Transmetalation reactions with nitrogen-containing "pincer"-class ligands on platinum(II) centers

2001 ◽  
Vol 79 (5-6) ◽  
pp. 709-718 ◽  
Author(s):  
Martin Albrecht ◽  
Stuart L James ◽  
Nora Veldman ◽  
Anthony L Spek ◽  
Gerard van Koten
Keyword(s):  
Ligand Binding ◽  
Platinum Complexes ◽  
Binding Mode ◽  
Unit Cell ◽  
The Other ◽  
Pincer Ligand ◽  
X Ray ◽  
Spectroscopic Analyses ◽  
Structure Determinations ◽  
Independent Molecules

The transmetalation reaction of the aryllithium compound [Li(NCN)]2 (NCN is the monoanionic "pincer" ligand [C6H3(CH2NMe2)2-2,6]-) with the cyclometalated arylplatinum complex [PtCl(NCN)] afforded the bisaryl platinum(II) complex [Pt(NCN)2] (3) containing one η3-N,C,N-terdentate and the other η1-C-monodentate-bonded pincer ligand. Spectroscopic analyses on 3 suggest that η3 to η1 interconversion of the ligand binding mode (or vice versa) is inhibited. Two independent X-ray structure determinations on crystals of 3 revealed the existence of a rare polymorph containing one and three crystallographically independent molecules, respectively, in the unit cell. A similar transmetalation reaction with lithium and platinum complexes containing heteroleptic NCNRR' ligands (NCNRR' is [C6H3(CH2NRR')-2,6]- with R = R' = Me or R = Me, R' = Et) pointed to the formation of a heterodinuclear cationic bisaryl platinum lithium species as an intermediate of a preequilibrium to the final transmetalation products, involving, rapid transcyclometalation (TCM) reactions. These TCM reactions comprise the exchange of the monoanionic NCNRR' ligands between the platinum(II) and lithium centers. A consequence of the latter properties is that the strong Pt—N bonds in [PtX(NCN)] complexes are considerably weakened by the presence of Li+ cations.Key words: transmetalation, transcyclometalation (TCM), platinum, bisaryl complex, polymorphism.

Isomers of Diformyl[2.2]paracyclophane; X-Ray Structure Determinations of the Pseudo-ortho Isomer and Two Polymorphs of the Pseudo-meta Isomer

2011 ◽  
Vol 66 (7) ◽  
pp. 705-710
Author(s):  
Peter G. Jones ◽  
Ina Dix ◽  
Mihaela Negru ◽  
Dieter Schollmeyer
Keyword(s):  
General Position ◽  
The Other ◽  
Independent Molecule ◽  
Space Group ◽  
X Ray ◽  
Ortho Isomer ◽  
Layer Structures ◽  
Structure Determinations ◽  
Independent Molecules ◽  
Meta Isomer

Pseudo-ortho- or 4,16-diformyl[2.2]paracyclophane (1) and two polymorphs of pseudo-meta- or 4,13-diformyl[2.2]paracyclophane (2) all display the usual features of [2.2]paracyclophane strain (lengthened C-C bonds and widened C-C(sp3)-C angles in the bridges, narrower sp2 ring angles at the bridgehead atoms, and flattened boat conformations of the rings). All bulk samples were racemates. Polymorph 2a crystallizes in space group P21/n with one molecule in a general position, whereas 2b crystallizes in space group C2 with two independent molecules, each with crystallographic twofold symmetry. All three molecules of 2 are different rotamers with respect to the formyl groups; in 2a one is endo and one exo to the neighbouring bridge, whereas in 2b both formyls are exo in one molecule and endo in the other. In all compounds, the packing patterns are preponderantly associated with C-H・ ・ ・O contacts. In 1 the molecules are connected to form tubes parallel to the short a axis. 2a consists of two interconnected layer structures. One is parallel to (100) and involves chains of molecules parallel to [01̄1]; the other is parallel to (001) and involves chains of molecules parallel to the b axis. 2b consists of two hexagonal layers, one for each independent molecule, parallel to (001). One layer contains bifurcated (C-H・ ・ ・ )2O systems, whereas the single H・ ・ ・O interactions in the other are long and markedly bent.

