异三核过渡金属配合物[F32^ⅢMⅡO（OOCC2H5）6L3]M=Co,Ni,Mn;L=C5H …

在合成和表征了一系列新的异核异价三核过渡金属羰酸配合物〖Ｆｅ２＾ⅢＭⅡＯ（ＯＯＣＣＨ２Ｈ５）６Ｌ３〗（Ｍ＝Ｃｏ,Ｎｉ,Ｍｎ,Ｌ＝Ｃ５Ｈ５Ｎ,Ｈ２Ｏ）的基础上,利用多种ＮＭＲ技术并结合ＵＶ研究了这些配合物在不同溶剂介质和温度下的谱学特征和动力学性质。利用谱峰积分比例、线宽、相同骨架分子的配体取代和纵向驰豫时间对＾１ＨＮＭＲ谱进行了归属。实验结果表明：这类配合物的金属离子间宫心桥存在一定的反铁磁作用,     

三核过渡金属配合物[M3ⅢO(OOCR)6L3]+(M=Cr,Fe,Mn;R=CH3,C2H5,CH2NH2;L=C5H5N,H2O)的1H NMR性质

采用1H NMR谱研究了通式为[M3ⅢO(OOCR)6L3]+(M=Cr,Fe,Mn;R=CH3,C2H5,CH2NH2;L=C5H5N,H2O)的一系列氧心三核过渡金属配合物,主要考察其1H化学位移随金属、配体、温度、溶剂等因素变化而变化的规律.结果表明,骨架金属对化学位移的影响最大,M3O中的3个金属离子间存在反铁磁交换相互作用.对Mn配合物中顺磁中心对化学位移和线宽的影响机制的研究表明,其1H各向同性位移主要由接触作用贡献.     

异三核过渡金属配合物[Fe2ⅢMⅡ O(OOCC2H5)6L3](M=Co,Ni,Mn;L=C5H5N,H2O)溶液行为的NMR和UV谱表征

在合成和表征了一系列新的异核异价三核过渡金属羧酸配合物[Fe2IMIO)-(OOCC2H5)6L3](M=Co,Ni,Mn;L=C5H5N,H2O)的基础上,利用多种NMR技术并结合UV谱研究了这些配合物在不同溶剂介质和温度下的谱学特征和动力学性质.利用谱峰积分比例、线宽、相同骨架分子的配体取代和纵向弛豫时间对1H NMR谱进行了归属.实验结果表明:这类配合物的金属离子间通过中心氧桥存在一定的反铁磁相互作用,从而在整体上削弱了顺磁性的影响,仍能观察到NMR谱.实验还发现这些配合物在CD3CN和DMSO)溶剂中的结构与晶体结构一致,而在水中则分解为金属离子、羧酸盐和吡啶.这些结果有助于指导类似配合物的合成.     

三核过渡金属配合物[M3^ⅢO（OOCR）6L3]^＋（M=Cr,Fe,Mn;R=CH3,C2H5,CH …

采用＾１Ｈ ＮＭＲ谱研究了通式为（Ｍ３＾ⅢＯ（ＯＯＣＲ）６Ｌ３）＾＋（Ｍ＝Ｃｒ,Ｆｅ,Ｍｎ;Ｒ＝ＣＨ３,Ｃ２Ｈ５,ＣＨ２ＮＨ２;Ｌ＝Ｃ５Ｈ５Ｎ,Ｈ２Ｏ）的一系列氧心三核过渡金属配合物,主要考察其＾１Ｈ化学位移随金属、配体、温度、溶剂等因素变化而变化的规律。结果表明,骨架金属对化学位移的影响最大,Ｍ３Ｏ中的３个金属离子间存在反铁磁变换相互作用。对Ｍｎ配合物中顺磁中心对化学位移和线宽的影响机制的研究表     

