Density functional study of S(N) 2 substitution reactions for CH(3) Cl + CX(1) X(2•-) (X(1) X(2) = HH, HF, HCl, HBr, HI, FF, ClCl, BrBr, and II)

A systematic investigation on the S_N2 displacement reactions of nine carbene radical anions toward the substrate CH₃Cl has been theoretically carried out using the popular density functional theory functional BHandHLYP level with different basis sets 6‐31+G (d, p)/relativistic effective core potential (RECP), 6‐311++G (d, p)/RECP, and aug‐cc‐pVTZ/RECP. The studied models are CX¹X^2?? + CH₃Cl → X²X¹CH₃C^? + Cl^?, with CX¹X^2?? = CH₂^??, CHF^??, CHCl^??, CHBr^??, CHI^??, CF₂^??, CCl₂^??, CBr₂^??, and CI₂^??. The main results are proposed as follows: (a) Based on natural bond orbital (NBO), proton affinity (PA), and ionization energy (IE) analysis, reactant CH₂^?? should be a strongest base among the anion‐containing species (CX¹X^2??) and so more favorable nucleophile. (b) Regardless of frontside attacking pathway or backside one, the S_N2 reaction starts at an identical precomplex whose formation with no barrier. (c) The back‐S_N2 pathway is much more preferred than the front‐S_N2 one in terms of the energy gaps [ΔE(front)?ΔE(back)], steric demand, NBO population analysis. Thus, the back‐S_N2 reaction was discussed in detail. On the one hand, based on the energy barriers (ΔE and ΔE) analysis, we have strongly affirmed that the stabilization of back attacking transition states (b‐TSs) presents increase in the order: b‐TS‐CI₂ < b‐TS‐CBr₂ < b‐TS‐CCl₂ < b‐TS‐CHI < b‐TS‐CHBr < b‐TS‐CHCl < b‐TS‐CF₂ < b‐TS‐CHF < b‐TS‐CH₂. On the other hand, depended on discussions of the correlations of ΔE with influence factors (PA, IE, bond order, and ΔE), we have explored how and to what extent they affect the reactions. Moreover, we have predicted that the less size of substitution (α‐atom) required for the gas‐phase reaction with α‐nucleophile is related to the α‐effect and estimated that the reaction with the stronger PA nucleophile, holding the lighter substituted atom, corresponds to the greater exothermicity given out from reactants to products. © 2012 Wiley Periodicals, Inc. J Comput Chem, 2012     

High-resolution observation and analysis of the I(2) (+) A(2)Π(3∕2,u)-X (2)Π(3∕2,g) system

Rotationally resolved absorption spectra of I(2) (+) were recorded in 12 065-13 062 cm(-1) region by employing optical heterodyne velocity modulation absorption spectroscopy. In total, 4054 lines were assigned to 24 bands in the A(2)Π(3∕2,u)-X(2)Π(3∕2,g) system spanning the vibrational levels υ(') = 1-4 and υ(n) (') = 11-19. The assigned lines were globally fitted and an error of 0.003 cm(-1) was obtained. Rotational constants, B(υ), were used to derive equilibrium parameters B(e) (') = 0.03977725(77) cm(-1), a(e) (') = 1.1819(24)×10(-4) cm(-1), r(e) (') = 2.584386(25) A? of the X(2)Π(3∕2,g) state, and B(e) (') = 0.0305787(37) cm(-1), a(e) (') = 1.2353(23)×10(-4) cm(-1), r(e) (') = 2.94758(18) A? of the A(2)Π(3∕2,u) state. Vibrational energies were used to derive ω(e) (') = 239.0397(55) cm(-1), ω(e)x(e) (') = 0.64951(87) cm(-1) of the X(2)Π(3∕2,g) state and ω(e) (') = 138.103(11) cm(-1), ω(e)x(e) (') = 0.45027(34) cm(-1) of the A(2)Π(3∕2,u) state. The A(2)Π(3∕2,u) (υ(n) = 13) state was found to be rotationally perturbed by the a(4)Σ(1/2,u) (-) (υ(n) = 17) state through second-order spin-orbit coupling.     

