新型环状金属Pt(Ⅱ)配合物:合成、晶体结构及光谱性质

合成了一种新的环状金属配体4-甲氧甲酰基-6-(4-甲基苯基)-2,2’-联吡啶(HL)及它的单核与双核Pt(Ⅱ)配合物[Pt(L)PPh₃](ClO₄)(1)与[Pt₂L₂(μ-dppm)](ClO₄)₂(2)(dppm=二(二苯基磷)-甲烷),并研究了它们的结构及光物理性质.配合物2的晶体结构分析表明,中心金属离子Pt(Ⅱ)呈扭曲平面正方形构型,桥配体dppm连接两个金属中心,0.3375 nm的Pt——Pt距离表明双核配合物中存在金属-金属相互作用.两配合物在～450 nm处的肩峰归属于金属到配体的电荷转移(MLCT)吸收,在固体及溶液中均观测到强烈的光致磷光发射.配合物1在固态时620 nm的低能发射归属为³(π-π)跃迁,并暗示配合物1晶体结构中存在分子间配体-配体相互作用,然而在溶液中仅观察到³MLCT发射光谱,但配合物2在固态及溶液中都观察到明显的金属和金属相互作用到配体的电荷转移(³MMLCT)发射.     

C60Ru(OCOCF3)(CO)(PPh3)配合物的合成及性能

富勒烯;钌配合物;循环伏安法;C60Ru(OCOCF3)(CO)(PPh3)配合物的合成及性能     

富勒烯配合物η2-C60[Ru(NO)(PPh3)]2的合成与表征

从1985年Kroto等[1]发现富勒烯至今, 其在化学、材料和物理等领域已有较多的研究[2～8]. 目前有关C60取代的金属小分子配合物(如羰基、亚硝酰基等)的研究方兴未艾. 而以NO为配体的亚硝酰基金属富勒烯配合物仅有数例[2,3], Green等[3]在研究以CO和NO为配体的金属富勒烯系列化合物的合成中, 认为C60不能与Ru(NO)2(PPh3)2发生反应. 本文利用Ru(NO)2(PPh3)2与C60反应首次合成出η2-C60[Ru(NO)(PPh3)]2配合物, 并对其进行了表征.     

水对二氧化碳插入TpRu(PPh3)(CH3CN)H生成甲酸根配合物的影响

分别研究了在干燥THF及H2O/THF条件下CO2与TpRu(PPh3)(CH3CN)H(Tp=Hydrotris(pyrazolyl)borate)的反应, 发现水对CO2插入TpRu(PPh3)(CH3CN)H的反应具有显著促进作用. 原位高压NMR研究显示, 在水存在下, CO2插入Ru-H键形成水合甲酸根配合物TpRu(PPh3)(CH3CN)(η1-OCHO)H2O, 其中甲酸根配体与溶剂中水分子形成分子间氢键. B3LYP水平的理论计算表明, CO2插入TpRu(PPh3)(CH3CN)H 中Ru-H键的能垒由于水的存在而显著降低; 在过渡态, CO2分子中碳原子的亲电性由于其氧原子与水分子形成氢键而得到增强. TpRu(PPh3)(CH3CN)(η1-OCHO)*H2O很快转化为另一甲酸根配合物TpRu(PPh3)(H2O)(η1-OCHO), 并与之达成平衡. 后者由于甲酸根配体与水分子配体间形成分子内氢键而稳定.     

2-苯基异喹啉及其衍生物铂(II)配合物的合成和光谱性质

合成了7种2-苯基异喹啉及其衍生物Pt(Ⅱ)配合物。 采用1H/13C NMR、TGA、X射线单晶衍射、CV、UV-Vis和PL等测试方法对配合物的结构和性能进行了表征。 结果表明,这些Pt(Ⅱ)配合物均为平面四方配位构型。 室温下,所有配合物在二氯甲烷(DCM)溶液中均发射红光,其中配合物(CzPPiQ)Pt(acac)和(CzPPiQ)Pt(dpm)为标准的红光发射,其发射源于金属到配体的电荷转移(MLCT)(407、444和463 nm)和配体中心(LC)(353、363和376 nm)的混合激发态。 配合物在DCM溶液中的光量子产率为0.02~0.06,寿命为1.78~3.33 μs。 大位阻外围取代基的引入有效抑制了分子间相互作用。     

