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.     

配合物[Fe(CO)x(Ph2Ppy)y(HgCl2)z](x=3, 4; y=1, 2; z=0, 1, 2)的Fe-Hg相互作用及31P化学位移的理论研究

用密度泛函理论PBE0法计算配合物[Fe(CO)x(Ph2Ppy)y(HgCl2)z](1: x=4, y=1, z=0; 2: x=3, y=2, z=0; 3: x=4, y=1, z=1; 4: x=3, y=2, z=1; 5: x=4, y=1, z=2; 6: x=3, y=2, z=2)的几何构型, 用PBE0-GIAO法计算配合物1~6的31P化学位移. 计算结果表明, 含2个Ph2Ppy的配合物5和6的Fe—Hg相互作用略大于含单个Ph2Ppy的配合物3和4. 含2个HgCl2的配合物4和6存在Fe—Hg σ键, 比含单个HgCl2的配合物3和5的Fe—Hg相互作用强, 配合物3和5的Fe—Hg相互作用以Fe→Hg和Fe←Hg离域为主. 配合物3中Fe的负电荷比5的小, 故配合物5的Fe—Hg相互作用比配合物3的强且Fe→Hg离域比较显著, 而配合物3的Fe←Hg离域更显著. Fe—Hg相互作用增大了双核配合物中P核周围的电子密度, 其31P化学位移比相应的单核配合物小, 且含2个HgCl2的双核配合物的31P化学位移更小. 含单个Ph2Ppy的配合物的31P化学位移小于含2个Ph2Ppy的配合物.     

[M6Om(C25N4H18)n]2-(M=W, Mo; n=1, 2; m=17,18)的二阶非线性光学性质的理论研究

运用密度泛函理论(DFT)的BP86方法, 对[M6Om(C25N4H18)n]2-(M=W, Mo; n=1, 2; m=17,18)进行了几何结构优化, 其中Mo系列结构化合物优化的几何结构与实验值吻合较好. 在净电场为零的条件下, 运用DFT/LB94方法计算了体系的二阶非线性光学系数β值: 体系1和2的βvec值分别为154.4×10-30和124.8×10-30 esu. 表明它们具有较大的二阶非线性光学系数, 且Mo系列比W系列的β值大. 而体系3和4的βvec值分别为218.0×10-30和191.8×10-30 esu. 体系3和4的βvec值分别比体系1和2的大, 表明增加给体的数目有利于提高NLO响应, 但都小于它们的2倍.     

(MN)nHm(M=Ga,In; n=1-4; m=1, 2)团簇的结构与稳定性

采用密度泛函理论(DFT)的B3LYP方法, 在6-31G**和Lanl2dz水平上分别对(MN)nHm(M=Ga, In; n=1-4; m=1, 2)进行了优化和振动频率计算. 得到了上述团簇的最稳定构型、H原子的结合能以及它们的能隙. 结果表明, (MN)nH(M=Ga, In; n=1-4)的基态构型均为双重态, (MN)nH2(M=Ga, In; n=1-4)的基态构型均为单重态; 当氢的个数为1时, 加在N原子上比加在M(M=Ga, In)原子上稳定, 如有N3单元, 那么加在N3单元两侧的构型是相同的, 且它是最稳定的; 当氢的个数为2时, 除n=1外, 分别加在两个N原子上的构型是最稳定的, 如有N3单元, 那么分别加在N3单元分离最远的两个N原子的构型是最稳定的. GaNH、(GaN)3H 和InNH的结合能和能隙都很大, 说明这些团簇都有很高的稳定性.     

