A study of some nickel and copper diamine complexes and related compounds

Abstract

A number of simple and substituted ethylenediamine complexes of nickel(II) and copper(II) with various anions (chloride, bromide, iodide, perchlorate, thiocyanate, selenocyanate, tetraphenylborate, chloroplatinate(II), and chloroplatinate (IV)) have been prepared and some of their physical properties measured. Assignments of stereochemistry have been made on the basis of the spectral, magnetic, electrochemical and X-ray crystallographic measurements. The infrared absorption bands due to the thiocyanate and selenocyanate groups are reported and discussed in terms of the structures of the complexes. The different properties of the two compounds discussed; they contain cis and trans forms respectively of the same complex cation.An empirical rule that the NH2 rocking frequency in a series of ethylenediamine compounds decreases with increasing strength of the axial ligand field in relation to that of the in-plane field has been developed by deuteration studies.The visible spectra of the bis(2-methyl-1,2-diaminopropane)nickel(II) chloride, bromide and iodide have beenstudied over a temperature range and in a variety ofsolvents. The two species present in the solutionare the octahedral cis solvate species and the square-planar diamagnetic species. An estimate of thepercentage of the paramagnetic species present in theequilibrium at 24[degrees] has been made and the result confirmed by magnetic measurements. The temperature dependence of the magnetic susceptibility of has been studied. A spectrochemical series of solvents has been obtained by studying the solvent adducts and solution spectra of orange Lifschitz type (paramagnetic-diamagnetic) isomeric forms of have been prepared. The conclusion has been reached that paramagnetic diamagnetic isomers of Ni(Il) (diamine)2 complexes can be prepared with both N and C substituted diamines, providing the anion is of suitable co-ordinating ability. A general discussion of Lifschitz complex formation is included.