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Showing papers in "Inorganic Chemistry in 1981"




Journal ArticleDOI
TL;DR: In this article, the magnetic susceptibility of a Heisenberg alternating chain of S = 1/2 ions has been derived in terms of the alternation parameter, the exchange coupling constant, and the g factor.
Abstract: : Magnetic susceptibility data have been collected for catena-octanedionebis-(thiosemicarbazonato)copper(II), Cu-OTS, and catena-hexane-dionebis(thiosemicarbazonato(copper(II), Cu-HTS, in the temperature range 1.8-120 K, and the data analyzed in terms of an alternating chain Heisenberg exchange model to yield J = -10.1 + or - 0.2/cm, alpha = 0.91 + 0r - 0.02, and g = 2.06 + or - 0.02 for Cu-HTS and J = 12.9 + or - 0.2 alpha = 0.90 + or - 0.02, and g = 2.11 + or - 0.02 for Cu-OTS. Anomalies in the temperature dependent capacitance data for catena-di-micron-chlorobis(4-methylpyridine)copper(II) and catena-di-micron-bromo(N-methylimidazole)copper(II) provide evidence for structural phase transitions presumably from uniform chain structures at room temperature to alternating chain structures at low temperatures. Magnetic parameters for Cu(4-methylpyridine)2Cl2 are J = -9.6 + or - 0.2/cm, g = 2.17 + or - 0.02 and alpha = 0.67 + or - 0.02. An expression for the magnetic susceptibility of a Heisenberg alternating chains of S = 1/2 ions has been developed in terms of the alternation parameter, the exchange coupling constant, and the g factor. (Author)

236 citations




Journal ArticleDOI
TL;DR: In this article, a summary of information on the redox characteristics of the various species generated in the oxidation of ascorbate in water is presented, as well as studies on the kinetics and stochastic properties of the reaction.
Abstract: Ascorbic acid was utilized as a source of reducing equivalents in a multicomponent system that promotes the photoreduction of water. A summary of information on the redox characteristics of the various species generated in the oxidation of ascorbate in water is presented. Structures are given for ascorbic acid, ascorbate ion (HA/sup -/), dehydroascorbic acid, protonated ascorbate radical, and ascorbate radical. Data relevant to protonation equilibria, thermodynamic aspects, and reduction potentials are given as well as studies on the kinetics and stoichiometry of ascorbate oxidation reactions. The results of these studies illustrate some of the complexities of ascorbate as a reductant. Depending upon the pH and the propertes of the oxidant, H/sub 2/A, HA/sup -/, and/or A/sup 2 -/ may be the kinetically significant reducing agent(s). There is a discussion of the reactivities of the ascorbate radical/ascorbate couples toward outer-sphere redox reactions in terms of the driving force for the electron-transfer reaction and the intrinsic electron-transfer barrier associated with each of the reactants; and there is a brief discussion of the kinetics of the reduction of dehydroascorbic acid. (MWF)

176 citations



Journal ArticleDOI
TL;DR: In this paper, a stable Ru(IV)-oxo complex was shown to undergo reversible one-electron oxidations both by electrochemical means and by redox titrations using Ce(IV).
Abstract: The complex Ru(pby)/sub 2/(py)H/sub 2/O/sup 2 +/ (pby is 2,2'-bipyridine; py is pyridine) has been prepared and found to undergo two reversible one-electron oxidations both by electrochemical means and by redox titrations using Ce(IV). The one-electron oxidation product, Ru(bpy)/sub 2/(py)H/sub 2/O/sup 3 +/, has strongly enchanced properties as an acid, pK/sub a/ = 0.85 +- 0.03 at 25.0/sup 0/C, I = 1.0 M, compared to the Ru(II) complex, pK/sub a/ = 10.79 +- 0.01. The hydroxy complex, Ru(bpy)/sub 2/(py)OH/sup 2 +/, has also been isolated and characterized as its perchlorate salt. The two-electron product, Ru(bpy)/sub 2/(py)O/sup 2 +/, was shown to be a Ru(IV)-oxo complex by the results of a series of experiments including elemental analysis, solution conductivity, magnetism, and /sup 18/O labeling. Given the acid-base properties of the complexes, redox potentials for the Ru(IV)/Ru(III) and Ru(III)/Ru(II) couples have the expected pH dependences, and at pH 7 the potentials are (vs. the SCE) (bpy)/sub 2/(py)RuO/sup 2 +/ /sup 0.53 V/ (bpy)/sub 2/(py)RuOH/sup 2 +/ /sup 0.42 V/ (bpy)/sub 2/(py)RuOH/sub 2//sup 2 +/. Our ability to isolate a stable Ru(IV)-oxo complex and the general redox characteristics of the system are discussed in the context of the oxidation of water, the reductionmore » of oxygen, and the competitive formation of oxo-bridged dimers.« less

