摘要:

The kinetic equation for the nitrous acid catalysed nitration of naphthalene in aqueous mixtures of sulphuric acid and acetic acid has at least two kinetic terms: one first order with respect to naphthalene and one second order with respect to naphthalene. The orders with respect to nitrous acid and nitric acid vary with the conditions in the way characteristic of the electron transfer mechanism of this reaction. The second-order term with respect to naphthalene is considered to derive from the formation of the dimeric radical cation (ArH)2+•. The acidity dependence of the rate coefficients and the absence of a normal isotope effect in the reaction of naphthalene-d8are consistent with this interpretation.Keywords: naphthalene, nitration, nitrous acid.

ISSN:0008-4042    

DOI:10.1139/v89-257

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

A simple point-charge model is presented for some molecules B which assigns charges to atom centres and to nonbonding pairs, those for the latter placed at distancesralong directions α as conventionally envisaged. The magnitude δ of the charge assigned to the nonbonding pairs is chosen so that the variation of the electrostatic interaction energy between B and HF with the angular position of HF agrees with that calculated on the basis of a more complete description (DMA) of the electrostatic charge distribution of B. The charges δ in the three molecules explored (B = H2O, H2CO, and H2S) prove to be only a few hundredths of an electron at distancesrcomparable with bond distances in B.Keywords: nonbonding pairs, point-charge model, hydrogen bond, Gillespie–Nyholm model, electron localization.

ISSN:0008-4042    

DOI:10.1139/v89-258

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The crystal structure of Te(N3)3SbF6containing the first binary tellurium–nitrogen cation, triazidotellurium(IV) (Te(N3)3+), has been determined by X-ray crystallography. Single crystals of Te(N3)3SbF6are monoclinic, space groupP21/cwitha = 9.201(6),b = 8.445(4),c = 13.582(7) Å, β = 100.36(5)°,Z = 4, finalR1 = 0.036 for 1286 observed reflections. The structure consists of discrete Te(N3)3+cations and distorted octahedral SbF6−anions, with some cation–anion interactions. The average Te—Nα—Nβ—Nγbond distances in Te(N3)3+are Te—Nα, 1.994(7); Nα—Nβ, 1.237(11); and Nβ—Nγ, 1.116(12) Å. The average bond angles about the Te, Nα, and Nβatoms are 94.1(3)°, 116.5(6)°, and 173.7(9)°. Structural correlations with other TeX3+species have yielded an estimate of the electronegativity of the N3−group to be 3.1 ± 0.1.Keywords: tetratellurium (2+) cation, triazidotellurium(IV) cation, electronegativity, azide.

ISSN:0008-4042    

DOI:10.1139/v89-259

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Reaction of Cl2O6with an excess of GeCl4at room temperature yields a colorless liquid, a complex mixture. Fractional distillation leads to GeCl3ClO4and GeCl2(ClO4)2. (ClO2)2Ge(ClO4)6, a yellow-orange solid, is obtained by reacting excess Cl2O6with GeCl4. It sublimes into unstable crystals above 32 °C. Vibrational spectroscopy shows mainly unidentate perchlorato groups strongly bonded to Ge in the three compounds characterized. Ge is tetrahedrally surrounded in GeCl3ClO4while it is octahedrally surrounded in the other complexes. GeCl2(ClO4)2and (ClO2)2Ge(ClO4)6are individual entities while GeCl2(ClO4)2has a polymeric structure with Ge–Cl–Ge bridges. The structure of (ClO2)2Ge(ClO4)6is analogous to that found for (ClO2)2Sn(ClO4)6. Six unidentate perchlorato groups surround the core atom; some of them interact with ClO2+, defining a new mode of coordination for ClO4groups.Keywords: germanium, chlorine trioxide, perchlorato, syntheses, vibrational spectroscopy.

ISSN:0008-4042    

DOI:10.1139/v89-260

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The dichloro-μ-ethylidene-μ-methylene-dirhodium complex, [(C5Me5Rh)2(μ-CHMe)(μ-CH2)Cl2] (2) was the main product of the reaction of the divinyl-di-μ-methylene-dirhodium complex [(C5Me5Rh-μ-CH2)2(CH=CH2)2] (1), with HCl in toluene at −78 °C. It was identified by an X-ray crystal structure determination and spectroscopically.Keywords: vinyl, μ-methylene, μ-ethylidene, rhodium, X-ray.