Synthese,Kernresonanzspektren und Schwingungsspektren der Hexamethyltrisilane und Pentamethyltrisilane (XMe2Si)2SiMe2 und (XMe2Si)2SiMeX (XH,F, Cl,Br, I,Ph, OMe)

The syntheses, IR, Raman and ²⁹Si spectra of the title compounds are reported. SiSi force constants, calculated with the aid of normal coordinate analyses, are compared with ²⁹Si²⁹Si coupling constants.     

Stabilities,Electronic Structures,and Bonding Properties of Iron Complexes (E1E2)Fe(CO)2(CNArTripp2)2 (E1E2=BF,CO, N2, CN−, or NO+)**

The coordination of 10-electron diatomic ligands (BF, CO N₂) to iron complexes Fe(CO)₂(CNAr^Tripp2)₂ [Ar^Tripp2=2,6-(2,4,6-(iso-propyl)₃C₆H₂)₂C₆H₃] have been realized in experiments very recently (Science, 2019 , 363, 1203–1205). Herein, the stability, electronic structures, and bonding properties of (E₁E₂)Fe-(CO)₂(CNAr^Tripp2)₂ (E₁E₂=BF, CO, N₂, CN⁻, NO⁺) were studied using density functional (DFT) calculations. The ground state of all those molecules is singlet and the calculated geometries are in excellent agreement with the experimental values. The natural bond orbital analysis revealed that Fe is negatively charged while E₁ possesses positive charges. By employing the energy decomposition analysis, the bonding nature of the E₂E₁–Fe(CO)₂(CNAr^Tripp2)₂ bond was disclosed to be the classic dative bond E₂E₁→Fe(CO)₂(CNAr^Tripp2)₂ rather than the electron-sharing double bond. More interestingly, the bonding strength between BF and Fe(CO)₂(CNAr^Tripp2)₂ is much stronger than that between CO (or N₂) and Fe(CO)₂(CNAr^Tripp2)₂, which is ascribed to the better σ-donation and π back-donations. However, the orbital interactions in CN⁻→Fe(CO)₂(CNAr^Tripp2)₂ and NO⁺→Fe(CO)₂(CNAr^Tripp2)₂ mainly come from σ-donation and π back-donation, respectively. The different contributions from σ donation and π donation for different ligands can be well explained by using the energy levels of E₁E₂ and Fe(CO)₂(CNAr^Tripp2)₂ fragments.     

Syntheses,crystal structures,and electrochemical studies of Fe2(CO)6(μ-PPh2)(μ-L) (L = OH,OPPh2, PPh2)

Reaction of Fe₃(CO)₁₂ and Ph₂PH in the presence of Et₃N in THF at 0?°C immediately forms Fe₂(CO)₆(μ-PPh₂)(μ-OH) (1), Fe₂(CO)₆(μ-PPh₂)(μ-k²O,P-OPPh₂) (2), and Fe₂(CO)₆(μ-PPh₂)₂ (3) in yields of 25, 14, and 19%, respectively. Experiments confirm that Et₃N shortens the reaction time. The absence of O₂ hinders the formation of 2. The presence of H₂O can increase the yield of 1. Their structures have been determined by X-ray crystallography and the complexes have been completely characterized by EA, IR, and ¹H, ¹³C, ³¹P NMR. Electrochemical studies reveal that they exhibit catalytic H₂-producing activities.     

