C,N‐chelated organotin(IV) compounds as catalysts for transesterification and derivatization of dialkyl carbonates

The potential catalytic activity of selected C,N‐chelated organotin(IV) compounds (e.g. halides and trifluoroacetates) for derivatization of both dimethyl carbonate (DMC) and diethyl carbonate (DEC) was investigated. Some tri‐, di‐ and monoorganotin(IV) species (L^CN(n‐Bu)₂SnCl (1), L^CN(n‐Bu)₂SnCl.HCl (1a), L^CN(n‐Bu)₂SnI (2), L^CNPh₂SnCl (3), L^CNPh₂SnI (4), L^CN(n‐Bu)SnCl₂ (5), L^CNSnBr₃ (6) and [L^CNSn(OC(O)CF₃)]₂(μ‐O)(μ‐OC(O)CF₃)₂ (7)) bearing the L^CN moiety (L^CN = 2‐(N,N‐dimethylaminomethyl)phenyl‐) were assessed as catalysts for reactions of both DMC and DEC with various substituted anilines. The catalytic activities of 4 and 7 for derivatization of DMC with p‐substituted phenols were studied for comparison with the standard base K₂CO₃/Silcarbon K835 catalyst (catalyst 8). The composition of resulting reaction mixtures was monitored by multinuclear NMR spectroscopy, GC and GC‐MS techniques. In general, catalysts 1, 3 and 7 exhibited the highest catalytic activity for all reactions studied, while some of them yielded selectively carbonates, carbamates, lactam or substituted urea. Copyright © 2012 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.     

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.     

Structure of N,C,N-chelated organotin(IV) fluorides

The set of starting tri-, di- and monoorganotin(IV) halides containing N,C,N-chelating ligand (L^NCN = {1,3-[(CH₃)₂NCH₂]₂C₆H₃}⁻) has been prepared (1-5) and two compounds structurally characterized ([L^NCNPh₂Sn]⁺I₃⁻ (1c), L^NCNSnBr₃ (5)) in the solid state. These compounds were reacted with KF with 18-crown-6, NH₄F or L^CNnBu₂SnF to give derivatives containing fluorine atom(s). Triorganotin(IV) fluorides L^NCNMe₂SnF (2a) and L^NCNnBu₂SnF (3a) revealed monomeric structural arrangement with covalent Sn-F bond both in the coordinating and non-coordinating solvents, except the behaviour of 3a that was ionized in the methanol solution at low temperature. The products of fluorination of L^NCNSnPhCl₂ (4) and 5 were described by NMR in solution as the ionic hypervalent fluorostannates or the oligomeric species reacting with chloroform, methanol or moisture to zwitterionic monomeric stannate L^NCN(H)⁺SnF₄⁻ (5c), which was confirmed by XRD analysis in the solid state.     

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.     

New di- and triorganotin(IV) complexes of tripodal Schiff base ligand containing three imidazole arms: Synthesis, structural characterization, anti-inflammatory activity and thermal studies

Some new tri- and diorganotin(IV) complexes of the general formula, R₃Sn(H₂L) and R′₂Sn(HL) [where R = Me, n-Pr, n-Bu and Ph; R′ = Me, n-Bu, Ph and n-Oct; H₃L = Schiff base (abbreviated as tren(4-Me-5-ImH)₃) derived from condensation of tris(2-aminoethyl)amine (tren) and 4-methyl-5-imidazolecarboxaldehyde (4-Me-5-ImH)] have been synthesized. The coordination behaviour of Schiff base towards organotin(IV) moieties is discussed on the basis of infrared and far-infrared, ¹¹⁹Sn Mössbauer and multinuclear (¹H, ¹³C and ¹¹⁹Sn) magnetic resonance (NMR) spectroscopic studies. Thermal studies of all of the synthesized organotin(IV) complexes have been carried out using TG, DTG and DTA techniques. The residues thus obtained from pyrolysis of the studied complexes have been characterized by X-ray powder diffraction analysis and IR. The newly synthesized complexes have been tested for their anti-inflammatory activity and toxicity (LD₅₀).     

Structural study of C,N‐chelated monoorganotin(IV) halides

Three monoorganotin(IV) compounds of general formula L^CNSnX₃, where L^CN is a 2‐(dimethylaminomethyl)phenyl‐ group and X = Cl ( 1 ), Br ( 2 ) and I ( 3 ), were prepared and characterized using XRD and NMR techniques. Compound 1 reacts with moisture producing [(L^CN)₂HSnCl₂]⁺ [L^CNSnCl₄]^?. Compound 3 decomposes to (L^CN)₂SnI₂, SnI₂ and I₂ when heated. Compound 2 was reacted with NH₄F yielding an equilibrium of fluorine‐containing species. The major products were [L^CNSnF₅]^2? and [(L^CNSnF₃)₂(µ²‐F)₂]^2? (4a). When compound 2 was reacted with another fluorinating agent, L^CN(n‐Bu)₂SnF, an oligomeric product, [L^CNSnF₂(µ²‐F)₂]_n, was observed. Further addition of NH₄F led to subsequent formation of 4a. The structure of fluorinated products was investigated by ¹H, ¹⁹F and ¹¹⁹Sn NMR spectroscopy. Copyright © 2006 John Wiley & Sons, Ltd.     

