Nickel(II)-Based Building Blocks with Schiff Base Derivatives: Experimental Insights and DFT Calculations

Néstor Novoa (1, 2, 3) , Carolina Manzur (2) , Thierry Roisnel (3) , Samia Kahlal (3) , Jean-Yves Saillard (3) , David Carrillo (2) , Jean-René Hamon (3)

1 Universidad de Concepción - University of Concepcion [Chile]
2 PUCV - Pontificia Universidad Católica de Valparaíso
3 ISCR - Institut des Sciences Chimiques de Rennes

We have recently reported a series of neutral square planar tridentate Schiff base (L) complexes of the general formula [(L)M(py)], showing relatively high first-order hyperpolarizabilities and NLO redox switching behavior. In the present study, new members of this family of compounds have been prepared with the objective to investigate their potential as building blocks in the on-demand construction of D-pi-A push-pull systems. Namely, ternary nickel(II) building blocks of general formula [(L-A/D)Ni(4-pyX)] (4-7), where L-A/D stands for an electron accepting or donating dianionic O,N,O-tridentate Schiff base ligand resulting from the monocondensation of 2-aminophenol or its 4-substituted nitro derivative and beta-diketones R-C(=O)CH2C(=O)CH3 (R = methyl, anisyl, ferrocenyl), and 4-pyX is 4-iodopyridine or 4-ethynylpyridine, were synthesized and isolated in 60-78% yields. Unexpectedly, the Sonogashira cross-coupling reaction between the 4-iodopyridine derivative 6 and 4-ethynylpyridine led to the formation of the bis(4-pyridyl) acetylene bridged centrosymmetric dimer [{(L-D)Ni}(2)(mu(2)-py-C equivalent to C-py)] (8). Complexes 4-8 were characterized by elemental analysis, FT-IR and NMR spectroscopy, single crystal X-ray diffraction and computational methods. In each compound, the four-coordinate Ni(II) metal ion adopts a square planar geometry with two nitrogen and two oxygen atoms as donors occupying trans positions. In 8, the Ni horizontal ellipsis Ni separation is of 13.62(14) angstrom. Experimental results were proved and explained theoretically exploiting Density Functional Theory calculations.

Mots clés: nickel; Schiff base complexes; Sonogashira cross coupling; X-ray crystal structure; DFT calculations

Domaines: Chimie

Néstor Novoa, Carolina Manzur, Thierry Roisnel, Samia Kahlal, Jean-Yves Saillard, et al.. Nickel(II)-Based Building Blocks with Schiff Base Derivatives: Experimental Insights and DFT Calculations. Molecules, 2021, 26 (17), pp.5316. ⟨10.3390/molecules26175316⟩. ⟨hal-03367751⟩