Ratio In Toluene Research Articles

Hydridotris(3,5-dimethylpyrazolyl)borate Dimethylamido Imido Niobium and Tantalum Complexes: Synthesis, Reactivity, Fluxional Behavior, and C–H Activation of the NMe2 Function

The pseudo-octahedral dichlorido imido hydridotris(3,5-dimethylpyrazolyl)borate niobium and tantalum compounds [MTp*Cl2(NtBu)] (M = Nb (1a), Ta (1b); Tp* = BH(3,5-Me2C3HN2)3) were prepared in better yields by treatment of equimolar quantities of MCl3(NtBu)py2 and KTp* in toluene at reflux. Reactions of 1a,b with a small excess of LiNMe2 (1:1.2 ratio) in toluene gave the corresponding chlorido dimethylamido derivatives [MTp*Cl(NMe2)(NtBu)] (M = Nb (2), Ta (3)). Mixed methyl dimethylamido [MTp*Me(NMe2)(NtBu)] (M = Nb (4), Ta (5)) complexes were synthesized in good yields by heating for several days a mixture of 2 or 3 and MgClMe, in a 1:1 molar ratio. However, the reactions of 1a,b with excess LiNMe2 led to bis(dimethylamido) complexes [MTp*(NMe2)2(NtBu)] (M = Nb (6), Ta (7)) as unitary species. 4 and 5 reacted with B(C6F5)3 to give the cation-like complexes [MTp*(NMe2)(NtBu)]+[BMe(C6F5)3]− (M = Nb (8), Ta (9)), whereas in the case of complexes 6 and 7 the reaction led to [MTp*(NMe2){N(Me)═CH2-κ1N}(NtBu)]+[BH(C6F5)3]− (M = Nb (10), Ta (11)) derivatives as result of the C–Hmethyl bond activation into a NMe2 function. The restricted rotation process of the NMe2 moiety around the M–Namido bond in complexes 2–7, the pseudo-rotation process of the Tp* ligand into the cationic species 8 and 9, and the CH2 terminal group around the N═CH2 bond in compounds 10 and 11 were observed and studied by 1H DNMR spectroscopy. The isomerization of two enantiomers in the mixtures of 4 and 5 with B(C6F5)3 was detected, and their mechanism was proposed. All compounds were studied by IR and multinuclear NMR (1H, 13C, and 15N) spectroscopy, and the molecular structures of complexes 1a,b and 3 were determined by X-ray diffraction methods.

Chiral N,N,O-Scorpionate Zinc Alkyls as Effective and Stereoselective Initiators for the Living ROP of Lactides

The chiral and the enantiopure bis(pyrazol-1-yl)methane-based NNO-donor scorpionate ligands in the form of the alcohol compounds (bpzbeH) [bpzbe = 1,1-bis(3,5-dimethylpyrazol-1-yl)-3,3-dimethyl-2-butoxide], (bpzteH) [bpzte = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-para-tolylethoxide], and (R,R)-bpzmmH {(R,R)-bpzmm = (1R)-1-[(1R)-6,6-dimethylbicyclo[3.1.1]-2-hepten-2-yl]-2,2-bis(3,5-dimethylpyrazol-1-yl)ethoxide} have been utilized to obtain new NNO-scorpionate zinc alkyl complexes. The reaction of bpzbeH, bpzteH (racemic mixture), or (R,R)-bpzmmH (enantiopure) with [ZnMe2] in a 1:1 molar ratio in toluene afforded the mononuclear and monoalkyl zinc complexes [Zn(Me)(κ3-NNO)] (1–3), respectively. However, when the same reaction was carried out with [ZnEt2], [ZntBu2], or [Zn(CH2SiMe3)2], new dinuclear complexes of the type [Zn(R)(κ-NNμ-O)]2 (κ-NNμ-O = bpzbe, R = Et 4, tBu 5, CH2SiMe36; bpzte, R = Et 7, tBu 8, CH2SiMe39; (R,R)-bpzmm, R = Et 10, tBu 11, CH2SiMe312) were obtained. The single-crystal X-ray structure...

