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1.
Helmut Fischer Normen Szesni Gerhard Roth Nicolai Burzlaff Bernhard Weibert 《Journal of organometallic chemistry》2003,683(2):301-312
Displacement of tetrahydrofuran in [(CO)5M(THF)] (M=Cr, W) by the anion [CCC(X)Y]− (X=O; NR; Y=NR′2, Ph) followed by alkylation of the resulting metalate with [R″3O]BF4 (R″=Me, Et) offers a convenient and versatile route to π-donor-substituted allenylidene complexes, [(CO)5MCCC(XR″)Y]. Allenylidene complexes in which the terminal carbon atom of the allenylidene ligand constitutes part of a heterocycle are likewise accessible by this reaction sequence. Reaction of [(CO)5M(THF)] with Li[CCC(NMe)Ph]− and subsequent protonation of the metalate afford [(CO)5MCCC(NMeH)Ph] in high yield. As indicated by the spectroscopic data of the compounds and the X-ray analyses of three representative examples, these allenylidene complexes are best described as hybrids of allenylidene and zwitterionic alkynyl complexes with delocalisation of the electron pair at nitrogen towards the metal center. Dimethylamine reacts with the amino(phenyl)allenylidene complex [(CO)5CrCCC(NMe2)Ph] (7a) by addition of the amine across the CαCβ bond to give selectively the E-alkenyl(amino)carbene complex [(CO)5CrC(NMe2)CHC(NMe2)Ph] (12). In contrast, the reaction of dimethylamine with the amino(methoxy)allenylidene complex [(CO)5CrCCC(NMe2)OMe] (1a) proceeds by addition of the amine to the Cγ atom and subsequent elimination of methanol to give the substitution product [(CO)5CrCCC(NMe2)2] (13). Triphenylphosphane neither adds to the Cα nor the Cγ atom of 7a but upon irradiation displaces a CO ligand to form a cis-allenylidene(tetracarbonyl)phosphane complex 15. 相似文献
2.
Domino addition-Wittig olefination reactions of α-hydroxy esters immobilized on polystyrene with Ph3PCCO to give resin-bound tetronates proceed as readily as in solution. α-Hydroxy allyl esters can react to give either supported allyl tetronates or the corresponding Claisen-rearranged 3-allyltetronic acids, depending on conditions. 相似文献
3.
The reaction of methyl hypofluorite (MeOF) with certain fluoroolefins, such as CF2CF2, CF2CFCF3, CF2CFOCF3, CF2CFOMe, CF2CClF, CF2CHF, CF2CH2, CHFCH2, CF2CFCFCF2, occurred in CD3CN or in the presence of NaF. Using neat MeOF in the presence of NaF was a novel method and gave good results. We observed that when more than three fluorine atoms are bonded to the CC double bond, the addition products were obtained in mostly good yields. 相似文献
4.
Bin Fei 《European Polymer Journal》2003,39(10):1939-1946
FTIR spectroscopy was used to verify the presence of intermolecular hydrogen bond (inter-H-bond) between poly(3-hydroxybutyrate co-3-hydroxyvalerate) (PHBV) and bisphenol A (BPA). By monitoring the spectral changes during PHBV crystallization and blends dissociation, the absorptivity ratio of CO bonds in crystalline and amorphous regions in PHBV and that of H-bonded and free CO in PHBV/BPA blends were experimentally determined as 1.40 and 1.68, respectively. Using curve-fitting program, the CO absorptions in spectra of blends were ascribed to three types of bonds: amorphous, crystalline and H-bonded CO. The crystallinity of PHBV and the fraction of H-bonded CO were calculated. These results indicated that the H-bond clearly suppressed the PHBV crystallization. Furthermore, the fraction of BPA molecules that simultaneously formed two hydrogen bonds (H-bonds) with CO was estimated. It revealed that there existed a H-bond network in PHBV/BPA blends. This network was compared with the covalent network by estimating the number of atoms between every two adjacent crosslink points in chain. Up to the high density of H-bond discussed in this paper, there was always a certain part in PHBV that crystallized due to the dynamic character of hydrogen bonds; however, the hydrogen bonds significantly reduced the crystallization rate of PHBV. 相似文献
5.
