Mercury(II) Compounds with 1,3-Benzothiazole-2-thione. Spectral, Thermal, and Crystal Structure Studies

Mercury(II) halides, HgX₂ (X = Cl^–, Br^–, I^–) react with 1,3-benzothiazole-2-thione (btztH) in methanol solutions giving the HgX₂(btztH) and HgX₂(btztH)₂ types of compounds. Mercury(II) acetate gives the thiolato compound Hg(btzt)₂ because of the deprotonation of btztH. Hg(btzt)₂ reacts with 2,2-bipyridine (bipy) giving a 1:1 complex. IR, ¹H, and ¹³C NMR spectral studies indicate that btztH acts as a monodenatate ligand through the S thione donor atom in all complexes. The X-ray crystal structure determinations of [HgI₂(btztH)]₂, HgBr₂(btztH)₂, Hg(btzt)₂, and Hg(btzt)₂(bipy) have been carried out revealing tetrahedrally coordinated mercury atom in [HgI₂(btztH)]₂ and HgBr₂(btztH)₂, while in Hg(btzt)₂(bipy) 2 + 2 coordination is achieved through strong Hg (N(bipy) contacts. A linear coordination in Hg(btzt)₂ is not affected by the Hg N contacts, which are longer than in Hg(btzt)₂(bipy), but still shorter than the van der Waals sum of mercury and nitrogen covalent radii. [HgI₂(btztH)]₂ exists as centrosymmetrical dimer with a Hg₂I₂ bridging core. The dimeric molecules are linked by the intermolecular hydrogen bonds between the terminal iodine atom and the NH group [3.63(1) Å] into infinite chains along the z-axis. There are N–H Br(bridging) intermolecular hydrogen bonds in HgBr₂(btztH)₂ joining molecules into endless chains along the x-axis. The Br(bridging) atom acts as double proton acceptor and two NH groups as proton donors [NH Br(bridging) 3.278(9) and 3.338(7) Å]. The mercury to sulfur and mercury to halogen bond distances in [HgI₂(btztH)]₂ and HgBr₂(btztH)₂ are discussed in relation to the analogous compounds, revealing strong influence of hydrogen bonds on their relative strengths as well as crystal packing requirements of the ligand. The sulfur and halogen atoms are more tightly bound to mercury implicating severe distortion of the coordination polyhedron in the structures in which they do not take part in hydrogen bonds formation. The influence of steric requirements of the ligands in Hg(btzt)₂ and Hg(btzt)₂(bipy) on the distortion of the mercury coordination polyhedra accompanied with the relative strength of Hg N contacts is considered.     

Gold(I) Pyrazolate Clusters: The Structure and Luminescence of the Tetranuclear, Base-Stabilized [(dppm)2Au4(3,5-Ph2Pz)2](NO3)2 ⋅ H2O

The tetranuclear Au(I) pyrazolate complex, [(dppm)₂Au₄(3,5-Ph₂Pz)₂](NO₃)₂  H₂O, 1, has been synthesized and structurally characterized. It is the first tetranuclear pyrazolate of Au(I) to have been found, although the trinuclear pyrazolates of Au(I) are well known. Complex 1 exhibits luminescence at 77 K when excited at 333 nm with an emission maximum at 454 nm. The emission has been assigned to ligand to metal charge transfer, LMCT, based upon the vibronic structure that is observed. The complex crystallizes in the monoclinic space group P2₁/c, with a=19.33(3) Å, b=20.26(3) Å, c=19.80(3) Å, =106.74(2)°, V=7425(17) ų, Z=8, and R=0.058. The Au    Au distances are Au(1)    Au(4)=3.185(3) Å, Au(1)    Au(2)=3.230(3) Å, Au(2)    Au(3)=3.079(3) Å, and Au(3)    Au(4)=3.280(3) Å.     

An Inorganic-Organic Hybrid Supramolecular Hydrogen-Bonding and π-π Stacking Network Containing Ge4S4− 10 Cluster: Synthesis and Characterization of (H2bipy)2Ge4S10⋅(bipy)⋅7H2O (bipy=4,4′-bipy)

The reactions of TMA₄Ge₄S₁₀ (TMA=tetramethylammonium), Cu(NO₃)₂3H₂Oand 4,4-bipy under hydrothermal environment result in the formation of (H₂bipy)₂Ge₄S₁₀(bipy)7H₂O (1), which has been structurally characterized by single crystal X-ray analysis. The 3-D structure of 1 can be viewed as an inorganic-organic hybrid supramolecular hydrogen-bonding (hydrogen bonds: O–HO, N–HN, C–HO, N–HO, and O–HS) and - stacking network containing Ge₄S^4– ₁₀ clusters and novel [H₂bipybipyH₂bipy] trimers.     

