Syntheses and structural characterization of rhenium-bis-hydrazinopyrimidine core complexes with thiolate and Schiff base coligands

The reaction of perrhenate with 2-hydrazinopyrimidine in MeOH–HCl yields [ReCl₃(η¹-NNC₄H₃N₂H)(η²-HNNC₄H₃N₂)] (1). The analogous reaction with Na₂MoO₄ yields [MoCl₃(η¹-NNC₄H₃N₂H)(η²-HNNHC₄H₃N₂)] (1a). The reaction of 1 with pyrimidine-2-thiol and triethylamine produces [Re(η¹-C₄H₃N₂S)(η²-C₄H₃N₂S)(η¹-NNC₄H₃N₂)(η²-HNNC₄H₃N₂)] (2), while reaction of 1 with the Schiff base HSC₆H₄N=C(H)C₆H₄OH provides [Re(η³-SC₆H₄N=C(H)C₆H₄O)(η¹-NNC₄H₃N₂)(η²-HNNC₄H₃N₂)]·0.6CH₂Cl₂ (3·0.6CH₂Cl₂). The analogous hydrazinopyridine complex of the Schiff base, [Re(η³-SC₆H₄N=C(H)C₆H₄O)(η¹-NNC₅H₄N)(η²-HNNC₅H₄N)] (4), was also synthesized by reacting [ReCl₃(η¹-NNC₅H₄NH)(η²-HNNC₅H₄N)] with HSC₆H₄N=C(H)C₆H₄OH. The crystal structures of 1–4 have been determined.     

Lightinduced sulfur-dealkylation of phosphino-thioether nickel(0) complexes

The observation of homolytic S---CH₃ bond cleavage in (Ph₂P(o-C₆H₄)SCH₃)₂Ni⁰ under photochemical conditions has prompted further investigation of nickel(0) complexes and their stability. Tetradentate P₂S′₂ donor ligands (S′ = thioether type S donor) with aromatic rings incorporated into the P to S links, Ph₂P(o-C₆H₄)S(CH₂)₃S(o-C₆H₄)PPh₂ (arom-PSSP), or the S to S links, Ph₂P(CH₂)₂SCH₂(o-C₆H₄)CH₂S(CH₂)₂PPh₂ (PS-xy-SP), have been used to form four-coordinate, square planar nickel(II) complexes, [(arom-PSSP)Ni](BF₄)₂ (2) and [(PS-xy-SP)Ni](BF₄)₂ (3). The bidentate and tetradentate ligands, Ph₂P(o-C₆H₄)SCH₂CH₃ (arom-PSEt) and Ph₂P(CH₂)₂S(CH₂)₃S(CH₂)₂PPh₂ (PSSP), give similar complexes, [(arom-PSEt)₂Ni](BF₄)₂ (1) and [(PSSP)Ni](BF₄)₂ (4), respectively. Cyclic voltammograms of the Ni¹¹ complexes in CH₃CN show two reversible redox events assigned to and . The one-electron reduction product produced by stoichiometric amounts of Cp₂Co can be characterized by EPR. At 100 K rhombic signals show hyperfine coupling to two phosphorus atoms. Complete bulk chemical reduction of complexes 1, 2, 3 and 4 with Na/Hg amalgam provided the corresponding nickel(0) complexes 1^R, 2^R, 3^R and 4^R which were isolated as red solutions or solids characterized by magnetic resonance properties and reaction products. Photolysis of these nickel(0) complexes leads to S-dealkylation to produce alkyl radicals and dithiolate nickel(II) complexes. Complex 3 crystallized in the monoclinic space group P_2t/c with a=20.740(5), B=9.879(3), C=17.801(4) åA, ß=92.59(2)°, V=3644(2) ų and Z=4; complex 4: P2₁/c with A=13.815(4), B=13.815(4), C=15.457(5) åA, V=3365.4(14) ų and Z=4.     

