[MAl5]+ (M=Si,Ge,Sn,Pb)体系结构和稳定性的理论研究

利用B3LYP和CCSD(T)(单点)方法, 研究了含Si, Ge, Sn, Pb的六原子体系[MAl₅]⁺中各个异构体的结构及稳定性. 研究结果表明, 尽管与[CAl₅]⁺一样也具有18个价电子, 但[MAl₅]⁺(M=Si, Ge, Sn, Pb)体系并不存在具有平面五配位结构的异构体, 其能量的全局极小点为具有C_s对称性的蝶形异构体Int1, 这是由于中心原子M(Si, Ge, Sn, Pb)较大的体积显著破坏了[MAl₅]⁺中平面五配位结构的稳定性所致.     

119Sn Mössbauer spectral studies in Sn(IV) and organotin(IV) substituted oxinates

Several Sn(IV) and organotin(IV) compounds of the type SnL₂X₂(X = Cl and HL = 5-acetyl-, benzol-, or phenylazo-, 8-quinolinol), SnX₄ · 2HL′(X = Cl or Br and HL′=8-quinolinol-N-Oxide), R₂SnL₂(R = CH₃, C₂H₅, C₄H₉, C₈H₁₇ or C₆H₅) and R₃SnL(R = C₆H₅) have been synthesized and characterized. The ^119mSn Mössbauer spectra of these compounds have been recorded at 77°K and probable structures from the Mössbauer parameters are inferred. R₂SnL₂ chelates (Q.S = ca. 2.0 mm/sec.) are considered to have the two R-groups occupying cis-positions in the octahedral structure. The Mössbauer spectra of the compounds, SnX₄·2HL′ have been resolved graphically and the quadrupole splitting values (ca. 0.75 mm/sec.) strongly suggest trans-configuration for the Sn(IV) tetrahalide adducts.     

Intramolecular N→Sn coordination in tin(II) and tin(IV) compounds based on enantiopure ephedrine derivatives

The syntheses and molecular structures of the intramolecularly coordinated tin(II) compounds {CH(2)N(Me)CH(Me)CH(Ph)O}(2)SnL (2, L = lone pair; 4, L = W(CO)(5); 5, L = Cr(CO)(5)) and of the related hydroxido-substituted tin(IV) compound [{CH(2)N(Me)CH(Me)CH(Ph)O}(2)Sn(OH)](2)O, 6a, are reported. Also reported are the molecular structures of the enantiopure N,N'-ethylenebis-(1R,2S)-ephedrine, {CH(2)N(Me)CH(Me)CH(Ph)OH}(2) (1), and its hydrobromide {CH(2)N(Me)CH(Me)CH(Ph)OH}(2)·HBr (1a).     

Electrophilic Substitution Co(II)→M(II) (M = Mn,Ni, Cu,Zn, Cd) in Co2[Fe(CN)6] Gelatin-Immobilized Matrices

Electrophilic substitutions Co(II) M(II) (M = Mn, Ni, Cu, Zn, Cd) in cobalt(II) hexacyanoferrate(II) gelatin-immobilized matrices in contact with aqueous solutions of corresponding chlorides MCl₂ were studied. As a result of this contact, Co(II) was shown to be replaced to some extent by Ni(II), Cu(II), Zn(II), or Cd(II) and to give heteronuclear cobalt(II) hexacyanoferrates(II) and two-charge ions. A complete substitution of Co(II) or the formation the respective mononuclear hexacyanoferrate(II) M₂[Fe(CN)₂] was observed in neither of the studied systems Co(II) M(II). No Co(II) Mn(II) substitution was observed, even though the immobilized matrix was in contact with a solution for a long time.     

An unprecedented coordination mode of the orotate ligand in novel polynuclear cadmium(II)–orotate complexes

Two novel carboxylate-bridged Cd(II)–orotate polynuclear complexes with 2-(2-ethylamino)pyridine (2-etapy), [Cd(μ-HOr)(2-etapy)]_n (1), and N,N-diethylethylenediamine (N,N-eten) ligands, {[Cd(μ-HOr)(H₂O)(N,N-eten)]·H₂O}_n (2) (H₃Or = orotic acid), have been synthesized and characterized by TGA–evolved gas analysis (TGA–EGA), IR spectroscopy and single crystal X-ray diffraction techniques. The orotate ligand acts as a bridging ligand with two different coordination modes, showing an unprecedented tetradentate coordination mode. The HOr ligand simultaneously chelates Cd(II) ions through the carboxylate oxygen, deprotonated pyrimidine nitrogen atoms and carboxyl oxygen atoms as a tetradentate ligand in 1. In complex 2, the HOr ligand bridges two Cd(II) ions through the carboxylate oxygen and deprotonated pyrimidine nitrogen atoms and oxygen atom of a carboxylate group of a neighbouring complex unit. Three-dimensional (3D) supramolecular structures are generated by hydrogen-bonding, and π···π and C–H···π interactions between the closest chains in both complexes.     

