Hydrolysis of C,N‐chelated diorganotin(IV) chlorides and catalysis of transesterification reactions

Diorganotin(IV) dichlorides of formula L^CNRSnCl₂ (where R is nBu or Ph) containing one L^CN chelating ligand were hydrolyzed with aqueous sodium hydroxide in benzene. The composition of the products is strongly dependent on the amount of hydroxide. The partially hydrolyzed compounds of composition (L^CNRSnCl)₂(µ‐O) were isolated as crystalline products. A hydrolysis where more than one molar equivalent of NaOH is employed gave only a mixture of unidentifiable products. The structure of (L^CNPhSnCl)₂(µ‐O) was determined by X‐ray diffraction techniques in the solid state. In solution there was a mixture of diastereoisomers found, where the tin atoms serve as a stereogenic centers. The catalytic activity of starting dichlorides as well as (L^CNPhSnCl)₂(µ‐O) in various transesterification processes was investigated. The activity is very low in the case of starting dichlorides. When two molar equivalents of NaH are added or (L^CNPhSnCl)₂(µ‐O) is employed in the catalytic experiments, the activity is comparable to the literature data. Copyright © 2009 John Wiley & Sons, Ltd.     

Studies on the formation of PEN. I. Kinetic aspects of catalyzed reaction in transesterification of dimethylnaphthalate with ethylene glycol

The transesterification of dimethyl naphthalate (DMN) with ethylene glycol (EG) was kinetically investigated in the presence of various catalysts at 185°C. The transesterification was assumed to obey first-order kinetics with respect to DMN and EG, and a rate equation was derived. The rate constant of transesterification which was calculated from the quantity of methanol which distilled from the reaction vessel was used to evaluate the activity of each metal compound. The first-order dependence on the catalyst concentration is valid below a critical concentration which was found to be dependent on the catalyst type. The order of decreasing catalytic activity of various metal ions was found to be: Pb ≥ Zn > Co > Mg > Ni ≥ Sb, but in the case of highly basic metal salts, the rate constants were found to be extremely large at the initial stage of the reaction, and then rapidly decreased with the progress of the reaction. Effects of reaction temperature were also discussed. The activation energies for zinc acetate and lead acetate were 97.84 and 108.8 kJ/mol, respectively, which were calculated from the Arrhenius equation. © 1994 John Wiley & Sons, Inc.     

Organometallic complexes with biological molecules: V. In vivo cytotoxicity of diorganotin(IV)-amoxicillin derivatives in mitotic chromosomes of rutilus rubilio (pisces,cyprinidae)

In Order to test in vivo cytotoxicity of diorganotin(IV)-amoxicillin (amox) derivatives, mitotic chromosomes of Rutilus rubilio (Pisces, Cyprinidae) have been analyzed using two different chromosome-staining techniques. Results gathered after exposure of fish to the free amox · 3H₂O, R₂SnClamox · 2H₂O, and R₂Snamox · ₂ 2H₂O (R = methyl, butyl and phenyl; amox⁻ = 6-[D(−)-β-amino-p-hydroxyphenylacetamido]penicillinate) suggest that methyl derivatives seem to exert a lower cytotoxicity than butyl and phenyl ones and that R₂Snamox · ₂ 2H₂O deriva-tives are more toxic than R₂SnClamox · 2H₂O at both 10⁻⁵ and 10⁻⁷mol dm⁻³ concentrations. The following structural lesions have been iden-tified by comparative analysis of mitotic chromo-somes from untreated specimens (controls) and specimens treated with diorganotin(IV)-amoxicillin derivatives: (1) differentially stained chromosome areas; (2) granular deeply stained zones along the chromosomal body; (3) arm breakages; and (4) side-arm bridges (pseudochiasmata).     

Exploiting the versatility of pyridyl ligands for the preparation of diorganotin (IV) adducts: spectral,crystallographic and Hirshfeld surface analysis studies

