Kamal Boubekeur

Synthesis through an in situ esterification process and characterization of oxo isopropoxo titanium clusters

Three titanium oxo-isopropoxo clusters Ti 6 O 4 (OOCue5f8CH 3 ) 4 (OPr 1 ) 12 ( 1 ), Ti 12 O 16 (OPr 1 ) 16 ( 2 ) and Ti 12 O 16 (OPr 1 ) 16 ·1.4CH 2 Cl 2 ( 3 ) are obtained by refluxing Ti(OPr 1 ) 4 with 1.2 equivalents of carboxylic acids over two days. The molecular structures of Ti 6 O 4 (OOCCH 3 ) 4 (OPr 1 ) 12 ( 1 ) and Ti 12 O 16 (OPr 1 ) 16 · 1.4CH 2 Cl 2 ( 3 ) have been resolved by single crystal X-ray diffraction. The titanium oxo organo cores of these clusters are also characterized in solution by 17 O NMR spectroscopy and in solid-state by 13 C CP MAS NMR spectroscopy.

Synthesis and crystal structure of two new rare earth trimesate complexes: ErTMA(H2O)5·3.5H2O and YTMA(H2O)6

Abstract Two lanthanide complexes with trimesic acid have been obtained and structurally characterised. Er[C6H3(COO)3](H2O)5·3.5H2O crystallises in the monoclinic space group C2/c with unit cell dimensions of: axa0 =xa014.7396(15), bxa0=xa016.9874(15), cxa0=xa014.4591(14)xa0A, βxa0=xa0118.754(9)° and Zxa0=xa08. Y[C6H3(COO)3](H2O)6 crystallises in the monoclinic space group Cc with unit cell dimensions of: axa0=xa011.373(2), bxa0=xa017.850(3), cxa0=xa07.134(1)xa0A, βxa0=xa0119.14(3)° and Zxa0=xa04. Both structures consist of an extended network of metal ions coordinated by trimesate ions. The observations are analysed in terms of steric crowding about lanthanide atom using a cone-packing model.

A new family of Er(III) complexes: from chains to nanotubes

Abstract The reaction, in a gel medium, of Er(III) chloride with the trisodium salt of benzene-1,3,5-tricarboxylic acid (H3TMA) yielded three different kind of crystals. All three have been structurally characterized. ErTMA(H2O)5·3.5H2O (1) crystallizes in C2/c with a=14.7396(15), b=16.9874(15), c=14.4591(14) A, β=118.754(9)° and Z=8. Its crystal structure has been reported elsewhere already. It consists of juxtaposed criss–cross chains. ErTMA(H2O)3·1.5H2O (2) has been found to be isostructural to the Gd(III) complex reported already. It crystallizes in C2/c with a=20.452(2), b=9.973(1), c=15.251(1) A, β=125.68° and Z=8. Its structure consists of parallel double-sheet networks based on honeycomb-like motifs. Er3TMA3(H2O)8·4H2O (3) crystallizes in P1 with a=9.988(2), b=15.656(3), c=19.698(3) A, α=110.77(2), β=100.63(2), γ=100.58(2)° and Z=2. Its structure consists of parallel tube like layers based on the honeycomb-like molecular motifs already observed in 2. The crystal structure is reported herein. A predominant phase diagram has been established versus the concentrations of the gel medium and of the solutions. Heating one of them progressively liberates water molecules, which finally leads to ErTMA (4), which can reversibly bind water reforming 1.

Re-investigation of the Er3+–C2O42––H2O system: from the classical ceramic precursor to a new nanoporous molecular material potential precursor

Abstract This paper focuses on the crystallographic diversity observed for the compounds obtained, by reacting potassium oxalate with Er(III) chloride, in gel media. Three lanthanide and oxalate compounds are described two out of the three are simple lanthanide oxalate complexes while the other one is a mixed lanthanide–alkaline oxalate complex. All three have been structurally characterized. 1, namely Er2(C2O4)3(H2O)6·4 H2O, crystallizes in the space group P21/c (system monoclinic) with axa0=xa011.3590(2) A, bxa0=xa09.6162(2) A, cxa0=xa09.9401(2) A, βxa0=xa0118.723(9)° and Zxa0=xa04. Its crystal structure has been found to be identical to the one already reported. It consists of parallel honeycomb-like molecular layers. 2, namely KEr(C2O4)2·4 H2O, has been found to be isostructural to the Y(III) homologous complex already reported. It crystallizes in the space group I41/amd (tetragonal system) with axa0=xa011.4145(14) A, cxa0=xa08.893(2) A and Zxa0=xa04. Its structure consists of channels along the c axis spreading over the (ab) plane with a square cross section. 3, namely Er2(C2O4)3(H2O)6·12 H2O, crystallizes in the space group R 3 (trigonal system) with axa0=xa030.8692(10)A, cxa0=xa07.2307(2)A and Zxa0=xa012. This compound has, to the best of our knowledge, never been structurally described. It is the first three-dimensional lanthanide oxalate ever reported. Its crystal structure exhibits channels with hexagonal cross-sections spreading along the c → axis. The diameter of the channels is as large as 12xa0A. They are filled with crystallization water molecules. To cite this article: M. Camara et al., C. R. Chimie 6 (2003).