Crystal Structure of [Co?6H2O][Co?4H2O?2Gly]?2SO4

The crystals of [Co6H₂O][Co4H₂O2Gly]2SO₄ were studied by X-ray diffraction analysis (triclinic, P , a = 5.975(5), b = 15.469(5), c = 6.765(5) , =120.71(5), =83.23(5), =98.77(5)°). The structure contains complex cations of two types: [Co6H₂O]²⁺ and [Co4H₂O2Gly]²⁺ and SO ₄ ^2– anions linked by hydrogen bonds and electrostatic forces. Three chemically nonequivalent charged layers can be distinguished in the structure: one layer is formed by cobalt hexaaqua complexes, another by [Co4H₂O2Gly]^2– complexes, and the third layer consists of sulfate anions interlaying the former two. The layers alternate along the b axis and are connected by a 3D system of hydrogen bonds.     

Thermal and BF<Subscript>3</Subscript>⋅Et<Subscript>2</Subscript>O-catalyzed cleavage of 1-hydrohexafluoroisobutenyloxytrimethylsilane. Perfluoromethacrolein,its isomers,dimers, and homopolymers

During vacuum pyrolysis in a quartz or steel tube, 1-hydrohexafluoroisobutenyloxytrimethylsilane (1) eliminates fluorotrimethylsilane to give perfluoromethacrolein, which was detected by NMR. Similar pyrolysis of silane 1 over KF results in E- and Z--hydrotetrafluoromethacryloyl fluorides. At 20 °C, perfluoromethacrolein undergoes homopolymerisation and/or cyclodimerization to yield 4,4-difluoro-2-pentafluoroisopropenyl-5-trifluoromethyl-4H-1,3-dioxin, which rearranges into E-7,7,7-trifluoro-2,6-bis(trifluoromethyl)-4-oxahepta-2,5-dienoyl fluoride under the action of BF₃Et₂O. The same fluoride is also formed, together with fluorotrimethylsilane, directly from silane 1 under the action of BF₃Et₂O.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1629–1635, August, 2004.Deceased     

Gold(I) Formamidinate Clusters: The Structure, Luminescence, and Electrochemistry of the Tetranuclear, Base-Free [Au4(ArNC(H)NAr)4]

The structures of the tetragold(I) formamidinate cluster complexes, [Au₄(ArNC(H)NAr)₄], Ar=C₆H₄-4-OMe (1), C₆H₃-3,5-Cl (2), C₆H₄-4-Me (3), have been characterized by x-ray crystallography. The range of AuAu distances is 2.8–3.0 Å. The angles at AuAuAu are acute and obtuse 70 and 109°, 88 and 91°, and 63 and 116° in 1, 2, and 3, respectively. The four gold atoms are located at the corner of a rhomboid with the formamidinate ligands bridged above and below the near plane of the four Au(I) atoms. The tetranuclear gold(I) complexes show a bright blue-green luminescence under UV light, with an emission at 490 nm and a weak emission at 530 nm in the solid state, at room temp and 77 K. The oxidation of the formamidinate cluster, 1, has been studied electrochemically in 0.1 M Bu₄NPF₆/CH₂Cl₂ at a Pt working electrode with different scan rates. Three waves were obtained, 0.75, 0.95, and 1.09V vs. Ag/AgCl at a scan rate of 500 mV/s, the three waves are reversible. The potentials are independent of the scan rate in the range 50 mV/s to 3 V/s. The current at the third wave is larger than those at the first two.     