Diorganotin (IV) complexes SnR₂X₂ (R = Me, Ph; X = Cl, NCS) form a series of versatile complexes when react with bidentate substituted pyridyl ligands. The reaction of dimethyltin dichloride with 5,5′‐dimethyl‐2,2′‐bipyridine (5,5′‐Me₂bpy) resulted in the formation of [SnMe₂Cl₂(5,5′‐Me₂bpy)] ( 1 ). Moreover, the reaction of SnMe₂(NSC)₂ with 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine (bu₂bpy), 1,10‐phenanthroline (phen) and 4,7‐diphenyl‐1,10‐phenanthroline (bphen) affords the hexa‐coordinated complexes [SnMe₂(NCS)₂(bu₂bpy)] ( 2 ), [SnMe₂(NCS)₂(phen)] ( 3 ) and [SnMe₂(NCS)₂(bphen)] ( 4 ), respectively. The resulting complexes have been characterized using elemental analysis, IR, multinuclear NMR (¹H, ¹³C, ¹¹⁹Sn) and DEPT‐135^° NMR spectroscopy. On the other hand, the reaction of diphenyltin dichloride with 2,2′‐biquinoline (biq) and 4,7‐phenantroline (4,7‐phen) led to the formation of polymeric complexes of [SnPh₂Cl₂(4,7‐phen)]_n ( 5 ) and [SnPh₂Cl₂(biq)]_n ( 6 ). The NMR spectra, however, reveal the ligand lability in solution and suggest a coordination number of 5 . The X‐ray crystal structures of complexes [SnMe₂Cl₂(5,5′‐Me₂bpy)] ( 1 ), [SnMe₂(NCS)₂(bu₂bpy)] ( 2 ) and [SnMe₂(NCS)₂(bphen)] ( 4 ) have been determined which reveal that the geometry around the tin atom is distorted octahedral with trans‐[SnMe₂] configuration. Interestingly, the crystal structure of (H₂biq)₂[SnPh₂Cl₄]?2CHCl₃ ( 7 ) was characterized by X‐ray crystallography from a chloroform solution of [SnPh₂Cl₂(biq)]_n ( 6 ) indicating the formation of doubly protonated [H₂biq]⁺ and [Ph₂SnCl₄]^2? which are stabilized by a network of hydrogen bonds with a feature of trans‐[SnPh₂]. The 3D Hirshfeld surface analysis and 2D fingerprint maps were used for quantitative mapping out of the intermolecular interactions for 1 , 2 , 4 and 7 which show the presence of π‐π and hydrogen bonding interactions which are associated between donor and acceptor atoms (N, S, Cl) in the solid state.     

The effect of molecular weight and catalyst concentration on catalytic activity in mechanochemically activated transesterification using silver(I)‐N‐heterocyclic carbene latent catalysts

We have investigated the effect of the concentration and molecular weight on the activity of polymeric silver(I)‐NHC (NHC = N‐heterocyclic carbene) catalyst complexes in ultrasound‐induced mechanochemical catalyst activation. A strong dependence of the turnover number (TON) on initial catalyst concentration was observed in the transesterification of vinyl acetate with benzyl alcohol. The main findings of this study are that the concentration and molecular weight effects on TON are caused by competition between mechanochemical catalyst activation and deactivation, most likely by reactive species produced during the sonication process. Performing the transesterification reaction under radical‐suppressing conditions resulted in a significant increase of TON. This result clearly demonstrates the increased catalyst lifetime when reducing the amount of sonochemical impurities, and it highlights the importance of controlling and suppressing secondary, sonochemical processes when using ultrasound‐induced mechanochemical generation of reactive species such as catalysts. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Insecticidal activity of some penta- and hexa-coordinated heterocyclic β-diketone derivatives of diorganotin(IV) against the stored product pest Rhizopertha (Coleoptera: Bostrichidae)

Some new penta-and hexa-coordinated diorganotin complexes of heterocyclic β-diketones having the general formula (n-C₄H₉)₂Sn(OPr¹)_2?n[RCOC:CON(C₆H₅) N:CCH₃]_n (where R?? CH₃, ? C₆H₅ and p-Cl? C₆H₄ and n = 1 and 2) have been synthesized and were screened for their insecticidal activity against Rhizopertha dominica (Fabricius), the lesser grain borer. The hexa-coordinated complexes have been observed to be more active than the penta-coordinated complexes.     