Zn-Ln(Ⅲ)(Ln=Eu, Tb)杂核配合物的合成、 结构及光物理性质

采用溶剂热方法合成了两种具有良好发光性能的d-f异核金属配合物EuZn(C8H7O3)5(phen)(H2O)(1)和TbZn(C8H7O3)5(phen)(H2O)(2). 采用单晶X射线衍射表征了晶体结构. 结果表明, 两种配合物是同构的, 在配合物中, Zn为五配位, Ln(Ⅲ)[Ln(Ⅲ)=Eu, Tb]为八配位. 金属间通过对甲氧基苯甲酸根的羧基(—COO)基团成桥联结. 测定了配合物的紫外-可见吸收光谱、 红外光谱和荧光光谱. 讨论了配位环境对荧光性质的影响以及配合物分子内能量传递问题.     

双(二苯基膦戊烷)富勒烯合铂配合物的合成及光电性能

采用配体取代法合成了以双二苯基膦戊烷（dpppe）及C60为配体、Pt为中心金属的C60Pt(dpppe)新型富勒烯膦金属配合物。 运用质谱、元素分析、紫外-可见吸收光谱、红外吸收光谱和光电子能谱等测试技术对产物进行了表征,同时采用循环伏安法对目标产物进行氧化还原性能研究。 结果表明,C60与金属Pt配位后还原电位发生负移。 结合电子光谱数据确定了目标产物的能级结构,其最高占有轨道和最低非占轨道能级分别为5.635和3.815 eV。 还考察了目标产物在光化学电池中的光伏效应,测试结果表明,在 BQ/H2Q介质溶液中镀层厚度为 1~2 μm 时,具有较好的光电转换性能,光生电压值最高达358 mV。     

由分子筛笼内铂羰基簇合物得到的催化剂的分散度研究

由分子筛笼内包容的铂羰基簇合物[Pt_(12)(CO)_(24)]~(2-)/NaY和[Pt_9(CO)_(18)]~(2-)/NaY经还原得到的样品Pt_(12)/NaY和Pi_9/NaY的分散度用EXAFS和化学吸附进行了表征．对Pt_(12)/NaY和Pi_9/NaY，EXAFS分析分别给出R_(Pt－Pt)＝0.274 nm，配位数C.N.＝0.42和R_(Pt－Pt)＝0.274 nm配位数C.N.＝3.8，而化学吸附结果分别为H/Pt＝1.26，CO/Pt＝0.69和H/Pt＝1.24，CO/Pt＝0.64．与浸渍法制备的Pt/Al_2O_3相比小得多的Pt－Pt配位数及大的化学吸附值说明，由分子筛笼内铂羰基簇合物出发，我们得到了高分散的Pt/NaY催化剂．由于还原后原子堆积形式的变化，Pt_(12)/NaY和Pt_9/NaY的再还原羰基化不能可逆地得到与前驱体相同的铂羰基簇合物．     

