5H(2)O (4) was identified as a byproduct in the reaction to prepare the previously reported [Ni(en)(2)Ag(2)(CN)(3)][Ag(CN)(2)] (3). In [Ni(tren)Ag(CN)(2)][Ag(CN)(2)] (5, tren = tris(2-aminoethyl)amine), [Ni(tren)](2+) cations are linked in a cis fashion by [Ag(CN)(2)](-) anions to form a 1-D chain similar to the [Au(CN)(2)](-) analogue. [Cu(en)Cu(CN)(2)Ag(CN)(2)] (6) is a trimetallic polymer consisting of interpenetrating (6,3) nets stabilized by d(10)-d(10) interactions between Cu(I)-Ag(I) (3.1000(4) A). Weak antiferromagnetic coupling has been observed in 2, and a slightly stronger exchange has been observed in 6. The Ni(II) complexes, 4 and 5, display weak antiferromagnetic interactions as indicated by their relatively larger D values compared to that of 3. Magnetic measurements on isostructural [Ni(tren)M(CN)(2)][M(CN)(2)] (M = Ag, Au) show that Ag(I) is a more efficient mediator of magnetic exchange as compared to Au(I). The formation of [Ni(CN)(4)](2)(-), [Ag(2)(CN)(3)](-), and [Cu(CN)(2)](-) are all attributed to secondary reactions of the dissociation products of the labile KAg(CN)(2).     

Electronic and structural variation among copper(II) complexes with substituted phenanthrolines

A series of copper(II) complexes with substituted phenanthroline ligands has been synthesized and characterized electronically and structurally. The compounds that have been prepared include the monosubstituted ligand complexes of the general formula [Cu(5-R-phen)(2)(CH(3)CN)](BF(4))(2), where R = NO(2), Cl, H, or Me, and the disubstituted ligand complex [Cu(5,6-Me(2)-phen)(2)(CH(3)CN)](BF(4))(2). The complexes [Cu(5-NO(2)-phen)(2)(CH(3)CN](BF(4))(2) (1), [Cu(5-Cl-phen)(2)(CH(3)CN)](BF(4))(2) (2), [Cu(o-phen)(2)(CH(3)CN)](BF(4))(2) (3), and [Cu(5-Me-phen)(2)(CH(3)CN)](BF(4))(2) (4) each crystallize in the space group C2/c with compounds 1, 2, and 4 comprising an isomorphous set. The disubstituted complex [Cu(5,6-Me(2)-phen)(2)(CH(3)CN)](BF(4))(2) (5) crystallizes in the space group P2(1)/c. Each structure is characterized by a distorted trigonal bipyramidal arrangement of ligands around the central copper atom with approximate or exact C(2) symmetry. The progression from electron-withdrawing to electron-donating substituents on the phenanthroline ligands correlates with less accessible reduction potentials for the bis-chelate complexes.     

Reporting a unique example of electronic bistability observed in the form of valence tautomerism with a copper(II) helicate of a redox-active nitrogenous heterocyclic ligand

Valence tautomeric compounds involving nondixolene-type ligands are rare. The triple-helicate copper(II) complex [Cu(II)(2)(L)(3)](ClO(4))(4)·3CH(3)CN (1) containing a redox-active N-heterocyclic ligand (L) has been prepared and displays VT equilibrium in solution, as established by electronic spectroscopy, electron paramagnetic resonance spectroscopy, and cyclic and differential pulse voltammetry carried out at variable temperatures. The process involves intramolecular transfer of an electron from one of the L ligands to a copper(II) center, leading to the oxidation of L to an L(?+) radical with concomitant reduction of the Cu(II) center to Cu(I), as shown by the equilibrium [Cu(II)Cu(I)L(?+)L(2)](4+) ? [Cu(II)(2)L(3)](4+).     

Synthesis and characterization of di- and trivalent pyrazolylborate β-diketonates and cyanometalates