氧心羧桥异三核过渡金属簇合物[Fe2MO(CH3COO)6Py3].Py(1,M=Mn;2,M=Co;3,M=Ni)和[Fe2MO(CCl3COO)6(THF)3](4,M=Mn;5,M=Co;6,M=Ni)电子光谱的研究

The UV/VIS spectra for pyridine solution of complexes [Fe_2MO(CH_3COO)_6Py_2]·Py and THF solution of complexes Fe_2MO(CCl_3COO)_6(THF)_3 were studied. The d-d transitions were assigned and the ligand field parameters(B,D_q,β) were calculated for the related metal ions according to ligand field theory (Tanabe-Sugano diagram) in terms of O_h symmetry and reasonably good fits were obtained for the calculated and observed frequencies. The calculated results show that (1) the larger the ionic potential for M~(2+) ion, the larger the values of B, D_q for Fe~(3+) ion (2) the ligand field parameters of metal ions vary in parallel with the electronagativity of R in RCOO~-.     

氧心羧桥异三核过渡金属簇合物[Fe_2MO(CH_3COO)_6Py_3]·Py(1,M=Mn;2,M=Co;3,M=Ni)和[Fe_2MO(CCl_3COO)_6(THF)_3](4,M=Mn;5,M=Co;6,M=Ni)电子光谱的研究

氧心羧桥三核物通式为[M_3O(RCOO)_6L_3]~(n+)(n=1,0)虽然它在三十年代就已合成出来,但是引起人们广泛兴趣的还是近年来发现的它所具有的特殊稳定性和不寻常的物理化学性质。我们测定了不同M~(2+)离子,两种羧桥的铁系列异三核标题簇合物的晶体结构和有关物理性质。该类型化合物的结构可以看成由共享μ_3-O顶点的三个金属离子的配位八面体组     

(1,3,5-C3P3H3)M与(1,3,5-C3P3H3)2M (M=Ti,V, Cr)配合物的结构与芳香性

运用密度泛函理论研究了(1,3,5-C3P3H3)M和(1,3,5-C3P3H3)2M (M=Ti,V,Cr)的结构、键合能以及芳香性.结果表明:低自旋的(1,3,5-C3P3H3)M和(1,3,5-C3P3H3)2M基态结构分别具有C3v和D3h对称性.金属与配体间为共价作用,二者之间存在σ、π和σ三种成键方式.V的三明治配合物的解离方式与Ti和Cr的三明治配合物不同,前者为分步解离,后两者则为一步解离.其中(1,3,5-C3P3H3)2Cr(D3h)的第一解离能最大,配合物最稳定.这些三明治和半三明治配合物都具有中心芳香性、内芳香性和外芳香性,且中心芳香性均大于自由配体(1,3,5-C3P3H3)的中心芳香性,芳香性主要贡献来源于π键和金属原子的孤对电子.内芳香性按照Ti、V、Cr的顺序依次增大,且内芳香性明显要大于外芳香性.高自旋的半三明治(1,3,5-C3P3H3)Ti(C3,5A1)与单重态(1,3,5-C3P3H3)Ti (C3v,1A1)相比,配体的变形性增大,稳定性增加,且C平面中心芳香性和内芳香性均增大,但P平面的中心芳香性却降低.     

纳米晶室温分子磁体K0.45VⅡ1.12VⅢ0.19[Cr(CN)6](SO4)0.13·4.34H2O--亚铁磁长程有序与自旋玻璃态共存

用VSO4·2.5H2O与K3[Cr(CN)6]·2.5H2O反应,合成了一个结晶的普鲁士蓝类室温分子磁体K0.45VⅡ1.12VⅢ0.19[Cr(CN)6](SO4)0 13·4.34H2O,对其结构和磁性进行了研究.主要结果如下:XRD数据表明,该化合物具有类普鲁士蓝的面心立方结构,a=1.178 nm.由半峰宽估算的晶粒的平均粒径约为5 nm.化合物的Tc为340 K,矫顽力HC在40～310 K范围基本保持在5～6 Oe,1.83 K时增至120 Oe.化合物具有较好的空气稳定性,空气中放置10 d后Tc仍为340 K,矫顽力Hc稍有增加.与已报道的同体系的另几个室温磁体比较,其显著的特点是,亚铁磁长程有序相与自旋玻璃态共存,自旋玻璃行为由频率依赖的交流磁化率所证实.     