异构的蒽乙烯单钌配合物:合成与表征、电化学、光谱性质及理论计算

通过9-蒽乙炔基及2-蒽乙炔基分别与有机金属氢化物羰基氯氢三(三苯基膦)钌(Ⅱ)[Ru HCl(CO)(PPh_3)_3]反应,再使用三甲基膦(PMe_3)交换配体,合成并表征了具有同分异构结构的蒽乙烯单钌配合物1和2,其中配合物2的结构还经X射线单晶衍射的确证,结合理论计算研究了其电学及光学性质。密度泛函理论(DFT)优化配合物1和2的电子结构显示,在两个异构体中钌乙烯基与蒽配体呈现明显不同的构型,前线分子轨道图显示最高已占分子轨道(HOMO)上电子离域于整个分子骨架,其中以配体蒽乙烯基所占比例为90%,表明蒽乙烯基配体参与该配合物氧化进程的比例很大。电化学实验结果表明,配合物1的氧化还原可逆性明显低于配合物2。配合物1和2及前体分子1b和2b的电子吸收光谱结果表明,配合物与前体分子相比光谱性质呈现明显变化,其在紫外区域的强吸收峰明显减弱,而在长波长方向均出现了弱而宽的吸收峰,该吸收峰已经通过含时密度泛函理论(TDDFT)计算将其归属于π→π*以及金属配位电荷转移(MLCT)跃迁吸收,均来自于HOMO→LUMO跃迁产生。荧光发射光谱揭示金属配位之后其荧光强度和荧光量子产率明显降低。CCDC:1488284,2。     

以2,3-二苯基吡嗪或2,3-二苯基喹喔啉为配体的单核和双核金属铂配合物的晶体结构与光物理性质

以2,3-二苯基吡嗪(H_2dpp)、5-甲基-2,3-二苯基吡嗪(H2mdpp)和2,3-二苯基喹喔啉(H_2dpq)为配体,乙酰丙酮(Hacac)为辅助配体,合成了一类单核和双核金属铂配合物[Pt(Hdpp)(acac)](1)、[Pt2(dpp)(acac)2](2)、[Pt(Hmdpp)(acac)](3)和[Pt(Hdpq)(acac)](4),并且得到了配合物2、3和4的晶体结构数据。通过对单核配合物1的类似物配合物3和双核配合物2的配位平面、分子扭曲程度等的晶体结构分析,我们合理地推断以2,3-二苯基吡嗪为配体的双核配合物2具有比相应的单核配合物1更加扭曲的分子平面。通过对配合物1和2的紫外-可见吸收光谱和激发光谱的比较,发现由于双核配合物2在激发态的构型变化造成了激发光谱中最低能带比相应的最低能量吸收带光谱红移了18 nm。因此,尽管双核配合物2具有与单核配合物1类似的紫外-可见吸收光谱,最低能吸收带仅比单核配合物1红移5 nm,但是双核配合物2的最大发射峰值λmax为609 nm,比单核配合物1(λmax=546 nm)红移了63 nm。双核配合物2的发射光谱红移现象与配合物的分子构型直接相关。分子扭曲程度更大的双核配合物2在激发态可能发生了一个向平面性更好的构型转变过程,从而进一步降低了激发态能量,造成了发射光谱的红移。     

电极表面结构及有机添加物对C60电还原过程的影响

研究了不同电极表面结构及有机添加剂对Ｃ６０电化学还原过程的影响。实验结果表明，富勒烯及其阴离子的电还原活性取决于电极表面结构的影响，即：ｉｐｃ（多晶）〉ｉｐｃ［Ｐｔ（１１１）］〉ｉｐｃ［Ｐｔ（１１０）］，且在Ｐｔ（１１１）及Ｐｔ（１１０）晶面上Ｃ６０＾１－及Ｃ６０＾２－的还原电位均有一定的位移。另外，实验结果还表明当溶液中分别添加苯胺及邻氨基酚时，其对Ｃ６０电还原过程的影响机理将有所不同。     

Organometallic derivatives of fullerenes: a DFT study of (eta2-Cx)[Pt(PH3)2]n (x = 60, 70, 84; n = 1-6)

To determine the relationship among curvature, patch type, and reactivity of the C-C site, a series of density functional calculations were performed on several substituted fullerenes. [6:6] pyracylene-type sites are the most reactive sites in all analyzed cages: C(60), C(70), and C(84). The binding energy between the Pt(PH(3))(2) unit and fullerene is almost independent of the size of the cage and of the number of metals coordinated on the fullerene surface. Contrarily, curvature and type of carbon-carbon bond are determinant for the coordination strength. The use of relatively large basis sets is necessary to have consistent energies.     

