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1.
Alexander S. Novikov Dr. Maxim L. Kuznetsov Prof. Armando J. L. Pombeiro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(8):2874-2888
The theoretical background of the formation of N‐heterocyclic oxadiazoline carbenes through a metal‐assisted [2+3]‐dipolar cycloaddition (CA) reaction of nitrones R1CH?N(R2)O to isocyanides C?NR and the decomposition of these carbenes to imines R1CH?NR2 and isocyanates O?C?NR is discussed. Furthermore, the reaction mechanisms and factors that govern these processes are analyzed in detail. In the absence of a metal, oxadiazoline carbenes should not be accessible due to the high activation energy of their formation and their low thermodynamic stability. The most efficient promotors that could assist the synthesis of these species should be “carbenophilic” metals that form a strong bond with the oxadiazoline heterocycle, but without significant involvement of π‐back donation, namely, AuI, AuIII, PtII, PtIV, ReV, and PdII metal centers. These metals, on the one hand, significantly facilitate the coupling of nitrones with isocyanides and, on the other hand, stabilize the derived carbene heterocycles toward decomposition. The energy of the LUMOCNR and the charge on the N atom of the C?N group are principal factors that control the cycloaddition of nitrones to isocyanides. The alkyl‐substituted nitrones and isocyanides are predicted to be more active in the CA reaction than the aryl‐substituted species, and the N,N,C‐alkyloxadiazolines are more stable toward decomposition relative to the aryl derivatives. 相似文献
2.
The formal 1,3‐cycloaddition of 2‐diazocyclohexane‐1,3‐diones 1a –1 d to acyclic and cyclic enol ethers in the presence of RhII‐catalysts to afford dihydrofurans has been investigated. Reaction with a cis/trans mixture of 1‐ethoxyprop‐1‐ene ( 13a ) yielded the dihydrofuran 14a with a cis/trans ratio of 85 : 15, while that with (Z)‐1‐ethoxy‐3,3,3‐trifluoroprop‐1‐ene ( 13b ) gave the cis‐product 14b exclusively. The stereochemical outcome of the reaction is consistent with a concerted rather than stepwise mechanism for cycloaddition. The asymmetric cycloaddition of 2‐diazocyclohexane‐1,3‐dione ( 1a ) or 2‐diazodimedone (=2‐diazo‐5,5‐dimethylcyclohexane‐1,3‐dione; 1b ) to furan and dihydrofuran was investigated with a representative selection of chiral, nonracemic RhII catalysts, but no significant enantioselectivity was observed, and the reported enantioselective cycloadditions of these diazo compounds could not be reproduced. The absence of enantioselectivity in the cycloadditions of 2‐diazocyclohexane‐1,3‐diones is tentatively explained in terms of the Hammond postulate. The transition state for the cycloaddition occurs early on the reaction coordinate owing to the high reactivity of the intermediate metallocarbene. An early transition state is associated with low selectivity. In contrast, the transition state for transfer of stabilized metallocarbenes occurs later, and the reactions exhibit higher selectivity. 相似文献
3.
The 1,3‐dipolar cycloaddition reactions of 2‐diazocyclohexane‐1,3‐dione ( 7a ; Table 1) and of alkyl diazopyruvates ( 11a – e ; Table 3) to 2,3‐dihydrofuran and other enol ethers have been investigated in the presence of chiral transition metal catalysts. With RhII catalysts, the cycloadditions were not enantioselective, but those catalyzed by [RuIICl2( 1a )] and [RuIICl2( 1b )] proceeded with enantioselectivities of up to 58% and 74% ee, respectively, when diazopyruvates 11 were used as substrates. The phenyliodonium ylide 7c yielded the adduct 8a in lower yield and poorer selectivity than the corresponding diazo precursor 7a (Table 2) upon decomposition with [Ru(pybox)] catalysts. This suggests that ylide decomposition by RuII catalysts, contrary to that of the corresponding diazo precursors, does not lead to Ru‐carbene complexes as reactive intermediates. Our method represents the first reproducible, enantioselective 1,3‐cycloaddition of these types of substrates. 相似文献
4.