The syntheses, structures, and magnetic properties of a series of di- and trivalent hydridotris(3,5-dimethylpyrazol-1-yl)borate (Tp*) cyanomanganates are described. Treatment of tris(acetylacetonate)manganese(III) [Mn(acac)(3)] with KTp* and tetra(ethyl)ammonium cyanide affords [NEt(4)][(Tp*)Mn(II)(κ(2)-acac)(CN)] (1), as the first monocyanomanganate(II) complex; attempted oxidation of 1 with iodine affords {(Tp*)Mn(II)(κ(2)-acac(3-CN))}(n) (2) as a one-dimensional chain and bimetallic {[NEt(4)][(Tp*)Mn(II)(κ(2)-acac(3-CN))](2)(μ-CN) (3) as the major and minor products, respectively. A fourth complex, [NEt(4)][(Tp*)Mn(II)(η(2)-acac(3-CN))(η(1)-NC-acac)] (4), is obtained via treatment of Mn(acac(3-CN))(3) with KTp* and [NEt(4)]CN, while [NEt(4)](2)[Mn(II)(CN)(4)] (5) was prepared from manganese(II) trifluoromethanesulfonate and excess [NEt(4)]CN. Tricyanomanganate(III) complexes, [cat][(Tp*)Mn(III)(CN)(3)] [cat = NEt(4)(+), 7; PPN(+), 8], are prepared via sequential treatment of Mn(acac(3-CN))(3) with KTp*, followed by [NEt(4)]CN, or [cat](3)[Mn(III)(CN)(6)] with (Tp*)SnBu(2)Cl. Magnetic measurements indicate that 1, 2, and 4 contain isotropic Mn(II) (S = (5)/(2); g = 2.00) centers, and no long-range magnetic ordering is found above 1.8 K. Compounds 7 and 8 contain S = 1 Mn(III) centers that adopt singly degenerate spin ground states without orbital contributions to their magnetic moments.     

Compositions and structures of copper hexacyanoferrates(II) and (III): experimental results

The preparation, composition and structure of copper hexacyanoferrates have been investigated. Three methods were used: precipitation, local growth in an aqueous solution, and growth in a gel. Four compounds were obtained, either in powdered form or as single crystals: Cu(II)(2)Fe(II)(CN)(6) . xH(2)O, Cu(II)(3)[Fe(III)(CN)(6)](2) . xH(2)O, Na(2)Cu(II)Fe(II)(CN)(6) . 10H(2)O and K(2)Cu(II)Fe(II)(CN)(6). Powders of Cu(II)(2)Fe(II)(CN)(6) . xH(2)O and Cu(II)(3)[Fe(III) (CN)(6)](2) . xH(2)O are easily prepared by precipitation and can also be obtained by local growth. They crystallise generally with cubic symmetry, in space group Fm3m, and are structurally disordered. The mixed copper hexacyanoferrates of general formulae M(1)(2)Cu(II)Fe(II)(CN)(6) or M(I)Cu(II)Fe(III)(CN)(6) (here M(I) is Na, K) were not obtained by precipitation. The appropriate method was local growth for the preparation of powders of K(2)Cu(II)Fe(II)(CN)(6). Single crystals of Na(2)Cu(II)Fe(II)(CN)(6) were obtained by growth in a gel, and their study using single crystal X-ray diffraction revealed a new monoclinic structure.     

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.     

Structure and magnetic ordering of the anomalous layered (2D) ferrimagnet [NEt4]2Mn(II)3(CN)8 and 3D bridged-layered antiferromagnet [NEt4]Mn(II)3(CN)7 Prussian blue analogues

The reaction of Mn(II) and [NEt(4)]CN leads to the isolation of solvated [NEt(4)]Mn(3)(CN)(7) (1) and [NEt(4)](2) Mn(3)(CN)(8) (2), which have hexagonal unit cells [1: R3m, a = 8.0738(1), c = 29.086(1)??; 2: P3m1, a = 7.9992(3), c = 14.014(1)??] rather than the face centered cubic lattice that is typical of Prussian blue structured materials. The formula units of both 1 and 2 are composed of one low- and two high-spin Mn(II) ions. Each low-spin, octahedral [Mn(II)(CN)(6)](4-) bonds to six high-spin tetrahedral Mn(II) ions through the N?atoms, and each of the tetrahedral Mn(II) ions are bound to three low-spin octahedral [Mn(II)(CN)(6)](4-) moieties. For 2, the fourth cyanide on the tetrahedral Mn(II) site is C?bound and is terminal. In contrast, it is orientationally disordered and bridges two tetrahedral Mn(II) centers for 1 forming an extended 3D network structure. The layers of octahedra are separated by 14.01?? (c?axis) for 2, and 9.70?? (c/3) for 1. The [NEt(4)](+) cations and solvent are disordered and reside between the layers. Both 1 and 2 possess antiferromagnetic superexchange coupling between each low-spin (S = 1/2) octahedral Mn(II) site and two high-spin (S = 5/2) tetrahedral Mn(II) sites within a layer. Analogue 2 orders as a ferrimagnet at 27(±1)?K with a coercive field and remanent magnetization of 1140?Oe and 22,800?emuOe?mol(-1), respectively, and the magnetization approaches saturation of 49,800?emuOe?mol(-1) at 90,000?Oe. In contrast, the bonding via bridging cyanides between the ferrimagnetic layers leads to antiferromagnetic coupling, and 3D structured 1 has a different magnetic behavior to 2. Thus, 1 is a Prussian blue analogue with an antiferromagnetic ground state [T(c) = 27?K from d(χT)/dT].     