(Ph3P)2,Co(CO)2Cl和(dppe-P,P)2CO(CO)+的分子轨道研究

本文对(PH3P)2, Co(CO)2Cl和(dppe-P,P)2CO(CO)+(dppe=Ph2CH2CH2PPh2)五配位C2O对称性模型化合物进行了分轨道研究, 结果表明, 钴的3d轨道很少参与成键, 钴的4s, 4P与配体的S,P轨道通过形式上的二电子三中心键和二电子二中心键的相互作用构成五配位, 此外, 还解释了这两种化合物不同稳定性的原因。     

Aquanitrilotris(methylenephosphonato)bis(dimercury(I)) hydrate, [(Hg2)2(H2O)N(CH2PO3)3H2] · H2O: Synthesis,structure, and properties

A reaction of dimercury(I) dinitrate with nitrilotris(methylenephosphonic acid), N(CH₂PO₃)₃H₆, gave the complex [(Hg₂)₂(H₂O){N(CH₂PO₃)₃H₂}] · H₂O. The crystals of the complex are triclinic, space group \(P\bar 1\), Z = 2, a = 8.3436(3), b = 9.0744(3), c = 11.1124(4) Å, α = 91.875(3)°, β = 104.452(3)°, γ = 92.195(3)° (CIF file CCDC no. 1051860). The atoms of either dimercury cation are coordinated differently, making up a distorted tetrahedron and a distorted trigonal bipyramid. The ligand is coordinated to the Hg atoms through seven donor atoms: six (out of nine) O atoms and a N atom. The coordination involves the formation of chelate rings: two four-membered, three five-membered, a six-membered, and an eight-membered ring (CIF file CCDC no. 1051860).     

Ir(CO)Cla(Ph2Ppy)2HgClb(HgCl2)c (a,b=1, 2, c=0, 1)的Ir-Hg相互作用和氧化还原反应性质

应用密度泛函理论(DFT)的PBE0方法, 金属原子采用SDD基组, H、C、O和N原子采用6-31G*基组, P和Cl原子采用6-311G*基组, 对单核配合物Ir(CO)Cl(Ph2Ppy)2(1), 双核配合物Ir(CO)(Cl)2(Ph2Ppy)2HgCl(2)、Ir(CO)Cl(Ph2Ppy)2HgCl2(3)和Ir(CO)(Cl)2(HgCl2)(Ph2Ppy)2HgCl(4)进行结构优化, 并在优化的基础上采用基组重叠误差(BSSE)校正计算相互作用能, 通过自然键轨道(NBO)和前线轨道分析研究Ir-Hg相互作用和氧化还原反应的实质. 通过计算发现, Ir(CO)Cl(Ph2Ppy)2与HgCl2发生氧化还原反应得到的产物2和4比非氧化还原产物3稳定. Ir-Hg相互作用强度顺序为3<4<2, 且随着Ir-Hg相互作用强度增大, HOMO轨道中Ir和Hg成分逐渐趋于接近. 配合物2和4都具有一对Ir-Hg成键与反键轨道, 其成键轨道的组成分别为0.5985sd0.06Hg+0.8012sd2.48Ir和0.5794sd0.05Hg+0.8151sd2.48Ir, 但3中Ir与Hg的相互作用较弱, 只存在弱相互作用(电荷转移作用), 表现为nIr→nHg的直接作用和σIr—P(1)→nHg、σIr—C(1)→nHg的间接作用.     

Synthesis,Characterization and Crystal Structure of (PhCH2)2Sn(S2CENt2) and (PhCH2)2Sn(S2CNC4H8)2

Two new dibenzyltin bisditiocarbamates(PhCH2)2 Sn(S2CNEt2)2(1) and (PhCH2)2 Sn(S2CNC4H8)2(2) were synthesized by the reaction of dibenzyltin dichloride with dithiocarbamates and characterized by elemental analysis ,IR,^1H NMR and MS spectra.The crystal structures were determined by X-ray single crystal diffraction analysis.In both complexes,the tin atom is six-coordinated in a distorted octahedral configuration.In the crystals of 1,the molecular packing in unit cell reveals that the two adjacent molecules are symmetrically linked to each other in dimers by two Sn S interactions of 0.3816nm.In the crystals of 2,the molecules are packed in the unit cell in one-dimensional chain structure linked by weaker intermolecular S S conmtacts.     

