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Unsymmetric Schiff‐base metalloligand precursor 2 is synthesized by condensation of phenol‐functionalized ferrocenylenaminone 1 with 2‐hydroxy‐5‐nitrobenzaldehyde. Heterobimetallic complexes 3 and 4 result from the N2O2‐tetradentate coordination of NiII and PdII metal ions with the doubly deprotonated form of 2, respectively. Linking 3 and 4 to polyacrylic acid through an esterification reaction leads to the formation of the corresponding side‐chain metallopolymers 5 and 6. The new compounds were fully characterized (IR, UV/Vis, NMR, MS, CV, SEC) and structures of 2–4 unequivocally determined by single‐crystal X‐ray diffraction techniques. Decomposition temperatures higher than 250 °C were found by DSC and TGA techniques for 3–6. Harmonic light scattering measurements showed that compounds 2–5 exhibit rather high second‐order nonlinear responses, between 200 × 10–30 and 970 × 10–30 esu, with the hyperpolarizability β1.91 value increasing significantly on passing from NiII complex 3 to its respective metallopolymer 5. The structural and electronic properties of 2–4 are analyzed by DFT and TD‐DFT calculations.

Oligomeric main-chain Schiff-base compounds 4 and 5 have been synthesized by the trans-esterification of their respective doubly functionalized monomeric precursors [M{(η 5 -The new compounds were characterized by elemental analysis, FTIR and multidimensional NMR spectroscopy, mass spectrometry, and cyclic voltammetry. Compounds 2, 3, and 6, the corresponding amide of 2, were characterized by X-ray structural investigation. Gel permeation chromatography estab-Scheme 2. Synthesis of the main-chain oligomers 4 and 5, and of the amide derivative 6.

Structural and NLO behavior of push–pull palladium(ii) complexes of metallocenyl-containing asymmetric Schiff base ligands.