首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
5H-Dibenzo[a, d]cyclohepten-5-ol1 can undergo Ritter reaction with acetonitrile and sulfuric acid to afford either the acetamide derivative2 or the multicyclic amide3 depending on the conditions used. The X-ray structure of the inclusion compound of3 with benzene is reported here and analysed in structural terms. This material [(C19H18N2O)–(C6H6),Cc,a=10.694(5),b=22.843(5),c=9.901(4) Å,=124.02(2)°,Z=4,R=0.054] has molecules of3 linked by –N–HO=C intermolecular hydrogen bonds to form parallel chains alongc. Additional inter-host stabilisation is achieved by face-face interactions involving one of the two benzo rings of3. A hydrogen atom of the other host benzo group participates in an edge-face interaction with the benzene guest molecule to produce the inclusion compound. Benzenebenzene inter-guest interactions provide a further, but minor, contribution to the net stability of the structure. Supplementary Data relating to this article are deposited with the British Library as supplementary publication No. SUP 82189 (10 pages).  相似文献   

2.
The mutual effect of hydrogen bonds in BHF(HHal) n complexes (Hal = F, Cl, Br, I; B = –, CH3CN, NH3; n = 1-3) was examined using the self-consistent field ab initio approach (6-31++G(d,p) and ECP-HW). When two and three equivalent H bonds are formed from the lone electron pairs of the fluorine atom of the HF molecule, the mutual weakening effect is 17% and 28%, respectively. The coefficients of the mutual effects of hydrogen bonds in HF(HHal)2 and H2O(HHal)2 bridges are close in magnitude.  相似文献   

3.
Ab initio calculations at second-order Møller-Plesset perturbation theory with the 6-31 + G(d,p) basis set have been performed to determine the equilibrium structures and energies of a series of negative-ion hydrogen-bonded complexes with H2O, H2S, HCN, and HCl as proton donors and OH, SH, CN, and Cl as proton acceptors. The computed stabilization enthalpies of these complexes are in agreement to within the experimental error of 1 kcal mol–1 with the gas-phase hydrogen bond enthalpies, except for HOHOH, in which case the difference is 1.8 kcal mol–1. The structures of these complexes exhibit linear hydrogen bonds and directed lone pairs of electrons except for complexes with H2O as the proton donor, in which cases the hydrogen bonds deviate slightly from linearity. All of the complexes have equilibrium structures in which the hydrogen-bonded proton is nonsymmetrically bound, although the symmetric structures of HOHOH and ClHCl are only slightly less bound than the equilibrium structures. MP2/6-31 + G(d,p) hydrogen bond energies calculated at optimized MP2/B-31 + G(d,p) and at optimized HF/6-31G(d) geometries are similar. Using HF/6-31G(d) frequencies to evaluate zero-point and thermal vibrational energies does not introduce significant error into the computed hydrogen bond enthalpies of these complexes provided that the hydrogen-bonded proton is definitely nonsymmetrically bound at both Hartree-Fock and MP2.  相似文献   

4.
Four copper(II) complexes of betaines, [Cu2(BET)4Cl2][Cu(BET)2Cl2]Cl2 (2), [Cu2(pyBET)4Cl2]3[CuCl4]2Cl2 (3), [Cu, (pyBET)4 (H2O)2] (NO3)4 · 2H2O (4), and [Cu2(ppBET)4(H2O)2](ClO4)4 · 4H2O (5), (BET = Me3N+CH2COO; pyBET = C5H5N+CH2COO; ppBET=C5H5N+CH2CH2COO), have been prepared and characterized by X-ray crystallography. These complexes all contain dimeric [Cu2 (carboxylato-O,O)4L2] structures [basal Cu-O=1.955(4) 1.991(2), Cu Cu=2.602(1) 2.759(1) Å] with the apical ligand L=Cl in (2) and (3) [Cu-Cl=2.415(1) 2.436(3) Å] and L = H2O in (4) and (5) [Cu-OH2=2.158(4) 2.192(3) Å]; also present are a discrete [Cu(BET)2Cl2] molecule with a compressed tetrahedral CuO2Cl2 chromophore involving two unidentate carboxylate ligands [Cu-O=1.916(2), Cu-Cl=2.254(1) Å] in (2), and a discrete C3v [CuCl4]2– anion in (3). Generally the intradimer Cu Cu distance may be correlated to the electronic repulsion of the metal-ligand bonds in the CuO4L chromophore, as well as the steric interaction between the carboxylate moieties and the apical ligand.  相似文献   

