Roussin红盐和Roussin黑盐的电子结构

Roussin黑盐簇阴离子及其"元件化合物"Roussin红盐簇阴离子,是固氮酶活性中心福州模型I(网兜状原子簇模型)的模型物.本文用闭壳层CNDO/2(S,D方案)法计算了它们的电子结构.根据计算所得的Mulliken重叠集居,电荷密度,分子轨道能量和轨道特征等数据,对成键性质进行了分析,得出如下主要结论:两种簇阴离子骨架电子的非定域性都比较强,桥硫原子Sb在由红盐形成黑盐的电子转移过程中起施主作用,两种簇阴离子中都存在M-M键,强度与M-Sb键相近,其主要贡献都来源于金属的s,pz,dz2轨道与硫原子的s,pz轨道之间的σ作用,金属d轨道的π作用对整个骨架的成键贡献很小.     

自兜反应中质子作用的量子化学模拟

本文采用CNDO/2法, 应用计算所得的键长与Mulliken键级间的关系作为判断量子化学模拟计算各化学强度的相对标准, 研究了质子环境反应物Roussin红盐的S,N,O等原子和由红盐形成Roussin黑盐的自兜反应中可能的中间状态的影响. 计算结果表明, 质子攻击可促使一个桥硫原子或一个NO基脱离体系从而有析于这一自兜反应的进行. 在反应过程中相互靠近的两个红盐阴离子之间的相互作用是影响复合体中各原子间键级变化的重要因素.     

饱和烃C-H键的活化及其配位催化反应

本文评述了饱和烃C—H键活化的最近进展,从配位催化和量子化学的观点,推断了饱和烃C—H键活化及其配位催化反应的机理:首先是它的非定域轨道里的电子对配位在催化剂中心金属的d_z~2/d_■~2-■~2混合轨道上,然后电子从催化剂的HOMO流向底物的LUMO,发生氧化加成反应,生成烷基金属氢化物过渡态,最后经插入反应、还原消除反应,完成整个催化循环。此外,还展望了未来的发展前景。     

气相色谱法研究配位化合物的热稳定性——ⅩⅢ.普鲁士蓝化合物的热分解及其加氢反应研究

普鲁士蓝化合物的热分解过程,可分为三个阶段:(1)脱水;(2)Fe³⁺还原至Fe²⁺;(3)C≡N^-键的断裂。H₂气中的热分解由于发生了一系列的加氢反应,分解产物及所对应的分解温度都不同于He气中的情况,其产物的种类增加,C≡N^-键的断裂温度降低。普鲁士蓝化合物中,CN^-呈典型的双端基配位,可看作是一种双金属配位的活化模型,与CN^-呈单端基配位的K₃[Fe(CN)₆]相比,C≡N^-键的活化程度增加,不仅断裂温度降低,且能发生更深度的加氢反应。     

气相色谱法研究配合物的热稳定性——ⅩⅣ.K_2Co[Fe(CN)_6]·H_2O和Co_3[Fe(CN)_6]_2·7H_2O的热分解及其加氢反应

K_2Co〔Fe(CN)_6〕·H_2O和Co_3〔Fe(CN)_6〕_2·7H_2O的热分解经过脱水、放出(CN)_2和HCN或C≡N~-键断裂,最终固相产物中有铁钴合金生成。CN~-的多重键在加氢时断裂,生成NH_3和CH_4。以CN~-作为加氢反应的探针,考察了C≡N~-键在金属双端基间的配位活化作用。     

盐-N,N-二甲基甲酰胺/乙醇双溶剂体系的荧光光谱分析

利用荧光光谱和量子化学计算方法研究了LiCl和MgCl2对N,N-二甲基甲酰胺(DMF)/乙醇双溶剂体系的微观结构变化的影响。通过对DMF的N—C O键以及盐与DMF和乙醇相互作用的研究发现,离子溶剂化作用导致溶剂体系结构变化,生成多种具有荧光属性的团簇,且随浓度的变化而变化。结合具有荧光属性的团簇分子跃迁能和可能的配位构型的优化以及热力学性质计算得到,共轭体系越大的团簇分子受盐的影响越小且其跃迁能越小的规律。比较Li+和Mg2+形成配位构型离子簇的稳定性和荧光强度,说明了离子极化对溶剂化的影响。     

C2v对称性簇Ru2N2的理论计算

采用密度泛函(B3LYP)方法计算了Ru2的部分低能电子组态，得到Ru2基态的电子谱项为7Δu，平衡核间距re=0.228 nm，振动频率ωe=338 cm－1，离解能De=1.92 eV. 同时计算了具有C2v对称性的Ru2N2簇中氮的活化情况，得到了各个优化几何构型下的键参数和体系能量.计算结果表明，氮氮键的活化程度由Ru2对氮起反馈作用的轨道数目决定.一般来说，氮氮键活化越强，体系能量越高，在相同的活化程度下，自旋多重度高的体系较稳定.     

面桥亚硝酰基环戊二烯基羰基铁簇合物[(η~5-C_5H_5)(μ_2-CO)Fe]_3(μ_3-NO)的合成和表征

亚硝酰基配合物中存在着线型端基(三电子基)、弯曲型端基(单电子基)、桥式和面桥式不同的亚硝酰基配位方式,这些不同配位方式在催化研究领域中的应用具有无限广阔的前景。特殊的配位方式使中心原子出现16 e结构或20 e结构,在其它配合物中只有当配体解离或缔合时才拥有这样的电子结构,因而大部分亚硝酰基配合物均具有催化活性。其次配位亚硝酰基受中心原子活化使N≡O键容易断裂,亚硝酰基被还原生成羟胺或亚胺基;活化的亚硝酰基可以作为氧源催化转化汽车废气:2NO+2CO→N_2+2CO_2或2NO+CO→N_2O+CO_2以消除污染。我们曾在室温、常压下合成亚硝酰基配合物并     

超临界二氧化碳中羰基钴催化的端基炔烃环三聚反应研究

原子经济性良好的炔烃[2+2+2]环加成反应与绿色溶剂超临界二氧化碳相结合,是一个符合绿色化学原则的环境友好反应过程.建立了一个纯超临界二氧化碳介质中八羰基二钴催化的端基炔烃环三聚反应体系,在优化的反应条件下,以较高产率选择性地制备1,2,4-三取代苯衍生物.优化了催化剂用量、二氧化碳压力、反应温度及时间等反应条件,讨论了反应物料及催化剂在超临界二氧化碳介质中的溶解性和相行为,提出了端基炔烃环三聚反应机理,并将反应底物从C≡C键拓展至C≡N键,对超临界二氧化碳介质中炔-腈环加成反应进行了初步探索.优化出的炔烃环三聚催化反应体系无需使用有机助溶剂和各类助剂,底物适应性好,产物选择性高,为合成1,2,4-三取代苯衍生物提供了一种绿色合成方法.     

双二硫代乙酰丙酮二羰基铁的合成、晶体结构和分子结构

Fe(SacSac)_2(CO)_2晶体结构已用X射线衍射法测定,对于143t个I≥3σ(I)的衍射点最后偏离因子R=0.0056,R_w=0.058。分子结构基本特征是两个二硫代乙酰丙酮基及两个羰基成顺式构型,围绕Fe原子配位的4个S原子和2个C原子基本上成八面体。分子中的两个(SacSac)-配位基均是平面状的,C-C键长与通常的取代苯C-C键十分类似,均在1.37-1.38(?)之间。     

Orthopalladation of iminophosphoranes: synthesis, structure and study of stability

