摘要:

Equilibrium constants have been measured for the formation of MA species, where M is divalent manganese, cobalt, nickel, or zinc, and A2−is the 3-oxo-glutarate ion. Equilibrium constants have also been measured for the reactions, where B is 2,2′-bipyridyl or 1,10-phenanthroline. These constants were obtained bypHmeasurements at 25 °C and an ionic strength of 0.60. The results are compared with those for similar systems, especially as regards the tendency to form ternary mixed complexes of the type MAB.The rates of decarboxylation of the various MA and MAB species have been measured. The resulting rate constants follow the Irving–Williams order for stability constants, except that in both MAB species the cobalt compound decomposed slightly faster than the nickel compound. The aromatic base, which had been found earlier to have very little effect in copper complexes, increased the rate constants appreciably with other metals, especially with manganese and zinc. Usually 1,10-phenanthroline has a larger effect than 2,2′-bipyridyl. Some possible explanations of the results are considered.

ISSN:0008-4042    

DOI:10.1139/v72-572

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The co-condensation reaction of atomic palladium with a dilute CO–argon mixture (1:1000) at 10°K yields intermediate carbonyls of palladium Pd(CO)nwheren = 1–3 as well as very small amounts of Pd(CO)4. Isotopic substitution experiments using12C18O were used to aid the spectral assignments. The probabilities of forming the various Pd(CO)ncarbonyl species as a function of the CO concentration in Ar are analyzed and compared with the experimental observations. An analysis of the diffusion kinetics demonstrates their usefulness in assigning bands to various species in a series of compounds such as Pd(CO)n. The data make possible the assignment of infrared absorptions at 2070, 2060, 2044, and 2050 cm−1to tetrahedral (Td) Pd(CO)4, trigonal planar (D3h) Pd(CO)3, linear (D∞h) Pd(CO)2and linear (C∞v) PdCO, respectively. Cotton–Kraihanzel force constants are calculated for Pd(CO)nand are compared with those for the analogous intermediate carbonyls of nickel, Ni(CO)n.

ISSN:0008-4042    

DOI:10.1139/v72-573

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The infrared spectra of several aliphatic thiols and of benzenethiol were measured between 2400 and 2700 cm−1, and 4800 and 5300 cm−1in a 1:1 mixture of CCl3F and C2F4Br2, at temperatures ranging from 20 to −190 °C. Dimerization takes place at low temperatures and more highly associated species also appear. Free S—H groups are present in the solutions as well as in the pure liquids, even at the lowest temperatures. The association is of thetype in aliphatic thiols; bothandbonds are found in the case of benzenethiol and α-toluenethiol. Hydrogen bonding has little effect on the anharmonicity of the S—H stretching vibration.

ISSN:0008-4042    

DOI:10.1139/v72-574

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Triplet state properties of chromone, 4-chromanone, acetophenone, and several alkyl derivatives of acetophenone were studied in a variety of solvent systems. The phosphorescence excitation method was used to monitor the energies and relative intensities of singlet–triplet absorption bands in the presence and absence of heavy atom solvents. The results, combined with earlier optical and magnetic resonance studies of such systems, illustrate the importance of solvent environment in determining fundamental properties of these excited states. Observed trends are interpreted in terms of contrasting effects of changing solvent polarity on proximate n,π* and π.π* triplet states. To describe the relative contribution of each orbital type to the phosphorescent state, the coefficients of each wavefunction must change with solvent. Correspondingly, the solvent environment should be specified whenever orbital designations are made.

ISSN:0008-4042    

DOI:10.1139/v72-575

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The compound previously reported as β-ReOCl3has been shown by analysis and single crystal X-ray diffraction to be μ-oxo-bis{oxotrichloro(O-perrhenyl chloride)rhenium(VI)}, (Re2O3Cl6)(ReO3Cl)2. The crystals were triclinic,a = 6.112(5),b = 12.876(9),c = 6.020(5) Å, α = 88.30(5), β = 95.88(5), γ = 105.36(5)°,. Intensities were measured by a densitometer from photographs recorded on an integrating precession camera. The structure was refined by full matrix least squares to give a finalR2of 0.072. The molecule is composed of a dimeric Re2O3Cl6unit with a bridging oxygen atom on the center of symmetry and an Re—O (bridge) distance of 1.847(1) Å. The remaining oxo-group on each rhenium iscisto the bridge and is strongly bonded (1.69(2) Å), and the positiontransto the terminal oxo-group is filled by a weak bond to an oxygen atom of a perrhenyl chloride molecule. The infrared spectrum of the compound has been explained in terms of the structure.

ISSN:0008-4042    

DOI:10.1139/v72-576

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

MgV2O6crystallizes in the monoclinic space groupC2/mwith lattice parametersa = 9.279(7),b = 3.502(2),c = 6.731(6) Å and β = 111.77(6)° withZ = 2. The structure was refined, at room temperature, utilizing 593 symmetry independent reflections, by full matrix least squares to a finalRvalue of 0.032. The structure consists of Mg2+lying at a site of 2/msymmetry octahedrally coordinated to oxygen atoms with a mean separation of 2.140 Å. All the remaining atoms lie in crystallographic mirror planes with the V ion coordinated to six oxygen atoms with bond distances ranging from 1.666 to 2.671 Å. The spin Hamiltonian parameters for Mn2+were determined at room temperature and again at liquid N2temperatures. As these values are invariant with temperature there is no indication of a phase transformation in Mg(VO3)2to a lower symmetry space group. The spin Hamiltonian parameters aregx = 2.0042,gy = 2.0090,gz = 2.0005;D = −459 G,E = 65 G, andA = −78 G with one of the principal axes,X, parallel to theb-axis and the Z-axis at an angle of 5° to thec-axis.

