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21.
The Hydroalumination of 1,1,4,4‐Tetramethyl‐2,3‐diazabutadiene by Dialkylaluminium Hydrides – Synthesis of Dialkylaluminium Hydrazonides 1,1,4,4‐Tetramethyl‐2,3‐diazabutadiene reacted with dimethylaluminium hydride by hydroalumination of only one C=N double bond. The hydrazone derivative [Me2Al–N(CHMe2)–N=CMe2]2 ( 1 ) was formed which gave a dimer possessing a six‐membered Al2N4 heterocycle. The hydroalumination of both C=N double bonds was not observed. Also an excess of di(tert‐butyl)‐ or bis(trimethylsilylmethyl)aluminium hydride afforded only the product of a single hydroalumination step, a second dialkylaluminium hydride molecule was attached via a coordinative interaction between its central aluminium atom and the nitrogen atom of the C=N double bond and in addition via a 3 c‐2 e Al–H–Al bond. Compounds [(Me3C)2Al][(Me3C)2AlH]N(CHMe2)NCMe2 ( 2 ) and [(Me3SiCH2)2Al][(Me3SiCH2)2AlH]N(CHMe2)NCMe2 ( 3 ) were formed which have five‐membered Al2N2H heterocycles. Thermolysis of 2 gave by C–H activation compound [(Me3C)2Al]2[CH2C(Me)=N–]2 ( 4 ) in trace amounts which possesses two anellated AlN2C2 rings with a common N–N bond. In contrast, the thermal decomposition of 3 yielded by the cleavage of the N–N bond a dimeric dialkylaluminium methylideneamide ( 5 ) which has two intact C=N double bonds. Up to now our attempts to insert a C=N double bond into an Al–C bond remained unsuccessful, and only the formation of an adduct [(Me3C)3Al(–N=CMe2)2] ( 6 ) was observed upon treatment of tri(tert‐butyl)aluminium with the diazabutadiene derivative. 相似文献
22.
The room temperature deposition of PTCDA on hydrogen passivated Si(1 1 1), as a function of evaporation temperature and dosing time, has been studied by STM. At low evaporation temperature, 200 °C, clusters with an average size of 3.5 nm are formed on the surface. The mobility of the small clusters is so high, even at room temperature, that most of the clusters are trapped at surface defects. By increasing the evaporation temperature to 230 °C, larger clusters are formed which have lower mobility. The growth process is identified as a Volmer-Weber mechanism. On increasing the evaporation temperature further to 250 °C, crystals with dendritic shape are formed with an average size of 150 nm. The terraces of the crystal are formed with the (1 0 2) basal plane of the α-phase. Molecular resolution on the terrace also allows us to identify the molecular mechanism involved in the growth of the dendritic crystals. 相似文献
23.
Appearances and disappearances of Gd islands grown on top of a W(1 1 0) substrate were observed in time scales of hours after exposing the surface to a few Langmuirs of hydrogen. The phenomenon is presented and explained in terms of (temporary) creation of electrically floating islands, due to electrical decoupling of the island and substrate by the hydrogen that diffuses into the island/substrate interface. The disappearance of such an island is explained by forming a double barrier junction consisting of two tunneling barriers in series, causing, by charging, the potential of the island to become equal to that of the tip. The island then becomes “invisible” and the tip follows the corrugation of the surface under the substrate. The reappearance follows hydrogen mobility that retains the electrical conductivity of the island-substrate interface. 相似文献
24.
Natalia V. Belkova Elena S. Shubina Evgenii I. Gutsul Lina M. Epstein Igor L. Eremenko Sergei E. Nefedov 《Journal of organometallic chemistry》2000,610(1-2)
The interaction of rhenium hydrides ReHX(CO)(NO)(PR3)2 1 (X=H, R=Me (a), Et (b), iPr (c); X=Cl, R=Me (d)) with a series of proton donors (indole, phenols, fluorinated alcohols, trifluoroacetic acid) was studied by variable temperature IR spectroscopy. The conditions governing the hydrogen bonding ReHHX in solution and in the solid state (IR, X-ray) were elucidated. Spectroscopic and thermodynamic characteristics (−ΔH=2.3–6.1 kcal mol−1) of these hydrogen bonded complexes were obtained. IR spectral evidence that hydrogen bonding with hydride atom precedes proton transfer and the dihydrogen complex formation was found. Hydrogen bonded complex of ReH2(CO)(NO)(PMe3)2 with indole (2a–indole) and organyloxy-complex ReH(OC6H4NO2)(CO)(NO)(PMe3)2 (5a) were characterized by single-crystal X-ray diffraction. A short NHHRe (1.79(5) Å) distance was found in the 2a–indole complex, where the indole molecule lies in the plane of the Re(NO)(CO) fragment (with dihedral angle between the planes 0.01°). 相似文献
25.
