Interplay between Resonance‐Assisted Hydrogen Bonding and Coordination in Sulfo‐Functionalized Arylhydrazones of Active Methylene Compounds

The interaction of sodium(I) and copper(II) with sodium ( E,Z )‐2‐[2‐(1‐cyano‐2‐methoxy‐2‐oxoethylidene)hydrazinyl]benzenesulfonate (NaHL 1 ), sodium 4‐[2‐(2,4‐dioxopentan‐3‐ylidene)hydrazinyl]benzenesulfonate (NaHL 2 ), and sodium 2‐[2‐(2,4‐dioxopentan‐3‐ylidene)hydrazinyl]benzenesulfonate (NaHL 3 ) is studied on the basis of competition between intra‐ and intermolecular hydrogen bonding and coordination. The interplay between such interactions provides an unprecedented strategy towards an easy (( E , Z )→ E or Z ) isomeric resolution of NaHL 1 to give the new coordination polymers [Na(H 2 O) 2 (μ‐HL 1 )] n ( 1 ) ( E form) and [Na 2 (H 2 O) 4 (μ‐HL 1 ) 2 ] n ⋅ n H 2 O ( 2 ) ( Z form). It is also applied to the synthesis of the new compounds [Cu(H 2 O) 6 ](HL 2 ) 2 ⋅ 4 H 2 O ( 3 ) and [Cu(A)L 3 ] ⋅ H 2 O ( 4 ) (A=2‐(pyridin‐2‐yl)ethanol). The intra‐ and intermolecular structural relevance of hydrogen bonding is detailed by X‐ray diffraction.