Molecular Ln(III)−H−E(II) Linkages (Ln=Y,Lu; E=Ge,Sn, Pb)

Following the alkane-elimination route, the reaction between tetravalent aryl tintrihydride Ar*SnH₃ and trivalent rare-earth-metallocene alkyls [Cp*₂Ln(CH{SiMe₃}₂)] gave complexes [Cp*₂Ln(μ-H)₂SnAr*] implementing a low-valent tin hydride (Ln=Y, Lu; Ar*=2,6-Trip₂C₆H₃, Trip=2,4,6-triisopropylphenyl). The homologous complexes of germanium and lead, [Cp*₂Ln(μ-H)₂EAr*] (E = Ge, Pb), were accessed via addition of low-valent [(Ar*EH)₂] to the rare-earth-metal hydrides [(Cp*₂LnH)₂]. The lead compounds [Cp*₂Ln(μ-H)₂PbAr*] exhibit H/D exchange in reactions with deuterated solvents or dihydrogen.     

Electronic structure of the surface compounds ≡SiOElCl3 (El, = C,Si, Ge,Sn) and their thermal stability

The SCF MO LCA0 method in the MNDO approximation has been used to consider the electronic structure of the surface compounds SlODlCl₃ (El = C, Si, Ge, Sn), modelled by extended clusters. The thermal stabilities of these groups are compared and conclusions ore drawn about the probable mechanism of the interaction of the surface silanol groups of SiO₂ with ElCl₄ molecules.Institute for Surface Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 1, pp. 19–22, January–February, 1991. Original article submitted March 11, 1990.     

Tunability of the M(II)M(III)/M(II)(2) and M(III)(2)/M(II)M(III) (M=Mn, Co) couples in bis-μ-O,O'-carboxylato-μ-OR bridged complexes

A comparison of the electrochemical properties of a series of dinuclear complexes [M(2)(L)(RCO(2))(2)](+) with M = Mn or Co, L = 2,6-bis(N,N-bis-(2-pyridylmethyl)-sulfonamido)-4-methylphenolato (bpsmp(-)) or 2,6-bis(N,N-bis(2-pyridylmethyl)aminomethyl)-4-tert-butylphenolato (bpbp(-)) and R = H, CH(3), CF(3) or 3,4-dimethoxybenzoate demonstrates: (i) The electron-withdrawing sulfonyl groups in the backbone of bpsmp(-) stabilize the [M(2)(bpsmp)(RCO(2))(2)](+) complexes in their M(II)(2) oxidation state compared to their [M(2)(bpbp)(RCO(2))(2)](+) analogues. Manganese complexes are stabilised by approximately 550 mV and cobalt complexes by 650 mV. (ii) The auxiliary bridging carboxylato ligands further attenuate the metal-based redox chemistry. Substitution of two acetato for two trifluoroacetato ligands shifts redox couples by 300-400 mV. Within the working potential window, reversible or quasi-reversible M(II)M(III)? M(II)(2) processes range from 0.31 to 1.41 V for the [Co(2)(L)(RCO(2))(2)](+/2+) complexes and from 0.54 to 1.41 V for the [Mn(2)(L)(RCO(2))(2)](+/2+) complexes versus Ag/AgCl for E(M(II)M(III)/M(II)(2)). The extreme limits are defined by the complexes [M(2)(bpbp)(CH(3)CO(2))(2)](+) and [M(2)(bpsmp)(CF(3)CO(2))(2)](+) for both metal ions. Thus, tuning the ligand field in these dinuclear complexes makes possible a range of around 0.9 V and 1.49 V for the one-electron E(M(II)M(III)/M(II)(2)) couple of the Mn and Co complexes, respectively. The second one-electron process, M(II)M(III)? M(III)(2) was also observed in some cases. The lowest potential recorded for the E°(M(III)(2)/M(II)M(III)) couple was 0.63 V for [Co(2)(bpbp)(CH(3)CO(2))(2)](2+) and the highest measurable potential was 2.23 V versus Ag/AgCl for [Co(2)(bpsmp)(CF(3)CO(2))(2)](2+).     

Theoretical studies on the band structures of superconducting solid compounds: Nb3X (X=Si, Ge, Sn, Pb)

The band structures of several analogous superconducting A-15 type solid compounds, Nb3X (X=Si, Ge, Sn, Pb), have been calculated by use of the tight-binding method within the Extended Huckel approximation (EHT). By analysis of their energy bands, densities of states and crystal orbital overlap populations, the dependence of the superconducting transition temperatures (Tc) on the electronic structures and bondings is qualitatively elucidated.     