The photodecomposition of platinacycloalkanes in solution.: I. 1,3-propanediylplatinum(IV) compounds

The gaseous products of the photolysis at 25°C of the platinacyclobutane compounds [X₂$\text{PtCH}{}_2\text{CH}{}_2\text{C}$H₂(N-N)] where X = Cl, Br and N-N = 1,10-phenanthroline, 2,2′-bipyridine, (CH₂NMe₂)₂, (C₅H₅N)₂ in several solvents, in the absence and presence of various additives, have been determined. With solvents of relatively low dielectric constant (e.g. CH₂Cl₂), over 85 mol % of the hydrocarbon products was propene, the formation of which appears to involve a direct transfer of a hydrogen atom between neighbouring groups in the ring. With solvents of relatively high dielectric constant (MeCN, Me₂SO) in the presence of species, e.g. I^?, SbPh₃, having a high trans effect, cyclopropane is the main volatile product. The effect of added halide ion and of the mixed solvents Me₂SO/PhMe and Me₂SO/PhSH indicates that ionisation of the platinacyclobutane and the formation of platinum substituted propyl ion-radicals precede the formation of cyclopropane (and the small amounts of ethylene produced).The photolysis of [X₂$\text{PtCH}{}_2\text{CH}{}_2\text{C}$H₂(MeCN)₂] in methyl cyanide solution in the presence of Et₃RNX′ (X′ = Cl, R = H; X′ = Br, R = Et) gives appreciable amounts of ethylene in the products (up to 25 mol %). It is suggested that the halide ions add to the platinum to give negatively charged platinacyclobutane species, the photodecomposition of which may give C₂H₄.     

Studies on complex compounds of thorium(IV) with pyridine and quinoline carboxylic acid. Part I

Summary Thorium acetylacetonate [Th(acac)₄] reacts with pyridine carboxylic acids in acetone giving eight coordinate thorum(IV) complexes of the compositions [Th(pic)₄] and [Th(picO)₄] (picH = picolinic acid, picOH = picolinic acidN-oxide). The complex [Th(dip)₂] · 3H₂O (dipH₂ = pyridine-2,6-dicarboxylic acid) is also reported. Thorium(IV) complexes of the types [Th(quin)₂] · 2H₂O and [Th(quind)₂(acac)₂] (quinH₂ = quinolinic acid or pyridine-2,3-dicarboxylic acid, quindH = quinaldinic acid) were prepared by the interaction of [Th(acac)₄] with the respective acids in acetone. The lower solubility and i.r. spectral studies of the complex [Th(quin)₂] · 2 H₂O suggest that it is polymeric.     

Structure–reactivity studies of chloro and isothiocyanato diorganotin (IV) complexes based on multidentate N‐donor ligands: Synthesis,spectral characterization and crystal structures

The reaction of [SnMe₂Cl₂] with the bidentate ligand 4,7‐phenanthroline (4,7‐phen) resulted in the formation of [SnMe₂Cl₂ (4,7‐phen)]_n ( 1a ) which is probably a polymeric chain in solution. On the other hand, the reaction of [SnEt₂Cl₂] with 4,7‐phen afforded the complex [Sn₂Et₄Cl₄ (κ¹‐N‐4,7‐phen)₂(μ‐κ²‐N,N‐4,7‐phen)] ( 1b ) which dissociates in dimethylsulfoxide solution. The reaction of [SnR₂Cl₂] (R = Me, Et) with 2,2′‐biquinoline (biq) yielded the complexes [SnMe₂Cl₂ (κ²‐N,N‐biq)] ( 2a ) and [SnEt₂Cl₂ (κ¹‐N‐biq)₂] ( 2b ) in the solid state. Moreover, the reaction of [SnR₂Cl₂] (R = Me, Et) with the tridentate ligand 4′‐(2‐furyl)‐2,2′:6′,2″‐terpyridine (ftpy) resulted in the formation of ionic penta‐ and hexa‐coordinated tin complexes [SnMe₂Cl (ftpy)][SnMe₂Cl₃] ( 3a ) and [SnEt₂Cl (ftpy)]Cl ( 3b ). The reaction of [SnMe₂ (NCS)₂] with ftpy afforded the hepta‐coordinated complex [SnMe₂ (NCS)₂(ftpy)] ( 4a ). The products were fully characterized using elemental analysis, and infrared, UV–visible, multinuclear (¹H, ¹³C, ¹¹⁹Sn) NMR, DEPT‐135°, HH‐COSY and HSQC NMR spectroscopies. The crystal structure of complex 3a reveals that it contains the simultaneous presence of penta‐ and hexa‐coordinated tin (IV) atoms. Notably, the crystal structure of complex 4a shows that tin (IV) is hepta‐coordinated in a pentagonal bipyramidal geometry SnC₂N₅ by three nitrogen atoms of ftpy, two nitrogen atoms of NCS^? and two Me groups with trans‐[SnMe₂] configuration. These data indicate the influence of halide or pseudo‐halide group on the coordination number and geometry of tin. Hirshfeld surface analysis and two‐dimensional fingerprint plots were calculated for 3a and 4a which show the π–π interaction between molecules in the solid is relatively weak.     