Study of acid-base interactions of mono- and diazaporphyrin indium complexes with acetic and trifluoroacetic acids by <Superscript>1</Superscript>H NMR and electronic spectroscopy

Indium complex of 13,17-dibutyl-2,3,7,8,12,18-hexamethyl-5-azaporphyrin (Cl)InMAP was synthesized, and acid-base interactions of the meso-nitrogen atoms in (Cl)InMAP and its diaza analog (Cl)InDAP with acetic and trifluoroacetic acids were studied by ¹H NMR and electronic spectroscopy. Depending on the medium, the complexes and proton-donor species HA give rise to acid solvates >N(HA)_n which are converted to final acid-base interaction products, H-complexes >NH+A^–(HA)_m or ionic associates >NH⁺A^–(HA)_l , as the acidity of the medium rises. In acetic acid solution, the acid solvates derived from more basic (Cl)InMAP exist in equilibrium with the H-associates (pK _a1 = 4.45±0.03). From (Cl)InDAP, the corresponding H-associates are formed only in the presence of H₂SO₄ (pK _a1 = 2.10±0.03). In more polar media (solutions of trifluoroacetic acid in methylene chloride), ionic associates are formed, which involve one [(Cl)InMAP, pK ₁ = 2.46±0.02] or two meso-nitrogen atoms [(Cl)InDAP, pK ₁ = 2.11±0.03, pK ₂ = 0.41±0.04).Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 9, 2004, pp. 1546–1556.Original Russian Text Copyright © 2004 by Stuzhin, Ivanova, Migalova.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis and Structures of the Novel Pyridoxal Oxime Derivatives

Novel pyridoxal oxime derivatives were prepared and characterized by means of IR, ¹H and ¹³C NMR spectroscopy. The crystal structures of the 3-hydroxy-4-hydroxyiminomethyl-5-hydroxymethyl-1,2-dimethylpyridinium iodide 1 and 3-hydroxy-4-hydroxyiminomethyl-5-hydroxymethyl-1,2-dimethylpyridinium chloride monohydrate 2 were determined by X-ray analysis. The both compounds crystallize in the triclinic crystal system, space group P . Crystal data: 1 a = 6.286(2) Å, b = 8.748(4) Å, c = 11.736(4) Å, = 104.02(3)°, = 94.70(3)°, = 107.44(6)°, V = 589.0(4) ų, Z = 2, R = 0.0526; 2 a = 6.8980(5) Å, b = 8.6409(6) Å, c = 11.1777(6) Å, = 111.138(5)°, = 93.114(6)°, = 105.158(5)°, V = 591.57(7) ų, Z = 2, R = 0.0492. The bond distances and angles in both structures agree very well. The main difference between these structures was observed in the orientation of the hydroxymethyl group with respect to the pyridinium ring. In the both structures intramolecular hydrogen bond forming six-membered ring were observed. The intermolecular OsI hydrogen bonds in the crystal structure of the compound 1 form dimers. In the crystal structure of compound 2, the water molecules and chlorines build eight-membered rings, which are also connected to pyridinium cations by OsCl and OsO intermolecular hydrogen bonds forming a three-dimensional network.     

Synthesis and properties of nicotinic acid derivatives containing a 2,2,6,6- tetramethylpiperidine 1-oxyl residue

N¹-(Nicotinoyl)-N²-4-(2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl)hydraxine was obtained by condensation of nicotinoyl hydrazide with 2,2,6,6-tetramethyl-4-oxopiperidine 1-oxyl. Acylation of 2,2,6,6-tetramethyl-4-hydroxypiperidine 1-oxyl with nicotinoyl chloride gives nicotinic acid 2,2,6,6-tetramethyl-1-oxyl 4-piperidyl ester. A spin-labeled analog of nicotinamide was obtained by condensation of nicotinoyl azide with 4-amino-2,2,6,6-tetramethylpiperidine 1-oxyl. The synthesis of 1-N-(-D-ribofuranoside)-3'-N[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)pyridinecarboxamide from 2,2,6,6-tetramethyl-4-nicotinoylaminopiperidine 1-oxyl and 2,3,5-tri-O-benzoyl--D-ribofuranosyl bromide proceeds without damage to the iminoxyl radical. The preparation of the corresponding spin-labeled nucleotide is hindered by destruction of the iminoxyl radical during ion-exchange chromatography.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 352–355, March, 1976.     