ISSN:0008-4042    

DOI:10.1139/v89-261

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Solvolysis of metal(II) fluorosulfates in liquid antimony(V) fluoride according to:with M = Sn, Ni, Pd, Cu, or Ag, is found to be a clean, efficient route to the hexafluoro antimonates of the corresponding metals. Two of the compounds reported here display unusual features: Pd(SbF6)2is, like its fluorosulfate precursor, paramagnetic with the Pd2+ion in a3A2gground state, and an analysis of the ligand field spectrum is presented; Ag(SbF6)2is, unlike a recently reported paramagnetic, blue, valence isomer, diamagnetic and nearly white in color. Formulation as a mixed valency compound Ag(I)Ag(III)(SbF6)4is suggested. Low temperature magnetic susceptibility measurements (where appropriate), Raman, and IR data are reported. The hexafluoro antimonates of Ni, Pd, and Cu show antiferromagnetic exchange at very low temperatures. Pd(SbF6)2shows very weak ferromagnetism below 10 K.Keywords: fluoroantimonates of divalent metals, synthesis and solvolysis in SbF5, vibrational spectra, magnetic susceptibility measurements.

ISSN:0008-4042    

DOI:10.1139/v89-262

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

A series of tris(3-hydroxy-2-methyl-4-pyridinonato)metal(III) and tris(3-hydroxy-6-hydroxymethyl-4-pyridinonato)metal(III) complexes have been prepared in water by one-pot synthesis directly from maltol and kojic acid, respectively, and the metal ion (M = Al, Ga, In) with an appropriate amine. The pyridinones have substituents at the ring nitrogen atom (CH3, C2H5). The tris(3-hydroxy-4-pyronato)metal(III) complexes are formedinsituand these undergo nucleophilic attack by the primary amine; the appropriate tris(3-hydroxy-4-pyridinonato)metal(III) complexes are obtained. This method bypasses the sequential syntheses of ligand and metal complex, and has improved the yields of the tris(ligand)metal complexes, in particular by making them much more easily accessible. The electronic effects of binding the pyrone to the metal ions and of the substituents on the pyrone ring on the reactivity are discussed.Keywords: 3-hydroxy-4 pyridinone complexes, group 13 metal ions, one-pot synthesis.

ISSN:0008-4042    

DOI:10.1139/v89-263

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The formation of four-coordinate haloboron cations from aliphatic tertiary amine adducts of the mixed boron trihalides by heavy halogen displacement has been systematically studied by19F and11B nuclear magnetic resonance and positive ion fast atom bombardment mass spectrometry (FAB). Low-steric-hindrance donor molecules readily displace bromide ion from tertiary amine – bromodifluoroborane adducts, D•BF2Br, to form difluoroboron cations D2BF2+and DD′BF2+, but the corresponding dibromofiuoroborane and tribromoborane adducts are highly resistant to bromide ion displacement. Bis(tertiary amine)dichloroboron and -chloroiodoboron cations can be obtained by selective iodide displacement from D•BCl2I and D•BClI2. Fast atom bombardment mass spectrometry selectively detects the haloboron cations in preference to the neutral adducts in mixtures, and is a valuable complement to nmr in monitoring formation of the haloboron cations as well as any ionic by-products.Keywords: difluoroboron cations, dihaloboron cations, NMR,11B,19F, fast atom bombardment (FAB), ligand substitution, redistribution reactions.

ISSN:0008-4042    

DOI:10.1139/v89-264

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

HF/AsF5and HF/SbF5superacid mixtures react with fluorinated small-ring heterocycles such as 1,2-oxazetidines and oxetanes with consequent addition of HF to give alcohol and amine ring-opened products in high yield. Excess HF serves as solvent and reactant. Ring compounds containing both nitrogen and oxygen as heteroatoms protonate predominantly on nitrogen; a case with competing O-protonation arises in the case of a chloro-substituted oxazetidine. In general, rings containing two heteroatoms retain the heteroatom–heteroatom bond and it is a carbon–heteroatom bond that opens. The resulting OH and NH functional groups are not protonated and lost in the superacid medium due to the instability of the highly fluorinated cations that would be left behind. Most of the heterocycles react at or below room temperature, although the very weakly basic 2,2-bis(trifluoromethyl)-3,3,4,4-tetrafluorooxetane requires the stronger HF/SbF5superacid system and more severe conditions.Keywords: superacids, hydrogen fluoride, ring opening, fluorinated oxazetidines, fluorinated oxetanes.

ISSN:0008-4042    

DOI:10.1139/v89-265

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The fluorination of ruthenium tetroxide RuO4was attempted by using either fluorine or krypton difluoride KrF2in HF solution. Of the two fluorinating agents, only KrF2was found to be powerful enough to react with RuO4and to transform it into ruthenium oxide tetrafluoride RuOF4. This oxide fluoride of ruthenium VI was characterized by elemental analysis, X-ray powder diffraction, and infrared absorption spectroscopy.Keywords: ruthenium tetroxide, ruthenium oxide tetrafluoride, krypton difluoride, fluorination.

ISSN:0008-4042    

DOI:10.1139/v89-266

出版商:NRC Research Press    

年代:1989

数据来源: NRC