含BF配体的三核锇羰基化合物Os_3(BF)_3(CO)_n(n=9,8,7)稳定性的理论研究

采用MPW1PW91和BP862种密度泛函方法对中性三核Os_3(BF)_3(CO)_n(n=9,8,7)化合物进行理论计算研究,优化得到20个低能异构体.研究发现,8个配位饱和的Os_3(BF)_3(CO)_9具有4个能量接近的最低能量异构体,其中能量最低的异构体为D_(3h)对称性,其边桥配位的BF基团在3个Os原子构成的平面上.配位不饱和的Os_3(BF)_3(CO)_8的6个异构体中,以含有2个面桥配位形式BF基团的异构体能量最低,而由配位饱和Os_3(BF)_3(CO)_9的能量最低异构体失去1个CO后得到C2v对称性异构体的能量较之稍高约19k J/mol.计算得到的6个配位不饱和Os_3(BF)_3(CO)_7的异构体中有2个能量接近的最低能量异构体.能量最低的异构体含有3个边桥配位形式的BF基团.研究发现,含有面桥配位形式的CO基团的异构体比含有面桥配位形式BF基团的异构体能量更高.离解能研究表明,Os_3(BF)_3(CO)_n(n=9,8)失去1个CO和分别分裂为单核的Os(BF)(CO)_4或Os(BF)(CO)_3及相应的双核Os_2(BF)_2(CO)_n(n=6,5)所需能量较高,表明这2类化合物具有一定的热力学稳定性.频率分析表明,与边桥配位形式的BF基团相比,面桥配位形式的BF基团的νBF更低,与CO基团相比,BF与过渡金属原子形成的σ配键较弱而π反馈键则较强.     

BO基杂配位铁羰基化合物Fe_2(BO)_2(CO)_n(n=9,5)的配位特性研究

含硼的双原子配体(如BO、BF等)稳定性差,有关BO基配位取代金属羰基化合物的实验研究和理论研究均较少,对配位过饱和及高度不饱和过渡金属配位体系的配位研究还鲜见报道.本文采用两种密度泛函方法 B3LYP和BP86对BO基杂配位的过饱和及高度不饱和铁羰基化合物Fe2(BO)2(CO)n(n=9,5)的配位特性进行了研究.研究结果表明,在配位过饱和Fe2(BO)2(CO)9中,两个Fe原子间距较大,没有明显直接成键作用.其低能构型都是桥连结构且更倾向于CO桥而不是BO桥,BO基多以端配位的形式出现;由于其体系配位过饱和的特征,优化的低能构型中出现了BO基耦合于端位CO基的配位结构29-6S和29-8S.在配位高度不饱和Fe2(BO)2(CO)5体系中,所有低能构型也都是桥连结构但倾向于BO桥而不是CO桥,显现BO基中氧原子的碱性比CO基中氧原子的碱性更强;由于其配位高度不饱和,构型25-1S、25-4T和25-5T中存在两个3-电子给体桥?2-μ-BO配位;25-2T、25-3T和25-6T中存在两个"首尾相连"的3-电子给体"–B–O–"桥;结构25-1T中出现了由两个BO配体耦合形成的4-电子给体反式双硼双氧(B2O2)配体.无论从单羰基离解能还是单核离解能来看,Fe2(BO)2(CO)5的热力学稳定性都远比Fe2(BO)2(CO)9高,可望是一个潜在的合成目标.     

配位不饱和双核钌羰基化合物Ru2(CO)n(n=7,6)的DFT计算研究

对配位不饱和双核钌羰基化合物Ru2(CO)n(n=7,6)在BP86/DZP++和MPW1PW91/DZP++ 理论水平下进行了量子化学理论计算研究, 优化得到16个单态和三态异构体, 并讨论其键的性质. 得到的n=7,6基态分别是Cs和C2v构型的单态, 均含有2个配位的桥羰基. 对其离解能的计算表明, 相对于断裂金属钌-钌键而生成2个配位不饱和单核羰基化合物都更容易失去一个羰基.     

