Aza‐Michael addition is known to be one of the most exploited reactions in organic chemistry. Taking into account the fact that each seventh reaction in pharmaceutical industry involves the formation of at least one C−N bond, it is not surprising that this reaction is especially valuable for the synthesis of bioactive compounds and drugs. Traditionally, only push‐pull alkenes are regarded as starting material for this reaction. The participation of pull‐pull alkenes as Michael acceptors is much less studied. The presence of two vicinal electron‐withdrawing groups makes them highly reactive in nucleophilic reactions especially with nitrogen‐centered nucleophiles. This feature allows them to be excellent building blocks in the synthesis of bioactive molecules and polyfunctional materials. The review considers the most important and sometimes unexpected results obtained over the last two decades on the conjugate addition of nitrogen nucleophiles to pull‐pull alkenes bearing various acceptor moieties (alkoxycarbonyl‐, carbonyl‐, formyl‐, cyano‐, trifluoromethyl‐ or nitro group) in various combinations.

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The co-crystallization of the lead(II) complex [Pb(S2CNEt2)2] with tetraiodoethylene (C2I4) gave the co-crystal, [Pb(S2CNEt2)2]∙½C2I4, whose X-ray structure exhibits only a small change of the crystal parameters than those in the parent [Pb(S2CNEt2)2]. The supramolecular organization of the co-crystal is largely determined by an interplay between Pb⋯S tetrel bonding (TeB) and I⋯S halogen bonding (HaB) with comparable contributions from these non-covalent contacts; the TeBs observed in the parent complex, [Pb(S2CNEt2)2], remain unchanged in the co-crystal. An analysis of the theoretical calculation data, performed for the crystal and cluster models of [Pb(S2CNEt2)2]∙½C2I4, revealed the non-covalent nature of the Pb⋯S TeB (−5.41 and −7.78 kcal/mol) and I⋯S HaB (−7.26 and −11.37 kcal/mol) interactions and indicate that in the co-crystal these non-covalent forces are similar in energy.