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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.

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International audienceThe new ionic heterotrimetallic unsymmetrically-substituted Schiff base complex [Ni₍eta (5)-Cp)Fe(eta (5)-C5H4)-C(=O)CH=C(4-HO-C6H4)NCH2CH2N=CH-(2-O-(eta (6)-C6H4)Ru(eta (5)-Cp*)_][PF6] (3; Cp = C5H5 and Cp* = C-5(CH3)(5)) was prepared in 86% yield by a one-pot procedure by mixing equimolar amounts of 4-hydroxyphenyl functionalized ferrocenylenaminone 1, the organometallic aldehyde [(eta (5)-Cp*)Ru(eta (6)-2-HO-C6H4CHO)][PF6] (2) and nickel(II) acetate tetrahydrate in refluxing ethanol for 2 h. Its corresponding side-chain metallopolymer 4 was synthesized by reacting the organometallic-inorganic hybrid 3 with polyacrylic acid (DP = 25) in DMF at 110 A degrees C for 48 h with an equimolar quantity of N,N'-dicyclohexylcarbodiimide and a catalytic amount of 4-dimethylaminopyridine. The new complex 3 was characterized by FT-IR and multidimensional NMR spectroscopy, elemental analysis and mass spectrometry. Single crystal X-ray diffraction analysis of 3 showed that the ferrocenyl and [(eta (5)-Cp*)Ru](+) units exhibit an anti-conformation and are almost coplanar with the unsymmetrical Schiff base complex fragment, while the 4-HO-C6H4 plane is almost perpendicular. The four-coordinate Ni-II metal ion adopts a square planar geometry, with two nitrogen and two oxygen donor atoms that are mutually trans. Size-Exclusion Chromatography established that metallopolymer 4 is formed of approximately three pendant ionic trimetallic units, while Differential Scanning Calorimetry and Thermal Gravimetric Analysis indicated that 3 and 4 are thermally stable with decomposition temperatures that exceed or border to 250 A degrees C. Harmonic Light Scattering measurements at 1.91 A mu m incident wavelength showed that compounds 3 and 4 exhibit rather high second-order nonlinear responses, with hyperpolarizability beta (1.91) values strongly increasing on passing from the monomeric unit 3 to its metallopolymeric counterpart 4

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