Synthesis, Structure, and 31P NMR of Sulfur/Oxygen-Bridged Incomplete Cubane-Type Molybdenum and Tungsten Clusters with Triphenylphosphine Ligands

Sulfur/oxygen-bridged incomplete cubane-type triphenylphosphine molybdenum and tungsten-clusters [Mo₃S₄Cl₄(H₂O)₂(PPh₃)₃]·3THF (1A), [Mo₃S₄Cl₄(H₂O)₂(PPh₃)₃]·2THF (2A), [Mo₃OS₃Cl₄(H₂O)₂(PPh₃)₃]·2THF (1B), and [W₃S₄Cl₄(H₂O)₂(PPh₃)₃]·2THF (1C) were prepared from the corresponding aqua clusters and PPh₃ in THF/MeOH. On recrystallization from THF, procedures with and without addition of hexane to the solution gave 1A and 2A, respectively, while the procedures gave no effect on the formation of 1B and 1C. Crystallographic results obtained are as follows: 1A: monoclinic, P2₁/n, a=17.141(4) Å, b=22.579(5) Å, c=19.069(4) Å, =96.18(2)°, V=7337(3) ų, Z=4, R(R _w)=0.078(0.102); 1C: monoclinic, P2 ₁/c, a=12.635(1) Å, b=20.216(4) Å, c=27.815(3) Å, =96.16(1)°, V=7062(2) ų, Z=4, R(R _w)=0.071(0.083). If the phenyl groups are ignored, the molecule [Mo₃S₄Cl₄(H₂O)₂(PPh₃)₃] in 2A has idealized CS symmetry with the mirror plane perpendicular to the plane determined by the metal atoms, while the molecule in 1A does not have the symmetry. The tungsten compound 1C is isomorphous with the molybdenum compound 2A. ³¹P NMR spectra of 1A, 2A, and 1C were obtained and compared with similar clusters with dmpe (1,2-bis(dimethylphosphino)ethane) ligands.     

g-C3N4/CaTi2O5复合材料制备及其光催化性能

利用类石墨氮化碳（g-C₃N₄）和亚稳相钙钛氧化物（CaTi₂O₅）固相法制备C₃N₄/CaTi₂O₅复合材料。利用X射线衍射（XRD）、金相显微镜、扫描电子显微镜（SEM）及附带能谱分析仪（EDS）和N₂吸附-脱附对样品的显微结构和比表面积进行检测分析,并用紫外-可见吸收光度计（UV-Vis）测试了样品的光吸收性能,研究C₃N₄与CaTi₂O₅物质的量之比（n_C3N4/nCaTi₂O₅）对C₃N₄/CaTi₂O₅复合样品的物相结构和微观形貌的影响,同时考察C₃N₄/CaTi₂O₅复合样品在可见光照射下光催化降解罗丹明染料效果。实验结果表明：相比纯C₃N₄和CaTi₂O₅样品,C₃N₄/CaTi₂O₅复合样品在可见光下具有较高的光催化性能,随着n_C3N4/nCaTi₂O₅增加,样品的光催化降解率随之增加而后降低,当n_C3N4/nCaTi₂O₅=1：1时,样品的光催化降解率达到最大值99.5%,并且循环重复利用5次后,样品的光催化剂降解率仍几乎保持不变。复合样品光催化性能提高主要归因于复合能级结构有效地抑制了电子和空穴复合所致。     

Preparation and study of hydrides of fullerenes C60 and C70

Fullerene hydrides were prepared by hydrogenation of fullerences C₆₀ and C₇₀ using proton transfer from 9,10-dihydroanthracene to fullerene and were studied by mass spectrometry (electron impact, field desorption), IR, UV, and¹H and¹³C NMR spectroscopy. The main product of the hydrogenation of C₆₀ is C₆₀H₃₆, which is sufficiently stable. Hydrogenation of fullerene C₇₀ gives a series of polyhydrides C₇₀H _n (n=36–46), and the main product is C₇₀H₃₆. The dehydrogenation of C₆₀H₃₆ by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone is not quantitative and results in the formation of fullerene derivatives along with C₆₀. The comparison of the IR and¹H and¹³C NMR spectral data for solid C₆₀H₃₆ with the theoretical calculations suggests that the fullerene hydride has aT-symmetric structure and contains four isolated benzenoid rings located at tetrahedral positions on the surface of the closed skeleton of the molecule. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 4, pp. 671–678, April, 1997.     