Developing Reagents To Orient Fullerene Derivatives. Formation and Structural Characterization of (eta(2)-C(60)O)Ir(CO)Cl(As(C(6)H(5))(3))(2)

In order to obtain crystals of fullerene oxides that are suitable for single-crystal X-ray diffraction, the reactions between C(60)O and Vaska type iridium complexes have been examined. While reaction with Ir(CO)Cl(P(C(6)H(5))(3))(2)(and with triphenylphosphine but not triphenylarsine) results in partial deoxygenation of the fullerene epoxide, reaction with Ir(CO)Cl(As(C(6)H(5))(3))(2)()()produces crystalline (eta(2)-C(60)O)Ir(CO)Cl(AsPh(3))(2).4.82C(6)H(6).0.18CHCl(3). Black triangular prisms of (eta(2)-C(60)O)Ir(CO)Cl(AsPh(3))(2).4.82C(6)H(6).0.18CHCl(3)form in the monoclinic space group P2(1)/n with a = 14.662(2) ?, b = 19.836(2) ?, c = 28.462(5) ?, and beta = 100.318(12) degrees at 123 (2) K with Z = 4. Refinement (on F(2)) of 10 472 reflections and 1095 parameters with 10 restraints yielded wR2 = 0.152 and a conventional R = 0.066 (for 7218 reflections with I > 2.0sigma(I)). The structure shows that the iridium complex is bound to a 6:6 ring junction of the fullerene with four partially occupied sites for the epoxide oxygen atom. Thus, while deoxygenation of the fullerene does not occur upon reaction with Ir(CO)Cl(AsPh(3))(2), there is a greater degree of disorder in (eta(2)-C(60)O)Ir(CO)Cl(AsPh(3))(2)than previously reported for (eta(2)-C(60)O)Ir(CO)Cl(PPh(3))(2).     

DFT studies of Pt/Au bimetallic clusters and their interactions with the CO molecule

Density functional theory (DFT) calculations were performed to study Pt/Au clusters of different size, structure, and composition as well as their interactions with a CO molecule. Among the Pt/Au isomers studied here, the planar structure is the most stable structure in many Pt compositions, although three-dimensional structures become more stable with increasing Pt composition. Furthermore, structures with the Pt atoms surrounded by Au atoms are more stable among homotops. However, these conclusions will be altered if ligands are attached to the Pt/Au bimetallic clusters, as evidenced from the results of CO adsorption. When both Au and Pt sites are exposed, CO adsorption at the Pt site is stronger. If only a Au site is available for CO adsorption, the strongest adsorption occurs at approximately 25% Pt composition, which may correlate with the experimentally observed reactivity of the core-shell structured Pt/Au nanoparticles.     

Photoreversible multiple additions of hydrogen to a highly unsaturated platinum-rhenium cluster complex

The compound Pt3Re2(CO)6(PBut3)3, 1, was obtained from the reaction of Re2(CO)10 with Pt(PBut3)2 in octane solvent at reflux. Compound 1 consists of a trigonal bipyramidal cluster of five metal atoms with three platinum atoms in the trigonal plane and the two rhenium atoms in the apical positions. The metal cluster is formally unsaturated by 10 electrons. Compound 1 sequentially adds 3 equiv of hydrogen at room temperature/1 atm to form the series of compounds Pt3Re2(CO)6(PBut3)3(mu-H)2, 2, Pt3Re2(CO)6(PBut3)3(mu-H)4, 3, and Pt3Re2(CO)6(PBut3)3(mu-H)6, 4. A small but significant kinetic isotope effect was observed, kH/kD = 1.3. The rate of addition of hydrogen is unaffected by the presence of a 20-fold excess of free PBut3 in solutions of 1. Compounds 2-4 each consist of a trigonal bipyramidal cluster of three platinum and two rhenium atoms similar to that of 1. The hydrido ligands in 2-4 bridge the platinum-rhenium bonds and are arranged to give structures having overall C2v symmetry for 2 and 3 and approximate D3h symmetry for 4. Some of the hydrido ligands were expelled from 4 in the form of hydrogen upon exposure of solutions to UV-vis irradiation to yield compound 3 and then 2 in reasonable yields, but the elimination of all hydrido ligands to yield 1 was achieved only under the most forcing UV irradiation and then only with a major loss of the complex due to decomposition. The electronic structures of 1-4 were investigated by DFT calculations. Additional DFT calculations have suggested some mechanisms for the activation of hydrogen at multicenter metal sites without ligand eliminations prior to the hydrogen additions.     

