Repository logo

Browsing by Author "Anderson, Oren, advisor"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Novel polynuclear copper compounds of halides and pseudo-halides
    (Colorado State University. Libraries, 1987) Reibenspies, Joseph Henry, author; Anderson, Oren, advisor; Elliott, C. Michael, committee member
    Mixed-valence compounds (one trinuclear (4) and two polymeric (5,6)) of copper(I,II) containing bridging cyano ligands and the ligands 1 (Pre-H) and 2 (cyclops) have been synthesized and characterized by single crystal X-ray diffraction. For 4, [Cu(1)(μ-NC)]2Cu(CN) · H2O, a= 9.723(2) Å, b = 10.908(2) A, c = 16.184(3) A, ɑ = 97.82(1) ᵒ, β = 103.64(2)ᵒ, γ= 92.21(2)ᵒ. Compound 5 ([Cu(1)(μ-NC)Cu(μ-CN)]n) occurs in three structural modifications. For 5a, a= 7 .755(2) Å, b = 13.179(3) Å, c = 16.508(5) A. For 5b, a= 7.878(2) Å, b = 8.418(2) Å, c = 25.874(4) Å, ~= 94.15(2)ᵒ. For 5c, a= 8.85(1) Å, b = 20.755(8) Å, c = 23.081(8) Å. For 6, [Cu(2)(μ-NC)Cu(μ- CN)·(l/2C6H6)]n, a= 11.667(2) Å, b = 8.962(2) Å, c = 19.895(5) Å,~= 97.58(2)ᵒ. The discrete molecules of 4 contain a trigonal planar [Cu(CN)3]^2- unit, which bridges between two [Cu(l)]+ complexes through two cyano ligands. Each of the polymeric species 5a, 5b, 5c, and 6 consists of a chain of [Cu(CN)2]- units joined by bridging cyano ligands. A cyano ligand also bridges between the copper(I) atoms of the chain and [Cu(1)]+ or [Cu(2)]+ complexes. The structures of three dinuclear copper(II) complexes, in which the Cu(II) atoms are bridged by azido and hydroxo ligands and by either the phenolate oxygen atom of N6OH or N6'OH have been determined by single crystal X-ray diffraction. The compound [Cu2(μ-l,3-N3)(N6O)](ClO4)2·THF (7) crystallized in the orthorhombic space group P 212121, with a= 12.977(2) Å, b = 13.188(3) Å, c = 22.033(6) Å. The compound [Cu2(μ-1,1-N3)(N6'O)](BF4)2·THF (8) crystallized in the orthorhombic space group P21cn, with a= 10.222(2) Å, b = 16.683(4) Å, c = 23.517(7) Å. The compound [Cu2(μ- OH)(N6'O)](BF4)i · THF (9a) crystallized in the monoclinic space group ?21/n, with a= 12.457(3) Å, b = 10.222(3) Å, c = 30.397(10) Å, β= 91.63(2). In these complexes each copper(II) atom is five-coordinate and is bound to three nitrogen atoms and the bridging phenoxo oxygen atom of either N60- or N6'0-. The fifth coordination site on each copper(II) atom is occupied by an atom of the bridging azido or hydroxo ligand. A dinuclear copper(II) complex which contains a bridging iodo ligand and two [Cu(2)]+ moieties has been characterized by X-ray crystallography. [Cu2(2)2I](ClO4) · 2MeOH (10) crystallized in the monoclinic system, space group C2/c, with Z = 4 and a= 21.564(3) Å, b = 11.920(2) Å, c = 14.831(2) Å, β = 96.83(1)ᵒ. Each of the copper(II) atoms in the dimer is coordinated to four nitrogen atoms of ligand 2 and to the bridging iodo ligand. The structures of two phases of the perchlorate salt of the copper(II) complex of 1 and methanol have been characterized by X-ray crystallography. For the room temperature phase {[Cu(1)]C1O4 · 1/2 MeOH}n (11a), a= 23.018(3) Å, b = 6.903(1) Å, c = 22.511(3) Å, β= 105.48(1)ᵒ. For the low temperature phase { [Cu(l)]ClO4 · 1/2 MeOH}i ((llb), a= 6.850(2) A, b = 11.886(3) A, c = 22.303(5) A, a= 75.26(2)0 , β= 88.97(2)ᵒ, γ= 73.38(2)ᵒ. When cooled, the crystalline solid 11 undergoes a reversible structural change. 11a is polymeric in nature, with bridging between copper atoms accomplished by an oxime oxygen atom of ligand 1. 11b is best described as dimeric.
  • Thumbnail Image
    ItemOpen Access
    Structural variations in metal ion complexes of the ligand EGTA⁴-
    (Colorado State University. Libraries, 1985) Schauer, Cynthia Karen, author; Anderson, Oren, advisor; Elliott, C. Michael, committee member
    Structural studies of several metal ion complexes with the tetraanion of the octadentate ligand, H^4EGTA (3,12-bis(carboxymethyl)-6, 9-dioxa-3, 12-diazatetradecanedioic acid), as well as the structure of H^4EGTA, have been performed by single crystal X-ray diffraction. Of particular interest was the structural basis for the large preference for EGTA^4- to bind calcium ion rather than (K(CaL^2-) ~= 10^6 magnesium ion = 10^6 (K(MgL^2-)), a preference which is similar to that exhibited by intracellular calcium binding proteins. The alkaline earth compounds, Ca[Ca(EGTA)]·(22/3)H2o, Sr[Ca(EGTA)] ·6H2O, Mg[Sr(EGTA)(OH2 )]·7H2o, Mg(Ba-(EGTA)]·(8/3)H2O·(1/3) (CH3) 2CO, and (Mg2(EGTA)(OH2 )6]·5H2O, have been structurally characterized. [Ca(EGTA)]2- is eight-coordinate and utilizes the full octadentate chelating capability of the EGTA^4- ligand. The ether oxygen atoms are bound at a shorter distance than the amine nitrogen atoms. EGTA^4 - is octadentate toward both the strontium and barium ions, which are nine- and ten-coordinate, respectively. The magnesium complex is dinuclear, utilizing each end of the EGTA^4- ligand as a tridentate iminodiacetate ligand; the ether oxygen atoms are not involved in coordination to the metal ion. Structures of EGTA^4 - chelates of metal ions that are commonly used as spectroscopic probes for calcium ion binding sites have also been determined. The cadmium chelate in Sr[Cd(EGTA)]·7H2 o is eight-coordinate, li k e [Ca(EGTA)]^2 -, but the amine nitrogen atoms are bound at shorter distances than the ether oxygen atoms. The metal ions in the structures of tripositive lanthanide ion complexes, Ca[Er(EGTA)(OH2)]2·12H2O and Ca[Nd(EGTA)- (OH 2 )]2·9H2O, are nine- and ten-coordinate, respectively. To further explore coordination modes of the EGTA^4 - ligand with smaller metal ions, where the ligand is not likely to be octadentate, structures of manganese and copper complexes of were determined. Sr[Mn(EGTA)] ·7H2O is isomorphous with the cadmium compound. As a result, the Mn(II) ion is eight-coordinate. The copper complex crystallizes as a dinuclear species, [CU2(EGTA)(OH2)2] ·2H2O, in which each end of the EGTA^4- ligand binds a copper(II) ion in a tetradentate fashion; the ether oxygen atom is bound in the apical position of the square pyramidal coordination sphere.