Cungen Zhang

Structural Study and Solution Integrity of Dioxomolybdenum(VI) Complexes with Tridentate Schiff Base and Azole Ligands

Four new molybdenum complexes (Mo VI O2(L 1 )(Him)) (1), (Mo VI O2(L 1 )(3-MepzH) (2), (Mo VI O2(L 2 )(3-MepzH)) (3), and ((Mo VI O2)2(µ-L 3 )(MeOH)2 )( 4) were synthesized and characterized by IR, NMR, ESI-MS, and single-crystal structure analysis (H2L 1 2-(salicylideneamino)-2-methyl-1-propanol, H2L 2 2-(3- methoxysalicylideneamino)-2-methyl-1-propanol, H4L 3 1,7- bis(salicylidene)dihydrazide malonic acid, Him imidazole and 3- MepzH 3-methylpyrazole). In all four structures the molyb- denum atom has a distorted octahedral coordination with the three meridional donor atoms from the Schiff base di- or tetraanion (L 1,2 ) 2 /(L 3 ) 4 and one oxo group occupying the sites of the equa- torial plane. The other oxo group and the azole or methanol mol- ecule occupy the apical sites. In 1-3 two centrosymmetrically related

Six-coordinated zinc complexes: [Zn(H2O)4(phen)] (NO3)2·H2O and [ZnNO3(H2O)(bipy)(Him)]NO3 (phen = 1,10-phenanthroline, bipy = 2,2′-bipyridine, and Him = imidazole)

Two novel six-coordinated zinc complexes, tetra-aqua(1,10-phenanthroline)zinc dinitrate monohydrate, [Zn(H2O)4(phen)](NO3)2·H2O (1) and aqua(2,2′-bipyridine)(imidazole)-nitratozinc nitrate, [ZnNO3(H2O)(bipy)(Him)]NO3 (2) were prepared. Compound 1 crystallizes in the monoclinic space group P21/c with a = 8.780(4), b = 13.609(4), c = 15.368(5) Å, β = 93.86(2)°C, V = 1832.1(12) Å3. In 1, a phenanthroline molecule chelates the zinc atom and four water molecules complete the octahedral geometry around the metal. Compound 2 crystallizes in the monoclinic space group P21/n with a = 7.250(1), b = 24.554(4), c = 10.258(2) Å, β = 107.880(10)°, V = 1737.9(5) Å3. In 2, a bipyridine molecule and a nitrate anion chelate the zinc atom. An imidazole molecule and a water molecule then complete the six-coordinated geometry around zinc. The intermolecular packing is controlled by hydrogen bonding, especially in 1 and by π stacking. The thermal stability of the compounds and the loss of water molecules and ligands was monitored by a thermogravimetric study.

Synthesis, crystal structure and properties of di-μ2-alkoxo bridged binuclear manganese(III) Schiff base complexes

Preparation and isolation of the dimeric manganese(III) complex, [Mn2(Salpa)2(H2O)2Cl2] · 2DMF, (1), was accomplished by air oxidation of a solution containing MnCl2 · 4H2O, Et3N and H2Salpa** in DMF. Complex (2), [Mn2(Salpa)2(H2O)2(N3)2] · 2EtOH was obtained by reacting (1) or [Mn2(Salpa)2(AcO)2], (3), with NaN3 in EtOH. The crystal structure of (1) was determined by X-ray crystallography. It consists of discrete six-coordinate dimeric manganese molecules with unsupported alkoxido bridges, a rare example of a chloride- and water-containing manganese model complex for the oxygen-evolution center of photosystem II. The Mn–O and Mn–N distances are in good agreement with those found for other manganese(III) Schiff base complexes. The Mn–Cl and Mn–O(water) distances of 2.5577(11) and 2.323(3) Å, respectively are due to Jahn-Teller distortion at the d4 metal center. The Mn ⋯ Mn distance is 3.0077(12) Å. In the crystal, the distance between the H2O molecule and the O atom of DMF of 2.692(5) Å suggests hydrogen binding interactions. A t.g. study of (1) confirmed that the complex contains DMF molecules. Magnetic measurements on (1) and (2) reveal the presence of antiferromagnetic spin-exchange interactions between the manganese(III) ions.

SYNTHESIS, CRYSTAL STRUCTURE AND PROPERTIES OF A MANGANESE(III) SCHIFF-BASE COMPLEX : MN(VANEN)(HIM)(H2O)MN(VANEN)(HIM)2(CLO4)2.4H2O (H2VANEN = N, N'- BIS(METHOXYSALICYLIDENE)-1,2-DIAMINOETHANE)

A novel manganese(III) complex, [{Mn(vanen)(Him)(H2O)}(Mn(vanen)(Him)}](ClO4)2 · 4H2O [H2vanen = N,N′-bis(methoxysalicylidene)-1,2-diaminoethane], has been synthesized and characterized by elemental analysis, i.r. spectroscopy, t.g.a. and by an X-ray single crystal study. The complex consists of two sets of cations: [Mn(vanen)(Him)(H2O)]+ (A) and [Mn(vanen)(Him)2]+ (B), each of which has six-coordinate geometry, significantly elongated due to the Jahn-Teller distortion at the d4 manganese(III) center. The presence of lattice and coordinate water molecules are also confirmed by the t.g. study and the i.r. spectra.

A carboxyl­ato-supported alkoxo-bridged dimanganese(III) complex: bis(μ-benzoato-O:O′)­bis­[3-(3-meth­oxy­salicyl­idene­amino)­propanolato-O,N,O′:O′]­di­manganese(III)

The title compound, [Mn2(C11H13NO3)2(C7H5O2)2], is a centrosymmetric dinuclear manganese(III) complex in which the two Mn atoms are bridged by two alkoxo groups and supported by two carboxylate groups, with an Mn.Mn distance of 2.8720 (15) A.