Synthesis of one dimensional tin selenides in supercritical amines

Three new crystalline tin selenide salts have been prepared from the reactions of [PPh₄]₂[Sn(Se₄₃] in supercritical solvents. The starting material pyrolyzes in supercritical acetonitrile to form [PPh₄]₄[Sn₆Se₂₁] (I), and it also reacts with SnSe in supercritical ammonia leading to a mixture of [PPh₄]₄[Sn₃Se₁₁]₂ (II). and [PPh₄]₂[Sn(Se₄)(Se₆)₂] (III). All three compounds have been characterized by single crystal X-ray diffraction. Crystallographic data: for I, C₉₆H₉₀P₄Se₂₁Sn₆, space group triclinic, P-1, A = 18.763(3), B = 24.600(4), C = 13.137(1) Å, = 102.63(1), β = 93.66(1), γ = 108.72(1)°, V = 5544(1) ų, Z = 2, R = 0.0350, R_W = 0.0317: for II, C₉₆H₈₀P₄Se₂₂Sn₆, space group monoclinic P2₁/c, A = 31.500(4), B = 16.572(3), C = 22.352(3) Å, β = 103.53(1)°, V = 11344(3) ų, Z = 4, R = 0.0771, R_W = 0.0664: for III, C₄₈H₄₀P₂Se₁₆Sn, space group monoclinic, C2/c, A = 25.381(2), B = 13.934(4), C = 19.465(3) Å, β = 121.587(8)°, V = 5867(2) ų, Z = 4, R = 0.0807, R_W = 0.0650. One of the compounds, [PPh₄]₂[Sn(Se₄(Se₆₂], is a molecular cluster while the other two complexes [PPh₄]₄[Sn₃Se₁₁]₂ and [PPh₄]₄[Sn₆Se₂₁], are one dimensional tin selenide chains. The structures of the two chains are related and consits of tetrahedral and distorted trigonal bipyramidal tin(IV) centers bridged by Se²⁻, Se₂²⁻ and Se₃²⁻ chains.     

Ionic iridium-gold and rhodium-gold perfluorobenzenethiolato binuclear complexes: syntheses and solution behavior

By reacting [(C₅Me₅)M(SR_F)₂] (forM = Ir, Rf = C₆F₅ (1a) or C₆F₄H-p (1b); for M = Rh, Rf = C₆F₅ (2a) or C₆F₄H-p (2a)) in toluene with Na[AuCl₄], ionic binuclear compounds with the general formula [(C₅Me₅)M(μ-SR_F)₂AuCl₂]Cl for M = Ir, R = C₆F₅ (3a) or C₆F₄H-p (3a); for M = Rh, R_F = C₆F₅ (4a) or C₆F₄H-p (4b) can be obtained, together with small amounts of [(C₅Me₅)₂Rh₂(μ-SR_F)(μ-Cl)₂]Cl (R_F = C₆F₅ (5a) or C₆F₄H-p (5b)) as by-products when 2a and 2b were used.     

Two new multi-cobalt-containing heteropolyoxotungstates

Two new multi-cobalt-containing polyoxotungstates K₄Na₆Co₂(H₂O)₁₂{Co(H₂O)₄[Co₂(H₂O)₁₀Co₄(H₂O)₂(B--SiW₉O₃₄)₂]₂} · 40H₂O (1) and K₁₀Na₂[Co₄(H₂O)₂(GeW₉O₃₄)₂] · 20H₂O (2) have been obtained by the routine synthetic reactions in aqueous solution. The polyoxoanion framework of 1 consists of two sandwich-type polyoxoanions [Co₄(H₂O)₂(B--SiW₉O₃₄)₂]¹²⁻ connected together by a [CoO₂(H₂O)₄] cluster to constitute the sandwich dimer, and then, four isolated Co(H₂O)₅ cations coordinate to the dimer through four μ₂-O atoms. The polyoxoanion 2 is isomorphic to the sandwich-type polyoxoanion [Co₄(H₂O)₂(B--SiW₉O₃₄)₂]¹²⁻ in 1. The magnetic property of compound 1 has been studied by measuring its magnetic susceptibility in the temperature range 2.0–300.0 K, indicating the existence of intramolecular ferromagnetic Co–Co interactions, and, the electrochemical properties of 1 and 2 are detected in the pH 4 buffer solution.     

