Incorporation of quadruply-bonded units into solid-state materials

The thirtieth anniversary of the quadruple bond marks a time in science when synthetic inorganic chemists are exploring molecular routes to new solid-state materials. Dinuclear transition metal complexes possessing , , and components to their M-M bonding present exciting opportunities for the design of macromolecular compounds with interesting optical, electronic, and magnetic properties. This brief review reports recent progress in the area of ordered molecular arrays incorporating quadruply bonded and other multiply bonded M₂ units.     

烷基锂分子中化学键的 ab initio 研究

本文用6-13G基函对3-12G基优化构型进行单点ab initio (从头计算法) 计算, 并根据轨道的组合系数、电荷密度图和键强参数等详尽地分析了烷基锂分子的成键情况。烷基锂的易挥发、易聚合、聚合物易溶于烃类溶剂中等物理、化学性质主要是其C－Li键具有显著的共价性缘故。由于烷基锂的C-Li键比C－H和C－C键的强度要小,故C-Li键易于断裂,使烷基锂表现有高的化学反应活性。     

ⅥB族金属叁键有机化合物的研究进展

本文对一类重要的ⅥB族金属叁键化合物R_2M_2(CO)_4(R为环戊二烯基及类环戊二烯基)近年来的研究成果进行了综述,综述重点是这类化合物的官能团M≡M参键的化学活性,全文包括R_2M_2(CO)_4的合成及结构,M≡M叁键与亲核试剂、与碳-碳重键,与氧或与金属羰基物等试剂的反应及其应用。     

植物油的质谱分析：1.蓖麻油

运用一种植物油的系统分析方法测定蓖麻油的精细组分，这包括皂化，ＢＦ３－ＭｅＯＨ甲基化，ＧＣ－ＣＩＭＳ法测定脂肪酸碳链长度和不饱和度，ＡＭＰ衍生化，ＧＣ－ＥＩＭＳ测定不饱和脂肪酸的双链位置，分析了蓖麻油的十一种脂肪酸组分，有五个为未知组分，并测定了其中三个组分的双链位置。     

Bonding of the chain structure for novel boranes B3k+pH−5k+p+3

The molecular orbitals obtained from conventional quantum chemistry calculations, are expressed in terms of symmetrized valence bond functions of fragment, and a direct picture of chemical bonding can be drawn easily. This method is utilized, together with extended Huckel calculations, to interpret the bonding properties of a centipede-like chain structure for novel laser-producing boranes B_3k+pH^?_5k+p+3 which is constructed from the repeated unit B₃H₅ halted to each other by three B—H—B bonds.     

Synthesis and structures of new 1,3,6,2-dioxazaborocanes containing substituents in the ocane fragment

New 1,3,6,2-dioxazaborocanes R¹N(CHR³CR⁴R²O)(CHR⁶CHR⁵O)BX (1–11, X = Ph, 4-MeC₆H₄, Me; R¹ = Me, PhCH₂; R², R³, R⁴, R⁵, R⁶ = H, Ph) were synthesized by the reactions of aryl- or methylboronic acids with dialkanolamines. The treatment of (Me₂NCH₂CH₂O)₃B (15) with MeN(CH₂CH₂OH)(CH₂CPh₂OH) afforded 2-[2-(dime-thylamino)ethoxy]-1,3,6,2-dioxazaborocane (12). 2-Fluoro-1,3,6,2-dioxazaborocanes R¹N(CHR³CHR²O)(CH₂CH₂O)BF (13: R¹ = PhCH₂, R² = R³ = H; 14: R¹ = Me, R² = R³ = Ph, threo) were synthesized by the reaction of bis(trimethylsilyl) ethers of the corresponding dialkanolamines with BF₃·Et₂O. The new borocanes can be used for the synthesis of the corre-sponding germanium derivatives PhCH₂N(CH₂CH₂O)₂GeX₂ (16, X = OEt; 17, X = Cl), as exemplified by the reaction of compound 6. The structures of erythro-MeN(CH₂CH₂O)(CHPhCHPhO)BPh (3), threo-MeN(CH₂CH₂O)(CHPhCHPhO)BPh (4), erythro-MeN(CH₂CH₂O)(CHPhCHPhO)B(4-MeC₆H₄) (8), and PhCH₂N(CH₂CH₂O)₂BF (13) were established by X-ray diffraction. The coordination polyhedra of the boron atoms in these complexes can be described as distorted tetrahedra. The boron-nitrogen distances (1.705(7)–1.723(3) Å) provide unambiguous evidence for the presence of the B←N transannular interaction in these compounds. The structures of the resulting borocanes containing phenyl substituents at the carbon atoms of the ocane skeleton were studied by NMR spectroscopy and quantum chemical density functional theory calculations.     

Wavelength dependence of matrix-assisted laser desorption and ionization using a tunable mid-infrared laser

Matrix-assisted laser desorption and ionization by infrared laser (IR-MALDI) is expected to be an effective methods for soft-ionization of high-molecular weight proteins and intracellular proteins. IR-MALDI is not widely used because its low sensitivity, complexity, high cost, and as it does not work well on commercial MALDI time-of-flight mass spectrometers (TOFMSs). We employed a tunable mid-infrared (MIR) laser as a light source for MALDI to investigate the IR-MALDI. The laser wavelength can be tuned within a range from 5.5 to 10.0 μm, and included several biomaterial group vibration modes. We evaluated the wavelength dependence of ionization in IR-MALDI for four matrices: succinic acid, urea, 3,5-dimethoxy-4-hydroxycinnamic acid (sinapic acid) and 2,5-dihydroxybenzoic acid (DHB). These matrices contained various groups of vibration modes, and absorbed an infrared (IR) energy at a specific wavelength. The mass spectra of angiotensin II was obtained at a specific wavelength corresponding to the CO stretching and benzene ring vibration mode. In IR-MALDI, we considered the strong molecular bond attracting an electron from a neighboring hydrogen atom, possibly protonating the hydrogen atom.     

Synthesis, structure, and reactivity of a pyridine-stabilized germanone

The first isolable pyridine‐stabilized germanone has been prepared and its reactivity toward trimethylaluminum has been investigated. The germanone adduct results from a stepwise conversion that starts from 4‐dimethylaminopyridine (DMAP) and the ylide‐like N‐heterocyclic germylene LGe: (L=CH{(C?CH₂)(CMe)[N(aryl)]₂}, aryl=2,6‐iPr₂C₆H₃) ( 1 ) at room temperature, and gives the corresponding germylene–pyridine adduct L(DMAP)Ge: ( 2 ) in 91 % yield. The latter reacts with N₂O at room temperature to form the desired germanone complex L(DMAP)Ge?O ( 3 ) in 73 % yield. The Ge? O distance of 1.646(2) Å in 3 is the shortest hitherto reported for a Ge?O species. The reaction of 3 with trimethylaluminum leads solely to the addition product LGe(Me)O[Al(DMAP)Me₂] ( 4 ). The latter results from insertion of the Ge?O subunit into an Al? Me bond of AlMe₃ and concomitant migration of the DMAP ligand from germanium to the aluminum atom. Compounds 2 – 4 have been fully characterized by analytical and spectroscopic methods. Their molecular structures have been established by single‐crystal X‐ray crystallographic analysis.