Stanley E. Livingstone

Metal complexes of 2-mercaptobenzothiazole

SummaryMetal complexes of 2-mercaptobenzothiazole (LH) have been prepared and investigated. The metal complexes obtained were of the types ML2 (M = Ni, Pd, Pt, Zn, Cd), CuL.LH, and AgL. The copper complex has been shown to contain copper(I). Evidence from the i.r. spectra shows that in all the complexes the ligand is coordinatedvia the thiazole nitrogen and the exocyclic sulfur atom. Adducts of both the nickel and cadmium complexes were obtained with several nitrogen heterocycles. The complex CdL2py2 (py = pyridine) is isostructural with the six-coordinate NiL2py2 and CoL2py2 which possess acis configuration.

The magnetic moments and electronic spectra of lanthanide chelates of 2-thenoyltrifluoroacetone

SummaryMagnetic and spectral data are reported for the complexes LnL3 · 2H2O (Ln = lanthanide; LH = 2-thenoyltrifluoroacetone). The magnetic moments of the samarium and europium complexes are strongly temperature-dependent. The values of μeff for the other lanthanide chelates are close to those reported for other corresponding lanthanide compounds. The values of the Weiss constant θ for LnL3 · 2H2O (Ln = Gd, Tb, Dy, Ho, Er or Tm) are quite small (< 12 K), while those for Ln = Ce, Pr, Nd or Yb range from 29–104 K. The visible spectra of the complexes LnL3 · 2H2O (Ln = Pr, Nd, Sm, Dy, Ho, Er, and Tm) display the usual line-like absorption bands; hypersensitive transitions of Nd, Ho, Er and Tm complexes were observed with extinction coefficients many times greater than those found for the aqueous ions.

Lanthanide chelates of fluorinated ?-diketones. Part II magnetic moments and electronic spectra of lanthanide chelates of four fluorinated ?-diketones and the crystal structure of [Er(m MeC6H4CO=CHCOF3)3(H2O)2] H2O

SummaryMagnetic and spectral data are reported for the complexes Ln(RCO=CHCOCF3)3 ·nH2O (Ln=lanthanide; R=p BrC6H4,m-MeC6H4,o-MeC6H4, Bu-t; n=2 or 3). An x-ray crystal structure determination of Er(m-MeC6H4CO=CH-COCF3)3 · 3 H2O showed that the complex is eight-coordinate with three bidentate β-diketonato and two aquo ligands; the third water molecule is hydrogen-bonded to one of the coordinated water molecules. The configuration about the erbium atom approximates to a square antiprism. The magnetic moments of the samarium and europium chelates are temperature-dependent, whereas those of the other paramagnetic lanthanides obey the Curie-Weiss law. The visible spectra of the chelates of Pr, Nd, Sin, Eu, Tb, Dy, Ho, Er, and Tm display line-like absorption bands typical of lanthanide ions. Hypersensitive transitions were observed for Nd, Sm, Eu, Dy, Ho, and Er.

Chelate complexes of some NNO tridentate Schiff bases with iron(II), cobalt(II), nickel(II) and copper(II)

SummaryThe Schiff bases a-(C5H4N)CMe=NNHCOR (R = Ph, 2-thienyl or Me), prepared by condensation of 2-acetylpyridine with the acylhydrazines RCONHNH2, coordinate in the deprotonated iminol form to yield the octahedral complexes, M[NNO]2 M = Co or Ni; [NNOH] = Schiff base and the square-planar complexes, Pd[NNO]Cl. The Schiff bases also coordinate in the neutral keto form yielding the octahedral complexes (M[NNOH]2)Z2 (M = Ni, Co or Fe; Z = C104, BF4 or N03) and complexes of the type M[NNOH]X2 (M = Ni, Co, Fe or Cu; X = Cl, Br or NCS). Spectral and x-ray diffraction data indicate that the complexes M[NNOH]X2 (M = Ni or Fe) are polymeric octahedral, as are the corresponding cobalt complexes having R = 2-thienyl. However, the cobalt complexes Co[NNOH]X2 (X = CI or Br; R = Ph or Me) and the copper complexes Cu[NNOH]CI2 (R = Ph, 2-thienyl or Me) are five-coordinate, while the thiocyanato complex Co[NNOH](NCS)2 (R = 2-thienyl) is tetrahedral.

Metal chelates of ligands containing the ONS donor grouping, Part II. Metal chelates of schiff bases derived from β-diketones and α-N-Methyl-S-methyldithiocarbazate

SummaryThe Schiff bases RC(OH)=CHC(R′)=NNMeC(S)SMe (R = Ph,p-MeC6H4, R′ = Me; R = R′ = Ph) have been prepared by condensation of β-diketones with α-N-methyl-S-methyldithiocarbazate. By the loss of a proton they act as singly negatively charged tridentate ligands with oxygen, nitrogen and sulphur donor atoms (ONS). Iron forms the high-spin complexes [FeIII(ONS)2][FeIIICl4]. Copper(II), palladium(II), and platinum(II) yield the square-planar 1 : 1 complexes, M(ONS)CI (M = Cu, Pd, Pt) and Cu(ONS)NO3. Cobalt(II) and nickel(II) form high-spin, six-coordinate 1 : 2 complexes, M(ONS)2. For M = Ni and R = R′ = Ph, the complex is high-spin and octahedral, but when R = Ph orp-MeC6 H4 and R′ = Me, the complexes are diamagnetic and square-planar with nitrogen and sulphur (NS) coordinatio of the Schiff base, indicating that a change in the R′group can bring about a change in spin-state and stereochemistry of nickel.

