Synthesis, Crystal Structure, UV-vis and EPR Studies of（ NH3CH2CH2NH2 ） 2.5 [ Mo0.5^（V）W0.5^（VI）O2 （ OC6H4O ） 2]

Cis-dioxo-metal complex ( NH3CH2CH2NH2 ) 2.5 [ Mo0.5^(V)W0.5^(VI)O2 ( OC6H4O ) 2] 1 was obtained by the reaction of tetra-butyl ammonium hexamolybdotungstate with 1, 2-dihydroxybenzene in the mixed solvent of CH3OH, CH3CN and ethylenediamine,and characterized by X-ray diffraction, UV-vis and EPR analysis. Compared with its analogous complexes (NH3CH2CH2NH2)3[Mo^(V)O2(OC6H40)2] 2 and (NH3CH2CH2NH2)2[W^(VI)O2(OC6H4O)2] 3, the results show that tungsten(VI) is less active in redox than molybdenum (VI) and that the change of the valence induced by substitution of W(VI) for Mo(V) in EMO2(OC6H40)2]n- does not influence the coordination geometry of the complex anion in which the metal center exhibits distorted octahedral coordination with cis-dioxo catechol. The responses to EPR of complexes 1 and 2 are active but complex 3 is silent,and the UV-vis spectra exhibited by the three complexes are obvious different because of the different electronic configuration between the central Mo(V) and W(VI) ions in the complexes.It is noteworthy that complexes 1 and 2 have the similar EPR signal to flavoenzyme, suggesting that the three complexes have the same coordination geometry feature with the co-factor of flavoenzyme.     

{Na2[μ2-(C6H4O2)2](C6H4OOH)2}4-的结构及其在固态合溶液中的NMR比较

The new compound （NH3CH2CH2NH3）2{Na2[μ2-（C6H4O2）2]（C6H4OOH）2} has been synthesized and characterized by elemental analysis, IR, UV, NMR and single crystal X-ray diffraction. The yellow crystals crystallized in the triclinic system with space group P-1 and a=0.6091（2） nm, b= 1.0274（3） nm, c= 1.2466（4） nm, α=89.073（6）°, β=89.376（6）°, γ=78.873（5）°, V=0.7653（4） nm^3, Z= 1, R1=0.0568, wR2=0.1198. Every sodium ion coordinates in trigonal prismatic fashion with two O atoms from a terminal chelating catecholato ligand and four O atoms from bridging P2 catecholato ligands, Two neighboring NaO6 trigonal prisms are face-shared and centrosymmetric with regard to the inversion center consisting of four tri-bridging O atoms to form a binuclear cluster {Na2[μ2-（C6H4O2）2]}^2- anion. The comparison of ^13C NMR spectrum of tlie complex in solid state with that in solution indicated that the rapid exchange between the bridging [μ2-（C6H4O2]^2- and terminal [C6H4OOH]^- ligands was present in solution.     

(NH_2CH_2CH_2NH_3)_4[W~ⅤO_2(OC_6H_4O)_2]_2(NH_3CH_2CH_2NH_3)·H_2O的合成、晶体结构、EPR以及与同构物的比较

在很多生物代谢过程中,微量元素W起着关键作用,W与生物大分子结合形成具有特异功能的钨氧转移酶。1983年从热醋酸菌中提取了第一种钨酶,即甲酸脱氢酶,目前从生物体内提取的钨酶种类已达十二种之多,并发现钨氧转移酶与钼氧转移酶的活性结构因子呈相近性[1]。随着钨酶在生物体内的作用逐步得到重视,及其模拟的功能配合物在探究钨酶的生理活性和催化机理研究中所作的突出贡献,使钨氧转移酶活性结构因子的仿生合成、生理活性以及催化机理研究成为研究热点[2￣14]。根据报道显示,单分子的钨氧模拟配合物中W的价态只有WⅣ、WⅥ两种,且形成一个电…     

