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An anion formed by removing the terminal proton of an alkyne, $\mathrm{RC}\equiv {\mathrm{C}}^{-}$. It can act as a carbon nucleophile, for example in addition to a ketone.

The conjugated aldehyde $\mathrm{C}{\mathrm{H}}_2=\mathrm{CHCHO}$. A carbon nucleophile can add at its carbonyl carbon or, in a conjugate addition, at the terminal beta carbon. Atom mapping distinguishes the two products.

An acyl chloride contains $\mathrm{R}-\mathrm{C}(\mathrm{O})\mathrm{Cl}$. Addition of a nucleophile and chloride elimination is a common substitution pathway.

Conjugate addition of a nitrogen nucleophile to an electron-poor alkene. Intramolecular addition can close a nitrogen-containing ring.

Base-promoted bimolecular acyl substitution: nucleophile addition gives a tetrahedral intermediate, then a leaving group departs from the acyl carbon.

Approach of a nucleophile opposite the leaving-group bond permits bond formation with inversion at the attacked tetrahedral carbon in an SN2 pathway.

Borazine dearomatization interrupts the planar pi system, for example when a nucleophile makes one boron tetrahedral. In a metal pi complex, this can change ring hapticity and produce a charged ligand with a different donor count.

Addition of bromine and an oxygen nucleophile across an alkene to form a bromoether. Intramolecular attack on a bromonium ion can close a ring; tether length, charge distribution and anti opening determine the resulting connectivity.

Oppositely charged ions remaining in direct contact without an intervening complete solvent shell. Their relative positions can bias substitution stereochemistry even when bond cleavage precedes nucleophile attack.

$\mathrm{C}{\mathrm{N}}^{-}$. Its carbon end can act as a nucleophile toward an alkyl leaving group to form a nitrile with one additional carbon.

Desilylation removes a silyl group. Attack by a nucleophile at silicon can pass through a pentacoordinate silicon arrangement before Si–O cleavage; the liberated oxygen may be trapped by a new electrophile.

Diisopropylethylamine is a sterically hindered tertiary amine base. It can remove protons and trap acid while competing relatively weakly as a nucleophile.

An electrophile accepts an electron pair in forming a bond. Reaction selectivity depends on both the electrophile and its interacting nucleophile.

The susceptibility of a species or atomic site to accepting an electron pair from a nucleophile. It depends on structure, charge and reaction conditions.

An oxocarbenium ion at the anomeric carbon of a cyclic glycosyl fragment. Positive charge is delocalized between that carbon and the ring oxygen. A counterion can remain nearby and influence which face a nucleophile approaches.

An organomagnesium reagent commonly written $\mathrm{RMgX}$, with organic group R and halide X. Its carbon group can act as a nucleophile; actual solution structures depend on solvent and aggregation.

Hexamethylborazine is ${\mathrm{B}}_3{\mathrm{N}}_3\mathrm{M}{\mathrm{e}}_6$, with one methyl on every ring atom. Its nitrogen atoms can form Lewis acid-base adducts, while nucleophiles can attack its boron atoms.

Metal ion catalysis uses a coordinated metal ion to activate a reagent, orient reactants or stabilize charge. Zinc can lower the acidity constant of coordinated water and support attack by the resulting oxygen nucleophile without a metal redox step.

Substitution of an alcohol using a phosphine and an azodicarboxylate reagent with a suitable acidic nucleophile. Carboxylate displacement normally inverts a stereogenic alcohol carbon; subsequent ester hydrolysis can unveil the inverted alcohol.

A nucleophile adds reversibly at the beta carbon to form an enolate, which is functionalized before elimination restores the alkene.