Molecular complexes of C60 with tetrasulfur tetranitride

Compounds C₆₀(S₄N₄)_2−x (C₆H₆) _x (1a-d) withx=0.67 (a), 1.0 (b), 1.1 (c), and 1.2 (d), in which isomorphous replacement of S₄N₄ with benzene takes place, were obtained by the reaction of fullerence C₆₀ with tetrasulfur tetranitride in benzene. Complexes C₆₀·S₄N₄ (2) and C₆₀(S₄N₄)₂ (3) containing no solvent were isolated from toluene. The compositions of the compounds were established by elemental and thermogravimetric analyses. The data of IR and X-ray photoelectron (XP) spectroscopies show that in the complexes studied the transfer of electron density occurs mainly from the nitrogen atoms of S₄N₄. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 37–40. January 1977.     

Cadmium(II) complexes with phosphine tellurides: synthesis and multinuclear (31P, 125Te,and 113Cd) NMR characterization in solution

New cadmium(II) complexes with phosphine telluride ligands of the type CdX₂(R₃PTe)_n [X?=?ClO₄^?, n?=?4: R?=?n-Bu (1), Me₂?N (2), C₅H₁₀?N (3), C₄H₈?N (4) or OC₄H₈?N (5); X?=?Cl^–, n?=?2: R?=?n-Bu (6), Me₂?N (7), C₅H₁₀?N (8), C₄H₈?N (9) or OC₄H₈?N (10)] have been synthesized and characterized by elemental analyses, IR and multinuclear (³¹P, ¹²⁵Te, and ¹¹³Cd) NMR spectroscopy. In particular, the solution structures of these complexes were confirmed by ¹¹³Cd NMR at low temperature, which displays a quintuplet for each of the perchlorate complexes and a triplet for each of the chloride complexes due to coupling with four and two equivalent phosphorus atoms, respectively, indicating a four-coordinate tetrahedral geometry for the metal center. These multiplet features were further accompanied by one bond Te–Cd couplings, clearly showing that the ligand is coordinated to the metal through tellurium. The results are discussed and compared with those obtained for closely related phosphine chalcogenide analogs.     

New complexes of fullerences C60 and C70 with CoII and MnII tetraphenylporphyrinates and their ESR study

Complexes of fullerenes C₆₀ and C₇₀ with cobalt(II) and manganese(II) tetraphenylporphyrinates of compositions Mn(TPP)·(C₆₀)₂(CS₂)_1.5 (1), Mn(TPP)·C₇₀(CS₂) _x , wherex<=1.25 (2), Co(TPP)·C₆₀(CS₂)_0.5 (3), and Co(TPP)·C₇₀(CS₂) _x , wherex<0.25 (4), were synthesized and studied by ESR spectroscopy. At 77 K, complexes1 and2 have singlet ESR spectra characteristic of the low-spin (S=1/2) state of Mn^II, withg=2.002 and linewidths of 250 G and 300 G, respectively, and differing significantly from that of the initial Mn^II(TPP) (g ₁=5.9 andg=2.0,S=5/2). The spectra of complexes1 and2 exposed to oxygen exhibit hyperfine structure due to interaction with⁵⁵Mn and¹⁴N nuclei. The ESR spectra of complexes3 and4 are asymmetric (<g>=2.4, ΔH _pp=(500–600) G), which is due to the overlap of parallel and perpendicular spectral components. The absence of ESR signals from C₆₀ ^.− and C₇₀ ^.− radical anions makes it possible to conclude that the formation of complexes1–4 is not accompanied by electron transfer from Co(TPP) and Mn(TPP) to fullerences C₆₀ and C₇₀. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 722–725, April, 1999.     

Reactions ofo-tosylaminobenzaldehyde withp-aminobenzenesulfonamides. Synthesis and structures of 13-(4-aminosulfonylphenyl)-6,12-epimino-5,11-ditosyl-5,6,11,12-tetrahydrodibenzo[b,f]-1,5-diazocine and itsN-substituted derivatives

The reactions ofo-tosylaminobenzaldehyde (1) withp-aminobenzenesulfonamides (2a-c) yielded 13-(p-RNHSO₂C₆H₄)-6,12-epimino-5,11-ditosyl-5,6,11,12-tetrahydrodibenzo[b f]-1,5-diazocines (3a-c) (R=H (a); 2-thiazolyl (b); or 2,6-dimethoxy-4-pyrimidinyl 2,6-dimethoxy-4-pyrimidinyl (c). The structure of compound3c was confirmed by X-ray diffurction study. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2035–2039, November, 1997.     

