Qiutian Liu

Structural transformation mediated by o-, m-, and p-phthalates from two to three dimensions for manganese/phthalate/4,4′-bpy complexes (4,4′-bpy = 4,4′-bipyridine)

Three isomers of o-, m-, and p-phthalate are used to link together Mn centres, resulting in [Mn(phth)(H2O)x]n moieties (phth = phthalate dianion) with single-chain, double-chain and sheet structures, respectively, which predetermine the extended structures derived from the crosslinkage of 4,4′-bipyridine, and show the influence of isomerism of the phthalate on topological changes of the final polymers from two dimensional (2D) single-layer, double-layer to 3D network architectures. These structural changes in topology are correlated with the differences in the magnetic and optical properties of the polymers.

Framework variations in Mn(II)–organic coordination polymers: solvent templated formation and characterisation of 1D zigzag and straight chain network isomers

Hydrothermal reaction of manganese carbonate with 4,4′-biphenyldicarboxylic acid (H2bda) and 1,10-phenanthroline (phen) affords coordination polymers, [Mn(bda)(phen)(H2O)]n·npy·nH2O (1·npy·nH2O, 1a), [Mn(bda)(phen)(H2O)]n·2npip (1·2npip, 1b) and [Mn(bda)(phen)]n (2). The polymer 1 crystallizes into either 1D zigzag chain or straight chain structures depending on the crystallisation solvents used, and both of them stack into a 3D guest-filled porous framework via inter-chain interactions, whereas the polymer 2 organizes into a 3D ligand-filled porous coordination framework in the absence of suitable guests. The polymer 1 represents an unusual example of network isomers formed via the templating of structurally dissimilar but closely related organic guests.

Synthesis, characterization and crystal structures of the cobalt(II) and iron(II) complexes with an octadentate ligand, 1,4,7,10-tetrakis(2-pyridylmethyl)-1,4,7,10-tetraazacyclododecane (L), [ML]2+

Abstract The potential octadentate ligand, 1,4,7,10-tetrakis(2-pyridylmethyl)-1,4,7,10-tetraazacyclododecane (L), gives iron(II) and cobalt(II) complexes of general formula [ML](ClO4)2·nH2O (n=1 or 0.5). The crystal and molecular structures of the complexes have been determined by single-crystal X-ray analysis. The complex [FeL](ClO4)2·H2O can be considered as octacoordinated with two semicoordinated bonds. The complex [CoL](ClO4)4·0.5H2O is six-coordinated with approximate octahedral geometry.

Aggregation of tetranuclear Mn building blocks with alkali ion. Syntheses, crystal structures and chemical behaviors of monomer, dimer and polymer containing [Mn4(µ3-O)2]8+ units

Aggregation of tetranuclear Mn(4)O(2) building blocks with alkali ion was studied. Several Mn(iii) complexes containing [Mn(4)O(2)(AcO)(7)(pyz)(2)](-) (pyz = pyrazinate) anion(s) were obtained from an assembly system containing Mn(ii), MnO(4)(-), HOAc and Hpyz (Napyz or Kpyz). These [Mn(4)O(2)](8+) complexes have monomeric (1 and 2), dimeric (4 and 5) and one-dimensional chain () structures of which alkali metal ion connects the Mn ions of adjacent [Mn(4)O(2)](8+) units through mu(1,1)- and mu(1,3)-carboxylate bridges. Complexes 2 or 3 were converted into [Mn(12)O(12)(AcO)(16)(H(2)O)(4)] in EtOH solution in the presence of HOAc. However, in MeOH solution, a coordination polymer [Mn(2)(HCOO)(4)(H(2)O)(4)](n) was obtained accompanying the oxidation of MeOH to become HCHO and HCOOH. Tracing the (1)H NMR spectra of 2 or 3 in CD(3)OD, the disappearance of the resonance signals in 3 h indicated the decomposition of the [Mn(4)O(2)](8+) cores. Complex 2 exhibits its proton NMR signals in CDCl(3) which are similar to those of its pic analogue but accompany downfield shift to various extents for all the corresponding signals. Variable-temperature magnetic susceptibilities of complexes 2-5 in the range 5-300 K were recorded and were fitted for an Mn(4)O(2) butterfly core, giving the fitting parameters J(bb) = -2.67 to -3.76 cm(-1) and J(wb) = -1.16 to -3.14 cm(-1). Small J values indicate weak antiferromagnetic coupling interactions of the Mn(iii) sites and the spin ground states are considered as S(T) = 0 based on the J(bb)/J(wb) ratio approximately 1 for these complexes. The ESR spectra were recorded for complex 2 in dual-mode at liquid-helium temperatures and no obvious signal could be found. The addition of p-cresol gives rise to the reduction of the [Mn(4)O(2)](8+), resulting in observable signals.

Palladium complexes with simultaneous O:S coordination, syntheses, structures and characterization of complexes with 2-mercaptophenol or 2-mercaptopyridine N-oxide

Abstract Complexes (Et4N)2[Pd2(mp)2(Hmp)2] (1) and [Pd(mpo)2] (2) synthesized from the reactions of palladium chloride with 2-mercaptophenol (H2mp) and 2-mercatopyridine N-oxide (Hmpo) or 2,2′-dithiobis(pyridine N-oxide) (dtpo), respectively, have been characterized by X-ray diffraction analyses and studied by IR, Raman, 1H and 13C NMR, and EI-MS techniques. The palladium atoms in the two compounds are in square planar environments. The average PdO distances are 2.009 A and 2.043 A for 1 and 2, respectively. The results of EHMO calculations show that the PdO bonds are weaker than the PdS bonds in both compounds and large delocalized π bonds extend in the (mp)2Pd2S2 plane in 1 and in the Pd(mpo)2 plane in 2. The reaction of [Ni(mpo)2] with [Pd(COD)Cl2] led to the formation of 2 also, which implies that the bidentate O:S ligand mpo readily transfers from the NiII to the PdII ion.

