The behaviour of the sulphate groups in the alum structures

Ledsham, A. H. C.; Steeple, H.; Hughes, Wendell L.

doi:10.1107/s0567740870003953

Cited by 26 publications

(6 citation statements)

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“…The electric field gradient, EFG, at the sites of the ions Me" and Me3") i n these alums has been calculated on the basis of a point charge model and the effective charge of the sulphur atom in the SO:@-group determined to be z = ( + 2 f 1). The NMR (NQR) results are in further support of the dynamical disorder model proposed by Ledsham et al [ 3 ] for the behavior of the sulphate groups in the alum lattice.…”

Section: Introductionsupporting

confidence: 81%

NMR and NQR investigations of nuclear quadrupole interactions in alums II. Internal motions and the temperature dependence of the electric field gradient

Weiden

Weiß

1975

Ber Bunsenges Phys Chem

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Fcstk i i r p i Gitterdynumik I Kernquadrupolrrsonrnz I Kris1ullstruli fur I Mugnetischr KernresonanzBy single crystal NMR spectroscopy the temperature dependence of the nuclear quadrupole coupling constants I ez q Q / h I in the p-alum CsAl(SO& . 12 H 2 0 was investigated. The temperature coefficient ~ ' is positive for "AI ( = 1.6. lO-'deg-l) whereas the temperature coefficient is negative for 133Cs ( z -2.6. 10-'deg-') both in the range 77 K 5 T s 300K. Similarly, the temperature coefficient of "Rb in the r-alum RbGa(S0,)2' 1 2 H 2 0 is negative ( -2 . 5 .27 C. On the basis of a pc)inl charge model calculation the opposite signs of the temperature coefficients at the sites of Mea and Me3@. respectively, are explainccl The nuclear quadrupole coupling constants of I4N in NH,AI(SO& 1 2 H z 0 , N2HsAI(S04)2. 1 2 H 2 0 , and CH.3NH3AI(S0,)2. 1 2 H z 0 are explained by the rotational motions of the ions Me@. Taking the symmetry of the electric field gradient tensor and the absolute value of e z q Q h into account, the direction of the rotational axes of the ions (N2HS)" and CH3NHf with respect to the molecular and the crystal axes has been determined.

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Section: Introductionsupporting

confidence: 81%

NMR and NQR investigations of nuclear quadrupole interactions in alums II. Internal motions and the temperature dependence of the electric field gradient

Weiden

Weiß

1975

Ber Bunsenges Phys Chem

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“…One of the aims of the structural investigations of alum crystals was the study of the behaviour of the S04-groups, since abnormally high values of oxygen atom temperature factors were found in several structure investigations in the past. These fmdings and the deduced different interpretations have been discussed in detail by Ledsham, Steeple and Hughes (1970).…”

Section: Introductionmentioning

confidence: 72%

X-Ray and neutron diffraction study of alums

Abdeen¹,

Will²,

Schäfer³

et al. 1981

Zeitschrift Für Kristallographie - Crystalline Materials

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The crystal structure of the alums, (NH3CH3)A1(S04)2 • I2H2O and (NHJAlCSOJz • I2H2O, has been determined and refined from X-ray and neutron diffraction data. The Compounds crystallize cubic in space group Pai (Z = 4) with a^ = 12.322(3)Ä and a^ = 12.242(1)Ä respectively. The positional and thermal parameters of all atoms including hydrogens have been refined by füll matrix least-squares analysis resulting in Ry, values from the X-ray and neutron data of 0.030 and 0.029 respectively for the methylammonium alum and of 0.024 and 0.014 respectively for the ammonium alum.The atoms of the cation groups (NHjCHj)^ and (NH4)^ are distributed on 8(c) and 24(

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“…Roughly in the same time, Ledsham and Steeple worked on the structure types of various chromium alums [19][20][21][22]. They concluded that practically all chromium alums are of the same type as their aluminum counterparts, with the exception of NaCrSD (this one was found to be of α and not of γ type).…”

Section: Survey Of Crystallographic Resultsmentioning

confidence: 99%

Vibrational spectra of hexaaquacomplexes. XII. On the possible anion disorder in selenate alums: prediction of the crystal structure and vibrational spectra of KAl(SeO4)2·12H2O and related alums

Petruševski

2015

Maced. J. Chem. Chem. Eng.