Experimental and Theoretical Investigations of Tellurium(IV) Methanediides and Their Insertion Products with Sulfur and Iodine

The reactions of Li2[C(Ph2PS)2] with tellurium tetrahalides in a 1:1 molar ratio in toluene afford the complexes {TeX2[C(Ph2PS)2]}2 (7a, X = Cl; 7b, X = Br; 7c, X = I). These complexes dimerize through halide bridges in the solid state, and the tridentate ligand is S,C,S-coordinated to the tellurium center with a Te–C bond length of 2.024(3), 2.030(6), and 2.045(8) Å, respectively. In the case of TeBr4, small amounts of the complex TeX2[SC(Ph2PS)2] (8b, X = Br) were isolated and shown by X-ray analysis to be the result of formal sulfur insertion into the Te–C bond of 7b. Complex 8b and the corresponding dichloride and diiodide, 8a (X = Cl) and 8c (X = I), may be prepared in good yields by the metathetical reactions of Li2[SC(Ph2PS)2] with TeX4 in toluene. The complex TeI2[(I2)C(Ph2PS)2] (9) was isolated as a minor product from the reaction of Li2[C(Ph2PS)2] and TeI4 and identified by X-ray crystallography. Complex 9 is constructed from the insertion of an iodine atom of an I2 molecule into the Te–C bond of 7c, resulting in a T-shaped geometry at that iodine atom and an almost linear Te–I–I unit with an elongated I–I bond; the C–I bond length is typical for a C(sp3)–I bond. DFT calculations supplemented with Hirshfeld charge analysis, Boys–Foster localization of molecular orbitals, and evaluation of the electron localization functions indicate that in these species the ligand engages predominantly in σ bonding through the lone pairs on the carbon and sulfur atoms. The latter atoms participate in three-center interactions with tellurium. The bonds between the heavy elements and carbon are strongly polarized, and the character of the latter atom ranges from sp2 to sp3.

Synthesis, characterization and reactivity of a zwitterionic amine bridged bis(phenolate) lanthanide complex

A zwitterionic amine bridged bis(phenolate) ytterbium(III) complex was synthesized, and its reactivity with a zinc cluster was explored. The reaction of (C 5H 5) 3Yb(THF) with the amine bridged bis(phenol) HONNOH [ONNO = Me 2NCH 2CH 2N{CH 2-(2-O-C 6H 2-Bu t 2-3,5)} 2] in a 1:2 M ratio in toluene at 80 °C produced the zwitterionic ytterbium complex [ONNO]Yb[ONNO(μ 4-H)] ( 1) in a high isolated yield. The reaction of ZnEt 2 with 1 equiv of PhCH 2OH gave a zinc cluster Zn 7Et 6(OCH 2Ph) 8 ( 2) in a good isolated yield. Complex 1 reacted with complex 2 in a 7:1 M ratio at room temperature to afford the unexpected ligand redistributed product [ONNO]Zn(THF) ( 3). These complexes were well characterized by elemental analyses, IR spectra and NMR spectroscopy in the case of complexes 2 and 3. The definitive molecular structures of complexes 2 and 3 were determined by single-crystal X-ray analyses.

S,C,S-Pnictogen bonding in pincer complexes of the methanediide [C(Ph2PS)2]2−

The metathetical reactions of Li(2)[C(Ph(2)PS)(2)] with MCl(3) (M = Sb, Bi) in a 1:1 molar ratio in toluene afford the complexes {MCl[C(Ph(2)PS)(2)]}(2), which dimerise through weak MS interactions; the S,C,S-coordination of the tridentate ligand to the metal in the monomeric units incorporates a polar M-C single bond and a three-centre two-electron S-M-S bond.

Synthesis and crystal structure of [Y(C 5Me 4SiMe 3){μ-O(CH 2) 3CH 3}{N(SiHMe 2) 2}] 2

A dimeric yttrium complex [Y(C 5Me 4SiMe 3){μ-O(CH 2) 3CH 3}{N(SiHMe 2) 2}] 2 ( 1) was isolated as one of the byproducts from the reaction of Y{N(SiHMe 2) 3} 3(THF) 2 with C 5Me 4HSiMe 3 in 1:1.1 molar ratio in toluene at 100 °C for 2 d. Complex 1 was characterized by elemental analysis, NMR spectroscopy, FT-IR spectroscopy, and X-ray single crystal structure analysis. X-ray diffractions revealed that complex 1 was a symmetric dimer, and the center metal Y 3+ was six-coordinated by one nitrogen atom from the amide group, two bridging oxygen atoms from the O(CH 2) 3CH 3 groups, and one cyclopentadienyl ring in η 5-fashion to adopt a distorted tetrahedron geometry. The formation of complex 1 was postulated to be a result from C-O bond cleavage reaction of THF.