钒的羰基化合物V(CO)_n的电子结构研究

用限制性的CNDO/2法研究具有开壳层结构V(CO)_x(n=1～6)的各种构型和轨道.给出轨道能级相关图,阐明了各种构型的关系及稳定性.     

含CS配体的单、双核钌羰基化合物Ru（CS）（CO）n（n=4,3）和Ru2（CS）2（CO）n（n=7,6,5,4）的理论研究

采用2种密度泛函方法MPW1PW91和BP86对中性单核Ru(CS)(CO)n(n=4,3)及双核Ru2(CS)2(CO)n(n=7,6,5,4)化合物进行理论计算研究,优化出25个异构体.研究发现,单核配位饱和Ru(CS)(CO)4的2个异构体14-1,14-2能量接近,其配体呈三角双锥型.对称性为C2v的异构体14-1能量稍低,其CS基团在三角双锥赤道面上.单核配位不饱和Ru(CS)(CO)3的能量最低异构体是由14-1失去1个赤道面上的CO得到的,其对称性为Cs.配位饱和的双核Ru2(CS)2(CO)7能量最低异构体27-1结构中有3个桥配位基团,其中2个是CS基团.配位不饱和的Ru2(CS)2(CO)6存在2个能量接近的异构体,即含3个桥配位基团对称性为Cs的异构体26-1和含2个桥配位基团的异构体26-2.它们的CS基团都是桥配位形式.Ru2(CS)2(CO)5的能量最低异构体25-1含有两个桥配位CS基团,其中一个是4电子供体.而Ru2(CS)2(CO)4的能量最低异构体24-1的两个桥配位CS基团都是4电子供体.在上述各个异构体中,单核Ru(CS)(CO)n(n=4,3)的能量最低异构体的CS基团都位于配体三角双锥及缺顶点结构的赤道面上,双核Ru2(CS)2(CO)n(n=7,6,5,4)能量最低异构体的CS基团都以桥配位形式和Ru原子相连,且在配位不饱和Ru2(CS)2(CO)n(n=5,4)的能量最低异构体中都存在4电子供体CS基团.离解能研究表明,单核配位饱和的Ru(CS)(CO)4具有一定的热力学稳定性.双核的Ru2(CS)2(CO)n(n=7,6,5)失去1个CO或者分裂为单核的Ru(CS)(CO)4或Ru(CS)(CO)3所需能量都较高,但Ru2(CS)2(CO)6和Ru2(CS)2(CO)5有发生歧化反应的趋势,而Ru2(CS)2(CO)7具有一定的热力学稳定性.     

钛,锆和铪羰基化合物M(CO)_n(M=Ti,Zr,Hf;n=4～7)的理论研究

利用密度泛函方法对标题化合物的平衡几何、热化学及振动频率进行了理论预测,发现这3种金属原子都有相似的M(CO)n(n=4～7)结构.全局最低构型对M(CO)7都是单态C3v戴帽八面体7S-1,对M(CO)6都是三重态D3d畸变八面体6T(而对应的单重态M(CO)5仅比它低不到21 kJ·mol-1).对M(CO)n(n=5,4)都是三重态6S-1,其构型分别为从6T中移去1个或2个CO基的衍生物5T和4T.此外,五重态的D3h的三角双锥M(CO)5和单态的Td四面体M(CO)4以及能量更高的含有C和O同时与金属成键的独特配位CO基的M(CO)6和M(CO)3也被发现.最后,给出M(CO)7→M(CO)6+CO反应的离解能.并讨论了金属18价电子的Ti(CO)7存在的可能性.     

SiO2·(CO)n(n=1～2)结构和属性的理论研究

用密度泛函理论详细地研究了SiO2·(CO)n(n=1～2)的结构和属性.研究表明,SiO2·CO是一个T形的具有C2v对称性的分子,SiO2·(CO)2具有C2对称性的分子;频率计算结果与实验值一致,CO在与SiO2成键过程中,C-O伸缩振动频率有所增加,说明静电势在复合过程中起了重要作用;基组重叠误差(BSSE)修正在计算相互作用能时不可忽视,相互作用能和解离能的计算以及NBO分析表明,SiO2·(CO)2中的SiO2与CO之间的作用相对SiO2·CO来说较弱;SiO2和CO2与CO的成键特点不同,主要是缘于SiO2与CO2的能隙不同.     

