REACTION OF α-CHLOROTOLUENE WITH ELEMENTAL SULFUR IN LIQUID AMMONIA

Abstract

α-Chlorotoluene (1) reacts with elemental sulfur in liquid ammonia affording dibenzyl disulfide (2), dibenzyl trisulfide (3), dibenzyl tetrasulfide (4), dibenzyl pentasulfide (5) and benzylidene benzylimide (6) at a low temperature such as 20°C. This reaction is presumed to be initiated by the nucleophilic attack of ammonium thioaminohydroxylate, “H₂NS^-NH₄ ⁺,” or dithioaminohydroxylate, “H₂NSS^-NH₄,” formed upon treating elemental sulfur in liquid ammonia, on α-chlorotoluene (1). Benzylidene benzylimide (6) is presumed to be formed from benzylamine, which can be formed by treatment of α-chlorotoluene (1) with ammonia.     

The structure of monomeric unsolvated and weakly solvated (Me<Subscript>2</Subscript>Cu)Li and (Me<Subscript>2</Subscript>Cu)Cu

Density functional theory was used to study the structure of various isomers of (Me₂Cu)Li (1), (Me₂Cu)Cu (2), (Me₂Cu)Li · 2Me₂O (3), and (Me₂Cu)Cu · 2Me₂S (4) in the gas phase. Isomers of 1 and 3 were shown to be typical cuprates, whereas isomers of 2 and 4 should rather be treated as unsolvated and solvated methylcopper dimers, respectively. The reasons for the difference between structures 2, 4 and 1, 3 were considered. The energies of solvation of 1 by two dimethyl ether molecules (∼34 kcal/mol) and of 2 by two dimethyl sulfide molecules (∼36 kcal/mol) and the dissociation energies of all the compounds to the dimethylcuprate anion and the corresponding cation were calculated. The energies of solvation of 1 and 2 being almost equal, the transformation of 2 into 4 decreased the dissociation energy much more substantially than the transformation of 1 into 3.     

Synthesis and Some Reactions of the Metal Phosphorus Double-bonded Complexes C5R5 (CO)2Mo=P(NMe2)2

Abstract

The reaction of the metalhydrides C₅R₅(CO)₃Mo-H (R=H (la), Me (lb) with P(NMe₂)₃ leads to the metal-phosphorus double-bonded species 2a,b via the intermediate formation of C₅(CO)₂ (Me₂N)₃P)Mo-H, which can only be identified spec-troscopically in solution.     

Chalcone-derived thiosemicarbazones and their zinc(II) and gallium(III) complexes: spectral studies and antimicrobial activity

Chalcone-derived 3-phenyl-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCTPh) (1), 3-(4-chlorophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4ClPh) (2), 3-(4-bromophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4BrPh) (3), and 3-(4-nitrophenyl-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4NO₂Ph) (4) were obtained as well as their gallium(III) and zinc(II) complexes [Ga(PyCTPh)₂]NO₃ (Ga1), [Ga(PyCT4ClPh)₂]NO₃ (Ga2), [Ga(PyCT4BrPh)₂]NO₃ (Ga3), [Ga(PyCT4NO₂Ph)₂]NO₃ (Ga4), [Zn(PyCTPh)₂] (Zn1), [Zn(PyCT4ClPh)₂] (Zn2), [Zn(PyCT4BrPh)₂] (Zn3), and [Zn(PyCT4NO₂Ph)₂] (Zn4). The chalcones, thiosemicarbazones, and zinc(II) complexes were not active against Pseudomonas aeruginosa. The thiosemicarbazones proved to be more active than the parent chalcones against Staphylococcus aureus and Candida albicans. Coordination to zinc(II) resulted in activity improvement of most thiosemicarbazones against S. aureus. Coordination to gallium(III) significantly improved the antimicrobial activity of all thiosemicarbazones against the studied micro-organisms, suggesting this to be an effective strategy for antimicrobial activity enhancement.     