First-principles study on the reconstruction induced by the adsorption of C60 on Pt(111)

The adsorption of C60 on a Pt(111) surface and the origins of the √13 × √13R13.9° or 2√3 × 2√3R30° reconstruction of the C60/Pt(111) system have been investigated by means of first-principles calculations. In agreement with the experimental observations, our calculations reveal that the C60 molecule binds covalently on the Pt(111) surface. The C60 molecule adsorbs on the Pt(111) surface with the center of a hexagonal ring located on top of a surface Pt atom. The surface Pt atom can be removed easily, forming a Pt vacancy upon the adsorption of C60 molecule. Our calculation results show that the strong covalent bonds between C60 and the Pt(111) surface and the formation of adatom-vacancy pairs in the C60/Pt(111) system may be the main driving forces promoting the substrate reconstructing pattern observed in experiments.     

Tetranuclear platinum phosphido complexes with different structures

The addition of [NBu4]Br or [NBu4][BH4] to solutions of [Pt4(mu-PPh2)4(C6F5)4(CO)2] yields the complexes [NBu4]2[Pt4(mu-PPh2)4(mu-X)2(C6F5)4] (X=Br, H,) in which the two CO groups have been replaced by two anionic, bridging X ligands. The total valence electron counts are 64 and 60, respectively; thus, complex does not require Pt-Pt bonds, while two metal-metal bonds are present in, as their NMR spectra confirm. Also, the NMR spectra indicate a nonsymmetrical "Pt(mu-PPh2)2Pt(mu-PPh2)(mu-X)Pt(mu-PPh2)(mu-X)Pt" disposition for and. Treatment of with HX (X=Cl, Br) yields the complexes [NBu4]2[Pt4(mu-PPh2)4(mu-H)2(C6F5)3X] (X=Cl, Br,). These complexes react with [Ag(OClO 3)PPh3] with displacement of the halide and formation of [NBu4][Pt4(mu-PPh2)4(mu-H)2(C6F5)3PPh3]. Complexes maintain the same basic skeleton as, with two Pt-Pt bonds. Complex is, however, an isomer of the symmetric [NBu4]2[{(C6F5)2Pt(mu-PPh2)2Pt(mu-Br)}2], which has been prepared by a metathetical process from the well-known [NBu4]2[{(C6F5)2Pt(mu-PPh2)2Pt(mu-Cl)}2]. The comparison of the X-ray structures of and confirms the different disposition of the bridging ligands, and their main structural differences seem to be related to the size of Br- and its position in the skeleton.     

Temperature dependence of CO-tolerant hydrogen oxidation reaction activity at Pt, Pt-Co, and Pt-Ru electrodes

The temperature dependence of CO-tolerant H2 oxidation reaction (HOR) activity at Pt, Pt-Co, and Pt-Ru electrodes in 0.1 M HClO4 solution was examined with a channel flow electrode at 30 to 90 degrees C. The kinetically controlled current density (j(K)) for the HOR at Pt decreased seriously at CO overage (theta(CO)) >0.6 in the whole temperature range examined. In contrast, the Pt-Ru alloy exhibited an excellent CO tolerance: only 15% reduction in j(K) even at theta(CO) = 0.6 and 30 degrees C. The Pt-Co alloy also showed moderate CO tolerance up to 70 degrees C. It was found for these alloys that the CO adsorption rate was much slower than that of Pt and the HOR sites were not so rigidly blocked by adsorbed CO due to its enhanced mobility, resulting from their modified electronic structure of surface Pt sites. The activation energies for the apparent rate constants for the HOR were as low as 3.0 and 5.3 kJ mol(-1) at Pt and Pt-Ru, respectively, indicating that the high-temperature operation increases CO-free HOR sites as well as enhancing the HOR kinetics.     

