Conformational analysis of coordination compounds. XI. Molecular structure of tetraammine{(±)-pentane-2,4-diamine)cobalt(III) dithionate

1981 ◽  
Vol 34 (1) ◽  
pp. 45 ◽  
Author(s):  
TW Hambley ◽  
CJ Hawkins ◽  
JA Palmer ◽  
MR Snow
Keyword(s):  
Conformational Analysis ◽  
Chelate Ring ◽  
Minimum Energy ◽  
Chair Conformation ◽  
Energy Difference ◽  
Boat Conformation ◽  
Anisotropic Temperature ◽  
Strain Energy Minimization ◽  
Temperature Factors ◽  
Good Agreement

The crystal structure of tetraammine{(�)-pentane-2,4-diamine}cobalt(III) dithionate dihydrate [Co{(�)-ptn}(NH3)4] (S2O6)1.5,2H2O has been determined by X-ray structure analysis. The crystals are triclinic with the space group Pī, with a 11.43, b 11.65, c 7.78 �, α 100.48�, β 105.95�, and γ 75.95�. The structure has been refined by least-squares methods with anisotropic temperature factors to an R value of 0.043 for 2654 reflections. The six-membered diamine chelate ring has a skew-boat conformation in which the two methyl groups are in equatorial orientations. A strain- energy-minimization calculation for the complex reveals an energy difference of 8.3 kJ mol-l between the preferred skew-boat conformation and the chair conformation. The calculated minimum-energy geometry for the skew-boat conformation is in good agreement with the observed structure for the chelate ring in the dithionate salt. The lH N.M.R. spectra of this complex and other complexes of the chiral isomer of pentane-2,4-diamine are discussed in terms of the observed structures and the conformational analysis.

Conformational analysis of coordination compounds. XIII. Complexes of 2-methylpentane-2,4-diamine

1981 ◽  
Vol 34 (12) ◽  
pp. 2525 ◽  
Author(s):  
TW Hambley ◽  
CJ Hawkins ◽  
JA Palmer ◽  
MR Snow
Keyword(s):  
Chelate Ring ◽  
Cobalt Complex ◽  
Platinum Complex ◽  
Chair Conformation ◽  
Geometrical Parameters ◽  
Boat Conformation ◽  
Space Group ◽  
X Ray ◽  
Strain Energy Minimization ◽  
Good Agreement

The crystal structures of tetraammine{(�)-2-methylpentane-2,4-diamine} cobalt(III) tetrachlorozincate chloride and 2,2'-bipyridine{(�)-2-methylpentane-2,4-diamine)platinum(II) nitrate semihydrate have been determined by X-ray structure analysis. The former crystals are orthorhombic with the space group P212121, with a 12.49, b 20.16 and c 7.68 �. The latter crystals are also orthorhombic but with the space group Pbca with a 14.96, b 28.69 and c 19.45 �. Both structures have been refined by least-squares methods to weighted R values of 0.034 (1407 reflections) and 0.055 (2301 reflections), respectively. The six-membered diamine chelate ring has a flattened chair conformation in the cobalt complex, and an unsymmetric boat conformation in the platinum complex. Strain-energy-minimization calculations show these structures correspond to energy minima and the calculated geometrical parameters are in good agreement with those observed for the chelate ring. Proton n.m.r. spectra are consistent with the chair conformation being almost exclusively populated in the ammine complex and in the tetracyanocobaltate(III) complex in aqueous solution, but the and 13C n.m.r. spectra of the platinum(II) complex show that, although the chair conformer predominates, the boat conformation is significantly populated in solution.

Conformational analysis of coordination compounds. XIV. Proton, carbon-13, cobalt-59 and platinum-195 n.m.r. spectra of six-membered diamine chelaterings

1982 ◽  
Vol 35 (9) ◽  
pp. 1815 ◽  
Author(s):  
CJ Hawkins ◽  
RH Holm ◽  
JA Palmer ◽  
DD Traficante
Keyword(s):  
Conformational Analysis ◽  
Mole Fraction ◽  
Coordination Compounds ◽  
Chelate Ring ◽  
Chair Conformation ◽  
Boat Conformation ◽  
Methyl Group ◽  
Chelate Rings

