You Xiaozeng

Structural dependence of π–π interactions in dithiocarbazato and thiosemicarbazato nickel complexes

Structures and stabilization due to π–π interactions of N2S2 coordinated nickel(II) complexes NiL2 have been investigated by ESI-MS spectrometry and X-ray diffraction methods. For the systems with HL = 4,5-diazafluoren-9-one thiosemicarbazone (HL1), fluoren-9-one thiosemicarbazone (HL2), fluoren-9-one dithiocarbazone (HL3) and 4,5-diazafluoren-9-one dithiocarbazone (HL4), the Ni(II) atom in each complex is coordinated in a distorted square-planar geometry with two aromatic rings positioned on the same side. This cis configuration is stabilized by π–π stacking interactions between the aromatic rings. Detailed structural analyses reveal that whereas the intermolecular π–π stacking interactions connect NiL12 molecules into a one-dimensional screw chain, the intermolecular π–π stacking interactions and the C–H···π interactions link NiL22 molecules into a dimer. The π–π stacking interactions and the C–H···π interactions among the two phenyl rings and two fluorene rings of NiL32 form a closed hydrophobic brick. In NiL12 one of the two phenyl rings interacts with the two 4,5-diazafluorene rings to give an opened hydrophobic cavity; the edge-to-face interactions about another phenyl ring arrange the molecules into a one-dimensional network.

Dehydrogenation of organolanthanide alkoxides and X-ray crystal structures of the reaction product [{(C5H5)2Ln(μ-O(Me)CCHCH3)}2] (Ln Dy Yb)

Abstract Reaction Of Cp3Ln (CpC5H5; Ln  Dy, Yb) with 2-butanol in THF (THF = tetrahydrofuran) at room temperature yielded the complexes [Cp2Ln(μ-OCH(Me)CH2CH3)]2 [Ln  Dy (1, Yb (2)], which have been characterized by elemental analysis, IR and MS spectra. The complexes 1 and 2 have been dehydrogenated to give the new enolate complexes [Cp2Ln(μ-O(Me)CCHCH3)]2 [Ln  Dy (3), Yb (4)] upon refluxing in THF solution. The new complexes 3 and 4 have been structurally characterized by single-crystal diffraction studies. Complexes 3 and 4 crystallize from THF solution as isomorphous crystals of space group Pnnm with the following unit cell parameters: 3[4]; a = 9.910(5X9.853 (3)], b = 10.940(2)[10.917(3)] c = 12.258(2) [12.151(3)] A, V= 1329(1)1307(1)] A3, Z = 2, Dc = 1.82[1.90] g cm−3, R = 0.025[0.042], Rw = 0.036[0.0491. The molecules are oxygen-bridged dimers. The bridging unit Ln2O2 is completely planar. The metal atom is coordinated by two η5-Cp groups and two oxygen atoms of enolate ligands to form a pseudotetrahedral geometry. The average LnC bond lengths for 3 and 4 are 2.668(6) and 2.629(9) A, respectively. The LnC distances of 3 and 4 are 2.256(4) and 2.210(2) A, respectively. Complex 4 has been hydrolysed to give the organic compound CH3COCH2CH3, which has been confirmed by NMR spectra.

CRYSTAL STRUCTURE AND SPECTROSCOPIC STUDIES OF A NICKEL(II) COMPLEX OF A LIGAND CONTAINING NITROGEN-SULPHUR DONORS

Abstract A bis-ligand neutral Ni(II) complex of a Schiff base ligand derived from S-benzyldithiocarbazate and p-dimethylaminobenzyldehyde was prepared and characterized. Single crystal X-ray diffraction analysis of the nickel(II) chelate established that the Schiff base loses a proton from its tautomeric thiol form and coordinates to Ni(II) via the mercapto sulphur and β-nitrogen atoms. The geometry of the Ni(II) ion is square-planar with two equivalent Ni-N and Ni-S bonds; the two dimethylaminobenzyl rings and the coordinated plane are almost in one plane, forming an electronic delocalization system. When the complex crystallizes, benzene molecules are included in the crystal. However, there is no obvious interaction between the complex molecule and the benzene molecule. Magnetic and spectroscopic data support the square-planar structure found in the structure analysis. The complex crystallizes in the triclinic space group P1 with cell parameters a = 7.839(2), b = 10.528(4), c = 10.832(5) A, α = 100.61(2...

Synthesis and x-ray crystal structure of the cyclopentadienyl nitrito complex of ytterbium(III), (C5H5)2Yb(NO2) · THF

Abstract Cp 2 Yb(NO 2 ) · THF ( 1 ) (Cp = C 5 H 5 ) was synthesized by the reaction of Cp 2 YbCl and NaNO 2 (1:1 molar ratio) in THF at room temperature. It crystallizes in space group Pnma with unit cell dimensions a = 13.5530(3), b = 11.8150(2), c = 9.2790(2) A, Z = 4, V = 1485.8 A 3 and D x 1.883 g cm −3 . Least-squares refinement based on 1010 unique reflections with I ⩾ 3σ( I ) converged to a final R value of 0.023. The ytterbium atom was connected to two η 5 -bonded cyclopentadienyls and three oxygen atoms (one from the coordinated THF molecule and other two from the chelate nitrite ligands) in a distorted hexahedral arrangement. The average YbC(Cp) distance is 2.64(2) A, YbO(THF) and YbO(NO 2 ) distances are 2.310(7) and 2.388(9) A, respectively. The title complex loses the coordinated THF molecule readily on heating under vacuum to give dimeric complex [Cp 2 Yb(NO 2 )] 2 ( 2 ). Two new complexes have been characterized by elemental analysis and by IR spectroscopy and mass spectrometry.

