A comparative conformational study of (C6H5O)2P(O)(NHC(S)NHCH2C6H5) and analogous X-ray structures: energy calculations (solid-state/gas phase)

The preparation of the N-(2-hydroxypropyl)-N-alkylhydroxylamines, 6a (R = CH3) and 6b (R = CH2Ph), and their reactions with phenylboronic acid are described. Regardless of the molar ratios of reactants employed, the reaction with 6b leads to the 1:2 condensate 1-benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane, 7, while that with 6a gives rise to the 1:1 condensate 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-diboratatricyclo[5.3.1. 12,6]dodecane, 11 (the cyclic BONBON dimer of 4,6-dimethyl-2-phenyl-1,3-dioxa-4-aza-2-boracyclohexane, 9). Compounds 7 and 11 both crystallize in the triclinic space group [Formula: see text]: for 7; a = 13.126(1), b = 15.337(1), c = 10.9469(5) Å, α = 91.727(5), β = 104.647(5), γ = 72.922(7)°, Z = 4; and for 11; a = 9.0807(4), b = 9.1653(3), c = 6.4876(2) Å, α = 97.708(3), β = 108.830(3), γ = 89.188(4)°, Z = 1. The structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.038 and 0.032 for 5879 and 1827 reflections with I ≥ 3σ(F2), respectively. Compound 7 has the expected bicyclic pyroboronate structure, but represents the first reported N-substituted example of this type of compound. Bond lengths involving boron in 7 are (C) O—B(sp3) = 1.428(2) and 1.420(2), (B)O—B(sp3) = 1.472(2) and 1.468(2), N—B(sp3) = 1.737(2) and 1.762(2), C(phenyl)—B(sp3) = 1.588(2) and 1.584(2), (N)O—B(sp2) = 1.402(2) and 1.404(2), (B)O—B(sp2) = 1.331(2) and 1.329(2), C(phenyl)—B(sp2) = 1.555(3) and 1.553(2) Å. The X-ray analysis establishes a centrosymmetric, twofold N → B coordinated, dimeric structure in the solid state for 11 in which each B—O—N segment of a central six-membered BONBON ring is bridged by an O—C—C moiety. Compound 11 represents the first fully characterized example of a new type of "BONBON" compound. Bond distances involving the boron atom are (N)O—B = 1.465(1), (C)O—B = 1.428(1), N—B = 1.695(2), and C(phenyl)—B = 1.607(2) Å. Spectroscopic evidence indicates that in solution and in the gas phase this material exists predominantly as the monomer 9.

Download Full-text

Cyclic hexapeptoids with N-alkyl side chains: solid-state assembly and thermal behaviour

CrystEngComm ◽

10.1039/d0ce01136c ◽

2020 ◽

Vol 22 (38) ◽

pp. 6371-6384 ◽

Cited By ~ 1

Author(s):

Giovanni Pierri ◽

Rosaria Schettini ◽

Jürgen Nuss ◽

Robert E. Dinnebier ◽

Francesco De Riccardis ◽

...

Keyword(s):

Solid State ◽

Thermal Behaviour ◽

Lattice Energy ◽

Side Chains ◽

X Ray Diffraction ◽

Energy Calculations ◽

X Ray ◽

Alkyl Side Chains

The solid state assembly of two cyclic hexapeptoids decorated respectively with five and six carbon N-alkyl side chains is analyzed by X-ray diffraction, intermolecular energies and lattice energy calculations.

Download Full-text

Configurations and conformations of glycosyl sulfoxides

Canadian Journal of Chemistry ◽

10.1139/v10-091 ◽

2010 ◽

Vol 88 (11) ◽

pp. 1154-1174 ◽

Cited By ~ 6

Author(s):

Hong Liang ◽

Micheline MacKay ◽

T. Bruce Grindley ◽

Katherine N. Robertson ◽

T. Stanley Cameron

Keyword(s):