The conformations adopted by six-membered diamine chelate rings in complexes of the types [Co(NH3),L]3+, [Co(CN)4L]-, [Pt(bpy)L]2+, [Pt(NH3)2L]2+ and [CoL3]3+ have been studied by n.m.r. techniques. The ligands (L) used in the study were meso- and (+)-pentane-2,4-diamine, butane-1,3-diamine, propane-1,3-diamine and 2-methylpentane-2,4-diamine. It has been found that for most complexes of meso-pentane-2,4-diamineth e diequatorial chair conformation predominates, although for the bipyridineplatinum(II) complex it is unclear whether the skew-boat conformation is significantly populated or the chair structure is unusually distorted. For (+)-pentane-2,4-diamine chelates, which normally adopt the skew-boat conformation in octahedral complexes, the chair conformation with an axial and an equatorial methyl group has a mole fraction of 0.5 and 0.7 for the bipyridine- and diammine-platinum(II) complexes, respectively. In tetraammine(butane-1,3- diamine)cobalt(III) the chelate ring is in the chair conformation with the methyl equatorial.

The Dichloroplatinum(II) and Dichloropalladium(II) Complexes of 1,4-Diazacycloheptane: Preparative, Structural and Conformational Studies

1996 ◽  
Vol 49 (12) ◽  
pp. 1301 ◽  
Author(s):  
GW Allen ◽  
ECH Ling ◽  
LV Krippner ◽  
TW Hambley
Keyword(s):  
Crystal Structures ◽  
Chelate Ring ◽  
Chair Conformation ◽  
Monoclinic Space Group ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Membered Chelate Ring ◽  
Alternative Conformation

The preparation and purification of [Pt( hpip )Cl2] and [Pd( hpip )Cl2] ( hpip = homopiperazine = 1,4-diazacycloheptane) are described. Crystal structures of [Pt( hpip )Cl2] and [Pd( hpip )Cl2] have been determined by X-ray diffraction methods and refined to R values of 0.023 (932 F) and 0.023 (948 F). The crystals of [Pt( hpip )Cl2] are orthorhombic, space group Pbcm , a 7.7019(8), b 9.8080(12), c 12.1944(14) Ǻ, and those of [Pd( hpip )Cl2] are monoclinic, space group P21/m, a 6.1001(9), b 11.527(2), c 6.458(I) Ǻ, β 106.30(2)°. The seven- membered rings of the ligands in both complexes adopt boat-like conformations in which the five- membered chelate ring has an eclipsed N-C-C-N group and the six- membered chelate ring adopts a chair conformation. Molecular mechanics methods were used to investigate whether this conformation was a crystallographic artefact but it was found to be real. An alternative conformation in which the six-membered chelate ring adopts a skew-boat conformation was also investigated. It was found to be less stable than the conformation observed in the crystal structures, but to a degree that depends on whether non-bonded interactions involving the metal atom were included or not.

Crystal and Molecular Structure of the s-fac-[Co((S)-Asp)(medien)]ClO4 . H2O . HClO4 Isomer

1993 ◽  
Vol 58 (2) ◽  
pp. 335-342 ◽  
Author(s):  
Jan Ondráček ◽  
Jaroslav Maixner ◽  
Jana Ondráčková ◽  
František Jursík
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Chelate Ring ◽  
Complex Cation ◽  
Heavy Atom ◽  
Boat Conformation ◽  
Membered Chelate Ring ◽  
Anisotropic Temperature ◽  
Hydroxonium Cation ◽  
Heavy Atom Method

The crystal and molecular structure of s-fac-[Co((S)-Asp)(medien)]ClO4 . H2O . HClO4 was elucidated by the heavy atom method. The positional parameters of the nonhydrogen atoms and their anisotropic temperature parameters were refined based on 2 474 observed reflection with final values of R = 0.0603 and wR = 0.0616. The substance crystallized in the orthorhombic system in the space group P212121, Z = 4, a = 8.536(1), b = 13.378(1), c = 16.899(2) Å. The structure comprises layers of the complex cation which alternate with layers containing two perchlorate anions and one hydroxonium cation. The five-membered chelate ring of 4-methyl-1,4,7-triazaheptane exist in the asymmetric λ, δ envelope conformations and the N-CH3 group of the triamine has the exo orientation. The five-membered ring of (S)-aspartic acid assumes the symmetric envelope conformation, the six-membered chelate ring, the skew boat conformation.

