scholarly journals The crystal structures of tetrakis(μ-n-butyrato-κ2O:O′)bis[bromidorhenium(III)] and tetrakis(μ-n-butyrato-κ2O:O′)bis[chloridorhenium(III)] acetonitrile disolvate

2015 ◽  
Vol 71 (12) ◽  
pp. 1480-1484
Author(s):  
Carly R. Reed ◽  
William W. Brennessel
Keyword(s):  
Crystal Structures ◽  
Close Contact ◽  
Solvent Molecule ◽  
Inversion Center ◽  
Carboxylate Ligands ◽  
Quadruple Bonds

The title complexes, [Re2Br2(O2CC3H7)4], (1), and [Re2(O2CC3H7)4Cl2]·2CH3CN, (2), both exhibit paddlewheel structures with four carboxylate ligands bridging two ReIIIatoms. The Re—Re distances are 2.2325 (2) and 2.2299 (3) Å, indicating quadruple bonds between the ReIIIatoms in each complex. Both complexes contain an inversion center at the mid-point of the Re—Re bond. The Re—Br bond [2.6712 (3) Å] in (1) is 0.1656 (6) Å longer than the Re—Cl distance [2.5056 (5) Å] of (2). In (2), the N atom of each co-crystallized acetonitrile solvent molecule is nearly equidistant between and in close contact with two carboxylate C atoms.

Homoleptic 2,2′-bipyridine metalates(–I) of iron and cobalt, one cocrystallized with an anthracene radical anion and the other with neutral anthracene

2014 ◽  
Vol 70 (8) ◽  
pp. 828-832
Author(s):  
William W. Brennessel ◽  
John E. Ellis
Keyword(s):  
Radical Anion ◽  
Complex Cation ◽  
Solvent Molecule ◽  
Inversion Center ◽  
Asymmetric Unit ◽  
Aromatic Donor ◽  
Donor Acceptor ◽  
Anthracene Molecule ◽  
Packing Arrangement ◽  
Solvent Molecules

Homoleptic 2,2′-bipyridine (bipy) metalates of iron and cobalt have been synthesized directly from the corresponding homoleptic anthracene metalates. In the iron structure, bis[([2.2.2]cryptand)potassium(I)] tris(2,2′-bipyridine)ferrate(–I) anthracene(–I), [K(C18H36N2O6)]2[Fe(C10H8N2)3](C14H10), the asymmetric unit contains one potassium complex cation in a general position, the Fe center and one and a half bipy ligands of the ferrate complex on a crystallographic twofold axis that includes the Fe atom, and one half of an anthracene radical anion whose other half is generated by a crystallographic inversion center. The cations and anions are well separated and the geometry about the Fe center is essentially octahedral. In the cobalt structure, ([2.2.2]cryptand)potassium(I) bis(2,2′-bipyridine)cobaltate(–I) anthracene hemisolvate tetrahydrofuran (THF) disolvate, [K(C18H36N2O6)][Co(C10H8N2)2]·0.5C14H10·2C4H8O, the asymmetric unit contains the cation, anion, and both cocrystallized THF solvent molecules in general positions, and one half of a cocrystallized anthracene molecule whose other half is generated by a crystallographic inversion center. The cation and anion are well separated and the ligand planes in the cobaltate anion are periplanar. Each anthracene molecule is midway between and is oriented perpendicular to a pair of symmetry-related bipy ligands such that aromatic donor–acceptor interactions may play a role in the packing arrangement. The lengths of the bonds that connect the bipy rings support the assertion that the ligands are bipy radical anions in the iron structure. However, in the case of cobalt, these lengths are between the known ranges for a bipy radical anion and a bipy dianion, and therefore no conclusion can be made from the crystallography alone. One cocrystallized THF solvent molecule in the cobalt structure was modeled as disordered over three positions with appropriate geometric and thermal restraints, which resulted in a refined component mass ratio of 0.412 (4):0.387 (3):0.201 (3).

scholarly journals Structure of a dinuclear cadmium complex with 2,2′-bipyridine, monodentate nitrate and 3-carboxy-6-methylpyridine-2-carboxylate ligands: intramolecular carbonyl(lone pair)...π(ring) and nitrate(π)...π(ring) interactions

