C,N-chelated hexaorganodistannanes, and triorganotin(IV) hydrides and cyclopentadienides

Triorganotin(IV) hydrides and cyclopentadienides as well as hexaorganodistannanes containing the moiety L^CN (2-(N,N-dimethylaminomethyl)phenyl-) as chelating ligand and phenyl, n-butyl or t-butyl substituents were prepared and characterized by NMR and XRD. The compounds reveal trigonal bipyramidal geometry around the central tin atom except for the distannanes in which the tin atom has tetrahedral configuration. The di-n-butyl distannane cannot be oxidized by oxygen or heavier chalcogens and give no tin radical when irradiated by UV light or treated with the TEMPO - free radical at room temperature. L^CN(t-Bu)₂SnH undergoes reaction in solution toward the corresponding distannane. The hydrostannation reaction of L^CN(n-Bu)₂SnH with ferrocenylacetylene was investigated. The CO₂ activation by L^CN(n-Bu)₂SnH was also examined.     

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.     

Structure and properties of double‐C,N‐chelated tri‐ and diorganotin(IV) halides

Tri‐ and di‐organotin(IV) compounds containing one or two 2‐(dimethylaminomethyl)phenyl‐ (L^CN) groups as chelating ligands were prepared by reactions of lithium compound L^CNLi with an appropriate amount of (organo)tin halide. The geometry of tin in 1 ((L^CN)₂SnPhCl) is on the boundary between octahedral and trigonal bipyramidal. The diorganotin compounds 2–4 ((L^CN)₂SnX₂, where X = Cl, Br, I) have a distorted octahedral geometry in the solid state and show dynamic processes in solution with a lowering of activation energy of the dynamic process going from diiodide to dichloride derivative. Compound 5 (L^CNSnPhCl₂) has a trigonal bipyramidal structure with non‐equivalent chlorine atoms. Copyright © 2005 John Wiley & Sons, Ltd.     

S,N‐Chelated organotin(IV) compounds containing 6‐phenylpyridazine‐3‐thiolate ligand—structural,antibacterial and antifungal study

A series of tri‐ and diorganotin(IV) compounds containing potentially chelating S,N‐ligand(s) (L^SN, where L^SN is 6‐phenylpyridazine‐3‐thiolate) were prepared and structurally characterized by multinuclear NMR spectroscopy. X‐ray diffraction techniques were used for determination of the structure of compounds containing one [(L^SN)Ph₂SnCl], two [(n‐Bu)₂Sn(L^SN)₂] and the combination of two L^SN and one L^CN [(L^CN)(n‐Bu)Sn(L^SN)₂] (where L^CN is {2‐[(CH₃)₂NCH₂]C₆H₄}‐) ligands. The coordination number of the tin atom varies from five to seven and is dependent on the number of chelating ligands present. The formation of the five‐membered azastanna heterocycle is favored over the formation of four‐membered azastannathia heterocycle in compounds containing both types of ligands. The di‐n‐butyl‐substituted compounds are the most efficient ones in inhibition of growth of yeasts, molds and G⁺ bacteria strains. Copyright © 2011 John Wiley & Sons, Ltd.     

C,N-chelated organotin(IV) trifluoroacetates. Instability of the mono- and diorganotin(IV) derivatives.

The C,N-chelated tri-, di- and monoorganotin(IV) halides react with equimolar amounts of CF₃COOAg to give corresponding C,N-chelated organotin(IV) trifluoroacetates. The set of prepared tri-, di- and monoorganotin(IV) trifluoroacetates bearing the L^CN ligand (where L^CN is 2-(N,N-dimethylaminomethyl)phenyl-) was structurally characterized by X-ray diffraction analyses, multinuclear NMR and IR spectroscopy. In the case of triorganotin(IV) trifluoroacetates and (L^CN)₂Sn(OC(O)CF₃)₂, no tendency to form hydrolytic products, or instability towards the moisture was observed. L^CNRSn(OC(O)CF₃)₂ (where R is n-Bu or Ph) and L^CNSn(OC(O)CF₃)₃ forms upon crystallization from THF in the air mainly dinuclear complexes in which the two tin atoms are interconnected either by hydroxo-bridges or by an oxo-bridge and/or by a bridging trifluoroacetate(s). In the case of hydrolysis of L^CN(n-Bu)Sn(OC(O)CF₃)₂, a zwitterionic stannate of formula L^CN(n-Bu)Sn(OC(O)CF₃)₂·CF₃COOH was isolated from the mother liquor, too. Products of hydrolysis of L^CN(n-Bu)Sn(OC(O)CF₃)₂ and L^CNSn(OC(O)CF₃)₃, and some other oxygen bridged organotin(IV) compounds containing the same ligand, were tested as possible catalysts of some transesterification reactions as well as in direct dimethyl carbonate (DMC) synthesis from CO₂ and methanol.     