162 citations




Journal ArticleDOI
TL;DR: The benzoyl-protected dimercaptodiamides (PhCOS(CH/sub 2)/sub n/CONH)/sub 2/X (n = 1, X = (CH/ sub 2/)/sub 3/, and 0-C/sub 6/H/sub 4/) have been synthesized as discussed by the authors.
Abstract: The benzoyl-protected dimercaptodiamides (PhCOS(CH/sub 2/)/sub n/CONH)/sub 2/X (n = 1, X = (CH/sub 2/)/sub 2/, (CH/sub 2/)/sub 3/, and 0-C/sub 6/H/sub 4/; n = 2, X = (CH/sub 2/)/sub 2/ and (CH/sub 2/)/sub 3/) have been synthesized. From these, via the sodium dithionite reduction of TcO/sub 4//sup -/ in base, the technetium complexes (TcO(S(CH/sub 2/)/sub n/CONXNCO(CH/sub 2/)/sub n/S))/sup -/ (n = 1, X = (CH/sub 2/)/sub 2/, (CH/sub 2/)/sub 3/, and o-C/sub 6/H/sub 4/; n = 2, X = (CH/sub 2/)/sub 2/) have been prepared. The synthesis and characterization of the complexes, and their precursors, are presented, and the radiopharmaceutical applicability is discussed.


Journal ArticleDOI
TL;DR: In this article, a straightforward, efficient, and generalizable synthesis of symmetrically substituted 2,3,9,10,16,17,23,24,30,31-decaalkylsuperphthalocyaninates from o-dialkylbenzenes is described.
Abstract: A straightforward, efficient, and generalizable synthesis of symmetrically substituted 2,3,9,10,16,17,23,24-octaalkyl-phthalocyanines and uranyl 2,3,9,10,16,17,23,24,30,31-decaalkylsuperphthalocyaninates from o-dialkylbenzenes is described. For phthalocyanines, the approach is illustrated for methyl and n-butyl substituents, and both metal-free and nickel complexes are reported. Uranyl superphthalocyanines have been prepared with methyl and n-butyl substituents. The new complexes have been characterized by a variety of chemical and physicochemical methods. Quantitative determination of the solubilities of substituted and unsubstituted phthalocyanine and superphthalocyanine complexes in both 1,2,4-trichlorobenzene and toluene demonstrates decreasing solubility in the order (4,5-Bu/sub 2/)/sub 5/SPcUO/sub 2/ > (4-Me)/sub 5/SPcUO/sub 2/ > (4,5-Me/sub 2/)/sub 5/SPcUO/sub 2/ > SPcUO/sub 2/ > (4-Me)/sub 4/PcH/sub 2/ > Ni(4,5-Bu/sub 2/)Pc > Ni(4,5-Me/sub 2/)/sub 4/Pc > NiPc. Attempts to displace the uranyl ion from (4,5-R/sub 2/)/sub 5/SPcUO/sub 2/ with acids or Cu(OAc)/sub 2/ lead to the formation of (4,5-R/sub 2/)/sub 4/PcH/sub 2/ or Cu(4,5-R/sub 2/)/sub 4/Pc, respectively.