羰基原子簇化合物M3(CO)12(M=Fe,Ru,Os)的激光解离研究

在自制的仪器上以冲激光溅射铁、钌、锇的三核羰基原子簇化合物。由原位质谱观察和分析溅射产生的正负离子。比较了解离碎片及分布发现羰基锇原子簇化合物具有特殊的结构稳定性。它们不仅具有很强的金属键,而且锇与羰基分子还形成了很强的配位键。     

(H_2O)_n(n=0～2)催化HS和HOCl反应机理的理论研究

在CCSD(T)/6-311+G(3df,2p)//M06-2X/6-311+G(3df,2p)水平上研究了(H_2O)n(n=0~2)催化HS和HOCl的反应机理.结果表明,HS与HOCl反应中HS夺取HOCl上的H原子形成产物H_2S和ClO.在无水催化时,该反应存在2种不同的路径(分别经过过渡态TS1和TS2,二者互为顺反结构),对应的能垒分别为100.28和100.91kJ/mol,到达产物(H_2S+ClO)需吸收18.99kJ/mol能量,反应不易发生;在单个水分子参与时,水分子可通过形成弱相互作用或者作为H原子转移桥梁影响反应机理,获得了4种水催化路径,能垒(间于53.97~92.39kJ/mol之间)均低于无水催化过程.同时发现,在反应到达产物前,水分子可以与产物形成中间体IM,IM相对能仅为0.46kJ/mol,有利于产物形成;有2个水分子参与反应时,找到了3条催化路径,最优反应路径过渡态TS7的能垒为45.05kJ/mol,低于无水催化过程,相比单个水分子最优路径能垒(53.97kJ/mol)并无显著降低.     

Au-2n(n=1,2)催化CO氧化反应机理的理论研究

采用密度泛函理论B3LYP方法研究了金团簇阴离子Au-2和Au-4催化CO氧化反应的详细机理.计算结果表明,O2分子比CO分子更容易吸附剑金团簇上.第二分子CO能有效降低较强O-O键断裂所需能量.CO氧化反应过程需要两个CO分子协同进行.Au-2和Au-4催化CO氧化反应均通过碳酸根中间体进行,活化能分别为0.607和0.658 eV.Au-4和Au-2都能在常温下有效催化CO氧化反应,这些结果与以前的实验和理论研究一致.     

Homoleptic mononuclear and binuclear osmium carbonyls Os(CO)n(n = 3-5) and Os2(CO)n (n = 8, 9): comparison with the iron analogues

The structures and energetics of the experimentally known Os(CO)n ( n = 3-5), Os2(CO)9, and Os2(CO)8 have been investigated using density functional theory. For Os(CO)5, the lowest-energy structure is the singlet D(3h) trigonal bipyramid. However, the C(4v) square pyramid for Os(CO)5 lies only approximately 1.5 kcal/mol higher in energy, suggesting extraordinary fluxionality. For the coordinatively unsaturated Os(CO)4 and Os(CO)3, a D(2d) strongly distorted tetrahedral structure and a Cs bent T-shaped structure are the lowest-energy structures, respectively. For Os2(CO)9, the experimentally observed singly bridged Os2(CO)8(mu-CO) structure is the lowest-energy structure. A triply bridged Os2(CO)6(mu-CO)3 structure analogous to the known Fe2(CO)9 structure is a transition state rather than a true minimum and collapses to the singly bridged global minimum structure upon following the corresponding normal mode. An unbridged (OC)5Os --> Os(CO)4 structure with a formal Os --> Os dative bond analogous to known stable complexes of the type (R3P)2(OC)3Os --> W(CO)5 is also found for Os2(CO)9 within 8 kcal/mol of the global minimum. The global minimum for the coordinatively unsaturated Os2(CO)8 is a singly bridged (OC)4Os(mu-CO)Os(CO)3 structure derived from the Os2(CO)9 global minimum by loss of a terminal carbonyl group. However, the unbridged structure for Os2(CO)8 observed in low-temperature matrix experiments lies only approximately 1 kcal/mol above this global minimum. In all cases, the triplet structures for these osmium carbonyls have significantly higher energies than the corresponding singlet structures.     

