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The main engineering strategies currently in use are hydrogen-and halogen bonding and coordination bonding. [2] These may be understood with key concepts such as the supramolecular synthon and the secondary building unit. [3] An example of crystal engineering using hydrogen bonding reported by Wuest and coworkers in J. Am. Chem. Soc., 2007 ...
The synthesis of (E)-4-iodo-3-methylbut-3-en-1-ol [12] shown below is a typical application of this reaction: For terminal alkynes, the reaction generally proceeds with good regioselectivity (>90:10 rr) and complete syn selectivity, even in the presence of propargylic or homopropargylic heteroatom substituents.
The initial studies revealed the typical radii of atoms, and confirmed many theoretical models of chemical bonding, such as the tetrahedral bonding of carbon in the diamond structure, [30] the octahedral bonding of metals observed in ammonium hexachloroplatinate (IV), [47] and the resonance observed in the planar carbonate group [33] and in ...
The greater stabilization that results from metal-to-ligand bonding is caused by the donation of negative charge away from the metal ion, towards the ligands. This allows the metal to accept the σ bonds more easily. The combination of ligand-to-metal σ-bonding and metal-to-ligand π-bonding is a synergic effect, as each enhances the other.
Gray tin has no metallic properties at all, is a dull gray powdery material, and has few uses, other than a few specialized semiconductor applications. [24] Although the α–β transformation temperature of tin is nominally 13.2 °C, impurities (e.g. Al, Zn, etc.) lower the transition temperature well below 0 °C, and upon addition of Sb or Bi ...
A valence bond structure resembles a Lewis structure, but when a molecule cannot be fully represented by a single Lewis structure, multiple valence bond structures are used. Each of these VB structures represents a specific Lewis structure. This combination of valence bond structures is the main point of resonance theory.
What is in most respects a purely covalent structure can support metallic delocalization of electrons; metallic carbon nanotubes are one example. Transition metals and intermetallic compounds based on transition metals can exhibit mixed metallic and covalent bonding, [ 6 ] resulting in high shear strength, low ductility, and elevated melting ...
Crystal structure of sodium chloride (NaCl) with sodium cations (Na +) in purple and chloride anions (Cl −) in green. The yellow stipples represent the electrostatic force between the ions of opposite charge. Ionic bonding is a type of electrostatic interaction between atoms that have a large electronegativity difference.