钛锆钒异核双金属配合物[Cp2V(μ-η2:η4-PhC4Ph)MCp2′](M=Ti,Zr; Cp′=C5H5,C5H4SiMe3)的合成与表征

室温下, [Cp2Ti(C≡CPh)2], [Cp2Zr(C≡CPh)2]和[(C5H4SiMe3)2Zr(C≡CPh)2]分别与二茂钒作用, 合成了[Cp2V(μ-η2∶η4-PhC4Ph)MCp2′] (1, M=Ti, Cp′=C5H5; 2, M=Zr, Cp′=C5H5; 3, M=Zr, Cp′=C5H4SiMe3). 用元素分析、质谱、核磁共振谱、磁矩、红外和拉曼光谱对配合物进行了表征. 3个配合物具有相似的磁化率, 配合物3的晶体结构分析表明PhC4Ph通过内部2个碳原子键合到Cp2V上, 内部2个碳原子和外部2个碳原子均与Cp2′Zr键合, 丁二烯骨架内部的2个碳原子都具有四配位的平面结构.     

三核过渡金属配合物〔M_3~ⅢO(OOCR)_6L_3〕 (M=Cr,Fe,Mn;R=CH_3,C_2H_5,CH_2NH_2;L=C_5H_5N,H_2O)的~1H NMR性质

采用１ＨＮＭＲ谱研究了通式为〔Ｍ３ⅢＯ（ＯＯＣＲ）６Ｌ３〕＋（Ｍ＝Ｃｒ,Ｆｅ,Ｍｎ;Ｒ＝ＣＨ３,Ｃ２Ｈ５,ＣＨ２ＮＨ２;Ｌ＝Ｃ５Ｈ５Ｎ,Ｈ２Ｏ）的一系列氧心三核过渡金属配合物,主要考察其１Ｈ化学位移随金属、配体、温度、溶剂等因素变化而变化的规律。结果表明,骨架金属对化学位移的影响最大,Ｍ３Ｏ中的３个金属离子间存在反铁磁交换相互作用。对Ｍｎ配合物中顺磁中心对化学位移和线宽的影响机制的研究表明,其１Ｈ各向同性位移主要由接触作用贡献     

Theoretical study on inverse sandwiches [M(AIP)]2(C4H4) (M = V,Cr): High spin multiplicity of septet and nonet

The experimental synthesis of quintet [V(AIP)]₂(μ‐C₆H₆) and septet [Cr(AIP)]₂(μ‐C₆H₆) analogues provide a new strategy to produce high spin multiplicity by utilizing inverse sandwiches. Aiming to design higher spin multiplicity, [M(AIP)]₂(μ‐C₄H₄) (M = Cr, V) using C₄H₄ as central ligand are theoretically proposed. For [V(AIP)]₂(μ‐C₄H₄), the most stable isomer group contains the septet and the open‐shell singlet isomers, which have three unpaired electrons on each V atoms. For [Cr(AIP)]₂(μ‐C₄H₄), the most stable isomer group contains the septet and the nonet isomers, which have three and four unpaired electrons on each Cr atoms, respectively. The dissociation energies indicate that the above [M(AIP)]₂(μ‐C₄H₄) are as stable as the available [M(AIP)]₂(μ‐C₆H₆). It would be a reasonable strategy using C₄H₄ as central ligand to induce the higher spin multiplicity of inverse sandwiches.     