The reaction of Pd(OAc)(2) with polyfunctional iminophosphoranes Ph(3)P=NCH(2)CO(2)Me (1a), Ph(3)P=NCH(2)C(O)NMe(2) (1b), Ph(3)P=NCH(2)CH(2)SMe (1c) and Ph(3)P=NCH(2)-2-NC(5)H(4) (1d), gives the orthopalladated dinuclear complex [Pd(mu-Cl){C(6)H(4)(PPh(2)=NCH(2)CO(2)Me-kappa-C,N)-2}](2) (2a) and the mononuclear derivatives [PdCl{C(6)H(4)(PPh(2)=NCH(2)CONMe(2)-kappa-C,N,O)-2}] (2b), [PdCl{C(6)H(4)(PPh(2)=NCH(2)CH(2)SMe-kappa-C,N,S)-2}] (2c) and [PdCl{C(6)H(4)(PPh(2)=NCH(2)-2-NC(5)H(4)-kappa-C,N,N)-2}] (2d). The reaction implies the activation of a C-H bond in a phenyl ring of the phosphonium group, this fact being worthy of note due to the strongly deactivating nature of the phosphonium unit. The palladacycle containing the metallated carbon atom is remarkably stable toward the coordination of incoming ligands, while that formed by the iminic N atom and another heteroatom (O, 2a and 2b; S, 2c; N, 2d) is less stable and the resulting complexes can be considered as hemilabile. The X-ray crystal structures of the cyclopalladated [Pd(mu-Cl){C(6)H(4)(PPh(2)=NCH(2)CO(2)Me-kappa-C,N)-2}](2) (2a), [PdCl{C(6)H(4)(PPh(2)=NCH(2)-2-NC(5)H(4)-kappa-C,N,N)-2}] (2d), [Pd{C(6)H(4)(PPh(2)=NCH(2)CONMe(2)-kappa-C,N,O)-2}(NCMe)](ClO(4)) (7b) and [Pd{C(6)H(4)(PPh(2)NCH(2)CONMe(2)-kappa-C,N,O)-2}(py)](ClO(4)) (3b), and the coordination compound cis-[Pd(Cl)(2)(Ph(3)P=NCH(2)CH(2)SMe-kappa-N,S)] (8) are also reported.     

陆森黑盐阴离子(Fe_4S_3(NO)_7]~-简正坐标分析

本文采用简正坐标分析法对陆森黑盐阴离子进行红外光谱的理论归属。初始力常数值取自陆森红盐。修正后的计算频率与观测频率吻合良好,平均偏差为2.6％。基于与陆森红盐力常数的对比以及与陆森黑盐晶体结构和电子结构研究结果的对比,讨论了所得力常数的合理性与可靠性。文中同时指出网兜骨架中振动模式的非定域性的特点。     

MASS SPECTRA OF ROUSSINATE ANIONS AND THEIR FRAGMENTATIONS

<正> Mass spectra of Roussinate anions in K+, Me4N+ and Bu4N+ salt have been obtained under appropriate operating conditions and the fragmentation pathways are proposed based on linked scan information of metastable transition in 1st FFR. and precise mass determinations. It was found that the skeleton structure of the red Roussinate anion is more stable than that of black Roussinate anion.It is interesting to note that rearrangement reaction with transfering of methyl radical in tetramethyl amonium to bridged sulfur atom occurs during evaporation of [(CH3)4N]2 [Fe2S2(NO)4] , forming Roussin's red methylester:In this paper we will provide some significant information in regard to the rationalization of the interconversion reaction between Roussinate anions under certain condition.     

DFT study on chemical N2 fixation by using a cubane-type RuIr3S4 cluster: energy profile for binding and reduction of N2 to ammonia via Ru-N-NHx (x = 1-3) intermediates with unique structures