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A survey is given for the crystallographic and vibrational spectroscopic results of a number of alums. From both types of results (structural and spectroscopic) it is positively known that the sulfate α-alums exhibit orientational disorder of the sulfate anions along the threefold symmetry axis. Both IR and Raman spectra confirm the finding for sulfate disorder in KAl(SO 4 ) 2 ·12H 2 O. Only the Raman spectra show clearly that the sulfate anions in many K, Tl and Rb are indeed disordered, in excellent agreement with the crystallographic results [1]. The disorder depends on the nature and size of M I cations in the structure, the smaller the radius, the larger the disorder. Thus no anion disorder has been detected so far in selenate alums. The structure prediction of KAl(SeO 4 ) 2 ·12H 2 O allows the existence of disorder of the selenate groups. The latter seems to be corroborated by the study of the Raman spectra of selenate α alums. It is thus worthwhile to have the crystal structure of KAl(SeO 4 ) 2 ·12H 2 O refined, in order to check this prediction and as an additional check of the general explanation for the sulfate anion disorder in alums, offered earlier [1].Keywords: alums; crystal structure; prediction of; vibrational spectra; sulfates; selenates; anion disorder ВИБРАЦИОНИ СПЕКТРИ НА ХЕКСААКВА-КОМПЛЕКСИ. XII. ЗА МОЖНАТА НЕСРЕДЕНОСТ НА АНЈОНИТЕ КАЈ СЕЛЕНАТНИТЕ СТИПСИ: ПРЕДВИДУВАЊЕ НА КРИСТАЛНАТА СТРУКТУРА И ВИБРАЦИОНИ СПЕКТРИ НА KAl(SeO 4 ) 2 ·12H 2 O И СРОДНИ СТИПСИ Даден е преглед на кристалографските и спектроскопските резултати на голем број стипси. Од двата типа резултати (структурни и спектроскопски) со сигурност се знае дека сулфатните α-стипси покажуваат постоење на ориентациона несреденост на анјоните долж оската на симетрија од трет ред. И инфрацрвените и раманските спектри го потврдуваат наодот за несреденост на сулфатните анјони кај KAl(SO 4 ) 2 ·12H 2 O. Единствено во раманските спектри јасно се гледа постоење на анјонска несреденост во многу стипси на K, Tl и Rb, во целосна согласност со кристалографските податоци [1]. Несреденоста зависи од природата и големината на M I -катјоните во структурата: колку што е помал радиусот толку поголем е степенот на несреденоста. Кај селенатните стипси не е детектирана анјонска несреденост. Предвидувањето на структурата на KAl(SeO 4 ) 2 ·12H 2 O дозволува постоење на несреденост на селенатните групи. Последниов наод изгледа дека е во согласност и со испитаните рамански спектри на селенатни α-стипси. Според тоа, изгледа важно да се реши структурата на KAl(SeO 4 ) 2 ·12H 2 O, и за да се провери валидноста на предвидувањето, но и како дополнителен тест за порано понуденото објаснение за постоење на анјонска несреденост кај стипсите [1].Клучни зборови: стипси; кристална структура; предвидување; вибрациони спектри; сулфати; селенати; несреденост на анјоните  Dedicated to Academician Gligor Jovanovski on the occasion of his 70 th birthday. V. M. PetruševskiMaced. J. Chem. Chem. Eng. 34 (1), 73-85 (2015) 74 PROLOGUE

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The behaviour of the sulphate groups in the alum structures

Cited by 26 publications

References 1 publication

NMR and NQR investigations of nuclear quadrupole interactions in alums II. Internal motions and the temperature dependence of the electric field gradient

NMR and NQR investigations of nuclear quadrupole interactions in alums II. Internal motions and the temperature dependence of the electric field gradient

X-Ray and neutron diffraction study of alums

Vibrational spectra of hexaaquacomplexes. XII. On the possible anion disorder in selenate alums: prediction of the crystal structure and vibrational spectra of KAl(SeO4)2·12H2O and related alums

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