On the thermal decomposition of some cobalt hydroxide nitrates

Markov, L. K.; Petrov, Κ.; Petkov, V.

doi:10.1016/0040-6031(86)85140-1

Cited by 41 publications

(34 citation statements)

References 16 publications

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“…This band disappears with the α to β transformation, and a hydroxyl stretching mode appears at 3600 cm -1 [21]. For the anhydrous analogues, the absorption band at 3200 cm -1 may be attributed to quite strong hydrogen bonds.…”

Section: Spectroscopy Analysismentioning

confidence: 91%

“…As noted above, the color change (from pink to bluish green) after anionexchange points to the presence of cobalt(II) ions in tetrahedral surrounding. It can be predicted that the local structure of the metal-based layers is close to that of Zn 5 [21]. In these compounds, the inorganic 2d network consists of a median layer of transition metals in Oh site, with metal vacancies at the apex of which lie two metal ions in Td symmetry.…”

Section: X-ray Diffraction Studymentioning

confidence: 99%

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Structural and spectroscopic study of organic-inorganic transition metal based layered magnets

Rabu¹,

Drillon²,

Hornick³

2000

Analusis

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IntroductionRecently, a novel trend of investigation has been the combination of both molecular and solid state chemistry to build hybrid organic-inorganic materials [1]. Clearly, the research on hybrid compounds is very appealing for the design of novel 3d networks in which the physical properties of both assemblies, that are normally found in distinct materials, are in close conjunction [2][3][4][5].Smectite clay minerals (montmorillonite for instance), in which silicate layers are negatively charged by substituting divalent metal ions for trivalent ones, constitute versatile host layer structures for organic or inorganic species. A large number of such cation exchangeable layer compounds are known in which the intercalated species favor pillared structures.Anion exchangeable layered compounds are less common, probably because the anions are usually strongly bound to the metal ions, and form the framework of the crystal. Exchange of interlamellar anions by organic species (dicarboxylic acid anions) was first reported by Miyata and Kumura [6]. Then, the interlayer arrangement of anionic surfactants has been extensively studied in layered double-consisting of positively charged hydroxide layers, separated by A -anions counter-balancing the positive charge of the hydroxy layers [3,4,7,8]. In such compounds, the counterion A -is located in between the hydroxy layers, and no real chemical bond exists usually between the guest and host sub-networks. The cohesion is basically due to electrostatic interactions, and when available to weak hydrogen bond couplings.On the other hand, new hybrid magnetic materials have been prepared by anion exchange reaction, in which the exchangeable anion A -is coordinated to the divalent metal ion. The layered compounds M 2 (OH) 3 A (M = Co, Cu, and A = NO 3 -or OAc -) are shown to be well adapted for substitution reactions [9][10][11][12]. The exchange for large organic species (i.e. aliphatic chain anions) coordinating the metal ion enables to tune the basal spacing, and accordingly to modify drastically the magnetic properties [11,12]. Thus, nalkyl chain molecules involving a single anionic function (carboxylate or sulfate anion), have been used to separate basic layers (Fig. 1a).In that case, the organic spacers exhibit a saturated carbon chain, whose length is mediated by the number of carbon atoms, up to 40 Å [10]. The magnetic interaction within layers is highly dependent on the nature of the anionic function and the chain stacking, so that ferro-, ferri-or antiferromagnetic behavior may be stabilized. Clearly, the n-alkyl chains do not participate directly to interlayer interactionthey may be viewed as "neutral'' pillars -but they modulate the distance between magnetic sheets, and as a result influence through-space magnetic interactions. We have shown that, due to dipolar coupling [13], ferromagnetic 3d order is stabilized when basal spacing becomes large enough (> 10 Å). The interaction mechanism between ferromagnetic layers is then mainly driven by the divergence of the inpl...

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Section: Spectroscopy Analysismentioning

confidence: 91%

Section: X-ray Diffraction Studymentioning

confidence: 99%

Structural and spectroscopic study of organic-inorganic transition metal based layered magnets

Rabu¹,

Drillon²,

Hornick³

2000

Analusis

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“…The most common phases reported in the cobalt system are Co 2 (OH) 3 NO 3 Á 0.25H 2 O (x ¼ 0:5) and Co 7 (OH) 12 (NO 3 ) 2 Á 5H 2 O [8]. The former is a single layered hexagonal compound with the cell dimensions a ¼ 3:17 and c ¼ 6:95Å, in which all the Co 2+ ions occupy octahedral sites in brucite-derived layers.…”

Section: Introductionmentioning

confidence: 99%

“…Cu 2 (OH) 3 Cl crystallizes in the structure of mineral atacamite which is not layered, while Co 2 (OH) 3 Cl crystallizes with rhombohedral symmetry [12]. Zn 5 (OH) 8 Cl 2 (a ¼ 6:34Å; c ¼ 23:64Å) has a structure similar to that of Co 7 (OH) 12 (NO 3 ) 2 with Zn 2+ in both octahedral and tetrahedral sites [13].…”

Section: Introductionmentioning

confidence: 99%

Anion mediated polytype selectivity among the basic salts of Co(II)

