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101.
The formula of a new compound isolated in the LaOsO system has been established by means of crystal structure determination. There are two La3Os2O10 units in a face-centered monoclinic unit cell (S.G. ); a = 7.911(2) Å, b = 7.963(2) Å, c = 6.966(2)Å, β = 115.76(2)°;. For 1082 intensities, collected on an automated single-crystal diffractometer, the final R value was 0.025 after absorption corrections. The structure consists of isolated Os2O10 clusters composed of two edge-shared OsO6 octahedra. These dimeric units are connected together by two types of La3+ ions in eightfold coordination. In view of the OsOs distance inside the pair (2.462 Å), La3Os2O10 provides an example of metal-metal bonding involving a transition metal in a half-integral formal oxidation state of 5.5. 相似文献
102.
Dessapt R Simonnet-Jégat C Mallard A Lavanant H Marrot J Sécheresse F 《Inorganic chemistry》2003,42(20):6425-6431
Three new Mo(V) dithiolene compounds have been synthesized by addition of alkynes ((Me(3)Si)(2)C(2) (TMSA), (Me(3)Si)(2)C(4), and (Ph)(2)C(4) to MoO(2)S(2)(2-) in a MeOH/NH(3) mixture: [Mo(2)(O)(2)(mu-S)(2)(eta(2)-S(2))(eta(2)-S(2)C(2)H(2))](2)(-) 1, [Mo(2)(O)(X)(mu-S)(2)(eta(2)-S(2))(eta(2)-S(2)C(2)Ph(C(2)Ph))](2-) 2 (X = O or S), and [Mo(2)(O)(2)(mu-S)(2)(eta(2)-S(2))(eta(2)-S(2)C(2)H(C(2)H))](2-) 3. The structure of 1 as determined by single-crystal X-ray diffraction study (space group Pbca, a = 13.3148(1) A, b = 15.7467(4) A, c = 28.4108(7) A, V = 5956.7(2) A(3)) is discussed. 2 and 3 have been identified by ESMS (electrospray mass spectrometry), (1)H NMR, (13)C NMR, and infrared spectroscopies. This investigation completes our previous study devoted to the addition of DPA (C(2)Ph(2)) to MoO(2)S(2)(2-) which led to [Mo(2)(O)(X)(mu-S)(2)(eta(2)-S(2))(eta(2)-S(2)C(2)Ph(2))](2-) 4 (X = O or S). A reaction scheme is proposed to explain the formation of the different species present in solution. The reactivity of the remaining nucleophilic site of these complexes (eta(2)-S(2)) toward dicarbomethoxyacetylene (DMA) is also discussed. 相似文献
103.
Sai Kumar Chakka Zamani E.D. Cele Sphelele C. Sosibo Vivian Francis Per I. Arvidsson Hendrik G. Kruger Glenn E.M. Maguire Thavendran Govender 《Tetrahedron: Asymmetry》2012,23(8):616-622
A series of novel TIQ based N,N′-oxide ligands were synthesised and screened for their catalytic activity in the enantioselective conjugate addition of thioglycolate to chalcones. Bulky groups on the side chain of the TIQ backbone provided the highest enantioselectivity of up to 88% with 10 mol % catalyst loading. It was also observed that these reactions proceeded optimally in the presence of dichloromethane as a solvent. Screening of various metals emphasized La(OTf)3 as the ideal pre-catalyst for this particular reaction. 相似文献
104.
105.
106.
Francis E. Burstall Udo Hertrich-Jeromin Wayne Rossman 《Comptes Rendus Mathematique》2012,350(7-8):413-416
We show how linear Weingarten surfaces appear as special Ω-surfaces and give a characterization of those linear Weingarten surfaces that allow a Weierstrass type representation. 相似文献
107.
Bijesh Sekaran Youngwoo Jang Prof. Dr. Rajneesh Misra Prof. Dr. Francis D'Souza 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(56):12991-13001
A new set of free-base and zinc(II)-metallated, β-pyrrole-functionalized unsymmetrical push–pull porphyrins were designed and synthesized via β-mono- and dibrominated tetraphenylporphyrins using Sonogashira cross-coupling reactions. The ability of donors and acceptors on the push–pull porphyrins to produce high-potential charge separated states was investigated. The porphyrins were functionalized at the opposite β,β′-pyrrole positions of porphyrin ring bearing triphenylamine push groups and naphthalimide pull groups. Systematic studies involving optical absorption, steady-state and time-resolved emission revealed existence of intramolecular type interactions both in the ground and excited states. The push–pull nature of the molecular systems was supported by frontier orbitals generated on optimized structures, wherein delocalization of HOMO over the push group and LUMO over the pull group connecting the porphyrin π-system was witnessed. Electrochemical studies were performed to visualize the effect of push and pull groups on the overall redox potentials of the porphyrins. Spectroelectrochemical studies combined with frontier orbitals helped in characterizing the one-electron oxidized and reduced porphyrins. Finally, by performing transient absorption studies in polar benzonitrile, the ability of push–pull porphyrins to produce charge-separated states upon photoexcitation was confirmed and the measured rates were in the range of 109 s−1. The lifetime of the final charge separated state was around 5 ns. This study ascertains the importance of push–pull porphyrins in solar energy conversion and diverse optoelectronic applications, for which high-potential charge-separated states are warranted. 相似文献
108.
Farah Naz Bibimaryam Mousavi Zhixiong Luo Christia Jabbour Philippe M. Heynderickx Somboon Chaemchuen Francis Verpoort 《应用有机金属化学》2019,33(5)
A series of spray dried zeolitic imidazolate frameworks (ZIFs = ZIF‐8, ZIF‐67, and Zn/Co‐ZIF) are used as a catalyst for the bulk ring‐opening polymerization of δ‐valerolactone without any co‐catalyst to generate polyvalerolactone. Interestingly, using the same catalyst under the same reaction conditions could manipulate the structure of the product polymer, and thus its physical properties. Thus, using a dried substrate leads to the formation of the cyclic polymer while a linear polymer was formed on using the commercially available substrate. An activated monomer mechanism has been suggested where the propagating zinc alkoxide undergoes an intramolecular transesterification to release cyclic or linear polyvalerolactone. The ROP of δ‐VL without drying shows that the polymeric zwitterions have little tendency to cyclize in the presence of moisture. At 140 °C, ZIF‐8 shows a superior catalytic activity resulting in the production of cyclic polyvalerolactone having a high molecular weight as compared to ZIF‐67 or Zn/Co‐ZIF due to the presence of highly active sites. The catalyst could be recycled and reused without any significant loss of catalytic activity. 相似文献
109.
THE REACTIONS OF N3P3CL6 AND RELATED COMPOUNDS WITH DIFUNCTIONAL REAGENTS. COMPARISONS AND CONTRASTS
Abdulla H. Alkubaisi W. Francis Deutsch Michael B. Hursthouse Harold G. Parkes Leylacaron S. Shaw Robert A. Shaw 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):229-237
Abstract The reactions of N3P3Cl6 with a variety of difunctional reagents are discussed. NMR spectroscopic and X-ray crystallographic investigations are presented. 相似文献
110.
Saeed Kamali Hongxin Wang Devrani Mitra Hideaki Ogata Wolfgang Lubitz Brian C. Manor Thomas B. Rauchfuss Deborah Byrne Violaine Bonnefoy Francis E. Jenney Michael W. W. Adams Yoshitaka Yoda Ercan Alp Jiyong Zhao Stephen P. Cramer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(2):752-756