Javier I. Beitia

Solid-state chemistry of nickel(II)-oxalate-amine systems. Synthesis, characterization and crystal structure of the bis(2,2′-bipyridine) (oxalato-O,O′)nickel(II) tetrahydrate

Abstract Purple single crystals of the mononuclear mixed-ligand complex [Ni(ox)(bipy)2]·4H2O, where ox is oxalate and bipy is 2,2′-bipyridine, were obtained by slow evaporation of a solution previously prepared by adding an ethanolic bipy solution to an aqueous solution of nickel(II) chloride hexahydrate and potassium oxalate monohydrate (molar ratio 1:2). The compound was characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction. The crystal structure consists of neutral mono-nuclear [Ni(ox)(bipy)2] units and crystallization water molecules which are held together by an extensive three-dimensional network of OH…O and CH…O hydrogen bonds and face-to-face stacking interactions between the π-systems of the bipy aromatic rings. The nickel atom is coordinated by two oxygen atoms of a bidentate oxalate ligand and four nitrogen atoms belonging to two bipy in an octahedral cis arrangement. Thermal decomposition of the complex was studied by TG-DTA techniques in synthetic air and argon atmospheres.

Preparation, chemical characterization and structural studies of 3-aminopyridinium salts of dithiooxalate ligand complexes, [M(S2C2O2)2]2− (M = NiII, PdII or PtII

Abstract The synthesis conditions, solid-state characterization and crystal structures of three 3-aminopyridinium salts of planar inorganic dithiooxalato complexes, (HC 5 H 6 N 2 ) 2 [Ni(S 2 C 2 O 2 ) 2 ] ( 1 ), (HC 5 H 6 N 2 ) 2 [Pd(S 2 C 2 O 2 ) 2 ] ( 2 ) and (HC 5 H 6 N 2 ) 2 [Pt(S 2 C 2 O 2 ) 2 ] ( 3 ), are described. The compounds have been characterized by elemental analysis and thermal, spectroscopic and X-ray diffraction methods. These complexes show a high thermal stability and the surrounding atmosphere is an important factor which significantly influences the course of the thermal decompositions as well as the final products. The IR and UV—vis spectra confirm the presence of the 3-aminopyridinium cations and the complex anions. X-ray diffraction analyses show that the compounds are isostructural and crystallize in the monoclinic space group P 2 1 / n with two molecules in the unit cell. The crystal and molecular structure of 2 was determined by single-crystal X-ray diffraction. The crystal structure consists of mixed layers of quasi-planar complex [Pd(S 2 C 2 O 2 ] 2− anions and 3-aminopyridinium cations linked by strong NH ⋯ O hydrogen bonds and anion—cation π—π interactions.

Syntheses and chemical, spectroscopic and structural study of 4-aminopyridinium salts of dithiooxalate ligand complexes, [M(S2C2O2)2]2− (M = NiII, PdII or PtII)

The synthesis conditions, the solid state characterization and the crystal structures of three 4-aminopyridinium salts of planar inorganic dithiooxalato anions, (C5H7N2)2[M(S2C2O2)2].2H2O where M = Ni(II), Pd(II) and Pt(II) (hereafter abbreviated as NIDT4AP, PDDT4AP, and PTDT4AP, respectively), are described. The compounds have been prepared by reaction of 4-aminopyridinium hydrochloride and the corresponding K2[M(S2C2O2)2] in aqueous solution, and then recrystallized in N,N-dimethylformamide. The compounds have been identified by using IR, thermoanalytical, and X-ray diffraction techniques. X-ray diffraction analyses of these compounds show that all of them are isostructural and crystallize in monoclinic system, space group C2/m, Z = 2. The crystal and molecular structure of compound PDDT4AP was determined: a = 10.462(1), b = 12.020(4), c = 9.207(1) A, β = 114.44(5)°, V = 1054.1(6) A3, Z = 2, F(000) = 576, μ = 12.866 cm−1, M = 572.98, Do = 1.80(1), Dx = 1.81 Mg·m−3, and λ(MoKα) = 0.71069 A. Final refinement led to R = 0.025 and wR = 0.030 for 1542 observed reflections with I > 3σ(I). The unit cell is made up of bis(dithiooxalato)palladate(II) anions and 4-aminopyridinium cations forming layers, and the water molecules occupy the space among them. In the crystal structure there are some significant π-π interactions between the aromatic cations and also dz2-π interactions between the metal ion of the complex anion and the planar cations. There is also an extensive hydrogen bond network. All these types of interactions ensure the lattice cohesiveness and give to the compound a tridimensional character.