Organotin(IV) complexes derived from proteinogenic amino acid: synthesis,structure and evaluation of larvicidal efficacy on Anopheles stephensi mosquito larvae

Five new organotin(IV) complexes of composition [Bz₂SnL¹]_n ( 1 ), [Bz₃SnL¹H⋅H₂O] ( 2 ), [Me₂SnL²⋅H₂O] ( 3 ), [Me₂SnL³] ( 4 ) and [Bz₃SnL³H]_n ( 5 ) (where L¹ = (2S )‐2‐{[(E )‐(4‐hydroxypentan‐2‐ylidene)]amino}‐4‐methylpentanoate, L² = (rac )‐2‐{[(E )‐1‐(2‐hydroxyphenyl)methylidene]amino}‐4‐methylpentanoate and L³ = (2S )‐ or (rac )‐2‐{[(E )‐1‐(2‐hydroxyphenyl)ethylidene]amino}‐4‐methylpentanoate) were synthesized and characterized using ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR and infrared spectroscopic techniques. The crystal structure of 2 reveals a distorted trigonal‐bipyramidal geometry around the tin atom where the oxygen atoms of the carboxylate ligand and a water ligand occupy the axial positions, while the three benzyl ligands are located at the equatorial positions. On the other hand, the analogous derivative of enantiopure L³H ( 5 ) consists of polymeric chains, in which the ligand‐bridged tin atoms adopt the same trans ‐Bz₃SnO₂ trigonal‐bipyramidal configuration and are now coordinated to a phenolic oxygen atom instead of H₂O. In 2 , the OH hydrogen of the ketoimine substituent has moved to the nearby nitrogen atom while in the salicylidene derivative 5 , the OH is located almost midway between the phenolic oxygen atom and the nitrogen atom of the CN group. For the dibenzyltin derivative 1 , a polymeric chain structure is observed as a result of a long intermolecular Sn⋅⋅⋅O bond involving the exocyclic carbonyl oxygen atom from the tridentate ligand of a neighbouring tin‐complex unit. The tin atom in this complex has distorted octahedral coordination geometry. In contrast, the racemic dimethyltin(IV) complexes 3 and 4 display discrete monomeric structures with a distorted octahedral‐ and trigonal‐bipyramidal geometry, respectively. The structures show that the coordination mode of the Schiff base ligand depends primarily on the number of bulky benzyl ligands (R) at the tin atom, as indeed found in the structures of related complexes where R = phenyl. With three bulky R groups, the tridentate chelating O,N,O coordination mode is preferred, whereas with fewer or less bulky R ligands, only the carboxylate and hydroxy groups are involved, which leads to polymers. Larvicidal efficacies of two of the new tribenzyltin(IV) complexes ( 2 and 5 ) were assessed on the second larval instar of Anopheles stephensi mosquito larvae and compared with two triphenyltin(IV) analogues, [Ph₃SnL¹H]_n and [Ph₃SnL³H]_n . The results demonstrate that the compounds containing Sn–Ph ligands are more effective than those with Sn–Bz ligands. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis, structural characterization and electrochemistry of C,N-chelated organotin(IV) dicarboxylates with ferrocenyl substituents