The vibrational spectra of (CH3)3MCCCCM(CH3)3, with M = C,Si, Ge,or Sn

Infrared spectra from 200 to 4000 cm⁻¹ and Raman spectra from 80 to 4000 cm⁻¹ have been recorded for the molecules (CH₃)₃MCCCCM(CH₃)₃ with M = C, Si, Ge, or Sn. Solid samples and solutions in several solvents have been used. Assignments of the fundamentals were made on the assumption of D_3d symmetry, which proved quite satisfactory. In all, 140 of the 188 spectroscopically-active fundamentals for the four molecules have been assigned.The in-phase CC stretch is 115–135 cm⁻¹ higher than the out-of-phase one. This is in sharp contrast to cumulated double bonds, where the in-phase stretch is roughly half the out-of-phase one. A rationalization of this is given.     

Ion-Exchange Processes M(II) → Fe(III) and Fe(III) → M(II) in Metal Hexacyanoferrate(II) Gelatin-Immobilized Matrices (M = Mn,Co, Ni,Cu, Zn,Cd)

Ion-exchange reactions M²⁺ Fe³⁺ and Fe³⁺ M²⁺ (M = Mn, Co, Ni, Cu, Zn, Cd) were studied in metal(II) hexacyanoferrate(II) gelatin-immobilized matrices M₂[Fe(CN)₆] in contact with aqueous FeCl₃ solutions and Fe₄[Fe(CN)₆]₃ in contact with aqueous MCl₂ solutions. It was shown that in both cases, M²⁺ was replaced by Fe³⁺ and Fe³⁺ was replaced by M²⁺ to some extent, but no complete replacement was observed in the M₂[Fe(CN)₆]–FeCl₃ or Fe₄[Fe(CN)₆]₃–MCl₂ systems under study. No electrophilic substitution Fe³⁺ Mn²⁺ was found to occur in any noticeable degree during the contact of Fe₄[Fe(CN)₆]₃ with aqueous MnCl₂ solutions even when this contact occurred for 1 h and longer.     

Pu3M和PuM3 (M=Ga,In, Sn,Ge)化合物的电子结构和形成热

采用全势线性缀加平面波(FPLAPW)方法, 在广义梯度近似(GGA)+自旋轨道耦合(SOC)+自旋极化(SP)下计算了具有AuCu3构型的Pu3M和PuM3 (M=Ga, In, Sn, Ge)化合物的平衡结构、电子结构和形成热. 计算的晶格常数与实验值符合得很好; 态密度分析表明Pu 和M 原子轨道间的杂化作用决定于Pu 6d-Pu 5f、Mp-Pu 6d和Msp-M sp轨道杂化之间的竞争, 而这种竞争又依赖于M的含量; 电负性差和电子杂化效应是影响Pu3M和PuM3化合物形成热和稳定性的两个重要因素, 电负性差越大, M的s、p带中心距费米能级越远, Pu3M(PuM3)化合物的形成热越负, 稳定性越高.     

杂硼原子簇XB6+ (X=C,Si, Ge,Sn, Pb)的稳定性和芳香性

利用从头算MP2方法和密度泛函理论B3LYP和B3PW91方法, 研究了杂硼原子簇XB₆⁺ (X=C, Si, Ge, Sn, Pb)的结构、稳定性及化学键合情况. 对C, Si, Ge, B使用6-311+G(d)基组, 对Sn和Pb使用LANL2DZ赝势基组. 研究结果表明, 具有C_s对称性的假平面XB₆⁺ (X=C, Si, Ge, Sn, Pb)结构是势能面上的全域极小点, 其稳定性要高于C_6v对称性的锥形结构和C₂对称性的假锥形结构. 在B3LYP水平上, 对这些异构体的势能面的极小点进行了自然键轨道(NBO)的分析; 对最稳定构型的最高占据分子轨道(HOMO)和最低空轨道(LUMO)能级差、分子轨道(MO)和核独立化学位移(NICS)进行了计算和讨论. 分析了杂原子和硼原子间、相邻硼原子间的键合情况, 讨论了最稳定构型的芳香性质.     