Erich Kleinpeter Sabrina Klod Mária Šamaliková Zora Šusteková 《Journal of Molecular Structure》2003,645(1):17-27
The characteristic vibrations (νCO and νCC) of a large number of hydantoin derivatives are reported. Especially the very fine correlations νCO(sym) versus νCO(asym) (r2=0.985) but also successful correlations of the vibration wave numbers to HAMMETT's substituent constants and some other experimental parameters (pKs, OxPot, RedPot) as well, corroborate reassignments of previously obtained results [Monatsh. Chem. 92 (1961) 361] and prove the doublet obtained in the region of the CO stretching vibrations to be the symmetrical and anti-symmetrical vibrational modes of a mechanically coupled system of two quasi-symmetrical CO bonds. 相似文献
6.
Rosica MladenovaMilena Ignatova Nevena Manolova Tsvetanka PetrovaIliya Rashkov 《European Polymer Journal》2002,38(5):989-999
Polyethers with 8-hydroxyquinolin-2-yl end groups (HOQCHN-POE-NCHQOH) were prepared by reaction between polyethers having amino end groups (Jeffamines ED®) and 8-hydroxyquinoline-2-carboxaldehyde. The HOQCHN-POE-NCHQOH polymers were characterized by size-exclusion chromatography, UV, IR, 1H and 13C NMR spectroscopy, and MALDI-TOF mass spectrometry. The complexation between HOQCHN-POE-NCHQOH and Fe3+ was studied by UV, IR spectroscopy and differential scanning calorimetry. The UV-irradiation of the complexes caused photodegradation of the polyether chains. It was shown that HOQCHN-POE-NCHQOH had high efficacy on remedying iron-deficient maize plants and exhibited very low-antibacterial activity towards non-pathogenic soil bacteria (B. subtilis). 相似文献
7.
A new method of analytical determination of some thiolo (PS) and thiono (PS) group containing phosphorus insecticides using a coulometric titration with the anodically generated chlorine and biamperometric end-point detection was described. The method worked well for compounds containing one (methamidophos) or two PS bonds (iso-malathion) or one PS bond (fenitrothion) but failed for compounds containing both PS and PS bonds (malathion, dimethoate) or additional sterically hindered CSC bond (fenthion). Based on the found number z of electrons transferred per mol of oxidized compounds, mechanistic pathways for chlorination of PS and PS containing thiophosphorus insecticides with molecular chlorine in aqueous, acidic medium were proposed. 相似文献
8.
Allenic imidothioates, H2CCC(Ph)C(SMe)NR (R = Me, t-Bu, Ph) have been obtained in good yields by reaction of 1,3-dilithiated 1-(2-propynyl)benzene with isothiocyanates and successive addition of t-butyl alcohol and methyl iodide. Heating the imidothioates at ∼120 °C gave an iminocyclobutene as the only isolated product (if R = t-Bu), a ∼4:6 mixture of a 2,3-dihydropyridine and an iminocyclobutene (if R = Me) or a 3:1 mixture of a quinoline and an iminocyclobutene (if R = Ph). 相似文献
9.
The mechanism of grafting styrene-butadiene-styrene (SBS) tri-block copolymer with maleic anhydride (MAH) initiated by benzoperoxide (BPO) or 2,2′-azo-bis-isobutyronitrile (AIBN) was studied by FTIR and 1H NMR spectroscopies. The variation of CC (double bond) content in SBS-g-MAH was used to verify the different graft mechanisms of BPO and AIBN, indicating that the chemical initiation mechanisms of MAH grafted onto SBS of AIBN is different from that of BPO. The graft reaction occurs by addition on CC for AIBN, while by removal of an allylic hydrogen atom from SBS and by addition on CC at the same time for BPO. The graft efficiency of AIBN is higher than that of BPO in this system. 相似文献
10.
