Soft Acid Base Theory Research Articles

Crystal structure of trans-dicarbonylbis(dimethylphenylphosphine)(N-phenylsalicylideneaminato)rhenium(I) and mer-trichloro(dimethylphenylphosphine)(N-phenylsalicylideneaminato)rhenium(IV). Comparison of Re I , Re III , Re IV , and Re V complexes with the salicylideneaminato ligand and reaction mechanisms

The crystal structures of trans-[ReI(CO)2(psal)(PMe2Ph)2](1)(psal =N-phenylsalicylideneaminate) and mer-[ReIVCl3(psal)(PMe2Ph)](2), have been determined from single-crystal diffractometer data and refined to R factors of 0.029 and 0.020. Crystal data are: a= 16.857(3), b= 10.788(3), c= 17.269(5)Å, β= 105.32(2)°, space group P21/n, Z= 4 for (1) and a= 7.981(2), b= 10.868(2), c= 13.917(1)Å, α= 99.63(1), β= 81.23(2), γ= 108.41(2)°, space group P, Z= 2 for (2). Both compounds display octahedral co-ordination and a general comparison of their bond distances with similar octahedral complexes of rhenium in its ReIII and ReV oxidation states has been carried out. Differences are mainly interpreted in terms of trans influence and Pearson's hard–soft acid–base theory. Some aspects of the reaction mechanisms of formation of ReV, ReIV, ReIII, and ReI complexes with bidentate Schiff bases are also considered on the basis of structural data.

Application of Hard and Soft Acid-Base Theory in the Study of Mixed Ligand Thiocyanate-8-hydroxyquinoline Complexes of Bivalent Metal Ions of 3d-Transitional Series

Application of Hard and Soft Acid-Base Theory in the Study of Mixed Ligand Thiocyanate-8-hydroxyquinoline Complexes of Bivalent Metal Ions of 3d-Transitional Series

The mass spectra of 1,1,1‐trichloro‐2,4‐pentanedione and its Al(III), Cr(III), Fe(III), Mn(II), Co(II) and Cu(II) complexes

AbstractThe compounds 1,1,1‐trichloro‐2,4‐pentanedione, Cu(II)tca2, Co(II)tca2, Mn(II)tca2, Al(III)tca3, Cr(III)tca3 and Fe(III)tca3 (tca1,1,1‐trichloro‐2,4‐pentanedionato, [CCl3COCHCOCH3]−) have been prepared and their mass spectra have been obtained. The mass spectral results have been compared with findings for comparable fluorinated and nonhalogenated compounds. Comparisons are made in terms of internal redox reactions and hard and soft acid base theory. Rearrangement of chloride from ligand to metal accompanied by the elimination of CO or other neutral even electron fragments emerges as an important reaction for the ions of these compounds. While the internal redox reactions characteristic of all previous β‐diketonate complex mass spectra still occur, their importance appears reduced to some degree by the facility of the chlorine rearrangement.

Relative methylmercury cation affinities in the gas phase determined by high pressure mass spectrometry

A pulsed electron beam, high pressure mass spectrometer has been used to determine equilibrium constants for the exchange of CH3Hg+ between bases; [Formula: see text] A series of aromatic, hydrocarbon bases has been studied at 417 K and several nitrogen bases have been studied at 580 K. There is a good linear correlation between differences in CH3Hg+ affinity (ΔG0) and H+ affinity for bases in each series. The single sulfur base examined ((C3H7)2S) shows anomalously high relative affinity for CH3Hg+ compared with H+ while two oxygen bases (CH3COOCH3 and C6H5NO2) show lesser relative affinity. These results are in qualitative agreement with the hard–soft acid base theory. ΔH0 and ΔS0 values have been obtained from Arrhenius plots. For a pair of aromatic bases (toluene–ethylbenzene) ΔH0 is of the same magnitude as that for H+ and ΔS0 may be calculated using partition functions for translation and external rotation. For toluene/methylacetate the difference in binding energy is much greater for H+ than for CH3Hg+ and a similar calculation of ΔS0 gives a result not consistent with the experimental value.

The carbonyl ligand as a hard and soft base

The bonding mode of coordinated carbonyl and nitrosyl ligands can be readily understood in terms of hard and soft acid-base theory.

Tin-halogen stretching frequencies and the hard and soft acid-base theory

Tin-halogen stretching frequencies and the hard and soft acid-base theory

Infrared and Mössbauer Spectral Studies on Some Tin(IV) Complexes: A Qualitative Correlitation with the Hard and Soft Acid-Base Theory

Abstract The principle of the hard and soft acid-base theory (HSAB) is that binding of hard acids with hard bases and soft acids with soft bases is preferred.1 This implies that the maximum bond strength in a series of acid-base complexes should occur, all other factors being equal, where the degree of hardness or softness of the acid and base are most nearly matched. To test this hypothesis, we prepared a number of tin(IV) complexes of varying softness with the soft base 2,5-dithiahexane (CH3SCH2CH2OCH3, DTH) and the hard base 1,2-dimethoxyethane (CH3OCH2CH2OCH3, DME). The acids employed were SnCl4, CH3,SnCl3, SnBr4, and SnI4. The complexes thus obtained were studied by infrared and Mcssbauer techniques in order to determine which, if any, of the complexes exhibited spectral details which could be correlated with HSAB.