Dinuclear neodymium and lanthanum bis(2,6-diisopropylphenyl) phosphate complexes bearing a hydroxide ligand: catalytic activity of the Nd complex in 1,3-diene polymerization

2018 ◽  
Vol 74 (6) ◽  
pp. 673-682 ◽  
Author(s):  
Mikhail E. Minyaev ◽  
Sof'ya A. Korchagina ◽  
Alexander N. Tavtorkin ◽  
Andrei V. Churakov ◽  
Ilya E. Nifant'ev
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Bonds ◽  
Molar Ratio ◽  
Vacuum Drying ◽  
Water Molecules ◽  
Nmr Studies ◽  
Space Groups ◽  
Phosphate Complex ◽  
Hydroxide Anion ◽  
Isoprene Polymerization

The reactions of K[(2,6-iPr2C6H3-O)2POO] either with LaCl3(H2O)7 or with Nd(NO3)3(H2O)6 in a 3:1 molar ratio, followed by vacuum drying and recrystallization from alkanes, have led to the formation of diaquapentakis[bis(2,6-diisopropylphenyl) phosphato]-μ-hydroxido-dilanthanum hexane disolvate, [La2(C24H34O4P)5(OH)(H2O)2]·2C6H14, (1)·2(hexane), and tetraaquatetrakis[bis(2,6-diisopropylphenyl) phosphato]-μ-hydroxido-dineodymium bis(2,6-diisopropylphenyl) phosphate heptane disolvate, [Nd2(C24H34O4P)4(OH)(H2O)4]·2C6H14, (2)·2(heptane). The compounds crystalize in the P21/n and P\overline{1} space groups, respectively. The diaryl-substituted organophosphate ligand exhibits three different coordination modes, viz. κ2 O,O′-terminal [in (1) and (2)], κO-terminal [in (1)] and μ2-κ1 O:κ1 O′-bridging [in (1) and (2)]. Binuclear structures (1) and (2) are similar and have the same unique Ln2(μ-OH)(μ-OPO)2 core. The structure of (2) consists of an [Nd2{(2,6-iPr2C6H3-O)2POO}4(OH)(H2O)4]+ cation and a [(2,6-iPr2C6H3-O)2POO]− anion, which are bound via four intermolecular O—H...O hydrogen bonds. The molecular structure of (1) displays two O—H...O hydrogen bonds between OH/H2O ligands and a κ1 O-terminal organophosphate ligand, which resembles, to some extent, the `free' [(2,6-iPr2C6H3-O)2POO]− anion in (2). NMR studies have shown that the formation of (1) undoubtedly occurs due to intramolecular hydrolysis during vacuum drying of the aqueous La tris(phosphate) complex. Catalytic experiments have demonstrated that the presence of the coordinated hydroxide anion and water molecules in precatalyst (2) substantially lowered the catalytic activity of the system prepared from (2) in butadiene and isoprene polymerization compared to the catalytic system based on the neodymium tris[bis(2,6-diisopropylphenyl) phosphate] complex, which contains neither OH nor H2O ligands.

The effect of partial methylation of the glycine amino group on crystal structure inN,N-dimethylglycine and its hemihydrate

2012 ◽  
Vol 68 (8) ◽  
pp. o283-o287 ◽  
Author(s):  
Vasily S. Minkov ◽  
Elena V. Boldyreva
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Water Molecules ◽  
Amino Group ◽  
Asymmetric Unit ◽  
Partial Methylation ◽  
Space Groups ◽  
Carboxylate Groups ◽  
Anhydrous Compound ◽  
Additional Hydrogen

N,N-Dimethylglycine, C4H9NO2, and its hemihydrate, C4H9NO2·0.5H2O, are discussed in order to follow the effect of the methylation of the glycine amino group (and thus its ability to form several hydrogen bonds) on crystal structure, in particular on the possibility of the formation of hydrogen-bonded `head-to-tail' chains, which are typical for the crystal structures of amino acids and essential for considering amino acid crystals as mimics of peptide chains. Both compounds crystallize in centrosymmetric space groups (PbcaandC2/c, respectively) and have twoN,N-dimethylglycine zwitterions in the asymmetric unit. In the anhydrous compound, there are no head-to-tail chains but the zwitterions formR44(20) ring motifs, which are not bonded to each other by any hydrogen bonds. In contrast, in the crystal structure ofN,N-dimethylglycinium hemihydrate, the zwitterions are linked to each other by N—H...O hydrogen bonds into infiniteC22(10) head-to-tail chains, while the water molecules outside the chains provide additional hydrogen bonds to the carboxylate groups.

scholarly journals Crystal structure of the new hybrid material bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate

2015 ◽  
Vol 71 (11) ◽  
pp. 1384-1387
Author(s):  
Marwen Chouri ◽  
Habib Boughzala
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Molar Ratio ◽  
Water Molecules ◽  
Site Symmetry ◽  
Two Dimensional ◽  
Slow Evaporation ◽  
Solution Ph

The title compound bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate, (C6H14N2)2[Bi2Cl10]·2H2O, was obtained by slow evaporation at room temperature of a hydrochloric aqueous solution (pH = 1) containing bismuth(III) nitrate and 1,4-diazabicyclo[2.2.2]octane (DABCO) in a 1:2 molar ratio. The structure displays a two-dimensional arrangement parallel to (100) of isolated [Bi2Cl10]4−bioctahedra (site symmetry -1) separated by layers of organic 1,4-diazoniabicyclo[2.2.2]octane dications [(DABCOH2)2+] and water molecules. O—H...Cl, N—H...O and N—H...Cl hydrogen bonds lead to additional cohesion of the structure.

Hydrate von Li3VO4: Synthese und Strukturchemie / Hydrates of Li3VO4: Synthesis and Structural Chemistry

2007 ◽  
Vol 62 (10) ◽  
pp. 1235-1245 ◽  
Author(s):  
Simone Schnabel ◽  
Caroline Röhr
Keyword(s):  
Hydrogen Bonds ◽  
Building Blocks ◽  
Water Molecules ◽  
Space Group ◽  
Space Groups ◽  
Monoclinic Form ◽  
Lithium Sulfide ◽  
3D Network ◽  
Coordination Spheres ◽  
A Chain

Stoichiometric hydrates of Li3VO4, the hexahydrate and two polymorphs of the octahydrate, were prepared by evaporation of alkaline aqueous solutions 1 molar in LiOH and 0.5 molar in the metavanadate LiVO3 at r. t. with or without the addition of Lithium sulfide, i. e. at different pH values. Their crystal structures have been determined and refined using single crystal X-ray data; all lithium and hydrogen atom positions were localised and refined without contraints. All three title compounds crystallise in non-centrosymmetric space groups. The water molecules belong to the tetrahedral coordination spheres of the Li cations, i. e. they are embedded as water of coordination exclusively. The tetrahedral orthovanadate(V) anions VO3−4 and the LiO4 tetrahedra are connected via common O corners to form building units which are further held together by strong, nearly linear hydrogen bonds. The hexahydrate Li3VO4 ・ 6H2O (space group R3, a = 962.9(2), c = 869.2(2) pm, Z = 3, R1 = 0.0260) contains isolated orthovanadate(V) anions VO3−4 surrounded by a 3D network of cornersharing Li(H2O)4 tetrahedra forming rings of three, seven and eight units. The water molecules are ‘isolated’ in the sense that no hydrogen bonds are formed between water molecules. The octahydrate is dimorphous: The triclinic polymorph of Li3VO4 ・ 8H2O (space group P1, a = 592.6(2), b = 651.3(2), c = 730.2(4) pm, α = 89.09(2), β = 89.43(2), γ = 88.968(12)°, Z = 1, R1 = 0.0325) contains two types of chains of tetrahedra: One consists of corner-sharing Li(H2O)4 tetrahedra only, the second one is formed by alternating LiO4 and VO4 tetrahedra, also sharing oxygen corners. Only one water molecule is ‘isolated’, the other seven form a branched fragment of a chain with hydrogen bonds between them. In the monoclinic form of Li3VO4・8H2O (space group Pc, a = 732.6(1), b = 653.7(1), c = 1292.9(3) pm, β = 112.21(1)°, Z = 2, R1 = 0.0289) a fragment of a chain of three LiO4 tetrahedra, two of which share a common edge, and one VO4 tetrahedron represent the formular unit. These building blocks are connected via hydrogen bonds formed by three ‘isolated’ water molecules and a chain fragment of five connected water molecules.