Dr. Pascal Roy Andreas Schaate Prof. Dr. Peter Behrens Prof. Dr. Adelheid Godt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(22):6979-6985
Cycloaddition reactions are highly attractive for post‐synthetic modification of metal–organic frameworks (MOFs). We report herein on cycloaddition reactions with PIZOF(R1,R2)s, which are porous interpenetrated Zr‐based MOFs with Zr6O4(OH)4(CO2)12 as the nodes and the dicarboxylates ?O2C[PE‐P(R1,R2)‐EP]CO2? (P: phenylene, E: ethynylene; R1, R2: side chains at the central phenylene unit) as the linkers. 1,3‐Dipolar cycloaddition between the pendant ethyne moieties of PIZOF(OMe,OCH2C?CH) and 4‐methylbenzyl azide resulted in 98 % conversion of the ethyne groups. Reactions of PIZOF(OMe,O(CH2)3furan) with maleimide, N‐methylmaleimide, and N‐phenylmaleimide converted 98, 99, and 89 % of the furan moieties into the Diels–Alder adducts. However, no reaction occurred with maleic anhydride. High‐resolution 1H NMR spectra were crucial in determining the conversion and identifying the reaction products. Of all the reagents (NaOD/D2O, D2SO4, Bu4NF, CsF, CsF/DCl, and KHF2) tested for the disassembly of the PIZOFs in [D6]DMSO, the combination of CsF and DCl was found to be the best. The disassembly at room temperature was fast (5–15 min), and after the addition of K2CO3 the 1H NMR data were identical to those of the diacids (=protonated linkers) dissolved in pure DMSO. This allowed for simple structure elucidation through data comparison. CsF/DCl dissolves not only PIZOFs but also the hydrolytically very stable UiO‐66. 相似文献
5.
Active space and basis set effects in CASPT2 models of the 1,3‐butadiene‐ethene cycloaddition and the 1,3‐butadiene dimerization
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David L. A. Scarborough Rika Kobayashi Christopher D. Thompson Ekaterina I. Izgorodina 《International journal of quantum chemistry》2015,115(15):989-1001
The first step of the asynchronous biradical, stepwise biradical, and concerted mechanisms of the 1,3‐butadiene Diels–Alder reactions with both ethene and itself was studied using CASPT2 to determine the influence of basis set and active space on reaction barriers. CASPT2(6,6) with the cc‐pVDZ, 6‐311+G(3df,2p) and cc‐pVTZ basis sets provided the best results with average errors below 3.1 kJ mol?1 with respect to the experimental result. Increasing the active space size also had little effect on the calculated reaction barriers. With respect to experimental results, uncontracted multireference averaged quadratic coupled cluster (MRAQCC) produced superior barriers than internally contracted MRAQCC by 16.1–39.3 kJ mol?1. The inability of CASSCF to locate transition states for some of the cycloadditions across the butadiene‐ethene and butadiene dimerization reactions is also rationalized. CASPT2 suggests a preference for the concerted mechanism of the butadiene‐ethene reaction, however, no basis set yielded a preference for any of the butadiene dimerization pathways. © 2015 Wiley Periodicals, Inc. 相似文献
6.
Alban Falconnet Marc Magre Bholanath Maity Luigi Cavallo Magnus Rueping 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17731-17735
Asymmetric catalysis with readily available, cheap, and non‐toxic alkaline earth metal catalysts represents a sustainable alternative to conventional synthesis methodologies. In this context, we describe the development of a first MgII‐catalyzed enantioselective hydroboration providing the products with excellent yields and enantioselectivities. NMR spectroscopy studies and DFT calculations provide insights into the reaction mechanism and the origin of the enantioselectivity which can be explained by a metal‐ligand cooperative catalysis pathway involving a non‐innocent ligand. 相似文献
7.
CaII Binding Regulates and Dominates the Reactivity of a Transition‐Metal‐Ion‐Dependent Diesterase from Mycobacterium tuberculosis
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Dr. Marcelo M. Pedroso Prof. James A. Larrabee Dr. Fernanda Ely Shuhui E. Gwee Dr. Nataša Mitić Prof. David L. Ollis Prof. Lawrence R. Gahan Prof. Gerhard Schenk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):999-1009
The diesterase Rv0805 from Mycobacterium tuberculosis is a dinuclear metallohydrolase that plays an important role in signal transduction by controlling the intracellular levels of cyclic nucleotides. As Rv0805 is essential for mycobacterial growth it is a promising new target for the development of chemotherapeutics to treat tuberculosis. The in vivo metal‐ion composition of Rv0805 is subject to debate. Here, we demonstrate that the active site accommodates two divalent transition metal ions with binding affinities ranging from approximately 50 nm for MnII to about 600 nm for ZnII. In contrast, the enzyme GpdQ from Enterobacter aerogenes, despite having a coordination sphere identical to that of Rv0805, binds only one metal ion in the absence of substrate, thus demonstrating the significance of the outer sphere to modulate metal‐ion binding and enzymatic reactivity. CaII also binds tightly to Rv0805 (Kd≈40 nm ), but kinetic, calorimetric, and spectroscopic data indicate that two CaII ions bind at a site different from the dinuclear transition‐metal‐ion binding site. CaII acts as an activator of the enzymatic activity but is able to promote the hydrolysis of substrates even in the absence of transition‐metal ions, thus providing an effective strategy for the regulation of the enzymatic activity. 相似文献
8.
