Hanqin Liu

Fabrication of boehmite AlOOH and γ-Al2O3 nanotubes via a soft solution route

The tubular form of crystalline boehmite AlOOH was fabricated using AlCl3·6H2O as the alumina precursor in the presence of N-cetyl-N,N,N-trimethylammonium bromide surfactant, and tubular γ-Al2O3 was obtained by calcination of boehmite AlOOH at 520 °C.

Syntheses and characterization of copper(II) complexes of bis(acetylacetone)trimethylenediimine

Abstract Copper(II) complexes [Cu(acactn)H2O]2 (1) and [Cu2(acactn)2KClO4]2 (2), where H2acactn is a tetradentate Schiff base bis(acetylacetone)trimethylenediimine, have been prepared and characterized by IR, CV and X-ray single crystal structure analyses. The ligand H2acactn is strongly metallophilic to stabilize Cu(II) ion with a square planar N2O2 coordination environment. Complex 1 can be seen as a hydrogen-bonded dimer of building block Cu(acactn) via bridging water molecules, while complex 2 is a tetrametric adduct of [Cu(acactn)] moiety and KClO4, in which K+ and ClO4− are the bridging-groups. Electrochemical studies displayed that Cu(II)/Cu(I) is an irreversible one-electron reduction process.

Chemistry of tripodal ligands. Part III.: Copper complexes of tris(benzimidazol-2-ylmethyl)amine and of its N-n-propyl derivative

Abstract The reactions of copper (I or II) salts with ligands Rntb (tris( N -alkylbenzimidazol-2-ylmethyl)amine) gave complexes [Cu(II)(ntb)Cl]Cl·3H 2 O ( 1 ), [Cu(I)(ntb)(PPh 3 )](NO 3 )·1.5H 2 O ( 2 ), [Cu(II)(Prntb)I]Cl ( 3 ) and [Cu(I)(Prntb)I] ( 4 ), depending on the reaction conditions. X-ray single crystal diffraction analyses showed the copper atom to be tetrahedrally coordinated in 2 and 4 , but square pyramidal in 1 and trigonal bipyramidal in 3 . Structural characteristics were revealed for the complexes and compared, and complex 3 was shown to be the best model compound among the four for the active center of blue copper proteins. CV studies showed the electrochemical behaviors of the complexes: 1 has two redox couples, phosphine ligation stabilizes 2 towards redox reactions, while 3 and 4 , with the same cationic formula [Cu(Prntb)I] 1+,0 have very similar complicated redox patterns, indicating the reversibility of the two species. IR and UV–Vis spectroscopic studies were also reported.

Syntheses, structures and spectroscopic properties of [Ag(dppm)(O2CCH2Ph)]2 and [Ag2(dppm)3](NO3)2·3H2O

The reaction of [Ag(dppm)(NO 3 ] 2 with sodium phenylacetate and dppm in THF at room temperature gave rise to the silver complexes [Ag(dppm)(O 2 CCH 2 Ph)] 2 ( 1 ) and [Ag 2 (dppm) 3 ](NO 3 ) 2 ( 2 ), respectively. Their crystal structures have been determined by single crystal X-ray diffraction analysis. Complex 1 is binuclear with a silver-silver separation of 3.080 A and bridged by two dppm ligands. The cation in complex 2 possesses a Ag 2 P 6 core with AgAg distance of 2.987 A and the silver atoms are each coordinated by three phosphorus atoms in an ideal trigonal-planar environment. Their IR, Raman, 1 H and 31 P NMR spectroscopic properties are also reported.

Transition metal 1,2-bidentate thiolates as building blocks and their construction into cluster complexes

Simple fragments of transition metal 1,2-bidentate thiolates, the so-called building blocks of the general compositions ML3, ML2, ML, M(O)L2, ML2L′, MLL′, etc. have been proposed to constitute the di-, tri- and tetranuclear complexes concerned in this review. Structureal regularities and characteristics have been discussed and summarized according to the thiolato ligands edt and pdt, bdt and tdt, mp, and mpo, and mpp, respectively.

Helical complexes from the self-assembly of silver salts and the polydentate thioether α,α′-bis(8-thioquinoline)-m-xylene

Abstract The self assembly of AgX with the sulfur-containing multidentate ligand α,α′-bis(8-thioquinoline)-m-xylene (m-XYTQ) affords two isomorphous complexes [Ag(m-XYTQ)]nXn (X=ClO4 1; X=BF4 2). Single crystal X-ray analyses revealed the complexes to contain linear cationic chains of [Ag(m-XYTQ)]nn+ in helical arrangement and the anions are discrete. Intramolecular π⋯π stackings pack the asymmetric units [Ag(m-XYTQ)] in shelves-like arrays while interchain π⋯π interactions between racemic chains constructed the 2D network. The key to helix formation is the folding at the sulfur sites of the spacer xylylene in the ligand. The complexes were also characterized by 1H NMR and IR.