Thermal,FTIR and XRD study on some 1:1 molecular compounds of theophylline

Thermal stability and structural features of three newly synthesized 1:1 lattice compounds of theophylline (th) with ethylenediamine carbamate (enCO₂), 1,10-phenanthroline (phen), and 5-sulfosalicylic acid (sa-5-SO₃H) have been studied in comparison with those of the theophylline compounds with ethanolamine (ea) and salicylic acid (sa). Simultaneous TG-DTA measurements, FTIR spectroscopy and X-ray diffraction have been carried out to get information on the various structural units of these solid inclusions, especially on the actual form (molecule, anion or cation) of theophylline moieties built in. Theophyllinate and theophyllinium ions have been found in the ethanolammonium-theophyllinate (1:1) (1, eaH⁺th^-) and the theophyllinium salicylic acid 5-sulfonate monohydrate (1:1:1), (5, thH⁺saSO_–³H₂O), respectively. Whilst the 1:1 complexes with 1,10-phenanthroline (2, thphen), ethylenediamine carbamate (3, thenCO₂), and salicylic acid (4, thsa) contain neutral theophylline moieties associated with H-bonds. In compound (3) the zwitterion of N-(2-ammonium-ethyl)carbamate (NH₃⁺-CH₂-CH₂-NH-CO_-²) is present.This revised version was published online in November 2005 with corrections to the Cover Date.     

Molecular Structure of Silicon Tetraiodide

The molecular geometry of silicon tetraiodide was determined by gas-phase electron diffraction at 378 K. The molecule has a regular tetrahedral shape with an Si—I bond length (r _g) of 2.432(5) Å and an II nonbonded distance (r _g) of 3.971(8) Å. There is an apparent anharmonicity in both the stretching and the bending vibrations, with the latter especially pronounced.     

Optical Spectroscopy of Hybrid Sol-Gel Coatings Doped with Noble Metals

Sol-gel coatings in the xM (100-x) SiO₂ system, (M = Cu, Ag and Au) x =0.1–10 mol%), are deposited on soda lime glass slides by using silicon tetramethoxide Si(OCH₃)₄) and methyltriethoxysilane (SiCH₃[OCH₂CH₃]₃) as silica precursors. Anhydrous CuCl, CuCl₂ 2H₂O, Cu(NO₃)₂ 3H₂O, CuSO₄ 5H₂O, AgNO₃ and HAuCl₄ 3H₂O are used as copper, silver and gold sources. Coatings with thicknesses ranging from 100 to 900 nm are deposited on the subs trates by dip-coating and subsequently densified at 500°C for 1 h in air. Spectroscopic studies of the coatings as a function of the thicknesses and the metal concentration are carried out by photoluminescence (PL) and optical absorption (OA). In addition, direct observations of some gold coatings were performed by transmission electron microscopy (TEM). Results indicate that for silver and copper containing coatings the excitation and emission spectra arise from electronic transitions in Ag⁺ and Cu⁺ ions and no significant absorption bands due to colloidal precipitation are observed. Gold containing coatings show purple coloration due to an absorption peaking in the 520–560 nm range, which is characteristic of gold colloids. The presence of these colloids is confirmed by TEM observations.     

Crystal structure of 1-(2-pyridiniomethyl)-2,4-<Emphasis Type="Italic">bis</Emphasis>(phenylsulfonyl)benzene bromide

The crystal structure of 1-(2-pyridiniomethyl)-2,4-bis(phenylsulfonyl)benzene bromide, (C₂₄H₂₀NO₄S₂)⁺. Br^– (I) has been investigated by X-ray diffraction (XRD)analysis. The triclinic structure of I (space group P1, a = 7.863 , b = 8.350 , c = 9.043 , = 94.00°, = 97.81°, = 104.62°, Z = 1) was solved by direct methods and refined by full-matrix least-squares analysis in an anisotropic approximation to R = 0.048 for all 4570 reflections collected (CAD-4 automatic diffractometer, CuK ). The geometrical parameters of the organic cation were determined with a sufficient degree of accuracy. The crystal structure of I involves a very strong interionic hydrogen bond N⁺-HBr^–.Original Russian Text Copyright © 2004 by A. N. ChekhlovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 759–763, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Structure of decaazonium Tricyclo[28.2.2.213.16]tetratriacontane Decatetrafluoroborate Decahydrate

A new inclusion complex, decaazonium tricyclo[28.2.2.2^13.16]tetratriacontane (L) decatetrafluoroborate decahydrate [(H₁₀L)(BF₄)₁₀10H₂O] (I), has been prepared and characterized by X-ray crystallography. Crystal data: a = 8.156(2), b = 29.125(6), c = 12.981(3) , = 96.76(3)°, space group P2₁/c, Z = 2, the final R = 0.0662 for 5376 reflections with I> 2 (I) (MoK radiation). The azamacrocycle of the complex is a 10-charged cation. The components of the supramolecular system in crystal are stabilized by the hydrogen bonds between the macrocycle cations, the water molecules, and the tetrafluoroborate anions. The water molecules make a solvation shell of the macrocycle forming an octahydrate. The tetrafluoroborate anions alternate with the water molecules stitched to the macrocycle, forming polymer chains in the directions parallel to the z axis of the crystal, and serve as bridges between the macrocycle cations related by the c plane. The set of hydrogen bonds including weak ones unite the components of the complex into a three-dimensional framework. All tetrafluoroborate anions in the structure are disordered.     