The crystal and molecular structure of cobalt(III) sym-fac-N-(2-aminoethyl)-1,3-diaminopropane-(S)-aspartate perchlorate, sym-fac-[Co-(aepn)(S)-Asp]ClO4

1987 ◽  
Vol 52 (4) ◽  
pp. 949-956 ◽  
Author(s):  
Bohumil Kratochvíl ◽  
Jan Ondráček ◽  
Jana Ondráčková ◽  
Jiřina Soldánová ◽  
František Jursík ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Structural Parameters ◽  
Heavy Atom ◽  
Chair Conformation ◽  
Elementary Cell ◽  
Membered Ring ◽  
Reliability Factor ◽  
Anisotropic Temperature ◽  
Temperature Factors

The crystal and molecular structure of sym-fac-[Co-(aepn) (S)-Asp]ClO4 was solved by the heavy atom method. The positions of the nonhydrogen atoms and their anisotropic temperature factors were refined. On the basis of 1 514 observed reflection intensities, a final reliability factor value of R = 0.096 was obtained (wR = 0.101). The substance crystallizes in the orthorhombic system in the P212121 space group. The elementary cell contains four formula units and has dimensions of a = 704.0(6), b = 939.4(7), c = 2 369(2) pm. The secondary nitrogen atom of the triamine has S confuguration. The five-membered ring has the λ conformation and the six-membered ring the flattened chair conformation. Selected structural parameters indicate that facial coordination of N-2-aminoethyl-1,3-diaminopropane leads to decreased strain in the coordinated, slightly deformed octahedron than meridional coordination and also that the chelate rings of the triamine are conformationally dependent. The bond lengths and angles of the part formed by (S)-aspartic acid agree with the corresponding values in [Co-((S)-Asp)2]-.

Single-Crystal Neutron Diffraction Analysis of Anion–Cation Interactions in Perdeuteroacetylcholine Bromide at 100 K

1997 ◽  
Vol 53 (1) ◽  
pp. 176-180 ◽  
Author(s):  
N. Shankland ◽  
A. J. Florence ◽  
C. C. Wilson
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Close Contact ◽  
Intermolecular Forces ◽  
Hydrogen Bond Interactions ◽  
Anisotropic Temperature ◽  
Pyramidal Configuration ◽  
Pulsed Neutron ◽  
Temperature Factors ◽  
Good Agreement

The interaction of the neurotransmitter acetylcholine with receptor binding sites has been well studied over the years, but much is still unknown about how intermolecular forces govern the lock-and-key fit. Here we present an analysis of cation–anion hydrogen-bond interactions in a single-crystal of perdeuteroacetylcholine bromide, using pulsed neutron diffraction data to refine the X-ray crystal structure. The molecule crystallizes in space group P21/n, with a = 10.951 (4), b = 13.396 (8), c = 7.072(4) Å, β = 108.88(3)°, Z = 4. The final refinement included anisotropic temperature factors on all atoms and converged to wR(F) = 0.055 (244 parameters). The pyramidal configuration of C--D...Br− contacts observed in the crystal is in good agreement with ab initio molecular orbital predictions of favoured configuration and is consistent with a modest polarization of C--D bonds close to the N atom. There is evidence that close contact with Br− is hindered by the repulsive influence of the ester O atoms, dependent on the conformation of the acetylcholine cation. This is the most detailed picture to date of close interatomic contacts around the cation and analogies are drawn with the bonding of acetylcholine to its receptors.

Structural Studies of Seven Compounds of Cobalt(III) With trans-6,13-Diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane

1992 ◽  
Vol 45 (10) ◽  
pp. 1663 ◽  
Author(s):  
NF Curtis ◽  
WT Robinson ◽  
DC Weatherburn
Keyword(s):  
Chelate Ring ◽  
Chair Conformation ◽  
Boat Conformation ◽  
Structural Studies ◽  
Molecular Plane ◽  
X Ray ◽  
Membered Chelate Ring ◽  
Additional Ligand ◽  
Primary Amino ◽  
Amine Groups