Synthesis of indenyllanthanide amides: the effective initiators for polymerization of methyl methacrylate

Diisopropylamido bisindenyl lanthanides (C9H7)2LnN(i-Pr)2 (Ln=Gd(1), Y(2), Er (3)) were succesfully synthesized in satisfied yield by the reaction of Ln(N(i-Pr)2)3(THF) with indene in 1:2 molar ratio in toluene. AH of the complexes exhibit very high catalytic activity in the polymerization of methyl methacrylate. The resulting polymers have narrow molecular weight distributions and high syndiotacticity.

Synthesis and Structural Characterisation of a Hexanuclear TiIV Compound Ti6(μ2-O)2(μ3-O)2(μ2-OC4H9)2(OC4H9)6(OOCCHCl2)8

Titanium tetra-butoxide was reacted with dichloroacetic acid in 1 : 1 and 1 : 2 molar ratio in toluene at ambient temperature to give, respectively, the mono- and bis-substituted products Ti(OBun)3(OOCCHCl2) and Ti(OBun)2(OOCCHCl2)2 (1) in quantitative yields. However, when a toluene solution of compound 1 was kept at −20 ◦C for crystallisation, colourless crystals of a hexanuclear complex Ti6(μ2-O)2(μ3-O)2(μ2-OC4H9)2(OC4H9)6(OOCCHCl2)8 (2) were obtained. The basic skeletal arrangement of compound 2, as revealed by X-ray diffraction, can be described as corner-removed, inversion-related [Ti-O]4 cubes with face-linked oxide bridges.

Reactions of Cyclopalladated Complexes with Lithium Diphenylphosphide

Reactions of the cyclopalladated dimer {Pd(η2-L1)(μ-Cl)}2 (7) derived from N,N-dimethylbenzylamine (HL1) with lithium diphenylphosphide were studied under varied conditions. The LiPPh2 reagents used were purchased from Sigma-Aldrich Co. or synthesized from PPh3, ClPPh2, or HPPh2 by known general methods. Depending on the source of lithium phosphide, solvent, and reagent ratio, reactions of LiPPh2 with complex 7 resulted in the formation of different products. The commercial LiPPh2 solutions reacted with compound 7 and several other cyclopalladated dimeric complexes in THF to form the corresponding mononuclear derivatives with Ph2P(CH2)4OH as an auxiliary ligand, Pd(η2-L)Cl{PPh2(CH2)4OH}. The monophosphido-bridged analogue of dimer 7, {Pd(η2-L1)}2(μ-Cl)(μ-PPh2) (17), was the most common product of the 1:2 reactions of dimer 7 with other LiPPh2 solutions in THF. ortho-(Diphenylphosphino)-N,N-dimethylbenzylamine (20) was obtained in the reactions of complex 7 with the synthesized solutions of LiPPh2 using a 1:4.5 molar ratio of the reagents in THF or a 1:2 ratio in toluene. Possible mechanisms of these reactions are discussed.

Phosphine- and Carbene-Ligated Silver Acetate: Easily-Accessed Synthons for Reactions with Silylated Nucleophiles

The useful synthon tricyclohexylphosphinesilver(I) acetate is easily prepared on gram scale by the reaction of silver(I) acetate and tricyclohexylphosphine in a 1:1 ratio in toluene. (PCy(3))Ag(OAc) (1) reacts with a wide range of silylated nucleophiles (Me(3)Si-X; product with X = N(3), 2; Cl, 3; SCN, 4; 1,2,4-triazol-1-yl, 5; trifluoromethanesulfonate (OTf), 6; SPh, 8; Br, 9) to effect room temperature Ag-X bond formation at the expense of the Ag-OAc bond. All new products were characterized by multinuclear NMR spectroscopies, IR spectroscopy, microanalysis, and X-ray crystallography. X-ray crystallography indicated a variety of coordination geometries at silver(I) are accessible, as di- and tetranuclear complexes were observed in all cases except 1, which forms a three-coordinate, mononuclear complex. In the case of 8, NMR and mass spectrometric data suggest fluxional species of variable nuclearity (but with empirical formula [(PCy(3))Au(SPh)](n)) exist in solution. To provide more definitive evidence of Ag-S bond formation, the ligand 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) was used to synthesize a new starting material, (IPr)AgOAc (10), the Ag-OAc bond of which is amenable to silylation by Me(3)Si-X (complex with X = N(3), 11; Cl, 12; SPh, 14). Complex 14 was characterized crystallographically, and provided definitive evidence for Ag-S bond formation via silylation with PhS-SiMe(3). Me(3)SiBr and Me(3)SiI are also competent in the silylation of 10 to yield 13 and 15, but these compounds were more cleanly synthesized by the reaction of 12 and KBr/KI in a biphasic CH(2)Cl(2)/H(2)O mixture. In a preliminary exploration of reactivity, it was determined that azidosilver(I) complexes 2 and 11 react rapidly and quantitatively with (NO)(SbF(6)) (as was previously demonstrated in a related azidogold(I) system) to yield cationic silver(I) species (detected by mass spectrometry). In acetonitrile solution, ligand rearrangements of these cationic silver(I) species yield cationic bis(phosphine) or bis(carbene) complexes, the identities of which were authenticated by X-ray crystallography.

