Lonepair

Hydrophilic Groups. Water solubiUty can be achieved through hydrophilic units in the backbone of a polymer, such as O and N atoms that supply lonepair electrons for hydrogen bonding to water. SolubiUty in water is also achieved with hydrophilic side groups (eg, OH, NH2, CO2, SO3 ). 

Among the boron halides, B4CI4 is of interest as both B4H4 and B411 do not exist. Figure 13.3.7 shows the molecular structure of B4CI4, which has a tetrahedral B4 core consolidated by four terminal B-Cl 2c-2e bonds and four BBB 3c-2e bonds on four faces. This structure is further stabilized by a-n interactions between the lonepairs of Cl atoms and BBB 3c-2< bonds. The... 

The highest occupied Molecular orbital (HOMO) is the carbon lonepair 3s orbital and the lowest unoccupied molecular orbital (LUMO) is antibonding 2p. 

Table Hybridisation and Structure involving lonepair Hybridi- Bonded Lone Bond Shape Example sation pair pair angle...

In reaction between BF3 and NH3, boron accepts the lonepair from nitrogen forming a covalent bond. 

This can be rationalized by assuming that the breaking of one S—S single bond (ca. 61 kcal/Mol 6)) is nearly compensated for by the electron-rich three center bond. In other words, the linear arrangement of three centers as in /a favours an electron-rich three-center bond. The energy difference between an S—S sulfur atom on one side and an electron-rich three-center bond on the other is small. 

Pyrrole is possibly one of the most reactive heterocycles thanks to its lonepair electrons at the nitrogen atom. The enormous reactivity of pyrrole in electrophilic substitution reactions explains the occurrence of more than 100 naturally occurring halogenated pyrroles. Indeed, the pyrrole ring is widely distributed in nature. It occurs in both terrestrial and marine plants and animals. An illustration of the abundant complex natural pyrroles is konbu acidin A, a sponge metabolite that inhibits cyclin-dependent kinase 4 (CDK4). 

Normal paired lonepair R N — These two electrons may be paired or unpaired... 

A NITROGEN ATOM WITH A NEGATIVE CHARGE WILL HAVE N. LONE PAIR(S) A NITROGEN ATOM WITH NO FORMAL CHARGE WILL HAVE V. N. LONE PAIR(S) A NITROGEN ATOM. , WITH A POSITIVE / CHARGE WILL HAVE LONEPAIR(S) —... 

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