Do you expect the carbon hydrides of the type (CnH2n + 2) to act as ‘Lewis’ acid or base? Justify your answer.
For carbon hydrides of type CnH2n + 2, the following hydrides are possible for
`n = 1 => CH_4`
`n = 2 => C_2H_6`
`n = 3 => C_3H_8`
For a hydride to act as a Lewis acid i.e., electron accepting, it should be electron-deficient. Also, for it to act as a Lewis base i.e., electron donating, it should be electron-rich.
Taking C2H6 as an example, the total number of electrons are 14 and the total covalent bonds are seven. Hence, the bonds are regular 2e–-2 centered bonds.
Hence, hydride C2H6 has sufficient electrons to be represented by a conventional Lewis structure. Therefore, it is an electron-precise hydride, having all atoms with complete octets. Thus, it can neither donate nor accept electrons to act as a Lewis acid or Lewis base.
Carbon hydrides of the type Cn H2n+2 are electron precise hydrides. Because they have atom with exact number of electrons to form covalent bonds. Thus, they do not behave as Lewis acid or base. Since they have no tendency to accept or lose electrons.