On the Search for NNO-Donor Enantiopure Scorpionate Ligands and Their Coordination to Group 4 Metals

The preparation of new chiral bis(pyrazol-1-yl)methane-based NNO-donor scorpionate ligands in the form of the lithium derivatives [Li(bpzb)(THF)] [1; bpzb = 1,1-bis(3,5-dimethylpyrazol-1-yl)-3,3-dimethyl-2-butoxide] and [Li(bpzte)(THF)] [2; bpzte = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-p-tolylethoxide] or the alcohol ligands (bpzbH) (3) and (bpzteH) (4) has been carried out by 1,2-addition reactions with trimethylacetaldehyde or p-tolualdehyde. The separation of a racemic mixture of the alcohol ligand 3 has been achieved and gave an enantiopure NNO alcohol-scorpionate ligand in three synthetic steps: (i) 1,2-addition of the appropriate lithium derivative to trimethylacetaldehyde, (ii) esterification and separation of diastereoisomers 5, (iii) saponification. Subsequently, the enantiopure scorpionate ligand (R,R)-bpzmmH {6; R,R-bpzmmH = (1R)-1-[(1R)-6,6-dimethylbicyclo[3.1.1]2-hepten-2-yl]-2,2-bis(3,5-dimethylpyrazol-1-yl)ethanol} was obtained with an excellent diastereomeric excess (>99% de) in a one-pot process utilizing the aldehyde (1R)-(-)-myrtenal as a chiral substrate to control the stereochemistry of the newly created asymmetric center. These new chiral heteroscorpionate ligands reacted with [MX(4)] (M = Ti, Zr; X = NMe(2), O(i)Pr, OEt, O(t)Bu) in a 1:1 molar ratio in toluene to give, after the appropriate workup, the complexes [MX(3)(kappa(3)-NNO)] (7-18). The reaction of Me(3)SiCl with [Ti(NMe(2))(3)(bpzb)] (7) or [Ti(NMe(2))(3)(R,R-bpzmm)] (11) in different molar ratios gave the halide-amide-containing complexes [TiCl(NMe(2))(2)(kappa(3)-NNO)] (19 and 20) and [TiCl(2)(NMe(2))(kappa(3)-NNO)] (21 and 22) and the halide complex [TiCl(3)(kappa(3)-NNO)] (23 and 24). The latter complexes can also be obtained by reaction of the lithium compound 1 with TiCl(4)(THF)(2) and deprotonation of the alcohol group of 6 with NaH, followed by reaction with TiCl(4)(THF)(2) in a 1:1 molar ratio, respectively. Isolation of only one of the three possible diastereoisomers of the complexes 19 and 22 revealed that chiral induction from the ligand to the titanium center took place. The structures of these complexes were elucidated by (1)H and (13)C{(1)H} NMR spectroscopy, and the X-ray crystal structures of 3-7, 12, and 24 were also established. Finally, we evaluated the influence that the chiral center of the new heteroscorpionate complexes has on the enantioselectivity of the asymmetric epoxidation of allylic alcohols.

