摘要:

AbstractCompounds of the type Fe(ligand)4(anion)2, with pyrazole and 5‐methylpyrazole as ligands, and I−, Br−, Cl−, NO−3and NCS−as anions, have been investigated by Mössbauer spectroscopy at 300 and 90° K.The observed centre shifts of the compounds are in the 1.29‐1.33 mm/s range at room temperature and 1.42‐1.45 mm/s range at liquid nitrogen temperatures, and fall in the lower range of the region found for Fe(II) in the high‐spin state. The observed quadrupole splittings were found to be largely dependent upon the particular combination of ligand and anion, and, for some compounds also upon the temperature.Comparison of the quadrupole splittings with previously obtained ligandfield parameters confirms the5Egground state for the Fe(II) ion, and agrees with a tetragonal symmetry for the species FeL4A2. In addition, small rhombic distortions were found to be present for the compounds with the ligand 5‐methylpyrazole. A5B2gground state is proposed for Fe(pyrazole)4(NCS)2.In all compounds the splitting of the octahedral5T2gstate is quite large, placing the5B2glevel about 2‐3 kK above the5Egstate.The lattice contribution to the quadrupole splitting (0.8‐1.6 mm/s for most compounds) is shown to be much larger than previously ass

ISSN:0165-0513    

DOI:10.1002/recl.19720910802

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe rearrangement of 5‐ethyl‐2‐methyltetrahydrofuryl ion (2) to the 2,5,5‐trimethyltetrahydrofuryl ion (4) is proceeded by a much more rapid equilibration of2with the 2,4,5‐trimethyl isomers (3,cisandtrans). These reactions are both acid catalysed and only take place in superacids (HF‐SbF5and FSO3H‐SbF5). They involve skeleton rearrangements in intermediate dications (C,O‐diprotonated alkenones), the most stable one of which has been observed directly in 1:1 HF‐SbF5.From the rates of the above and other, similar reactions the relative acidities of 1:1 HF‐SbF5, 9:1 HF‐SbF5, 1:1 FSO3H‐SbF5and 5:1 FSO3H‐SbF5have been estimated as>500:1:10−1:10−5.From the fact that2isomerizes much faster to3than to4it is concluded that in branching rearrangements of alkylcarbonium ions (e.g. linear to mono‐branched ions) the ring opening of the intermediate protonated 1,2‐dialkyl‐cyclopropane to the branched structure goes first to asecondarybran

ISSN:0165-0513    

DOI:10.1002/recl.19720910803

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe gas phase reaction between ethene and COS or CS2in a silent electrical discharge at atmospheric pressure is described. In both cases S(3P) and S(1D) atoms are formed, which react with ethene to give epithioethane and ethenethiol besides minor amounts of polymer.

ISSN:0165-0513    

DOI:10.1002/recl.19720910804

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractPMR benzene solvent shiftsandhave been measured for acetylacetonato protons of hexacoordinate (acetylacetonato)organoantimony(V) and bis(acetylacetonato)organotin(IV) compounds. The observed values correlate better with the inductive effect of substituents at the metal atom than with the molecular dipole moments of these compounds. It is demonstrated that this relation holds also for tetrahedral compounds. The stereochemistry of the benzene‐acetylacetonato group interaction is discusse

ISSN:0165-0513    

DOI:10.1002/recl.19720910805

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractStability constants of nickel(II) and zinc complexes of optically active and racemic cysteine and penicillamine (dianion: penam) in aqueous solution have been determined. For the complex Ni(penam)22−a significant stereoselective effect in favour of the racemic mixture (MLL + MDD) was observed, themesocomplex MDL having an excess Gibbs energy of 0.5‐0.6 kcal/mole (2.1‐2.5 kJ/mole) relative to the racemic mixture. For Zn(penam)22−a small effect, on the edge of significance, in favour of themesocomplex MDL was found; no stereoselectivity was observed for the cysteine co

ISSN:0165-0513    

DOI:10.1002/recl.19720910806

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractA series of stereospecific reactions, starting from (−)‐(isoPrO)MeP(O)H (I) (see Reaction Scheme), establishes that the absolute configuration of (+)‐(isoPrO)‐MeP(O)SMe(II) (R′=Me) is (R), and not (S) as previously suggested. The reassigned configuration is confirmed by X‐ray analysis. It follows that the displacement of X by Ph in isoPrO(Me)P(O)X proceeds with complete retention of configuration when X = SMe, but proceeds with complete inversion when X = F. In the case of X = Cl, the reaction proceeds at least predominantly with inversion of co

ISSN:0165-0513    

DOI:10.1002/recl.19720910807

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe results of the thermal decomposition at low pressure of Cl3P  NPCl2; NSO2Cl, Cl3P  NPCl2 NPCl2 NSO2Cl and mixtures of these compounds with Cl3P  NSO2Cl, are reported. In all cases inorganic heterocycli, containing nitrogen phosphorus and/or sulfur atoms, were obtained. The isolation of the hitherto unknown compound (NPCl2)2NSOCl is described.A short discussion of the I.R. spectra of α‐(NSOCl)3, NPCl2(NSOCl)2, (NPCl2)2

ISSN:0165-0513    

DOI:10.1002/recl.19720910808

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractEnthalpies of solution of some tetra‐alkylammonium bromides (R4NBr, R = ethyl,n‐propyl andn‐butyl) have been determined inN,N‐dimethylformamide (DMF). The concentration‐dependence of the measured heats of solution can be readily accounted for by ionic association, so that measurements at very low concentrations could be avoided. The enthalpies of transfer from water to DMF of the tetra‐alkylammonium bromides deviate substantially from those reported for the corresponding iodides. The differences can be attributed to different transfer enthalpies of the iodide and bromide ions. The enthalpies of transfer of both alkali and tetra‐alkylammonium ions fromN‐methylformamide andN‐methylacetamide to DMF are virtually constant, just like those from water and formamide to DMF when the enthalpic effect of solvophobic interaction is t

ISSN:0165-0513    

DOI:10.1002/recl.19720910809

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractIt has been found that 2‐chloropyrazine, containing an excess of15N in position 1, by treatment with potassium amide in liquid ammonia at −65° yields 2‐aminopyrazine, in which the exocyclic nitrogen contains all the excess of15N. An A(ddition)‐N(ucleophilic)‐R(ing)‐O(pening)‐R(ing)‐C(losure) mechanism is proposed. The corresponding animation of 2‐chloro[1(4)‐15N]quinoxaline at −33° leads to 2‐amino[1(4)‐15N]quinoxaline. In the last‐mentioned conversion an A(ddition)‐E(lim

ISSN:0165-0513    

DOI:10.1002/recl.19720910810

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe formation of 1:1 inclusion complexes of some alkyl methylphosphonates with α‐cyclodextrin in an aqueous acidic medium has been established. The dissociation constants (Kdiss) of the inclusion complexes have been determined at 25°. The result indicate that non‐polar groups favour the inclusion process.In one case stereospecificity in the formation of the inclusion complex was obs

ISSN:0165-0513    

DOI:10.1002/recl.19720910811

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY