Preferred Label : hypercoordination;
IUPAC definition : A property of main-group atoms in molecular entities to acquire coordination numbers
greater than four (which would comply with the Lewis octet rule). Hypercoordination
may be associated with hypervalency, but usually is referred to peculiar atomic centres
in the electron-deficient species with multicentre σ-bonding, in which the bonding
power of a pair of electrons is spread over more than two atoms. An example of a hypercoordinated
atom is the five-coordinate carbon atom in the methanium cation, where three C–H bonds
may be regarded as normal two center - two electron bonds and the bonding in the remaining
CH sub 2 /sub fragment is governed by the three-centre, two-electron bond. A particular
case of a hypercoordinated atom is the hydrogen atom included into a hydrogen bond.;
Origin ID : HT07051;
See also
A property of main-group atoms in molecular entities to acquire coordination numbers
greater than four (which would comply with the Lewis octet rule). Hypercoordination
may be associated with hypervalency, but usually is referred to peculiar atomic centres
in the electron-deficient species with multicentre σ-bonding, in which the bonding
power of a pair of electrons is spread over more than two atoms. An example of a hypercoordinated
atom is the five-coordinate carbon atom in the methanium cation, where three C–H bonds
may be regarded as normal two center - two electron bonds and the bonding in the remaining
CH sub 2 /sub fragment is governed by the three-centre, two-electron bond. A particular
case of a hypercoordinated atom is the hydrogen atom included into a hydrogen bond.
