Structure et stabilité thermique des deux formes du formiate de magnesium dihydraté

Malard, C.; Pézerat, H.; Herpin, Paulette; Tolédano, P.

doi:10.1016/0022-4596(82)90036-6

Cited by 16 publications

(15 citation statements)

References 10 publications

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“…Carboxylates are known to coordinate to metal ions in a monodentate mode, as in magnesium acetate, 11 or in a bidentate fashion under contribution of the carbonyl oxygen acting as either chelating or bridging (compare Fig. 3), as in zinc acetate dihydrate 12 or magnesium formate dihydrate 13 respectively. The changes in the carbonyl stretching IR-vibrations are characteristic for the protonation state and particular for the binding mode of carboxylates.…”

Section: Dalton Transactions Papermentioning

confidence: 99%

Metal fluoride-based transparent nanocomposites with low refractive indices

et al. 2013

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The utilisation of magnesium and aluminium fluoride nanoparticles in the preparation of transparent composites leading to materials with superior properties was investigated. Nanoscopic magnesium and aluminium fluoride has been prepared by the fluorolytic sol-gel route from the alkoxides and was surface modified by the reaction with trifluoroacetic acid or perfluorobutyric acid. IR spectroscopic experiments of the xerogels and crystal structure analysis of a trinuclear [Mg3(μ3F)(μ-TFA)6(OCH3)2(py)](3-) cluster unit indicate that the carboxylate group is bound to the particle surface in a monodentate or bidentate bridging fashion. These particles were successfully incorporated into acrylate polymers with up to 40 wt% content to give fully transparent material. Ellipsometry and m-line measurements of thin films show the reduction of the refractive index of composite films with increasing metal fluoride filler content.

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Section: Dalton Transactions Papermentioning

confidence: 99%

Metal fluoride-based transparent nanocomposites with low refractive indices

et al. 2013

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“…A search of the Cambridge Structural Database revealed only one discrete dinuclear magnesium(II) structure, dimagnesium(II) o -phenylenediaminetetraacetate, [Mg 2 (C 14 H 12 N 2 O 8 )(H 2 O) 6 ] . In the presence of simple carboxylates such as formate, magnesium(II) ions tend to form polymers …”

Section: Introductionmentioning

confidence: 99%

“…11 In the presence of simple carboxylates such as formate, magnesium(II) ions tend to form polymers. 12 In order to avoid such polymeric structures, we employed the dinucleating ligand XDK (Figure 1), where H 2 XDK is m-xylylenediamine bis(Kemp's triacid imide). 13,14 This ligand has two convergent carboxylate groups, positioned about 3 Å apart, and is useful for assembling discrete dimetallic units.…”

Section: Introductionmentioning

confidence: 99%

Carboxylate- and Phosphate Ester-Bridged Dimagnesium(II), Dizinc(II), and Dicalcium(II) Complexes. Models for Intermediates in Biological Phosphate Ester Hydrolysis

1996

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Carboxylate-bridged dimagnesium(II) complexes were synthesized and characterized by employing the dinucleating ligand XDK, where H 2 XDK is m-xylylenediamine bis(Kemp's triacid imide). The reaction of 1 or 2 equiv of sodium diphenyl phosphate with [Mg 2 (XDK)(CH 3 OH) 4 (H 2 O) 2 (NO 3 )](NO 3 ), 1(NO 3 ), afforded [Mg 2 (XDK){µ-η 2 -(PhO) 2 PO 2 }(CH 3 OH) 3 (H 2 O)(NO 3 )]‚3CH 3 OH (2‚3CH 3 OH) and [Mg 2 (XDK){µ-η 2 -(PhO) 2 PO 2 }{η 1 -(PhO) 2 PO 2 }(CH 3 -OH) 3 (H 2 O)]‚CH 3 OH (3‚CH 3 OH), respectively. These are the first structurally characterized phosphate esterbridged dimagnesium(II) complexes. The reaction of 1 with 1 equiv of bis(4-nitrophenyl) hydrogen phosphate resulted in protonation of one of the carboxylate ligands and liberation of one magnesium(II) ion to give [Mg-(HXDK) 2 (H 2 O) 2 ] (4), an octahedral complex containing two short, low barrier intramolecular OH‚‚‚O hydrogen bonds. The phosphate ester exchange rate of free and bound diphenyl phosphate in 3 in methanol solution was measured by variable-temperature 31 P{ 1 H} NMR spectroscopy and compared to that of structurally analogous dizinc(II), [Zn 2 (XDK){µ-η 2 -(PhO) 2 PO 2 }{η 1 -(PhO) 2 PO 2 }(CH 3 OH) 2 (H 2 O)] (5), and dicalcium(II), [Ca 2 (XDK){µ-η 2 -(PhO) 2 PO 2 }{η 1 -(PhO) 2 PO 2 }(CH 3 OH) 3 (H 2 O)]‚CH 3 OH, (6‚CH 3 OH), complexes. The synthesis and structural characterization of 6 is presented, along with a discussion of the differences between the carboxylate-and phosphate ester-bridged dimagnesium(II), dizinc(II), and dicalcium(II) centers. Crystallographic data are as follows. 1(NO 3 ): monoclinic, P2 1 /c, a ) 11.240(3) Å, b ) 13.019(2) Å, c ) 30.208(7) Å, ) 99.11(1)°, V ) 4365(2) Å 3 , Z ) 4, R ) 0.045, and R w ) 0.054 for 5021 independent reflections with I > 3σ(I). 2‚3CH 3 OH: monoclinic, P2 1 /c, a ) 16.611(5) Å, b ) 16.059(6) Å, c ) 21.930(9) Å, ) 93.34(6)°, V ) 5840(4) Å 3 , Z ) 4, R ) 0.069, and R w ) 0.085 for 3759 independent reflections with I > 2σ(I). 3 . CH 3 OH: monoclinic, P2 1 /n, a ) 18.912(4) Å, b ) 16.254(2) Å, c ) 21.646(5) Å, ) 112.26(2)°, V ) 6158(2) Å 3 , Z ) 4, R ) 0.060, and R w ) 0.072 for 5184 independent reflections with I > 3σ(I). 4: monoclinic, P2 1 /n, a ) 15.210(5) Å, b ) 15.772(3) Å, c ) 13.093(3) Å, ) 96.35(3)°, V ) 3122(1) Å 3 , Z ) 2, R ) 0.069, and R w ) 0.070 for 1840 independent reflections with I > 2σ(I). 6 . CH 3 OH: monoclinic, P2 1 /n, a ) 16.5471(3) Å, b ) 24.3415(6) Å, c ) 16.5865(3) Å, ) 104.2530(10)°, V ) 6475.