DFT methods have been applied for the calculation of several ground-state properties of neutral and charged ruthenium(II) and osmium(II) tin trihydride complexes bearing N-donor, P-donor and C-donor ancillary ligands in their coordination sphere. Complexes of the type M(SnH3)(Tp)(PPh3)P(OMe)3, M(SnH3)(Cp)(PPh3)P(OMe)3 and [M(SnH3)(Bpy)2P(OMe)3]+ (M = Ru, Os; Tp = tris(pyrazol-1-yl)borate; Cp = cyclopentadienyl ion; Bpy = 2,2′-bipyridine) have been studied using the EDF2 and B3PW91 functionals. The same calculations have been carried out also on the corresponding [M]-CH3 and [M]-H compounds, to compare the electronic features of the different reactive ligands coordinated to the same metal fragments. Charge distribution analyses were used to give insight into the roles of the transition metal centres and the ancillary ligands on the properties of the coordinated SnH3 group. The molecular orbitals of the methyl- and trihydrostannyl-complexes were compared to understand the nature of the [M]-SnH3 bond and the electronic transitions of these species. 相似文献
26.
氢化物发生的碱性模式 总被引:30,自引:0,他引:30
氢化物发生除了可由氢化元素的酸性溶液与NaBH4作用的传统反应模式外,还可通过含有NaBH4的氢化元素碱性溶液为作用“碱性反应模式”来完成,碱性模式所发生的氢化物的产率与传统模式的产率相同或相近。碱性反应模式氢化物发生法避免Ⅷ族过渡金属及铜分族金属的严重化学干扰。 相似文献
27.
Yuntao Wang Huaiyu Shao Xingguo Li Lefu Zhang Seiki Takahashi 《Journal of magnetism and magnetic materials》2006
Magnetic properties of SmFeAl and its hydrides synthesized at 298–673 K under 40 bar hydrogen pressure were investigated by a superconducting quantum interference device (SQUID) from 4.2 to 300 K. SmFeAl and its hydrides have a mictomagnetic transition during the field-cooled process. In both SmFeAl and its hydrides, a shifted magnetic hysteresis cycle towards positive magnetization was observed. But when SmFeAlHx decomposes completely into SmHx and Fe–Al alloy, this special transition disappears. 相似文献
28.
We present a comprehensive vibrational study of the clean and hydrogen- or deuterium-terminated silicon (0 0 1) surface. The modes related to the clean as well as to the H:Si, D:Si, and 2H:Si, 2D:Si surfaces are studied by means of high resolution electron energy loss spectroscopy (HREELS). We pay special attention to the modification of the phonon modes by the surface treatments and compare the data with reported experimental and theoretical results. The analysis of the relative phonon intensities of the clean, mono- and dihydride surfaces yields the assignment of the modes related to the dimer bonds. The isotopic shifts of vibrons related to the Si-H and Si-D bonds and to the surface phonon are discussed and applied to the characterisation of the surface excitations. 相似文献
29.
The lithium bis(amido)hydridooxidoaluminate cluster [{Li(C14H30N2)AlHO1/2}4] has been synthesized during systematic metallation/hydrometallation studies of a series of 1,4‐diazabut‐1‐enes with lithium aluminiumhydride. Formation of the complex is presumably derived from partial hydrolysis of the related lithium bis(amido)dihydridoaluminate and has been characterized using single crystal X‐ray diffraction. The complex crystallizes in the monoclinic space group C2/c (No. 15) with a = 25.012(2) Å, b = 10.673(2) Å, c = 28.673(3) Å, β = 115.855(7)°, V = 6887(1) Å3, Z = 4. The complex exhibits an oligomeric structure of crystallographic C2 symmetry, comprised of complex multicyclic units arising from extensive metal, hydride, oxide and ligand bridging interactions. These associations give rise to edge‐fused, non‐planar NAlOLi four‐membered rings tightly binding two of the diamido‐chelated aluminate units, with these in turn aggregating further via two of the μ2‐hydrides involving lithium atoms. 相似文献
30.
Sophia L. Wandelt Dr. Alexander Mutschke Dr. Dmitry Khalyavin Robert Calaminus Jennifer Steinadler Prof. Dr. Bettina V. Lotsch Prof. Dr. Wolfgang Schnick 《Angewandte Chemie (International ed. in English)》2023,62(50):e202313564
Multianionic metal hydrides, which exhibit a wide variety of physical properties and complex structures, have recently attracted growing interest. Here we present Sr6N[BN2]2H3, prepared in a solid-state ampoule reaction at 800 °C, as the first combination of nitridoborate, nitride and hydride anions within a single compound. The crystal structure was solved from single-crystal X-ray and neutron powder diffraction data in space group P21/c (no. 14), revealing a three-dimensional network of undulated layers of nitridoborate units, strontium atoms and hydride together with nitride anions. Magic angle spinning (MAS) NMR and vibrational spectroscopy in combination with quantum chemical calculations further confirm the structure model. Electrochemical measurements suggest the existence of hydride ion conductivity, allowing the hydrides to migrate along the layers. 相似文献