不同盐碱类型胁迫对红地球/贝达葡萄植株离子分布的影响

以盆栽红地球/贝达葡萄为试材,定量浇灌NaCl、Na₂SO₄、NaHCO₃、NH₄Cl和(NH₄)₂SO₄,筛选导致葡萄叶片黄化的盐、碱离子,研究不同盐碱类型胁迫对葡萄植株离子分布的影响.结果表明： NaHCO₃对植株影响最大,叶片在处理14 d时出现黄化症状,而NaCl和NH₄Cl处理28 d时出现黄化症状.NaHCO₃和NaCl处理均显著增加了植株各器官中Na^+含量,NaHCO₃处理根中Na⁺含量是对照的 6.4倍;这两种盐处理均降低了除叶片外其他器官中的K⁺含量,NaHCO₃处理显著降低了各器官中K/Na,根中K/Na仅为0.1,NaCl处理降低了除茎外其他器官中K/Na;这两种盐处理还降低了Ca²⁺、Mg²⁺、Fe²⁺向地上部的运输.NH₄Cl、(NH₄)₂SO₄和Na₂SO₄处理降低了植株各器官中K/Na,以NH₄Cl处理显著.碱性盐NaHCO₃对葡萄叶片黄化影响最大,其次是中性盐NaCl,再次是NH₄Cl,而(NH₄)₂SO₄和Na₂SO₄影响较小.     

福建闽南地区汉族与畲族的指长比

本文旨在研究福建闽南地区汉族和畲族指长比(R)的特点。随机选择福建闽南地区汉族506例（男性173例,女性333例）,畲族450例（男性231例,女性219例）,采用体质测量法,测量并计算左右侧6项指长比（R_2/3、R_2/4、R_2/5、R_3/4、R_3/5、R_4/5）。福建闽南地区汉族和畲族左、右侧指长比均呈R_2/3<R_2/4<R_3/4<R_2/5<R_4/5<R_3/5的趋势;汉族女性指长比左侧R_2/3、R_2/4、R_2/5、R_3/4、R_3/5和右侧R_2/3、R_2/4、R_2/5高于汉族男性（P<0.05）;畲族女性指长比左侧的R_2/3、R_2/4、R_2/5和右侧R_2/3、R_2/4高于畲族男性（P<0.05）;畲族男性指长比左、右侧R_2/3、R_2/4、R_2/5、R_3/5、R_4/5高于汉族男性（P<0.05）;畲族女性指长比左侧R_2/3、R_2/4和右侧R_2/3、R_2/4、R_2/5、R_4/5高于汉族女性（P<0.05）。同民族不同性别两侧R_2/4百分比分布差异有统计学意义,不同民族同性别右侧R_2/4百分比分布差异有统计学意义。福建闽南地区汉族和畲族指长比存在性别、侧别的不同,与其他地区、族群也存在差异。     

Titanium-carbon functionalities on an oxo surface defined by a calix [4] arene moiety and its redox chemistry

Lithiation of [p-Bu^t-calix[4]-(OMe)₂(OH)₂] (1), followed by reaction with TiCl₃(thf)₃ or TiCl₄(thf)₂, led to the corresponding titanium-calix[4]arene complexes [p-Bu^t-calix[4]-(OMe)₂(O)₂]TiCl] (2) and [p-Bu^t-calix[4]-(OMe)₂(O)₂]TiCl₂] (3), respectively. Reaction of 1 with TiCl₄(thf)₂ results in demethylation of the calix[4]arene and the obtention of [p-Bu^t-calix[4]-(OMe)₂(O)₃]TiCl] (4), whose hydrolysis led to [p-Bu^t-calix[4]-(OMe)(OH)₃] (6). The preparation of 6 can be carried out as a one-pot synthesis. Both 2 and 4 undergo alkylation reactions using conventional procedures, thus forming surprisingly stable organometallic species, namely [p-Bu^t-calix[4]-(OMe)₂(O)₂Ti(R)] (R = Me (7); CH₂Ph (8), p-MeC₆H₄ (9) and [p-Bu^t-calix[4]-(OMe)(O)₃Ti(R)] (R = Me (10); CH₂Ph (11); p-MeC₆H₄ (12)). Complexes 7 and 9 undergo a thermal oxidative conversion into 10 and 12, occurring with the demethylation of one of the methoxy groups. A solid state structural property of 9 and 12 has been revealed by X-ray analysis showing a self-assembly of the monomeric units into a columnar polymer, where the p-tolyl substituent at the metal functions as a guest group for an adjacent titanium-calixarene. Reductive alkylation of 3 with Mg(CH₂Ph)₂ gave 8 instead of forming the corresponding dialkyl derivative. Two synthetic routes have been devised for the synthesis of the Ti(III)-Ti(III) dimer [p-Bu^t-calix[4]-(OMe)(O)₃Ti]₂] (13): the reduction of 4 and the reaction of TiCl₃(thf)₃ with the lithiated form of 6. A very strong antiferromagnetic coupling is responsible for the peculiar magnetic behavior of 13. The proposed structures have been supported by the X-ray analyses of 4, 9, 12 and 13.     

