Yu Kaibei

Synthesis, structure and properties of an imidazolate bridged copper, zinc binuclear complex:A model compound for Cu,Zn-SOD

Abstract A new imidazolate bridged Cu 2+ , Zn 2+ binuclear complex [(dtma) CuImZn (dtma)]ClO 4 · 2.5H 2 O taken as an active site model for Cu,Zn-SOD has been synthesized and its crystal structure has been determined. All the bond lengths, bond angles and the distance between copper and zinc atoms in the CuImZn core of the model complex are close to those in Cu,Zn-SOD. ESR parameters of the model complex as a function of pH show that the imidazolate bridge is stable in the pH range 10–12, and is broken on the zinc side at pH ∼ 9. With decreasing pH, the imidazole is released at pH ∼ 4 and the dtma ligand dissociates from the copper-containing fragment at pH ∼ 2.4.

Synthesis and structural characterization of two novel heteronuclear cluster compounds, [NEt4]4[WS4Cu5Br7] and

Abstract The title compounds have been obtained by the reaction of [NH 4 ] 2 (WS 4 , CuBr, [NEt 4 ] 4 Br and [Bu n 4 N]Br in the solid state ( 1 ), or by the reaction of [NH 4 ] 2 [WS 4 ], CuI and [Bu n 4 N]I in the solid state and the pyridine substitution of the solid-state product in acetonitrile ( 2 ). X-ray diffraction analysis confirms that in the structure of 1 five of the six edges of the [WS 4 ] 2− tetrahedron are coordinated by CuBr units forming an open, double cubane-like structure, which possesses crystallographically imposed C 2 symmetry. The structure of 2 , which possesses a crystallographic 4 symmetry axis situated at the tungsten atom, consists of a tetrahedral WS 4 core enveloped by an octahedral array of six copper atoms, forming a WS 4 Cu 6 aggregate. Linked by Cu eq ICu eq  bridges, this aggregate connects with its nearest neighbours and develops a two-dimensional network. The substitution reactions of the solid-state product with pyridine are discussed.

The structure and magnetic properties of μ3-oxotriiron(III) complex [Fe3O(OBZ)6(CH3OH)3] (NO3)(CH3OH)2 (HOBZ = benzoic acid)

Abstract A new μ3-O triiron(III) complex [Fe3O(OBZ)6(CH3OH)3](NO3)(CH3OH)2 (HOBZ = benzoic acid) has been synthesized, its structure has been determined and variable temperature magnetic susceptibility has been measured. In the cation of the complex, three iron atoms form an equilateral triangle with μ3-O in the centre. An intramolecular antiferromagnetic exchange interaction occurs with J = −27.06 cm−1, and a weaker intermolecular antiferromagnetic exchange interaction occurs with zJ′ = −2.59 cm−1.

Crystal structure and characterization of Rb2Ca[B4O5(OH)4]2·8H2O

Abstract Dirubidium calcium tetraborate octahydrate, Rb 2 Ca[B 4 O 5 (OH) 4 ] 2 ·8H 2 O, was prepared by reaction of Rb-borate aqueous solution with CaCl 2 and its structure has been determined by single-crystal X-ray diffraction data. It crystallizes in the orthorhombic system, space group P 2 1 2 1 2 1 with unit cell parameters, a=11.536(2) A , b=12.639(2) A , c=16.690(4) A ; Z =4, V=2433.5(8) A 3 . The structure contains alternate layers of [B 4 O 5 (OH) 4 ] 2− polyanions separated by water molecules and Rb, Ca cations. The isolated [B 4 O 5 (OH) 4 ] 2− is constructed from two BO 3 (OH) tetrahedron groups and two BO 2 (OH) triangular groups joined at common oxygen atoms. The two BO 3 (OH) tetrahedron groups are further linked by means of an oxygen bridge across the ring. The Ca 2+ ion displays seven coordination, while the two non-equivalent Rb + ions display nine and seven coordination, respectively. Infrared and Raman (4000–400 cm −1 ) spectra of Rb 2 Ca[B 4 O 5 (OH) 4 ] 2 ·8H 2 O were recorded at room temperature and analyzed. Fundamental vibrational modes were identified and band assignments were made. The dehydration of this hydrated mixed borate occurs in one step and leads to an amorphous phase which undergoes a crystallization.

Structure and magnetic exchange of an imidazolate-bridged copper dimer: [(dtma)Cu(im)Cu(dtma)]ClO4·2.5H2O

Abstract The compound of the formula [(dtma)Cu(im)Cu(dtma)]ClO4·2.5H2O (where dtmaH is 4-diethylenetriamineacetic acid and im is the imidazole anion) was synthesized and its crystal structure determined by X-ray diffraction methods. The structure consists of a dimeric complex bridged by the deprotonated imidazole. The geometries of the coordination polyhedron around the copper(II) ions are very near to tetragonal pyramid. The X-band ESR powder spectrum shows broad ΔM = 1 and weak ΔM = 2 absorptions. Variable-temperature (4.2–300 K) magnetic susceptibility data gave the antiferromagnetic interaction parameters J = −37 cm−1. This behaviour is best accounted for by a superexchange mechanism involving σ- and π-exchange pathways.