金属串配合物(n,m)[Cr3(PhPyF)4Cl2](n=2, 3, 4; m=2, 1, 0)的配位结构及其与电场的关系

应用密度泛函理论BP86 方法研究具有分子导线潜在应用的金属串配合物(n, m)[Cr₃(PhPyF)₄Cl₂](HPhPyF=N, N'-苯基吡啶基甲脒; n=2, 3, 4; m=2, 1, 0)的配位结构及其受电场作用的影响, n、m分别表示PhPyF-的苯环在左侧和在右侧的配体个数. 结果表明: (1) 零电场下, 四个PhPyF-的(2, 2)、(3, 1)和(4, 0)三种配位方式能量差别很小, 为竞争态, (2, 2)最稳定. (4, 0)结构中两端轴向配体Cl 均可与Cr 配位, 且Cl₄―Cr1 键比Cl5―Cr3键更强, 若作为分子器件可与电极结合, 这与(4, 0)[CuCuM(npa)₄Cl][PF₆](M=Pd, Pt; Hnpa=2-萘啶苯胺)靠近苯环一端的轴向配体无法与M配位不同. (2) 在(2, 2)、(3, 1)和(4, 0)中, Cr₃⁶⁺链均具有三中心三电子离域σ键, 但离域性逐渐减弱. 随四个PhPyF-配位方式趋于一致, 分子极性逐渐增大, 由Cl₄指向Cl5(Z)方向, Cr1的α自旋密度增大, Cr2 的β和Cr3 的α自旋密度减小. (3) 分子的几何结构和电子结构在电场下发生规律性变化, 在-Z方向电场作用下, (3, 1)、(4, 0)电子移动方向与极性方向相同, 使分子的键长、自旋密度、电荷和能隙变化显著性均大于Z方向电场, 且极性越大变化越显著, 有利于提高分子导电性.     

Synthesis and characterization of (smif)2M(n) (n = 0, M = V, Cr, Mn, Fe, Co, Ni, Ru; n = +1, M = Cr, Mn, Co, Rh, Ir; smif =1,3-di-(2-pyridyl)-2-azaallyl)

A series of Werner complexes featuring the tridentate ligand smif, that is, 1,3-di-(2-pyridyl)-2-azaallyl, have been prepared. Syntheses of (smif)(2)M (1-M; M = Cr, Fe) were accomplished via treatment of M(NSiMe(3))(2)(THF)(n) (M = Cr, n = 2; Fe, n = 1) with 2 equiv of (smif)H (1,3-di-(2-pyridyl)-2-azapropene); ortho-methylated ((o)Mesmif)(2)Fe (2-Fe) and ((o)Me(2)smif)(2)Fe (3-Fe) were similarly prepared. Metatheses of MX(2) variants with 2 equiv of Li(smif) or Na(smif) generated 1-M (M = Cr, Mn, Fe, Co, Ni, Zn, Ru). Metathesis of VCl(3)(THF)(3) with 2 Li(smif) with a reducing equiv of Na/Hg present afforded 1-V, while 2 Na(smif) and IrCl(3)(THF)(3) in the presence of NaBPh(4) gave [(smif)(2)Ir]BPh(4) (1(+)-Ir). Electrochemical experiments led to the oxidation of 1-M (M = Cr, Mn, Co) by AgOTf to produce [(smif)(2)M]OTf (1(+)-M), and treatment of Rh(2)(O(2)CCF(3))(4) with 4 equiv Na(smif) and 2 AgOTf gave 1(+)-Rh. Characterizations by NMR, EPR, and UV-vis spectroscopies, SQUID magnetometry, X-ray crystallography, and DFT calculations are presented. Intraligand (IL) transitions derived from promotion of electrons from the unique CNC(nb) (nonbonding) orbitals of the smif backbone to ligand π*-type orbitals are intense (ε ≈ 10,000-60,000 M(-1)cm(-1)), dominate the UV-visible spectra, and give crystals a metallic-looking appearance. High energy K-edge spectroscopy was used to show that the smif in 1-Cr is redox noninnocent, and its electron configuration is best described as (smif(-))(smif(2-))Cr(III); an unusual S = 1 EPR spectrum (X-band) was obtained for 1-Cr.     

MH~+(M=Fe,Co,Ni)催化二氧化碳的氢化反应

在密度泛函理论的B3LYP水平下计算了MH~+(M=Fe,Co,Ni)催化二氧化碳的氢化反应.研究表明,氢转移至C上要比转移至O上容易得多.探讨不同泛函方法对反应的影响,从CCSD(T)的计算结果可见,与Co H~+和Ni H~+相比,Fe H~+对H转移至C上的活性较高.电子结构分析表明,反应过程中氢转移为氢负离子转移.     