An unexpected ‘4+2’ [N3S]/[NS] rhenium(IV) complex formed upon cleavage of a Re(V) imido bond

The reaction of [Re(NMe)Cl₃(PPh₃)₂] with the pentadentate [N₃S₂] ligand pyN₂H₂S₂---H₂ [2,6-bis(2-mercaptophenylamino)dimethylpyridine] (1) in the presence of triethylamine did not yield the anticipated six-coordinate complex [Re(NMe)(η⁵-pyN₂HS₂)] (2), but rather resulted in cleavage of the Re(V)=NMe bond. A novel six-coordinate Re(IV) [N₃S]/[NS] complex [Re(η⁴-SC₆H₄---2-NCH₂---C₅H₃N---C=NC₆H₄---2-S)(η²-NHC₆H₄---2-S)] (4) was thus obtained with the simultaneous coordination of 2-aminothiophenol, a dianionic bidentate [NS] donor resulting from the decomposition of the parent ligand and ligand 3, a dianionic tetradentate [N₃S] donor formed by partial self-condensation and subsequent oxidation of the parent ligand 1. Crystal data for 4: C₂₅H₁₈N₄S₃Re·CH₂Cl₂, monoclinic, space group P2₁/n, a=9.255(2) Å, b=11.181(2) Å, c=25.316(4) Å, β=97.434(3)°, V=2587.8(7) Å³ and Z=4.     

Low energy vibronic transitions of some tetrahalogenocobalt(II) complexes

Near-infrared absorption spectra of A₂CoX₄ (A = Cs, ethyl₄N; X = Cl, Br) single crystals and from KBr pellets at low temperature are recorded by the Fourier transform technique. At 2 K a rich fine structure of v₁(⁴A₂→⁴T₂) and v₂(⁴A₂→⁴T₁) ligand field spectra is detected which can be assigned to low symmetry level splittings due to actual site symmetries superimposed by vibrational fine structure. Comparison of fundamental frequencies obtained from far-infrared spectra allows an assignment of all peaks measured in the vibronic spectra to vibrational modes of the MX₄ complex. Zero-phonon bands are identified using the assistance of angular overlap calculations.     

Structural configuration of hexamethylphosphoramide complexes of uranium tetrahalides by magnetic susceptibility

Magnetic susceptibilities of UX₄hmpa₂ (where X = Cl⁻, Br⁻ and I⁻; hmpa = hexamethylphosphoramide) were measured from the b.p. of liquid helium to room temperature. The temperature dependence of the magnetic susceptibilities indicates that UI₄hmpa₂ has a trans-configuration, as have UCl₄hmpa₂ and UBr₄hmpa₂. Analysis of the magnetic susceptibilities on the basis of the ligand-field theory shows the distortion of the ligand field around the central uranium ion from O_h symmetry in the following order: UCl₄hmpa₂ < UBr₄hmpa₂ < UI₄hmpa₂.     

On the reduction behaviour of 2-methoxyethyl and 2-methylthioethyl substituted zirconocene dichlorides: crystal structure of (η,σ-C5Me4CH2CH2S)2Zr

A reduction of previously reported 2-methoxyethyl and 2-methylthioethyl functionalized zirconocenedichlorides (η⁵-C₅Me₄CH₂CH₂EMe)(η⁵-C₅Me₅)(ZrCl₂ (E = O, S) and (η⁵-C₅Me₄CH₂CH₂EMe)(η⁵-C₅Me₄CH₂CH₂E′Me)ZrCl₂ (E = O, S; E′ = O, S) with Mg/Hg in THF leads unexpectedly to the products of O---Me and S---Me bond cleavage (η⁵,σ-C₅Me₄CH₂CH₂E)(η⁵-C₅Me₅)ZrMe (E = O, S), (η⁵,σ-C₅Me₄CH₂CH₂E)(η⁵-C₅Me₄CH₂CH₂E′Me)ZrMe (E = O, S; E′ = O), and (η⁵,σ-C₅Me₄CH₂CH₂S)₂Zr respectively. The crystal structure of (η⁵,σ-C₅Me₄CH₂CH₂S)₂Zr was established by X-ray analysis. At that same time the reduction of (ηsu5-C_{5Me4CH2CH2EMe)(η⁵-C5Me5)ZrCl2 (E> = O, S)} under 1 atm of CO gives either only the dicarbonyl derivative (η⁵-C₅Me₄CH₂CH₂EMe) (η⁵-C₆Me₅)Zr(CO)₂ (E = O) or a complex mixture of products (E = S).     