Theoretical study on homoleptic mononuclear and binuclear ruthenium carbonyls Ru(CO) n (n= 3–5) and Ru2(CO) n (n = 8, 9)

Science China Chemistry - Homoleptic mononuclear and binuclear ruthenium carbonyls Ru(CO) n (n = 3–5) and Ru2(CO) n (n = 8,9) have been investigated using density functional theory. Sixteen...     

羰基硼化合物B2n(CO)n (n＝1～6)的理论研究

运用密度泛函理论(DFT)的B3LYP/6-31G*方法, 对羰基硼化合物B_2n(CO)_n (n＝1～6)各种可能的结构进行了优化,对它们的几何构型、电子态、振动频率、核独立化学位移(NICS)和B₂CO的分子轨道进行了理论研究, 得到了B_2n(CO)_n (n＝1～6)结构的稳定性信息. 在它们的基态结构中, 羰基的配位方式是端配位(μ₁-CO), B_2n(CO)_n (n＝1～5)的基态构型是线形或平面结构, B₁₂(CO)₆的基态构型则较为复杂. B_2n(CO)_n (n＝1～3)的基态是三重态, B_2n(CO)_n (n＝4～6)的基态是单重态. 振动频率和轨道的研究为实验提供了重要的理论依据.     

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.     

New Binuclear Copper Complexes [(9S3)Cu(CN)Cu(9S3)]Xn (X=BF4, n=1; X=TCNQ,n=2) (9S3=1, 4, 7‐trithiacyclononane): Syntheses,Crystal Structures and Magnetic Properties

The binuclear Cu complex salts of 1, 4, 7‐trithiacyclononane (9S3) with an inorganic anion (BF₄)^‐ and with an organic radical anion TCNQ^‐ (7, 7′, 8, 8′‐tetracyanoquinodimethanide) were synthesized and their molecular and crystal structures were examined in connection with the magnetic properties. The new complex cation [Cu(9S3)CN(9S3)Cu]⁺ varies its charges and magnetic properties depending on the counter anions; [Cu(9S3)CN(9S3)Cu](BF₄) ( 1 ) was obtained as diamagnetic colorless crystals, while [Cu(9S3)CN(9S3)Cu](TCNQ)₂ ( 2 ) was obtained as dark blue crystals with antiferromagnetic properties. Complex 1 crystallized in the monoclinic space group C2/c with a = 26.863(2), b = 7.0878(5), c = 13.4864(8) Å, β = 116.318(2)°. Complex 2 crystallized in the triclinic space group P1¯ with a = 12.521(1), b = 20.2698(8), c = 8.0205(4) Å, α = 100.688(4), β = 93.846(5), γ = 94.953(4)°. Both complexes are comprised of cyano‐bridged two Cu(9S3) ions with tetrahedral coordination. The X‐ray structural study revealed that 1 has two crystallographically equivalent copper(I) atoms, while 2 has two crystallographically independent Cu^I/II sites. The two Cu^I/II sites could not be distinguished from the X‐ray structural study. For 2 the IR spectra show that both crystallographically independent TCNQ species were monoanions and are strongly dimerized due to π‐stacking, which well explains their diamagnetic contribution to the magnetic susceptibility and the highly insulating property of this salt. The temperature‐dependent magnetic susceptibility of 2 showed a deviation from the Curie‐Weiss behaviour around 60 K, which indicates a strong antiferromagnetic intermolecular interaction between the copper complexes and that such intermolecular interaction should partly occur via the TCNQ radical anion dimer.     

