John K. Swearingen

Spectral and structural studies of iron(III), cobalt(II,III) and nickel(II) complexes of 2-pyridineformamide N(4)-methylthiosemicarbazone

Abstract Reduction of 2-cyanopyridine by sodium in dry methanol in the presence of N(4)-methylthiosemicarbazide produces 2-pyridineformamide N(4)-methylthiosemicarbazone, HAm4M. Complexes with iron(III), cobalt(II,III) and nickel(II) have been prepared and characterized by molar conductivities, magnetic susceptibilities and spectroscopic techniques. In addition, the crystal structures of HAm4M, [Ni(Am4M)(OAc)], [Fe(Am4M)2]ClO4 and [Co(Am4M)2]ClO4 have been solved. Coordination is via the pyridyl nitrogen, imine nitrogen and thione or thiolato sulfur when coordinating as the neutral and anionic ligand, respectively.

Structural and spectral characterization of transition metal complexes of 2-pyridineformamide N(4)-dimethylthiosemicarbazone

Abstract Sodium in dry methanol reduces 2-cyanopyridine in the presence of N(4)-dimethylthiosemicarbazide to produce 2-pyridineformamide N(4)-dimethylthiosemicarbazone, HAm4DM. Complexes with iron(III), cobalt(III), nickel(II), copper(II), palladium(II) and platinum(II) have been prepared and characterized by spectroscopic techniques. In addition, the crystal structures of [Ni(Am4DM)(OAc)], [Ni(Am4DM)(CH3CN)]ClO4, [Cu(Am4DM)(OAc)] and [Pt(Am4DM)(DMSO)]Cl·2H2O are included. Coordination of the anionic thiosemicarbazone ligand is via the pyridyl nitrogen, imine nitrogen and thiolato sulfur atoms. The acetato groups in [Ni(Am4DM)(OAc)] and [Cu(Am4DM)(OAc)] are coordinated as monodentate ligands by one oxygen and the other oxygen interacts intermolecularly with the amide NH2 function of Am4DM. Coordination of the DMSO molecule in [Pt(Am4DM)(DMSO)]Cl·2H2O is through sulfur to give an essentially planar cation.

Structural and spectral studies of copper(II) and nickel(II) complexes of pyruvaldehyde mixed bis{N(4)-substituted thiosemicarbazones}

Abstract Pyruvaldehyde mixed bis(thiosemicarbazones) have been prepared in which the two thiosemicarbazone moieties have different N(4)-substituents. The mixed bis(thiosemicarbazones) and their copper(II) and nickel(II) complexes have been characterized with IR, electronic, mass, 1H NMR (Ni) and EPR (Cu) spectra. Representative crystal structures have been solved of nickel(II) complexes with either a pyruvaldehyde mixed bis(thiosemicarbazone) or a bis(thiosemicarbazone) with identical N(4)-substituents acting as a tetradentate ligand. [Ni(Pu4M4DE)] has an N(4)-methylthiosemicarbazone substituent on the keto “arm” and N(4)-diethylthiosemicarbazone substituent on the aldehyde arm. [Ni(Pu4M)] contains two N(4)-methylthiosemicarbazone moieties. Both bis(thiosemicarbazones) form square-planar N2S2 complexes with nickel(II) and copper(II).

Structural and spectral studies of a heterocyclic N(4)-substituted bis(thiosemicarbazone), H22,6Achexim·H2O, its heptacoordinated tin(IV) complex [Bu2Sn(2,6Achexim)], and its binuclear zinc(II) complex [Zn(2,6Achexim)]2

Abstract The multidentate ligand, 2,6-diacetylpyridine bis(3-hexamethyleneiminylthiosemicarbazone) monohydrate, H22,6Achexim·H2O, crystallizes with one thiosemicarbazone moiety in an intramolecular hydrogen bonded, bifurcated E′ form. The other thiosemicarbazone moiety is E and is not involved in intramolecular hydrogen bonding, but is involved in hydrogen bonding with the hydrate water molecule. The dianion (loss of N3a and N3b hydrogens) of H22,6Achexim acts as a pentadentate ligand, 2,6Achexim, in a planar conformation to a central tin(IV) ion, and as a bridging tetradentate ligand with the two thiosemicarbazone moieties of 2,6Achexim coordinating to different zinc atoms. The tin(IV) is heptacoordinate in a distorted pentagonal dipyramidal configuration, with the five SNNNS donor atoms of 2,6Achexim in the pentagonal plane and the two n-butyl groups in the axial positions. The binuclear zinc complex has two equivalent tetrahedral zinc centers, with the pyridyl nitrogens of the two ligands not coordinated.

Structural and spectral studies of di-2-pyridyl ketone N(4)-methyl- and N(4)-dimethylthiosemicarbazone and their metal complexes

Cobalt(II), nickel(II) and copper(II) complexes of di-2-pyridyl ketone N(4)-methyl- and N(4)-dimethylthiosemicarbazone have been prepared and characterized by physical and spectral methods. Use of different ligand-to-metal chloride molar ratios in the preparation of the complexes has produced both mononuclear and polynuclear species for the three metal ions. Crystal structures of the uncomplexed di-2-pyridyl ketone N(4)-methylthiosemicarbazone and a nickel(II) complex, di-2-pyridyl ketone N(4)-dimethylthiosemicarbazone, have been determined and aid the assignments of the i.r., n.m.r., u.v.–vis.–n.i.r. and e.s.r. spectra.

