A note on practical aspects of the application of<i>DIRDIF</i>, a procedure for structure elucidation when a part of the structure is known

Parthasarathi, V.; Beurskens, Paul T.; Slot, H. J. Bruins

doi:10.1107/s0108767383001737

Cited by 57 publications

(31 citation statements)

References 2 publications

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“…The structure was solved by direct methods (SHELXS-86 [19]) which revealed the positions of all non-H-atoms of the fused rings and the phenyl group. The remaining non-H-atoms were located in a subsequent Fourier expansion of the structure with the program DIRDIF [20]. The non-H-atoms were refined anisotropically.…”

Section: Experimental Partmentioning

confidence: 99%

Glycosylidene Carbenes. Part 8. Crystal Structure of a Cyclic, N‐Acetylallosamine‐Derived Alkoxy‐alkyl‐diazirine

Linden

Vasella

Witzig

1992

Helvetica Chimica Acta

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The crystal structure of 2-acetamido-l,5-anhydro-l-azi-3-O-benzyl-4,6-0 -benzylidene-1,2-dideoxy-~-allitol (6) is reported, and the structural parameters of the diazirine moiety are compared with those of other free diazirines for which structural information has been determined or calculated previously. Lengthening of the N=N bond and shortening of the C-N bonds can be observed as the substituents at the C-atom of the diazirine ring become more electronegative and/or stronger z-electron donors. This is consistent with descriptions of the bonding nature of diazirines and similar observations made on substituted cyclopropanes., are precursors of glycosylidene carbenes, such as 3, and may be used for a mild, promoter-free, thermal or photochemical glycosidation, especially of acidic, non-nucleophilic alcohols [4] and for the synthesis of cyclopropanes [3] [5].

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Section: Experimental Partmentioning

confidence: 99%

Glycosylidene Carbenes. Part 8. Crystal Structure of a Cyclic, N‐Acetylallosamine‐Derived Alkoxy‐alkyl‐diazirine

Linden

Vasella

Witzig

1992

Helvetica Chimica Acta

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“…Intensity data were collected at low temperature with a Bruker AXS Smart 1000 CCD diffractometer and corrected for Lorentz, polarization, and absorption effects (semiempirical, SADABS). [53] The structures were solved by the heavy-atom method combined with structure expansion by direct methods applied to difference structure factors (DIRDIF) [54,55] and refined by full-matrix least squares methods based on F 2 with all measured unique reflections. [56] All non-hydrogen atoms were given anisotropic displacement parameters.…”

Section: 4-bismentioning

confidence: 99%

The Mechanism of the (Bispidine)copper(II)‐Catalyzed Aziridination of Styrene: A Combined Experimental and Theoretical Study

Comba

Lang

Laorden

et al. 2008

Chemistry A European J

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Experimental and DFT-based computational results on the aziridination mechanism and the catalytic activity of (bispidine)copper(I) and -copper(II) complexes are reported and discussed (bispidine=tetra- or pentadentate 3,7-diazabicyclo[3.1.1]nonane derivative with two or three aromatic N donors in addition to the two tertiary amines). There is a correlation between the redox potential of the copper(II/I) couple and the activity of the catalyst. The most active catalyst studied, which has the most positive redox potential among all (bispidine)copper(II) complexes, performs 180 turnovers in 30 min. A detailed hybrid density functional theory (DFT) study provides insight into the structure, spin state, and stability of reactive intermediates and transition states, the oxidation state of the copper center, and the denticity of the nitrene source. Among the possible pathways for the formation of the aziridine product, the stepwise formation of the two N-C bonds is shown to be preferred, which also follows from experimental results. Although the triplet state of the catalytically active copper nitrene is lowest in energy, the two possible spin states of the radical intermediate are practically degenerate, and there is a spin crossover at this stage because the triplet energy barrier to the singlet product is exceedingly high.

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“…A numerical absorption correction [18] was applied. The structures were solved by direct methods SIR92 [19] and expanded by DIRDIF [20]. Full matrix least-squares refinement was employed.…”

Section: X-ray Structure Determinationmentioning

confidence: 99%

2D sheet frameworks constructed from a diruthenium paddlewheel complex and hexamolybdenum halide clusters

Sugiura

Ota

Ebihara

et al. 2005

Comptes Rendus. Chimie

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A note on practical aspects of the application ofDIRDIF, a procedure for structure elucidation when a part of the structure is known

Cited by 57 publications

References 2 publications

Glycosylidene Carbenes. Part 8. Crystal Structure of a Cyclic, N‐Acetylallosamine‐Derived Alkoxy‐alkyl‐diazirine

Glycosylidene Carbenes. Part 8. Crystal Structure of a Cyclic, N‐Acetylallosamine‐Derived Alkoxy‐alkyl‐diazirine

The Mechanism of the (Bispidine)copper(II)‐Catalyzed Aziridination of Styrene: A Combined Experimental and Theoretical Study

2D sheet frameworks constructed from a diruthenium paddlewheel complex and hexamolybdenum halide clusters

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