Abstract
Nickel(II) complexes containing 2,3,4 or 6 molecules of o-phenylenediamine, and a similar series of 4-saethyl-o-phenylenediamine complexes have been characterised by magnetic, infrared and electronic spectral, thermal analysis and X-ray powder photograph measurements. Some zinc and cobalt(II) complexes with 2 or 3 molecules of o-phenylenediamine and some copper(II) complexes with 1 or 2 molecules of diamine have also been characterised. Applying criteria for the detection of monodentate diamine based on C-N and N-H infrared stretching frequencies it has been established that all the complexes with either 2 or 3 ligand molecules contain only bidentate diamine, with the exception of the compounds, Ni(opd)3SO4, Co(opd)3SeO4.H2O, Zn(opd)3SeO4.H2O and Zn(opd)3SeO4. The 4:1 complexes appear to contain both mono and bidentate diamine whilst only monodentate diamine appears to be present in the 6:1 complexes. Electronic spectral measurements have enabled cis or trans configurations to be assigned to many of the nickel(II) complexes and an estimation of the ligand field strength of o-phenylenediamine to be made from the spectra of the nickel(II) tris-chelate complexes. Many of the 2:1 complexes prepared contain coordinated anions and in most cases a reduction of symmetry on coordination has led to the splitting of observed infrared bands. The donor behaviour of the selenate ion in this system generally resembles that of the sulphate ion. However, the nickel(II) complex, Ni(opd)2SO4 has a cis configuration whereas Ni(oiDd)2SeO4 is apparently a trans complex. Some preliminary work on complexes of p-phenylenediamine suggests that this ligand employs both amine groups in coordination giving rise to polymeric structures.