A trimanganese cluster-based 2D layer framework with facile single-crystal-to-single-crystal transformation to afford a 1D chain structure

A new isophthalate manganese(II) coordination polymer, [Mn3(ip)3(bipy)2]n·2nH2O (1) (H2ip = isophthalic acid and bipy = 2,2′-bipyridine), with a 2D layer structure built up from isophthalato-linking trimanganese clusters, is obtained by refluxing a weakly basic solution containing bipy, Mn(OAc)2·4H2O, H2ip, and triethylamine. Both the complex and the dehydrated materials show irreversible water adsorption at room temperature, accompanied by facile single-crystal-to-single-crystal structural transformation forming a 1D chain-like coordination polymer upon rehydration, [Mn(ip)(bipy)(H2O)2]n·nH2O (2). The thermogravimetric behavior and magnetic properties of both the complexes are examined.

Synthesis and characterization of a family of tetranuclear manganese(III) phosphonate complexes

Four tetranuclear manganese(III) complexes containing phosphonate ligands (RPO32−, R = Me, Et and n-Bu), [Mn4O2(MePO3)2(O2CMe)4(bpy)2]·4MeCOOH (1), [Mn4O2(EtPO3)2(O2CMe)4(bpy)2]·7H2O (2), [Mn4O2(n-BuPO3)2(O2CMe)4(bpy)2]·4H2O·(COOH)2 (3) and [Mn4O2(MePO3)2(O2CPh)4(phen)2]·4PhCOOH·2MeCN (4), have been synthesized and characterized by IR spectroscopy, ESI-MS spectrometry, electrochemical analysis, magnetic measurements and TGA. The X-ray analysis shows that the four complexes all have one [Mn4(μ3-O)2]8+ core with four coplanar Mn atoms disposed in an extended “butterfly-like” arrangement and two O atoms triply bridging each “wing”, and the peripheral ligation is provided by four μ2-MeCO2− or four μ2-PhCO2−, two terminal bpy or phen (bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) groups at both ends of the molecule, and two bicapping μ3-phosphonate ligands, which each binds to three manganese centers above and below the plane. The cyclic voltammetry of 1 and 3 each displays four reduction and one oxidation processes, of which the four reduction processes are possibly attributed to the reduction of four MnIII of the compounds to MnII. The ESI-MS data indicate that the family of complexes are stable in solution. Magnetic susceptibility measurements reveal that compounds 1 and 3 display antiferromagnetic interactions between the adjacent MnIII ions mediated through the μ3-O, O–C–O and O–P–O bridges.

Preparation and crystal structure of a new Cu (II) complex derived from the desulfurization of N-(p-nitrophenyl)-N′-ethoxycarbonyl-thiourea

A novel copper (II) complex, CuL 2 (HL= N -ethoxycarbonyl- [methoxyl- ( p -nitrophenyl)amino]aldimine), derived from the desulfurization of N - ( p -nitrophenyl)- N ′-ethoxycarbonyl-thiourea (H 2 pet) has been synthesized and crystallographically characterized. The Cu (II) atom is in a four-coordinate square planar geometry contributed by two deprotonated amine N and two carbonyl O atoms from two L groups with Cu–N and Cu–O bond lengths of 1.968 (3) and 1.926 (2) A, respectively. In terms of the ligand H 2 pet, its structural asymmetric unit contains two crystallographically independent molecules formed by S···H hydrogen bonds.

(N-CnH2n-1)-1,3-Azapropanedithiolate (n=5, 6, 7)-bridged diiron complexes as mimics for the active site of FeFe -hydrogenases: the influence of the bridge on the diiron complex

To further understand the effects of 1,3-azadithiolate (ADT) bridges on the structures and properties of diiron complexes, a novel family of (N-CnH2n−1)-1,3-azapropanedithiolate-bridged diiron complexes [Fe2(CO)6(CH2S)2N–CnH2n−1] (n = 5, 6, 7) and their PMe3-disubstituted complexes [Fe2(CO)4(PMe3)2(CH2S)2N–CnH2n−1] (n = 5, 6, 7) were synthesized as mimics of [FeFe]-hydrogenases. Our studies suggest that the coordination configurations, CO stretching frequencies, 1H and 31P NMR signals, redox potentials and electrocatalytic H2-production processes of diiron complexes are closely pertinent to the electron-donating abilities and steric chemistry of the ADT bridges.

Synthesis, structural characterization and magnetic properties of 2-pyrazinecarboxylate manganese compounds [Mn(pyz)2(H2O)4] and [MnCl(pyz)(H2O)]n (pyz = 2-pyrazinecarboxylate)

Two pyz complexes [Mn(pyz)(2)(H2O)(4)] (1) and [MnCl(pyz)(H2O)] (2) have been synthesized and structurally characterized. Complex 1 contains an eight-coordinate Mn(II) ion with square anti-prismati ...