Heteronukleare Metallatomcluster der Typen X4−n[SnM(CO)4P(C6H5)3]n und M2(CO)8 [μ-Sn(X)M (CO)4P(C6H5)3]2 aus Umsetzungen von SnX2 mit M2(CO)8[P(C6H5)3]2 (X = Halogen; M = Mn,Re; n = 2, 3)

Heteronuclear Metal Atom Clusters of the Types X_4?n[SnM(CO)₄P(C₆H₅)₃]_n and M₂(CO)₈[μ-Sn(X)M(CO)₄P(C₆H₅)₃]₂ by Reaction of SnX₂ with M₂(CO)₈[P(C₆H₅)₃]₂ (X = Halogene; M = Mn, Re; n = 2, 3) The compounds of the both types X_4?n[SnM(CO)₄P(C₆H₅)₃]_n (n = 3; M = Mn; X = F, Cl, Br, I. n = 2: M = Mn, Re; X = Cl, Br, I) and M₂(CO)₈[μ-Sn(X)M(CO)₄P(C₆H₅)₃]₂ (M = Mn; X = Cl, I. M = Re; X = Cl, Br, I) are prepared by reaction of SnX₂ with M₂(CO)₈[P(C₆H₅)₃]₂ (M = Mn, Re). Their IR frequencies are assigned. In Re₂(CO)₈[μ-Sn(Cl)Re(CO)₄P(C₆H₅)₃]₂ the central molecule fragment contains a planar Re₂Sn₂ rhombus with a transannular Re? Re bond of 316.0(2) pm. Each of the Sn^IV atoms is connected with the terminal ligands Cl and Re(CO)₄P(C₆H₅)₃. These ligands are in transposition with respect to the Re₂Sn₂ ring. The mean values for the remaining bond distances (pm) are: Sn? Re = 274.0(3); Sn? Cl = 243(1), Re? C = 176(5), Re? P = 242.4(9), C? O = 123(5). The factors with an influence on the geometrical shape of such M₂Sn₂ rings (M = transition metal) are discussed.     

Use of the Cationic Fragments [Ru(η5-C5H5) (MeCN)3]+ and [M(η6-C6H5R)(MeCN)3]+ (M=Os, Ru; R=H, Me) as Ionic Coupling Reagents in the Synthesis of the Clusters [Os4M2(CO)12(η6-C6H5R)], [Os4M(CO)12(η6-C6H6)(Au2dppm)] and [Os5Ru(CO)15(η5-C5H5)(AuPPh3)]*

The clusters [H₂Os₄M(CO)₁₂eta⁶-C₆H₆)] (M=Os, Ru) may be deprotonated to generate anions [Os₄M(CO)₁₂eta⁶-C₆H₆)]^2- which react with [M′eta⁶-C₆H₅R) (MeCN)₃]²⁺(M^′=Os, Ru; R=H, Me) to give the bicapped tetrahedral clusters [Os₄(CO)₁₂MM′eta⁶-C₆H₅R)₂]. Whereas [Os₄(CO)₁₂M₂eta⁶-C₆H₆)₂] (M=Os, Ru) have one Meta⁶-C₆H₆) unit in a site connected to three other metals, {3}, and one in a site connected to four other metals, {4}, [Os₄(CO)₁₂OsRueta⁶-C₆H₆)₂] has the Rueta⁶-C₆H₆) unit in the {3} site irrespective of whether the Os or Ru anion is capped. Coupling of these anions with Au₂dppm yields [Os₄M(CO)₁₂eta⁶-C₆H₆)(Au₂dppm)] (M=Os, Ru), which have the arene ligand in the axial site of a trigonal bipyramid and the digold unit capping two faces. Reduction of [H₂Os₅(CO)₁₅] with K/Ph₂CO and coupling with [Rueta⁵-C₅H₅)(MeCN)₃]²⁺yields the monoanion [Os₅(CO)₁₅Rueta⁵-C₅H₅)]^? which reacts with [AuPPh₃]⁺ generating [Os₅(CO)₁₅Rueta⁵-C₅H₅)(AuPPh₃)] with the “Ru(C₅H₅)” unit in the terminal {3} site.