5.
An x-ray diffraction structural analysis was carried out on 1H+,10H+-1,10-diazonia-18-crown-6 diethyldithiophosphate, which exists in the crystal as isolated ionic hydrogen-bonded complexes [H2DA18C6]2+·2(EtO)2PS2 with strong inter-ion N-HS hydrogen bonds. The centrosymmetric DA18C6 dication has an unusual two-cornered conformation stabilized by a pair of weak intra-ring furcated OH(N)O hydrogen bonds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 190–192, January, 1991.  相似文献   

6.
Summary A modified synthesis of protected 2,3-dideoxyribose5 starting fromL-glutamic acid (1) is described. Reaction of5 with silylated 5-hydroxymethyluracil7 a and 5-alkoxymethyluracils7 b–e in the presence of trimethylsilyl triflate afforded an anomeric mixture of 2,3-dideoxyuridine derivatives8 a–e and9 a–e. Deprotection with methanolic ammonia and separation by chromatography gave the corresponding nucleosides10 a–e and11 a–e. Treatment of9 b–e with tri(1H-1,2,4-triazol-1-yl)phosphine oxide and subsequent reaction of12 b–e with ammonia in dioxane afforded the cytosine derivatives13 b–e which on treatment with methanolic ammonia gave the corresponding 2,3-dideoxycytidine derivatives14 b–e and15 b–e. In contrast with the parent compounds, these alkoxymethyl derivatives had no appreciable activity against human immunodeficiency virus (HIV-1).
Synthese von 2,3-Dideoxynucleosiden aus 5-Alkoxymethyluracilen
Zusammenfassung Ausgehend vonL-Glutaminsäure (1) wird eine modifizierte Synthese von geschützter 2,3-Dideoxyribose (5) beschrieben. Reaktion von5 mit silyliertem 5-Alkoxymethyluracilen7 b–e in Gegenwart von Trimethylsilyltriflat ergab anomere Mischungen der 2,3-Dideoxyuridinderivate8 a–e und9 a–e. Abspaltung der Schutzgruppe mit methanolischen Ammoniak und chromatographische Trennung ergab die entsprechenden Nucleoside10 a–e und11 a–e. Behandlung von9 b–e mit Tri(1H-1,2,4-triazol-1-yl)phosphinoxid und nachfolgende Reaktion von12 b–e mit Ammoniak in Dioxan ergab die Cytosinderivate13 b–e, welche nach Behandlung mit methanolischem Ammoniak die entsprechenden 2,3-Dideoxycytidinderivate14 b–e und15 b–e ergaben. Im Gegensatz zur Stammverbindung hatten diese Alkoxymethylderivate keine nennenswerte Wirksamkeit gegen den menschlichen Immunschwächevirus (HIV-1).
  相似文献   

7.
The host compounds 2,2-binaphthyl-3,3-dicarboxylic acid (1) and 1,13–1-terphenyl-2,4,4-tricarboxylic acid (2) have been synthesized, and crystal structures of their inclusion compounds with DMSO {1a [1·DMSO(11)];2a [2·DMSO (12)]} have been determined from single crystal X-ray diffraction data. The crystals show monoclinic symmetry withZ=4 (P21/n for1a andP21/c for2a), with the unit cell dimensionsa=11.567(1),b=10.206(1),c=17.579(1) Å,=100.50(1)° for1a, anda=14.910(1),b=6.732(1),c=26.084(1) Å,=100.41(1)° for2a. The structural models were refined toR=0.032 with 3127 reflections for1a, andR=0.035 with 3175 observations for2a, collected atT=173(1) K. Both structures comprise a characteristic molecular recognition pattern for DMSO via strong (CO)O–HO(=S) hydrogen bonds and possible C–HO contacts, the latter ones from the guest methyl groups to the carbonyl oxygen of the host carboxyl groups. In the crystals H-bonded endless chains of alternating host and guest molecules are formed, which are held together by ordinary van der Waals' forces. Additionally, host2 binds a second DMSO molecule by a single (CO)O–HO(=S) bond.Supplementary Data relating to this article have been deposited with the British Library at Boston Spa, Wetherby, West Yorkshire, U.K., as Supplementary Publication No. SUP 82186 (9 pages)  相似文献   