Die Kristallstrukturen von β-TaNi3, Ta(Cu,Al)2, Nb(Cu,Al)2 und Ta6(Cu,Al)7

Zusammenfassung Neben der bekannten Phase TaNi₃ mit TiCu₃-Typ wird eine Kristallart gleicher Zusammensetzung gefunden, die mit TiAl₃ isotyp ist. Ta(Cu, Al)₂ und Nb(Cu, Al)₂ kristallisieren im MgZn₂-Typ (Laves-Phase). Ta₆(Cu, Al)₇ ist eine -Phase.     

Au(II)化合物[Au(CH_2)_2PH_2]_2X_2(X=F,Cl,Br,I)的量子化学理论研究

采用从头计算HF,MP2方法和密度泛函理论,对Au(II)系列化合物[Au(CH2)2PH2]2X2(X=F,Cl,Br,I)的几何结构、电子结构和振动频率进行了研究.研究表明Au的5d和6s电子参与Au—Au以及Au—X之间的成键.Au—Au,Au—X键强烈的电子相关作用使HF方法不适于该体系的研究,BP86和B3LYP两种泛函给出较大的Au—Au和Au—X键长,而MP2方法和局域的密度泛函方法则给出了合理的结构参数.局域密度泛函方法计算得到的Au—Au键和Au—X键振动频率也与实验数据符合较好.还运用含时密度泛函理论计算了[Au(CH2)2PH2]2X2的电子激发能,对分子在紫外-可见光谱范围内的电子跃迁进行了分析,考察了卤素配体对激发能的影响,并结合分子轨道能级的变化对此给予了解释.     

Synthesis,crystal structure and properties of the dimeric copper(II) complex, [Cu2(Hboa)2(H2O)2] · (ClO4)2 (H2boa = biacetyl oxime azine)

The crystal structure of the polyhydrazone dioxime-containing dimeric copper(II) (polyhydrazone dioxime: HON=CMe[CMe=NN=CMe] _n CMe=NOH) complex, [Cu₂(Hboa)₂(H₂O)₂] · (ClO₄)₂ (1) (H₂boa = biacetyl oxime azine) has been determined. Complex (1) contains an unusual six-membered ring, which is composed of two oxime groups and two Cu^II ions. The variable temperature magnetic susceptibility of (1) in the 5–300 K range has been interpreted in terms of a Cu^II dimer. The magnetic behavior shows that the bridging six-membered ring mediates very strongly in the antiferromagnetic exchange interaction, with the fitting value J = –361(1) cm^–1 and the e.p.r. g-value of 2.193.     

Two isotypic transition metal germanophosphates M(II)4(H2O)4[Ge(OH)2(HPO4)2(PO4)2] (M(II) = Fe, Co): synthesis, structure, Mössbauer spectroscopy, and magnetic properties

Synthetic, structural, thermogravimetric, M?ssbauer spectroscopic, and magnetic studies were performed on two new isotypic germanophosphates, M(II)(4)(H(2)O)(4)[Ge(OH)(2)(HPO(4))(2)(PO(4))(2)] (M(II) = Fe, Co), which have been prepared under hydro-/solvo-thermal conditions. Their crystal structures, determined from single crystal data, are built from zigzag chains of M(II)O(6)-octahedra sharing either trans or skew edges interconnected by [GeP(4)O(14)(OH)(4)](8-) germanophosphate pentamers to form three-dimensional neutral framework structure. The edge-sharing M(II)O(6)-octahedral chains lead to interesting magnetic properties. These two germanophosphates exhibit a paramagnetic to antiferromagnetic transition at low temperatures. Additionally, two antiferromagnetic ordering transitions at around 8 and 6 K were observed for cobalt compound while only one at 19 K for the iron compound. Low-dimensional magnetic correlations within the octahedral chains are also observed. The divalent state of Fe in the iron compound determined from the M?ssbauer study and the isothermal magnetization as well as thermal analyses are discussed.     