A density functional theory study on boundary of “superreduced” transition metal carbonyl anions [M(CO)n] (M=Cr, n=5, 4, 3, z=2, 4, 6; M=Mn, n=5, 4, 3, z=1, 3, 5; M=Fe, n=4, 3, 2, z=2, 4, 6; M=Co, n=4, 3, 2, z=1, 3, 5)

A nonlocal density functional theory (DFT) method has been applied to the calculations on optimized geometry, Mulliken atomic net charges and interatomic Mulliken bond orders as well as total bonding energies (E) in the binary transition metal carbonyl anions with different reduced states [M(CO)_n]^z− (M=Cr, n=5, 4, 3, z=2, 4, 6; M=Mn, n=5, 4, 3, z=1, 3, 5; M=Fe, n=4, 3, 2, z=2, 4, 6; M=Co, n=4, 3, 2, z=1, 3, 5). For comparison of relative stability, a relative stabilization energy D is defined as D=E([M(CO)_n]^z− )-nE(CO). The calculated C-O distances are lengthened monotonously with the increase of the anionic charge, but the M-C distances are significantly lengthened only in the higher reduced states. The relative stabilization energy calculated is a considerable negative value in the lower reduced states, but a larger positive value in the higher reduced states. The DFT calculations show that with the increase of the anionic charge, the Mulliken net charges on the M, C, and O atoms all increase, however, an excess of the anionic charge is mainly located at the central metal atom. The calculated C-O Mulliken bond orders decrease consistently with the increase of the anionic charge, but the M-C bond orders exhibit an irregular behavior. However, the total bond orders calculated clearly explain the higher reduced states to be considerably unstable. From analysis of the calculated results, it is deduced that the stability of the binary transition metal carbonyl anions [M(CO)_n]^z− studied are associated with the coordination number n and the anionic charge z, further, it is possible for the anions studied to be stable if n≥z, conversely, it is impossible when n<z.     

Effect of Ligand Field Strength on the Spin Crossover Behaviour in 5‐X‐SalEen (X=Me,Br and OMe) Based Fe(III) Complexes

The reaction of Fe(NCS)₃ prepared in situ in MeOH with 5‐X‐SalEen ligands (5‐X‐SalEen=condensation product of 5‐substituted salicylaldehyde and N‐ethylethylenediamine) provided three Fe(III) complexes, [Fe(5‐X‐SalEen)₂]NCS; X=Me ( 1 ), X=Br ( 2 ), X=OMe ( 3 ). All the complexes reveal similar structural features but a very different magnetic profile. Complex 1 shows a gradual spin crossover while complexes 2 and 3 show a sharp spin transition. The T_1/2 for complex 2 is 237 K while for complex 3 it is much higher with a value of 361 K. The spin transition temperature is shifted towards higher temperature with increasing electron‐donation ability of the ligand substituents. This experimental observation has been rationalized with DFT calculations. UV‐Vis and cyclic voltammetry studies support the fact that the electron density on the ligand increases from Me to Br to OMe substituents. To understand the change in spin states, temperature‐dependent EPR spectra have been recorded. The spin state equilibrium in the liquid state has been probed with Evans NMR spectroscopic method, and thermodynamic parameters have been evaluated for all complexes.     

Ti-48Al-2M~1-2M~2(M~1=Nb,V;M~2=Mn,Cr,V)合金电子结构

用紧束缚能带计算方法(EHT)研究了标题多元合金的能带及电子结构。发现少量的多种元素在γ-TiAl中掺杂,对合金中电荷分布的影响,具有单种元素掺杂的叠加性;选择适当的合金元素就能达到多种掺杂的性能互补。多种元素掺杂能更有效地使成键电子云趋势于球形化,Peierls力均称为化,有利于增加γ-TiAl合金的塑性和变形性。     

Organometallic Molybdenum(V) Complexes with Primary Phosphine Ligands. Syntheses,Spectroscopic Properties and Molecular Structures of [Cp°MoCl4(PH2R)] (R = But, 1‐Ad,Cy, Ph, 2, 4, 6‐Me3C6H2, 2, 4, 6‐Pri3C6H2, Cp° = C5EtMe4)