A set of C,N-chelated organotin(IV) ferrocenecarboxylates, [L^CN(n-Bu)Sn(O₂CFc)₂] (1), [(L^CN)₂Sn(O₂CFc)₂] (2), [L^CN(n-Bu)Sn(O₂CCH₂Fc)₂] (3), [L^CN(n-Bu)Sn(O₂CCH₂CH₂Fc)₂] (4), [L^CN(n-Bu)Sn(O₂CCHCHFc)₂] (5), [L^CN(n-Bu)Sn(O₂CfcPPh₂)₂] (6), [(L^CN)₂Sn(O₂CfcPPh₂)₂] (7), and [L^CN(n-Bu)₂Sn(O₂CFc)] (8) (L^CN = 2-(N,N-dimethylaminomethyl)phenyl, Fc = ferrocenyl and fc = ferrocene-1,1′-diyl) has been synthesized by metathesis of the respective organotin(IV) halides and carboxylate potassium salts and characterized by multinuclear NMR and IR spectroscopy. The spectral data indicated that the tin atoms in diorganotin(IV) dicarboxylates bearing one C,N-chelating ligand (1 and 3-6) are seven-coordinated with a distorted pentagonal bipyramidal environment around the tin constituted by the n-butyl group, the chelating L^CN ligand and bidentate carboxylate. Compounds 2 and 7 possessing two chelating L^CN ligands comprise octahedrally coordinated tin atoms and monodentate carboxylate donors, whereas compound 8 assumes a distorted trigonal bipyramidal geometry around tin with the carboxylate binding in unidentate fashion. The solid state structures determined for 1⋅C₆D₆ and 2 by single-crystal X-ray diffraction analysis are in agreement with spectroscopic data. Compounds 1, 3-5, and 8 were further studied by electrochemical methods. Whereas the oxidations of ferrocene units in bis(carboxylate) 2 and monocarboxylate 8 proceed in single steps, compound 1 undergoes two closely spaced one-electron redox waves due to two independently oxidized ferrocenyl groups. The spaced analogues of 2, compounds 3-5, again display only single waves corresponding to two-electron exchanged.     

Coordination polymers based on building blocks of dimethyltin(IV) Chloride iso‐thiocyanate and dimethyltin(IV) di‐iso‐thiocyanate with pyrazine‐2‐carboxylate and 4, 4′‐bipyridine

The reaction of 4,4′‐bipy with dimethyltin(IV) chloride iso‐thiocyanate affords the one‐dimensional (1D) coordination polymer, [Me₂Sn(NCS)Cl·(4,4′‐bipy)]_n ( 1 ), whereas reaction of dimethyltin(IV) dichloride with sodium pyrazine‐2‐carboxylate in the presence of potassium iso‐thiocyanate affords the two‐dimensional (2D) coordination polymer, {[Me₂Sn(C₄H₃N₂COO)₂]₂ [Me₂Sn(NCS)₂]}_n ( 2 ). Both coordination polymers were characterized by elemental analysis and infrared spectroscopy in addition to ¹H and ¹³C NMR spectroscopy of the soluble coordination polymer ( 1 ). A single‐crystal structure determination showed that the asymmetric unit in 1 contains Me₂Sn(NCS)Cl and 4,4′‐bipy moieties and a 1D infinite rigid chain structure forms through bridging of the 4,4′‐bipy ligand between tin atoms and the geometry around the tin atom is a distorted octahedral. Coordination polymer 2 contains two distinct tin atom geometrics in which one tin atom is seven coordinate, and the other is six coordinate. The two tin atom environments are best described as a pentagonal bipyramidal in the former and distorted octahedral in the latter where the carboxylate groups bridge the two tin atoms and construct a 2D‐coordination polymer. The ¹¹⁹Sn NMR spectroscopy indicates the octahedral geometry of 1 retains in solution. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:699–706, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/.20736     

Tri- and diorganostannates containing 2-(N,N-dimethylaminomethyl)phenyl ligand

The C,N-chelated tri and diorganotin(IV) chlorides react with both protic mineral acids and carboxylic acids. The nitrogen atom of the L^CN ligand (where L^CN is 2-(dimethylaminomethyl)phenyl) is thus quarternized - protonated and new Sn-X bond (X = Cl, Br, I or the remainder of the starting acid used) is simultaneously formed. The set of zwitterionic tri and diorganostannates containing protonated 2-(dimethylaminomethyl)phenyl-moiety was prepared and structurally characterized by multinuclear NMR spectroscopy and XRD techniques. In all these cases, the intramolecular N-H?X bond is present in the molecule. Despite the central tin atom remains five-coordinated (except for the [HL^CNH]⁺[(n-Bu)₂SnCl(NO₃)₂]⁻) and reveals a distorted trigonal bipyramidal geometry, the ¹¹⁹Sn NMR chemical shift values of these zwitterionic stannates are somewhat shifted to the higher field than corresponding starting C,N-chelated tri and diorganotin(IV) halides. Reactions of C,N-chelated organotin(IV) halides with various Lewis acids are also discussed.     