叠氮化合物C6H6-n(N3)n(n=1~6)的密度泛函理论研究

运用密度泛函理论, 在B3LYP/6-31G*水平上, 对叠氮化合物C6H6-n(N3)n(n=1~6)进行理论计算, 并对所得到的几何结构进行了振动频率分析. 计算结果表明, 这些化合物是热力学稳定的. 基于自然键轨道理论, 分析了稳定结构的电荷分布及成键情况. 在不破坏苯环和叠氮基的原则下, 设计等键反应计算了这些化合物的生成热, 结果表明, 标题化合物的生成热都很高, 且随着叠氮基数目的增加而线性增大.     

(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.     

CnBδ(δ=0, ±1; n =1～6)团簇的结构、稳定性和光谱

采用密度泛函理论(DFT)的B3LYP方法,在6-31G*和6-311＋G(3df)水平上对C_nB(n=1～6)团簇及其阴离子和阳离子的几何构型和电子结构进行了优化和振动频率计算.得到了C_nB(n=1～6)团簇的电离能,绝热电子亲合势以及C_nB^δ(δ=0,±1)团簇的能隙.结果表明C_nB^－(n=1～6)团簇的基态构型均为线形,这与等电子的C_n簇合物的结构是一致的; C_nB(n=1～6)团簇的基态构型中,除C₂B为不对称的三角形,C₆B为具有C_2v对称性的环状结构外,其余均为线形结构.阳离子团簇中n=2、3、6的基态结构具有C_2v对称性外,其它几个均为线形结构.从几何参数和振动频率上发现,采用密度泛函B3LYP方法在6-311＋G(3df)和6-31G*两种基组上计算得到的键长参数和振动频率非常接近,说明B3LYP方法在计算C_nB簇合物结构参数上对于基组的选择是不太敏感的.通过对C_nB(n=1～6)的光电子能谱性质的研究发现,C₄B容易获得一个电子形成阴离子团簇,但失去一个电子是很困难的,这与实验上观测到的结果非常吻合.     

PdYn±(n=0, 1, 2, 3)分子离子的结构与稳定性

在Pd和Y原子相对论有效原子实势和基函数SDD下, 使用密度泛函理论B3LYP方法对PdYn±(n=0, 1, 2, 3)分子离子的势能曲线与稳定性进行计算研究, 结果表明, PdY分子和PdY−, PdY2−, PdY3−与PdY+分子离子的基态电子状态分别为X2Σ、X1Σ、X2Σ、X1Σ、X1Σ, 能稳定存在, 势能函数可用Murrell-Sorbie函数表达, 并计算得到相应的力常数与光谱数据; PdY2+和PdY3+分子离子的基态分别为X2Σ和X1Σ, 是亚稳定态, PdY3+分子离子的三重态是排斥态, 不能稳定存在.     

Monodisperse MFe2O4 (M = Fe, Co, Mn) nanoparticles

High-temperature solution phase reaction of iron(III) acetylacetonate, Fe(acac)(3), with 1,2-hexadecanediol in the presence of oleic acid and oleylamine leads to monodisperse magnetite (Fe(3)O(4)) nanoparticles. Similarly, reaction of Fe(acac)(3) and Co(acac)(2) or Mn(acac)(2) with the same diol results in monodisperse CoFe(2)O(4) or MnFe(2)O(4) nanoparticles. Particle diameter can be tuned from 3 to 20 nm by varying reaction conditions or by seed-mediated growth. The as-synthesized iron oxide nanoparticles have a cubic spinel structure as characterized by HRTEM, SAED, and XRD. Further, Fe(3)O(4) can be oxidized to Fe(2)O(3), as evidenced by XRD, NEXAFS spectroscopy, and SQUID magnetometry. The hydrophobic nanoparticles can be transformed into hydrophilic ones by adding bipolar surfactants, and aqueous nanoparticle dispersion is readily made. These iron oxide nanoparticles and their dispersions in various media have great potential in magnetic nanodevice and biomagnetic applications.     

[M(N)X2]-(M=Ru, Os; X=S2C6H4, mnt)的电子结构和光谱性质的理论研究

利用密度泛函理论(DFT)中的B3LYP方法优化了氮化钌和氮化锇配合物[M(N)X2]-[M=Ru, Os; X=S2C6H4, mnt(maleonitriledithiolate)]的基态几何结构, 得到的几何参数与实验结果吻合得很好. 采用TD-DFT方法, 得到了配合物在CH3CN溶液中的激发态电子结构和电子吸收光谱. 利用SCRF方法中的CPCM模型来模拟溶剂化效应. 研究结果表明, 配合物1~4在CH3CN溶液中的吸收跃迁性质相似, 低能吸收均被指认为LMCT和LLCT的混合跃迁, 高能吸收均被指认为ILCT/LLCT跃迁.     