Ramesh

Rajamathi²,

Kamath

2006

Journal of Solid State Chemistry

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Basic salts of Co(II) crystallize in the rhombohedral structure. Two different polytypes, 3R 1 and 3R 2 , with distinct stacking sequences of the metal hydroxide slabs, are possible within the rhombohedral structure. These polytypes are generated by simple translation of successive layers by (2/3, 1/3, z) or (1/3, 2/3, z). The symmetry of the anion and the mode of coordination influences polytype selection. Cobalt hydroxynitrate crystallizes in the structure of the 3R 2 polytype while the hydroxytartarate, hydroxychloride and a-cobalt hydroxide crystallize in the structure of the 3R 1 polytype. Cobalt hydroxysulfate is turbostratically disordered. The turbostratic disorder is a direct consequence of the mismatch between the crystallographically defined interlayer sites generated within the crystal and the tetrahedral symmetry of the SO 4 2À ions.

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“…Além dos HDL, os hidroxisais lamelares (HSL) também possuem estruturas adequadas para serem submetidos a reações de intercalação e funcionalização. Nesses compostos, parte dos grupamentos hidroxila são substituídos por ânions orgânicos ou inorgânicos, produzindo compostos neutros com a formulação genérica M +2 (OH) 2-x (A -) x .nH 2 O [10][11][12][13][14] . Esses compostos possuem íons interlamelares trocáveis, os quais podem gerar compostos pilarizados através de um processamento posterior 15,16 .…”

Section: Introductionunclassified

Intercalação e funcionalização da brucita com ácidos carboxílicos

Arízaga¹

2005

Quím. Nova

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Recebido em 23/10/03; aceito em 26/8/04; publicado na web em 12/11/04 INTERCALATION AND FUNCTIONALIZATION OF BRUCITE WITH CARBOXYLIC ACIDS. Brucite (Mg(OH) 2 ) is a structural model of several natural layered minerals as well as of synthetic layered double hydroxides (LDH). Exchange reaction studies of these compounds are well documented in the literature but surface chemical modifications, especially for brucite, are quite rare. We report the behaviour of brucite in reaction with succinic and benzoic acid in different solvents and temperatures. The compounds were analysed through X-ray diffraction (XRD) and infrared spectroscopy (FTIR). The surfaces of brucite crystals were grafted producing expansions, attributed to the arrangement of the grafted species between the layers. Keywords: brucite; grafting; carboxylic acids. INTRODUÇÃOProcessos de intercalação envolvendo matrizes derivadas da estrutura da brucita (Mg(OH) 2 ), especialmente em hidróxidos duplos lamelares (HDL), são amplamente discutidos na literatura [1][2][3][4] . As matrizes dos HDL estão intimamente ligadas à estrutura da brucita, onde íons magnésio são coordenados octaedricamente a grupamentos hidroxila. Esses octaedros estão ligados entre si através das arestas, obtendo-se lamelas "bidimensionais", que são ligadas umas às outras através de forças de van der Waals e ligações de hidrogênio.Os HDL possuem uma formulação genérica do tipo [Mrepresentam cátions passí-veis de ocuparem sítios octaédricos e A m-representa um ânion de carga m-. Nesses compostos, o cátion trivalente substitui isomorficamente um cátion divalente da estrutura do hidróxido, criando cargas residuais que são compensadas com a intercalação de ânions hidratados. As forças que mantêm esta estrutura coesa são atribuídas às forças eletrostáticas entre as lamelas positivamente carregadas e os ânions, além de ligações de hidrogênio estabelecidas entre as moléculas de água co-intercaladas e grupamentos hidroxila das lamelas.Matrizes contendo diferentes metais ou mesmo metal com diferentes estados de oxidação podem também produzir compostos semelhantes aos HDL 5,6 . Apesar de muitos artigos terem sido publicados reportando reações de troca iônica dos HDL 1-3 e compostos com estruturas semelhantes aos HDL 5,6 , os quais possuem estruturas adequadas para funcionalização, poucos são os trabalhos que abordam essa classe de reações 1,[7][8][9] . Além dos HDL, os hidroxisais lamelares (HSL) também possuem estruturas adequadas para serem submetidos a reações de intercalação e funcionalização. Nesses compostos, parte dos grupamentos hidroxila são substituídos por ânions orgânicos ou inorgânicos, produzindo compostos neutros com a formulação genérica M +2 (OH) 2-x (A -) x .nH 2 O 10-14 . Esses compostos possuem íons interlamelares trocáveis, os quais podem gerar compostos pilarizados através de um processamento posterior 15,16 . Apesar da brucita possuir superfícies interlamelares reativas e estrutura lamelar, com espaçamento basal de 4,8 Å, da qual são derivadas as estruturas tantos dos HDL qu...

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On the thermal decomposition of some cobalt hydroxide nitrates

Cited by 41 publications

References 16 publications

Structural and spectroscopic study of organic-inorganic transition metal based layered magnets

Structural and spectroscopic study of organic-inorganic transition metal based layered magnets

Anion mediated polytype selectivity among the basic salts of Co(II)

Intercalação e funcionalização da brucita com ácidos carboxílicos

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