Chele- and anticheleselectivity IV. Reaction-accelerating neighboring-group effects in the cross-coupling of vinylbromides with alkyl-transition metal reagents

The cross-coupling of vinylbromides with Me₄FeLi₂ or Me₄MnLi₂ is distinctly accelerated if the vinylbromide is provided with an hydroxy group in the -, β- or γ-position to the bromine atom (compounds 2–4). This was elucidated by intermolecular competition experiments and is very probably due to chelate formation as the first reaction step. Corresponding neighboring-group effects as seen in the reaction with 2–4 were observed by treating 2 with Bu₄MnLi₂, the -methoxy vinylbromide (5) with Me₄MnLi₂, the secondary amino vinylbromide (6) with Me₄FeLi₂, the tertiary amino vinylbromide (7) with Me₄FeLi₂ or Me₄MnLi₂, and the β-cyano vinylbromide (8) with Me₄FeLi₂. These effects allow very chemoselective cross-coupling. The observed cross-coupling with vinyl- bromides are believed to occur by oxidative addition (intramolecular due to preceding chelate formation) with subsequent reductive elimination.     

Reactivity of cationic carbonyl/phosphine ruthenium(II) compounds

Cis(or trans)-[RuCl₂(CO)₂(PPh₃)₂] react with two and one equivalents of AgBF₄ to give the recently reported [Ru(CO)₂(PPh₃)₂][BF₄]₂·CH₂Cl₂ (1) and novel [RuCl(CO)₂(PPh₃)₂][BF₄] · 1/2 CH₂Cl₂ (2), respectively. Cis-[RuCl₂(CO)₂(PPh₃)₂] also reacts with two equivalents of AgBF₄ in the presence of CO to give [Ru(CO)₃(PPh₃)₂][BF₄]₂ (3). Reactions of 1 and 2 with NaOMe and CO at 1 atm produce the carbomethoxy species [Ru(COOMe)₂(CO)₂(PPh₃)₂] (4) and [RuCl(COOMe)(CO)₂(PPh₃)₂] (5), respectively. Complex 4 can also be formed from the reaction of 3 with NaOMe and CO. Alternatively, 4 is formed from cis-[RuCl₂(CO)₂(PPh₃)₂] with NaOMe and CO at elevated pressure (10 atm); if these reactants are refluxed under 1 atm of CO, [Ru(CO)₃(PPh₃)₂] is the product. The reaction of [RuCl(CO)₃(PPh₃)₂][AlCl₄] with NaOMe provides an alternative route to the preparation of 5, but the product is contaminated with [RuCl₂(CO)₂(PPh₃)₂]. Compounds 1. 2, 4 and 5 have been characterised by IR, ¹H NMR and analysis, whilst the formulation of 3 is proposed from spectroscopic data only. This account also examines the reactivity of [Ru(CO)₂(PPh₃)₂][BF₄]₂ · CH₂Cl₂ with NaBH₄, conc. HCl, KI and, finally, MeCOONa in the presence of CO. The products of these reactions, namely cis-[RuH₂(CO)₂(PPh₃)₂], cis-[RuCl₂(CO)₂(PPh₃)₂], cis-[RuI₂(CO)₂(PPh₃)₂] and [Ru(OOCMe)₂(CO)₂(PPh₃)₂], have been identified by comparison of their spectra with previous literature.     