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“…In the secondary coordination sphere hydrogen bonds between water, hydroxyl, and carboxylato groups can be present. These carboxylato groups often form bridging structures involving the coordination of the two oxygen atoms to two different Mg 2+ centers. , Chelation, i.e., coordination of the two oxygen atoms of the same group single metal center, has never been observed for Mg 2+ carboxylates . The interactions via bridging carboxylato groups and hydrogen bonded water molecules often result in 3-dimensional sructures. − When the carboxylato substituents cause steric hindrances for such 3-dimensional structures, e.g., when the carboxylato groups contain longer chains or bulky groups, a planar structure with an extended Mg 2+ carboxylato bridge structure is formed .…”

Section: Discussionmentioning

confidence: 99%

“…These carboxylato groups often form bridging structures involving the coordination of the two oxygen atoms to two different Mg 2+ centers. 63,64 Chelation, i.e., coordination of the two oxygen atoms of the same group single metal center, has never been observed for Mg 2+ carboxylates. 65 The interactions via bridging carboxylato groups and hydrogen bonded water molecules often result in 3-dimensional sructures.…”

Section: Discussionmentioning

confidence: 99%

Telechelic Ionomers: Molecular Structure and Kinetics of Physical Gelation of Unsaturated Polyester as Studied by Solid State NMR and X-ray

2001

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The kinetics of physical gelation and the structure of telechelic ionomers have been studied by 1 H and 13 C solid-state NMR, SAXS, and WAXD. The reaction of MgO with unsaturated polyesters containing carboxylic and hydroxyl end groups leads to about a 10 3 -10 4 -fold viscosity increase in the initial solution of polymer in styrene. The results of the present study suggest that the main mechanism, involved in the viscosity increase, is determined by strong electrostatic interactions between Mg 2+ ions and the charged carboxylato chain ends, resulting in the formation of immobilized ionic multiplets and their aggregates or clusters. Molecular diffusion is the limiting step for cluster formation. SAXS, WAXD, and NMR results suggest a lamella-like structure of the clusters, which are composed of crystalline carboxylato-Mg-aqua complexes in the core part surrounded by a glassy polymer layer with a thickness of a few nanometers. Polyester chains interconnect multiplets, resulting in the formation of a physical network. The estimated distance between neighboring lamella is comparable with the end-to-end distance of network chains. The increase in the content of network chains and immobilized domains causes a large increase in viscosity and storage modulus. The effect of temperature and of ionic and hydroxyl containing additives on the thickening is discussed.

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Structure et stabilité thermique des deux formes du formiate de magnesium dihydraté

Cited by 16 publications

References 10 publications

Metal fluoride-based transparent nanocomposites with low refractive indices

Metal fluoride-based transparent nanocomposites with low refractive indices

Carboxylate- and Phosphate Ester-Bridged Dimagnesium(II), Dizinc(II), and Dicalcium(II) Complexes. Models for Intermediates in Biological Phosphate Ester Hydrolysis

Telechelic Ionomers: Molecular Structure and Kinetics of Physical Gelation of Unsaturated Polyester as Studied by Solid State NMR and X-ray

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