[Cp°MoCl₄] (Cp° = C₅EtMe₄) reacts with primary phosphines PH₂R to give the paramagnetic phosphine complexes [Cp°MoCl₄(PH₂R)] [Cp° = C₅EtMe₄, R = Bu^t ( 1 ), 1‐Ad (1‐Ad = 1‐adamantyl; 2 ), Cy ( 3 ), Ph ( 4 ), Mes (Mes = 2, 4, 6‐Me₃C₆H₂; 5 ), Tipp (Tipp = 2, 4, 6‐Prⁱ₃C₆H₂; 6 )]. 1 — 6 were characterized spectroscopically (IR, MS), and X‐ray crystal structures were determined for 1 — 4 and 6 . EPR investigations in liquid and frozen solution confirmed the presence of Mo^V species, and the data were used to analyze the spin‐density distribution in the first coordination sphere. Complexes 3 and 4 react with two equivalents of NEt₃ with formation of [Cp°MoCl₂(η³‐P₄Cy₄H)] ( 7 ) and [Cp°₂Mo₂(μ‐Cl)₂(μ‐P₄Ph₄)] ( 8 ), respectively, in low yield. Complexes 7 and 8 were characterized by X‐ray crystallography.     

[Ph4P][(C5H6N3O3)M(CO)5] (M = Cr,Mo, W; C5H7N3O3 = 1,3‐Dimethyl‐cyanuric Acid). Organometallic Complexes of the 1,3‐Dimethylcyanurate Ligand

1,3‐Dimethylcyanuric acid (DMCH) forms on deprotonation and reaction with TlF its thallous salt Tl[DCM] ( 2 ) which is converted to the phosphonium salt [PPh₄][DCM] ( 3 ). On the reaction with M(CO)₆, the pentacarbonylmetalate salts [Ph₄P][(DMC)M(CO)₅], M = Cr ( 4a ), Mo ( 4b ) and W ( 4c ) are obtained. IR and NMR data of 4 reveal the DMC anion ( 1 ) to have coordination properties similar to those of pyridine. The crystal structures of 4a and 4c are reported.     

Theoretical study of the structures of [M(18C6)](HFA)2 complexes (M = Ba,Sr, Pb,Cd, Mn; 18C6 = 18-crown-6; HFA = hexafluoroacetylacetonate anion)

The structures of the [M(18C6)]²⁺ cations (M = Ba, Sr, Pb, Cd, Mn) and their salts [M(18C6)](HFA)₂ and [M(18C6)](NO₃)₂ have been calculated by the density functional theory method (in the B3LYP/6-311++G** + LanL2Dz approximation). Upon geometry optimization, the gas-phase structures of compounds of different composition have been calculated; for them, the strength of binding of the central cation to the crown ether (18C6) and the degree of structural similarity have been evaluated. The structure of the [NH₄(18C6)]⁺ cation identified in a practical synthesis has also been considered. For metal cations acting as a central atom, NH ₄ ⁺ and [M(18C6)]²⁺ complex cations, as well as for intermediate and ultimate products [M(18C6)](NO₃)₂ and [M(18C6)](HFA)₂ (M = Ba, Sr, Pb, Cd, Mn), the electronic chemical potential and Pearson hardness, which enables the consideration of the propensity of various reagents to interact with each other in terms of the empirical HSAB principle (hard with hard and soft with soft), have been evaluated. Comparison of the estimates with the properties of the synthesized compounds with M = Ba, Sr, and Pb makes it possible to preliminarily verify the applicability of this principle to the systems under consideration and predict some properties of isostructural analogues important in the search for methods of synthesis of [M(18C6)](HFA)₂, where M = Cd and Mn. The possibility of establishing a correlation between the electron density of the system, stability, and hydrolytic activity of complexes has been shown.