2015 ◽  
Vol 71 (8) ◽  
pp. 890-894
Author(s):  
Juan Granifo ◽  
Sebastián Suarez ◽  
Ricardo Baggio
Keyword(s):  
Complex Molecule ◽  
Solvent Molecule ◽  
Lone Pair ◽  
Dinuclear Complex ◽  
Cadmium Complex ◽  
Nitrate Anion ◽  
Coordination Geometry ◽  
Complex Molecules ◽  
Carboxylate Ligands ◽  
Solvent Molecules

The centrosymmetric dinuclear complex bis(μ-3-carboxy-6-methylpyridine-2-carboxylato)-κ3N,O2:O2;κ3O2:N,O2-bis[(2,2′-bipyridine-κ2N,N′)(nitrato-κO)cadmium] methanol monosolvate, [Cd2(C8H6NO4)2(NO3)2(C10H8N2)2]·CH3OH, was isolated as colourless crystals from the reaction of Cd(NO3)2·4H2O, 6-methylpyridine-2,3-dicarboxylic acid (mepydcH2) and 2,2′-bipyridine in methanol. The asymmetric unit consists of a CdIIcation bound to a μ-κ3N,O2:O2-mepydcH−anion, anN,N′-bidentate 2,2′-bipyridine group and anO-monodentate nitrate anion, and is completed with a methanol solvent molecule at half-occupancy. The Cd complex unit is linked to its centrosymmetric image through a bridging mepydcH−carboxylate O atom to complete the dinuclear complex molecule. Despite a significant variation in the coordination angles, indicating a considerable departure from octahedral coordination geometry about the CdIIatom, the Cd—O and Cd—N distances in this complex are surprisingly similar. The crystal structure consists of O—H...O hydrogen-bonded chains parallel toa, further bound by C—H...O contacts alongbto form planar two-dimensional arrays parallel to (001). The juxtaposed planes form interstitial columnar voids that are filled by the methanol solvent molecules. These in turn interact with the complex molecules to further stabilize the structure. A search in the literature showed that complexes with the mepydcH−ligand are rare and complexes reported previously with this ligand do not adopt the μ-κ3coordination mode found in the title compound.

scholarly journals Di-μ-chlorido-bis{[2-(di-tert-butylphosphanyl)biphenyl-3-yl-κ2C3,P]palladium(II)} dichloromethane disolvate

2013 ◽  
Vol 69 (2) ◽  
pp. m86-m86 ◽  
Author(s):  
Cedric W. Holzapfel ◽  
Bernard Omondi
Keyword(s):  
Palladium Complex ◽  
Solvent Molecule ◽  
Membered Ring ◽  
The Other ◽  
Coordination Geometry ◽  
Inversion Center ◽  
Asymmetric Unit ◽  
Coordination Sites ◽  
Square Planar ◽  
Cl Atoms

The asymmetric unit of the title compound, [Pd2Cl2(C20H26P)2]·2CH2Cl2, contains one half-molecule of the palladium complex and a dichloromethane solvent molecule. In the complex, two PdIIatoms are bridged by two Cl atoms, with the other two coordination sites occupied by a C atom of the biphenyl system and a P atom, resulting in a distorted square-planar coordination geometry of the PdIIatom and a cyclometallated four-membered ring. The Pd2Cl2unit is located about an inversion center. The planes of the rings of the biphenyl system make a dihedral angle of 66.36 (11)°.

scholarly journals Crystal structures of four dimeric manganese(II) bromide coordination complexes with various derivatives of pyridine N-oxide

2019 ◽  
Vol 75 (8) ◽  
pp. 1284-1290
Author(s):  
Sheridan Lynch ◽  
Genevieve Lynch ◽  
Will E. Lynch ◽  
Clifford W. Padgett
Keyword(s):  
Hydrogen Bonding ◽  
Solvent Molecule ◽  
Bound Water ◽  
Manganese Atom ◽  
Coordination Complexes ◽  
Water Molecules ◽  
Inversion Center ◽  
Dimeric Complex ◽  
Bromide Ions ◽  
Derivatives Of

