L. S. Long

Anion-controlled formation of silver(I) complexes of a hexaazamacrocyclic Schiff base: Synthesis, structures and electrochemistry

Abstract Six silver(I) complexes of a macrocyclic Schiff Base (L) with different counter anions have been prepared and structurally characterized, where L is a hexaazamacrocyclic Schiff Base derived from the [2 + 2] condensation of terephthalaldehyde and 3-azapentane-1,5-diamine. [Ag2L(NO3)2] (1) crystallizes in the triclinic space group P1, with a = 7.705(7), b = 7.926(5), c = 12.06(1) A, α = 90.33(1), β = 95.13(1), γ = 104.07(1)°, V = 711(1) A3 and Z = 1. [Ag2L(NO3)2] (2) crystallizes in the monoclinic P21/n, with a = 7.714(3), b = 14.491(7), c = 11.821(6) A, β = 98.99(1)°, V = 1305(1) A3 and Z = 2. [Ag3L2(NO3)2] (C1O4) (3) crystallizes in the monoclinic space group C2/m, with a = 14.950(6), b = 13.258 (3), c = 27.399(16) A, β = 109.15(1)°, V = 2589(2) A3; and Z = 2. [Ag2L2](PF6)2 (4) crystallizes in the monoclinic space group P21/n, with a = 10.066(3), b = 9.846(5), c = 27.40(2) A, β = 92.81(8)°, V = 1712(2) A3 and Z = 4. [Ag4L(MeCH(OH)CO2)4] (5) crystallizes in the monoclinic P21/c, with a = 13.851(9)...

Crystal structure of sodium cobalt(III) 1,2,4-benzenetricarboxylate

Figure 1. 75% Probability ORTEP plot illustrating the geometry of the sodium atom in [Na][Co][C9Hi06]. Selected bond distances and angles: Nal-Ol = 2.486(3), Nal-ΟΙα = 2.328(4), Nal-036 = 2.575(3), Nal04b = 2.392(3), Nal-05c = 2.343(4), Nal-05</ = 2.381(4) Ä; Ol-Nal-Ola =145.0(2), 01-Nal-036 = 131.4(1), Ol-Na 1-046 = 85.1(1), 01-Nal-05c = 77.4(1), 01 -Na 1 -05d = 86.8(1), 01a-Nal-036 = 79.6(1), 01a-Nal-04A = 127.8(1), 01a-Nal-05c = 97.0(1), 01a-Nal-05i/ = 79.8(1), 036-Nal-04c = 85.8(1), 036-Nal-05</ = 126.7(1), 036-Nal-056 = 52.4(1), 04A-Nal-05c = 98.4(1), 046-Nal-05i/ = 110.9(1), 05c-Nal-05i/ = 145.3(2)°. Symmetry transformations used to generate equivalent atoms: a = χ 1/2, 3/2 -y, z;b = 3 / 2 x , \ / 2 +y, 1 z ; c = 3 / 2 x , 1/2 +y, -z-,d=\ -χ, 1 -y, -z.

A novel dinuclear zinc complex containing both imidazole and carboxylate groups as a possible model for serine/threonine protein phosphatase-1

Abstract A bis(μ-carboxylato-O)-bridged dinuclear zinc(II) complex of [(4-methyl-5-imidazol-1-yl)methylidene]-β-alanine has been synthesized and structurally characterized, in which the μ-carboxylato-O bridge and the metal–metal separation (3.263(4) A) resemble those in serine/threonine protein phosphatase-1 (PP1).

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

Abstract 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 −1 s −1 , respectively.

Crystal structure of a 3D coordination polymer: Sodium lanthanide terephthalate N, N-dimethylformamide solvate

Figure 1. ORTEP plot showing coordination environment of lanthanide and sodium ions at the 50% probability level. Hydrogen atoms are omitted for clarity. Selected bond distances and angles: Lai-Ol 2.5481(16), La I 0 3 2.5962(16), L a l 0 5 2.6078(18), La l -04 2.6322(17), La l -02b 2.6711(16), N a l 0 4 2.2361(15), N a l 0 2 e 2.3896(18), N a l 0 2 b 2.3896(18), Na l -05d 2.5054(17), Na l -La ld 3.6734(6) Ä, 0 1 La l -Ola 51.38(8), 0 1 L a l 0 3 77.99(6), 0 3 L a l 0 3 a 149.99(9), 0 1 L a l 0 5 127.84(6), 0 3 L a l 0 5 118.44(5), 0 5 L a l 0 5 a 147.76(9), 0 1 L a l 0 4 110.16(5), 0 3 L a l 0 4 49.65(5), 0 5 a L a l 0 4 110.90(5), 0 3 a L a l 0 4 a 49.65(5), 0 4 L a l 0 4 a 179.15(6), 0 1 L a l 0 2 b 160.70(6), 0 3 a L a l 0 2 b 122.74(6), 05 -La l 0 2 b 69.57(6), 0 1 L a l 0 2 c 134.34(6), 0 3 L a l 0 2 c 122.74(6), 0 5 a L a l 0 2 c 69.57(6), 0 4 L a l 0 2 c 113.62(5), 0 2 b L a l 0 2 c 48.57(7), 0 4 d N a l 0 5 d 77.10(6), 0 4 N a l 0 5 d 102.90(6), 0 2 e N a l 0 5 d 75.91(6)°. Symmetry transformation: a = -x+1, y, -z+3/2; b = -x+I, y-1, -z+3/2; c = x, y-I, z; d = -x+1, -v, -z+l; e = x, -y+1, z-l/2;f= -x+1, y+1, -z+3/2; g = x, y+1, z.