Crystal Structures of Seven Terephthaldiamide Derivatives

2002 ◽  
Vol 57 (8) ◽  
pp. 914-921 ◽  
Author(s):  
P. G. Jones ◽  
J. Ossowski ◽  
P. Kus
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Layer Structure ◽  
Inversion Symmetry ◽  
Asymmetric Unit ◽  
X Ray ◽  
Layer Structures ◽  
Structure Determinations ◽  
Independent Molecules

N,N′-Dibutyl-terephthaldiamide (1), N,N′-dihexyl-terephthaldiamide (2), N,N′-di(tert-butyl)- terephthaldiamide (3), N,N,N′,N′-tetrabutyl-terephthaldiamide (4), 1,1′-terephthaloylbis- pyrrolidine (5), 1,1′-terephthaloyl-bis-piperidine (6), and 4,4′-terephthaloyl-bis-morpholine (7) have been synthesised and physicochemically characterised. The X-ray structure determinations reveal imposed inversion symmetry for compounds 1-6; compound 3 has two independent molecules with inversion symmetry in the asymmetric unit. Compounds 1-3 form classical hydrogen bonds of the type N-H···O=C, leading to a ribbon-like arrangement of molecules (1 and 2) or a layer structure (3). Compound 3 also displays a very short C-H···O interaction, a type of hydrogen bond that is also observed in compounds 4-7, which lack classical donors; thereby compounds 4-6 form layer structures and 7 a complex threedimensional network.

Structural Systematics of 2/4-Nitrophenoxide Complexes of Closed-Shell Metal Ions. VII Acid Salts of the 4-Nitrophenoxides of Group 2

1998 ◽  
Vol 51 (8) ◽  
pp. 785 ◽  
Author(s):  
Jack M. Harrowfield ◽  
Raj Pal Sharma ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Room Temperature ◽  
Calcium Salt ◽  
Three Dimensional ◽  
Closed Shell ◽  
The Other ◽  
X Ray ◽  
C 23 ◽  
Structure Determinations ◽  
Group 2 ◽  
Acid Salts

Room-temperature single-crystal X-ray structure determinations are recorded for a number of Group 2 4-nitrophenoxide acid salts, variously hydrated M(4-np)2.x(4-npH).yH2O. Ca(4-np)2.2(4-npH).8H2O is monoclinic, P 21/n, a 30·52(1), b 10·027(1), c 23·65(2) Å, β 116·3(5)°, Z = 8, conventional R on |F| being 0·058 for No 5092 independent ‘observed’ (I > 3s(I)) reflections. Sr(4-np)2.2(4-npH).8H2O, based on a subcell of the former, is monoclinic, P 21/c, a 15·576(5), b10·081(6), c 24·20(2) Å, β 117·99(5)° , Z = 4, R 0·054 for No 2908. Ba(4-np)2.2(4-npH).4H2O is orthorhombic, Fdd2, a 28·01(1), b 19·90(1), c 10·692(7)Å, Z = 8, R 0·028 for No 1967. The strontium array (and that of the calcium salt developed from it) may be represented as [(H2O)6Sr(4-npH.4-np)] (4-npH.4-np), a neutral ligand being unsymmetrically chelated to the strontium through the nitro group, with a quasi-parallel counter ion hydrogen-bonded to it by phenoxide confrontation. The other two 4-np residues make up a similar phenoxide-confronting pair (4-npH.4-np), the hydrogen being more intimately associated with one moiety. The barium salt is also an interesting array: the 10-coordinate barium lies on a crystallographic 2 axis, in an environment of two pairs of symmetry-related nitro-chelating ligand anions, and a pair of nitro-O coordinating neutral 4-npH ligands; the whole [(H2O)4Ba(4-np)2(4-npH)2] array may be envisaged as a single neutral (super)molecule. Hydrogen bonds between confronting phenoxides of the neutral 4-npH components of the parent and the 4-np- components of neighbouring molecules link the whole into a three-dimensional array.

Polypyridines, Picrates, Lanthanides: A Plethora of Stacks?