Synthesis and structures of cadmium(II) complexes of a series of multinucleating N/S donor ligands

The coordination chemistry of a series of bis-bidentate ligands with cadmium(II) ions has been investigated. The ligands, containing two N,S-donor chelating (pyrazolyl/thioether) fragments, have afforded complexes of a variety of structural types (dinuclear M₂L₂ ‘mesocate’ complexes, a one-dimensional chain coordination polymer and a simple mononuclear complex) according to whether the bis-bidentate ligands act as bridges spanning two metal ions, or a tetradentate chelate to a single metal ion. The p-phenylene and m-biphenyl spaced ligands L¹ and L³ form dinuclear M₂L₂ complexes where the ligands are arranged in a ‘side-by-side’ fashion. In contrast the m-phenylene spaced ligand L² forms a one-dimensional coordination polymer where the ligands adopt a highly folded conformation. The 1,8-naphthalene spaced ligand L⁴ adopts a tetradendate chelating mode and affords a simple mononuclear complex.     

Synthese,Kristallstrukturen und Eigenschaften von Lanthanoid(III)-Komplexen mit 7-Oxa-bicyclo[2.2.1]heptan-2,3-dicarbonsäure

Synthesis, Crystal Structures, and Properties of Lanthanoid(III) Complexes with 7-Oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic Acid The synthesis of coordination compounds [ML(HL)(H₂O)] with M = La³⁺, Ce³⁺, Pr³⁺, Nd³⁺ and H₂L = 7-oxa-bicyclo[2.2.1]heptane-2-exo,3-cis-dicarboxylic acid ( 1 ) has been described. Results of IR spectroscopy and thermal decomposition are given. As a result of X-ray analyses, the four investigated lanthanoid(III) complexes are isotypic. Their stereochemistry approximates to the tri-capped trigonal prism with nine O atoms coordinating the metal atom. The bicyclic ligand acts as a tridentate chelating monoanion HL^? as well as a pentadentate dianion L^2? with both chelating and bridging function. One coordination place at the metal atom is occupied by a water molecule.     

Über zinn-haltige heterocyclen : V. Sn-phenyk-substituierte stannocane, Übergänge von tetraedrischer 4-Zu trigonal-bipyramidaler 5-koordination

A complete series of diphenyl and mixed methyl/chlorine/bromine/iodinephenyl substituted oxadithia- and trithiastannocanes has been prepared by reactions between the respective disodium dithiolates and tin dihalides. The ¹³C NMR chemical shifts of these compounds and the coupling constants J(¹¹⁹Sn¹³C) are dependent upon the magnetic anisotropy of the substituents and the bond angles at the tin atom. The crystal structure of 2,2-diphenyl-1,3,6-trithia-2-stannocane has been determined and refined to R = 0.039. The environment of Sn is a monocapped tetrahedron (transannular distance Sn?S 324.6(1) pm). This type of coordination, intermediate between a tetrahedron and a trigonal bipyramid, is discussed quantitatively and compared with a series of analogous compounds. The eight-membered ring has the boat-chair conformation.     

Diphenyltin(IV) complexes of the 2-quinolinecarboxaldehyde Schiff bases of S-methyl- and S-benzyldithiocarbazate (Hqaldsme and Hqaldsbz): X-ray crystal structures of Hqaldsme and two conformers of its diphenyltin(IV) complex

New organometallic tin(IV) complexes of the empirical formula Sn(NNS)Ph₂Cl (NNS = anionic forms of the 2-quinolinecarboxaldehyde Schiff bases of S-methyl- and S-benzyldithiocarbazate) have been prepared and characterized by IR, electronic, ¹H NMR and ES mass spectroscopic techniques. The molecular structures of the 2-quinolinecarboxaldehyde Schiff base of S-methyldithiocarbazate (Hqaldsme) and its diphenyltin(IV) complex, Sn(qaldsme)Ph₂Cl, have been determined by X-ray diffraction. In the solid state, the ligand remains as the thione tautomer in which the dithiocarbazate chain adopts an E,E configuration and is almost coplanar with the quinoline ring. The Sn(qaldsme)Ph₂Cl complex crystallizes in two distinctly different conformationally isomeric forms, each having the same space group but different lattice parameters. X-ray analysis shows that in each polymorph, the tin atom adopts a distorted octahedral geometry with the Schiff base coordinated to it as a uninegatively charged tridentate chelating agent via the quinoline nitrogen atom, the azomethine nitrogen atom and the thiolate sulfur atom. The two phenyl groups occupy axial positions and the chloride ligand occupies the sixth coordination position of the tin atom. The deprotonated ligand adopts an E,E,Z configuration in the complex.     