Crystal structure of a 3D coordination polymer: Zinc terephthalate hydrate

Figure 1. ORTEP plot of a portion of the ID zigzag chain formed in zinc terephthalate hydrate. The diagram was drawn at the 50% probability level and hydrogen atoms have been omitted for clarity. Selected bond distances and angles: Znl-Ol 1.9446(17), Zn l -03 1.978(3), Zn l -026 2.1829(17) Ä; O l -Zn l -O la 138.68(12), 01 -Zn l -03 110.66(6), 01-Znl -026 88.43(7), 03-Znl -02b 87.14(5), 01-Znl -02c 93.58(7), 02A-Zn 1 -02c 174.28(9)°. Symmetry transformation: a = x, y, z+5/2, b = x, -y+1, z+1/2, c = x, y+1, -z+2.

Crystal structure of bis(4-methyl-5-imidazolyl-5-carboxaldehyde)dichlorodizinc diperchlorate

Figure 1. ORTEP plot of the bis(4-methylimidazolyl-5-carboxaldehyde)dichlorodizinc dication of the title compound at the 50% probability level. Selected bond distances and angles: Znl-Nl 1.976(4), Znl-N3 1.983(4), Znl-Ol 2.494(4), Znl-02 2.633(4), Znl-Cll 2.346(2), Znl-Cll/ 2.443(2) A; Nl-Znl-N3 140.8(2), Nl-Znl-Ol 73.4(1), Nl-Znl-02 79.2(1), Nl-Znl-Cll 107.4(1), Nl-Znl-Cll; 97.2(1), N3-Znl01 82.1(1), N3-Znl-02 71.0(1), N3-Znl-Cll 104.1(1), N3-Znl-Cll/ 105.3(1), 01-Znl-02 91.1(1), 01Znl-Cll 93.3(1), Ol-Znl-Cll/ 170.5(1), 02-Znl-Cll 172.9(1), 02-Znl-Cll/ 85.9(1), Cll-Znl-Cll/ 90.6(1), Znl-CI 1-Znl/ 89.4(1)° Symmetry transformation: / = χ , 1 ν, 1 z .

Synthesis, crystal structure and cyclic voltammetry of square- pyramidal acetatoaqua [(4-methylimidazol-5-yl)methylene] histamine copper(II) perchlorate

The copper atom in acetatoaqua[[(4-methylimidazol-5- yl)methylene]histamine]-copper(II) perchlorate (1) is N,N,N-chelated by the [(4-methylimidazol- 5-yl)methylene]histamine [Cu–N=1.969(3) ∼2.019(3) Å] donor ligand. The aqua ligand occupies the apical site of the square-pyramidal coordination polyhedron [Cu–O= 2.365(3) Å], whose fifth site is occupied by the carboxy oxygen atom of the monodentate acetato anion [Cu–O=1.960(3)Å]. Cyclic voltammetry in MeCN and N,N-dimethylformamide (DMF) gives a voltage of −0.39 and −0.37 V versus s.c.e, which compares well with the value obtained for Cu,Zn superoxide dimuthase itself.

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.

The effect of the perturbation of hydrogen bonding on the Zn(II) coordination geometry: synthesis and structure of Zn(BIP) (H2O)(2) (ClO4)(2) (BIP=1,3-bis (4-methyl-5-imidazol-1-yl)ethylideneamino propane)

Abstract A polydentate ligand comprising imidazole donor 1,3-bis[(4-methyl-5-imidazol-1-yl)ethylideneamino]propane (BIP) was synthesized, and the crystal structure of its Zn(II) complex [Zn(BIP)(H2O)2](ClO4)2 has been reported, in which the Zn(II) atom adopts a distorted octahedral coordination geometry with the equatorial positions occupied by four nitrogen atoms of BIP and the axial positions by two aqua molecules. The effect of hydrogen bonding of the aqua ligand on the coordination geometry is discussed.