Trinuclear Palladium(II) Complexes with 2-Hydroxy-4-methoxyacetophenone N4-Dimethylthiosemicarbazone: Synthesis, Spectral Studies and Crystal Structure of a Tripalladium Complex

The synthesis and spectral characterization of a new triangular, trinuclear palladium(II) complex with the dianion of 2-hydroxy-4-methoxyacetophenone N4-dimethylthiosemicarbazone, 4MeOAp4Me is reported. The X-ray crystal structure determination of [Pd(4MeOAp4Me2)]3·DMSO shows it to contain a chair-type hexagon of alternating Pd and S atoms which form a molecular bowl. The crystal structure of H24MeOAp4Me2 shows that it is the E isomer with respect to the imine bond of the thiosemicarbazone moiety.

Iron(III), cobalt(II,III), copper(II) and zinc(II) complexes of 2-pyridineformamide 3-piperidylthiosemicarbazone

Abstract Reduction of 2-cyanopyridine by sodium in the presence of 3-piperidylthiosemicarbazide produces 2-pyridineformamide 3-piperidylthiosemicarbazone, HAmpip. Complexes with iron(III), cobalt(II,III) copper(II) and zinc(II) have been prepared and characterized by molar conductivities, magnetic susceptibilities and spectroscopic techniques. In addition, the crystal structures of HAmpip, [Fe(Ampip)2]ClO4, [Cu(HAmpip)Cl2]·CH3OH and [Zn(HAmpip)Br2]·C2H6SO have been determined. Coordination is via the pyridyl nitrogen, imine nitrogen and thiolato or thione sulfur when coordinating as the anionic or neutral ligand, respectively.

Spectral studies and X-ray crystal structures of three nickel(II) complexes of 2-pyridineformamide 3-piperidylthiosemicarbazone

Reduction of 2-cyanopyridine by sodium in dry methanol in the presence of 3-piperidylthiosemicarbazide produces 2pyridineformamide 3-piperidylthiosemicarbazone, HAmpip. Complexes with nickel(II) have been prepared and characterized by magnetic susceptibility and spectroscopic techniques. The crystal structures of [Ni(Ampip)2], [Ni(Ampip)OAc], and [Ni(HAmpip)Cl]Cl have been solved. Coordination of the anionic and neutral ligand is via the pyridyl nitrogen, imine nitrogen, and thiolato � / thione sulfur. [Ni(Ampip)2] is an approximately octahedral NiN4S2 center with the tridentate ligands in a meridonal arrangement. [Ni(Ampip)OAc] is essentially planar except for the acetato ligand, which is � /808 out of the coordination plane, and the ionic [Ni(HAmpip)Cl]Cl involves the neutral thiosemicarbazone ligand. # 2002 Published by Elsevier Science Ltd.

Structural and spectral studies of di-2-pyridyl ketone 3-piperidyl- and 3-hexamethyleneiminylthiosemicarbazone and their cobalt(II), nickel(II) and copper(II) complexes

Cobalt(II), nickel(II) and copper(II) complexes of di-2-pyridyl ketone 3-piperidyl- and 3-hexamethyleneiminyl-thiosemicarbazones (HDPypip and HDPyhexim, respectively) have been prepared and characterized by physical and spectral methods. Use of 1:2 thiosemicarbazone-to-metal chloride molar ratios in the preparation of the complexes has produced both mononuclear and polynuclear species for the three metal ions. Crystal structures of the HDPypip, HDPyhexim and [Ni(DPyhexim)Cl] have been determined and aid the assignments of the i.r., n.m.r., u.v.–vis. n.i.r. and e.s.r. spectra for the various complexes.

STRUCTURAL AND SPECTRAL STUDIES OF N-(2-PYRIDYL)-N'-TOLYLTHIOUREAS

Abstract N-(2-pyridyl)-N′- o -tolylthiourea, monoclinic, P2 1 /c, a =5.127(1), b =19.854(2), c=12.077(2) A , β =94.96(1)°, V=1224.7(2) A 3 , Z =4, μ=2.177 mm −1 , N-(2-pyridyl)-N′-m-tolylthiourea, triclinic, P−1, a =9.811(2), b =9.887(4), c=13.595(3) A , α =74.91(3), β =83.58(2), γ =76.27(2)°, V=1235.(7) A , Z =4, m=2.469 mm −1 and N-(2-pyridyl)-N′-p-tolylthiourea, triclinic,P−1, a =9.935(2), b =11.488(2), c=12.569(2) A , α =63.91(2), β =88.60(2), γ =75.04(2)°, V=1238.1(2) A 3 , Z =4, μ=2.154 mm −1 all have an intramolecular hydrogen bond between N′H and the pyridyl nitrogen, as well as intermolecular hydrogen bonding between NH and a thione sulfur of a second molecule to form centrosymmetric dimers. Solution 1 H NMR studies (CDCI 3 ) show the N′H resonance considerably downfield for each thiourea and its position, as well as that of NH, are affected by substituents on the phenyl ring.