Synthesis, crystal structure and properties of a novel di-μ2-aqua bridged binuclear manganese(III) Schiff base complex [Mn(vanen)(H2O)2]2(ClO4)2 · 2H2O

The preparation and isolation of the binuclear manganese(III) complex, [Mn(vanen)(H2O)2]2(ClO4)2 · 2H2O was accomplished by air oxidation of a solution containing H2vanen**, Et3N, and Mn(ClO4)2 · 6H2O in absolute EtOH. The crystal structure of complex was determined by X-ray crystallography, and consists of two molecules bridged by two water molecules through hydrogen bonding. The manganese atom is six-coordinate and presents a distorted octahedral coordination sphere, which consists of the two imine N atoms and two phenolic O atoms of vanen2− ligand in the equatorial plane, with Mn–N bond distances of 1.975 and 1.987 Å, and Mn–O distances of 1.867 and 1.876 Å, respectively. The non-bonding interatomic Mn⋯Mn distance is 4.79 Å. In the axial direction, the elongated Mn–O(H2O) bond distances of 2.255 and 2.381 Å, respectively, are due to Jahn–Teller distortion at the d4 metal center. The presence of lattice and coordinate water molecules were also confirmed by the t.g. study and the i.r. spectra. Upon irradiation using visible light in water in the presence of p-benzoquinone, the complex demonstrates its ability to split water.

Crystal structure of [Mn2(III)(salpa)2Cl2(H2O)2] (H2salpa = 1-(salicylaldeneamino)-3-hydroxypropane)

The manganese complex, (Mn2(III)(salpa)2Cl2(H2O)2], has been prepared and its structure determined using x-ray crystallography. The dimer is a di-μ2-alkoxo complex which is a six-coordinate manganese dimer with unsupported alkoxide bridges and a rare example of a chloride- and water-containing manganese dimer. The complex crystallizes in the monoclinic space group P21/c with a = 9.315(5), b = 11.130(4), c = 11.637(5) Å, β = 104.33(3)°, V = 1169.0(9) Å3, and Z = 2. The structure comprises discrete binuclear clusters in which the metal atoms are bridged by two alkoxo oxygens of the salpa2− ligands. The Mn—O and Mn—N distances are in good agreement with those found for other manganese(III) Schiff base complexes. The Mn—Cl and Mn—O3 distances are 2.585(2) and 2.371(2) Å, respectively, and the Mn ··· Mn distance is 3.001(1) Å. In the crystal, there are two types of hydrogen bonding between the H2O molecule and the Cl atom with Cl ··· H(H2O) distance of 2.33(6) (intramolecule: −1 + x, y, −1 + z) and 2.68(6) Å (intermolecule: −1 + x, 0.5−y, −0.5 + z).

Tetraaqua(1,10-phenanthroline)zinc(II) sulfate dihydrate

A novel monomeric phenanthroline (phen) zinc complex, [Zn(C 12 H 8 N 2 )(H 2 O) 4 ]SO 4 .2H 2 O, has been characterized by X-ray analysis. The Zn atom is coordinated in a slightly distorted octahedral geometry by two N atoms from 1,10-phenanthroline and four O atoms from water ligands. The Zn-N bond lengths are in the range 2.136 (3)-2.156 (2) A and the Zn-O bond lengths are in the range 2.083 (2)-2.130 (2) A. Hydrogen bonds stabilize the structure.

SYNTHESIS AND CHARACTERIZATION OF MANGANESE(III) HYDROXYL-CONTAINING SCHIFF-BASE COMPLEXES: [Mn(III)(Hvanpa)2(NCS)] AND [Mn(III)(Hvanpa)2]Cl · H2O (H2vanpa ˭ 1-(3-METHOXYSALICYLALDENEAMINO)-3-HYDROXYPROPANE)

Abstract The manganese complexes, [Mn(III)(Hvanpa)2(NCS)] (1) and [Mn(III)(Hvanpa)2]Cl · H2O (2), have been prepared and the crystal structure of complex 2 determined using X-ray crystallography. The monomeric complex has a six-coordinate octahedral geometry. The complex crystallizes in the triclinic space group P-1 with a = 11.446(5) Å, b = 12.782(6) Å, c = 9.023(3) Å, α = 93.92(3)°, β = 97.05(3)°, γ = 65.42(2)°, V = 1169.0(9) Å3 and Z = 2. The Mn-O and Mn-N distances in the equatorial plane are in agreement with those found for other manganese (III) Schiff-base complexes. In the axial direction, the Mn-O distances of 2.256(3) and 2.236(3) Å, respectively, are about 0.4 Å longer than those in the equatorial plane due to Jahn-Teller distortion at the d 4 manganese(III) center. In the crystal, each chloride ion is linked through hydrogen bonding with two hydrogen atoms from the coordinated hydroxyl groups at the apical site. The lattice water molecules also interact with the phenolic oxygen atoms through hydrogen bonding.

Crystal structure of 1-chloroanthraquinone

The X-ray crystal structure of 1-chloroanthraquinone is determined. The compound C14H7O2Cl, is monoclinic in P21(#4) with a = 7.763(1), b = 3.973(2), c = 16.947(1) Å,β = 95.13(1)°, V = 520.6(3) Å3, Dcalc = 1.548 g/cm3, and Z = 2. In the molecular structure, the Cl atom is obviously repelled by O(1). The major force of crystal formation comes from aromatic ring stacking and C–H-aromatic interaction.