Sylvain Lecocq

Tin dioxide thin films from Sn(IV) modified alkoxides — synthesis and structural characterization of Sn(OEt)2(η2-acac)2 and Sn4(μ3-O)2(μ2-OEt)4(OEt)6(η2-acac)2

SnO 2 or doped SnO 2 thin films can be used as transparent conductors in various optoelectronic devices such as screens or solar cells. They usually present high optical transmittance, low resistivity and high chemical and mechanical stability. The synthesis and single crystal X-ray diffraction analysis of new tin (IV) modified alkoxides Sn(OEt) 2 (η 2 -acac) 2 ( 1 ) and Sn 4 (μ 3 -O) 2 (μ 2 -OEt) 4 (OEt) 6 (η 2 -acac) 2 ( 2 ) (acacH=2,4 pentanedione) are reported. 1 crystallizes in the monoclinic system (space group P 2 1 / n ) while 2 crystallizes in the triclinic system (space group P 1). The asymmetric unit of the molecular species Sn(OEt) 2 (η 2 -acac) 2 contains two monomers which are slightly different. Sn 4 (μ 3 -O) 2 (μ 2 -OEt) 4 (OEt) 6 (η 2 -acac) 2 is a tetranuclear species in which Sn atoms are connected together by two triply bridging oxo ligands and four bridging ethoxo groups. Six terminal ethoxo groups and two chelating β-diketonato ligands are completing the coordination of the metal atoms. Their behaviour towards hydrolysis–condensation reactions is discussed.

Complexation of Cobalt(II) at the Upper Rim of Two New Calix[4]arene/Bipyridine-Based Podands

Introduction of one or two 2,2′-bipyridine units at the upper rim of the calix[4]arene platform was performed by means of the Wittig reaction. The resulting alkenes were hydrogenated to give two new bipyridyl-based calixarene podands, which were studied as ligands for CoII cation. The mono-bipyridyldichlorocobalt complex was notably fully characterised by 1H-NMR and X-ray crystal structure analyses, which confirmed the tetrahedral coordination mode involving the bipyridyl subunit and the two chlorine atoms around the cobalt centre.

Complexation ofp-xylene withp-isopropylcalix[4]arene: Crystal structures and thermal analysis of the empty form and the (1 : 1) and (2 : 1) complexes

This paper concerns inclusion complexes of thep-isopropylcalix[4]arene host withp-xylene as guest. It is shown that from a saturated solution inp-xylene, the macrocycle gives a 1 : 1 complex; on heating, the 1 : 1 complex is transformed into a 2: 1 complex, and then into the empty macrocycle. The compounds are studied by differential scanning calorimetry, thermogravimetry and X-ray powder diffraction; the three crystal structures are reported showing the arrangements of the macrocycles with and without their guests.

Crystal Structures of Two Calix[10]arenes Complexed with Neutral Molecules

Two calix[10]arenes were synthesized: the tert-butylcalix[10]arene (t-Bu-C10) and the detertbutylated analogue (H-C10). Both were crystallized from saturated solutions: t-Bu-C10 from a mixture of toluene and tetrahydrofuran (THF), H-C10 from acetone. In each case, complexes were obtained: H-C10, acetone 1:2 and t-Bu-C10, toluene, THF 1:2.5:0.5. The crystal structures of these twocomplexes and the different conformations of the macrocycles are presented here.For the first, the crystals are triclinic, space group Pmacr{1}, a = 9.037(2)Å, b = 11.447(2)Å, c = 15.197(3)Å, α = 80.79(3)Å, β = 84.96(3)°, γ = 88.60(3)°, V = 1545.7(5)Å3, Z = 1; the complex with t-Bu-C10 is orthorhombic, space group Fmm2, a = 32.211(6)Å, b = 32.289(7)Å, c = 12.179(2)Å, V = 12667(4)Å3, Z = 4. The complex from H-C10 shows a pleated loop conformation with H-bonds between acetone and hydroxylgroups. The complex from t-Bu-C10 shows several cavities, in the conesshaped by the phenol moieties and near the hydroxyl groups. The packingsare given for both crystals.