Synthesis,crystal structures,and properties of two heterometallic Cu(II)–M(II) (M = Zn,Ni) oxamidato-bridged coordination complexes

Two heterometallic coordination complexes, {[Cu(aeop)Zn(H₂O)₃]₂?·?3H₂O} _n (1) and [Cu(aeop)Ni(H₂O)₄]?·?4H₂O (2) (H₄aeop?=?N-(2-aminoterephthalic acid)-N′-(1,3-propanediamine)oxamidate), have been synthesized and characterized by elemental analyses, IR, UV spectroscopy, thermogravimetric analysis, and X-ray crystal diffraction. Complex 1 features a 1-D chain constructed from neutral tetranuclear units. Complex 2 is a neutral binuclear complex. Through intermolecular hydrogen-bonding interactions, 2 gives a 3-D network structure. The variable temperature magnetic susceptibility measurements (2–300?K) of 2 show a pronounced antiferromagnetic interaction between the copper(II) and nickel(II), and the exchange integral J is equal to ?42.7?cm^?1.     

The Insertion of EII and EIV Chlorides (E=Si,Ge) into the Si−Si Bond of Disilylene

Reactions of silicon and germanium dichlorides L ⋅ ECl₂ (E=Si, L=IPr; E=Ge, L=dioxane) with the phosphinoamidinato-supported disilylene ({κ²(N,P)-NNP}Si)₂ resulted in formal tetrylene insertions into the Si−Si bond. In the case of the reaction with silylene, two products were isolated. The first product ({κ²(N,P)-NNP}Si)₂SiCl₂, is the formal product of direct SiCl₂ insertion into the Si−Si bond of ({κ²(N,P)-NNP}Si)₂ and thus features two separated silylamido silylene centers. Over time, migration of the SiCl₂ group to a lateral position afforded the second product, the disilylene {κ²(Si,P)−SiCl₂NNP}Si−Si{κ²(N,P)-NNP}. In contrast, insertion of GeCl₂ resulted only in the isolation of the germanium analogue of {κ²(Si,P)−SiCl₂NNP}Si−Si{κ²(N,P)-NNP}, containing a Ge atom in the central position namely, compound {κ²(Si,P)−SiCl₂NNP}Ge−Si{κ²(N,P)-NNP}, which is a rare example of a silylene-germylene. Finally, reaction of disilylene ({κ²(N,P)−NNP}Si)₂ with SiCl₄ and SiHCl₃ led to the formation of the new bis(silyl)silylene, ({NNP}SiCl₂)₂Si:. All four new products from these insertion reactions have been characterized by multinuclear NMR and single-crystal X-ray diffraction studies.     

Electrophilic Substitution Ni(II)→M(II) in Ni2[Fe(CN)6] Gelatin-immobilized Matrix Materials

The electrophilic substitution reactions Ni(II)M(II) (M = Co, Cu, Zn, Cd) occurring in nickel(II) hexacyanoferrate(II) gelatin-immobilized matrix materials on their contact with aqueous solutions of corresponding chlorides MCl2 were studied. During contact, Ni(II) is partly substituted by the other metal to form heteronuclear hexacyanoferrates(II) of nickel(II) and corresponding double-charged ions, and none of the studied reactions involves complete substitution of Ni(II) until the mononuclear hexacyanoferrate(II) M₂[Fe(CN)₆] has formed.     

Solid Solutions of Grimm–Sommerfeld Analogous Nitride Semiconductors II-IV-N2 (II=Mg,Mn, Zn; IV=Si,Ge): Ammonothermal Synthesis and DFT Calculations

Grimm–Sommerfeld analogous II-IV-N₂ nitrides such as ZnSiN₂, ZnGeN₂, and MgGeN₂ are promising semiconductor materials for substitution of commonly used (Al,Ga,In)N. Herein, the ammonothermal synthesis of solid solutions of II-IV-N₂ compounds (II=Mg, Mn, Zn; IV=Si, Ge) having the general formula (II^a_1−xII^b_x)-IV-N₂ with x≈0.5 and ab initio DFT calculations of their electronic and optical properties are presented. The ammonothermal reactions were conducted in custom-built, high-temperature, high-pressure autoclaves by using the corresponding elements as starting materials. NaNH₂ and KNH₂ act as ammonobasic mineralizers that increase the solubility of the reactants in supercritical ammonia. Temperatures between 870 and 1070 K and pressures up to 200 MPa were chosen as reaction conditions. All solid solutions crystallize in wurtzite-type superstructures with space group Pna2₁ (no. 33), confirmed by powder XRD. The chemical compositions were analyzed by energy-dispersive X-ray spectroscopy. Diffuse reflectance spectroscopy was used for estimation of optical bandgaps of all compounds, which ranged from 2.6 to 3.5 eV (Ge compounds) and from 3.6 to 4.4 eV (Si compounds), and thus demonstrated bandgap tunability between the respective boundary phases. Experimental findings were corroborated by DFT calculations of the electronic structure of pseudorelaxed mixed-occupancy structures by using the KKR+CPA approach.