Benjamin W. Gung Prof. Dr. Derek T. Craft Lauren N. Bailey Kristin Kirschbaum Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(2):639-644
Macrocyclic propargyl acetates containing a furan ring were prepared by using a CrCl2‐promoted reaction. In the presence of either a AuI or AuIII catalyst, a tandem 3,3‐rearrangement/transannular [4+3] cycloaddition reaction occurred to give propargyl acetates that are regio‐ and diastereospecific. The regiochemistry of the product is controlled by the position of the acetoxy group in the starting material and the stereochemistry of the reaction depends on the ring size. 相似文献
9.
Dr. Jakub Šebera Prof. Jaroslav Burda Dr. Michal Straka Prof. Akira Ono Prof. Chojiro Kojima Prof. Yoshiyuki Tanaka Dr. Vladimír Sychrovský 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(30):9884-9894
A reaction mechanism that describes the substitution of two imino protons in a thymine:thymine (T:T) mismatched DNA base pair with a HgII ion, which results in the formation of a (T)N3‐HgII‐N3(T) metal‐mediated base pair was proposed and calculated. The mechanism assumes two key steps: The formation of the first HgII? N3(T) bond is triggered by deprotonation of the imino N3 atom in thymine with a hydroxo ligand on the HgII ion. The formation of the second HgII? N3(T) bond proceeds through water‐assisted tautomerization of the remaining, metal‐nonbonded thymine base or through thymine deprotonation with a hydroxo ligand of the HgII ion already coordinated to the thymine base. The thermodynamic parameters ΔGR=?9.5 kcal mol?1, ΔHR=?4.7 kcal mol?1, and ΔSR=16.0 cal mol?1 K?1 calculated with the ONIOM (B3LYP:BP86) method for the reaction agreed well with the isothermal titration calorimetric (ITC) measurements by Torigoe et al. [H. Torigoe, A. Ono, T. Kozasa, Chem. Eur. J. 2010 , 16, 13218–13225]. The peculiar positive reaction entropy measured previously was due to both dehydration of the metal and the change in chemical bonding. The mercury reactant in the theoretical model contained one hydroxo ligand in accord with the experimental pKa value of 3.6 known for an aqua ligand of a HgII center. The chemical modification of T:T mismatched to the T‐HgII‐T metal‐mediated base pair was modeled for the middle base pair within a trinucleotide B‐DNA duplex, which ensured complete dehydration of the HgII ion during the reaction. 相似文献
10.
Olefin Cyclopropanation by Radical Carbene Transfer Reactions Promoted by Cobalt(II)/Porphyrinates: Active‐Metal‐Template Synthesis of [2]Rotaxanes
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Arthur F. P. Alcântara Liniquer A. Fontana Vitor H. Rigolin Yuri F. S. Andrade Dr. Marcos A. Ribeiro Prof. Wdeson P. Barros Prof. Catia Ornelas Prof. Jackson D. Megiatto Jr. 《Angewandte Chemie (International ed. in English)》2018,57(29):8979-8983
A CoII/porphyrinate‐based macrocycle in the presence of a 3,5‐diphenylpyridine axial ligand functions as an endotopic ligand to direct the assembly of [2]rotaxanes from diazo and styrene half‐threads, by radical‐carbene‐transfer reactions, in excellent 95 % yield. The method reported herein applies the active‐metal‐template strategy to include radical‐type activation of ligands by the metal‐template ion during the organometallic process which ultimately yields the mechanical bond. A careful quantitative analysis of the product distribution afforded from the rotaxane self‐assembly reaction shows that the CoII/porphyrinate subunit is still active after formation of the mechanical bond and, upon coordination of an additional diazo half‐thread derivative, promotes a novel intercomponent C?H insertion reaction to yield a new rotaxane‐like species. This unexpected intercomponent C?H insertion illustrates the distinct reactivity brought to the CoII/porphyrinate catalyst by the mechanical bond. 相似文献
11.
