Synthesis and spectral studies of iron(III) and cobalt(II) complexes of N(4)-phenylthio-semicarbazone with heterocyclic bases

Base adducts of iron(III) and cobalt(II) complexes containing salicylaldehy de N(4)-phenylthiosemicarbazone (H2L) and heterocyclic base(s) have been sy nthesized and characterized by IR, electronic and ESR spectra of the comple xes, as well as IR, electronic and H-1 and C-13 NMR spectra of the thiosemi carbazone. ESR studies of low spin cobalt(II) complexes indicate the presen ce of unpaired electron in the d(z)(2) orbital. Mossbauer spectrum of iron( III) complex in the polycrystalline state at 300 K reveals the existence of a quantum admixture of S=3/2 and S=5/2 states. Magnetic and spectroscopic data indicate a square planar structure for four-coordinate cobalt(II) comp lexes and square pyramidal geometry for five-coordinate iron(III) and cobal t(II) complexes.