juan cano

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Papers by juan cano

Significant antiferromagnetic coupling in a terephthalate (ta)-bridged manganese(II) compound: preparation, crystal structure and magnetic properties of the chain [Mn2(bipy)4(ta)][ClO4]2(bipy = 2,2?-bipyridine)

Journal of The Chemical Society-dalton Transactions, 1994

... 2, RE Coffman and GR Buettner, J. Phys. Chem., 1979, 83, 2387 Article ChemPort . 3, TR Feltho... more

Synthesis, spectroscopic characterization and electrochemical behaviour of nickel(II) complexes with C-meso-5,5,7,12,12,14-hexamethylcyclotetradecane (Me6[14]aneN4). Crystal structure of {Ni(Me6[14]aneN4)|I2

Transition Metal Chemistry, 1993

Magneto-Structural Effects of the Jahn-Teller Distortions on 2,2'-Bipyrimidine-, (bpm-) Bridged Dinuclear Copper(II) Complexes: Crystal Structures and Magnetic Properties of [Cu2(bpm)(H2O)4(SO4)2].cntdot.3H2O and [Cu2(bpm)(H2O)8](SO4)2.cntdot.2H2O

Inorganic Chemistry, 1995

(2) (bpm = 2,2'-bipyrimidine) have been synthesized and structurally characterized by X-ray diffr... more (2) (bpm = 2,2'-bipyrimidine) have been synthesized and structurally characterized by X-ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P21ln, with a = 7.651(1) A, b = 25.119(3) A, c = 11.050(1) A, , L? = 108.80(1)", Z = 4 and V = 2010.4(4) A3, whereas compound 2 is orthorhombic, space group Pbcn, with a = 13.401(2) A, b = 12.116(2) A, c = 14.178(4) A, Z = 4, and V = 2302.0(6) A3. The structure of 1 consists of a 2D-array of copper(I1) ions bridged by bis-bidentate bpm groups and bis-unidentate sulfate. Each copper atom in 1 is in an elongated octahedral CuO6 surrounded by two water molecules and two nitrogen atoms from bpm building the basal plane and two sulfate oxygens in the axial positions. The structure of 2 is made up of noncentrosymmetric dinuclear [Cuz(bpm)(H20)8I4+ cationic units, uncoordinated sulfate anions, and water of crystallization. Both copper(I1) ions in 2 have distorted octahedral CuO6 surroundings, one being compressed and the other elongated. Compounds 1 and 2 exhibit antiferromagnetic coupling, which is relatively strong in the former (J(sing1et-triplet energy gap) = -159 cm-') and weak in the latter (J = -24 cm-I). The influence of the distortions (elongation or compression) of the copper environment on the exchange coupling in 1 and 2 is analyzed by extended Hiickel calculations in the framework of a simple orbital model. Yao, X. K.; Wang, H. G.; Wang, G. L. Inorg. Chim. Acta 1990, 173, 201. (h) Ribas, J.; Diaz, C.; Costa, R.; Journaux, Y.; MathoniBre, C.; Kahn, 0.; Gleizes, A. Inorg. Chem. 1990, 29, 2042. (i) Fabretti, A. C.; Giusti, A.; Albano, V. G.; Castellari, C.; Gatteschi, D.; Sessoli, R. J. Chem. Soc., Dalton Trans. 1991,2133. (i) Ribas, J.; Garcia, A.; Costa, R.; Monfort, M.; Alvarez, S.; Zanchini, C.; Solans, X.; Domenech, M. V. Inorg. Chem. 1991, 30, 841. (k) Escuer, A.; Vicente, R.; Ribas, J.; Costa, R.; Solans, X . Inorg. Chem. 1992, 31, 2627. (1) Benelli, C.; Fabretti, A. C.; Giusti, A. J. Chem. Soc., Dalton Trans. 1993, 409. (m) Costa, R.; Garcia, A,; Ribas, J.; Mallah, T.; Joumaux, Y.; Sletten, J.; Solans, X.; Rodriguez, V. Inorg. Chem. 1993, 32, 3733. (n) Real, J. A.; Mollar, M.; Ruiz, R.; Faus, J.; Lloret, F.; Julve, M.; Philoche-Levisdes, M. Okawa, H.; Sakiyama, H.; Ohba, M.; Matsumoto, N.; Kurisaki, T.; Wakita, H. J . Chem. SOC., Dalton Trans. 1993, 2991.

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[Cr(phen)(ox)2]-: a versatile bis-oxalato building block for the design of heteropolymetallic systems. Crystal structures and magnetic properties of AsPh4[Cr(phen)(ox)2]·H2O, [NaCr(phen)(ox)2(H2O)]·2H2O and {[Cr(phen)(ox)2]2[Mn2(bpy)2(H2O)2(ox)]}·6H2O

New Journal of Chemistry, 2000

... and {[Cr(phen)(ox) 2 ] 2 [Mn 2 (bpy) 2 (H 2 O) 2 (ox)]}·6H 2 O. Gabriela Marinescu, Marius An... more

Nuclearity Controlled Cyanide-Bridged Bimetallic CrIII-MnII Compounds: Synthesis, Crystal Structures, Magnetic Properties and Theoretical Calculations

Chemistry-a European Journal, 2004

The preparation, X-ray crystallography and magnetic investigation of the compounds PPh4[Cr(bipy)(... more The preparation, X-ray crystallography and magnetic investigation of the compounds PPh4[Cr(bipy)(CN)4]⋅2 CH3CN⋅H2O (1) (mononuclear), [{Cr(bipy)(CN)4}2Mn(H2O)4]⋅4 H2O (2) (trinuclear), [{Cr(bipy)(CN)4}2Mn(H2O)2] (3) (chain) and [{Cr(bipy)(CN)4}2Mn(H2O)]⋅H2O⋅ CH3CN (4) (double chain) [bipy=2,2′-bipyridine; PPh4+=tetraphenylphosphonium] are described herein. The [Cr(bipy)(CN)4]− unit act either as a monodentate (2) or bis-monodentate (3) ligand toward the manganese atom through one (2) or two (3) of its four cyanide groups. The manganese atom is six-coordinate with two (2) or four (3) cyanide nitrogens and four (2) or two (3) water molecules building a distorted octahedral environment. In 4, two chains of 3 are pillared through interchain Mn-N-C-Cr links which replace one of the two trans-coordinated water molecules at the manganese atom to afford a double chain structure where bis- and tris-monodenate coordination modes of [Cr(bipy)(CN)4]− coexist. The magnetic properties of 1–4 were investigated in the temperature range 1.9–300 K. A Curie law behaviour for a magnetically isolated spin quartet is observed for 1. A significant antiferromagnetic interaction between CrIII and MnII through the single cyanide bridge [J=−6.2 cm−1, the Hamiltonian being defined as Ĥ=−J(ŜCr(1)⋅ŜMn+ŜCr(2)⋅ŜMn)] occurs in 2 leading to a low-lying spin doublet which is fully populated at T <5 K. A metamagnetic behaviour is observed for 3 and 4 [the values of the critical field Hc being ca. 3000 (3) and 1500 Oe (4)] which is associated to the occurrence of weak interchain antiferromagnetic interactions between ferrimagnetic MnII chains. The analysis of the exchange pathways in 2–4 through DFT type calculations together with the magnetic bevaviour simulation using the quantum Monte Carlo methodology provided a good understanding of their magnetic properties.

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Magnetic Coupling through the Carbon Skeleton of Malonate in Two Polymorphs of {[Cu(bpy)(H 2 O)][Cu(bpy)(mal)(H 2 O)]}(ClO 4 ) 2 (H 2 mal = Malonic Acid; bpy = 2,2‘Bipyridine)