The N-N bond activation of the dinitrogen ligand in the cubane-type mixed-metal sulfido cluster, [(Cp*Ir) 3{Ru(tmeda)(N 2)}(mu 3-S) 4] (tmeda = Me 2NCH 2CH 2NMe 2), is investigated by using DFT calculations at the B3LYP level of theory. The elongated N-N bond distance, red-shifted N-N stretching, and negatively charged N 2 ligand indicate that the dinitrogen is reductively activated by complexation. The degree of the N-N bond activation is classified into the "moderately activated" category, [ Studt, F. ; Tuczek, F. J. Comput. Chem. 2006, 27, 1278 ] as in the Mo-triamidoamine complex that can catalyze N 2 reduction [ Yandulov, D. V. ; Schrock, R. R. Science 2003, 301, 76 ]. Availability of the RuIr 3S 4 cluster as a catalyst for N 2 reduction is discussed by optimizing possible intermediates in a catalytic cycle analogous to that proposed by Yandulov and Schrock. A calculated energy profile of the catalytic cycle demonstrates that the RuIr 3S 4 cluster can transform dinitrogen into ammonia in the presence of lutidinium cation and Cp* 2Co as proton and electron sources, respectively. The RuIr 3S 4 clusters with an NNH x ( x = 1-3) ligand, which are intermediates in the catalytic cycle, have a significantly bent Ru-N-N linkage, although precedent NNH x complexes generally adopt a linear M-N-N array. The unique structures of the nitrogenous ligands in these intermediates are interpreted in terms of the bonding interaction between the hydrogen atom bonded to the N 2 ligand and the adjacent iridium atom in the cuboidal RuIr 3S 4 framework.     

Studies relevant to catalytic reduction of dinitrogen to ammonia by molybdenum triamidoamine complexes

In this paper we explore several issues surrounding the catalytic reduction of dinitrogen by molybdenum compounds that contain the [(HIPTNCH2CH2)3N]3- ligand (where HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3). Four additional plausible intermediates in the catalytic dinitrogen reduction have now been crystallographically characterized; they are MoN= NH (Mo = [(HIPTNCH2CH2)3N]Mo), [Mo=NNH2][BAr'4] (Ar' = 3,5-(CF3)2C6H3), [Mo=NH][BAr'4], and Mo(NH3). We also have crystallographically characterized a 2,6-lutidine complex, Mo(2,6-Lut)+, which is formed upon treatment of MoH with [2,6-LutH][B(C6F5)4]. We focus on the synthesis of compounds that have not yet been isolated, which include Mo=NNH2, Mo=NH, and Mo(NH2). Mo=NNH2, formed by reduction of [Mo=NNH2]+, has not been observed. It decomposes to give mixtures that contain two or more of the following: MoN=NH, Mo triple bond N, Mo(NH3)+, Mo(NH3), and ammonia. Mo=NH, which can be prepared by reduction of [Mo=NH]+, is stable for long periods in the presence of a small amount of CrCp*2, but in the absence of CrCp*2, and in the presence of Mo=NH+ as a catalyst, Mo=NH is slowly converted into a mixture of Mo triple bond N and Mo(NH2). Mo(NH2) can be produced independently by deprotonation of Mo(NH3)+ with LiN(SiMe3)2 in THF, but it decomposes to Mo triple bond N upon attempted isolation. Although catalytic reduction of dinitrogen could involve up to 14 intermediates in a "linear" sequence that involves addition of "external" protons and/or electrons, it seems likely now that several of these intermediates, along with ammonia and/or dihydrogen, can be produced in several reactions between intermediates that themselves behave as proton and/or electron sources.     

Cu(II)-氨基酸-核苷酸三元配合物的合成和表征

合成和表征Na~2[Cu(L-Ala)~2(5'-GMP)].2H~2O、Na~2[Cu(L-Ala)~2(5'-IMP)].6H~2O、Na~2[Cu(L-His)(5'-GMP)Cl~2^2.2H~2O和Na~2[Cu(L-His)(5'-IMP)Cl~2].H~2O四个新的三元配合物, 其中两个L-Ala分子通过羧基O和α-氨基N与Cu(II)成反式配位, 一个L-His分子通过羧基O和咪唑环上的N与Cu(II)配位; 一个5'-GMP或5'-IMP分子嘌呤环上的N(7)与Cu(II)配位; 5'-GMP的磷酸根上可能存在强氢键, 而5'-IMP的磷酸根上不存在强氢键; 在含L-Ala三元配合物中, 5'-GMP的C(6)=0可能参与配位或形成强氢键, 而5'-IMP的C(6)=0不参与配位或形成配位或形成强氢键; 在含L-His三元配合物中, 5'-IMP的C(6)=0的表现则相反。     

