Derek P. Freyberg

Structures and Properties of the Copper(II) and Nickel(II) Complexes of NN′-bis[(2-hydroxy-5-methylphenyl)phenylmethylene]-4-azaheptane-1,7- Diamine and Related Compounds: Direct Comparison of D8 and D9 Analogues

The nickel(II), copper(II), and zinc(II) complexes of the quinquedentate ligands mbp and cbp, derived from the Schiff-base condensation of 3,3′-iminobis(propylamine) with 2-hydroxy-5-methylbenzophenone (mbp) and 5-chloro-2-hydroxybenzophenone (cbp), have been investigated by magnetic, spectroscopic, and X-ray crystallographic techniques and shown to be five-co-ordinate monomers, the Cu compounds having normal magnetic moments while the Ni complexes are high spin. The e.s.r. spectra of the Cu complexes show ligand hyperfine splitting for two of the three nitrogen donor atoms, in agreement with X-ray structural observations for [Cu(mbp)]. The metal environments are approximately distorted trigonal bipyramids, but the Cu complex has one elongated Cu-N bond, which suggests distorted square pyramidal geometry, and a weaker ligand-field than for the Ni complex. Failure to observe ligand hyperfine contribution by this nitrogen to the e.s.r. spectrum of [Cu(cbp)], in either frozen chloroform or solid solution in the (isomorphous) ZnII analogue, can be rationalised by the assumption that the Cu complex has essentially the same structure in the Zn lattice as in the pure Cu complex and in chloroform solution.Crystal structures for [Cu(mbp)] and [Ni(mbp)] were determined by the heavy-atom method from counter data, and refined by full-matrix least-squares: [Cu(mbp)], space group P, Z= 2, a= 10.073(2),b= 12.438(3), c= 13.080(3)A, α- 73.89(2), β= 67.54(1), γ= 86.99(2)°, R 6.3%. 2569 reflections; [Ni(mbp)], space group Pcnb, Z= 4. a= 16.927 (2), b= 24.232(2), c= 7.1562(7)A, α=β=γ= 90°, R 6.1%, 1271 reflections. The ZnII complex [Zn(cbp)] is isomorphous with [Cu(mbp)].

Structures and properties of zinc(II) complexes of NN-bis[(2-hydroxy-5-X-phenyl)phenylmethylene]-4-azaheptane-1,7-diamine (X = chloro or methyl): comparison of d10, d9, and d8 analogues

The zinc (II) complexes of the quinquedentate ligands derived from the Schiff-base condensation of 3,3′-iminobis (propylamine) with 5-chloro-2-hydroxybenzophenone (cbp) and 2-hydroxy-5-methylbenzophenone (mbp) have been synthesized and their crystal structures determined. [Zn(cbp)]· H2O Is crystallographically isomorphous with [Cu(mbp)] and the co-ordination environment of the zinc is a distorted trigonal bipyramid. The water molecule is disordered; it is remote from the metal atom and appears to produce no significant distortion of the complex. The striking differences between the related nickel(II), copper(II), and zinc(II) complexes must be ascribed mainly to the dn configuration of the metals. The metal environment in related nickel(II), copper(II), and zinc(II) complexes lies between trigonal bipyramidal and distorted square pyramidal, and progresses increasingly towards bipyramidal through the series Cu, Ni, Zn.Crystals of the zinc(II) complex with mbp were obtained as a hydrate [Zn(mbp)]·H2O with the water molecule probably hydrogen-bonded to a ligand atom, but with no apparent distortion due to the water molecule. The metal environment again approximates a trigonal bipyramid.The crystal structures were determined from full-matrix least-squares refinement of counter data ([Zn(cbp)]·H2O: space group P, Z= 2, a= 10.099(1), b= 12.500(2), c= 13.261(4)A, α= 74.57(3), β= 68.06(1), γ= 86.07(2)°, R= 0.036, 2 612 reflections; [Zn(mbp)] H2O : space group P21/c, Z= 4, a= 16.30(1), b= 10.178(4), c= 18.996(9)A, β= 71.79(9)°, α=γ= 90, R= 0.048, 2 669 reflections).