Ryan C. Conyers Prof. Dr. Benjamin W. Gung 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):654-664
With the use of benzonitrile‐stabilized AuI catalyst [Au(IPr)(NCPh)]SbF6 ( Ic ; IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene), a spectrum of reactivity is observed for propargyl ester 4 a with cyclic vinyl ethers, ranging from exclusively [3C+2C] cycloaddition reactions to exclusively cyclopropanation depending only on the structure of the substrate. Some initially formed cyclopropanation products rearrange into the corresponding formally [3C+2C] cycloaddition products after treatment with fresh AuI complex at 80 °C. Vinylcyclopropanes formed from dihydrofuran and dihydropyran resisted such rearrangement, even in the presence of fresh AuI catalyst at elevated temperature. This study addresses an important mechanistic question concerning whether the five‐membered‐ring products were produced by a direct [3C+2C] cycloaddition reaction or by a sequential cyclopropanation/ring‐expansion reaction. A dual pathway is proposed for the AuI‐catalyzed reactions between propargyl esters and cyclic vinyl ethers. The different behavior among vinyl cyclic ethers is attributed to the difference in the polarization of the π bond. Highly polarized bonds appear to undergo the cycloaddition reaction whereas less polar π‐bonds produce cyclopropanes. 相似文献
12.
Prof. Dr. Holger Braunschweig Dr. William C. Ewing Thomas Kramer James D. Mattock Dr. Alfredo Vargas Christine Werner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(35):12347-12356
A number of trimetalloborides have been synthesized through the reactions of base‐stabilized coinage metal chlorides with a dimanganaborylene lithium salt in the hope of using this organometallic platform to compare and evaluate the electronics of these popular coinage metal fragments. The adducts of CuI, AgI, and AuI ions, stabilized by tricyclohexylphosphine (PCy3), N‐1,3‐bis(4‐methylphenyl)imidazol‐2‐ylidene (ITol), or 1‐(2,6‐diisopropylphenyl)‐3,3,5,5‐tetramethylpyrrolidin‐2‐ylidene (CAAC), with [{Cp(CO)2Mn}2B]? were studied spectroscopically, structurally, and computationally. The geometries of the adducts fall into two classes, one symmetric and one asymmetric, each relying on the combined characteristics of both the metal and ligand. The energetic factors proposed as the causes of the structural differences were investigated by ETS‐NOCV (extended transition state‐natural orbitals for chemical valence) analysis, which showed the final geometry to be controlled by the competition between the tendency of the coinage metal to adopt a higher or lower coordination number and the willingness of the cationic fragment to participate in back‐bonding interactions. 相似文献
13.
Divergent Synthesis of CF3‐Substituted Allenyl Nitriles by Ligand‐Controlled Radical 1,2‐ and 1,4‐Addition to 1,3‐Enynes
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Fei Wang Dinghai Wang Yu Zhou Ling Liang Ronghua Lu Dr. Pinhong Chen Prof. Dr. Zhenyang Lin Prof. Dr. Guosheng Liu 《Angewandte Chemie (International ed. in English)》2018,57(24):7140-7145
A ligand‐controlled system that enables regioselective trifluoromethylcyanation of 1,3‐enynes has been identified, which provides access to a variety of CF3‐containing tri‐ and tetrasubstituted allenyl nitriles. We disclose that the involved propargylic radicals can be selectively trapped by (Box)CuII cyanide, while the tautomerized allenyl radicals are trapped by (phen)CuII cyanide (Box= bisoxazoline, phen=phenanthroline). In addition, the reaction features broad substrate scope and excellent functional group compatibility. Moreover, this protocol represents a novel regioselectivity‐tunable functionalization of 1,3‐enynes via radicals, which we believe will have great implications for the development of catalytic systems for selectivity control in radical and organometallic chemistry. 相似文献
14.