Journal ArticleDOI
TL;DR: In this article, the anionic complexes of the type (ML{sub x})(Me{sub 5}C{sub 6} ), where M is lithium or sodium, L is diethyl ether or N,N, N, prime, and M{prime} is neodymium, samarium, or ytterbium, have been prepared from the metal trichlorides and the pentamethylcyclopentadienide anion.
Abstract: The anionic complexes of the type (ML{sub x})(Me{sub 5}C{sub 5}){sub 2}M'Cl{sub 2}, where M is lithium or sodium, L is diethyl ether or N,N,-N{prime},N{prime}-tetramethylethylenediamine, and M{prime} is neodymium, samarium, or ytterbium, have been prepared from the metal trichlorides and the pentamethylcyclopentadienide anion. The neutral species (Me{sub 5}C{sub 5}){sub 2}NdCl(THF), (Me{sub 5}C{sub 5}){sub 2}NdN(SiMe{sub 3}){sub 2}, and (Me{sub 5}C{sub 5}){sub 2}YbCl(THF) have also been prepared. The mono-ring derivatives (Na(OEt{sub 2}){sub 2})((C{sub 5}Me{sub 5})NdCl{sub 3}) and (Me{sub 5}C{sub 5})Nd(N(SiMe{sub 3}){sub 2}){sub 2} are also described.

Journal ArticleDOI
TL;DR: In this paper, the electron transfer characteristics of molybdenum(VI) complexes of the type MoO 2 (L). where L is a tridentate dianionic Schiff base ligand, are reported.
Abstract: Molybdenum(VI) complexes of the type MoO 2 (L). where L is a tridentate dianionic Schiff base ligand, are reported. Infrared data suggest oligomerization via a Mo=0→Mo bridge which is cleaved by a wide variety of donors (D): aldehyde, amide, amine. N-oxide, sulfoxide, phosphine oxide, water, alcohol, and phosphinetroducing Mo0 2 (L)(D). The tendency of adduct formation by the molybdenyl systems increases in a particular way as L is changed. Mo0 2 (L)(D) usually shows two IR absorptions attributable to cis-Mo0 2 stretches, and on the average, species with oxygen donors vibrate at higher frequencies than those with nitrogen donors. On the basis of ligand displacement reactions D binding increases in the order CH 3 CHO 6 H 5 CHO 2 S0 2 (L)(D) is readily converted to Mo0 2 (L) in a single endothermic step. Thermal analysis data together with NMR data support the weak binding of the D ligands. The electron transfer characteristics of a number of the MoO 2 (L)(dmf) species are studied with use of voltarmmetric techniques. In general two to three reduction waves are obsened, all !mated at potentials more negative than —0.9 V vs. SCE. The chemistry and electrochemistry of a dinuclear molybdenum V) species resulting from hydrazine reduction of one Mo0 2 (L) is also briefly described.

Journal ArticleDOI
TL;DR: In this article, it was shown that the long observed progressions in the X-PtrV-X axial symmetric stretching mode on irradiation into the intervalence band are accompanied by other weaker progressions involving not only the XPtrVX equatorial symmetric bending mode but also the symmetric N O 2 stretching and bending modes.
Abstract: platinum complexes, and the Pt-N02 bond lengths imply that there is significant Pt(d,) N02(7r*) back-bonding in the complexes. This result is also implicit in the R R results, in that the long observed progressions in the X-PtrV-X axial symmetric stretching mode on irradiation into the intervalence band are accompanied by other weaker progressions involving not only the X-PtrV-X equatorial symmetric stretching mode but also the symmetric N O 2 stretching and bending modes. The Pt" Pt I " intervalence band, although axial, clearly has far reaching, though small, consequential effects on the equatorial bonds, presumably on account of both the r-acceptor nature of the nitro group as well as the anionic nature 20, 42 12-42 16



Journal ArticleDOI
TL;DR: In this article, a four-membered ring metallocycle was proposed for the hydrogen-deuterium exchange reaction that yields the four-merged ring metalocycle, (Me{sub 3}Si), where S is Th or U is U.
Abstract: The monomeric, hydrocarbon-soluble monohydrides and monodeuterides of the actinide metals (thorium or uranium) of the type HM[N(SiMe{sub 3}){sub 2}]{sub 3} have been prepared. Their reaction chemistry, n-BuLi followed by MeBr yields MeM[N(SiMe{sub 3}){sub 2}]{sub 3} and borane in tetrahydrofuran yields BH{sub 4}M[N(SiMe{sub 3}){sub 2}]{sub 3}, suggests that the hydrogen atom is hydridic. Pyrolysis of the hydrides yields the novel, four-membered ring metallocycle, [(Me{sub 3}Si){sub 2}N]{sub 2} - MCH{sub 2}Si(Me){sub 2}NSiMe{sub 3} where M is Th or U. These metallocycles are the key intermediates in the hydrogen-deuterium exchange reaction that yields {[(CD{sub 3}){sub 3}Si]{sub 2}N}{sub 3}MD.