Synthesis,properties, and reactions of enantiomerically pure,chiral fluorous phosphines of the formula (menthyl)P(CH2CH2(CF2)n−1CF3)2 (n=6, 8)

Reactions of (menthyl)PH₂ and H₂CCHR_f6 (menthyl=1R,3R,4S; R_fn=(CF₂)_n−1CF₃) or H₂CCHR_f8 (AIBN, refluxing THF) give (menthyl)PH(CH₂CH₂R_fn) and then (menthyl)P(CH₂CH₂R_fn)₂ (n=6, 7; n=8, 8), but with purification or other difficulties at each stage. Reactions of (menthyl)PCl₂ with IMgCH₂CH₂R_fn give, under careful conditions, analytically pure 7 or 8 in 28–32% yields after distillation. Some R_fn(CH₂)₄R_fn also form. These represent the first chiral (and non-racemic) fluorous phosphines. Reactions of 7 or 8 with [Ir(COD)Cl]₂ and CO give trans-[(menthyl)P(CH₂CH₂R_fn)₂]₂Ir(Cl)(CO) (n=6, 71%; 8, 51%) as analytically pure yellow oils. Their IR ν_CO values show the donor/acceptor properties of 7 and 8 to be intermediate between those of P((CH₂)₃R_f8)₃ and P((CH₂)₄R_f8)₃. The CF₃C₆F₁₁:toluene partition coefficients of 7 and 8 (27°C, 78.4:21.6 and 93.7:6.3) are distinctly lower than those of P((CH₂)₂R_fn)₃ (n=6, 98.8:1.2; n=8, >99.7:<0.3), reflecting the replacement of a linear C₈–C₁₀ group that is ca. 75–80% fluorinated by a cyclic C₁₀ terpenyl group. Reactions of 7 or 8 with [Rh(COD)Cl]₂ give [(menthyl)P(CH₂CH₂R_fn)₂]Rh(Cl)(COD) (n=6, 69%; 8, 70%) as orange crystallizable oils.     

Crystal Structure of (Hg, Ce, Cu)(Sr, Pr)2(Pr, Sr)Cu2O6+δ and (Hg, \square )(Sr, Pr)2(Pr, Sr)2Cu3O8+δ Phases

This paper reports on the refined compositions and crystal structures of two phases from the homologous series (Hg, M)(Sr, Pr)₂(Pr, Sr)_k-1Cu_kO_2k+2+ with k = 2 (Hg-1212) — (Hg_0.44(2)Ce _0.31 ⁴⁺ Cu_0.25)(Sr_0.90(3)Pr_0.10)₂(Pr_0.52(3)Sr_0.48)Cu_2.00O_7.00 (a = 3.8634(1), c = 12.2030(8) , space group P4/mmm) with k = 3 (Hg-1223) — (Hg_0.29(1) )(Sr_0.67(2)Pr_0.33)₂(Pr_0.61(2)Sr_0.39)₂Cu_3.00O_9.32(8) or (Hg_0.29(1) )(Sr_0.61(4)Pr_0.39)₂(Pr_0.51(4)Sr_0.49)₂Cu_3.00O_9.00 (with a fixed content of superstoichiometric oxygen O(4) in the phase) ( is a vacancy; a = 3.8294(9), b = 3.8567(6), c = 15.2763(44) , space group Pmmm). The implausibly high content of oxygen in the Hg-1223 phase (refinement I) is attributed either to O–O bond formation or to the possible presence of a minor amount of copper in a defect position of Hg; the inclusion of the latter in structure refinement leads to a better reproduction of the real structure but increases the R indices. The crystal-chemical analysis of the title phases and a comparison with the available data for analogous phases indicates that the composition of the crystallographic positions is related to structural features, in particular, to the coordinates of (Hg, M) and superstoichiometric oxygen, whose content depends on the degree of substitution of strontium ions by praseodymium ions. Reasons for the orthorhombic distortion of the Hg-1223 phase are discussed. The absence of superconductivity is explained by the nonoptimal formal charge (FC) of copper, which depends on the oxygen content in the phase.     