Investigation of the preparation and physical properties of a novel semi-interpenetrating polymer network based on epoxised NR and PVA using maleic acid as the crosslinking agent

Natural rubber (NR) and its derivatives as renewable and biodegradable materials have attracted considerable attention because of the serious pollution problems caused by synthetic materials and a shortage of resources. A new semi-interpenetrating polymer network (semi-IPN) based on epoxidised natural rubber and polyvinyl alcohol containing maleic acid as a crosslinking reagent was synthesized and characterized by FTIR, XRD, SEM, swelling ratio in both distilled water and toluene, and mechanical properties. The curing time and dose of maleic acid were varied from 10 to 60 min, and from 10 to 60% (w/w), respectively. An IR spectroscopic study indicated the presence of an ester linkage at 1730 cm −1 in maleic acid crosslinked with PVA in semi-IPN films. In addition, the crystalline content of PVA dramatically decreased after adding maleic acid in the semi-IPN, as observed from its XRD. The semi-IPNs exhibit good mechanical properties, thermal stability, characteristics of a polyvinyl alcohol–maleic acid polymer network. An SEM of the semi-IPNs containing maleic acid showed no phase separation, when compared with the sample prepared in the absence of maleic acid.

Early transition metal derivatives stabilised by the phenylenediamido 1,2-C 6H 4(NCH 2tBu) 2 ligand: Synthesis, characterisation and reactivity studies: Crystal structures of [Ta{1,2-C 6H 4(NCH 2tBu) 2} 2Cl] and [Zr{(1,2-C 6H 4(NCH 2tBu) 2}(NMe 2)(μ-NMe 2)] 2

Li 2[1,2-C 6H 4(NCH 2 tBu) 2] reacts with one equiv of [TiCl 4(THF) 2] in refluxing toluene to give the chelate compound [Ti{1,2-C 6H 4(NCH 2 tBu) 2}Cl 2(THF)] ( 1), isolated as a black product, while the reaction of the dilithio diamido salt with one equiv of [ZrCl 4(THF) 2] in refluxing toluene affords the dinuclear zirconium derivative [Zr{1,2-C 6H 4(NCH 2 tBu) 2}Cl(THF)(μ-Cl)] 2 ( 2), obtained as an orange solid. Treatment of the dilithio diamido salt with TaCl 5 in a 2:1 molar ratio in toluene yields [Ta{1,2-C 6H 4(NCH 2 tBu) 2} 2Cl] ( 3) as a red product. The reaction of 1,2-C 6H 4(NHCH 2 tBu) 2 with [Zr(NMe 2) 4] in toluene at room temperature affords the dinuclear zirconium complex [Zr{1,2-C 6H 4(NCH 2 tBu) 2}(NMe 2)(μ-NMe 2)] 2 ( 4). The dibenzyl derivative [Ti{1,2-C 6H 4(NCH 2 tBu) 2}(CH 2Ph) 2] ( 5) is obtained by the reaction of 1 with 2 equiv of Mg(CH 2Ph)Cl at −78 °C. Compound 1 reacts with the lithium amide reagent LiN(SiMe 3) 2 to afford [Ti{1,2-C 6H 4(NCH 2 tBu) 2}Cl{N(SiMe 3)}] ( 6). The μ-oxo titanium derivative [(Ti{1,2-C 6H 4(NCH 2 tBu) 2}{CH 2Ph}) 2(μ-O)] 7 is precipitated when compound 5 is maintained in solution. The tendency of these compounds to coordinate donor ligands and their reactivity with Lewis acid reagents are described. All compounds were analytically and spectroscopically characterised and the molecular structures of the diamine 1,2-C 6H 4(NHCH 2 tBu) 2 and the complexes 3 and 4 were established by single-crystal X-ray diffraction studies. The lack of correlation between the degree of metallacycle folding and phenylene ring distortion is observed in the solid state structures. The performance of precursors 1, 3 and 5 were evaluated in ethylene polymerisation upon activation with B(C 6F 5) 3, methylaluminoxane (MAO) and sMAO as cocatalysts, with very modest activities.

Synthesis and Structural Characterisation of a Hexanuclear GdIII Compound Gd6(μ3-OH)6(acac)12·1.25 CHCl3 as a Potential Precursor for Gd2O3 Nanomaterials

While aging the reaction mixture of gadolinium tri-isopropoxide with acetylacetone (pentane-2,4- dione, acacH) in a 1 : 2 molar ratio in toluene for crystalisation, crystals of Gd6(μ3-OH)6(acac)12・1.25 CHCl3 (1) were obtained in high yield. The crystal structure analysis reveals that 1 has a M6O12 core which is constituted of two distorted, tricapped, face-sharing cubane units (each with one missing edge) wherein the metal atoms are octacoordinated with a distorted square-antiprismatic geometry. In a sol-gel treatment the amorphous xerogel obtained from 1 was transformed into a nano-crystalline product at 600 °C while the xerogel of Gd(OPri)3 under similar conditions required a heat treatment up to 900 °C for the same development.

