(1)
A fascinating discovery was the synthesis of spherical carbon-cage molecules
called fullerences. The discovery of fullerene was awarded the noble prize in
chemistry (1996). Fullerenes were first prepared by evaporation of graphite
using laser.
(2)
Fullerences are sooty material so formed consists of C60 with small
amount of C70 and other fullerences containing an even number of carbon
up to 350
(3)
Fullerences have a smooth structure and unlike diamond and graphite, dissolved
in organic solvent like toluene.
(4) C60 is the most stable fullerene.
It has the shape of a football and called buckminsterfullerene
(5)
C60 consists of fused five and
six membered carbon rings
(6)
Six membered rings surrounded by alternatively by hexagons and pentagons of
carbon.
(7)
Five membered rings are surrounded by five hexagons carbon rings.
(8)
There are 12 five –membered rings
(9)
There are 20 Six –membered rings
(10)
In fullerenes all the carbon sp2 hybridised each carbon formed three sigma bond
and the fourth electron delocalized to formed pi bond .
(11)
All the carbon atoms are equivalent but all C-C bond are not equivalent.
(12) In the structure C-C bonds of two different
bond length occur at the fusion of two six membered rings the bond length is C-C = 135.5 pm and at the fusion of five and six
membered rings C-C bond length is 146.7 pm.
(13)
There are both single and double bonds
(14)
The smallest fullerenes are C20.
(15)
Thermodynamically the most stable allotrope of carbon is considered to be
graphite. This is due standard enthalpy of formation of graphite is taken zero
.while enthalpy of formation of diamond and fullerenes are 1.90 KJ/Mole and
38.1 KJ/Mole respectively.
just awesome explanation,it helped me in neet preparation
ReplyDeleteHey thank you for this explanation of back bonding .It is really helpful ��
ReplyDeleteExcellent writing !! Thank you so much chemzipper!!
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