Molecular structure and reactions of azobenzene complexes with iron-lithium compounds

Reactions of azobenzene have been studied with heteronuclear iron-lithium compounds formed in the reaction of FeCl₃ with LiPh, one of the dinitrogen reducing systems of the Vol'pin type: Ph₄FeLi₄(OEt₂)₄ (1) and (H₂)FePh₄Li₄(OEt₂)₄ (2). The structures of the azobenzene complexes formed, (N₂Ph₂)₃FeLi₃(OEt₂)₃ (3) and (N₂Ph₂)₃FeLi₂(THF)₂ (4), as well as an ether-containing analog of the latter, (N₂Ph₂)₃FeLi₂(OEt₂)₂ (5), were determined by X-ray analysis of single crystals. Coordination of azobenzene at FeLi₃ and FeLi₂ clusters was shown to result in a sigificant elongation of the NN bond; partial cleavage of this bond on protolysis of the complexes resulted in the formation of hydrazobenzene and aniline. Magnetic susceptibility measurements and theoretic analysis of a similar model complex leads to the conclusion that the iron oxidation state in 3 may be considered between iron (I) and iron(III) (close to iron(I)), whereas in 4 and 5 it is close to iron(II).     

Studies of the oxovanadium(IV)—oxalate system: syntheses and crystal structures of binuclear (Ph4P)2[(VO)2(H2O)2(C2O4)3]·4H2O and of the one-dimensional chain material, (Ph4P)[VOCl(C2O4)]

The hydrothermal reactions of (Ph₄P)[VO₂Cl₂] and H₂C₂O₄ at 150 and 125°C yield (Ph₄P)₂[V₂O₂(H₂O)₂(C₂O₄)₃]·4H₂O (1) and (Ph₄P)[VOCl(C₂O₄)] (2), respectively. The structure of the molecular anion of 1 consists of a binuclear unit of oxovanadium(IV) octahedra bridged by a bisbidentate oxalate group. The VO₆ coordination geometry at each vanadium site is defined by a terminal oxo group, an aquo ligand, and four oxygen donors — two from the bisbidentate bridging oxalate and two from the terminal bidentate oxalate. The structure of 2 consists of discrete Ph₄P⁺ cations occupying regions between [VOCl(C₂O₄)]⁻_∞ spiral chains. The structure of the one-dimensional anionic chain exhibits V(IV) octahedra bridged by bisbidentate oxalate groups. Crystal data: 1·4H₂O, monoclinic P2₁/n, A = 12.694(3), B = 12.531(3), C = 17.17(3) Å, β = 106.32(2)°, V = 2621.3(13) ų, Z = 2, D_calc = 1.501 g cm⁻³, structure solution and refinement converged at a conventional residual of 0.0518; 2, tetragonal P4₃, A = 12.145(2), C = 15.991(3) Å, V = 2358.7(12) ų, Z = 4, R = 0.0452.     

小兴安岭酸性泥炭土硝化作用的类型及其驱动因子

以小兴安岭酸性森林泥炭土为研究对象,通过加入10 mL·L^-1乙炔及不同浓度的外源硫酸铵(0、1.2、6.0 mmol N·kg^-1)进行硝化培养试验,探究酸性泥炭土中硝化作用类型及主要驱动因子.结果表明:无论有无外加氮源,酸性泥炭土均存在较强的矿化作用(0.9～1.4 mg N·kg^-1·d^-1),经过2周的培养均发生了硝化作用(0.4～0.6 mg N·kg^-1·d^-1),且不同浓度硫酸铵处理之间无显著差异;而乙炔处理虽有较强的矿化作用(0.8 mg N·kg^-1·d^-1),但未发生明显的硝化作用(0 mg N·kg^-1·d^-1),说明该酸性泥炭土以自养硝化为主,外源无机氮源浓度对硝化作用无显著影响,硝化底物NH₃的主要来源不是外源硫酸铵,更可能来源于土壤中有机氮的矿化.培养0～14 d,无论有无外加氮源,酸性泥炭土氨氧化细菌(AOB)和古菌(AOA)丰度均显著增加,但不同浓度硫酸铵处理间无显著差异,表明外源无机氮浓度对氨氧化微生物的生长无显著促进作用.与不加乙炔的对照相比,乙炔处理AOB和AOA丰度随时间均无显著变化,推测AOA与AOB在该酸性泥炭土的硝化过程中都可能起一定的作用.     