2020 ◽  
Vol 73 (6) ◽  
pp. 529
Author(s):  
Eric J. Chan ◽  
Simon A. Cotton ◽  
Jack M. Harrowfield ◽  
Brian W. Skelton ◽  
Alexandre N. Sobolev ◽  
...  
Keyword(s):  
Nitro Group ◽  
The Other ◽  
Molar Ratio ◽  
Lanthanide Ion ◽  
X Ray ◽  
The Third ◽  
Group Oxygen ◽  
Structure Determinations ◽  
Lighter Lanthanides ◽  
Trigonal Prismatic

Reactions of the lanthanide(iii) picrates (picrate=2,4,6-trinitrophenoxide=pic) with 1,10-phenanthroline (phen) and 2,2′:6′,2′′-terpyridine (terpy) in a 1:2 molar ratio have provided crystals suitable for X-ray structure determinations in instances predominantly involving the lighter lanthanides. In all, the aza-aromatic ligands chelate the lanthanide ion, none being found as ‘free’ ligands within the lattice. The complexes of 1,10-phenanthroline have been characterised in two forms, one unsolvated (Ln=La, Sm, Eu; monoclinic, C2/c, Z 8), one an acetonitrile monosolvate (Ln=Gd; monoclinic, P21/a, Z 4), the latter being the only previously known form (with Ln=La). In both forms, the LnIII is nine-coordinate, in an approximately tricapped trigonal-prismatic environment, with two picrate ligands chelating through phenoxide and 2-nitro group oxygen atoms, the third being bound through phenoxide-O only. The 2,2′:6′,2′′-terpyridine complexes, all acetonitrile monosolvates defined for Ln=La, Gd, Er, and Y (monoclinic, C2/c, Z 4), are ionic, one picrate having been displaced from the primary coordination sphere. For Ln=La, the two bound picrates are again chelating, making the LaIII 10-coordinate in a distorted bicapped square-antiprismatic environment but in the other species they are bound through phenoxide-O only, making the LnIII ions eight-coordinate in a distorted square-antiprismatic environment. Stacked arrays of the ligands can be found in both series of complexes, with intramolecular picrate–picrate and picrate–aza-aromatic stacks being prominent features.

scholarly journals Powder X-ray diffraction of trimethoprim Form I, C14H18N4O3

2020 ◽  
Vol 35 (1) ◽  
pp. 69-70
Author(s):  
Jerry Hong ◽  
Joseph T. Golab ◽  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
The United States ◽  
Unit Cell ◽  
Cell Length ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Determinations ◽  
Unit Cell Length

Trimethoprim crystallizes in the triclinic space group P-1 (#2) with a = 10.5085(3), b = 10.5417(2), c = 8.05869(13) Å, α = 101.23371(21), β = 112.1787(3), γ = 112.6321(4)°, V = 743.729 Å3, and Z = 2. A reduced cell search in the Cambridge Structural Database yielded three previous structure determinations, using data collected at 100 K, 173 K, and room temperature. In this work, the sample was ordered from the United States Pharmacopeial Convention (USP) and analyzed as-received. The room temperature (295 K) crystal structure was refined using synchrotron (λ = 0.412826 Å) powder diffraction data and optimized using density functional theory techniques. We found similar hydrogen bonding patterns with the previous determinations. In addition, we identified two C–H⋯O hydrogen bonds, which also contribute to the crystal energy. When comparing the previously reported trimethoprim structure determinations, the unit cell length lattice parameters were found to contract at lower temperatures, particularly 100 K. All structures show reasonable agreement, with unit cell length differences ranging between 0.05 and 0.15 Å. The diffraction data for this study were collected on beamline 11-BM at the Advanced Photon Source, and the powder X-ray diffraction pattern of the compound has been submitted to ICDD® for inclusion in the Powder Diffraction File™ (PDF®).

Study of Garnets by ALCHEMI

2001 ◽  
Vol 7 (S2) ◽  
pp. 358-359
Author(s):  
János L. Lábár ◽  
Lajos Tόth ◽  
István Dόdony ◽  
Jerzy Morgiel
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
High Sensitivity ◽  
Unit Cell ◽  
Previous Literature ◽  
The Other ◽  
Axial Orientation ◽  
Partial Substitution ◽  
X Ray ◽  
Oxygen Atoms

Garnets were one of the first materials in which an occupation of separate lattice sites by different atomic species was determined with an ALCHEMI technique proposed by Spence and Tafto in l982. The reason of so much interest in this material was twofold, i.e. first its known high sensitivity of X-ray generation depending on orientation especially in the axial orientation and second its complicated crystal structure allowing different atomic arrangements in the unit cell depending on its chemical composition. The dodecahedral (X), octahedral (Y) and tetrahedral (Z) sites between the relatively large oxygen atoms can be filled with a variety of small cations in accordance with the formula X3Y2Z3O12. Partial substitution of one cation with another is common in this structure. The results presented in the previous literature indicated that ALCHEMI can only separate the Y-sites from the sum of the other two (X+Z), while the latter has to remain unresolved.

One-dimensional ribbons of solvated Ag sulfonates

1999 ◽  
Vol 77 (3) ◽  
pp. 313-318 ◽  
Author(s):  
George KH Shimizu ◽  
Gary D Enright ◽  
Gabriela S Rego ◽  
John A Ripmeester
Keyword(s):  
Coordination Polymer ◽  
Single Crystal ◽  
The Other ◽  
Monoclinic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
One Dimensional ◽  
X Ray ◽  
Structure Determinations

Single crystal X-ray structure determinations of two solvated silver sulfonates have been obtained and these compounds have been shown to adopt infinite one-dimensional motifs. {AgOTs(MeCN)}[Formula: see text] (OTs = p-toluenesulfonate) crystallizes in the monoclinic space group, P21, a = 8.4278(5) Å, b = 5.7413(3) Å, c = 12.1057(7) Å, β = 109.24(1)°. {Ag(NDSA)(MeCN)2(H3O)(H2O)2}[Formula: see text] (NDSA = 1,5-naphthalenedisulfonate) crystallizes in the triclinic space group, P[Formula: see text], a = 8.3407(4) Å, b = 10.4374(5) Å, c = 12.3399(6) Å, α = 101.941(8)°, β = 109.24(1)°, γ = 102.190(8)°. Despite one compound containing a monosulfonate and the other a disulfonate, both complexes form infinite one-dimensional arrays.Key words: silver, sulfonates, coordination polymer.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LIII. Synthesis and Structural Characterization of Binuclear μ,μ'-Dichloro-, Dibromo and Diiodo-bis[(pyridine)(triphenylphosphine)copper(I)] Complexes, and Their Pyridine-4-carbonitrile Analogues

1989 ◽  
Vol 42 (6) ◽  
pp. 913 ◽  
Author(s):  
LM Engelhardt ◽  
PC Healy ◽  
JD Kildea ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Structural Characterization ◽  
Lewis Base ◽  
The Other ◽  
X Ray ◽  
Structure Determinations ◽  
M Phase ◽  
And Inversion ◽  
Iodide Single Crystal

Mixed base pyridine (py)/triphenylphosphine adducts of the copper(1) halides, CuX, have been synthesized for 1 : 1 : 1 stoichiometry for X = chloride and iodide; single-crystal X-ray structure determinations of these show them to be isomorphous and isostructural with that of the bromide recorded elsewhere, being �,�′- dihalo-bridged dimers , [(PPh3)( py )CuX2Cu( py )(PPh3)], monoclinic, C2/c, a ≈ 26.2, b ≈ 14.3, c ≈ 11 .2 � , β ≈ 95, Z = 4 dimers. The bromide has been isolated as a new monoclinic C 2/m polymorph, a 11 .279(8), b 14.268(6), c 13.858(4) �, β 109.33(6)�, Z=4 dimers, and details of its structure are also recorded. The structures of their pyridine-4-carbonitrile (pycn) analogues have also been determined and found to be also binuclear, with no cyano-copper interactions; these also are an isomorphous, isostructural series, monoclinic P21/n, a ≈ 15.4, b ≈ 8.1, c ≈ 17.9 � , β ≈ 101 �, Z = 2 dimers. In each series of dimers, one half of the dimer is crystallographically independent, the generators of the other half being twofold rotor (C2/c phase), mirror (C2/m phase) and inversion centre (P21/n phase) respectively.

Tris [(trimethylsilyl)oxy] antimony

1994 ◽  
Vol 49 (7) ◽  
pp. 855-858 ◽  
Author(s):  
Michael Baier ◽  
Klaus Angermaier ◽  
Hubert Schmidbaur
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Gas Phase ◽  
Structure Determination ◽  
Spectroscopic Data ◽  
Mass Spectrometric ◽  
Unit Cell ◽  
The Other ◽  
X Ray ◽  
Trigonal Bipyramidal

Abstract Tris[(trimethylsilyl)oxy]antimony (Sb(OSiMe3)3, 1) has been prepared from SbCl3 and 3 equiv. of LiOSiMe3 in diethylether. According to mass spectrometric and NMR spectroscopic data, 1 appears to be a monomer in solution and in the gas phase. Dimerisation occurs, however, in the solid state as verified by an X-ray crystal structure determination. The unit cell contains three crystallographically independent monomers, two of which form one type of dimer, while the other is part of a centrosymmetrical dimer. In both types of dimers two Sb atoms are connected via two OSiMe3 groups to form distorted Sb2O2-squares. Together with the remaining 4 OSiMe3 groups and the two stereochemically active lone pairs, each Sb exhibits a trigonal bipyramidal coordination.

Structural Systematics of Rare Earth Complexes. XIII (‘Maximally’) Hydrated (Heavy) Rare Earth Nitrates

1999 ◽  
Vol 52 (6) ◽  
pp. 497 ◽  
Author(s):  
David L. Kepert ◽  
Peter C. Junk ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Rare Earth ◽  
The Other ◽  
Water Molecules ◽  
Bidentate Ligands ◽  
X Ray ◽  
Rare Earth Nitrates ◽  
Triclinic Phase ◽  
Cell Dimensions ◽  
Structure Determinations ◽  
Coordinated Water

Room-temperature single-crystal X-ray structure determinations are known for a number of ‘maximally hydrated" nitrates of, in particular, the lighter lanthanoid elements; in all cases, all nitrates coordinate as O,O′-bidentate ligands so that the series may be represented at the outset as Ln(O2NO)3.x H2O. Two distinct triclinic P 1 hexahydrate phases of similar cell dimensions are recognized, the most distinctive distinguishing feature being that in the La, Ce phase the 11-coordinate Ln is surrounded by three O,O′-bidentate nitrate and five O-unidentate water molecule ligands; the domain of the other, with four coordinated water molecules, extends from Ln = Pr to Ln = Dy (inclusive of Y). At local ambience, we have crystallized heavier members of the series as pentahydrates, isomorphous with the previously characterized Ln = Eu example, also containing a molecule of the form [Ln(O2NO)3(OH2)4] (with a molecule of water of crystallization), but a different stereoisomer to that found in the Ln = Pr(-)Dy array. Structure determinations are recorded for Ln = Dy, Er, Yb, conventional R on |F| 0·042, 0·034, 0·029 for No = 3858, 3980, 3935 independent ‘observed’ (I > 3σ(I)) diffractometer reflections. For Ln = Lu a new tetrahydrate phase is described, monoclinic P21/n, a 7·379(7), b 10·364(5), c 14·26(1) Å, β 96·09(7)°, Z = 4, R 0·048 for No 2324, together with a new triclinic P 1 trihydrate, a 12·591(4), b 12·144(3), c 7·355(2) Å, α 80·22(2), β 77·68(3), γ 62·30(2)°, Z = 4, R 0·051 for No 4552. In both of the latter, Lu is nine-coordinate, with three bidentate nitrate groups and three coordinated water molecules; remarkably, the two independent molecules of the asymmetric unit in the triclinic phase are distinct isomers, one having the water molecules fac, derivative of the 10-coordinate array of the Pr(-)Yb series with quasi-3 symmetry, while the other, like that in the monoclinic phase, is mer.

Sign in / Sign up

Export Citation Format

Share Document