Synthesis and chemical characterization of 2-methylpyridinium salts of planar nickel(II), palladium(II) and platinum(II) 1,2-dithiooxalato-S,S′ complexes. Crystal and molecular structure of bis(2-methylpyridinium) bis(1,2-dithiooxalato-S,S′)nickelate(II)

Abstract Microcrystalline powders of the complexes (HC6H7N)2[Ni(S2C2O2)2] (1), (HC6H7N)2[Pd(S2C2O2)2] (2) and (HC6H7N)2[Pt(S2C2O2)2] (3) were obtained by reaction of 2-methylpyridinium hydrochloride and the corresponding K2[M(S2C2O2)2] salts in aqueous solution. These compounds were characterized by elemental analysis, IR and UV-vis spectroscopies, thermal analysis (TG, DTG and DTA) and X-ray diffraction techniques. Single crystals of compound 1 were obtained by recrystallization in N,N-dimethylformamide and its crystal structure was determined from single-crystal X-ray diffraction. The crystal structure consists of mixed layers of quasi-planar complex [Ni(S2C2O2)2]2− anions and 2-methylpyridinium cations held together by electrostatic interactions, an extensive network of hydrogen bonds of the types NN ⋯ O and CH ⋯ O and anion-cation π-π interactions.

Preparation, chemical characterization and thermal study of 2-aminopyridinium salts of square-planar 1,2-dithiooxalato-S,S′ metal complexes (M NiII, PdII and PtII)

Abstract Reaction of an aqueous solution of 2-aminopyridinium chloride with the appropriate K 2 [M(S 2 C 2 O 2 ) 2 ] salt yielded microcrystalline powders of three complexes of the formulae (HC 5 H 6 N 2 ) 2 [Ni(S 2 C 2 O 2 ) 2 ] ( 1 ), (HC 5 H 6 N 2 ) 2 [Pd(S 2 C 2 O 2 ) 2 ] ( 2 ) and (HC 5 H 6 N 2 ) 2 [Pt(S 2 C 2 O 2 ) 2 ] ( 3 ), which were characterized by elemental analysis, IR and UV-vis spectroscopies, thermal analysis (TG, DTG and DTA) and X-ray powder diffraction techniques. The IR and UV-vis spectra support the presence of the aromatic cation and the complex anions. Single crystals of 1 were grown in silica hydrogel at room temperature employing test tubes. However, this compound is not stable on X-ray exposure and only the unit cell parameters were determined. The three compounds are isostructural, and crystallize in the monoclinic space group C 2/ c with Z = 8. Thermal studies give evidence that the mechanism and the final solid products are strongly influenced by the atmospheric conditions. The final decomposition products were identified by elemental analysis and the X-ray powder diffraction technique. In an argon-oxygen atmosphere, thermal degradation led to a mixture of nickel sulphide, oxides and sulphate for 1 , metallic palladium and palladium(II) oxide for 2 , and platinum(O) for 3 . Thermal decompositions in an inert atmosphere yielded nickel(II) sulphide, a mixture of Pd-PdS and metallic platinum, respectively.

Synthesis, chemical characterization and thermal behaviour of 1,2-dithiooxalato-S,S′ complexes of Ni(II), Pd(II) and Pt(II) with 2-amino-3-methylpyridinium

Abstract Three compounds of formula (HB) 2 [M(dto) 2 ], where HB + is 2-amino-3-methylpyridinium, dto 2− is 1,2-dithiooxalato- S,S ′ ligand, and M is Ni(II), Pd(II), or Pt(II), have been synthesized and characterized by elemental analysis, and infrared and UV—Vis spectroscopy. The thermal behaviour of these complexes was studied by thermogravimetry (TG) and differential thermal analysis (DTA) under argon and argon-oxygen atmospheres. The final products of the thermal decomposition were examined by elemental analysis and X-ray powder diffractometry. The IR and UV—Vis spectra indicate the presence of the aromatic cations and the complex anions. The thermal analytical data show that the starting compounds and the surrounding atmosphere significantly influence the course of the decomposition reactions, as well as the final products. In an oxidative atmosphere, a mixture of nickel(II, III) oxides and sulphides, palladium(II) oxide and metallic platinum were obtained, whereas in an inert atmosphere, nickel sulphides, palladium(II) sulphide and platinum(0) were identified as the final products.