Heterometallic Alkoxides of Molybdenum and Heavy Transition Metals—the Synthesis and Prospects of Application

The alkoxides of molybdenum and other heavy transition elements such as Ta or Nb were found to be unreactive towards each other. The bimetallic derivatives could be obtained either via partial hydrolysis that gave Mo₂Ta₄O₈(OMe)₁₆ (I) or via partial thermolysis that provided access to Mo₄Ta₂O₈(OⁱPr)₁₄ (II), Mo₃Ta₂O₈(OⁱPr)₁₀ (III), Mo₄Ta₄O₁₆(OⁱPr)₁₂ (IV), Mo₄Nb₂O₈(OⁱPr)₁₄ (V) and Mo₄W_2–x Mo _x O₁₀(OⁱPr)₁₂ (VI). I–VI can be isolated only from hydrocarbon media as the presence of alcohols leads to precipitation of insoluble homometallic derivatives of molybdenum. The cathodic reduction of MoO(OR)₄ (R = Me, Et) in the presence of LiCl and M(OR)₅ (M = Nb, Ta) leads only to formation of LiMo₂O₂(OMe)₇(MeOH) (VII) or LiMo₂O₂(OEt)₇ (VIII) respectively.     

Synthesis,characterization, and reactivity studies in ethylene polymerization of cyclometalated palladium(II) complexes containing terdentate ligands with N,C,N-donors

The reaction of [Na₂PdCl₄] with 3,5-bis(2-pyridoxy)toluene (L_pyH) in acetic acid yields the cyclometalated complex [PdCl(L_py-N, C, N)] (1). Complex 1 can be further converted into neutral species by metathesis reaction exchange of chloride by either iodide or thiocyanate to yield [PdX(L_py-N, C, N)] (X = I (2), SCN (3)). The chloride can be replaced by neutral ligands like pyridine or acetonitrile in the presence of silver tetrafluoroborate to give the corresponding cationic compounds [PdL(L_py-N, C, N)]BF₄ (L = Py (4), MeCN (5)). In contrast, the reaction of [Na₂PdCl₄] with 3,5-bis(3, 5-dimethylpyrazol-1-ylmethyl)toluene (L_pzH) under analogous conditions yields the neutral complex [PdCl₂(L_pzH-N, N)](6) with the ligand bidentate N,N-donor. The cyclometalated palladium complex [PdCl(L_pz-N, C, N)] (7) was prepared by the reaction of Pd(OAc)₂ with L_pzH in acetic acid followed by a metathetic reaction with lithium chloride in acetone/water. Complexes 1, 6, and 7 in the presence of methylaluminoxane (MAO) lead to an active catalyst for the polymerization of ethylene.     

PLATINUM(II) COMPLEXES OF P(III) CYCLOPHOSPHAMIDE DERIVATIVES

Abstract

The syntheses of the P(III) analogues of cyclophosphamide, isophosphamide and triphosphamide are reported. These compounds (4–6, respectively) polymerize easily at room temperature but are sufficiently stable in solution to react with Cl₂Pt(NCPh)₂, forming cis-Cl₂Pt(4)₂, cis-Cl₂Pt(5)₂ and cis-Cl₂Pt(6)₂ (complexes 9–11, respectively). Complex 10 can also be made by condensing cis-Cl₂Pt[ClPN(CH₂CH₂Cl)CH₂CH₂CHO]₂ with ClCH₂CH₂NH₂, while an alternate route to 9 and 11 is afforded by the condensation of cis-Cl₂Pt[Cl₂PN(CH₂CH₂Cl)₂]₂ with H₂NCH₂CH₂CH₂OH and ClCH₂CH₂NHCH₂CH₂CH₂OH, respectively. Complexes 9–11 exist in two diastereomeric configurations and these can be separated in the cases of 9 and 11 by column chromatography. ³¹P NMR spectral data for the complexes are discussed and the results of NCl antitumor screening are presented.     

Hexafluoropropylene Oxide–Alcohol: A Convenient System for Silica Dissolution

Abstract

A new method of silica dissolution is described. It involves the formation of a stable SiF₄ · n ROH complex (1, 1a) just from SiO₂ and anhydrous alcoholic HF generated in situ from commercially available hexafluoropropene oxide. Alcoholic SiF₄ complexes can be easily converted to different organosilicon compounds of the type SiF₄L₂ and (LH)₂SiF₆ [L = 1,10-phenantroline (2a), 2,2′-dipyridyl (2b), Me₂SO (2c), pyridine (2d), triethanolamine (3a)]. Different silica-containing compounds can be used in this strategy—silicagel, sand, alumosilicates, and even rice husk.