(BCO)+n(n=1-12)团簇的结构与稳定性

用密度泛函理论(DFT)的B3LYP方法, 在6-31G*水平上对(BCO)⁺_n(n=1-12)团簇的几何结构、电子结构、振动频率等性质进行了理论研究. 结果表明, (BCO)⁺_n团簇的基态结构均为羰基端配位(μ₁-CO)结构, 且含三元环和五元环数目越多或四元环和六元环的数目越少, 相应的结构越稳定. 能量分析得到, n 为奇数的(BCO)⁺_n团簇比n为偶数的稳定.     

CnAl (n=2-11)团簇的结构特征与稳定性

采用密度泛函理论(DFT)的B3LYP方法, 在6-311++G**水平上对CnAl(n=2-11)团簇的几何构型和电子结构进行了结构优化和振动频率计算. 结果表明, n=2的CnAl团簇基态结构为Al原子与两个C原子相连形成的环状结构, n=3-11均为Al原子端基配位的线状结构. 通过对基态结构的能量分析, 得到了n为偶数的CnAl团簇比n为奇数团族稳定的结论.     

Phosphido cobalt carbonyl clusters Pn[Co(CO)3]4−n (n = 1, 2, 3)

The P_n[Co(CO)₃]_4?n (n = 1, 2, 3) tetrahedral clusters have been prepared and characterized. The very unstable PCo₃(CO)₉ can be stabilized in the form of (CO)₄FePCo₃(CO)₉     

Synthesis and characterization of quasi-two-coordinate transition metal dithiolates M(SAr*)2 (M = Cr, Mn, Fe, Co, Ni, Zn; Ar* = C6H3-2,6(C6H2-2,4,6-Pri3)2

A sequence of first row transition metal(II) dithiolates M(SAr)(2) (M = Cr(1), Mn(2), Fe(3), Co(4), Ni(5) and Zn(6); Ar = C(6)H(3)-2,6-(C(6)H(2)-2,4,6-Pr(i)(3))(2)) has been synthesized and characterized. Compounds 1-5 were obtained by the reaction of two equiv of LiSAr with a metal dihalide, whereas 6 was obtained by treatment of ZnMe(2) with 2 equiv of HSAr. They were characterized by spectroscopy, magnetic measurements, and X-ray crystallography. The dithiolates 1, 2, and 4-6 possess linear or nearly linear SMS units with further interactions between M and two ipso carbons from C(6)H(2)-2,4,6-Pr(i)(3) rings. The iron species 3, however, has a bent geometry, two different Fe-S distances, and an interaction between iron and one ipso carbon of a flanking ring. The secondary M-C interactions vary in strength in the sequence Cr(2+) approximately Fe(2+) > Co(2+) approximately Ni(2+) > Mn(2+) approximately Zn(2+) such that the manganese and zinc compounds have essentially two coordination but the chromium and iron complexes are quasi four and three coordinate, respectively. The geometric distortions in the iron species 3 suggested that the structure represents the initial stage of a rearrangement into a sandwich structure involving metal-aryl ring coordination. The bent structure of 3 probably also precludes the observation of free ion magnetism of Fe(2+) recently reported for Fe{C(SiMe(3))(3)}(2). DFT calculations on the model compounds M(SPh)(2) (M = Cr-Ni) support the higher tendency of the iron species to distort its geometry.     

荷电(±1)对二十面体X_(13)(X=Cr,Mn,Fe,Co)团簇的稳定性与磁性的影响

采用基于密度泛函理论的计算方法,对正二十面体金属X13(X=Cr,Mn,Fe,Co)中性和荷电团簇进行了全面的结构优化计算,研究了荷电对团簇的稳定性和磁性的影响.结果表明:荷负电能够使团簇的稳定性增强;荷电对不同团簇的原子间距离的影响不同;同时荷电对不同团簇磁性的影响也是不一样的,尤其是荷负电能够使Fe13和Co13团簇的磁性大大增强;荷电对不同团簇磁性的影响不是通过原子间距离的变化来实现的,而是受到原子内部电荷的转移和杂化程度的影响.