Rac-Carbonyl{1-[(diphenylphosphino)methyl]ethanethiolato}(triphenylphosphine)rhodium(I)

The title compound, [Rh(C15H16PS)(C18H15P)(CO)], was synthesized from the reaction of the ligand rac-[Ph2PCH2CH(CH3)SH] with trans-[Rh(F)(CO)(PPh3)2] in a 1:1 molar ratio in toluene. The Rh atom is four-coordinated in a distorted square-planar geometry with the P—S ligand [Ph2PCH2CH(CH3)S] acting as a chelate and the PPh3 and disordered CO [site occupation factors of 0.61 (5) and 0.39 (5)] ligands completing the coordination.

Low‐temperature sol–gel transformation of methyl silicon precursors to silica‐based hybrid materials

AbstractSix new methyl silicon (IV) precursors of the type [MeSi{ONC(R)Ar}3] [when R = Me, Ar = 2‐C5H4N (1), 2‐C4H3O (2) or 2‐C4H3S (3); and when R = H, Ar = 2‐C5H4N (4), 2‐C4H3O (5) or 2‐C4H3S (6)] were prepared and structurally characterized by various spectroscopic techniques. Molecular weight measurements and FAB (Fast Atomic Bombardment) mass spectral studies indicated their monomeric nature. 1H and 13C{1H} NMR spectral studies suggested the oximate ligands to be monodentate in solution, which was confirmed by 29Si{1H} NMR signals in the region expected for tetra‐coordinated methylsilicon (IV) derivatives. Thermogravimetric analysis of 1 revealed the complex to be thermally labile, decomposing to a hybrid material of definite composition. Two representative compounds (2 and 4) were studied as single source molecular precursor for low‐temperature transformation to silica‐based hybrid materials using sol–gel technique. Formation of homogenous methyl‐bonded silica materials (MeSiO3/2) at low sintering temperature was observed. The thermogravimetric analysis of the methylsilica material indicated that silicon‐methyl bond is thermally stable up to a temperature of 400 °C. Reaction of 2 and Al(OPri)3 in equimolar ratio in anhydrous toluene yielded a brown‐colored viscous liquid of the composition [MeSi{ONC(CH3)C4H3O}3.Al(OPri)3]. Spectroscopic techniques 1H, 13C{1H}, 27Al{1H} and 29Si{1H} NMR spectra of the viscous product indicated the presence of tetracoordination around both silicon and aluminum atoms. On hydrolysis it yielded methylated aluminosilicate material with high specific surface area (464 m2/g). Scanning electron micrography confirmed a regular porous structure with porosity in the nanometric range. Copyright © 2008 John Wiley & Sons, Ltd.

Synthesis, spectroscopic and structural aspects of triphenylantimony(V) complex with internally functionalized acetylferroceneoxime: Crystal and molecular structures of [C 5H 5FeC 5H 4C(CH 3) [dbnd]NO] 2SbPh 3 and C 5H 5FeC 5H 4C(CH 3) [dbnd]NOH

Triorganoantimony(V) complex (C 5H 5FeC 5H 4C(CH 3) NO) 2SbPh 3 ( 1) has been prepared by the reaction of Ph 3SbCl 2 with acetylferroceneoxime C 5H 5FeC 5H 4C(CH 3) NOH ( 2) in 1:2 molar ratio in anhydrous toluene. The complexes have been characterized by elemental analyses, IR and NMR ( 1H and 13C) spectroscopic studies, and biologic activity was measured. And crystal structures of 1, 2 were reported. The coordination geometry around the antimony atom in 1 was slightly distorted trigonal bipyramidal with the carbon atoms of the SbPh 3 unit in equatorial positions and the two oxygen atoms of the oxime group occupying axial positions. The free oxime was clearly hydrogen bonded (H–N 2.10 Å/2.04 Å in 2) to essentially form a dimer.

