title: Solid state and dynamic solution structures of O-carbamidine amidoximes
metadata.name: dc.contributor.author
metadata.value: Kulish, KI
metadata.lang: -
metadata.name: dc.contributor.author
metadata.value: Novikov, AS
metadata.lang: -
metadata.name: dc.contributor.author
metadata.value: Tolstoy, PM
metadata.lang: -
metadata.name: dc.contributor.author
metadata.value: Bolotin, DS
metadata.lang: -
metadata.name: dc.contributor.author
metadata.value: Bokach, NA
metadata.lang: -
metadata.name: dc.contributor.author
metadata.value: Zolotarev, AA
metadata.lang: -
metadata.name: dc.contributor.author
metadata.value: Kukushkin, VY
metadata.lang: -
metadata.name: dc.date.accessioned
metadata.value: 2016-04-07T16:33:15Z
metadata.lang: -
metadata.name: dc.date.available
metadata.value: 2016-04-07T16:33:15Z
metadata.lang: -
metadata.name: dc.date.issued
metadata.value: 2016
metadata.lang: -
metadata.name: dc.identifier.citation
metadata.value: Journal of Molecular Structure 1111 (2016) 142-150
metadata.lang: en_GB
metadata.name: dc.identifier.uri
metadata.value: http://hdl.handle.net/11701/1933
metadata.lang: -
metadata.name: dc.description.abstract
metadata.value: Three new iminium salts [H2N]C(R)ON]C(R0)NH2](p-TolSO3)$½H2O ([1e3](p-TolSO3)$½H2O; R/
  R0 ¼ NMe2/PhCH2 1, NMe2/p-BrC6H4 2, N(CH2)5/p-BrC6H4 3) were synthesized via ZnII-mediated
  amidoxime-cyanamide coupling and their solid structures were studied by X-ray diffraction. Solution
  structure and conformational changes of [1e3](p-TolSO3)$½H2O were studied by dynamic NMR. The
  obtained quantitative data were supported by DFT calculations. All the obtained results help to understand
  the relative stability of the salts [H2N]C(R)ON]C(R0)NH2](X) (R ¼ NAlk2, Alk, Ar) and give a
  further insight into the mechanism of ZnII-mediated generation of 1,2,4-oxadiazoles. The electron
  delocalization and sesquialteral bonds in the [H2N]C(NR2)ON]C(R0)NH2]þ system was recognized by
  estimation of values of activation energy barriers (14e18 kcal/mol by DNMR and 16e17 kcal/mol by DFT
  calculations) for the rotation around the CN bonds for the NR2 groups and inspection of the solid-state Xray
  data along with the Wiberg bond indices (intermediate single/double bond order for the CN distances).
  This electron delocalization is responsible for the stabilization of the positively charged iminium
  cation. The moderate strength hydrogen bonding between the oxime N atom and the ¼NH2 group, which
  is verified from the X-ray, DNMR experiments, and by using quantum chemical calculations, stabilizes the
  iminium salt, but it is still weak to prevent the heterocyclization. Theoretical calculations of the heterocyclization
  of [H2N]C(R)ON]C(R0)NH2]þ to 1,2,4-oxadiazoles demonstrated that it is kinetically hindered
  to a greater extent for R ¼ NAlk2 and this explains their lower reactivity as compared to the
  iminium salts with R ¼ Alk, Ar.
metadata.lang: en_GB
metadata.name: dc.title
metadata.value: Solid state and dynamic solution structures of O-carbamidine amidoximes
metadata.lang: en_GB
resources.filename: file.txt
resources.url: https://dspace.spbu.ru/bitstream/11701/1933/1/file.txt
resources.format: Text
resources.size: 4 B