Four manganese(II) bromide coordination complexes have been prepared with four pyridine N-oxides, viz. pyridine N-oxide (PNO), 2-methylpyridine N-oxide (2MePNO), 3-methylpyridine N-oxide (3MePNO), and 4-methylpyridine N-oxide (4MePNO). The compounds are bis(μ-pyridine N-oxide)bis[aquadibromido(pyridine N-oxide)manganese(II)], [Mn2Br4(C5H5NO)4(H2O)2] (I), bis(μ-2-methylpyridine N-oxide)bis[diaquadibromidomanganese(II)]–2-methylpyridine N-oxide (1/2), [Mn2Br4(C6H7NO)2(H2O)4]·2C6H7NO (II), bis(μ-3-methylpyridine N-oxide)bis[aquadibromido(3-methylpyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(H2O)2] (III), and bis(μ-4-methylpyridine N-oxide)bis[dibromidomethanol(4-methylpyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(CH3OH)2] (IV). All the compounds have one unique MnII atom and form a dimeric complex that contains two MnII atoms related by a crystallographic inversion center. Pseudo-octahedral six-coordinate manganese(II) centers are found in all four compounds. All four compounds form dimers of Mn atoms bridged by the oxygen atom of the PNO ligand. Compounds I, II and III exhibit a bound water of solvation, whereas compound IV contains a bound methanol molecule of solvation. Compounds I, III and IV exhibit the same arrangement of molecules around each manganese atom, ligated by two bromide ions, oxygen atoms of two PNO ligands and one solvent molecule, whereas in compound II each manganese atom is ligated by two bromide ions, one O atom of a PNO ligand and two water molecules with a second PNO molecule interacting with the complex via hydrogen bonding through the bound water molecules. All of the compounds form extended hydrogen-bonding networks, and compounds I, II, and IV exhibit offset π-stacking between PNO ligands of neighboring dimers.

Molybdenum–molybdenum quadruple bonds supported by 9,10-anthraquinone carboxylate ligands. Molecular, electronic, ground state and unusual photoexcited state properties

2014 ◽  
Vol 5 (7) ◽  
pp. 2657 ◽  
Author(s):  
Samantha E. Brown-Xu ◽  
Malcolm H. Chisholm ◽  
Christopher B. Durr ◽  
Sharlene A. Lewis ◽  
Thomas F. Spilker ◽  
...  
Keyword(s):  
Ground State ◽  
Electronic Ground State ◽  
Molecular Electronic ◽  
Carboxylate Ligands ◽  
Quadruple Bonds ◽  
Electronic Ground ◽  
Photoexcited State

scholarly journals Crystal structures of three substituted 3-aryl-2-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-ones

2016 ◽  
Vol 72 (8) ◽  
pp. 1108-1112 ◽  
Author(s):  
Hemant P. Yennawar ◽  
David J. Coyle ◽  
Duncan J. Noble ◽  
Ziwei Yang ◽  
Lee J. Silverberg
Keyword(s):  
Crystal Structures ◽  
Dihedral Angle ◽  
Solvent Molecule ◽  
Asymmetric Unit ◽  
Aromatic Rings ◽  
Positional Disorder ◽  
Π Interactions ◽  
Plane Parallel ◽  
Substituent Group ◽  
Racemic Mixtures

Three ring-substituted 3-aryl analogs of 2-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-one, namely 3-(4-methoxyphenyl)-2-phenyl-4H-1,3-benzothiazin-4-one, C21H17NO2S, (I), 2-phenyl-3-[4-(trifluoromethyl)phenyl]-2,3-dihydro-4H-1,3-benzothiazin-4-one toluene hemisolvate, C21H14F3NOS·0.5C7H8, (II), and 3-(3-bromophenyl)-2-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-one toluene hemisolvate, C20H14BrNOS·0.5C7H8, (III), were synthesized and their crystal structures determined. The hemisolvates differ in that in (II), the asymmetric unit comprises two molecules of the benzothiazinone compound and a toluene solvent molecule, whereas in (III), the unit comprises one benzothiazinone molecule and a half-occupancy toluene solvent molecule. All crystals are of racemic mixtures of the chiral 2-C atom of the thiazine moiety, which in all structures has a screw-boat puckering, with the puckering amplitude values within the range 0.575–0.603 Å. In all three structures, the benzene plane of the benzothiazine system makes a dihedral angle in the range 78.60 (5) to 98.40 (5)° with the unsubstituted benzene plane and in the range 70.50 (1) to 121.00 (5)° with the substituted benzene plane. The CF3substituent group in one of the molecules of (II) shows positional disorder, with an occupancy ratio of 0.57 (3):0.43 (3). In the crystals of (I) and (II), weak intermolecular C—H...O interactions are present, giving in (I), molecules arranged in a plane parallel to (010), and in (II), chains alonga. In addition, all three structures show weak C—H...π interactions involving various aromatic rings.