Bivalent transition metal complexes of 4,5-diazafluorene-9-one benzoylhydrazone (HL) and the characterization of weak interaction in CoL 2 (H 2 O) 2

Abstract A new ligand 4,5-diazafluorene-9-one benzoylhydrazone (HL) and six of its transition metal complexes ML2·nH2O [ M(II) = Mn, n=2, 1; Co, 2, 2; Ni, 2, 3; Cu, 3, 4; Zn, 1.5, 5; Pb, 4, 6] have been prepared and characterized. Elemental analyses, IR, UV–Vis, 1H NMR, molar conductivity and thermal analyses measurements showed that the ligand coordinates to the metal ion with the enolic O and azomethine N atoms of the acylhydrazone group while the 4,5-diazafluorene moiety is free. Single crystal X-ray diffraction studies showed that CoL2(H2O)2, 2, has a centrosymmetric octahedral geometry of N2O4 with the two bidentate ligands in the basal plane and the two water molecules in the axial sites. The molecules of 2 are linked together by intermolecular hydrogen bonds Ndiazafluorene⋯HOH⋯N′diazafluorene and π–π stacking interactions between the diazafluorene rings to form 2D sheets.

A cleavage of the S-C bond in 2-aminothiophenal: Synthesis and crystal structure of [Ag11(μ5-S) (μ4-S2CNEt2)6 (μ3-S2CNEt2)3]

Abstract The reaction of AgNO 3 , NaS 2 CNEt 2 and H 2 NPhSH in the presence of (Ph 3 P) 3 CuCl in MeOH gave a polynuclear silver cluster compound, [Ag 11 (μ 5 -S)(μ 4 -S 2 CNEt 2 ) 6 (μ 3 -S 2 CNEt 2 ) 3 ]. A cleavage of the S-C bond and release of S 2 from 2-aminothiophenal occurred in the reaction. The core of Ag 11 S consists of five layers: Ag, 3Ag, 3AgS, 3Ag and Ag. The average Ag-Ag and Ag-S c (S c for core sulfur atom) distances are 3.046 and 2.513 , respectively. Copyright

Chemistry of aroylhydrazones II. ☆: Enol-form coordination of 4,5-diazafluorene-9-one salicyloylhydrazone (H2L) to transition metals and crystal structures of H2L, Mn(HL)2(H2O)2 and Co(HL)2(DMF)2

Abstract Transition metal complexes M(HL)2·nH2O (M(II)=Mn, n=2 (1); Co, n=3 (2); Ni, n=4 (3); Cu, n=3 (4); Zn, n=2 (5); Pb, n=0 (6)) of 4,5-diazafluorene-9-one salicyloylhydrazone (H2L), have been prepared by the reaction of H2L with the metal(II) acetates in EtOH–DMF. X-ray diffraction studies showed that the ligand in the solid state has a pseudo-helical structure in the keto-form. In complexes Mn(HL)2(H2O)2 (1) and Co(HL)2(DMF)2 (2a), the ligand coordinates to the metal ion as a mononegative ion in the enol-form with the enolic oxygen and azomethine nitrogen atoms of the aroylhydrazone group forming a five-membered chelate ring, while the phenolic hydroxyl group and pyridyl-N atoms of the diazafluorene moiety are free. The metal atoms are in octahedral geometry with N2O4 from two ligands HL in the equatorial plane and the axial sites occupied by solvent molecules. The structures were also characterized by IR and 1H NMR spectroscopy.

A tetranuclear silver complex with dppm and i-mnt ligands. Synthesis and structural characterization of [Ag4(μ-dppm)4(μ4 i-mnt)2] · 0.5 DMF (i-mnt 2,2-dicyano-1,1-ethylenedithiopate; dppm bis(diphenylphosphino)methane)

Abstract The reaction of [Ag(dppm) (NO3)]2 (1) with potassim i-mnt  2,2-dicyano-1,1-ethylenediothiolate; dppm  bis (diphenylphosphino)methane) in DMF at room temperature gave rise to the complex [Ag4(μ-dppm)4(μ4-S2C=C(CN)2)2] (2). The crystal structure of 2 has been determined by single crystal X-ray diffraction analysis. 2 is a tetranuclear complex with a silver-silver separation of 3.376(2) A and the four silver atoms form a distorted square plane bridged by four dppm and two i-mnt ligands. Each silver atom is coordinated by two phosphorus and two sulfur atoms in a distorted tetrahedral environment. The IR, 1H and 31P NMR spectroscopic properties of 2 have also been investigated.