LIGAND EXCHANGE AND LIGAND COUPLING VIA THE σ-SULFURANE INTERMEDIATE IN THE REACTION OF ALKYL 2-PYRIDYL SULFOXIDE WITH GRIGNARD REAGENTS: CONVENIENT PREPARATION OF 2,2′-BIPYRIDINES

Abstract

The reaction between methyl 2-pyridyl sulfoxide (1) with Grignard reagents afforded 2,2′-bipyridine (2) in moderate yield. The reaction is considered to involve initial ligand exchange to generate 2-pyridylmagnesium halide which in the subsequent step attacks the original sulfoxide to form the σ-sulfurane that undergoes ligand coupling to afford 2. The reaction of t-butyl 2-pyridyl sulfoxide (3) with C₆H₅MgBr, however, gave only 2-phenylpyridine (4). This may be due to steric hindrance to the initial ligand exchange. Formation of 2 is a convenient process for preparation of 2,2′-bipyridines bearing various substituents.     

Reactions of GeMe2-bridged dicyclopentadienes with molybdenum carbonyl: formation of germylidyne trimolybdenum clusters

In thermal reactions of the doubly bridged dicyclopentadienes (C₅H₃R(SiMe₂))(C₅H₃R(GeMe₂)) (R=H (1), ^tBu (5)) with Mo(CO)₆, the bridging GeMe₂ is cleaved to give the corresponding degermylated products [(η⁵-C₅H₃R)₂(SiMe₂)]Mo₂(CO)₆ (3, rac-7), or both GeMe₂ and SiMe₂ are cleaved to afford the nonbridged products [(η⁵-C₅H₄R)Mo(CO)₃]₂ (2, 6). The reactions also produce germylidyne trimolybdenum clusters [(η⁵-C₅H₃R)₂(SiMe₂)](η⁵-C₅H₄R)[Mo(CO)₂]₃(μ₃-GeMe) (4, rac-/meso-7) containing the Mo₃(μ₃-GeMe) units. Similarly, reaction of the single GeMe₂-bridged dicyclopentadienes (C₅H₅)₂GeMe₂ (9) with Mo(CO)₆ also results in the degermylated 2, as well as the similar trimolybdenum cluster [(η⁵-C₅H₅)Mo(CO)₂]₃(μ₃-GeMe) (10). The molecular structures of 4 and trans-5 were determined by X-ray diffraction.     

g-C_3N_4/CaTi_2O_5复合材料制备及其光催化性能

利用类石墨氮化碳(g-C_3N_4)和亚稳相钙钛氧化物(CaTi_2O_5)固相法制备C_3N_4/CaTi_2O_5复合材料。利用X射线衍射(XRD)、金相显微镜、扫描电子显微镜(SEM)及附带能谱分析仪(EDS)和N2吸附-脱附对样品的显微结构和比表面积进行检测分析,并用紫外-可见吸收光度计(UV-Vis)测试了样品的光吸收性能,研究C_3N_4与CaTi_2O_5物质的量之比(nC_3N_4/nCaTi_2O_5)对C_3N_4/CaTi_2O_5复合样品的物相结构和微观形貌的影响,同时考察C_3N_4/CaTi_2O_5复合样品在可见光照射下光催化降解罗丹明染料效果。实验结果表明:相比纯C_3N_4和CaTi_2O_5样品,C_3N_4/CaTi_2O_5复合样品在可见光下具有较高的光催化性能,随着nC_3N_4/nCaTi_2O_5增加,样品的光催化降解率随之增加而后降低,当nC_3N_4/nCaTi_2O_5=1∶1时,样品的光催化降解率达到最大值99.5%,并且循环重复利用5次后,样品的光催化剂降解率仍几乎保持不变。复合样品光催化性能提高主要归因于复合能级结构有效地抑制了电子和空穴复合所致。     

Cycloaddition of C60 fullerene to stable 2-RSO2-benzonitrile oxides

The interaction of stable 2-RSO₂-benzonitrile oxides1a−c (R=Ph, Bu^t, or PhMeN) with C₆₀ fullerene proceeds at the double (6,6)-bond of fullerene as the [3+2] cycloaddition to form the corresponding isoxazolines2a−c. The molecular structure of compound2b was established by X-ray structural analysis. The interaction of C₆₀ fullerene with 2-(5-methyl-4-nitrothiophene)carbonitrile sulfide, which was obtained by thermolysis of 5-(5′-methyl-4′-nitro-2′-thienyl)1,3,4-oxathiazol-2-one, affords only unstable products. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 118–126, January, 1997.     

