Dai Anbang

Synthesis, properties and X-ray crystal structure of a bicopper(II) complex of N,N',N,N'- tetra(2-aminoethyl)-1,1,2,2-ethanetetraamide

Abstract We have synthesized a bicopper(II) complex of N,N′,N″,N‴-tetra(2-aminoethyl)-1,1,2,2-ethanetetraamide and determined its crystal structure by X-ray diffraction. The complex has two dioxotetraamine sub-units linked by a CC bond. Each copper is situated in a square-pyramid consisting of four nitrogen atoms and one water molecule. The nitrogen atoms of the amido groups have stronger coordination ability than those of amino groups because of their deprotonation. The complex binds 10 water molecules and forms 22 hydrogen bonds. The large network of hydrogen bonds stabilizes the crystal. The complex has an EPR spectrum both in the solid and in frozen aqueous solution corresponding to mononuclear copper(II). Each copper has a magnetic moment of 1.74 μB. It has two redox processes at 0.62 and 0.79 V (vs SCE), respectively. IR, TG and conproportionation constants were also discussed.

Solid state reactions of coordination compounds by gas chromatography

Here we report a review of the results of our studies in recent years on reactions of coordination compounds in solid state at ordinary ard medium temperatures. The studies have been made mainly by means of gas chromatography coupled with various spectroscopic methods. The results are described with respect to the following aspects:

Thermal decomposition of K3Co(CN)5L in hydrogen atmosphere and the influence of reduced iron powder

Abstract The thermal decomposition of K 3 Co(CN) 5 L (L = CN − , NO 2 − , N 3 − , NO) in a hydrogen atmosphere has been studied by gas chromatography. The first stage of thermal decomposition of these complexes is to release crystal water if contained, and the second stage is to dissociate the ligand at very high speed, with a large amount of heat being released when LN 3 − . Thirdly, the residual cyano-cobalt complex is further decomposed to form HCN, (CN) 2 and N 2 and a little NH 3 and CH 4 . In the presence of iron powder, the evolution of NH 3 is increased greatly, whereas HCN disappeared entirely. The influence of reduced iron powder upon the decomposition is also studied.

Studies on solid state redox reaction of iron(III) oxalate by gas chromatography

Abstract The solid state redox reaction of iron (III) oxalate with sodium nitrate and tin(II) chloride was investigated in hydrogen atmosphere and helium atmosphere by use of a non-isothermal technique. The evolved gases (EG) formed during the reaction were directly detected by gas chromatography, and the solid products were also identified by XRD, Mossbauer spectra and IR. The results show that the solid state redox reaction can go to completion because electron transfer is much easier than mass diffusion along the boundaries of the reactant. The releasing of crystal and coordination water during the redox reaction also facilitates completion of the reaction. The mechanism of the solid state reaction is also discussed.

Synthesis, Crystal Structure, and Properties of [Cu(tren)(im)Zn(tren)](ClO 4 ) 3 ·CH 3 OH as a Model Compound of BESOD

This paper reports the synthesis,properties and crystal structure of the title model compound with the ESR parameters g_∥ =2.007,g_⊥=2.191, A_∥=0.0061 cm~(-1), and A_⊥=0.0114 cm~(-1). The crystal belongs to space group C_2~2-P2_1,a=8.924(2),b=11.590(4), c=16.356(6),β =91.40(2)°,Z=2.Cu(Ⅱ) and Zn(Ⅱ) are bridged by the imidazolate ring, with the distance of 5.84.The conductivity and electronic reflectance spectrum of the complex are described.pH dependence in an aqueous solution is also investigated by potentiometric titration, and fitted by a self-written computer program. The results indicate that the imidazolate bridge splits at the side facing Zn(Ⅱ) below pH 8.

STUDIES ON STRUCTURES OF SOME PLATINUM COMPLEXES WITH 1, 1-CYCLOPROPANEDICAR BOXYLATE

The crystal structures of [Pt(NH3)2CPrDCA].H2O (I), [Pt(CH3NH2)2CPrDCA] (II), and [Pt(dmbn) CPrDCA].2.5H2O (III) (where CPrDCA is 1,1-cyclopropanedicarboxylate; dmbn is 2,3-dimethyl-2,3-butyldiamine) are determined. Compound I crystallizes in the orthorhombic space group Pnma with the cell dimensions: a = 6.517(2), b = 9.709(3), c = 14.205(5) A, Z = 4, R = 0.058. Compound II is monoclinic with space group P2(1)/n, a = 9.648(3), b = 8.720(2), c = 12.770(4) A, beta = 107.12(2), Z = 4, R = 0.059. Compound III belongs to the monoclinic system space group P2(1)/m with the cell dimensions: a = 6.494(1), b = 19.638(3), c = 6.606(1)A, beta = 94.44(1), Z = 2, R = 0.038. Electronic structures of the complexes are studied and the correlation between structure of the amine ligands and biological activity of the complexes is explored.

A MODEL STUDY ON MODE OF BONDING OF CISPLATIN WITH DNA

The interaction of cis-[Pt(NK_3)_2Cl_2] with nucleosides, as constituents of DNA, was studled by spectrophotometric, ~(13)C NMR and CNDO/2 methods. The apparent stability constants of the complexes formed and the initial rate of formation were determined. The sites of binding of nucleoside (or nucleotide) with Cisplatin were ascertained and the electronic structure of the model coordination compounds of Cisplatin and guanine was calculated by MO approach. On the basis of the obtained results, the mechanism of the antitumour action of Cisplatin was discussed, and a new possible mode of bonding of Cisplatin with DNA was proposed.

THE STATE OF CHROMIUM (III) ION IN AQUEOUS SOLUTION

So far few systematic studies on the hydrolytic polymerization of Cr(Ⅲ) were reported because of inertness of the ion and complication of the process. We studied it in equilibrium by pH method systematically in a wide concentration range (0.0002—0.32 M). The results show that, in the low concentration range, the composition of the polynuclear hydrolysis products may be represented as [Cr_3(OH)_4] (OH)_n (n=1,2,3); in the medium range, the composition of products as Cr[Cr(OH)_2]_n~((3+n))~+ (n=1,2,3); in the high range, the composition of products as Cr[Gr(OH)]_n~((3+2n))~+ (n=1, 2), and in the intermediate range between medium and high range where the hydrolysis system is in a transition state, the composition of products as [Cr_3(OH)_3]~(6+) and [Cr_3(OH)_4]~(5+). The values of hydrolysis constants of the identical species measured in different Cr concentration ranges and calculated by different methods were found in good agreement with each other. A predominance-arca diagram was made by using the hydrolysis constants obtained.