Alkoxy-bridged complexes of copper(II) and nickel(II) with schiff bases of alcoholamines - including effects of structural distortion on the electronic spectra of Six-coordinate nickel(II) Complexes

Abstract

This paper describes the copper(II) complexes of the Schiff bases (eiLH 2) of 2-aminoethanol with acetylacetone benzoylacetone, dibenzoylmethane and ethyl acetoacetate, together with the copper(II) complexes of the Sehiff bases _(piLH 2) of 3-amino-l -propanolwith the above diones. Nickel(II) complexes are also described, using some eiLH 2 Schiff bases incorporating the first three diones. Measurements of molecular weight, mass and visible spectra and magnetic measurements down to ca. 9OK, are reported. The complexes [Cu(eiL)] 4 appear to be tetrameric, probably with oxygen-bridged cubane structures; they have room temperature μ eff values of ca. 1.9 B.M. and are weakly ferromagnetic. The complexes [Cu(piL)] 2 and [Ni(eiL)] 2 appear to have planar dimeric structures; the copper complexes have magnetic moments of ca. 0.6 B.M. and the nickel complexes are diamagnetic. Some paramagnetic alcohol adducts of the type [Ni(eiL)ROH] 4(R = Me, Et, n-Pr, n-Bu ) are assigned tetrameric cubane structures. These alcoholate complexes have μ eff values of ca. 3.3 B.M. at room temperature, and appear to be weakly ferromagnetic. The reflectance electronic spectra of the [Ni(eiL)ROH] 4 complexes are unusual in that they give evidence of marked tetragonal distortion, which appears to be produced by a structural distortion in the coordination environment of the nickel(II) ions. These spectra are compared with those of other, less distorted, nickel(II) tetramers.