Coordination polymers incorporating light lanthanide ions

Abstract The reaction, in a gel medium, of Sm(III) chloride with the trisodium salt of benzene-1,3,5-tricarboxylic acid (H3TMA) yielded three different kinds of crystals. All three have been structurally characterized. 1, namely SmTMA(H2O)6 crystallizes in Cc with a=11.4818(12) A, b=18.062(2) A, c=7.219(1) A, β=118.5432(11)° and Z=4. Its crystal structure has been found to be isostructural to the Y(III) complex already reported. It consists of juxtaposed ribbon-like molecular motifs. 2, namely SmTMA(H2O)5·H2O has been found to be isostructural to the Er(III) complex already reported. It crystallizes in P-1 with a=7.6305(15) A, b=9.9654(15) A, c=11.219(2) A, α=106.98°, β=103.52(2)°, γ=107.50(2)° and Z=2. Its structure consists of juxtaposed chains. 3, namely Er3TMA3(H2O)3·1.5H2O crystallizes in C2/c with a=20.511(2) A, b=10.020(1) A, c=15.294(2) A, β=125.53(1) and Z=8. Its structure consists of parallel double-sheet networks based on honeycomb-like motifs. Heating 1 liberates water molecules and finally leads to SmTMA, namely 4, which can reversibly bind water reforming 1.

Neutral and Cationic Hexanuclear Rhenium Phosphine Clusters with μ3-(Phosphido-Chalcogenido), μ3-(Arsenido-Chalcogenido), and μ3-(Imido or Oxo-Chalcogenido) Hetero Ligand Shells

Reactions of dry THF/MeCN solutions of Ca[Re6SCl(Cla)6] with silylated derivatives E(SiMe3)2 (Eu200a=u200aPhAs, PSiMe3, HN, O, S) and addition of trialkylphosphine PPr3 afford in high yields and at room temperature either the neutral clusters [Re6SX(PPr3)] (1: Xu200a=u200aAs, 2: Xu200a=u200aP) or the ionic compounds [Re6SX(PPr3)]2+u200a· [Re6S6Cl8]2– (3: Xu200a=u200aNH, 4: Xu200a=u200aO, 5: Xu200a=u200aS). The compounds 1–5 were characterised by X-ray crystal structure analysis. A di-substitution reaction occurs on the {Re6SCl}4+ cluster core, where the two inner μ3-chloro ligands Cli are substituted by X (Xu200a=u200aAs, P, NH, O, S) and all six terminal chloro ligands Cla are exchanged by terminal PPr3-ligands. n n n nNeutrale und kationische hexanukleare Rhenium–Phosphin-Cluster mit μ3-(Phosphido-Chalcogenido), μ3-(Arsenido-Chalcogenido) und μ3-(Imido oder Oxo-Chalcogenido) hetero-Ligandenspharen n n n nReaktionen von Ca[Re6SCl(Cla)6], gelost in trockenem THF/MeCN, mit silylierten Derivativen E(SiMe3)2 (Eu200a=u200aPhAs, PSiMe3, HN, O, S) und Trialkylphosphin PPr3 ergaben bei Raumtemperatur in hohen Ausbeuten die neutralen oder ionischen Clusterverbindungen [Re6SX(PPr3)] (1: Xu200a=u200aAs, 2: Xu200a=u200aP) bzw. [Re6SX(PPr3)]2+[Re6S6Cl8]2– (3: Xu200a=u200aNH, 4: Xu200a=u200aO, 5: Xu200a=u200aS). 1–5 wurden mittels Rontgenstrukturanalyse charakterisiert. Eine zweifache Substitution erfolgte am {Re6SCl}4+-Clusterkern, bei welchem die beiden inneren μ3-Chlorliganden Cli durch X (Xu200a=u200aAs, P, NH, O, S) und alle sechs terminalen Chlorliganden Cla durch terminale PPr3-Liganden ersetzt wurden.

A new polyoxo–alkoxo titanium cluster of the Keggin family: synthesis and characterization by X-ray diffraction and NMR spectroscopy

The new [Ti17O24(OPri)20] cluster 1, that can be described as a non-charged lacunar super-Keggin complex, adopts a pseudo-D2d symmetry as established by X-ray diffraction and solution NMR studies.

Crystal engineering and [C-H •••O] hydrogen bonds at the organic/inorganic interface. The bi-continuous hybrid composite, κ(2/3-3)-(EDT-TTF)8[Ca(H2O)4]2(TeW6O24)· 7H2O2

Les trente molecules deau participanr a la formulation du compose decrit dans le titre et obtenu par electrocristallisation sont confinees a linterface organique/inorganique ou elles deviennent soigneusement ordonnees et participent, au meme titre que les anions couronnes dAnderson, a la construction dun polymere de coordination bidimensionnel a partir des premieres et deuxiemes spheres de coordination des atomes de calcium. Elles sont egalement engagees dans un ensemble de liaisons hydrogene [C-H…O] dont on demontre quil organise, in fine, la distribution des electrons au sein des couches dethylenedithiotetrathiafulavalenium (EDT-TTF) qui adoptent, quant a elles, un mode nouveau de pavage de la couche du type kappa.

[NBun4]4[(Re6S5OCl7)2O], an oxo-bridged siamese twin cluster of two hexanuclear oxochalcohalide rhenium clusters

A report of the solid state synthesis and X-ray crystal structure analysis of [NBun4]4[(Re6S5OCl7)2O], the first oxo-bridged, tetravalent hexanuclear oxochalcohalide rhenium cluster.

Novel infinite three-dimensional network of neutral fullerene molecules in (C60)8(twin-TDAS)6

The crystal structure of (C60)8(twin-TDAS)6 [twin-TDAS = C4S6N4 = 3,3,4,4-tetrathiobis(1,2,5-thiadiazole)] has been redetermined at low temperature in the correct space group [I23, a = 18.849 (1) A]. Structural analysis reveals a novel three-dimensional close-contact network of C60 molecules with tetrahedral holes similar to pristine C60.