GRAPHICAL ABSTRACT     

Synthesis,structure and methyl methacrylate polymerization of cobalt(II), zinc(II) and cadmium(II) complexes with N,N′,N-bidentate versus N,N′,N-tridentate N,N′,N-bis((1H-pyrazol-1-yl)methyl)amines

Mononuclear Co(II), Zn(II) and Cd(II) complexes derived from bidentate or tridentate N,N′,N-bis((1H-pyrazol-1-yl)methyl)amines (L_n = L_A, L_B), where L_A is N,N-bis((1H-pyrazol-1-yl)methyl)-3-methoxypropan-1-amine and L_B is 3-methoxy-N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)propan-1-amine, have been synthesized and characterized. The geometry at Co(II) and Cd(II) for [L_ACoCl₂], [L_BCoCl₂] and [L_BCdBr₂] with N,N′,N-tridentate ligands (L_n = L_A, L_B) can be described as a distorted trigonal bipyramid achieved by coordinative interaction of N_pyrazole, two halides and the nitrogen of amine moiety. However, the molecular structure of four-coordinate [L_AZnCl₂] can be best described as tetrahedral, resulting in an eight-membered chelate ring. [L_ACoCl₂] polymerized methyl methacrylate in the presence of modified methylaluminoxane at 60 °C and resulted in poly(methylmethacrylate) (PMMA) with higher molecular weight and narrower polydispersity index compared to the other synthesized complexes. However, all the synthesized complexes yielded syndiospecific PMMA, characterized using ¹H NMR spectroscopy, with ca. 0.70.     

Organoselenido Complexes of Tungsten

Organometallic tungsten selenido complexes of the type [cpW(CO)₃]₂Se_m; m = 2 (1), 3 (2), 4 (3), can be easily synthesized via insertion of selenium into the alkali-metal tungsten bond of LiWcp(CO)₃ in appropriate ratios and subsequent oxidation of the produced W-selenolates with O₂/SiO₂. In contrast, reactions of K₂Se₆ with [cpW(CO)₃Cl] and 18-crown-6 in DMF lead to a mixture óf [cpW(CO)₃]₂Se₄ (3), the η¹ Se-bonded selenocarbamato complex [cpW(CO)₃SeC(O)NMe₂] (4) and the ionic complex [(18-crown-6)K]⁺[cpW(Se₄)₂]^? (5). The crystal structures of 3 and 4 together with their ⁷⁷Se NMR data are presented.     

Über 4-Alkylamino-bzw. 4-Arylamino-5,6-dihydro-2(1H)-pyridinthione

Heating 1-alkyl- or 1-aryldihydro-6-methyl-2(1H)-pyrimidinethiones5, 6 in an inert medium causes rearrangement to 4-alkylamino-(4-arylamino-)-5,6-dihydro-2(1H)-pyridinethiones11, 12, probably via the methylene form29, by thermal heterolysis of the N₁/C₂ bond and exchange of the alkylamino (arylamino) group 1 through the carbon atom of the methylene group 6. The aminodihydropyridinethiones11, which can be regarded as cyclic derivatives of 3-aminothiocrotonamide, react with bistrichlorophenylmalonate under diacylation, and with formaldehyde and primary amines to yield aminodialkylation products of the enamine system, tetrahydro-4-hydroxy-7,7-dimethyl-5-thioxopyrido[4,3-b]pyridine-2(1H)-ones13, 14 and hexahydro-7,7-dimethylpyrido[4,3-d]pyrimidine-5(6H)-thiones18, 19, 21 respectively. H₂O₂ converts11 to the corresponding 4-aminodihydro-2(1H)-pyridones22, which can be reconverted into11 with P₄S₁₀.11 reacts with alkyl halides to 2-alkylthiodihydropyridines23, 24, 25. The mechanism of the methylpyrimidine-pyridine rearrangement is discussed.     

