Mei-Cheng Shao

One- and two-dimensional framework materials constructed from the mixed Mo/V tetra-capped Keggin structure clusters and M(en)2 (M=Ni, Cu) complexes groups

Abstract Two novel low-dimensional framework materials, [ Ni ( en ) 2 ] 2 [ Ni ( en ) 2 Mo VI 6 V VI 10 O 40 ( V IV O 4 )]·4 H 2 O (1) and [ en ] 0.5 [ Cu ( en ) 2 ] 2 [ Cu ( en ) 2 Mo VI 6 Mo V 2 V IV 8 O 40 ( Mo IV O 4 )]·0.5 H 2 O (2), assembled hydrothermally, are constructed from the mixed Mo/V tetra-capped Keggin structure clusters linked through M(en)2(M=Ni,Cu) groups.

Synthesis and crystal structure of the heteropolyvanadate anion [AsV12P40(VO)2]9−

The structure of (Et 4 N) 3 H 6 [AsV 12 O 40 (VO) 2 ]·20H 2 O has been determined by single-crystal X-ray diffraction analysis. In the anion the central AsO 4 tetrahedron and 12VO 6 octahedra form the usual Keggin structure (α-isomer) and the remaining two VO 3+ groups occupy the cavities in the Keggin structure, where a two-fold axis passes to form trans -located tetragonal pyramidal caps.

X-Ray crystal structure of the unusual clathrate compound, [Mo36O110(NO)4(H2O)14]·52H2O

Reaction of sodium molybdate (Na2MoO4·2H2O) with hydroxylamine hydrochloride results in the formation of the red crystalline compound [Mo36O110(NO)4(H2O)14]·52H2O, which was characterized by photoelectron and i.r. spectroscopy, and a single-crystal X-ray structure analysis.

SYNTHESIS, STRUCTURE AND MAGNETIC PROPERTIES OF A POLYMERIC TRINUCLEAR MIXED-VALENCE MANGANESE MALONATE COMPLEX

Abstract A mixed-valence Mn III , Mn II , Mn III malonate polymeric cluster having a trimeric repeat unit, {[Mn II (H 2 O) 4 ] [Mn(malonate) 2 (H 2 O)] 2 } n , which is the first example of mixed-valence manganese carboxylate polymeric complex, has been prepared and characterized structurally. This complex behaves as an antiferromagnet and has a Neel temperature of ca 10 K.

Synthesis, spectrum and single crystal structure of a peroxovanadium complex of nitrilotriacetate ligand without water of crystallization, K2[VO(O2)NTA]

Abstract Crystals of the formula K2[VO(O2)NTA] with NTA = nitrilotriacetate have been prepared and characterized by IR and single-crystal X-ray diffraction methods. The structure of the anion of the complex shows that the vanadium atom has a distorted pentagonal bipyramidal environment surrounded by one oxo group, one peroxo group, three oxygen atoms and one nitrogen atom from the NTA ligand.

The remarkable polymetallate cluster: Crystal structure of Na6[H6Mo57Fe6O183(NO)6(H2O)18]·91H2O

The crystal structure of Na6[H6Mo57Fe6O189(NO)6(H2O)18]·91H2O has been determined and shown to consist of three 17-molybdate subunits connected by six FeO6 octahedra and three {Mo2O9} groups.

Crystal structure of a novel mixed valence MoV–MoVI heteropolymolybdate cluster: [H3O+]6[Mo57V6O183(NO)6(H2O)18]6–·89H2O

Reaction of sodium molybdate (Na2MoO4·2H2O) and ammonium metavanadate (NH4VO3) with hydroxylamine hydrochloride results in the formation of the title compound, which consists of three 19-molybdate subunits being connected by six VO6 octahedra, and six bridging water molecules; both the manner of linking of the VO6 octahedra to the 19-molybdate subunit and the formation of a polymetallate cluster containing 57 discrete Mo atoms, are hitherto unknown features.

A mesoscopic molecular superparamagnet: preparation, crystal structure and magnetic properties of [Mn12O12(O2CMe)4 (O2CEt)12(H2O)4] · 2H2O · 4EtCO2H with an S = 9 ground state

Abstract The first dodecanuclear manganese aggregate containing heterocarboxylate ligands [Mn12O12(O2CMe)4(O2CEt)12(H2O)4] (1) has been prepared and structurally characterized. The single crystal X-ray diffraction of 1 shows that it is similar to [Mn12O12(O2CR)16(H2O)4] ( 2a , R = Me or 2b , R = Ph ) in its skeletal structure but it has a different crystal structure. Primary magnetism studies imply that 1 has an S = 9 spin ground state. A clear hysteresis loop was also observed for a polycrystalline sample of 1 · 2H2O · 4EtCOOH, but there was no anomaly in susceptibility down to 1.5 K. The cluster 1 represents another example of nanometre-sized molecular superparamagnets without particle size distribution.

A water-soluble μ2-oxo bridged diiron complex with terminally ligated iminodiacetate chelating ligands

Abstract The novel oxo-centered dinuclear iron complex K4[Fe2O(IDA)4] (1) (IDA = iminodiacetate) was synthesized by the air-oxidation of ferrous iron in an aqueous solution in the presence of iminodiacetate and characterized by IR, magnetic susceptibility, and X-ray crystallography methods. The structure contains dimeric units where the two crystallographically equivalent iron centers are linked by a μ2-oxo bridge at a symmetric center of crystallography, forming a stick-like core, [Fe2O]4+, and have distorted octahedral environments each with one tridentate and one “bidentate-like” IDA ligands completing the coordination sphere. The iron centers are antiferromagnetically coupled in the cluster since they are bridged by the μ2-oxo oxygen atom in the center of symmetry and this was confirmed by the magnetic susceptibility study.

Self-assembly of a novel nanoscale giant cluster: [Mo176O496(OH)32(H2O)80]†

Reduction of an acidified solution of Na2MoO4·2H2O by iron powder results in the formation of the title compound [Mo176O16O480(OH)32(H2O)80]; the compound is tyre shaped and consists of sixteen {Mo8} subunits being linked by forty-eight MoO6 octahedra; remarkable features are the size and mass (which is of the order of a protein) and its nanodimensional cavity of ca. 3 nm in diameter.