Formation of ammonia in the reactions of a tungsten dinitrogen with ruthenium dihydrogen complexes under mild reaction conditions

Treatment of cis-[W(N2)2(PMe2Ph)4] (5) with an equilibrium mixture of trans-[RuCl(eta 2-H2)(dppp)2]X (3) with pKa = 4.4 and [RuCl(dppp)2]X (4) [X = PF6, BF4, or OTf; dppp = 1,3-bis(diphenylphosphino)propane] containing 10 equiv of the Ru atom based on tungsten in benzene-dichloroethane at 55 degrees C for 24 h under 1 atm of H2 gave NH3 in 45-55% total yields based on tungsten, together with the formation of trans-[RuHCl(dppp)2] (6). Free NH3 in 9-16% yields was observed in the reaction mixture, and further NH3 in 36-45% yields was released after base distillation. Detailed studies on the reaction of 5 with numerous Ru(eta 2-H2) complexes showed that the yield of NH3 produced critically depended upon the pKa value of the employed Ru(eta 2-H2) complexes. When 5 was treated with 10 equiv of trans-[RuCl(eta 2-H2)(dppe)2]X (8) with pKa = 6.0 [X = PF6, BF4, or OTf; dppe = 1,2-bis(diphenylphosphino)ethane] under 1 atm of H2, NH3 was formed in higher yields (up to 79% total yield) compared with the reaction with an equilibrium mixture of 3 and 4. If the pKa value of a Ru(eta 2-H2) complex was increased up to about 10, the yield of NH3 was remarkably decreased. In these reactions, heterolytic cleavage of H2 seems to occur at the Ru center via nucleophilic attack of the coordinated N2 on the coordinated H2 where a proton (H+) is used for the protonation of the coordinated N2 and a hydride (H-) remains at the Ru atom. Treatment of 5, trans-[W(N2)2(PMePh2)4] (14), or trans-[M(N2)2(dppe)2] [M = Mo (1), W (2)] with Ru(eta 2-H2) complexes at room temperature led to isolation of intermediate hydrazido(2-) complexes such as trans-[W(OTf)(NNH2)(PMe2Ph)4]OTf (19), trans-[W(OTf)(NNH2)(PMePh2)4]OTf (20), and trans-[WX(NNH2)(dppe)2]+ [X = OTf (15), F (16)]. The molecular structure of 19 was determined by X-ray analysis. Further ruthenium-assisted protonation of hydrazido(2-) intermediates such as 19 with H2 at 55 degrees C was considered to result in the formation of NH3, concurrent with the generation of W(VI) species. All of the electrons required for the reduction of N2 are provided by the zerovalent tungsten.     

固相配位化学反应研究 XXIII: 一取代基五氰合铁(II)类配合物热分解反应的研究

本文以气相色谱法为主要手段, 配合Mossbauer谱、红外光谱等结构分析方法, 研究了一系列一取代基五氰合铁(II)类配合物Na2[Fe(CN)5L]·mH2O及Na3[Fe(CN)5L']·nH2O(L=NO^+、N2H5^+、enH^+, L'=NH3、H2O、Py)的热分解反应。结果表明所有一取代五氰合铁(II)配合物热分解过程中都形成相同的中间化合物Na4[Fe(CN)6]和Fe2[Fe(CN)6], 各配合物热分解放出取代基L(L')的温度次序与L(L')在光谱化学序列中的次序一致。本文以亚硝基铁氰化钠为代表, 详细讨论了该系列配合物的热分解反应机理以及热稳定性的规律性。     

醋酸乙烯酯基桥连铁硫配合物(σ,π-μ-CH3CO2C=CH2)(μ-RS)Fe2CO)6的制备及结构鉴定

本文报道乙酰氯同[μ-CO)(μ-RS)Fe2(CO]Et3NH相作用生成了标题化合物, 除用碳氢分析, IR, 'HNMR及X衍射技术表征这类配合物的结构和构象外, 还对形成此类产物的过程进行了初步讨论。