SYNTHESIS, CRYSTAL STRUCTURE AND NONLINEAR OPTICAL PROPERTIES OF THIOSEMICARBAZONE ZINC COMPLEX

Abstract A new zinc bromide complex of a Schiff-base ligand derived from thiosemicarbazide and 4-methoxylphenyldehyde, which shows ca 13 times better SHG efficiency than urea, has been prepared and characterized. Single crystal X-ray diffraction analysis established that the coordination geometry about the zinc atom is tetrahedral with two equivalent Zn-Br and Zn-S bonds. The Schiff-base ligand is coordinated to the Zn(II) via the monodentate mercapto sulfur atom. The polar structure (space group Aba2) is stabilized by hydrogen bonds between the oxygen atom and the amino nitrogen atoms N(l). The complex crystallizes in the orthorhombic space group Aba2 with cell parameters a=11.970(2), b = 21.888(2), c= 9.157(2)A and Z = 4. The structure was solved by direct methods and refined by full-matrix least-squares to R = 0.065 and R w = 0.117 for the 722 observed reflections with I > 2[sgrave](I).

Synthesis, crystal structure and photochromism of tri(N,N,N′,N′-tetramethylethylendiammonium)heptamolybdate(VI)tetrahydrate

Abstract The reaction of MoO 3 with the organic donor N , N , N ′, N ′-tetramethylethylenediamine (TEMED) in aqueous solution yielded a photosensitive compound [C 6 H 18 N 2 ] 3 [Mo 7 O 24 ]·4H 2 O, tri( N , N , N ′, N ′-tetramethylethylenediammonium)heptamolybdate(VI)tetrahydrate. The crystal structure was determined by X-ray analysis. Seven MoO 6 distorted octahedra share edges which have four ranges of MoO bond distances. The heptamolybdate anion of the crystal has approximate mm 2 symmetry and its structure is similar to that observed in the crystals of other heptamolybdate salts. The N , N , N ′, N ′-tetramethylethylenediammonium cations and crystal water form two different hydrogen bonds to the bridging and terminal oxygens of the heptamolybdate: O⋯Ow 2.80(1) A and O⋯N 2.618(8)–3.09(1) A. These hydrogen bonds play an important role in the photosensitivity of the crystals. XPS data indicate that the bonding energies of oxygen and molybdenum of the title compound are decreased after it was irradiated with UV light.

Synthesis and characterization of ferrocene-containing new schiff base complexes. The X-ray crystal structure of (C10H6N2)CNNCHFc

Abstract A series of novel ferrocene-containing Schiff base complexes, (C10H6N2)CNNCRFc, (C10H6N2)CNC6H4NCRFc and (C10H6N2)CNC6H4C6 H4NCRFc (R: H, CH3), have been synthesized using 1,10-phenanthroline and ferrocene as starting materials. The derivatives were characterized by elemental analyses and spectral data (IR, UV, MS and 1H NMR). The single-crystal X-ray structure is presented for (C10H6N2)CNNCHFc (1). The cyclic voltammograms of complex 1 have shown reversible one-electron oxidation and two-step one-electron reduction.

CRYSTAL STRUCTURE AND PHOTOCHEMISTRY OF BIS(BIPYRIDINE)-BIS(4-AMINOPYRIDINE)RUTHENIUM(II)

Abstract The title complex, cis-[Ru(bpy)2(4-apy)2] (ClO4)2CH3CN (where bpy = 2,2′-bipyridine, 4-apy = 4-aminopyridine), has been synthesized and characterized. An X-ray crystal structure determination established that the coordination geometry about ruthenium(II) is distorted octahedral with four nitrogen atoms from the two bpy molecules and two pyridine nitrogen atoms from apy coordinate. Time-resolved and steady-state luminescence spectra show that the emission wavelength, quantum yield and the luminescence lifetime are quite similar to those of corresponding complexes with pyridine instead of apy, which indicates that the amino group of the apy cannot quench the luminescence. Electrochemistry in CH3CN is consistent with this result. The complex crystallines in the monoclinic space group, P21/n with cell parameters a = 10.585(2), b = 11.615(2), c = 15.992(3) A, β = 99.76(3)° and Z = 4. The structure was refined by full-matrix least-squares methods to R = 0.071 and Rw = 0.093 for 4625 reflections having ...

Theoretical calculations of95Mo-NMR chemical shifts for compounds [MoO4−nS n ]2−

SummaryTheoretical calculation of95Mo-NMR chemical shifts for [MoO4−nSn]2− (n=0−4) compounds is reported here for the first time on the basis of Fenske-Hall method and Sum-Over-State (SOS) perturbation theory. A systematic decrease in shielding of95Mo nuclei with increase of number of sulfur in [MoO4−nSn]2−, which is observed experimentally, can be reasonably explained by our calculation. A good linear relationship between chemical shifts of calculation and experiment is obtained. The electronic structure and bonding in these compounds are also discussed.

Synthesis and Characterization of Biferrocene Schiff Base Complexes

Abstract A series of mono- or di- substituted biferrocene-containing Schiff base complexes Fc-X-Fc and Fc-X2-Fc (X=-CH=N-C6H4-N=CH-, -CH=N-C6H4-C6H4-N-=CH- and -CH=N-C6H4-CH2-C6H4-N=CH-) have been synthesized by means of condensation of formylferrocenes with amines under improved conditions. The complexes were characterised on the basis of their elemental analyses and spectral data (IR, UV, 1H NMR, magnetic moment and MS). The complexes are oxidized by iodine in absolute ethanol to give mixed valence compounds, which showed paramagnetic properties.