Studies on C-heterocyclic tin compounds. The synthesis and spectral characterization of some thienyl tetraorganotin(IV) compounds

The synthesis of a series of tetraorganotin(IV) compounds containing selectively the 2-thienyl, 3-thienyl, 5-methyl-2-thienyl, 5-t-butyl-2-thienyl, 4-methyl-2-thienyl and 3-(2-pyridyl)-2-thienyl groups [L], of formula R_4-nSn[L]_n (R = Ph, p-tolyl, Me, cyclopentyl, cyclohexyl; n = 1–4) is reported. Features of structural interest deduced from ^119mSn Mössbauer and NMR (¹³C and ¹¹⁹Sn modes) spectra are considered.     

Studies on the reaction of organotin phenoxides with ethyl propiolate catalysed by triethylamine and tin(IV) chloride

Different tributyltin phenoxides react at room temperature with ethyl propiolate in benzene, in the presence of tin(IV) chloride, triethylamine and their mixture to give the derivatives of 3‐phenoxyacrylic acid ethyl ester. Exceptionally, 3‐(2‐hydroxyphenyl)acrylic acid ethyl ester and 3‐(2‐hydroxy‐5‐methylphenyl)acrylic acid ethyl ester have been obtained from the reaction of tributylphenoxytin and tributyl(p‐tolyloxy)tin, respectively catalysed by SnCl₄, and they have been easily hydrolysed to coumarin and 6‐methylcoumarin. Copyright © 2007 John Wiley & Sons, Ltd.     

Speciation of phenyltin(IV) compounds using high‐performance liquid chromatography: Part 1. The direct analysis of mixed standard solutions of tetraphenyltin,triphenyltin chloride,triphenyltin hydroxide and triphenyltin acetate

A rapid speciation high‐performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of phenyltin compounds. The commercially important products of triphenyltin‐chloride, ‐acetate, ‐hydroxide and tetraphenyltin were separated by reversed‐phase HPLC on a Waters Spherisorb S5W ODS‐2 (octadecylsilica) column using an isocratic mixture of 90:10 (v/v) acetonitrile:water as the mobile phase at a flow rate of 1 ml min^?1. The phenyltin compounds were detected by UV detection at 254 nm and the total elution time is 8 min. The elution order is triphenyltin‐chloride, ‐acetate, ‐hydroxide and tetraphenyltin. Detection limits were 0.01 ppm for each of the triphenyltin compounds and 0.02 ppm for tetraphenyltin. Spiked water samples containing the three biocidal triphenyltin compounds could also be analysed simultaneously by the above method without the need for any prior derivatization, following extraction with toluene. The versatility of the method in sensing substituent group variations on the phenyl ring was also demonstrated by the successful resolution of the hydroxides, tris(p‐chlorophenyl)tin hydroxide, diphenyl(p‐chlorophenyl)tin hydroxide and triphenyltin hydroxide. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis,structural characterization and antimicrobial activity of mixed aryl–alkyl diorganotin(IV) compounds with quinoline‐2‐carboxylate (L−): {RR′SnLCl}n and RR′SnL2

A series of unsymmetrical diorganotin derivatives of quinoline‐2‐carboxylic acid (LH), namely polymeric {MePhSnClL}_n (1) and {EtPhSnClL}_n (2), and mononuclear MePhSnL₂ (3) and EtPhSnL₂ (4), was synthesized by the reaction of LH with the MePhSnCl₂, EtPhSnCl₂, MePhSnO, and EtPhSnO precursors, respectively. The compounds were characterized by elemental analysis and infrared spectroscopy, as well as by ¹ H, ¹³ C and ¹¹⁹Sn NMR. The molecular structures of representative compounds 2 and 4 were determined by single‐crystal X‐ray crystallography. This study showed that polymeric 2 adopts a distorted octahedral geometry as the carboxylate ligand N,O chelates an Sn atom and at the same time bridges a neighbouring Sn atom via the second O atom, with the remaining sites being occupied by the Cl and two C atoms; the O atoms are trans to each other. The result of the μ₂‐bridging mode of L^? is the formation of a supramolecular helical chain. Compound 4 adopts a skew‐trapezoidal bipyramidal geometry with the organo groups lying over the plane of the two N,O‐chelating carboxylate ligands and being directed over the weaker Sn―N bonds. The in vitro antimicrobial activities of 1–4 against a Gram‐positive bacteria strain (Bacillus subtilis), a Gram‐negative bacteria strain (Escherichia coli) and against Candida albicans were studied and compared with the antimicrobial activities of Ph₂SnL₂ and Me₂SnL₂, and with the antimicrobial standards gentamicin, tetracycline, ampicillin and penicillin. All organotin compounds displayed remarkable antibacterial activities that were comparable to those of the standard drugs, in particular against B. subtilis, where the activity was correlated with the number of Cl substituents. Copyright © 2012 John Wiley & Sons, Ltd.     