Insights in the sol–gel processing of Pb(Mg1/3Nb2/3)O3. The synthesis and crown structure of a new lead magnesium cluster: Pb6Mg12(μ-OAc)6(μ2,η2-OAc)18(μ3,η2-OC2H4OPri)12

The synthesis and molecular structure of a Pb-Mg bimetallic acetatoalkoxide (Pb-6,Mg-12( mu-OAc)(6)(mu(2), eta(2)-OAc)(18)(mu(3), eta(2)-OC2H4OPr1)(12), space group R-3, a = b = 30.032(2), c = 18.855(2) Angstrom, alpha = beta = 90degrees, gamma = 120degrees) are discussed in this article. This compound was isolated as an intermediate during the elaboration of Pb(Mg1/3Nb2/3)O-3 (PMN) using sol-gel process. It results from the reaction of a bimetallic Mg/Nb species with lead acetate in 2-isopropoxyethanol

Crystal and molecular structures ofp-(1,1,3,3-tetramethylbutyl)calix[5]arene and its 1 : 1 complex with toluene

A cyclic pentamer was obtained fromp-(1,1,3,3-tetramethylbutyl) phenol. It crystallizes from a mixture of acetone and toluene at room temperature giving a 1 : 1 complex with toluene (compound A), whereas at 50°C the empty form (compound B) is obtained. Crystals of A are orthorhombic, space groupPna21,a = 20.083(2),b = 12.936(6),c = 28,423(1) Å,Z = 4, finalR value = 0.067. The empty form, B, is monoclinicP21/c,a = 18.695(2),b = 11.673(5),c = 35.100(4) Å, β = 114.33(1),Z = 4, finalR value = 0.135. The macrocycle is in the cone conformation for both compounds; the toluene molecule lies in the cone as often found for calix[4]arenes.

p-tert-Butylcalix[5]arene: a New Synthetic Pathway and Crystal Structure of the N,N-Dimethylformamide Complex

The formation of p-tert-butylcalix[5]arene by the opening ofp-tert-butyldihomooxacalix [4]arene and the addition of a monomer has beenstudied. Various facets, including the effects of bases and the nature ofthe monomer added to the p-tert-butyldihomooxacalix[4]arene, have beeninvestigated. p-tert-Butylcalix[5]arene can be prepared in yields up to30%. The structure of its 1 : 2 complex with DMF has been determinedby X-ray crystallography. Crystals are triclinic, space group P¯1, a =1428.2(3) pm, b = 1837.3(3) pm, c = 1276.1(2) pm, α = 108.98(1)°,β = 105.02(2)°, γ = 95.21(1)°, Z = 2, D c = 1.059 kg m-3,final R value = 0.087. The macrocycle adopts a cone conformation, one guestenclosed inside the cavity, the other one outside.

Change of Conformation Induced by Complexation in p-tert-butyldihomooxacalix[4]arene

Abstract The crystal structure of p-tert-butyldihomooxacalix [4]arene is reported: Space group P21/c a = 16.855(2), b = 18.526(4), c = 13.175(3) A, β = 105.85(2)°. The conformation of the macrocycle is compared with the ones found for various complexes of the same calix-arene. Striking changes are observed; they concern the dimethyleneoxa bridge which exhibits a very asymmetric and nonplanar geometry in the uncomplexed molecule compared with the shape it presents in complexes. The calixarenic moiety of the molecule itself exhibits some changes in the depth of the bowl and in its symmetry.

Crystal and molecular structure of the (1 : 1) clathrate between a calix[4]arene containing onep-nitrophenol unit and toluene

Abstractp-(Methyl,tert-butyl, nitro,tert-butyl) calix[4]arene: toluene, C37H41NO6. C7H8,Mr = 687.87, triclinic,