Solid State ◽

Dft Calculations ◽

Gas Phase ◽

Density Functional ◽

Lone Pair ◽

Azido Group ◽

X Ray Diffraction ◽

X Ray ◽

Comparison Of The Results ◽

P Type

X-ray crystallographic studies of two axial glycosyl sulfoxides having RS configurations (derivatives of phenyl 2-azido-2-deoxy-1-thio-α-d-galactopyranoside S-oxide) show that they adopt anti conformations in the solid state, in contrast to previous observations and assumptions. Density functional theory (DFT) calculations at the B3lYP6–311G+(d,p)/6–31G(d) level confirm that anti conformations of both phenyl and methyl RS glycosyl sulfoxides of 2-azido-2-deoxy-α-d-pyranosides are more stable than exo-anomeric conformations in the gas phase. 1D NOE measurements indicate that the more polar exo-anomeric conformers are only populated to a slight extent in solution. The anti conformations are distorted so that the glycosyl substituents are closer to being eclipsed with H1. This distortion allows S n → σ* overlap if the sulfur lone pair is a p-type lone pair. Evidence for this overlap comes from short C1–S bond distances, as short as the comparable bond distances in the X-ray crystal structure and in the results from DFT calculations for the SS glycoside, which does adopt the expected exo-anomeric conformation, both in the solid state and in solution, and has normal n → σ* overlap. For 2-deoxy derivatives not bearing a 2-azido group, gas-phase DFT calculations at the same level indicate that the anti- and exo-anomeric conformers have comparable stabilities. Comparison of the results of the two series shows that electronegative substituents in equatorial orientations at C2 destabilize conformations with parallel S–O arrangements, the conformation favored by having an endocyclic C–O dipole antiparallel to the S–O dipole, by about 2.5 kcal mol–1 (1 cal = 4.184 J). An equatorial glycosyl sulfoxide, (SS) phenyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-1-thio-β-d-glucopyranoside S-oxide, also adopts an anti conformation in the solid state as shown by X-ray diffraction. It also adopts this conformation in solution, in contrast to studies of other equatorial glycosyl sulfoxides.

Download Full-text

Tris [(trimethylsilyl)oxy] antimony

Zeitschrift für Naturforschung B ◽

10.1515/znb-1994-0701 ◽

1994 ◽

Vol 49 (7) ◽

pp. 855-858 ◽

Cited By ~ 8

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.

Download Full-text

The application of gas phase and solid state X-ray photoelectron spectroscopy to the investigation of derivatives containing the repeating SN unit

Synthetic Metals ◽

10.1016/0379-6779(80)90007-7 ◽

1980 ◽

Vol 1 (2) ◽

pp. 161-173 ◽

Cited By ~ 4

Author(s):

Patrick Brant ◽

David C. Weber ◽

Curtis T. Ewing ◽

Forrest L. Carter ◽

Joseph A. Hashmall

Keyword(s):

Solid State ◽

Gas Phase ◽

Photoelectron Spectroscopy ◽

X Ray

Download Full-text

A Conformational Study of the Semisynthetic Ergot Alkaloid - Terguride

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19932944 ◽

1993 ◽

Vol 58 (12) ◽

pp. 2944-2954 ◽

Cited By ~ 4

Author(s):

Michal Hušák ◽

Bohumil Kratochvíl ◽

Petr Sedmera ◽

Josef Stuchlík ◽

Alexandr Jegorov

Keyword(s):

Solid State ◽

Ergot Alkaloid ◽

Direct Methods ◽

2D Nmr ◽

Free Base ◽

Conformational Study ◽

X Ray Diffraction ◽

Triclinic Space Group ◽

X Ray ◽

Nmr Techniques

Conformational analysis studied by 2D NMR techniques and X-ray diffraction methods are reported for the semisynthetic ergot alkaloid - terguride, in the form of free base and as the protonated species. The structure of terguride hydrogen maleate monohydrate (C20H29N4O)+(C4H3O4)- . H2O (II) was solved by direct methods and refined anisotropically to an Rvalue of 0.068 for 1 991 unique observed reflections. The title compound crystallizes in the triclinic space group P1 with lattice parameters a = 7.061(2), b = 9.205(1), c = 12.223(4) Å, α = 96.36(2), β = 107.15(2), γ = 106.67(1)°. Studies revealed that terguride monohydrate (I) and its protonized form (terguride hydrogen maleate monohydrate) possesses the identical conformations both in solutions and in the solid state - an envelope for C and Chair for D ergoline rings.

Download Full-text

1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.14.273 ◽

2018 ◽

Vol 14 ◽

pp. 2940-2948 ◽

Cited By ~ 1

Author(s):

A S Antonov ◽

A F Pozharskii ◽

P M Tolstoy ◽

A Filarowski ◽

O V Khoroshilova

Keyword(s):

Hydrogen Bond ◽

Solid State ◽

Gas Phase ◽

Methoxy Group ◽

Proton Sponge ◽

Hindered Rotation ◽

Aromatic Substituent ◽

Imino Nitrogen ◽

X Ray ◽

Methoxy Groups

The structure and protonation behaviour of four ortho-arylketimines of 1,8-bis(dimethylamonio)naphthalene with a different number of methoxy groups in an aromatic substituent were investigated in solution by NMR (acetone, DMSO, MeCN), in solid state by X-ray analysis and in the gas phase by DFT calculations. Both mono- and diprotonated species were considered. It has been shown that E-isomers of neutral imines can be stabilised by an intramolecular C=N−H···OMe hydrogen bond with a neighbouring methoxy group. Electron-donating OMe groups dramatically increase the basicity of the imino nitrogen, forcing the latter to abstract a proton from the proton sponge moiety in monoprotonated forms. The participation of the out-inverted and protonated 1-NMe2 group in the Me2N−H···NH=C hydrogen bond is experimentally demonstrated. It was shown that the number and position of OMe groups in the aromatic substituents strongly affects the rate of the internal hindered rotation of the NH2 + fragment in dications.

Download Full-text