ISSN:0008-4042    

DOI:10.1139/v72-577

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Diphenylvinylphosphine reacts with dimethyl acetylenedicarboxylate to give either an equilibrium mixture of two cyclic ylidic 1:1 adducts or a strained bicyclic ylidic 1:2 adduct depending upon the reaction conditions. The adducts have been characterized by trapping them as their hydrolysis or deuterolysis products or by their Wittig reactions.trans-1,2-Bis(diphenylphosphino)ethylene reacts with the ester to give a 1:1 zwitterionic adduct which exhibits some ylidic properties and hydrolyzes by a very unexpected mechanism. Thecisisomer of this phosphine reacts with the ester to give the expected 1,4-diphosphorin which has been fully characterized.

ISSN:0008-4042    

DOI:10.1139/v72-578

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The hydrogenolysis of 2-aryloxytetrahydrofurans by excess AlH2Cl gave, in excellent yield, only those products expected fromexoC—O bond cleavage regardless of the nature of the substituent in the aryl ring. None of the 4-aryloxy-1-butanol, the product expected from ring cleavage, was detected. The reaction was very much faster than the corresponding AlH2Cl hydrogenolysis of 2-alkoxytetrahydrofurans which is known to give only ring cleavage products under similar conditions.Treatment of 2-aryloxytetrahydrofurans or pyrans with AlCl3in ether, resulted in acid-catalyzed cleavage to the corresponding phenol and dihydrofuran or dihydropyran, the latter immediately forming polymeric products. For those 2-aryloxytetrahydrofurans or pyrans, unsubstituted, or substituted with electron donor groups in the aryl ring, another product was obtained which resulted from electrophilic attack of one protonated dihydrofuran or pyran on the ortho or para position of the phenol. These rearrangement products were also obtained in small amounts as byproducts when 2-aryloxytetrahydrofurans were hydrogenolyzed with insufficient AlH2Cl.

ISSN:0008-4042    

DOI:10.1139/v72-579

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The cubic pyrochlores Cd2Nb2O7, Cd2Ta2O7, Sn2Nb2O7, Sn2Ta2O7. Cd2Sb7O7, Ca2Sb2O7, Mn2Sb2O7, Pb2Sb2O7, and related compounds were prepared and investigated by a number of methods. On heating above 700°. Ca2Sb2O7(pyrochlore) transformed to Ca2Sb2O7(weberite), while Pb2Sb2O7(pyrochlore) changed to a rhombohedrally distorted Pb2Sb2O7pyrochlore. Refinement of the crystal structures of Cd2Nb2O7and Cd2Ta2O7from powder diffractometer intensities yielded 0.434(2) and 0.434(3) respectively as the best estimates ofx(O2). Specimens of natural bindheimite and stibiconite were also examined. Stibiconite from San Luis Potosi (Mexico) was shown, on the evidence of its Mössbauer121Sb spectrum, to contain Sb(V) and Sb(III) in the approximate ratio of 0.2.BaCd2Cl6•5H2O and BaCd2Cl6•2H2O both give powder diffraction patterns of the pyrochlore type. The chlorine could be partially replaced by Br to give mixed crystals BaCd2Cl6−zBrz•5H2O almost up toz = 2.The crystal chemistry of 2–5 oxide pyrochlores and the relationship of the weberite to the pyrochlore phases are discussed.

ISSN:0008-4042    

DOI:10.1139/v72-580

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The effect of changes in the relative orientation of vicinal and geminal13C and1H nuclei, and in the disposition of adjacent substituents, on coupling between these nuclei has been examined with a variety of13C-labelled carbohydrates. Compounds synthesized for this purpose include derivatives ofD-glucose-1- and -6-13C andL-idose-6-13C, and related lactones, and the measurements have been made with p.m.r. spectra of these compounds. Vicinal13C-1H coupling, both through C—C and C—O bonds shows an orientational dependance analogous to that for protons:i.e., dihedral angles of 60–100° are associated with smaller coupling (0–3 Hz) than angles of 140–180° (4.5–5.5 Hz); sp2carbon produces splittings of almost twice these values. The observed spacing is smaller when an oxygen atom is in the plane of the coupling pathway than when out of plane, both for vicinal and geminal13C–1H interactions, and the presence of an extra oxygen also may have a notable impact on the geminal interaction. A study of rotational isomerism in these compounds indicates that the characteristics of coupling between13C and1H nuclei may fruitfully be compared with those of H–H coupling in the analysis of such dynamic systems.

ISSN:0008-4042    

DOI:10.1139/v72-581

出版商:NRC Research Press    

年代:1972

数据来源: NRC