Inorganic Chemistry, 2000

Two polymorphic malonato-bridged copper(II) complexes of formula ([Cu(bpy)(H2O)][Cu(bpy)(mal)(H2O... more Two polymorphic malonato-bridged copper(II) complexes of formula ([Cu(bpy)(H2O)][Cu(bpy)(mal)(H2O)])-(ClO4)2 (1 and 2) (bpy = 2,2&amp;amp;amp;amp;#39;-bipyridine and mal = malonate dianion) have been prepared and their structures solved by X-ray diffraction methods. Compound 1 crystallizes in the monoclinic space group P2(1)/a, with a = 23.743(3) A, b = 9.7522(5) A, c = 27.731(2) A, beta = 114.580(10) degrees, and Z = 4. Compound 2 crystallizes in the orthorhombic space group Pbcn, with a = 23.700(5) A, b = 25.162(5) A, c = 9.693(5) A, and Z = 4. The structures of 1 and 2 are made up of uncoordinated perchlorate anions and malonate-bridged zigzag copper(II) chains grouped in an isosceles triangle running parallel to the b (1) and c (2) axes. These chains are built by a [Cu(bpy)(mal)(H2O)] unit acting as bis-monodentate ligand toward two [Cu(bpy)(H2O)] adjacent units through its OCCCO skeleton in an anti-anti conformation, whereas the OCO carboxylate bridges exhibit the anti-syn conformation. Compounds 1 and 2 contain four crystallographically independent copper(II) atoms, but the environment of all of them is distorted square pyramidal: the axial position is occupied by a water molecule, whereas the equatorial plane is formed by a chelating bpy and either a bidentate malonate or two carboxylate oxygens from two malonate groups. The equatorial Cu-O(mal) (1.911(4)-1.978(4) (1) and 1.897(5)-1.991(4) A (2)) and Cu-N(bpy) (1.983(4)-2.008(5) (1) and 1.971(6)-2.007(6) A (2)) bonds are somewhat shorter than the axial Cu-O(w) one (2.257(5)-2.524(5) (1) and 2.236(5)-2.505(6) A (2)). The angles subtended at the copper atom by the chelating bpy vary in the ranges 80.9(2)-81.8(2) degrees (1) and 80.4(2)-82.1(2) degrees (2), values which are somewhat smaller than those of the chelating malonate (80.4(2)-82.1(2) degrees (1) and 93.0(2)-93.6(2) degrees (2)). The intrachain copper-copper separations through the OCCCO fragment are 8.227(1) (1) and 8.206(2) A (2), whereas those through the OCO bridging unit are 4.579(1)-5.043(1) (1) and 4.572(2)-5.040(2) A (2). The magnetic behavior of 1 and 2 in the temperature range 2.0-290 K is very close, and it corresponds to an overall ferromagnetic coupling, the chi MT versus T curve exhibiting a maximum at 18 K. The analysis of the magnetic data through a numerical expression derived for the real topology of 1 and 2, that is, chains of isosceles triangles with two intrachain exchange pathways J1 (exchange coupling through the OCO carboxylate) and J2 (exchange coupling through the OCCCO malonate), indicates the occurrence of ferro- (J1 = +4.6 cm-1) and antiferromagnetic couplings (J2 = -4.2 cm-1). The magnetic coupling through these exchange pathways is further analyzed and substantiated by density functional theory calculations on a malonate-bridged trinuclear copper(II) model system.

Ability of terephthalate (ta) to mediate exchange coupling in ta-bridged copper(II), nickel(II), cobalt(II) and manganese(II) dinuclear complexes

Journal of The Chemical Society-dalton Transactions, 1997

J. Chem. Soc., Dalton Trans., 1997, Pages 19151923 ... Ability of terephthalate (ta) to mediate ... more

Topology and Spin Polarization in Sheetlike Metal(II) Polymers: [ML 2 X 2 ] (M ˭ Mn, Fe, Co or Ni, L = Pyrimidine or Pyrazine and X = NCS or NCO)

Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1999

CrossRef is an independent membership association, founded and directed by publishers. CrossRef&#... more CrossRef is an independent membership association, founded and directed by publishers. CrossRef's mandate is to connect users to primary research content, by enabling publishers to do collectively what they can't do individually. CrossRef is also the official DOI registration agency for ...

An Azide-Bridged Copper(II) Ferromagnetic Chain Compound Exhibiting Metamagnetic Behavior

Inorganic Chemistry, 1997

The one-dimensional chain complex [Cu(2)(&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp... more The one-dimensional chain complex [Cu(2)(&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;mgr;(2)-1,1-N(3))(2)(&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;mgr;(2)-1,3-NO(3))(2)(&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;mgr;(2)-1,3-Me(3)NCH(2)CO(2))(2)](n)() (1) contains three different bridge groups, &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;mgr;(2)-1,1-azide (end-on), &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;mgr;(2)-nitrate, and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;mgr;(2)-syn,syn-carboxylate, arranged so that the azide and carboxylate groups bridge equatorially and dictate the intrachain magnetic behavior between the copper magnetic orbitals. Variable-temperature magnetic susceptibility studies at low field, and magnetization studies at variable field, reveal dominant intrachain ferromagnetism (J = 26 cm(-)(1)) but also much weaker interchain ferromagnetism (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;THETAV; = 2.3 K) and antiferromagnetism (J(eff) = -0.18 cm(-)(1)). The structure has been rationalized in terms of a layered magnetic model with antiferromagnetic coupling between ferromagnetically coupled layers, leading to metamagnetic behavior. The intrachain ferromagnetism is explained satisfactorily using extended Hückel molecular orbital calculations, which show clearly that orbital countercomplementarity exists on the part of the two magnetic bridge groups (azide and carboxylate), despite the very large azide bridge angle (119.5 degrees ).