Heteroatom Effects on Singlet–Triplet Energy Gaps of Divalent Five-Membered Ring X2C2H2C (X = N,P, As,and Sb)

Thermal energy gaps, ΔE_s–t; enthalpy gaps, ΔH_s–t; and Gibbs free energy gaps, ΔG_s–t between the singlet (s) and triplet (t) states of X₂C₂H₂C, 1_X (X = CH, N, P, As, and Sb) were calculated and compared with those analogues, XC₂H₃C, 1′_X (X = N, P, As, and Sb) at the B3LYP/6-311++G** level of theory. Density functional theory (DFT) calculations indicated that the ΔG_s-t, for 1_X (X = N and P) should be lower with respect to their monosubstituted 1′_X . In contrast, the ΔG_s-t for 1_X (X = As and Sb) should be larger with respect to 1′_X . The ΔG_s-t for 1_X and 1′_X were increased in the following order: 1_Sb > 1_As > 1_C > 1_P > 1_N ; 1′_Sb > 1′_As > 1′_P > 1_C > 1′_N , respectively.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

A Protocol for the Synthesis of C8-16 Alkyl 2,3-Isopropylidene-α-L-Rhamnosides

Dodecyl 2,3-isopropylidene-α-L-rhamnoside (1) is a key building block in the synthesis of bioactive natural oligorhamnosides, cleistetrosides 1–8, and cleistriosides 1–6. Currently, all of the methods for preparing 1 have drawbacks, including the use of highly moisture-sensitive Lewis acids or expensive transition-metal catalysts and the need for multiple protection/deprotection steps. In order to address these practical difficulties, herein we describe an efficient synthesis of C_8-16 alkyl 2,3-isopropylidene-α-L-rhamnosides 1–9 via Fischer type of glycosylation reaction between unprotected, unactivated L-rhamnose and C_8-16 fatty alcohols in the presence of TfOH-SiO₂.     

Komplexe des zweiwertigen Molybdäns,Derivate des Oktahalodimolybdat(II)-Ions, 4. Mitt.: Darstellungen und Kristallstrukturen von zwei neutralen Komplexen mit 4-Methylpyridin

Mo₂Cl₄ Pic ₄·CHCl₃ (A) (Pic=4-methylpyridine) and Mo₂Br₄ Pic ₄ (B) crystallize in the monoclinic space group.A inC2/c (No. 15) witha=15.175 (4),b=10.847 (2),c=19.946 (6) and =104.52 (2)°;D _o=1.71 (2),D _c =1.72 gcm^–3 forZ=4.B inP2_l/n (No. 14) witha=9.270 (3),b=16.614 (5),c=9.305 (3) and =91.96 (5)°;D _o=2.03 (3),D _c =2.05 gcm^–3 forZ=2.Two halogens and 4-methylpyridines of the MoX ₂ Pic ₂ group are in the trans position. Mo–Mo bond lengths are 2.153 96) forA and 2.150 92) forB. Both molecules are situated on the inversion center resulting in the eclipsed configuration of the ligands around the molybdenum pair. The structure ofB has been refined to the conventionalR factors of 0.08 and 0.098. Disorder on the part of 4-methylpyridines and chloroform molecules stopped the refinement ofA at the endR value of 0.175.Mean Mo–X and Mo–N bonding distances are 2.40 (2), 2.25 (5) forA and 2.53 (3), 2.25 (1) forB.

     

Supramolecular dyad derived from a buckybowl series of O2N2-donor naphthodiaza-crowns coordinated to C60: photophysical,NMR and theoretical studies

Supramolecular complexation of C₆₀ with L¹-L⁵ were studied in toluene, chloroform and 1,2-dichlorobenzene solvents using UV–vis, fluorescence, ¹H, ¹³C NMR spectroscopy as well as density functional theory (DFT) calculations. The Job’s plot of continuous variation method established 1:1 stoichiometry for L¹-L⁵/C₆₀. Binding constants (K) calculated for L¹-L⁵/C₆₀ were also determined employing UV–vis and fluorescence spectroscopy. Both steady-state and time-resolved fluorescence spectroscopic surveys showed remarkable fluorescence quenching phenomenon for L¹-L⁵ in the presence of C₆₀ which was primarily attributed to involvement of a static process. The observed fluorescence quenching in L¹–L⁵ was described in terms of both π–π and n–π interactions of the naphthalene moieties and the nitrogen donor groups on the aza-crown macrocyclic ligands with C₆₀, respectively. Moreover, DFT calculations using B₃LYP/6-31G* basis set confirmed on the aforesaid π–π interaction of naphthalene groups on the aza-crowns with C₆₀. The DFT calculations also established significant distributions of charge between C₆₀ and L¹-L⁵ in according to the electronic structure and geometry of L¹-L⁵/C₆₀, very similar to phthalocycnine/C₆₀ systems.     

