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Synthesis, spectroscopic studies and structures of molybdenum(VI) complexes with homocitrate complexes with homocitrate are reported. Results show that the homocitrate ligand trapped by tetranuclear molybdate coordinates to the molybdenum(VI) atom through alpha-alkoxy and alpha-, beta-carboxy groups.

A novel dimeric dioxomolybdenum(VI) citrate complex, K[{MoO2)(sub 2-)(OH)(H2cit)(sub 2)].4H2O (1), with weak coordination of beta-carboxylic acid groups and the first structural example of an oxomolybdenum(V) citrate complex, (NH4)(sun 6)[Mo2O4(cit)(sub 2)].3H2O (2) (H2cit = citric acid), are isolated in a very acidic solution and neutral conditions, respectively. Protonation of a carboxyl group will weaken the coordination of molybdenum(VI) citrate and there are some dissociations of molybdenum(VI/V) citrate complexes based on (super 13)C NMR observations in solution.

Novel silver(I) alkynyl cluster complexes are synthesized by reacting soluble polymeric precursors with bipyridine ligands. The control of the nuclearity is achieved by varying the molar ratio of the reactants and by using different types of anions.

Synthesis, spectroscopic studies and structures of molybdenum(VI) complexes with homocitrate complexes with homocitrate are reported. Results show that the homocitrate ligand trapped by tetranuclear molybdate coordinates to the molybdenum(VI) atom through alpha-alkoxy and alpha-, beta-carboxy groups.

From neutral solutions, dimeric 1,3-propanediaminetetraacetato lanthanides (NH4)2[Ln2(1,3-pdta)2-(H2O)4]·8H2O [Ln = La, 1; Ce, 2] and K2[Ln2(1,3-pdta)2(H2O)4]·11H2O [Ln = La, 3; Ce, 4] (1,3-H4pdta = 1,3-propanediaminetetraacetic acid, C11H18N2O8) were isolated in high yields. The reaction of excess strontium nitrate with 1 resulted in the formation of a two dimensional coordination polymer [La2(1,3-pdta)2(H2O)4]n·[Sr2(H2O)6]n·[La2(1,3-pdta)2(H2O)2]n·18nH2O (5) at 70 °C. Complexes 1-4 show a similar central molecular structure. The lanthanide ions are coordinated by two nitrogen atoms, four carboxy oxygen atoms from one 1,3-pdta ligand, two from the neighboring 1,3-pdta ligand forming a fourmembered ring and two water molecules. Complex 5 has two kinds of dimeric lanthanum unit and extends into a 2D coordination polymer through strontium ions and bridged oxygen atoms, and forms a fourteen membered ring linked by oxygen atoms from carboxy groups of pdta. Complexes 1-4 are soluble in water. The 13C{¹H} NMR experiments for complex 1 were tested in solution. Thermal products from 1 and 5 show good catalytic activities towards the oxidative coupling reaction of methane (OCM). The conversion of methane and selectivity to C2 reached 29.7% and 51.7% at 750 °C for the product of 5. From TGA, XRD and SEM analyses, the thermal products from 1 and 5 are rod- and poly-shaped, which are assigned as lanthanum oxocarbonate and a mixture of La2O3, SrCO3 and La2O2CO3 for 1 and 5, respectively. The precursor method is favorable for the formation of regular shaped mixed oxides. [ABSTRACT FROM AUTHOR]

A new type of thermally stable chelate {La(H2O)4[La(1,3-pdta)(H2O)]3}n·12nH2O (1) [1,3-H4pdta=CH2[CH2N(CH2CO2H)2]2] with an open-channel shows significant and unusual solvent transport properties and demonstrates a use for low-pressure desalination, which is constructed by cheap and available lanthanum salt and 1,3-propanediaminetetraacetate. The chelate could be converted reversibly to its trihydrate {La(H2O)4[La(1,3-pdta)(H2O)]3}n·3nH2O (1a), dehydrated product {La(H2O)4[La(1,3-pdta)-(H2O)]3}n (1b) and ethanol adduct {La(H2O)4[La(1,3-pdta)(H2O)]3}n·3nH2O·3nEtOH (1c). The latter nano-confined ethanol shows a remarkable downfield shift (Δδ = 6.0 ppm) for the methylene group in the solid 13C NMR spectrum compared with that of the free EtOH. Crystal 1 with a regular hexagonal appearance can be used directly for saline water desalination on a small-scale at an ambient temperature, demonstrating a low energy consumption and environmentally friendly method. This is attributed to the 10.0 Å hydrophobic open-channel containing water nanotubes (WNTs, Φ = 4.2 Å). The nano-confined WNTs can be removed at a low temperature (45 °C). [ABSTRACT FROM AUTHOR]

A 1,10-phenanthroline (phen) chelated molybdenum(VI) citrate, [(MoO2)2O(H2cit)(phen)(H2O)2]·H2O (1) (H4cit = citric acid), is isolated from the reaction of citric acid, ammonium molybdate and phen in acidic media (pH 0.5–1.0). A citrato oxomolybdenum(V) complex, [(MoO)2O(H2cit)2(bpy)2]·4H2O (2), is synthesized by the reduction of citrato molybdate with hydrazine hydrochloride in the presence of 2,2′-bipyridine (bpy), and a monomeric molybdenum(VI) citrate [MoO2(H2cit)(bpy)]·H2O (6) is also isolated and characterized structurally. The citrate ligand in the three neutral compounds uses the α-alkoxy and α-carboxy groups to chelate as a bidentate leaving the two β-carboxylic acid groups free, that is different from the tridentate chelated mode in the citrato molybdate(VI and V) complexes. 1 and 2 in solution show obvious dissociation based on 13C NMR studies. [ABSTRACT FROM AUTHOR]