Synthesis, characterization and reactivity of heteroleptic rare earth metal bis(phenolate) complexes

The synthesis, characterization and reactivity of heteroleptic rare earth metal complexes supported by the carbon-bridged bis(phenolate) ligand 2,2'-methylene-bis(6-tert-butyl-4-methyl-phenoxo) (MBMP2-) are described. Reaction of (C5H5)3Ln(THF) with MBMPH2 in a 1:1.5 molar ratio in THF at 50 degrees C produced the heteroleptic rare earth metal bis(phenolate) complexes (C5H5)Ln(MBMP)(THF)n (Ln=La, n=3 (); Ln=Yb (), Y (), n=2) in nearly quantitative yields. The residual C5H5- groups in complexes to can be substituted by the bridged bis(phenolate) ligands at elevated temperature to give the neutral rare earth metal bis(phenolate) complexes, and the ionic radii have a profound effect on the structures of the final products. Complex reacted with MBMPH2 in a 1:0.5 molar ratio in toluene at 80 degrees C to produce a dinuclear complex (MBMP)La(THF)(micro-MBMP)2La(THF)2 () in good isolated yield; whereas complexes and reacted with MBMPH2 under the same conditions to give (MBMP)Ln(MBMPH)(THF)2 (Ln=Yb (), Y ()) as the final products, in which one hydroxyl group of the phenol is coordinated to the rare earth metal in a neutral fashion. The reactivity of complexes and with some metal alkyls was explored. Reaction of complex with 1 equiv. of AlEt3 in toluene at room temperature afforded unexpected ligand redistributed products, and a discrete ion pair ytterbium complex [(MBMP)Yb(THF)2(DME)][(MBMP)2Yb(THF)2] () was isolated in moderate yield. Furthermore, reaction of complex with 1 equiv. of ZnEt2 in toluene gave a ligand redistributed complex [(micro-MBMP)Zn(THF)]2 () in reasonable isolated yield. Similar reaction of complex with ZnEt2 also afforded complex ; whereas the reaction of complex with 1 equiv. of n-BuLi in THF afforded the heterodimetallic complex [(THF)Yb(MBMP)2Li(THF)2] (). All of these complexes were well characterized by elemental analyses, IR spectra, and single-crystal structure determination, in the cases of complexes , and -.

Free-radical cross-linking copolymerization of methyl methacrylate and ethylene glycol dimethacrylate in the presence of trimethoxyvinylsilane

Free-radical cross-linking copolymerization of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDM), and trimethoxyvinylsilane (TMVS) has been investigated in toluene at a total monomer concentration of 4 mol L −1 and at 70 °C. Conversion of monomer, volume swelling ratio, weight fraction, and gel point were measured as a function of the reaction time, TMVS concentration, toluene content, temperature, and chain transfer agents up to the onset of macrogelation. Structural characteristics of the gels were examined by using equilibrium swelling in toluene, gel fraction, and Fourier transform infrared (FTIR) analysis. The morphology of the copolymers was also investigated by scanning electron microscopy (SEM). Based on the obtained results, it was concluded that the FTIR data did not have the capacity to show the presence of the TMVS moiety in these kinds of copolymers. On the other hand, the variation of weight fraction of gel, W g , and its equilibrium volume swelling ratio in toluene, q v , exhibited the same behaviors as that of MMA/EGDM copolymers. Also, the dilution of the monomer mixture resulted in an increase in the gel point and swelling degree and a decrease in the percent of conversion and gel fraction. Finally, TMVS is a suitable silicone co-monomer for this system and it has been proved useful.

Reactivity of Arsenic Trichloride and Glycolates with O,O′‐bis(ortho‐, meta‐ or para‐tolyl) Dithiophosphates

Reactions of arsenic trichloride and 2‐chloro‐1,3,2‐dioxarsolane or ‐dioxarsinane, sC1 (G=-CH2CH2- or -CH2CH2-CH2-), with sodium salt of O,O′‐bis(ortho‐, meta‐ or para‐tolyl) dithiophosphate ligands, (o‐, m‐ or p‐ MeC6H4O)2PS2Na, in different molar ratio in toluene under anhydrous conditions results in the formation of complexes corresponded to [{(o‐, m‐ or p‐MeC6H4O)2PS2}nAsCl3‐n] (n=1 or 2) and [(o-, m- or p- MeC6H4O)2 (n=2 or 3) in 83–93% yield. These yellow complexes were characterized by elemental analysis, molecular weight determinations, IR and NMR (1H, 13C and 31P) spectroscopic studies, which revealed monomeric nature of the complexes and anisobidentate mode of bonding of dithio moiety with arsenic atom, leading to a trigonal bipyramidal or octahedral geometry.