Predicting efficient C(60) epoxidation and viable multiple oxide formation by theoretical study

The epoxidation of C(60) by various oxidizing agents such as dimethyldioxirane (DMD), methyl(trifluoromethyl)dioxirane (MTMD), and bis(trifluoromethyl)dioxirane (BTMD) has been probed computationally by the AM1 method. The computations have revealed that for the reaction forming C(60)O through a concerted "spiro" transition state, the currently used DMD involves its HOMO lone-pair and the LUMO (pi) of fullerene in an inverse electron demand fashion. This is distinct from the DMD reaction with ethylene. On the other hand, the addition of CF(3) groups lowers the LUMO (peroxide sigma) of MTMD and BTMD by virtue of negative hyperconjugation; the oxidants can then attack the fullerene nucleophilically at an increased rate to the maximum extent. These estimations have thus established that the strong electrophilic oxidizing agents remarkably enhance the fullerene epoxidation. DMD further produces C(60)O(2) and C(60)O(3) via multiple epoxidations, as C(60)O might best be produced quantitatively by MTMD and BTMD. The regiochemistry of the multiple oxidation products in which the subsequent oxidations take place at the adjacent sites is consistent with the increased nucleophilicity of the nearest double bonds attached to the prevailing epoxide function.     

Unsaturated platinum-rhenium cluster complexes. Synthesis, structures and reactivity

Two new compounds PtRe3(CO)12(PBut3)(micro-H)3, 9, and PtRe2(CO)9(PBut3)(micro-H)2, 10, were obtained from the reaction of Pt(PBut3)2 with Re3(CO)12(micro-H3), 8, at room temperature. Compound 9 contains a butterfly cluster of four metals formed by the insertion of the platinum atom from a Pt(PBut3) group into one of the hydride-bridged metal-metal bonds of 8. The three hydrido ligands are bridging ligands across each of three new Pt-Re bonds. Compound 10 contains a triangular PtRe2 cluster with two hydrido ligands; one bridges a Pt-Re bond, and the other bridges the Re-Re bond. The new compound Pt2Re2(CO)7(PBut3)2(micro-H)2, 11, was obtained from the reaction of 8 with Pt(PBut3)2 in hexane at reflux. Compound 11 was also obtained from 10 by reaction with an additional quantity of Pt(PBut3)2. Compound 11 contains a tetrahedral cluster of four metal atoms with two dynamically active hydrido ligands. A CO ligand on one of the two platinum atoms also exchanges between the two platinum atoms rapidly on the NMR time scale. Compound 11 is electronically unsaturated and was found to add hydrogen at room temperature to form the tetrahydrido cluster complex, Pt2Re2(CO)7(PBut3)2(micro-H)4, 12. Compound 12 has a structure similar to 11 but contains one triply bridging hydrido ligand, two edge bridging hydrido ligands, and one terminal hydrido ligand on one of the two platinum atoms. A kinetic isotope effect D/H of 1.5(1) was determined for the addition of H2 to 11. Hydrogen can be eliminated from 12 by heating to 97 degrees C or by the application of UV-vis irradiation at room temperature. Compound 12 adds CO at room temperature to yield the complex Pt2Re2(CO)8(PBut3)2(micro-H)4, 13, which contains a planar cluster of four metal atoms with a Pt-Pt bond and four edge bridging hydrido ligands. Compounds 11 and 12 react with Pt(PBut3)2 to yield the known five metal cluster complexes Pt3Re2(CO)6(PBut3)3(micro-H)2, 14, and Pt3Re2(CO)6(PBut3)3(micro-H)4, 15, respectively. Density functional calculations confirm the hydride positions in the lowest energy structural isomers of 11 and 12 and suggest a mechanism for H2 addition to 11 that occurs on the Pt atom with the lower coordination number.