Modeling Tyrosinase Monooxygenase Activity. Spectroscopic and Magnetic Investigations of Products Due to Reactions between Copper(I) Complexes of Xylyl-Based Dinucleating Ligands and Dioxygen: Aromatic Ring Hydroxylation and Irreversible Oxidation Products

A full account of a chemical system possessing features that mimic the reactivity aspects of tyrosinase is presented. Using dinucleating ligands with a m-xylyl spacer three new dicopper(I) complexes have been synthesized and their reactivity with dioxygen investigated. The six-membered chelate ring forming ligands provide only two nitrogen coordinations to each copper. The complexes [Cu(I)(2)L(CH(3)CN)(2)]X(2) (X = ClO(4)(-) (1a), SbF(6)(-) (1b)) and [Cu(I)(2)(L-NO(2))(CH(3)CN)(2)][SbF(6)](2) (1c) [L = alpha,alpha'-bis[N-methyl-N-(2-pyridylethyl)amino]-m-xylene; L-NO(2) = para-nitro derivative of L] have been characterized by IR and (1)H NMR spectroscopy. The reaction of O(2) with 1a-c in CH(2)Cl(2) or THF is instantaneous and causes stoichiometric xylyl hydroxylation reactions producing phenol products. Thus 1a produces phenoxo-/hydroxo-bridged product [Cu(II)(2)(L-O)(OH)][ClO(4)](2) (2a). The existence of putative peroxo-dicopper(II) species could not be detected even at -80 degrees C. A trend is observed for the extent of aromatic ring hydroxylation (298 K): CH(3)CN approximately DMF > CH(3)OH > CH(2)Cl(2). Cyclic voltammetric experiment of 1a in DMF reveals an appreciably low redox potential (E(1/2) = -0.26 V vs SCE) for the Cu(II)(2)/Cu(I)(2) redox process. Variable-temperature (25-300 K) magnetic susceptibility measurements establish that the copper(II) centers in 2a and the dihydroxo-bridged complex [Cu(II)(2)L'(OH)(2)][ClO(4)](2) (2b) [formed due to an impurity (L') present during the synthesis of L following Method A; L' = bis[alpha,alpha'-bis(N-methyl-N-(2-pyridylethyl)amino)-m-xylene]methylamine] are antiferromagnetically coupled, with 2a considerably more coupled than 2b. Reaction of 1a with O(2) in CH(2)Cl(2) (298 K) produces an additional unhydroxylated product of composition [Cu(II)(2)L(OH)(OH(2))][ClO(4)](3).2H(2)O.0.5HCl (3a). In agreement with its proposed hydroxo-/aquo-bridged structure, 3a is weakly antiferromagnetically coupled. In CH(3)CN solution, 3a rearranges to generate a doubly hydroxo-bridged species [Cu(II)(2)L(OH)(2)](2+). Using a solution-generated dicopper(I) complex of a closely similar ligand (L' ') providing five-membered chelate ring, the reactivity toward dioxygen was also investigated. It produces only an irreversibly oxidized product of composition Cu(II)(2)L' '(OH)(ClO(4))(3)(H(2)O)(2) (3b) (L' ' = alpha,alpha'-bis[N-methyl-N-(2-pyridylmethyl)amino]-m-xylene). For 3b the copper(II) centers are almost uncoupled.     

Hybrid inorganic-metalorganic compounds containing copper(II)-monosubstituted Keggin polyanions and polymeric copper(I) complexes

Four hybrid inorganic-metalorganic compounds containing copper(II)-monosubstituted Keggin polyoxotungstates, K3[Cu(I)(4,4'-bpy)]3[SiW11Cu(II)O39].11H2O (1), (paraquat)3[SiW11Cu(II)O39].6H2O (2; paraquat = N,N'-dimethyl-4,4'-bipyridinium), K3[Cu(I)(4,4'-bpy)]3[GeW11Cu(II)O39].11H2O (3), and Na2[Cu(I)(4,4'-bpy)]3[PW11Cu(II)O39(H2O)].4H2O (4), have been synthesized under autogenous pressure hydrothermal conditions and characterized by elemental analysis and infrared spectroscopy (FT-IR). The crystal structures of 1, 2, and 4 have been established by single-crystal X-ray diffraction. The crystal packings are characterized by the presence of monodimensional extended entities: either the polymeric polyanion [SiW11CuO39]n(6n-) (2), the cationic [Cu(4,4'-bpy)]n(n+) chain (4), or both simultaneously as in compound 1, where the inorganic and metalorganic sublattices are mutually perpendicular. To asses the influence of packing in the copper(I) complex structural diversity found in compounds 1 and 4, a search in the CSD database has been performed and the resulting geometrical features have been analyzed and compared with experimental crystallographic data and DFT calculations.     