scholarly journals Bis(tetraethylammonium) oxalate dihydrate

2012 ◽  
Vol 68 (8) ◽  
pp. o2382-o2383 ◽  
Author(s):  
Timothy J. McNeese ◽  
Robert D. Pike
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Title Compound ◽  
Molar Ratio ◽  
Water Molecules ◽  
Oxalate Dihydrate ◽  
Carboxylate Groups ◽  
Graph Set ◽  
Oxalate Ion

The title compound, 2C8H20N+·C2O42−·2H2O, synthesized by neutralizing H2C2O4·2H2O with (C2H5)4NOH in a 1:2 molar ratio, is a deliquescent solid. The oxalate ion is nonplanar, with a dihedral angle between carboxylate groups of 64.37 (2)°. O—H...O hydrogen bonds of moderate strength link the O atoms of the water molecules and the oxalate ions into rings parallel to thecaxis. The rings exhibit the graph-set motifR44(12). In addition, there are weak C—H...O interactions in the crystal structure.

scholarly journals Crystal structure of 2-methyl-1H-imidazol-3-ium hydrogen oxalate dihydrate

2016 ◽  
Vol 72 (8) ◽  
pp. 1113-1115 ◽  
Author(s):  
Mouhamadou Birame Diop ◽  
Libasse Diop ◽  
Laurent Plasseraud ◽  
Hélène Cattey
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Oxalic Acid ◽  
Single Crystals ◽  
Molar Ratio ◽  
Methyl Groups ◽  
Water Molecules ◽  
Oxalate Dihydrate ◽  
Molecular Salt

Single crystals of the title molecular salt, C4H7N2+·HC2O4−·2H2O, were isolated from the reaction of 2-methyl-1H-imidazole and oxalic acid in a 1:1 molar ratio in water. In the crystal, the cations and anions are positioned alternately along an infinite [010] ribbon and linked together through bifurcated N—H...(O,O) hydrogen bonds. The water molecules of crystallization link the chains into (10-1) bilayers, with the methyl groups of the cations organized in an isotactic manner.

scholarly journals Crystal structure ofrac-(3aR,4S,5aR,6S,9R,10aS,10bR)-3a,5a,9-trimethyltetradecahydro-6,9-epoxycyclohepta[e]inden-4-ol monohydrate

2015 ◽  
Vol 71 (9) ◽  
pp. o690-o691 ◽  
Author(s):  
Andreas Schäfer ◽  
Christopher Golz ◽  
Hans Preut ◽  
Carsten Strohmann ◽  
Martin Hiersemann
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Organic Molecules ◽  
Membered Ring ◽  
Methyl Groups ◽  
Water Molecules ◽  
Asymmetric Unit ◽  
Relative Configuration ◽  
Space Groups ◽  
A Chain

The title hydrate, C17H28O2·H2O, was synthesized in order to determine the relative configuration of the tetracyclic framework. The fused 5,6,7-tricarbocyclic core exhibits an entirecis-annulation, featuring a 1,4-cis-relation of the angular methyl groups in the six-membered ring. The oxa bridge of the epoxycycloheptane moiety is oriented towards the concave face of the boat-shaped molecule, whereas the angular methyl groups are directed towards the convex face. The asymmetric unit of the crystal contains two nearly identical formula units, which are relatedviaa pseudo-centre of symmetry. The structure could be solved in the space groupsI-4 andI41/a. The refinement in the acentric space group, however, gave significantly better results and these are used in this paper. O—H...O hydrogen bonds are observed between the organic molecules, between the organic molecules and the water molecules, and between the water molecules, forming a chain along thec-axis direction.

scholarly journals Crystal structures of catena-poly[[μ-aqua-diaqua(μ3-2-methylpropanoato-κ4 O:O,O′:O′)calcium] 2-methylpropanoate dihydrate], catena-poly[[μ-aqua-diaqua(μ3-2-methylpropanoato-κ4 O:O,O′:O′)strontium] 2-methylpropanoate dihydrate] and catena-poly[[μ-aqua-diaqua(μ3-2-methylpropanoato-κ4 O:O,O′:O′)(calcium/strontium)] 2-methylpropanoate dihydrate]

2020 ◽  
Vol 76 (10) ◽  
pp. 1684-1688
Author(s):  
Erika Samolová ◽  
Jan Fábry
Keyword(s):  
Solid Solution ◽  
Hydrogen Atom ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Mirror Plane ◽  
Water Molecules ◽  
Space Groups ◽  
Positional Disorder ◽  
Carboxylate Groups ◽  
Additional Water

