Question

Classify the following species as
(a) nuclephile,
(b) electrophile,
( c) both, or
(d) neither.
(1) `overset (oplus) N O_2`
(2) `RCH =0`
(3) `H_2`
(4) `SnF_4`
(5) `R - C -= ddot N`
(6) `CH_4`
(6) `Cr^4`
(7) `Cr^3`
(8) `BeF_2`
(9) `ddot N H_3`
(10) `I^(Ө)`
(11) `RCOO^(Ө)`
(12) `C_2 H_5 O^(Ө)`
(13) `BC1_3`
(14) `Br^(oplus)`
(15) `Br_2 C :`
(16) `SiC1_4`
(17) `Me_3 ddot P`
(18) `Me_2CH^(oplus)`
(19) `CH_2 = CH_4`
(20) `HC1`
(21) `Me_3 C^(ddot Ө)`.

Answer 1

a. Nucleophiles: 9,10,11,12,17,19, and 21
(9) `ddotNH_(3) (LP bar(e)s), (10) :overset(..)underset(..)I:^(Theta)` (negative charge with `LP bar(e)s), (11) RCOddotunderset(..)O:^(Theta)` (negative charge with `LP bar(e)s), (12) C_(2)H_(5)O^(Theta)` (negative charge with `LP bar(e)s),(19) CH_(2)=CH_(2)` (has two available `bar(e)s` in a `pi`-bond), `(21) Me_(3)C^(ddotTheta)` (negative charge with `LP bar(e)s)`
(b) Electrophiles : `1,4.7,8,13,14,15,16,18,` and `20`
(1) `NO_(2)^(o+) ( :ddot(O) =overset(o+)N=ddotO: )` (the electrophilic character completely masks the nucleophilic character of `LP bar(e)s` on `O` atom.)
(4) `SnF_4` (it has eight valence `overline e^, s`, but it can accept `LP overline e^, s` of a nucleophile by expanding its `d` shell to `12 overline e^,s)`
`SnF_(4) +2:ddot underset(..)F:^(Theta) rarr |SnF_(6)|^(-2)`
(7) `Cr^(3 +)` (positive charge)
(8) `BeF_2 (overline e` deficient, can accept `overline e^, s` from a nucleophile in its vaccant `p` orbital. Moreover, bonded `F` atoms are rarely nucleophilic.)
(13) `BC1_3 (overline e` deficient, six `overline e^, s`, can accept `overline e^, s` from a nucleophile to acquire stable octet)
`Br^(oplus)` (positive charge)
(15) `Br_2 C : (overline e` deficient, six `overline e^, s`, can accept `overline e^, s` from a nucleophile to acquire stable octet.)
(16) `SiC1_4` [same explanation as in `(13)`.]
(18) `Me_2 overset (oplus) CH` [same explanation as in `(13)`]
(20) `HC1` (Bronsted acid, can donate `H^(oplus)` which is `overline e` deficient)
( c) Both : (2) and (5) `(R - CH = O` and `R - C -= N)`
because `C` is `pi`-bonded to a high `EN` atom (`O` and `N`, respectively). So, `C` is an electrophilic site, and `O` and `N` with `LP overline e^, s` are nucleophilic sites.
(d) Neither : (3) and (6) ?`(H_2 , CH_4)` They can neither accept or donate `overline e^, s` , moreover, they do not have vaccant `p` or `d` orbital to accept `overline e^, s`.