Doubly phenoxo-bridged M–Na (M = Cu(II), Ni(II)) complexes of tetradentate Schiff base: Structure, photoluminescence, EPR, electrochemical studies and DFT computation

Phenoxo-bridged complexes [M(μ-L)Na(ClO4)(CH3OH)] (M = Cu(II) (1) and Ni(II) (2)) (H2L = N,N′-bis(3-methoxysalicylidenimino)-1,3-diaminopropane, C6H3(OMe)(OH)-CH = N-(CH2)3-N = CH-C6H3(OMe)(OH)) are structurally characterised by single-crystal X-ray diffraction study. M(II) appears in the square-plane geometry with MN2O2 coordination sphere, while the sodium ion exists with NaO6 distorted octahedral environment. The molecules pack in the solid-state forming three-dimensional arrays through C–H- - -O, O–H- - -O, C–H- - -π, and π- - -π interactions. The spectral and redox properties are theoretically explained by DFT computation of optimised geometry of the complexes.

Graphical abstractN,N′-Bis(3-methoxysalicylidenimino)-1,3-diaminopropane [LH2 = C6H3(OMe)(OH)-CH = N-(CH2)3-N = CH-C6H3(OMe)(OH)] is a tetradentate N2O2 ligand forms heterometallic complexes [M(μ-L)Na(ClO4)(CH3OH)] (M = Cu (1), Ni(2)). Single-crystal X-ray diffraction studies reveal phenolato bridged, M(μ-L)Na, unit. The Cu(II)- - -Na(I) separation is 3.4318(14) Å in 1 and the Na(I) and Ni(II) centers in complex 2 are separated by 3.3793(11) (molecule 1) and 3.4289(11) Å (molecule 2). The complexes show M(III)/M(II) redox couple along with phenolato oxidation. Both the compounds were characterized by elemental analysis, IR, UV–Vis, EPR, photoluminescence and DFT computation study.Figure optionsDownload full-size imageDownload as PowerPoint slide