Crystal Structure of Binuclear Manganese(Ⅲ) Complex with Schiff-base Ligand,〔Mn_2(C_(22)H_(22)N_2O_2)_2(EtOH)_2 (bipy)〕(ClO_4)_2

1INTRODUCTIONThecoordinationchemistryofmanganeseinthe 2, 3and 4oxidationstatesisreceivingconsiderableattentionduetothebio1ogicalimportanceoftheseions(1i.Anattractivesystemformode1ingthestructureandreactivityofsomemanganoenzymesisbinuclearMn(M)complexescontainingpolydentateSchiffbaseligands.Bothphotochemicalwateroxidationtogeneratedioxygen"'andacid-pro-motedhydrogenperoxideproductiont3ihavebeenreportedforsuchdimer.Wereportherethestructureofthetitlecomplex.2EXPERIMENTAL2.lSynthesisof…     

CRYSTAL STRUCTURE AND LUMINESCENCE OF (4, 4′ -DIMETHYL-2, 2′ -BIPYRIDINE)-TRIS(BENZOATE)EUROPIUM(III)

Abstract

A mixed ligand europium complex, [Eu(BA)₃dmbpy]₂, has been prepared, where BA = benzoate and dmbpy = 4, 4′-dimethyl-2, 2′-bipyridine. The complex crystallizes in the tri-clinic system, space group P ^? ₁. Its structure has been determined using X-ray diffraction methods. The two europium ions in the molecule are held together by four carboxylate groups of benzoic acid and each europium ion is further bonded to one bidentate carboxylate group and one 4, 4′-dimethyl-2, 2′-bipyridine molecule. Excitation and luminescence spectra observed at 77 K show that the europium site in the crystal has low symmetry and changes of the chemical surroundings of the europium ion in the molecule depend mainly on the flexibility of 4, 4′-dime-thyl-2, 2′-bibyridine.     

Synthesis and Crystal Structure of N, N'''''''',N''''''''-Tris-(2-oxynaphthalidene)-tris-(2-iminoethyl) Amine

1 INTRODUCTION Schiff’s bases are well known ligands representedby many bi-, tri-, tetra-, and hexa-dentate example-es[1], but heptadentate ligands are relatively rare[2, . 3]We have reported a copper complex of tetradentateSchiff’s bases[4]…     

Supramolecular Cd(II) complexes with (E)-N,N′-bis(2-pyridyl)iminoisoindoline (2-pyimiso): synthesis,X-ray structures,Hirshfeld surface analyses,and DFT study of [CdX2(2-pyimiso)2] (X = Cl or NCS)*

The paucity of coordination entities bearing (E)-N,N′-bis(heteroaryl)iminoisoindolines has prompted us to investigate coordination modes and supramolecular features of (E)-N,N′-bis(2-pyridyl)iminoisoindoline (2-pyimiso), a versatile iminobis(pyridyl) ligand. In this article we report the synthesis, spectroscopic characterization and crystal structure analysis of two Cd(II) : 2-pyimiso (1?:?2) bis-adducts, [CdX₂(2-pyimiso)₂] [X = Cl (1) or NCS (2)]. Our X-ray structural results reveal that 1 exhibits distorted tetrahedral coordination (four-coordinate geometry index τ₄ = 0.92), whereas 2 displays six-coordinate Cd(II) and two four-membered chelate rings (bite angles = 52.5°), each comprising one Cd–N_py [2.247(2) Å] bond and one Cd?N_imine [2.809(21) Å] secondary interaction. Remarkably, in 2 each 2-pyimiso unit binds to Cd(II) according to an unusual bidentate coordination. The contributions of the Cd–N and Cd–Cl bond valences to the total metal valence for both 1 and 2 have been evaluated to confirm the coordination modes of 2-pyimiso, which can be interpreted in terms of Jørgensen’s principle of symbiosis. X-ray structure and Hirshfeld surface analyses have shown that the crystal structure of 1 is determined by two perpendicular 1-D chains formed by weak hydrogen bonds along the a- and c-axes, whereas the supramolecular architecture of 2 exhibits 2-D sheets parallel to the ab-plane interconnected by C–H?π interactions along the c-axis. A vibrational analysis of both products has been conducted at the DFT B3LYP-D3/LACV3P** level of calculation.