Synthesis,Structures, and Properties of Crystalline Salts with Radical Anions of Metal‐Containing and Metal‐Free Phthalocyanines
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Dr. Dmitri V. Konarev Dr. Alexey V. Kuzmin Dr. Maxim A. Faraonov Dr. Manabu Ishikawa Dr. Salavat S. Khasanov Dr. Yoshiaki Nakano Dr. Akihiro Otsuka Prof. Hideki Yamochi Prof. Dr. Gunzi Saito Prof. Rimma N. Lyubovskaya 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):1014-1028
Radical anion salts of metal‐containing and metal‐free phthalocyanines [MPc(3?)].?, where M=CuII, NiII, H2, SnII, PbII, TiIVO, and VIVO ( 1 – 10 ) with tetraalkylammonium cations have been obtained as single crystals by phthalocyanine reduction with sodium fluorenone ketyl. Their formation is accompanied by the Pc ligand reduction and affects the molecular structure of metal phthalocyanine radical anions as well as their optical and magnetic properties. Radical anions are characterized by the alternation of short and long C?Nimine bonds in the Pc ligand owing to the disruption of its aromaticity. Salts 1 – 10 show new bands at 833–1041 nm in the NIR range, whereas the Q‐ and Soret bands are blue‐shifted by 0.13–0.25 eV (38‐92 nm) and 0.04–0.07 eV (4–13 nm), respectively. Radical anions with NiII, SnII, PbII, and TiIVO have S=1/2 spin state, whereas [CuIIPc(3?)].? and [VIVOPc(3?)].? containing paramagnetic CuII and VIVO have two S=1/2 spins per radical anion. Central metal atoms strongly affect EPR spectra of phthalocyanine radical anions. Instead of narrow EPR signals characteristic of metal‐free phthalocyanine radical anions [H2Pc(3?)].? (linewidth of 0.08–0.24 mT), broad EPR signals are manifested (linewidth of 2–70 mT) with g‐factors and linewidths that are strongly temperature‐dependent. Salt 11 containing the [NaIPc(2?)]? anions as well as previously studied [FeIPc(2?)]? and [CoIPc(2?)]? anions that are formed without reduction of the Pc ligand do not show changes in molecular structure or optical and magnetic properties characteristic of [MPc(3?)].? in 1 – 10 . 相似文献
15.
Kristof Seubert Dominik Böhme Jutta Kösters Wei‐Zheng Shen Eva Freisinger Prof. Dr. Jens Müller 《无机化学与普通化学杂志》2012,638(11):1761-1767
Metal‐mediated base pairs can be used to insert metal ions into nucleic acids at precisely defined positions. As structural data on the resulting metal‐modified DNA are scarce, appropriate model complexes need to be synthesized and structurally characterized. Accordingly, the molecular structures of nine transition metal complexes of N‐methyl‐2, 2'‐dipicolylamine (dipic) are reported. In combination with an azole‐containing artificial nucleoside, this tridentate ligand had recently been used to generate metal‐mediated base pairs (Chem. Commun. 2011 , 47, 11041–11043). The PdII and PtII complexes reported here confirm that the formation of planar complexes (as required for a metal‐mediated base pair) comprising N‐methyl‐2, 2'‐dipicolylamine is possible. Two HgII complexes with differing stoichiometry indicate that a planar structure might also be formed with this metal ion, even though it is not favored. In the complex [Ag2(dipic)2](ClO4)2, the two AgI ions are located close to one another with an Ag ··· Ag distance of 2.9152(3) Å, suggesting the presence of a strong argentophilic interaction. 相似文献
16.
Michael Sekita Beatriz Ballesteros Franois Diederich Dirk M. Guldi Giovanni Bottari Toms Torres 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(18):5650-5654
A cycloaddition–retroelectrocyclization reaction between tetracyanoethylene and two zinc phthalocyanines (ZnIIPcs) bearing one or four anilino‐substituted alkynes has been used to install a strong, electron‐accepting tetracyanobuta‐1,3‐diene (TCBD) between the electron‐rich ZnIIPc and aniline moieties. A combination of photophysical, electrochemical, and spectroelectrochemical investigations with the ZnIIPc‐TCBD‐aniline conjugates, which present panchromatic absorptions in the visible region extending all the way to the near infrared, show that the formal replacement of the triple bond by TCBD has a dramatic effect on their ground‐ and excited‐state features. In particular, the formation of extremely intense, ground‐state charge‐transfer interactions between ZnIIPc and the electron‐accepting TCBD were observed, something unprecedented not only in Pc chemistry but also in TCBD‐based porphyrinoid systems. 相似文献
17.