8.
Kao  Ya-Chen  Chen  Jhy-Der 《Structural chemistry》2004,15(4):269-276
The resulting salts of (H2bpp)MX4 · n H2O (M = Zn, X = Cl, n = 1, 1; M = Cd, X = Br, n = 0, 2; M = Hg, X = Cl, n = 1, 3; M = Cu, X = Cl, n = 0, 4; M = Cu, X = Br, n = 1, 5; M = Pt, X = Cl, n = 1, 6) were crystallized from the reaction mixture prepared by adding MX2 to the HX solution of 1,3-bis(4-pyridyl)propane (bpp), while the salt of colorless (H2bpp)SnCl6, 7, was crystallized from the reaction mixture prepared by adding SnCl2 to the HCl solution of bpp. Their structures have been determined by X-ray crystallography. All the compounds show supramolecular structures in the solid state by intermolecular hydrogen bondings and aromatic – interactions. The H2bpp2+ cations in these metal salts adopt the gauchegauche and antianti conformations with different dihedral angles for the two pyridyl rings.  相似文献   

9.
Benzophenone analog 3 has been synthesized and characterized by the X-ray diffraction (XRD) method. The compound crystallizes in a monoclinic space group P21/c with cell parameters a = 7.701(8) Å, b = 7.151(5) Å, c= 28.323(3) Å, = 104.639(4)°, Z = 4. The structure exhibits intra- and intermolecular hydrogen bonding of the type N–HO, C–HO, and N–HN. The molecules are interlinked through hydrogen bonds forming an infinite chain. This polymeric-like structure may play an important role in biological activity.  相似文献   

10.
Calculations on the hydrogen-bonded complexes HCNHF, H2OHF, ClCNHCl and (CH3)2OHCl are reported. SCF harmonic values for the HF and HCl frequency shifts are in considerable disagreement with experiment, by as much as 100 cm–1. Calculations at the MP2 (harmonic) level yield improved agreement with experiment, reducing discrepancies to the order of 10 cm–1. We have also calculated all the cubic and quartic force constants for HCNHF at the SCF level, so that the anharmonic constants, x rs can be evaluated. Although x 11 (v 1=H-F stretch) is large and negative, it is more than compensated by a positive x 16 (v 6=NH-F bend), so that the anharmonic correction to v 1 is small and positive. The validity of these anharmonistudies is examined.  相似文献   

11.
Pei  Hongxia  Lu  Sheming  Ke  Yanxiong  Li  Jianmin  Qin  Shoubo  Zhou  Shuxi  Wu  Xintao  Du  Wenxin 《Structural chemistry》2004,15(3):207-210
A new Cu(II)PMIDA compound [Cu(H2PMIDA)(phen)] 3H2O (1) (H4PMIDA = H2O3PCH2N (CH2CO2H)2,phen = 1,10-phenanthroline) has been successfully synthesized and structurally characterized. In complex 1, Cu (II) is six coordinated by chelation in a tetradentate fashion by a PMIDA ligand and by two N atoms of a phen ligand. Every phen–Cu(II)–PMIDA group connects with each other via a hydrogen bond and the edge-to-face -stacking interaction. Complex 1 crystallized in triclinic P-1 with cell dimensions of a = 7.5817(6) Å, b = 10.6980(8) Å, c = 13.1852(10) Å, =82.350(2)°, = 84.151(2)°, =78.4250(2), V= 1035.25(14) Å3, Z = 2, Dc = 1.677 Mg/m3.  相似文献   

12.
Summary. Three new complexes, namely [(nicotinic acid)2H]+I, [(2-amino-6-methylpyridine)H]+ (NO3), and the 1:1 complex between 1-isoquinoline carboxylic acid (zwitter ion form) and L-ascorbic acid were synthesized. The IR spectra revealed different types of hydrogen bonds in these compounds. The X-ray structure determination has shown the first compound to consist of a packing of [(nicotinic acid)2H]+ cations and I anions. In the dimeric cation the two nicotinic acid molecules (zwitter ions) are connected through hydrogen bonds (O–HO). Each dimer is further engaged in other hydrogen bonds with adjacent dimers giving 2D layers. The I ion is located at the inversion center. In the second compound the cation and anion are connected via hydrogen bonds formed between oxygen atoms of the NO3 anion and NH and NH2 of the cation generating a layer structure. All atoms are coplanar on mirror planes. In the 1:1 complex the two molecules are connected through hydrogen bonds formed between the two oxygen atoms of the carboxylate group of 1-isoquinoline carboxylic acid (zwitter ion) and the oxygen atoms of the two adjacent hydrogen groups of the L-ascorbic acid molecule. These complex molecules are engaged in other hydrogen bonds with each other forming a 2D system normal to the long b-axis of the unit cell.  相似文献   