Syntheses,structural characteristics,and antimicrobial activities of new organotin(IV) 3-(4-bromophenyl)-2-ethylacrylates

New organotin(IV) carboxylates, [n-Bu₂SnL₂] (1), [Et₂SnL₂] (2), [Me₂SnL₂] (3), [n-Oct₂SnL₂] (4), [n-Bu₃SnL] _n (5), [Me₃SnL] _n (6), and [Ph₃SnL] _n (7), where L?=?3-(4-bromophenyl)-2-ethylacrylate, were synthesized and characterized by elemental analysis, FT-IR, and multinuclear NMR (¹H, ¹³C, and ¹¹⁹Sn). Spectroscopic studies confirm coordination of L to the organotin moiety via COO group. Single-crystal X-ray analysis reveals bridging mode of coordination in 6. Packing diagram established a supramolecular cage-like structure for 6 due to Sn–O interactions (3.287?Å). Subsequent antimicrobial activities proved them to be active biologically.     

Synthesis and structures of silicon-, germanium-, and tin-containing imido-alkyl molybdenum complexes (ArN)2Mo(CH2EMe3)2 (E = Si, Ge, Sn)

New silicon-, germanium-, and tin-containing imido-alkyl molybdenum complexes (ArN)₂Mo(CH₂EMe₃)₂ (Ar is 2,6-diisopropylphenyl; E = Si (1), Ge (2), Sn (3)) were prepared in the crystalline state in 58–66% yields by the reactions of the (ArN)₂MoCl₂(DME) complex with alkyllithium derivatives Me₃ECH₂Li (E = Si or Ge) or the Grignard reagents Me₃ECH₂MgCl (E = Ge or Sn). The structures of complexes 1–3 and the known analog (ArN)₂Mo(CH₂Bu^t)₂ (4) were established by X-ray diffraction analysis. Complexes 1–3 were found to be isostructural. The coordination environment about the Mo atom can be described as a distorted tetrahedron. Complex 4 has a similar structure. The Mo-C distance tends to decrease with increasing electron donating ability of the EMe₃ group.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 597–600, March, 2005.     

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.     

Crystal structures and fluorescence properties of two architecture-correlated Zn(II)/Cd(II) MOFs constructed from an unprecedented tri-triazole ligand

By employing an unprecedented tri-triazole ligand, 4-amino-3,5-bis-(1H-1,2,4-triazole)-1,2,4-triazole (H₂L), two Zn(II)/Cd(II) metal-organic frameworks (MOFs), [ZnL]·3H₂O (1) and [CdL]·H₂O (2), were successfully synthesized and characterized. In the two complexes, M(II) centers are chelated and bridged by L bridges to form a one-dimensional (1-D) 4₁ helical chain in 1 with high-symmetry Pbca, and a 2₁ helical chain in 2 with lower symmetry P2₁/n, respectively. The two chains are further linked by L into two structure-correlated three-dimensional (3-D) architectures. PXRD and TG analysis confirmed the phase purity and stability of 1 and 2. The solid-state fluorescence properties of the prepared MOF revealed a maximum emission at 382?nm and 393?nm (λ_ex = 330?nm), ascribing to the intra-ligand transitions. Interestingly, an additional strong emission peak at 516?nm can be observed in 1 (below 400?°C), while the emission was silenced in 2. The additional emission band may be attributed to the subtle difference of architectural features and coordination configurations between in 1 and 2.     

Radical–molecule reaction CH<Subscript>2</Subscript>Cl + NO<Subscript>2</Subscript>: a mechanistic study

The radical–molecule reaction mechanism of CH₂Cl with NO₂ has been explored theoretically at the B3LYP/6–311G(d,p) and MC–QCISD (single-point) levels of theory. Our results indicate that the title reaction proceeds mostly through singlet pathways, less go through triplet pathways. The initial association between CH₂Cl and NO₂ is found to be the carbon-to-nitrogen attack forming the adduct a H₂ClCNO₂ with no barrier, followed by isomerization to b ₁ H₂ClCONO-trans which can easily convert to b ₂ H₂ClCONO-cis. Subsequently, the most feasible pathway is the C–Cl and O–N bonds cleavage along with the N–Cl bond formation of b (b ₁ , b ₂ ) leading to product P ₁ CH₂O + ClNO, which can further dissociate to give P ₅ CH₂O + Cl + NO. The second competitive pathway is the 1,3-H-shift associated with O–N bond rupture of b ₁ to form P ₂ CHClO + HNO. Because the intermediates and transition states involved in the above two favorable channels all lie below the reactants, the CH₂Cl+NO₂ reaction is expected to be rapid, as is confirmed by experiment. The present results can lead us to understand deeply the mechanism of the title reaction and may be helpful for further experimental investigation of the reaction.     