(NH3CH2CHNH2CH3)2[WVIO2(OC6H4O)2]的合成、晶体结构及其与ATP相互作用的NMR性质研究

在室温下, 选用具有手性特征的1,2-丙二胺(1,2-propanediamine)为对阳离子, 由正四丁基铵十钨酸盐和邻苯二酚反应, 得到了钨酶活性结构因子仿生配合物(NH3CH2CHNH2CH3)2[WVIO2(OC6H4O)2], 用单晶X射线衍射测定了其晶体结构, 晶体属单斜晶系, 空间群为P21/n, a＝1.1099(3) nm, b＝1.0416(3) nm, c＝1.8874(6) nm, β＝96.492(6)°, V＝2.1679(11) nm3, z＝4, R1＝0.0445, wR2＝0.0682; 并对它进行了IR, 1H NMR和UV-Vis谱学表征. 利用NMR研究了其与三磷酸腺苷(ATP)的相互作用, 结果发现手性特征的1,2-丙二胺及邻苯二酚苯环的1H化学位移在与ATP混合前后均呈现出较大的差异, 分析得出: 配合物中的金属离子在D2O中大多数均以W(V)价态存在, 但在与ATP共存时转化为W(VI), 并与配体发生了解离.     

[(NH2CH2CH2NH3)2WⅥO2(NHC6H4NH)2]2(NH2CH2CH2NH2)·H2O配合物的合成与晶体结构

Cis-dioxo-tungsten(Ⅵ) complex, (NH₂CH₂CH₂NH₂)[(NH₂CH₂CH₂NH₃)₂W^ⅥO₂(NHC₆H₄NH)₂]₂·H₂O is synthesized at room temperature by the reaction of sodium tungstate with o-phenylenediamine. The crystal structure of complex was determined by X-ray diffraction structural analysis. The results show that complex belongs to monoclinic system with space group P2₁/ c, a=0.712 8(2) nm, b=3.081 1(10) nm, c=0.981 9(3) nm, β=102.615(4)°, V=2.104 4(11) nm³, Z=2, μ=55.26 cm^-1, F(000)=1 176. Compared the complex with its analogous biomimetic complexes of the cofactor of molybdoenzymes and tungstoenzymses, it is found that the variance of the coordination atoms and the metal ions center have no influence on the coordination feature, and exhibits distored octahedral coordination with cis-dioxo o-phenylenediamine. CCDC: 252834.     

钨酶的研究进展

钨酶是近年来才发现的存在于生物体内具有特殊生化活性的重要物质.本文主要介绍钨酶的类型、钨酶活性端的结构以及钨酶的光谱性质,并对钨酶的近期研究进展进行综述.     

(NH2CH2CH2NH3)4[WⅤO2(OC6H4O)2]2(NH3CH2CH2NH3)·H2O的合成、晶体结构、EPR以及与同构物的比较

Cis-dioxo-catecholatotungsten(Ⅴ) complex (NH₂CH₂CH₂NH₃)₄[W^ⅤO₂(OC₆H₄O)₂]₂(NH₃CH₂CH₂NH₃)·H₂O (1) was synthesized at room temperature by the reaction of tetrabutyl ammonium decatungstate with catechol in the mixed solvent of CH₃OH, CH₃CN and NH₂CH₂CH₂NH₂. The crystal structure of complex was determined by X-ray diffraction structural analysis. The results show that complex belongs to monoclinic system with space group P2₁/c,a=0.712 8(3) nm, b=3.082 3(11) nm, c=0.982 8(4) nm, β=102.639(6)°, V=2.106 8(14) nm³, Z=2, R₁=0.062 8, wR₂=0.183 7. Compared the complex with its analogous complexes (NH₂CH₂CH₂NH₃)₃[Mo^ⅤO₂(OC₆H₄O)₂], it is found that the coordination structure of W have no changes in the processing of electron transfer of tungsten-containing enzymes from the result of the similarity of the EPR spectra of the complexes and flavoenzyme from milk. CCDC: 272937.