13.
A new crystal modification ofN-(5-nitrofurfurylidene)isonicotinic hydrazide (1) was studied by IR spectroscopy and X-ray structural analysis. The compound studied is the product of solid-phase desolvation of solvate hydrate1 of the composition [MeCOOH · 1 · H2O]. Spontaneous elimination of solvate acetic acid results in complex overall rearrangement of the crystal structure and formation of a new system of intermolecular hydrogen bonds. The crystal hydrate of 1 : 1 composition (1c) was formed from compound1. In the crystal structure of1c molecules1 are linked in infinite chains through intermolecular C=O...W...H-N hydrogen bonds. The second hydrogen atom of the molecule of the crystallization water is involved in formation of an intermolecular O-H...N(Py) hydrogen bond with the nitrogen atom of the pyridine ring of the molecule of the adjacent chain.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2501–2505, October, 1996.  相似文献   

14.
Summary Synthesis and X-ray structure analysis of N-acetyl-,-diethylglycine-N-methylamide [CH3-Co-NH-C(C2H5)2-CO-NHCH3] are described. The compound was obtained from the corresponding N-acetyl derivative [CH3-CO-NH-C(C2H5)2-COOH] through the mixed anhydride procedure. It crystallizes as monohydrate (C9H18N2O2·H2O) in space group P21/c,a=7.139(1),b=11.823(2),c=15.778(3) Å, =122.23(1)°,V=1126.53 Å3,D m=1.20 Mgm–3 (room temperature),R=0.046 for 1523 reflections. The crystal packing is dominated by two strong hydrogen bonds between the water molecule and two carbonyl oxygen atoms and two weak H-bonds to two amide-N-atoms of symmetry-equivalent molecules. The molecular conformation is closer to a 310-helix then ana-helix.
Synthese, Kristallstruktur und Konformation von N-Acetyl-,-diethylglycin-N-methylamid
Zusammenfassung Es wird über Synthese und die röntgenographische Strukturbestimmung von N-Acetyl-,-diethylglycin-N-methyl-amid [CH3-CO-NH-C(C2H5)2-CO-NH-CH3] berichtet. Die Verbindung wurde unter Anwendung der Methode der gemischten Anhydride aus dem entsprechenden N-Acetylderivat [CH3-CO-NH-C(C2H5)2-COOH] erhalten. Sie kristallisiert als Monohydrat (C9H18N2O2·H2O) in der Raumgruppe P21/c mita=7.139(1),b=11.823(2),c=15.778(3) Å, =122.23(1)°,V=1126.53 Å3,D m=1.20 Mgm–3,D x=1.204 Mgm–3 (Raumtemperatur).R=0.046 für 1523 Reflexe. Die Kristallpackung ist dominiert durch zwei starke H-Brücken vom Wassermolekül zu zwei Carbonylsauerstoffatomen sowie zwei schwachen H-Brücken zu zwei Amid-N-atomen symmetrieequivalenter Moleküle. Die Konformation des Peptidgerüstes ist näher einer 310 als einera-Helix.
  相似文献   

15.
New inclusion complexes R4N+HCO 3 ·x(NH2)2CS·yH2O (1, R=C2H5,x=1,y=1;2, R=n–C3H7,x=2,y=0;3, R=n–C4H9,x=3,y=0) have been prepared and characterized by X-ray crystallography. Crystal data, MoK radiation:1, space groupPbca,Z=8,a=8.839(2),b=14.930(3),c=24.852(5) Å, andR F=0.063 for 1419 observed data;2, space groupC2221,Z=8,a=8.521(3),b=16.941(4),c=32.022(7) Å,R F=0.054 for 1689 observed data;3, space group ,Z=2,a=9.553(2),b=12.313(3),c=14.228(4) Å, =90.44(2),=103.11(2), =110.12(2)°,R F=0.044 for 3925 observed data. In the crystal structure of1, the thiourea molecules form hydrogen-bonded zigzag ribbons running parallel to thea axis, and the cyclic dimeric bicarbonate moieties (HCO 3 )2 together with water molecules behave likewise. A puckered layer is formed by further lateral hydrogen bonding between these two types of ribbons, and the (C2H5)4N+ cations occupy the space between adjacent layers. In the crystal structure of2, the thiourea ribbons are cross-linked orthogonally by (HCO 3 )2 unitsvia N–H...O hydrogen bonds to form a composite double layer. Half of the cations are enclosed within and the other half sandwiched between these double layers. In the crystal structure of3, the thiourea molecules form puckered double ribbons running in the [110] direction. The host framework is constructed by cross-linking the double ribbons with bridging bicarbonate dimers, yielding two channel systems aligned parallel to [100] and [111] that accommodate the cationic guests. The structural relationship between the present complexes and the classical thiourea channel adducts is discussed. Supplementary Data relating to this article have been deposited with the British Library as Supplementary Publication No. SUP 82178 (44 pages).  相似文献   