Zied Hassen 《Journal of fluorine chemistry》2003,121(2):177-183
Ten phosphorylated β-hydrazones of structure R2P(O)C(NNHRF)CHR2′ were prepared in 54-91% yield by heating the allenes R2P(O)CHCCR2′ with fluorinated hydrazines H2NNHRF in chloroform or methanol [R=Ph, OCH2C(Me)2CH2O or OCH2C(Me)(Pr)CH2O, R′=H or Me and RF=CH2CF3 or C6F5]. Two cyclohexyl derivatives were prepared similarly from R2P(O)CHCCy. The triphenyl derivatives Ph2P(O)CH2C(NNHCH2CF3)Ph and Ph2P(O)CH2C(NNHC6F5)Ph were made in 91 and 68% yield by heating the ketones Ph2P(O)CH2C(O)Ph with an ethanol solution of the corresponding hydrazines. The stereochemistry of the hydrazones was determined by multinuclear NMR experiments. Compounds with C(NNHRF)Me groups exist as a mixture of Z and E isomers, with the Z form predominating (fluorinated group syn to phosphorus). Those with C(NNHRF)CHMe2, C(NNHRF)Cy or C(NNHRF)Ph groups were formed selectively, the Z isomers being the only products. The results are explained by steric hindrance, the bulkier isopropyl, cyclohexyl or phenyl group disfavouring the E configuration. , , , NMR data, coupling constants and IR data are reported. 相似文献
11.
Zhaofu Fei 《Journal of fluorine chemistry》2003,121(1):79-81
The title compound RFC(O)NC(NMe2)2 (2) was prepared in virtually quantitative yield by reacting RFC(O)Cl with two equivalents of N,N,N′,N′-tetramethylguanidine and structurally characterized by X-ray diffraction. Due to severe steric crowding, the carbonyl group approaches a perpendicular arrangement (torsion angle of 70.1(2)°) with respect to the phenyl ring. 相似文献
12.
Cycloaddition reactions between 5-ethoxyoxazole derivatives [2,4-dimethyl 5-ethoxyoxazole and 4-methyl 5-ethoxyoxazole] and various trifluoromethyl alkenes [ethyl 4,4,4-trifluorocrotonate CF3CHCHCO2Et, 3,3,3-trifluoro 1-(phenylsulfonyl)-1-propene CF3CHCHSO2Ph and 2-(trifluoromethyl) propenoic acid CF3(HO2C)CCH2] gave several trifluoromethyl-substituted pyridine systems in moderate yield (20-56%). Their structures were determined by multinuclear NMR techniques including 1H-13C HETCOR spectroscopy. 相似文献
13.
Björn GustafssonMikael Håkansson Gunnar WestmanSusan Jagner 《Journal of organometallic chemistry》2002,649(2):204-208
The complex 2-allyl-6-methylphenoxocopper(I) has been prepared by reaction between mesitylcopper(I) and 2-allyl-6-methylphenol. Crystallographic studies show that the compound is tetrameric with a distorted cubane-type copper(I)-oxygen core, and with additional π-coordination of the ligand to copper through the alkene functionality (ν(CC)=1520 cm−1). The ligands thus act both as chelates and as bridges between adjacent copper(I) centres. Copper(I) exhibits trigonal pyramidal coordination geometry with CuC distances to the CC group of 1.976(9) and 2.017(11) Å and CuO distances of 1.973(6), 2.021(6) and 2.577(6) Å, respectively. 相似文献
14.
Ketenylidenetriphenylphosphorane, Ph3PCCO (2), reacts selectively with the ω-hydroxy group of the alkene-carbene complexes (OC)4CrC(η2-NMeCH2CHCHCH2OH)R1 (1) (R1=Me: (1a); Ph: (1b)) to give the acyl ylide terminated complexes (OC)4CrC[(4,5-η2)-NMeCH2CHCHCH2O(O)C-CHPPh3]R1 (3) (R1=Me: (3a); Ph: (3b)). Complexes 3 undergo Wittig alkenation reactions with aldehydes such as 2-alkynals, R2-CC-CHO (R2=H, SiMe3, Ph), to give the corresponding 4Z, 9E-dien-11-ynes (OC)4CrC[(4,5-η2)-NMeCH2CHCHCH2O(O)C-CHCH-CC-R2]R1 (4-6) (R1=Me, R2=H, SiMe3, Ph: (4a-6a); R1=Ph, R2=H, SiMe3, Ph: (4b-6b)). All complexes were characterized in solution by one- and two-dimensional NMR spectroscopy (1H, 13C, 29Si, 31P, 1H/1H COSY, 13C/1H HETCOR, 31P/31P EXSY). 相似文献
15.