Studies on ABX6 Compounds. IV. The structures of AUI6 compounds (A: Sr,Eu, Ba)

The compounds SrUI₆, EuUI₆ and BaUl₆ are synthesized for the first time. Their crystal structures are isotypic, and they can be described as ordered substitution variants of the AlCl₃ type.     

Complexes of organometallic compounds. XXXVIII. Anion Exchange Studies on the Trimethyllead (IV) Thiocyanate aqueous complex system

The distribution of Me₃Pb^IV between the anion exchange resin Dowex 1 X 8 and aqueous solutions of NaSCN and KSCN was investigated. In the aqueous phase, up to 3 M thiocyanate concentration, only the formation of the neutral species Me₃PbNCS was detected and the related stability constant evaluated. Evidence of formation into the resin phase of the anionic Me₃Pb(NCS) species was obtained.     

Transformation of organic compounds in the presence of metal complexes: II. Reduction of alkyl-substituted cyclohexanones via hydrogen-transfer reactions catalysed by rhodium(I) complexes

Catalyst systems prepared in situ from bidentate phosphines (Ph₂P(CH₂)_nPPh₂, where n = 1–4) and from [Rh(COD)Cl]₂ proved to be active in the transfer hydrogenation of alkylcyclohexanones (alkyl = 2-Me, 4-Me, 4-t-Bu, cis-2,6-Me₂). With the exception of 4-methylcyclohexanone, which gave a cis/trans-cyclohexanol ratio of ～ 1, mainly cis alcohols were formed, their amounts increasing in proportion to the value of n. No reduction occurred in the case of 2-t-butyl- and 2,6-di-t-butyl-cyclohexanones.     

双核Cu(I)配合物的热分解非等温动力学

Thermal decomposition process of four benzimidazolyl-containing dicopper(Ⅰ) complexes: [Cu2(OCTB)](ClO4)2•1.5H2O(1), [Cu2 (NMOCTB)](ClO4)2•H2O(2), [Cu2(NBUOCTB)](ClO4)2(3), [Cu2(NBOCTB)](ClO4)2•H2O(4) and their kinetics were studied under the non-isothermal conditions by TG-DTG techniques. The non-isothermal kinetic data were analyzed by means of Achar and Coats-Redfern method respectively. The kinetic equation for the second step of the decomposition of complex (1) can be expressed as: dα/dt=A•exp(-E/RT) •(1-α), the mechanism of this reaction corresponds to "Coring and Growth" with n=1; while for the first step of complex (3) decomposition, dα/dt=A•exp(-E/RT)• (1-α)2, which corresponds to the mechanism of "the second-order chemical reaction".     

Mechanistic study on gold(I)‐catalyzed crosscoupling of diazo compounds: A DFT study

The reaction mechanisms of the gold(I)‐catalyzed cross‐coupling reaction of aryldiazoacetate R1 with vinyldiazoacetate R2 leading to N‐substituted pyrazoles have been theoretically investigated using density functional theory calculations. Two possible reaction mechanisms were examined and discussed. The preferred reaction mechanism (mechanism A) can be characterized by five steps: the formation of the gold carbenoid A2 via the attack of catalyst to R1 (step I), nucleophilic addition of another reactant R2 to generate intermediate A3 (step II), intramolecular cyclization of A3 to form intermediate A4 (step III), hydrogen migration to give intermediate A5 (step IV), and catalyst elimination affording the final product P1 (step V). Step IV is found to be the rate‐determining step with an overall free energy barrier of 28.3 kcal/mol. Our calculated results are in good agreement with the experimental observations. The present study may provide a useful guide for understanding these kinds of gold(I)‐catalyzed cross‐coupling reactions of diazo compounds.