Syntheses, chemical characterization, and thermochemistry of pyridinium salts of 1,2-dithiooxalato-S,S′ complexes of Ni(II), Pd(II) and Pt(II)

Abstract Three complexes of formula (HB) 2 [M(dto) 2 ] where HB + is pyridinium, M is Ni(II), Pd(II) or Pt(II), and dto 2− is 1,2-dithiooxalato- S,S′ (hereafter abbreviated as NIDTPY, PDDTPY and PTDTPY, respectively) have been synthesized and characterized by elemental analysis, IR and UV—vis spectroscopies and X-ray diffraction techniques. Thermal decompositions of compounds have been studied by thermogravimetry (TG and DTG) and differential thermal analysis (DTA) under argon-oxygen and argon atmospheres. The final decomposition products were identified by elemental analysis and the X-ray powder diffraction technique. Thermoanalytical data show that the surrounding atmosphere influences the course of the decomposition process, and the final products. In argon-oxygen atmosphere, the final residues were identified as a mixture of nickel sulphides, oxides and sulphate for the nickel compound, Pd(0) and PdO for the palladium compound, and platinum(0) for the platinum compound. Thermal decompositions in argon atmosphere yielded nickel(II) sulphide, a mixture of Pd/PdS, and metallic platinum, respectively.

4-methylpyridinium salts of planar nickel(II), palladium(II) and platinum(II) 1,2-dithiooxalato-S,S′ complexes. Preparation chemical characterization and thermal behaviour

Abstract Three salts of planar inorganic dithiooxalato complexes, (HB) 2 [Ni(dto) 2 ] ( 1 ), (HB) 2 [Pd(dto) 2 ] ( 2 ) and (HB) 2 [Pt(dto) 2 ] ( 3 ), where HB + is 4-methylpyridinium and dto 2− is the 1,2-dithiooxalato- S,S ′ ligand, were synthesized and characterized by elemental analysis, IR and UV-vis spectroscopies, thermal analysis (TG, DTG and DTA) and X-ray diffraction techniques. The IR and UV-vis spectra support the presence of the aromatic cation and the complex anions. The three compounds are isostructural and crystallize in the monoclinic space group P 2 1 / n . Thermal studies give evidence that the mechanism and the final solid products are strongly influenced by the atmospheric conditions. The final decomposition products were identified by elemental analysis and the X-ray powder diffraction technique. In an argon-oxygen atmosphere, the final residues were a mixture of nickel sulphides, oxides and sulphate for 1 , metallic palladium and palladium(II) oxide for 2 , and platinum(0) for 3 . Thermal decompositions in the inert atmosphere yielded nickel(II) sulphide, a mixture of Pd/PdS and metallic platinum, respectively.

Tetraphenylphosphonium 1,2-dithiooxalato-s,s′ complexes of nickel(II), palladium(II) and platinum(II). Synthesis, chemical characterization, spectroscopic and x-ray studies, and thermochemistry

Abstract Three salts of inorganic dithiooxalato complexes, (Ph4P)2[Ni(dto)2] (1), (Ph4P)2[Pd(dto)2] (2) and (Ph4P)2[Pt(dto)2] (3), where Ph4P+ is the tetraphenylphosphonium cation and dto2− is the 1,2-dithiooxalato-S,S′ ligand, were synthesized and characterized by elemental analysis, IR and UV-vis spectroscopies, thermal analysis (TG, DTG and DTA) and X-ray diffraction techniques. The IR and UV-vis spectra support the presence of the organic cation and the complex anions. The three compounds are isostructural and crystallize in the triclinic space group P 1 . The thermal analytical data show that the starting compounds and the surrounding atmosphere significantly influence the course of the decomposition reactions, as well as the final products. They were examined by elemental analysis and X-ray powder diffractometry. In an argon-oxygen atmosphere, a mixture of nickel(II, III) oxides and nickel(II) sulphide for 1, metallic palladium for 2 and platinum(0) for 3 were obtained, whereas under argon nickel sulphides, a mixture of Pd/PdS and metallic platinum were identified as the final products.

Structures of 2-amino-3-methylpyridinium bis(1,2–dithiooxalato-S,S')metallates(II) (M = Ni, Pd and Pt)

Three 2-amino-3-methylpyridinium salts of planar inorganic dithiooxalato anions, (C6HaNE)E[Ni(