Properties of Some Compounds of the Metals of Medium Atomic Weight with Heterocyclic Ligands and the more readily Polarized Anions

Abstract

Part I The coordination behaviour of 2-benzoylpyridine (PhCOpy ) with some transition metal cations was investigated. 2-benzoylpyridine is believed to be a weak-field, bidentate (NO-co-ordination) ligand. Complexes of 2-benzoylpyridine with the perchlorates, chlorides, bromides and iodides of manganese (II), cobalt (II) and nickel (II) are described. Some compounds of zinc (II), cadmium (II) and magnesium (TI) were studied for comparison. With the exception of Mn (PhCOpy )X_ (X = Cl or Br) and Cd(PhCOpy) C15, all compounds isolated were bis-complexes but the metal ions are six-co-ordinate in all cases. The complexes, [Nn (PhCOpy){EtOH) 9] (C104 )o3 [Co(PhCOpy), (OH) 9] (C10, )o and [Ni (PhCOpy), (EtOH) 9] (C104) with ionic perchlorate groups, and [Co(PhCOpy) (C104) 9] and [Ni(PhCOpy), (C104) 9] with weakly coordinated perchlorate groups were characterised. In nitromethane, it was established that - [Co(PhCOpy ) Xo] (X = Cl or Br) dissociates to the pseudo-tetrahedral complex, [Co(PhCOpy )X.] . The two forms of Ni (PhCOpy ) C1, are believed to be the two isomers of the trans-dichloro-complex. [Mn(PhCOpy)X,] (X = C1 or Br) and [Cd(PhCOpy )C1.] are polymeric. The compounds M(PhCOpy oly. (M = Co, Ni, Zn or Cd) are isomorphous and form isomorphous groups with M(PhCOpy)oClo. {KM = Co, Ni(green and yellow)]. Part II The compounds investigated have al] been of one or the other of two types, namely [(pyridine base), (M)2*(13)] (M = first row divalent transition metal ion) or [(pyridine base), (wr ys* (CNSTy)o] »(M' = Ni(II)) only and pyridine base = pu iine B-picoline or y-picoline in both cases. Some I, compounds of manganese (II), iron (11), cobalt (II) and cadmium (11) with pyridine bases were crystallised from acetonitrile. Acetonitrile was retained as an uncoordinated, lattice component. W'? (B-picoline)(13)9 (M = Fe, Mn or Cd) could not be crystallised. Little information concerning the structure of the above compounds was obtained from physical examinations. The most informative data was derived from the measurement of the magnetic susceptibilities. High-spin octahedral complexes, [M(pyridine base), (15) 9] (M = Mn, Fe or Co) and planar or "tetragonally distorted octahedral" nickel (II) complexes, Ni(pyridine base )X [X = I, or (NCS-I5) J were characterised. Study of the magnetic susceptibilities at various temperatures is described for nickel (11) complexes only. The bonding nature of (CNS-I5) , as Ni-NCS-I, is discussed. The compounds Cd(py)a(13)o5 Cd(y-pic)a(I3)o 2(CH2CN) , and the polymerisation reactions involved in cadmium - y-picoline-iodine are described. The conductivity study of all compounds in nitromethane and in dimethylsulphoxide, and the absorption spectra of 13 ions in acetonitrile and in 1,2-dichloroethane are described.