The crystal structures of catena-poly[[μ-aqua-diaqua(μ3-2-methylpropanoato-κ4 O:O,O′:O′)calcium] 2-methylpropanoate dihydrate], {[Ca(C4H7O2)(H2O)3](C4H7O2)·2H2O} n , (I), catena-poly[[μ-aqua-diaqua(μ3-2-methylpropanoato-κ4 O:O,O′:O′)strontium] 2-methylpropanoate dihydrate], {[Sr(C4H7O2)(H2O)3](C4H7O2)·2H2O} n , (II), and catena-poly[[μ-aqua-diaqua(μ3-2-methylpropanoato-κ4 O:O,O′:O′)(calcium/strontium)] 2-methylpropanoate dihydrate], {[(Ca,Sr)(C4H7O2)(H2O)3](C4H7O2)·2H2O} n , (III), are related. (III) can be considered as an Sr-containing solid solution of (I), with Ca2+ and Sr2+ occupationally disordered in the ratio 0.7936 (16):0.2064 (16). (I)/(III) and (II) are homeotypic with different space groups of Pbca and Cmce, respectively. All the title crystal structures are composed of hydrophilic sheets containing the cations, carboxylate groups as well as water molecules. The hydrophobic layers, which consist of 2-methylpropanoate chains, surround the hydrophilic sheets from both sides, thus forming a sandwich-like structure extending parallel to (001). The cohesion forces within these sheets are the cation–oxygen bonds and O—H...O hydrogen bonds of moderate strength. Stacking of these sandwiches along [001] is consolidated by van der Waals forces. The structures contain columns defined by the cation–oxygen interactions in which just one symmetry-independent 2-methylpropanoate anion is included, together with three water molecules. These molecules participate in an irregular coordination polyhedron composed of eight O atoms around the cation. Additional water molecules as well as the second 2-methylpropanoate anion are not part of the coordination sphere. These molecules are connected to the above-mentioned columns by O—H...O hydrogen bonds of moderate strength. In (II), the Sr2+ cation, two of the coordinating water molecules and both anions are situated on a mirror plane with a concomitant positional disorder of the 2-methylpropyl groups; the non-coordinating water molecule also shows positional disorder of its hydrogen atom.

Adducts of meso and racemic 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane with trigonally trisubstituted benzene carboxylic acids: supramolecular structures in one and two dimensions

2000 ◽  
Vol 56 (6) ◽  
pp. 1054-1062 ◽  
Author(s):  
Colin J. Burchell ◽  
George Ferguson ◽  
Alan J. Lough ◽  
Christopher Glidewell
Keyword(s):  
Hydrogen Bonds ◽  
Carboxylic Acids ◽  
Supramolecular Structure ◽  
Two Dimensions ◽  
Supramolecular Structures ◽  
Acid Water ◽  
Water Molecules ◽  
One Dimensional ◽  
Space Groups

The meso and racemic forms of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, C16H36N4 (tet-a and tet-b, respectively), form adducts with trigonally trisubstituted benzene carboxylic acids; tet-a–3,5-dinitrobenzoic acid (1/2) (1), tet-a–5-hydroxyisophthalic acid–water (1/1/1) (3) and tet-b–5-hydroxyisophthalic acid–water (1/1/1) (4) are all salts, [C16H38N4]2+·2[C7H3N2O6]− (1) and [C16H38N4]2+·[C8H4O5]2−·H2O (3) and (4). The conformations of the [(tet-a)H2]2+ and [(tet-b)H2]2+ cations are entirely different: [(tet-a)H2]2+ is precisely centrosymmetric in (1) and approximately so in (3), while [(tet-b)H2]2+ has approximate C 2 symmetry in (4). In each salt the cation forms two intramolecular N—H...N and four intermolecular N—H...O hydrogen bonds. In (1) the supramolecular structure is one-dimensional, a C 2 2(13)[R 2 4(16)] chain of rings. Compounds (3) and (4) crystallize in space groups P212121 and P21/c, respectively, but the supramolecular structures are very similar: in each, the anions and the water molecules form a C(7)[R 3 3(13)] chain of rings, generated in (3) by a 21 axis and in (4) by a glide plane. These chains are linked, in both (3) and (4), by cations to form sheets. Adjacent meso cations in (3) are related by a 21 axis and adjacent chiral cations in (4) are related by a glide plane.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

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