Question

Carbene in the singlet state has one lone pair of electrons. Which of the following statements among the dihalocarbenes in the single state is correct?
A. $C{F_2}$ is the most stable singlet carbine which is an amphiphile
B. $CB{r_2}$ is the most stable singlet carbine which is an amphiphile
C. $C{F_2}$ is the most stable singlet carbine which is an electroplate
D. $CB{r_2}$ is the most stable singlet carbine which is an electroplate

Answer 1

Hint: As we know that Carbene is a molecule that contains a neutral carbon atom with a valence of two along with two unshared pair of valence electrons. And singlet state is basically the electronic state of a molecule where all electrons are spin paired and hence only one orientation possible in space.

Complete answer:
As we already know that Carbene is a molecule that contains a neutral carbon atom with a valence of two along with two unshared pairs of valence electrons and they are generated from diazoalkanes through catalytic, thermal or transition metal catalysed processes.
And the singlet state is basically the electronic state of a molecule where all electrons are spin paired and hence only one orientation possible in space.
Now we are given with dihalocarbene we also know that halogen and carbine both are electron deficient species and therefore they will act as electrophile and attract the electrons from each other to form a stable compound. So in $C{F_2}$, the fluorine atoms will share its two electrons each with the carbene atoms having four lone electrons. Therefore the compound will be more stable in singlet state which is an electroplate meaning it can be used as an electrophile in coating.

Hence the correct answer is (C).

Note:
In general, the triplet state is more stable for most of the carbenes but in the case of difluorocarbene, the singlet state is more stable than the triplet state because of its lower energy. The difluorocarbenes are used as a monomer in the manufacturing of Teflon polymers.