“…Similar deviations are a distinctive feature of ChBs compared to HaBs and TtBs. Similar ChBs are observed in crystals of conveniently substituted 1,3-diselenetane − and 1,3-ditelluretane , (Figure ), steric hindrance around the chalcogen resulting in longer interactions.…”
Section: Sulfides Disulfides and Selenium And Tellurium
Analoguessupporting
Conspectus
The distribution
of the electron density around
covalently bonded atoms is anisotropic, and this determines the presence,
on atoms surface, of areas of higher and lower electron density where
the electrostatic potential is frequently negative and positive, respectively.
The ability of positive areas on atoms to form attractive interactions
with electron rich sites became recently the subject of a flurry of
papers. The halogen bond (HaB), the attractive interaction
formed by halogens with nucleophiles, emerged as a quite common and
dependable tool for controlling phenomena as diverse as the binding
of small molecules to proteinaceous targets or the organization of
molecular functional materials. The mindset developed in relation
to the halogen bond prompted the interest in the tendency of elements
of groups 13–16 of the periodic table to form analogous attractive
interactions with nucleophiles.
This Account addresses the chalcogen bond (ChB), the attractive interaction formed
by group 16 elements with nucleophiles, by adopting a crystallographic
point of view. Structures of organic derivatives are considered where
chalcogen atoms form close contacts with nucleophiles in the geometry
typical for chalcogen bonds. It is shown how sulfur, selenium, and
tellurium can all form chalcogen bonds, the tendency to give rise
to close contacts with nucleophiles increasing with the polarizability
of the element. Also oxygen, when conveniently substituted, can form
ChBs in crystalline solids. Chalcogen bonds can be strong enough to
allow for the interaction to function as an effective and robust tool
in crystal engineering. It is presented how chalcogen containing heteroaromatics,
sulfides, disulfides, and selenium and tellurium analogues as well
as some other molecular moieties can afford dependable chalcogen bond
based supramolecular synthons. Particular attention is given to chalcogen
containing azoles and their derivatives due to the relevance of these
moieties in biosystems and molecular materials. It is shown how the
interaction pattern around electrophilic chalcogen atoms frequently
recalls the pattern around analogous halogen, pnictogen, and tetrel
derivatives. For instance, directionalities of chalcogen bonds around
sulfur and selenium in some thiazolium and selenazolium derivatives
are similar to directionalities of halogen bonds around bromine and
iodine in bromonium and iodonium compounds. This gives experimental
evidence that similarities in the anisotropic distribution of the
electron density in covalently bonded atoms translates in similarities
in their recognition and self-assembly behavior. For instance, the
analogies in interaction patterns of carbonitrile substituted elements
of groups 17, 16, 15, and 14 will be presented. While the extensive
experimental and theoretical data available in the literature prove
that HaB and ChB form twin supramolecular synthons in the solid, more
experimental information has to become available before such a statement
can be safely extended to interactions wherein ele...
“…Similar deviations are a distinctive feature of ChBs compared to HaBs and TtBs. Similar ChBs are observed in crystals of conveniently substituted 1,3-diselenetane − and 1,3-ditelluretane , (Figure ), steric hindrance around the chalcogen resulting in longer interactions.…”
Section: Sulfides Disulfides and Selenium And Tellurium
Analoguessupporting
Conspectus
The distribution
of the electron density around
covalently bonded atoms is anisotropic, and this determines the presence,
on atoms surface, of areas of higher and lower electron density where
the electrostatic potential is frequently negative and positive, respectively.
The ability of positive areas on atoms to form attractive interactions
with electron rich sites became recently the subject of a flurry of
papers. The halogen bond (HaB), the attractive interaction
formed by halogens with nucleophiles, emerged as a quite common and
dependable tool for controlling phenomena as diverse as the binding
of small molecules to proteinaceous targets or the organization of
molecular functional materials. The mindset developed in relation
to the halogen bond prompted the interest in the tendency of elements
of groups 13–16 of the periodic table to form analogous attractive
interactions with nucleophiles.
This Account addresses the chalcogen bond (ChB), the attractive interaction formed
by group 16 elements with nucleophiles, by adopting a crystallographic
point of view. Structures of organic derivatives are considered where
chalcogen atoms form close contacts with nucleophiles in the geometry
typical for chalcogen bonds. It is shown how sulfur, selenium, and
tellurium can all form chalcogen bonds, the tendency to give rise
to close contacts with nucleophiles increasing with the polarizability
of the element. Also oxygen, when conveniently substituted, can form
ChBs in crystalline solids. Chalcogen bonds can be strong enough to
allow for the interaction to function as an effective and robust tool
in crystal engineering. It is presented how chalcogen containing heteroaromatics,
sulfides, disulfides, and selenium and tellurium analogues as well
as some other molecular moieties can afford dependable chalcogen bond
based supramolecular synthons. Particular attention is given to chalcogen
containing azoles and their derivatives due to the relevance of these
moieties in biosystems and molecular materials. It is shown how the
interaction pattern around electrophilic chalcogen atoms frequently
recalls the pattern around analogous halogen, pnictogen, and tetrel
derivatives. For instance, directionalities of chalcogen bonds around
sulfur and selenium in some thiazolium and selenazolium derivatives
are similar to directionalities of halogen bonds around bromine and
iodine in bromonium and iodonium compounds. This gives experimental
evidence that similarities in the anisotropic distribution of the
electron density in covalently bonded atoms translates in similarities
in their recognition and self-assembly behavior. For instance, the
analogies in interaction patterns of carbonitrile substituted elements
of groups 17, 16, 15, and 14 will be presented. While the extensive
experimental and theoretical data available in the literature prove
that HaB and ChB form twin supramolecular synthons in the solid, more
experimental information has to become available before such a statement
can be safely extended to interactions wherein ele...
“…In 131 [184] , the association leading to a linear chain involves both selenium atoms connecting to the carbonyl-oxygen atom of a translationally related molecule, Fig. 13 c. A double-chain is noted for 132 [185] , Fig. 13 d. Here, two selenium atoms occur diagonally opposite positions in a centrosymmetric C 2 Se 2 square, and each forms a Se … O(carbonyl) interaction to form a linear chain.…”
Section: One-dimensional Assembles Mediated By Se
…
mentioning
Highlights
Selenium
…
oxygen chalcogen bonding is important in relevant crystal structures.
Se
…
O interactions, operating alone, are found in 13% of possible structures.
Se
…
O(carbonyl) interactions occur in 50% of possible structures.
Zero-, one-, two- and three-dimensional architectures are sustained by Se
…
O interactions.
One-dimensional chains are found in 55% of examples.
Eine Losung von je 1.0 mmol4 und 5 in 10 mL wasserfreiem MeOH wird unter den in Tabelle 1 angegebenen Bedingungen in einem abgeschmolzenen Polytetrafluorethylen(PTFE)-Schrumpfschlauch komprimiert [lo]. Die Losung wird eingedampft und der Ruckstand in 10 mL Wasser aufgenommen. Nach Ausschutteln mil Ethylacetat wird die waDrige Phase mit verdiinnter Salzsaure vorsichtig (Boc-Rest saurelabil!) auf pH = 1 angesauert und das Produkt 6 mit Ethylacerat extrahiert. Aus dem organischen Extrakt IaDt sich nach Trocknen iiber Na,SO, 6 durch Eindampfen undioder Zugabe von Petrolether in reiner Form isolieren. Die in Tabelle I angegebenen Reaktionszeiten und Ausbeuten sind nicht optimiert.
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