Complex Halides of Palladium(II) and Platinum(II)

Abstract Methods of preparation are given for the complex halides K2PdCI4, K2PdBr4, K2PtCl4, and K2PtBr4.

Metal chelates of ligands containing the ONS donor grouping, part I. Metal chelates of Schiff bases derived from fluorinatedβ-diketones and thiosemicarbazide

SummaryThe Schiff bases RC(OFl)=CFlC(CF3)=NNlJC(S)NH2 (R = 2-thienyl, Ph,p-BrC6H4,p-MeC6H4,p-MeOC6H4,m-McOC6H4, β-naphthy], Pri) have been prepared by condensation of fluorinated β-diketones with thiosemicarbazide. By the loss of one or two protons from their tautomeric iminothiol form RC(OH)=CHC(CF3)=NN=C(SH)NH2 the Schiff bases act as (i) doubly negatively charged ONS tridentate or (ii) singly negatively charged NS bidentate ligands, respectively. The Schiff bases give dimeric µ2-dithiolo-bridged complexes M(ONS)2 (M = Ni, Pd, and Pt). The thiolo-bridges in the nickel complexes can be split by reaction with pyridine to give the monomeric compounds Ni(ONS)py, whereas the palladium and platinum complexes are unreactive towards pyridine. When R = 2-thienyl orp-BrC6H4, 1:2 complexes of the type M(HONS)2 (M = Pd or Pt) were isolated. With copper(II) the Schiff bases yield the complexes CuII(ONS). CuI(HONS) which are considered to have a polymeric structure involving σ-thiolo-bridges.

Dipole-moment measurements on metal chelate complexes. Part 1. Dipole-moment and dielectric-relaxation measurements on square-planar and octahedral metal complexes of seven mercapto-β-diketones

Dipole moments have been determined for iron(III), cobalt(III), nickel(II), palladium(II), platinum(II) and copper(II) complexes of the mercapto-β-diketones RC(SH):CH·C(O)R′[R = Me or Ph, R′= Ph; R = Me, C4H3S (2-thienyl), Ph. p-MeC6H4, or p-BrC6H4, R′= CF3] from both static-polarization and dielectric-relaxation measurements. The moments clearly indicate cis-square-planar configurations for the nickel, palladium, platinum, and copper complexes, but do not distinguish unequivocally between facial- and meridional-octahedral configurations for the iron and cobalt complexes. Group dipole moments for the R substituents, except 2-thienyl, in the square-planar complexes have been derived from the dipole-moment data. The effect of the CF3 group is discussed in terms of its influence on the electron density in the chelate ring.

Dipole-moment measurements on metal chelate complexes. Part III. Dipole-moment and dielectric-relaxation measurements on some tetrahedral zinc(II) complexes of seven mercapto-β-diketones

Dipole moments and relaxation times have been determined for tetrahedral zinc(II) complexes of the mercapto-β-diketones RC(SH):CH·C(O)R′[R = Me or Ph, R′= Ph; R = Me, C4H3S (2-thienyl), Ph, p-MeC6H4, or p-BrC6H4, R′= CF3] from both static-polarization and dielectric-relaxation measurements. Group dipole moments for the R substituents have been derived and found to agree with the corresponding values for a series of square-planar complexes studied earlier. Group dipole moments for the metal–chelate rings have been calculated by comparison of results obtained for the square-planar and tetrahedral complexes. The magnitude and direction of these ring moments are dependent on the presence of a CF3 group as R′ substituent.

Transition metal chelates of two ONNNO quinquedentate ligands

SummaryThe Schiff bases α,α-(RCONHN=CMe)2C5H3N (R = Ph or 2-thienyl) have been prepared by the condensation of 2-acetylpyridine with the substituted hydrazines RCONHNH2. By the loss of two protons from their iminol tautomers, these Schiff bases act as ONNNO quinquedentate ligands, forming the neutral complexes Met(ONNNO) (Met = Co, Ni, Cu, Zn, Cd or Pd). The zinc and cadmium complexes are monomeric and probably five-coordinate. The cobalt, nickel, and copper complexes are six-coordinate, presumably with an oxygen-bridged dimeric or polymeric structure. The structure of the palladium complex is not known.A uranyl complex UO2(ONNNO) was also obtained. An x-ray structural determination shows that the complex has a pentagonal bipyrimidal structure with the donor atoms of the quinquedentate Schiff base in the equatorial plane.