Silver‐Free Two‐Component Approach in Gold Catalysis: Activation of [LAuCl] Complexes with Derivatives of Copper,Zinc, Indium,Bismuth, and Other Lewis Acids
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Weizhen Fang Dr. Marc Presset Dr. Amandine Guérinot Dr. Christophe Bour Dr. Sophie Bezzenine‐Lafollée Prof. Dr. Vincent Gandon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(18):5439-5446
Complexes of type [LAuCl] (L=phosphine, phosphite, NHC and others) are widely employed in homogeneous catalysis, however, they are usually inactive as such and must be used jointly with a halide scavenger. To date, this role has mostly been entrusted to silver salts (AgSbF6, AgPF6, AgBF4, AgOTf, etc.). However, silver salts can be the source of deactivation processes or side reactions, so it is sometimes advisable to use silver‐free cationic gold complexes, which can be difficult to synthesize and to handle compared with the more robust chloride. We show in this study that various Lewis acids of the transition and main group metal families are expedient substitutes to silver salts. We have tested CuI, CuII, ZnII, InIII, SiIV, BiIII, and other salts in a variety of typical AuI‐catalyzed transformations, and the results have revealed that [LAuCl] can form active species in their presence. 相似文献
18.
Study of Regiochemical Trends During the Synthesis of Furan and 5‐(p‐chlorophenyl)Furan Containing Novel Spiropyrrolidine Library Through 1,3‐dipolar Cycloaddition Reactions
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Sahana Mallya Balakrishna Kalluraya H. S. Vidyashree Jois 《Journal of heterocyclic chemistry》2016,53(6):1859-1865
A new class of functionalized furan and 5‐(p‐chlorophenyl)furan containing spiropyrrolidines has been synthesized in moderate to excellent yields by the one‐pot, three‐component 1,3‐dipolar cycloaddition reaction of in situ generated azomethine ylides with various furan/aryl furan‐substituted chalcones as dipolarophiles. The effect of electron deficient substituents at the fifth position of the furan ring in the chalcone on the regiochemistry of the cycloaddition formed was studied. The structures of the newly synthesized cycloaddicts were proved by analytical and spectral data. 相似文献
19.
Anna M. Plonka Debasis Banerjee John B. Parise 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(11):m335-m337
The title compound, [Mg2(C12H14O4)2]n, is the first example of an s‐block metal adamantanedicarboxylate coordination polymer. The asymmetric unit comprises two crystallographically unique MgII centers and two adamantane‐1,3‐dicarboxylate ligands. The compound is constructed from a combination of chains of corner‐sharing magnesium‐centered polyhedra, parallel to the a axis, connected by organic linkers to form a layered polymer. The two MgII centers are present in distorted tetrahedral and octahedral coordination environments derived from carboxylate O atoms. Tetrahedrally coordinated MgII centers have been reported in organometallic compounds, but this is the first time that such coordination has been observed in a magnesium‐based coordination polymer. The bond valance sums of the two MgII centers are 2.05 and 2.11 valence units, matching well with the expected value of 2. 相似文献
20.
Intense Ground‐State Charge‐Transfer Interactions in Low‐Bandgap,Panchromatic Phthalocyanine–Tetracyanobuta‐1,3‐diene Conjugates
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Michael Sekita Dr. Beatriz Ballesteros Prof. Dr. François Diederich Prof. Dr. Dirk M. Guldi Dr. Giovanni Bottari Prof. Dr. Tomás Torres 《Angewandte Chemie (International ed. in English)》2016,55(18):5560-5564
A cycloaddition–retroelectrocyclization reaction between tetracyanoethylene and two zinc phthalocyanines (ZnIIPcs) bearing one or four anilino‐substituted alkynes has been used to install a strong, electron‐accepting tetracyanobuta‐1,3‐diene (TCBD) between the electron‐rich ZnIIPc and aniline moieties. A combination of photophysical, electrochemical, and spectroelectrochemical investigations with the ZnIIPc‐TCBD‐aniline conjugates, which present panchromatic absorptions in the visible region extending all the way to the near infrared, show that the formal replacement of the triple bond by TCBD has a dramatic effect on their ground‐ and excited‐state features. In particular, the formation of extremely intense, ground‐state charge‐transfer interactions between ZnIIPc and the electron‐accepting TCBD were observed, something unprecedented not only in Pc chemistry but also in TCBD‐based porphyrinoid systems. 相似文献