scholarly journals Evaluating Unexpectedly Short Non-covalent Distances in X-ray Crystal Structures of Proteins with Electronic Structure Analysis

2019 ◽  
Author(s):  
Helena W. Qi ◽  
Heather Kulik
Keyword(s):  
Amino Acids ◽  
High Resolution ◽  
Crystal Structures ◽  
Close Contact ◽  
Protein Structures ◽  
Protein Crystal ◽  
X Ray ◽  
High Quality Protein ◽  
Van Der Waals Radii ◽  
Close Contacts

<div><div><div><p>We investigate unexpectedly short non-covalent distances (< 85% of the sum of van der Waals radii) in atomically resolved X-ray crystal structures of proteins. We curate over 13,000 high quality protein crystal structures and an ultra-high resolution (1.2 Å or better) subset containing > 1,000 structures. Although our non-covalent distance criterion excludes standard hydrogen bonds known to be essential in protein stability, we observe over 82,000 close contacts in the curated protein structures. Analysis of the frequency of amino acids participating in these interactions demonstrates some expected trends (i.e., enrichment of charged Lys, Arg, Asp, and Glu) but also reveals unexpected enhancement of Tyr in such interactions. Nearly all amino acids are observed to form at least one close contact with all other amino acids, and most interactions are preserved in the much smaller ultra high-resolution subset. We quantum-mechanically characterize the interaction energetics of a subset of > 6,000 close contacts with symmetry adapted perturbation theory to enable decomposition of interactions. We observe the majority of close contacts to be favorable. The shortest favorable non-covalent distances are under 2.2 Å and are very repulsive when characterized with classical force fields. This analysis reveals stabilization by a combination of electrostatic and charge transfer effects between hydrophobic (i.e., Val, Ile, Leu) amino acids and charged Asp or Glu. We also observe a unique hydrogen bonding configuration between Tyr and Asn/Gln involving both residues acting simultaneously as hydrogen bond donors and acceptors. This work confirms the importance of first-principles simulation in explaining unexpected geometries in protein crystal structures.</p></div></div></div>

Two terphenyl-based diol hosts and corresponding solvent inclusions with dimethylformamide and acetonitrile

2015 ◽  
Vol 71 (9) ◽  
pp. 768-775
Author(s):  
Hendrik Klien ◽  
Wilhelm Seichter ◽  
Konstantinos Skobridis ◽  
Edwin Weber
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Solvent Molecule ◽  
Intramolecular Hydrogen Bonding ◽  
Host Lattice ◽  
Solvent Free ◽  
Guest Molecules ◽  
Solvent Molecules ◽  
Intramolecular Hydrogen ◽  
Supramolecular Aggregates

Having reference to an elongated structural modification of 2,2′-bis(hydroxydiphenylmethyl)biphenyl, (I), the two 1,1′:4′,1′′-terphenyl-based diol hosts 2,2′′-bis(hydroxydiphenylmethyl)-1,1′:4′,1′′-terphenyl, C44H34O2, (II), and 2,2′′-bis[hydroxybis(4-methylphenyl)methyl]-1,1′:4′,1′′-terphenyl, C48H42O2, (III), have been synthesized and studied with regard to their crystal structures involving different inclusions,i.e.(II) with dimethylformamide (DMF), C44H34O2·C2H6NO, denoted (IIa), (III) with DMF, C48H42O2·C2H6NO, denoted (IIIa), and (III) with acetonitrile, C48H42O2·CH3CN, denoted (IIIb). In the solvent-free crystals of (II) and (III), the hydroxy H atoms are involved in intramolecular O—H...π hydrogen bonding, with the central arene ring of the terphenyl unit acting as an acceptor. The corresponding crystal structures are stabilized by intermolecular C—H...π contacts. Due to the distinctive acceptor character of the included DMF solvent species in the crystal structures of (IIa) and (IIIa), the guest molecule is coordinated to the hostviaO—H...O=C hydrogen bonding. In both crystal structures, infinite strands composed of alternating host and guest molecules represent the basic supramolecular aggregates. Within a given strand, the O atom of the solvent molecule acts as a bifurcated acceptor. Similar to the solvent-free cases, the hydroxy H atoms in inclusion structure (IIIb) are involved in intramolecular hydrogen bonding, and there is thus a lack of host–guest interaction. As a result, the solvent molecules are accommodated as C—H...N hydrogen-bonded inversion-symmetric dimers in the channel-like voids of the host lattice.

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