The structures of seven compounds of trans-6,13-diamino-6,13-dimethyl-1,4,8,11-tetraacyclotetradecane (diam) with cobalt(III) have been determined by X-ray diffractometry: (1), trans-α-[{Co(diam-N5)}2(O2)](ClO4)4.2H2O (monoclinic, P21/n, a 10.673(2), b 22.924(8), c 19.332(5) Ǻ,β 114 19(2)°, R 0.044 for 4547reflections); (2), trans-α-[Co(diam-N5)Cl](ClO4)2 (orthorhombic, P 212121, a 9.043(4), b 11.214(4), c 21.431(8) A, R 0.055 for 1541 reflections); (3), trans-α- Co(diamH-N5)Cl] [ZnCl4] Cl.H2O (orthorhombic, Pna 21, a 25.26(5), b 9.866(2), c 9.457(2) 1, R 0.108 for 1686 reflections); (4), trans-α-[Co(diamH-N5)(H2O)Cl3.ClO4 (monoclinic, P 21/n, a 12.928(8), b 8.554(5), c 20.624(12) A, β 106.00(4)°, R 0.060 for 2094 reflections); (5), trans-γ-[Co(diamH-N5)Cl]Cl3.3H2O (orthorhombic, P212121, a 12.895(7), b 12.898(9), c 13 -417(4) Ǻ, R 0.062 for 860 reflections); (6), trans-β-[Co(diamHN5) Cl] [ZnCl4]CI.½H2O.½C3.H7OH(triclinic, P1, a 10.469(4), b 9.167(5), c 15.464(6) Ǻ, α 73.74(4), β 71.15(3), γ 73.70(1)°, R 0.045 for 3685 reflections); (7), trans-β-[Co(diamH2- N4)Cl2] [ZnCl4]Cl.½H2O.½C2.H5OH(triclinic, P1, a 10.138(2), b 12.011(3), c 12-451(2) Ǻ, α 79,87(2), β 66.64(1), γ 66.64(1)°, R 0.035 for 2637 reflections). The cations of compounds (1)-(6) all have pentadentate diam (diam-N5 or diamH-N5) with one primary amino substituent coordinated trans to the additional ligand. Compounds (1)-(4) have the pentadentate macrocycle in cyclam configuration (1). R,S,R,S, with all four secondary amine groups on the same side of the molecular plane, with one six-membered chelate ring in a boat conformation with the amino substituent coordinated, and the other in a chair conformation. Compound (5) has the pentadentate macrocycle in configuration (2), R,R,S,R, with one NH group alone on one side of the molecular plane with the six-membered chelate ring with the non-coordinated amrnonio substituent in a skew conformation. Compounds (6) and (7) have the R,R,S,S configuration (S'), (6) having diamH-N5 with one amine substituent coordinated, and (7) with planar tetradentate diamH2-N4 in the macrocycle conformation usual for planar coordinated cyclam compounds, the ammonio substituents being equatorially oriented.

The Crystal and Molecular Structure of sym-fac-(1,4,7-Triazaheptane)-(S)-aspartatocobalt(III) Diperchlorate Dihydrate

1994 ◽  
Vol 59 (5) ◽  
pp. 1052-1058 ◽  
Author(s):  
Jan Ondráček ◽  
Jana Ondráčková ◽  
Jaroslav Maixner ◽  
František Jursík
Keyword(s):  
Molecular Structure ◽  
Aspartic Acid ◽  
Crystal And Molecular Structure ◽  
Heavy Atom ◽  
Membered Ring ◽  
Boat Conformation ◽  
Hydrogen Atoms ◽  
Orthorhombic System ◽  
Anisotropic Temperature ◽  
Heavy Atom Method

The crystal and molecular structure of s-fac-[Co((S)-Asp)(dien)]ClO4 . HClO4 .2 H2O (dien = 1,4,7-triazaheptane) was solved by the heavy atom method. The position parameters of the non-hydrogen atoms and their anisotropic temperature parameters were refined based on 1 726 observed reflections with a final value of R = 0.073. The substance crystallizes in the orthorhombic system in the space group P212121, Z = 4, a = 8.506(1), b = 17.171(2), c = 13.277(1) Å. The structure involves hydrogen bonds between the O2, O4 and HN2 atoms of aspartic acid and the two molecules of water. The five-membered dien chelate rings take the asymmetric envelope conformations. The five-membered ring of (S)-aspartic acid possesses the symmetric envelope conformation whereas the six-membered ring exhibits the skew boat conformation.

Crystal Structure and Conformation of Ring A of 2β-Bromo-19β,28-epoxy-18α-oleanan-3-one

1993 ◽  
Vol 58 (11) ◽  
pp. 2737-2744 ◽  
Author(s):  
Jiří Novotný ◽  
Jaroslav Podlaha ◽  
Jiří Klinot
Keyword(s):  
Crystal Structure ◽  
Opposite Direction ◽  
Chair Conformation ◽  
Boat Conformation ◽  
Form Ring ◽  
Twist Boat

The crystal structure of β-bromo-19β,28-epoxy-18α-oleanan-3-one was elucidated. The crystal is orthorhombic, P212121, a = 9.686(1), b = 14.355(2), c = 19.687(4) Å, Z = 4, R = 0.042 for 2 410 observed reflections. Rings B, C, D and E adopt the chair conformation, the five membered ether cycle in ring E occurs in the envelope form. Ring A takes the twist-boat conformation turned towards the classical boat with C2 and C5 in the stem-stern position, in contrast to the conformation in solution, which is turned in the opposite direction towards the classical boat with C3 and C10 in the stem-stern positions.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

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