Journal ArticleDOI
TL;DR: In this paper, the relativistically parameterized extended Hueckel molecular orbital method REX is used to explore the effects of relativity upon molecular orbital energies and compositions for compounds of heavy elements.
Abstract: The relativistically parameterized extended Hueckel molecular orbital method REX is used to explore the effects of relativity upon molecular orbital energies and compositions. The uranium compounds studied are UO/sub 2//sup 2 +/, UO/sub 2/Cl/sub 4//sup 2 -/, UF/sub 6/, UCl/sub 6/, UCl/sub 4/, U(BH/sub 4/)/sub 4/, and U(C/sub 8/H/sub 8/)/sub 2/. Other heavy element compounds studied are MI/sub 3/ (M = La, Gd, Lu), PoH/sub 2/, (eka)PoH/sub 2/, I/sub 3//sup -/, AtI/sub 2//sup -/, and RnF/sub 2/. Relativistic orbital energy parameters and atomic orbital exponents are presented as supplementary material for all elements with Z = 1 to 120 together with corresponding nonrelativistic values for all elements with Z = 1 to 100. It is concluded that the REX method provides semiquantitative estimates of spin-orbit splittings and relativistic bonding effects for compounds of heavy elements.

Journal ArticleDOI
TL;DR: In this paper, the preparation and characterization of a series of spin-crossover ferric complexes with the composition [Fe(X-SalEen)2]Y, where X-salEen results from the Schiff-base condensation of X-substituted salicylaldehyde and N-ethylethylenediamine, are reported.
Abstract: The preparation and characterization of a series of spin-crossover ferric complexes with the composition [Fe(X-SalEen)2]Y, where X-SalEen results from the Schiff-base condensation of X-substituted salicylaldehyde and N-ethylethylenediamine, are reported. Several of the complexes exhibit a gradual, but complete, spin-crossover transition from high spin to low spin in the solid state, whereas certain complexes exhibit an incomplete transition and there is a “plateau” in the Ffl/Fe vs. temperature curve. One compound, [Fe(3-OCH~-SalEen)2]PF6, experiences a sudden spin-crossover phase transition. The conversion from high spin to low spin occurs within a 2’ range around the temperature 159 K. A sensitivity of physical properties to exact compound preparation is demonstrated. In spite of the variation in the series, it is shown by variable-temperature s7Fe MBssbauer and EPR techniques that only two electronic states, the high-spin 6A, excited state and one low-spin Kramers doublet ground state, are thermally populated for any of the compounds. There is no evidence of an intermediate-spin state. The ground-state Kramers doublet in these complexes has one unpaired electron in an orbital which is largely d,.. in composition.





Journal ArticleDOI
TL;DR: In this article, the magnetic susceptibilities of polymeric iron(III) complexes of malonic, succinic, furmaric, and phthalic acids have been investigated by variable-temperature (15-300 K) magnetic susceptibility, 57Fe Mossbauer spectroscopy, and infrared spectrum analysis.
Abstract: : Polymeric iron (III) complexes of malonic, succinic, furmaric, and phthalic acids have been prepared and studied by variable-temperature (15-300 K) magnetic susceptibility, 57Fe Mossbauer spectroscopy, and infrared spectroscopy. In addition, properties of iron(III) acetate have been reinvestigated using these same techniques. The magnetic susceptibilities of these complexes have been described by a theoretical model which includes, in addition to intramodular exchange terms, a parameter describing intermolecular spin-exchange effects. As a consequence of this model it was not necessary to assume an isosceles triangular arrangement of the iron(III) ions in these materials in order to explain the magnetic data. Thus, the inclusion of an intertrimer exchange parameter, which varies from 1/2.1 cm for the acetate complex to 1/11.7 cm for the o-phthalate complex allowed for a complete description of the temperature-dependence of the magnetic susceptibilty of these compounds. Mossbauer and infrared spectroscopic studies were utilized to ascertain the correctness of oxidation state and structural assignments. (Author)