1:1 and 1:2 Complexes of Mercury(II) Halides with 1,3-Thiazolidine-2-thione. Spectral, Thermal, and Crystal Structure Studies

The series of compounds of the general formulae HgX₂(tzdtH) and HgX₂(tzdtH)₂ (X = Cl, Br, I; tzdtH = 1,3-thiazolidine-2-thione) have been prepared, as well as Hg(tzdt)₂. IR, ¹H, and ¹³C NMR spectral data of the complexes indicate thione donation, which is confirmed by the crystal structure analyses of [HgBr₂(tzdtH)]₂, [HgI₂(tzdtH)]₂, and HgI₂(tzdtH)₂. The structures of [HgBr₂(tzdtH)]₂ and [HgI₂(tzdtH)]₂ consist of centrosymmetric doubly bridged dimers, but they are not isostructural. The asymmetry in the HgX₂Hg bridge is more pronounced in the bromo than in the iodo derivative [S–Hg–X(terminal) is 138.19(9)° for X = Br and 123.49(10)° for X = I], which is accompanied by the stronger Hg–S covalent bond in the bromo than in the iodo complex [2.435(4) vs. 2.510(3) Å]. The Hg–X(bridging) (X = Br, I) bond distances are shorter than the sum of van der Waals radii for mercury and X. Dimeric centrosymmetric complex units are held together only by van der Waals forces in [HgI₂(tzdtH)]₂, while in [HgBr₂(tzdtH)]₂ there is an intramolecular hydrogen bond of N–H Br type (3.34(1) Å). HgI₂(tzdtH)₂ exists as a mononuclear tetrahedral complex with two long Hg–S [2.672(1) Å] and two short Hg–I bond distances [2.688(1) Å] related by a twofold axis. The molecules of HgI₂(tzdtH)₂ are linked into infinite chains along the c axis by intermolecular N–H S [3.38(1) Å] hydrogen bonds.     

Molecular Encapsulation of Half-Sandwich Complexes of Iron with Cyclodextrins: New Laminar Materials

The treatment of - and -cyclodextrins with the half-sandwich complexes of iron afford the inclusion compounds CpFe(L₂)XCD ( and ) (X = Cl, I; L = CO; L₂ = dppe, dppe = (Ph)₂P(CH₂)₂P(Ph)₂), [CpFe(L₂)L-]PF₆CD ( and ) L- neutral donor ligands and[(Cp(dppe)Fe)₂-µ-CN]PF₆2CD ( and ). The inclusion compounds [Cp(dppe)Fe-NCCH₃]PF₆-CD and [Cp(dppe)Fe-(¹-dppm)]PF₆-CD have a laminar structure. The - and -cyclodextrin encapsulation effect on the electro-oxidation of the binuclear complex was studied using cyclic voltammetry.The electron-transfer reactions associated with the oxidation of the two different N-bonded and C-bonded organometallic fragments are substantially affected by and encapsulation.     

Thermal Behaviour of Metal Complexes of 6-(2-Pyridylazo)-3-acetamidophenol

The present work aims chiefly to study the thermal behaviour of complex compounds with general formula: [M(HL)xH₂O](A)yH₂O (where HL=C₁₃H₁₁N₄O₂=6-(2-pyridylazo)-3-acetamidophenol (PAAP), M=Cu(II), Zn(II), Cd(II) and Fe(III) x=1, 3; y=2, 5) while A=CH₃COO^– (Ac), Cl₂. The second formula is [M(H₂L)xH₂O]Cl₂yH₂O, (where H ₂ L=C₁₃H₁₂N₄O₂ (PAAP), M=Ni(II), Co(II) x=3; y=4, 6). The compounds were identified by elemental analysis, FT-IR spectra and TG/DTG,DTA methods. It was found that during the thermal decomposition of complex compounds water molecules of crystallization are released in the first step. In the next step the pyrolysis of organic ligand takes place. Metal oxide remained as a solid product of the thermal decomposition. Mass spectroscopy has been used for the determination of the thermal decomposition on the intermediate products. It was found that the thermal stability of the studied compounds increases as the ionic radii decreases. The activation energy E, the entropy change S ^*, the enthalpy H ^* change and Gibbs free energy change G ^* were calculated from TG curve.This revised version was published online in November 2005 with corrections to the Cover Date.     