16.
A mixture ofendo-H andexo-H isomers (1a and1b) of the (4-C5Me5H)PtCl2 complex was prepared by the reaction of K2PtCl4 with C5Me5H in MeOH. The mixture of isomers reacts with CpTl in the presence of TiBF4 to give a novel complex, [(4-C5Me5H)Pt(5-C5H5)]+BF4 , as a mixture ofendo-H- andexo-H-isomers (2a and2b). The data of1H and13C NMR spectroscopy of the resulting complexes are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 514–517, March, 1994.  相似文献   

17.
Sodium salicylate (NaSal where Sal=2-hydroxybenzoate), when mixed with dibenzo-24-crown-8 (DB24C8) yields a bimetallic complex [NaSal]2DB24C8 in most polar organic media, while potassium salicylate (KSal) under similar conditions shows a tendency to yield 11 or 21 complexes depending upon medium or synthesis. However, the presence of both NaSal and KSal together results in a unique mixed cation complex of composition NaKSal2DB24C8. This product melts sharply (190-92°C) without decomposition, displays IR spectral characteristics comparable to those of [Na(Sal)]2DB24C8, and is stable in aqueous media as shown by the detectable cation effect on the UV absorption bands of Sal and DB24C8. Single crystal X-ray analysis of NaK(Sal)2DB24C8 reveals that the system represents a co-crystallization complex of individual (KSal)2DB24C8 and (NaSal)2DB24C8 molecules. The crystals are monoclinic,P21/c,a=19.976(2) Å,b=9.031(1) Å,c=25.541(5) Å,=122.065(9)°, Å3,T=298 K,Z=2+2, CuK =1.5418 Å, and 2 (2.5°–100°). FinalR factor for the 3012 observed reflections (F>3) is 0.092. Both the Na2- and K2-molecules possess crystallographic centers of symmetry with one metal and its associated anion on each side of the crown ring. However, the conformations of the crowns are very different in the two molecules, with the K2-crown being nearly planar and the Na2-crown being quite puckered. Four oxygen atoms from the DB24C8 (KO, 2.680–2.908 Å) and three carboxyl oxygen atoms (KO, 2.472–2.708 Å) from separate salicylate ions coordinate with each potassium. Three oxygens from the crown (NaO, 2.536–2.65 Å) and three carboxyl oxygens (NaO, 2.31–2.563 Å) coordinate with each sodium. The salicylate ions lie on opposite sides and nearly perpendicular (77.2°, Na2-molecule; 82.7° K2-molecule) to each crown but coordinate to both of the metal ions within a molecule. The K+K+ and Na+Na+ distances in the respective molecules are 3.95 and 3.34 Å. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82044 (18 pages).  相似文献   

18.
A crystalline 1 : 2 adduct of aquatrifluoroboron and triphenylphosphine oxide 1/2[BF3(H2O)] · Ph3PO(I) is synthesized and studied by X-ray diffraction analysis. The crystals are orthorhombic, space group Fdd2, a = 32.283 Å, b = 20.162 Å, c = 10.191 Å, Z = 16. The structure is solved by the direct method and refined by a full-matrix least-squares method in the anisotropic approximation to R = 0.054 against 2528 independent reflections (CAD4 automated diffractometer, MoK). A Ph3PO molecule has a normal structure. A [BF3(H2O)] molecule is randomly disordered relative to axis 2; populations of positions of all its atoms are 0.5. The boron atom has a distorted tetrahedral coordination with a donor-acceptor B-O(w) bond. In crystal, strong hydrogen bonds of the P=OH-O-HO=P type are formed between the H2O molecule and two Ph3PO molecules.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 1, 2005, pp. 12–16.Original Russian Text Copyright © 2005 by Chekhlov.  相似文献   

19.
The formation enthalpies (H f°) of 12 organosulfur radicals (R·) were determined for the first time from the published values of dissociation energies of R—X bonds.  相似文献   

20.
The chlorination of N-alkoxy-N-alkylureas (1) by the action oft-BuOCl proceeds regiospecifically to give stable N-chloro-N-alkoxy-N-alkylureas (2). The alcoholysis of2 leads to N,N-dialkoxy-N-alkylureas (3). The alkaline hydrolysis of3 is a new, convenient method for the preparation of dialkoxyamines.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2441–2443, October, 1992.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号