Synthesis,characterization, and insecticidal activity of new tin (IV) complexes

A three-component reaction of dimethyltin dibromide with imidazo[1,2-a]pyridine, pyridine derivatives, or isoquinoline and allyl bromide in refluxing ethanol affords the ionic complex, bis(1-allylcycloiminium) dimethyltetrabromostannate (II). The reaction involves N-allylation of cycloimine accompanied by the coordination of two bromide ions with the tin atom of dimethyltin dibromide. The complexes have been characterized by infrared and ¹H NMR, ¹³C NMR, and ¹¹⁹Sn NMR studies. The X-ray crystal structure analysis of a complex reveals the tin atom to be hexacoordinated and the dimethyltetrabromostannate (II) anion having octahedral geometry. Some of the complexes tested for their insecticidal activity are found to exhibit strong activity against Tribolium castaneum insect with LC₅₀ ranging from 0.4 to 0.8 ppm.     

Heptacoordinated diphenyllead; hexa- and pentacoordinated triphenyllead and tin compounds derived from 5H-benzimidazo[1,2-c]quinazoline-6-thione

Heptacoordinated diphenyllead; hexa- and pentacoordinated triphenyllead and tin compounds derived from 5H-benzimidazo[1,2-c]quinazoline-6-thione are reported. The same molecular structures were found in solution by ¹¹⁹Sn and ²⁰⁷Pb NMR and in the solid state by X-ray diffraction analysis. The ligand was bound through S and N giving a four-membered ring. Due to the tension of the chelate ring in the penta- and hexacoordinated compounds, the nitrogen approaches the metal atom from an oblique direction giving a weak coordination. Hexacoordinated metal atoms were obtained by Lewis bases coordination to the polycyclic tin and lead compounds, which was possible because the M-phenyl groups form a cavity that allows the bases to approach from the opposite direction to the sulfur atom. In some crystals, two molecules formed a cavity where a solvent molecule was included. A heptacoordinated diphenyllead bound to two ligands and having the less common pentagonal bipyramidal geometry and cis-mer configuration with two sulfur atoms lying very close together was obtained.     

Biocidal Organotin Compounds. Part 2. Synthesis,Characterization and Biocidal Properties of Triorganotin(IV) Hydantoic Acid Derivatives and the Crystal Structures of Triphenyltin and Tricyclohexyltin Hydantoates

The preparation and spectroscopic (¹H NMR, UV and IR) characterization of three R₃Sn(O₂CCH₂N(H)C(O)NH₂) [R=Ph, c-Hex (cyclohexyl) or n-Bu] compounds are reported. A different mode of coordination is indicated for the hydantoate ligand in the R=Ph compound compared with the R=c-Hex and R=n-Bu compounds, as confirmed by a crystallographic analysis. The structure of [Ph₃Sn(O₂CCH₂N(H)C(O)NH₂)] is polymeric owing to the presence of bridging hydantoate ligands such that each ligand coordinates one tin atom, via one of the carboxylate oxygen atoms, and a symmetry-related tin atom via the carbonyl group at the other end of the molecule. The structure features distorted trigonal-bipyramidal tin atom geometries with a trans -R₃SnO₂ motif. The structure of [c-Hex₃Sn(O₂CCH₂N(H)- C(O)NH₂)], by contrast, is monomeric, distorted tetrahedral, as the carboxylate group is monodentate and there are no additional tin–ligand interactions. The structures are each stabilized by a number of intermolecular hydrogen bonds. Fungitoxicity and phytotoxicity studies indicate that the R=n-Bu derivative is the more active compound.     

