Gerimário F. de Sousa

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.

Organotin(IV) Derivatives of 2-Acetylpyridine-N(4)-Phenylthiosemicarbazone, HAP4P, and 2-Hydroxyacetophenone-N(4)-Phenylthiosemicarbazone, H2DAP4P: Crystal and Molecular Structure of [SnMe2(DAP4P)] and [SnBu2(DAP4P)]

The reactions of 2-acetylpyridine-N(4)-phenylthiosemicarbazone, HAP4P, and 2-hydroxyacetophenone-N(4)-phenylthiosemicarbazone, H2DAP4P, with R4-mSnXm (m = 2, 3; R = Me, nBu, Ph and X = Cl, Br) led to the formation of hexa- and penta-coordinated organotin(IV) complexes, which were studied by microanalysis, IR, 1H-NMR and Mossbauer spectroscopies. The molecular structures of [SnMe2(DAP4P)] and [SnnBu2(DAP4P)] were determined by single-crystal X-ray diffraction studies. In the compounds [SnClMe2(AP4P)] and [SnBrMe2(AP4P)], the deprotonated ligand AP4P- is N,N,S-bonded to the Sn(IV) atoms, which exhibit strongly distorted octahedral coordination. The structures of [SnMe2(DAP4P)] and [SnnBu2(DAP4P)] revealed that the DAP4P2- anion acts as a O,N,S-tridentate ligand. In these cases, the Sn(IV) atoms adopt a strongly distorted trigonal bipyramidal configuration where the azomethine N and the two C atoms are on the equatorial plane while the O and the S atoms occupy the axial positions.

Organotin(IV) complexes of 4,6-dimethylpyrimidine-2-thione, Me2PymtH. Preparation, characterization and crystal structure determination of cis-[Ph2Sn(Me2Pymt)2] and [Ph3Sn(Me2Pymt)]

Abstract The coordination mode of the ambidentate ligand 4,6-dimethylpyrimidine-2-thione (Me2PymtH) was investigated with respect to the organotin(IV) compounds, namely Me2SnCl2, n-Bu2SnCl2, Ph2SnCl2 and Ph3SnCl. An X-ray crystal structure determination carried out on cis-[Ph2Sn(Me2Pymt)] (3) and [Ph3Sn(Me2Pymt)] (4) revealed that the Me2Pymt− ligand is N,S-coordinated in both complexes. The Sn(IV) atom is six-coordinated in 3 and five-coordinated in 4. The similarities observed in the IR, NMR (1H, 13C) and mass spectroscopy are indicative of a similar behavior of the ligand in all the complexes, thus suggesting a six-coordination in the dimethyltin (1) derivative and five-coordination in the dibutyltin (2) one. The complexes were characterized by means of elemental analysis, IR, NMR (1H, 13C) and mass spectroscopic methods.

New Heptacoordinated Organotin(IV) Complexes Derivatives of 2,6-diacetylpyridinebis(2-furanoylhydrazone), H2dapf, and 2,6-diacetylpyridinebis(2-thenoylhydrazone), H2dapt: Crystal and Molecular Structure of [Me2Sn(Hdapt]Br.H2O

The reaction of the ligands H2dapf and H2dapt, with R4-mSnXm (m = 2, 3; R = Me, Ph and X = Cl, Br) led to the formation of eight new heptacoordinated organotin(IV) complexes, which were studied by microanalysis, IR, NMR and Mossbauer spectroscopy to investigate their structural properties. The methyl derivative [Me2Sn(Hdapt)]Br.H2O was also studied by single crystal X-ray diffraction. It crystallizes in the monoclinic system, space group P21/c, with a = 21.920(3), b = 7.4470(5), c = 16.805(2) A, b = 110.18(1)o, Z = 4. The structure determination revealed a monocationic complex of Sn(IV) in a distorted bipyramidal geometry [Me2Sn(Hdapf)]+, with Br- as counter ion and one molecule of water helping the crystal packing. Mossbauer parameters of the complex [Me2Sn(Hdapf)]2[Me2SnCl4] have evidenced two Sn(IV) sites, as observed in the crystal structure determination. Also a correlation between Mossbauer and X-ray data based on the point-charge model is discussed.

Dependence on the reaction time of the coordination mode of 2,6-diacetylpyridine bis(2-furanoylhydrazone), H2dapf, towards ZnCl2. Crystal and molecular structures of [ZnCl(H2dapf)(H2O)]Cl · 4H2O and [Zn(dapf)]2

ZnCl2 reacts with the multidentate ligand 2,6-diacetylpyridine bis(2-furanoylhydrazone), H2dapf, to produce two complexes, [ZnCl(H2dapf)(H2O)]Cl · 4H2O and [Zn(dapf)]2, the predominant coordination mode of H2dapf being influenced by the reaction time. The mononuclear and binuclear complexes were prepared by refluxing DMF/H2O solutions of the reactants (1:1 molar ratio) for 3 and 6 h, respectively. The mononuclear complex possesses a distorted pentagonal bipyramidal (PBP) configuration, with the five ONNNO-donor atoms of the protonated H2dapf ligand in the pentagonal plane, with the water molecule and the chloride ion positioned in the axial position. The binuclear complex has two equivalent pseudo-octahedral ZnII centers, with the pyridyl nitrogen atoms of the two fully deprotonated ligands acting as bridges between the two metal atoms.

Synthesis and characterization of heptacoordinated tin(IV) complexes. X-ray crystal structure of [nBu2Sn(dappt)]·(Me 2CO)0.5 [H2dappt = 2,6-diacetylpyridine bis(4-phenylthiosemicarbazone)]

The reactions of the 2,6-diacetylpyridine bis(4-phenylthiosemicarbazone) ligand, H2dappt, with R4-mSnXm (m = 2, 3; R = Me, nBu, Ph and X = Cl) led to the formation of four new heptacoordinated organotin(IV) complexes, which were characterized by microanalyses and by IR and Mossbauer spectroscopies. The n-butyl derivative [nBu2Sn(dappt)]·(Me 2CO)0.5 was also analyzed by a single crystal X-ray diffraction study. It crystallized in the monoclinic system with a space group C2/c, with a = 36.164(14), b = 9.7050(15), c = 26.194(11) A, b = 132.00(2)o, Z = 8. The structure determination revealed a neutral complex of Sn(IV) in a distorted pentagonal bipyramidal (PBP) geometry, with the equatorial plane defined by the SNNNS donor system of the ligand and with the two n-butyl groups in the axial positions. Also, a correlation between Mossbauer and X-ray data based on the point-charge model is discussed.

A crystallographic study of (2-acetylpyridine-κN 4-phenylthyosemicarbazonate-κ2N1,S) methyl-trans-dichlorotin(IV)

AbstractThe preparation and characterization of [Sn(C14H13N4S)(CH3)Cl2], an organotin(IV) complex containing 2-acetylpyridine(4)-phenylthiosemicarbazone, is described. The molecular structure was studied by single crystal X-ray diffraction, and IR and Mössbauer spectroscopies. The title compound crystallizes in the centric triclinic space group, P

Rac-cis-1,2-bis(phenylsulfinyl)ethenebis(triphenylphosphine)-platinum(0), a novel Pt(0)-olefin complex: preparation, properties and molecular structure

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