Synthesis and Characterization of Cobalttelluride Clusters with the Cubic Body-Centered Co9Te6(CO)8 Core

Reduction of Cp₂NbTe₂H (Cp=tBuC₅H₄) with CH₃Li results in a red-violet solution which reacts with Co₂(CO)₈ to give the neutral cluster {Cp₂Nb(CO)}₂[Co₉Te₆(CO)₈] (2) and a mixture of salts, from which [Na(THF)₆][Co₉Te₆(CO)₈] (4) was obtained by crystallization from THF in very poor yield, probably due to Na impurities in CH₃Li. Clusters 2 (123 valence electrons) and 4 (122 valence electrons) possess hexacapped cubic Co@Co₈ cores. The structure of 2 was identified by comparison of spectroscopic data with those of parent clusters: Two Cp₂Nb(CO) fragments are fixed at two opposite ₄-Te bridges of the Co₉Te₆(CO)₈ skeleton. A crystal structure determination of 4 shows this compound to contain discrete ions. Nearly equal diameters of ca. 10.5Å for the [Co₉Te₆(CO)₈]^– anion and the octahedral [Na(THF)₆]⁺ cation as well as electrostatic interactions between them and attractive C–HO contacts may be responsible for the formation of layers throughout the crystal.     

The Missing Link in Low Nuclearity Pure Polyoxovanadate Clusters: Preliminary Synthesis and Structural Analysis of a New {V16} Cluster and Related Products

Two new metastable polyoxovanadate-based cluster compounds have been isolated and crystallographically characterized with nuclearities of {V₁₆} (1) and {V₁₈} (2). The {V₁₆} cluster represents a new framework type and incorporates two protons into the cluster framework whereas the {V₁₈} framework has been previously characterised, and the oxidation states of the {V₁₈} cluster can be assigned as {V^IV ₁₅V^V ₃}. Compound K₁₀[H₂V₁₆O₃₈]13H₂O (1) crystallizes in the monoclinic space group P2₁/c, a=12.12820(10), b=38.2302(3), c=12.35400(10) Å, =115.0470(10)°, V=5189.43(7) ų, D _c=2.624 gcm^–3. 10086 unique reflection and 702 refined parameters were used in structure refinement. R1=0.039, R2=0.109 (all data). From the same preparation the new compound K₁₁[V₁₈O₄₂(SO₄)]20H₂O (2) was also isolated and crystallographically characterized. Compound 2 crystallizes in the monoclinic space group P2₁/n, a=12.7854(3), b=20.2812(5), c=13.2386(4) Å, =115.3400(10)°, V=3102.53(14) ų, D _c=2.650 gcm^–3. 7115 unique reflections and 462 refined parameters were used in structure refinement. R1=0.046, R2=0.121 (all data).     

Thermal Decomposition Mechanism, Thermodynamical and Quantum Chemical of Properties [Pb(NTO)2⋅(H2O)]

The single crystal of lead salt of 3-nitro-1,2,4-triazol-5-one (NTO), [Pb(NTO)₂(H₂O)] was prepared and its structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, its space group is P2₁/n with crystal parameters of a=0.7262(1) nm, b=1.2129(2) nm, c=1.2268(3) nm, =90.38(2)°, V=1.0806(2) nm³, Z=4, D_c=2.97 g cm^–3, µ=157.83cm^–1, F(000)=888. The final R is 0.027. By using SCF-PM3-MO method we obtained optimized geometry for [Pb(NTO)₂H₂O] and particularly positions for hydrogen atoms. Through the analyses of MO levels and bond orders it is found that Pb atom bond to ligands mainly with its 6p_z and 6p_y AOs. The thermal decomposition experiments are elucidated when [Pb(NTO)₂H₂O] is heated, ligand water is dissociated first and NO₂ group has priority of leaving. Based on the thermal analysis, the thermal decomposition mechanism of [Pb(NTO)₂H₂O] has been derived. The lattice enthalpy and its lattice energy were also estimated.This revised version was published online in November 2005 with corrections to the Cover Date.