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CuII Compounds (cuii + compound)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

A Theoretical Study of the Exchange Coupling in Hydroxo- and Alkoxo-Bridged Dinuclear Oxovanadium(IV) Compounds

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2004
Antonio Rodríguez-Fortea
Abstract A density functional study of exchange coupling in hydroxo- and alkoxo-bridged dinuclear oxovanadium(IV) compounds is presented. Coupling constants calculated for full unmodeled structures are in good agreement with experimentally reported values, confirming the ability of the computational strategy used in this work to predict the exchange coupling in dinuclear VIV compounds. The influence of the configuration of the [VO(,-OR)2VO]2+ core in compounds with two edge-sharing octahedrally coordinated oxovanadium(IV) centers, of the nature of the terminal ligands and of structural distortions on the coupling constant have been analyzed through model calculations. The results indicate that the coupling constant is less affected by these factors than for hydroxo- and alkoxo-bridged CuII compounds. The calculations support the orbital models usually employed in qualitative interpretations of magneto-structural correlations, showing good correlations between the calculated coupling constants and the overlap between the two magnetic orbitals or the square of the orbital gap. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Synthesis and Characterization of Copper Complexes Containing the Tripodal N7 Ligand Tris{2-[(pyridin-2-ylmethyl)amino]ethyl}amine (=N,-(Pyridin-2-ylmethyl)- N,N -bis{2-[(pyridin-2-ylmethyl)amino]ethyl}ethane-1,2-diamine): Equilibrium, Spectroscopic Data, and Crystal Structures of Mono- and Trinuclear Copper(II) Complexes

HELVETICA CHIMICA ACTA, Issue 9 2005
Christian Gérard
The stability constants of the CuII chelates with the tripodal heptadentate ligand tris{2-[(2-pyridylmethyl)amino]ethyl}amine (=N,-(pyridin-2-ylmethyl)- N,N -bis{2-[(pyridin-2-ylmethyl)amino]ethyl}ethane-1,2-diamine; tpaa), determined by potentiometry and UV spectrometry, show the formation of [Cu(tpaaH)]3+ and [Cu(tpaa)]2+ species. In the solid state, two mononuclear CuII compounds, [Cu(tpaa)](PF6)2 (1) and [Cu(tpaaH)](ClO4)3,H2O (2), and one trinuclear [Cu3(tpaa)2(ClO4)2](ClO4)4,2,H2O (3) complex were isolated and characterized by IR, UV/VIS, and EPR spectroscopy. An X-ray structure of the mononuclear protonated complex 2 shows that the Cu2+ ion has a distorted square-pyramidal geometry (,=0.21). and the proton is bound to the secondary-amine function of one uncoordinated arm of the tripod ligand (Fig.,4). The crystal lattice for 2 is stabilized by the H-bonds between the N-atom of the free pyridinyl group with the proton of the free secondary-amine function of the neighboring molecule. The linear trinuclear complex 3 consists of two entities of the pyramidal mononuclear complex 1 bound to the third central Cu2+ ion by the free unprotonated arms of the ligands in equatorial position (Fig.,5). The octahedral geometry of the third CuII atom is achieved by two perchlorate anions in the axial positions. The redox properties of 1,3 compounds was examined by cyclic voltammetry. [source]

Three-Dimensional Lanthanide(III),Copper(II) Compounds Based on an Unsymmetrical 2-Pyridylphosphonate Ligand: An Experimental and Theoretical Study

CHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2007
Yun-Sheng Ma
Abstract Based on an unsymmetrical 2-pyridylphosphonate ligand, two types of LnIII,CuII compounds with three-dimensional structures were obtained under hydrothermal conditions, namely, Ln2Cu3(C5H4NPO3)6,4,H2O (1,Ln; Ln=La, Ce, Pr, Nd) and Ln2Cu3(C5H4NPO3)6 (2,Ln; Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho). Compounds 1,Ln are isostructural and crystallize in chiral cubic space group I213. In these structures, each Ln ion is nine-coordinate and has a tricapped triprismatic geometry, while each Cu center is six-coordinate with an octahedral environment. The {LnO9} polyhedra and {CuN2O4} octahedra are connected by edge sharing to form an inorganic open framework structure with a 3-connected 10-gon (10,3) topology in which the Ln and Cu atoms are alternately linked by the phosphonate oxygen atoms. Compounds 2,Ln are isostructural and crystallize in trigonal space group R. In these structures, the {LnO6} octahedra are triply bridged by the {CPO3} tetrahedra by corner sharing to form an infinite chain along the c axis. Each chain is connected to its six equivalents through corner sharing of {CPO3} tetrahedra and {CuN2O2} planes to form a three-dimensional framework structure in which the Ln and Cu atoms are linked purely by O-P-O units. The formation of these two types of structures is rationalized by quantum chemical calculations, which showed that both the lanthanide contraction and the electron configuration of CuII play important roles. When CuII was replaced by ZnII, only the first type of compounds resulted. The magnetic properties of complexes 1,Ln and 2,Ln were investigated. The nature of LnIII,CuII (Ln=Ce, Pr, Nd) interactions is illustrated by comparison with their LnIII,ZnII analogues. [source]

Compressed Octahedral Coordination in Chain Compounds Containing Divalent Copper: Structure and Magnetic Properties of CuFAsF6 and CsCuAlF6

CHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2004
Zoran Mazej Dr.
Abstract Crystal structures and magnetic investigations of CuFAsF6 and CsCuAlF6 are reported. Together with KCuAlF6, these appear to be the only examples of Jahn,Teller pure CuII compounds containing only one type of ligand that exhibits a compressed octahedral coordination geometry. The Rietveld method has been used for refining the CsCuAlF6 structure based on neutron powder diffraction data at 4 K. The compound crystallizes in space group Pnma (no. 62) with a=7.055(1), b=7.112(1), c=10.153(1) Å and Z=4 at 4 K. The structure is built from infinite [CuF5]n3n, chains of [CuF6]4, octahedra running along the [1,0,0] direction and (AlF6)3, octahedra connected by corners in the trans position, thus giving rise to chains oriented along the [0,1,0] direction. Single crystals of CuFAsF6 were prepared under solvothermal conditions in AsF5 above its critical temperature. The structure was determined from single-crystal data. CuFAsF6 crystallises in the orthorhombic space group Imma (No. 74) with a=10.732(5), b=6.941(3), c=6.814(3) Å and Z=4 at 200 K. The structure can also be described in terms of one-dimensional infinite [CuF5]n3n, chains of tilted [CuF6]4, octahedra linked by trans -vertices running along the b axis. The [CuF5]n3n, chains are connected through [AsF6], units sharing joint vertices. The compressed octahedral coordination of CuII atoms in CuFAsF6 and CsCuAlF6 compounds at room temperature is confirmed by Cu K-edge EXAFS (extended x-ray absorption fine structure) analysis. For both compounds strong antiferromagnetic interactions within the [CuF5]n3n, chains were observed (,p=,290±10 K and ,p=,390±10 K for CuFAsF6 and CsCuAlF6, respectively). The peculiar magnetic behaviour of chain compounds containing divalent copper at low temperature could be related to uncompensated magnetic moments in the one-dimensional network. [source]