Synthesis,urease inhibitory activities,and molecular docking studies of two Cu(II) complexes

Two mononuclear copper(II) complexes, [Cu(C₄H₃N₂O₂)₂?·?4H₂O] (1) and [Cu(C₁₂H₁₁N₂O₂Cl₂)₂] (2), were synthesized and structurally characterized by single-crystal X-ray analysis. The copper(II) adopts a square-planar environment in 1, while the geometry in 2 can be described as distorted square-pyramidal. Complexes 1 and 2 were evaluated for their inhibitory activities against jack bean urease in vitro and both were found to have strong inhibitory activities comparable to that of acetohydroxamic acid. A docking simulation was performed to position 2 into the jack bean urease active site to determine the probable binding conformation.     

Copper(II) complexes with pyridine-2,6-dicarboxylic acid from the oxidation of copper(I) iodide

Via an oxidation reaction of Cu(I) iodide with pyridine-2,6-dicarboxylic acid (H₂L) in DMF three copper(II) complexes, [(CH₃)₂NH₂]₂[CuL₂] (1), K₂[CuL₂]?H₂L?H₂O (2) and [Cu(L)(H₂O)]_n (3), were synthesized and characterized. The structures of 1–3 were determined by single crystal X-ray diffraction studies. In-situ DMF decomposition produces dimethylamine base under solvothermal conditions and a proton transfer reaction takes place for the complex formation of 1. 3-D networks are stabilized in 1 and 2 via hydrogen bonds. Complex 3 is a 1-D coordination polymer with Cu-O semi-coordination bonds. Thermal decomposition of the complexes results in the corresponding metal oxides. Also, the electrochemical behavior of 1 was determined to be a metal-centered and diffusion-controlled, one-electron reduction process.     

über 4-Alkylamino-bzw. 4-Arylamino-5,6-dihydro-2(1H)-pyridinthione

Heating 1-alkyl- or 1-aryldihydro-6-methyl-2(1H)-pyrimidinethiones5, 6 in an inert medium causes rearrangement to 4-alkylamino-(4-arylamino-)-5,6-dihydro-2(1H)-pyridinethiones11, 12, probably via the methylene form29, by thermal heterolysis of the N₁/C₂ bond and exchange of the alkylamino (arylamino) group 1 through the carbon atom of the methylene group 6. The aminodihydropyridinethiones11, which can be regarded as cyclic derivatives of 3-aminothiocrotonamide, react with bistrichlorophenylmalonate under diacylation, and with formaldehyde and primary amines to yield aminodialkylation products of the enamine system, tetrahydro-4-hydroxy-7,7-dimethyl-5-thioxopyrido[4,3-b]pyridine-2(1H)-ones13, 14 and hexahydro-7,7-dimethylpyrido[4,3-d]pyrimidine-5(6H)-thiones18, 19, 21 respectively. H₂O₂ converts11 to the corresponding 4-aminodihydro-2(1H)-pyridones22, which can be reconverted into11 with P₄S₁₀.11 reacts with alkyl halides to 2-alkylthiodihydropyridines23, 24, 25. The mechanism of the methylpyrimidine-pyridine rearrangement is discussed.     

Two W/Mo complexes containing 2,3-dihydroxynaphthalene: synthesis and structure analysis

Two W/Mo complexes, [Et₃NH]₂[WO₂(C₁₀H₆O₂)₂] (1) and [Et₃NH]₂[MoO₂(C₁₀H₆O₂)₂] (2), were synthesized by the reaction of Na₂WO₄?·?2H₂O and (NH₄)₂Mo₂O₇?·?4H₂O with 2,3-DHN (DHN?=?dihydroxynaphthalene) and triethylamine, and characterized by X-ray diffraction and IR. The two complexes exhibit chiral octahedral geometry at central metals, although the overall structure is racemic. Single crystals of 1 are more difficult to obtain than for 2. The molybdenum complex can be easily isolated at room temperature (around 25°C), while the tungsten one needs to be isolated under 15°C, otherwise, the quality of crystal will be poor, leading to disorder. The structures of these two complexes are chiral and enantiomorphous to each other.