Crystal structure and thermal behavior of Rb2Co[B6O7(OH)6]2·4H2O

Abstract A crystal of the complex borate Rb 2 Co[B 6 O 7 (OH) 6 ] 2 ·4H 2 O was synthesized in the molar ratio Rb 2 O/CoCl 2 /B 2 O 3 =4:1:9, and its structure was determined by single-crystal X-ray diffraction. It belongs to the P 1 triclinic space group, with the following unit cell parameters: a =7.549(1) A, b =7.872(1) A, c =10.980(2) A, α =107.87(1)°, β =94.83(1)°, γ =90.27(1)°, Z =2, V =618.45(19) A 3 . The crystal structure was solved from 2162 independent reflections until R =0.0127. The crystal structure of Rb 2 Co[B 6 O 7 (OH) 6 ] 2 ·4H 2 O consists of [B 6 O 7 (OH) 6 ] 2− polyborate anions, Co–O octahedra and Rb–O polyhedra. The isolated [B 6 O 7 (OH) 6 ] 2− polyborate anions are separated by free water molecules and Rb and Co cations. Dehydration of this hydrated mixed borate occurs in two steps and leads to an amorphous phase which undergoes crystallization.

Reaction of sulfur-containing structural units of transition metals

Two tri-n-butylphosphine-participated (PBu 3 n ) nickel (II) complexes of 2-mercaptophenol (H2mp), i.e. Ni2Ru(mp)3(Hmp)(PBu 3 n )3 3 exhibiting a curved heterotrinuclear metal skeleton and its mononuclear “synthon”, [HNEt3 ] [ Ni(mp) (Hmp) (PBu 3 n )] 1 were synthesized and characterized by X-crystallography and1H NMR, FAB-MS and cyclic valtammogram measurements. The nickel (II) center in 1 has a square-planar geometry. For 3, the ruthenium (III) atom is in a distorted octahedral environment and the two nickel (II) atoms exhibit squareplanar and rare triangle-planar geometries, respectively. The Ni (1) -Ru-Ni(2) arrangement is severely asymmetric with the distances 0.254 and0.394 nm, respectively, for Ni(1)-Ru and Ni(2)-Ru. The structural regularities of relevant complexes are summarized in relation to the structural as well as spectra data.

Preparation and Structure Characterization of 4-Amino-1,2,4-triazol-5-one Hydrate

Abstract4-Amino-1,2,4-triazol-5-one hydrate (ATO·H2O) was prepared and its structure was analyzed by four-circle diffraction measurement. The obtained results show that the crystal belongs to the triclinic crystal system, space group P 1 with crystal parameters a = 6.432(1), b = 6.551(1), c = 6.740(1) Å; α= 68.04(1), β = 82.18(1), γ = 81.90(1)°, V = 259.7(7) Å3; Z = 2; Dc = 1.510 g/cm3; μ = 0.131 mm-1; F(000) = 124. ATO·H2O was characterized by FT-IR analysis, X-ray diffraction analysis, and single crystal diffraction analysis.

Synthesis and Characterization of Nitro-p-xylenes

In this paper we elected to nitrate p-xylene because this compound has only one mononitro- and trinitro- isomer. Trinitro-p-xylene was used as a starting material for the synthesis of other compounds in subsequent work. The mononitration of p-xylene can be easily carried out at 30°C. Nitro-p-xylene is easily nitrated to dinitro-p-xylene at a temperature of 80°C. The trinitro-p-xylene can be obtained at 120°C. Single crystals of 2,3-dinitro-p-xylene and 2,3,5-trinitro-p-xylene were grown using the slow cooling method and we report the X-ray structure of the former. The thermal decomposition of the compounds was studied using differential scanning calorimetry (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) techniques and FT-IR. The target compounds were also characterized by 1H-NMR, 13C-NMR and MS.

Synthesis and reactions of new type carbyne compounds; crystal structure of the compounds [Br(CO)2(C5H5N)2MoCC6H5]

Abstract The compound [Br(CO)4Mo(CC6H5)] reacted with pyridine in dichloromethane to give the pyridine-substituted molybdenumcarbyne compound [Mo(CC6H5) Br(CO)2(Py)2] (1), the structure of which was established by a single-crystal X-ray diffraction study. The molecular possesses mirror symmetry, defined by the atoms Br, Mo, C(2) and C(3). Compound 1 reacted with α,α′-dipyridine and Ph2PCH2CH2PPh2 (dppe) giving the carbyne compounds [Br(CO)2(bipy)Mo(CC6H5)] (2) and [Br(CO)2(dppe) Mo(CC6H5)] (3), respectively. From the reaction of 1 and 2 with [S2Fe2(CO)6]2− compounds, [L(CO)2(C6H5C)MoSFe2(CO)6SMo(CC6H5) (CO)2L] [(4 L = (Py)2; (5) L = bipy] were obtained. The structures of these new type carbyne compounds are suggested.