Improved Synthesis of C 2‐Symmetric 4,4′‐α,ω‐Alkylenedioxy‐bis(3‐methoxybenzaldehydes)

Abstract

An improved Williamson synthesis of C ₂‐symmetric 4,4′‐(α,ω‐alkylenedioxy)‐bis(3‐methoxybenzaldehydes) from vanillin is described. These dialdehydes are often insoluble in cold acetone, which renders their purification especially facile.     

Selective reduction of fullerene C60 by metals in neutral and alkaline media. Interaction of C60 with KOH

The reduction of fullerene C₆₀ by Zn and Mg in DMF was studied both in the presence and absence of KOH. Fullerene C₆₀ was reduced in these systems to form the C₆₀ ^n– (n = 1, 2, and 3) anions. The anions were detected by optical and ESR spectroscopies. It was found that Mg reduced C₆₀ to the monoanion, Mg/KOH and Zn reduced C₆₀ to the dianion, and Zn/KOH reduced C₆₀ to the trianion. Like KCN, potassium hydroxide adds to fullerene upon interaction with C₆₀ in DMF. The reaction of C₆₀ with KOH in benzonitrile was accompanied by the generation of the fullerene monoanion. A possible mechanism of the formation of fullerene monoanions in the presence of KOH is discussed. The degradation of the C₆₀ ^n– anions in air was studied.     

Ti3C2Tx/MnO2正极在水系锌电池中的电化学性能

二氧化锰(MnO₂)材料具有比容量大、电极电位高、储量丰富以及价格低廉等优势,成为水系锌电池正极最受关注的一类材料,然而其仍然存在着结构稳定性差和电化学储存机理复杂的问题。因此,我们通过两步合成法制备了一种花苞状结构的MnO₂负载在Ti₃C₂T_x表面形成Ti₃C₂T_x/MnO₂复合材料,通过X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)对复合样品的结构、成分和形貌进行表征。通过将Ti₃C₂T_x/MnO₂复合材料作为正极,与锌负极匹配组装成水系锌电池,研究了其分别在2 mol·L^-1 ZnSO₄、2 mol·L^-1 ZnSO₄+0.1 mol·L^-1 MnSO₄、30 mol·L^-1三氟甲基磺酸四乙基铵(TEAOTf)+1 mol·L^-1三氟甲烷磺酸锌(ZnOTf)和3 mol·L^-1 ZnOTf四种电解液中的电化学性能。结果表明,Ti₃C₂T_x/MnO₂在2 mol·L^-1 ZnSO₄中的比容量较高,但循环稳定性很差。将TEAOTf盐和ZnOTf盐共溶于水中,设计了一种新型的含惰性阳离子的超高浓度盐包水电解液(30 mol·L^-1 TEAOTf+1 mol·L^-1 ZnOTf),不仅提高了Ti₃C₂T_x/MnO₂材料的可逆性,而且有效抑制了电极材料在循环过程中的溶解。     

Iron(III), nickel(II) and zinc(II) complexes based on acetophenone-S-methyl-thiosemicarbazone: synthesis,characterization, thermogravimetry,and a structural study

New complexes, [Fe(L)Cl], [Ni(L)], and [Zn(L)C₂H₅OH] (1–3), were synthesized by template reaction of 2-hydroxy-acetophenone-S-methyl-thiosemicarbazone with 2-hydroxy-benzaldehyde. The compounds were characterized by elemental analysis, magnetic measurements, FT-IR, ¹H NMR, UV–visible, and ESI–MS spectra. In these complexes, the ligand is coordinated to the metal ion as dinegatively charged tetradentate chelating agents via the N₂O₂ donor set. The iron(III) and zinc(II) complexes exhibit square pyramidal geometry whereas the nickel(II) complex has a square planar geometry. The crystal structure of 1, determined by X-ray diffraction method, indicates that 1 crystallizes in the monoclinic space group P21/c with Z = 4. Thermal decompositions of the compounds have been investigated using TGA in air.