Syntheses, crystal structures and spectroscopy of di/tri/tetranuclear discrete and co-crystalline copper(II)-Na~I/Zn~(II)/Cd ~(II) complexes derived from a compartmental ligand: Inconsistency in the shifting of the copper(II) d-d band

摘要

The work in this report presents the syntheses, characterization, crystal structures and electronic spectra of the six heteronuclear complexes [Cu ~(II)L~1Na~I(μ-BF_4)_2Na ~IL~1Cu~(II)]·_2CH _3COCH_3 (1), [Cu~(II)L~1Na ~I(NO_3)(MeOH)] (2), [Cu~(II)L~1Zn ~(II)(H_2O)_2L~1Cu~(II)](ClO _4)_2 (3), [Cu~(II)(MeOH)L~1Zn ~(II)Cl_2] (4), [Cu~(II)L~1Cd II(H_2O)(MeOH)_2](ClO_4)_2 (5) and [Cu~(II)L~1Cd~(II)Cl_2(MeOH)][Cu~(II)(MeOH) L~1Cd~(II)Cl_2] (6), where H_2L 1 is N,N′-ethylenebis(3-methoxysalicylaldimine). The crystal systems and space groups are as follows: 1 and 2, triclinic, P1?; 3 and 6, monoclinic, P2_1/c; 4, orthorhombic, P2_12_12 1; 5, monoclinic, C2/c. While the N(imine)_2O(phenoxo) _2 compartment accommodates the copper(II) center, the larger and open O(phenoxo)_2O(methoxy)_2 compartment interacts with the second metal ion. Compounds 2, 4 and 5 are diphenoxo-bridged dinuclear systems, compound 3 is a trinuclear system in which the two Cu~(II)Zn ~(II) pairs are monophenoxo-bridged, compound 1 is a tetranuclear system in which two diphenoxo-bridged Cu~(II)Na~I units are interlinked by two tetrafluoroborate moieties, and compound 6 is a [2×1+2×1] co-crystal of two dinuclear Cu~(II)Cd~(II) units. The solid state electronic spectra of compounds 1-6 and also the mononuclear compound [Cu~(II)L~1(H_2O)] have been recorded in the range 400-800 nm. While correlating the d-d band position with the structural parameters and a previously proposed correlation, some inconsistency has been found, indicating that this area should be explored further.