广州地区晚稻田 CH4和N2O 的排放通量及其影响因素

用密闭箱法同时研究了广州地区晚稻田CH₄和N₂O的排放通量。结果表明,连续淹水、常规连作和水旱轮作等3种处理的CH₄平均排放通量分别为1.763、2.84和0.36mg·m^-2·h^-1,而N₂O的平均排放通量分别为6.74、11.69和55.07μgN₂O-N·m^-2·h^-1,表明稻田连续淹水显著增加CH₄的排放而降低N₂O的排放。水旱轮作降低CH₄排放而提高N₂O的排放,说明稻田CH₄和N₂O排放之间存在着消长关系。讨论了这2种温室气体排放的影响因素,并初步分析了它们对温室效应的相对贡献。     

Nitrogen, sulfur and oxygen donor adducts with copper(II) complexes of antitumor 2-formylpyridinethiosemicarbazone analogs: Physicochemical and cytotoxic studies

The preparation of N-, S- and O-donor ligand adducts with CuX⁺(HX=6-methyl-2-formylpyridinethiosemicarbazone (6HL); 2-formylpyridine-2^′-methylthiosemicarbazone (2′L); 2-formylpyridine-4′-methylthiosemicarbazone (4′HL)) is described. The N-donors, 2,2′-bipyridyl (bipy), 4-dimethylaminopyridine (dmap) give the complexes [Cu(6L)(bipy)]PF₆, [Cu(6L)(bipy)]Cl·5H₂O, [Cu(4′L)(bipy)]PF₆, [Cu(6L)(dmap)₂]PF₆·2.5 H₂O and [Cu(4′L)(dmap)₂]PF₆·H₂O which have been characterized by physical and spectroscopic techniques. Pentafluorothiophenolate (pftp) gives S-donor complexes [CuX(pftp)] (X=6L and 4′L) and thiolato co-ordination is proposed on the basis of spectroscopic evidence. Paratritylphenolate (ptp) and HPO²⁻₄ give O-donor complexes [Cu(6L)(ptp)], [Cu(4′L)(ptp)], [{Cu(6L)}₂HPO₄]·4H₂O, and [{Cu(4^′L)}₂HPO₄]·5H₂O which have been characterized by physical and spectroscopic techniques, as have the precursor complexes [Cu(6L)(CH₃COO)]·H₂O, [Cu(4′L)(CH₃COO)], Cu(6HL)(CF₃COO)](CF₃COO)·0.5H₂O, [Cu(4′HL)(CF₃COO)](CF₃COO), [Cu(2′L)Cl₂] and [Cu(2′L)(NO₃)₂]. Protonation constants for the ligands and some of their complexes have been determined. 2-Formylpyridinethiosemicarbazone (HL) complexes of silver, gold, zinc, mercury, cadmium and lead are also discussed. Cytotoxicity against the human tumor cell line HCT-8 and antiviral data for selected compounds are presented.     

不同冬季覆盖作物对稻田甲烷和氧化亚氮排放的影响

采用静态箱-气相色谱法对不同冬季覆盖作物处理［免耕直播黑麦草-双季稻(T₁)、免耕直播紫云英 双季稻(T₂)、翻耕移栽油菜-双季稻(T₃)、免耕直播油菜-双季稻(T₄)和冬闲-双季稻(CK)］下稻田甲烷（CH₄）和氧化亚氮（N₂O）排放进行观测,分析了不同冬季覆盖作物对稻田CH₄和N₂O排放的影响.结果表明：在冬季作物生长期,不同冬季覆盖作物稻田CH₄和N₂O总排放量与对照（CK）的差异均达到极显著水平（P<0.01）;T₃和T₁处理的稻田CH₄和N₂O排放量最高,其CH₄排放量分别为0.88 和0.60g·m^-2,N₂O排放量分别为0.23 和0.20 g·m^-2;冬季作物还田后,各处理早、晚稻田CH4排放量均明显高于对照.早稻田CH₄排放量最高的为T₁和T₂处理,分别达21.70和20.75 g·m^-2;晚稻田CH₄排放量最高的为T₃和T₄处理,分别为58.90和54.51 g·m^-2.各处理早、晚稻田N₂O总排放量均显著高于对照,T₁、T₂、T₃和T₄处理的早稻田N₂O总排放量分别比对照增加53.7%、12.2%、46.3%和29.3%,晚稻田分别比对照增加28.6%、3.8%、34.3%和27.6%.