Tungsten(0) carbene complexes of the type (OC)5WC(NMeCH2CHCHCH2OH)R 2 (R=Me: 2a; R=Ph: 2b) were generated by aminolysis of (OC)5WC(OMe)R with cis-NHMeCH2CHCHCH2OH. Like their Cr-congeners 1, complexes 2 exist at room temperature as mixtures of Z- and E-isomers with regard to the C-N bond. The metallacyclic complexes (OC)4WC(η2-NMeCH2CHCHCH2OH)R (4) were obtained in good yields upon photo-decarbonylation of 2. Deprotonation/silylation of the complexes (OC)4MC(η2-NMeCH2CHCHCH2OH)Me (M=Cr: 3a; M=W: 4a) with one equivalent of nBuLi/Me3SiCl gave (OC)4MC(η2-NMeCH2CHCHCH2OSiMe3)CH3 (M=Cr: 5; M=W: 6), whereas with two equivalents of nBuLi/Me3SiCl complexes (OC)4MC(η2-NMeCH2CHCHCH2OSiMe3)CH2SiMe3 (M=Cr: 7; M=W: 8) were formed. Hydrolysis of the latter yielded selectively (OC)4MC(η2-NMeCH2CHCHCH2OH)CH2SiMe3 (M=Cr: 9; M=W: 10). The complexes 1-10 were analyzed in solution by one- and two-dimensional NMR spectroscopy (1H, 13C, 29Si, 1H/1H COSY, 1H/1H NOESY, 13C/1H HETCOR). 相似文献
16.
Maciej PisklakFranciszek Herold Romana Anulewicz-OstrowskaIwona Wawer 《Journal of Molecular Structure》2002,605(1):85-92
13C cross-polarisation magic angle spinning NMR data have been reported for four derivatives of 4-aryl-octahydro-pyrido[1,2-c]pyrimidine-1,3-dione and the X-ray diffraction data for two (with 2′-Me and 2′-OMe). The crystal structures show the presence of centrosymmetric cyclic dimers with intermolecular C1O?H-N or C3O?H-N hydrogen bonds, the configuration at the chiral centres (C4 and C4a) was determined as RR (SS). The twisting of aromatic ring at C4 with respect to the pyrido[1,2-c]pyrimidine skeleton is about 68-109°. 相似文献
17.
Angelika Hermann 《Journal of fluorine chemistry》2004,125(6):917-921
The geometric structure of trifluoroacetic anhydride, CF3C(O)OC(O)CF3, has been studied by gas electron diffraction (GED) and quantum chemical calculations (MP2 and B3LYP with 6-31G* basis sets). The GED analysis results in a single conformer with synperiplanar orientation of the two CO bonds. This analysis, however, cannot discriminate between a planar equilibrium structure (C2v symmetry) with large amplitude torsional motions around the OC bonds and a nonplanar equilibrium structure (C2 symmetry) with a low barrier at the planar arrangement. An effective dihedral angle φ(COCO=18(4)° is obtained. Both quantum chemical methods predict a nonplanar equilibrium structure of C2 symmetry and φ(COCO)=16.5° and 13.9°, respectively. 相似文献
18.
Natalya V. Belova 《Journal of Molecular Structure》2004,689(3):255-260
The geometric structure of dimethyl malonate, CH3OC(O)-CH2-C(O)OCH3, was studied by gas electron diffraction (GED) and quantum chemical methods. We conclude that only diketo conformers exist in the gas phase. According to the GED refinement, a mixture of two diketo conformers is present: 69(10)% (ac,ac) conformer with C2 symmetry (both CO bonds anticlinal relative to the opposite C-C bond) and 31(10)% (sp,ac) conformer with C1 symmetry (one CO bond with synperiplanar, the other CO bond with anticlinal orientation). Ab initio calculations, however, predict a preference of the (sp,ac) conformer rather than the (ac,ac) form. 相似文献
19.
A.V. Rudnichenko 《Journal of fluorine chemistry》2004,125(9):1351-1356
2-Polyfluoroalkyl-5-methoxycarbonylmethylene-thiazolin-4-ones react as dienophiles on the exo-cyclic ylidene bond to give spiro-derivatives and as 1,3-dienes with olefins to give dihydropyranothiazole derivatives. The endo-cyclic CN bond in these compounds do not enter into the cycloaddition reactions. 相似文献
20.
Yudong CaiBrian P Roberts 《Tetrahedron letters》2003,44(25):4645-4648
Terminal alkenes of the type H2CC(OR1)X, in which R1 is a tertiary alkyl or a 1-cyclopropylethyl group and X=Ph, OSiMe2But, OEt or H, undergo radical-chain reactions with organic halides R2Hal to give carbonyl compounds R2CH2C(O)X. 相似文献