Synthesis, structure and cytotoxicity of diorganotin(IV) complexes of 2,6-lutidine-α,3-diol (Lu): The crystal structures of Lu and [SnMe2(H2O)(Lu-2H)]

The reaction of dimethyl-, diethyl- and dibutyltin(IV) oxide with 2,6-lutidine-α²,3-diol (Lu) [2-(hydroxymethyl)-3-hydroxy-6-methylpyridine] in toluene/ethanol has been investigated. The compounds were isolated and characterized by IR, Raman and Mössbauer spectroscopy, EI and FAB mass spectrometry and ¹H and ¹¹⁹Sn NMR spectroscopy. The structures of Lu and [SnMe₂(H₂O)(Lu-2H)] were determined by X-ray diffraction. The crystal of [SnMe₂(H₂O)(Lu-2H)] contains dimeric [SnMe₂(H₂O)(Lu-2H)]₂ units, in which the tin atom is coordinated to the O atoms of the two deprotonated hydroxymethyl groups and one deprotonated phenolic hydroxyl group. The distorted octahedral coordination polyhedron of each tin atom is completed by a water molecule and two methyl C atoms. The butyl derivative exhibited significant in vitro antitumor activity against the human carcinoma cell lines HeLa-229, A2780 and A2780cis, although minor than that of the pyridoxine derivative prepared previously.     

The differences in solid state structures of C,N-chelated nbutyltin(IV) fluorides

The solid state structures of products of fluorination of L^CNnBuSnCl₂ (where L^CN is 2-[(CH₃)₂NCH₂]C₆H₄-) by different methods are reported. The reaction of 3 equiv. of [NH₄]⁺[L^CNnBuSnF₃]⁻ and Pr(OTf)₃ led to dimeric arrangement [L^CNnBuSnF(μ-F)₂SnL^CNnBuF] · 2HOTf. Two different polymorphs of polymeric [L^CNnBuSnF₂]_n have been obtained by crystallization. Prepared compounds were studied by X-ray crystallographic methods, DSC and theoretical calculations at the B3LYP/LANL2DZ level.     

Dimethyltin(IV) complexes with zwitterionic buffers (Mes and Mops)

Equilibrium studies in aqueous solution are reported for dimethyltin(IV) complexes of the zwitterionic buffers “Good’s buffer”, such as Mes and Mops (L). Stoichiometry and stability constants for the complexes formed were determined at different temperature and ionic strength 0.1 M NaNO₃. The results showed the best fit of the titration curves were obtained when complexes ML, MLH₋₁, MLH₋₂, and MLH₋₃ were expected beside the hydrolysis products of the dimethyltin(IV) cation. The thermodynamic parameters ΔH°, ΔS° and ΔG° calculated from the temperature dependence of the formation constant of the dimethyltin(IV)-Mes complex was investigated. The effect of dioxane as a solvent on the formation constants of dimethyltin(IV)-Mes complex was discussed. The concentration distribution of the various complex species was evaluated as a function of pH. The bonding sites of the dimethyltin(IV) complexes in solid state with Mes and Mops were characterized by means of elemental analyses and FTIR. The NMR (¹H, ¹³C) spectra of the DMT-Mes complex exhibits the strongly distorted octahedron geometry around tin atom. Also, thermal analyses (TGA and DTA) were discussed. Thermodynamic parameters such as activation energy (E_a), pre-exponential factor (A), entropy of activation (ΔS^∗) and free energy of activation (ΔG^∗) have been calculated for each step, employing integral method Coats and Redfern. The reaction enthalpy (ΔH) is obtained from DTA data.     

Studies of the reaction of dimethyltin dichloride with mercaptoacetic acid in the presence of amines and crystal structure of [(n-Pr)3NH][Me2Sn(μ-SCH2COO)Cl]

A series of new five-coordinated ionic organotin(IV) complexes with general formula [Q][Me₂Sn(μ²-SCH₂COO)Cl](Q = diethylammonium, triethylammonium, di-i-propylammonium, tripropylammonium, tri-n-butylammonium, pyrimidium, 3-picolinium, methylphenylammonium, dimethylphenylammonium) were synthesized by the reaction of mercaptoacetic acid with dimethyltin dichloride in the presence of an organic base. These complexes have been characterized by elemental analyses, IR and ¹H NMR spectroscopies. The crystal structure of [(n-Pr)₃NH][Me₂Sn(μ²-SCH₂COO)Cl] was determined by X-ray crystallography. The structure consists of an anion part, and a tri-n-propylammonium cation part as a counterion. The tin atom has a distorted cis-tbp geometry with two carbon and one sulfur atoms occupying the equatorial positions and the O atom and Cl atom occupying the axial positions. The organotin anion and its counterion are connected through a hydrogen bond between the N atom in the ammonium and the O atom of the carbonyl group with a N-O length of 2.766 Å.