A novel three-dimensional network constructed from tetramolybdate clusters linked via two types of copper complex fragments: synthesis, characterization, and magnetic behavior of [[CuII(2,2'-bpy)][CuII(IN)2][Mo4O12(OH)2]

A novel three-dimensional copper molybdate with mixed ligands, [[Cu(II)(2,2'-bpy)][Cu(II)(IN)(2)][Mo(4)O(12)(OH)(2)]] (IN(-) = isonicotinate ion, 2,2'-bpy = 2,2'-bipyridine), 1, has been hydrothermally synthesized and structurally characterized, and this compound is built from an unprecedented tetranuclear molybdenum oxide cluster covalently bonded to two types of copper complex fragments, [Cu(II)(2,2'-bpy)](2+) and [Cu(II)(IN)(2)], via terminal oxygen atoms of [MoO(6)] octahedra. Crystal data for compound 1: monoclinic, space group C2/c, a = 16.4755 A, b = 10.3714 A, c = 17.4382 A, alpha = 90.0000 degrees, beta = 94.8098 degrees, gamma = 90.0000 degrees; V = 2969.24 A(3); Z = 2. Variable temperature magnetic susceptibility indicates that both ferromagnetic and antiferromagnetic interactions exist in 1.     

Cuprophilic interactions in luminescent copper(I) clusters with bridging bis(dicyclohexylphosphino)methane and iodide ligands: spectroscopic and structural investigations

Polynuclear copper(I) complexes with bridging bis(dicyclohexylphosphino)methane (dcpm) and iodide ligands, [Cu(2)(dcpm)(2)(CH(3)CN)(2)](BF(4))(2) (1), [Cu(2)(dcpm)(2)](BF(4))(2) (2), [(CuI)(3)(dcpm)(2)] (3), [(CuI)(4)(dcpm)(2)] (4), and [(CuI)(2)(dcpm)(2)] (5) were prepared and their structures determined by X-ray crystal analysis. The shortest Cu--Cu distance found in these complexes is 2.475(1) A for 3. Powdered samples of 1, 3, 4, and 5 display intense and long-lived phosphorescence with lambda(max) at 460, 626, 590, and 456 nm and emission quantum yields of 0.26, 0.11, 0.12, and 0.56 at room temperature, respectively. In the solid state, 2 displays both a weak emission at 377 and an intense one at 474 nm with an overall emission yield 0.42. The difference in emission properties among complexes 1-5 suggests that both Cu--Cu interaction and coordination around the copper(I) center affect the excited state properties. A degassed solution of 2 in acetone gives a bright red emission with lambda(max) at 625 nm at room temperature. The difference absorption spectra of the triplet excited states of 1-5 in acetonitrile show broad absorption peaks at 340-410 and 850-870 nm.     

Ferromagnetic interaction in mu1,3-cyanamido-derived copper(II) cryptates

The reaction of dinuclear copper(II) cryptates with calcium cyanamide, CaNCN, and sodium dicyanamide, Na[N(CN)(2)] results in dinuclear compounds of formulae [Cu(2)(HNCN)(R3Bm)](ClO(4))(3) (1), [Cu(2)(dca)(R3Bm)](ClO(4))(3)4H(2)O (2), and [Cu(2)(NCNCONH(2))(R3Bm)](CF(3)SO(3))(3) (3), in which R3Bm=N[(CH(2))(2)NHCH(2)(C(6)H(4)-m)CH(2)NH(CH(2))(2)](3)N and dca=dicyanamido ligand (NCNCN(-)). The X-ray diffraction analysis reveals for both 1 and 3 a dinuclear entity in which the copper atoms are bridged by means of the -NCN- unit. The molar magnetic susceptibility measurements of 1-3 in the 2-300 K range indicate ferromagnetic coupling. The calculated J values, by using theoretical methods based on density functional theory (DFT) are in excellent agreement with the experimental data. Catalytic hydration of a nitrile to an amide functional group is assumed responsible for the formation of 3 from a mu(1,3)-dicyanamido ligand.