Structural investigations on diorgano- and triorganotin(IV) derivatives of [meso-tetra(4-sulfonatophenyl)porphine] metal chlorides

Several new complexes of organotin(IV) moieties with MCl_n[meso-tetra(4-sulfonatophenyl)porphine], (R₂Sn)₂MCl_n[meso-tetra(4-sulfonatophenyl)-porphinate]s and (R₃Sn)₄MCl_n [meso-tetra(4-sulfonatophenyl)porphinate]s, [M = Fe(III), Mn(III): n = 1, R = Me, n-Bu; Ph; M = Sn(IV): n = 2, R = Me, n-Bu] have been synthesized and their solid state configuration investigated by infrared (IR) and Mössbauer spectroscopy, and by ¹H and ¹³C NMR in D₂O.The electron density on the metal ion coordinated inside the porphyrin ring is not influenced by the organotin(IV) moieties bonded to the oxygen atoms of the side chain sulfonatophenyl groups, as it has been inferred on the basis of Mössbauer spectroscopy and, in particular, from the invariance of the isomer shift of the Fe(III) and Sn(IV) atoms coordinated into the porphyrin square plane of the newly synthesized complexes, with respect to the same atoms in the free ligand.As far as the coordination polyhedra around the peripheral tin atoms are concerned, infrared spectra and experimental Mössbauer data would suggest octahedral and trigonal bipyramidal environments around tin, in polymeric configurations obtained, respectively, in the diorganotin derivatives through chelating or bridging sulfonate groups coordinating in the square plane, and in triorganotin(IV) complexes through bridging sulfonate oxygen atoms in axial positions.The structures of the (Me₃Sn)₄Sn(IV)Cl₂[meso-tetra(4-sulfonatophenyl)porphinate] and of the two model systems, Me₃Sn(PS)(HPS) and Me₂Sn(PS)₂ [HPS = phenylsulfonic acid], have been studied by a two layer ONIOM method, using the hybrid DFT B3LYP functional for the higher layer, including the significant tin environment. This approach allowed us to support the structural hypotheses inferred by the IR and Mössbauer spectroscopy analysis and to obtain detailed geometrical information of the tin environment in the compounds investigated.¹H and ¹³C NMR data suggested retention of the geometry around the tin(IV) atom in D₂O solution.     

Tin(IV) and organotin(IV) derivatives of novel β-diketones: Part IV. Triorganotin(IV) complexes of fluorinated 4-acyl-5-pyrazolones. Crystal structure of (1-(4-trifluoromethylphenyl)-3-methyl-4-acetylpyrazolon-5-ato)triphenyltin(IV)

The synthesis of three 1-(4-trifluoromethylphenyl)-3-methyl-4-R¹(C=O)-5-pyrazolone proligands LH (L¹H; R¹=C₆H₅: L²H; R¹=CH₃: L³H; R¹=CF₃) and their interaction with R₃Sn(IV) acceptors (R=Me, Buⁿ, Ph) are reported. When R=Me or Buⁿ, aquo (4-acylpyrazolonate)SnR₃(H₂O) derivatives are obtained and the anionic donors 4-acylpyrazolonate (L⁻) act in the O–monodentate form. These triorganotin complexes are not stable in chlorohydrocarbon solvents and decompose to R₄Sn and bis(4-acyl-5-pyrazolonate)₂SnR₂. When R=Ph, stable (4-acyl-5-pyrazolonate)SnPh₃ derivatives, both in solution and in the solid state, are obtained. The crystal structure of (1-(4-trifluoromethylphenyl)-3-methyl-4-acetylpyrazolon-5-ato)triphenyltin(IV) shows a five-coordinate tin atom in a strongly distorted cis-bipyramidal trigonal environment (axial angle=161.2(2)°) with the acylpyrazolonate donor acting as an asymmetric O₂–bidentate species (Sn–O(1)=2.081(6) Å: Sn–O(2)=2.424(5) Å). Electronic effects are responsible for the different behavior shown by these trialkyl and triphenyl derivatives.     

In vitro antitumor and antibacterial assay of organotin(IV) complexes of 2,3-methylenedioxybenzoic acid; X-ray crystal structure of [(C2H5)2Sn(C8H5O4)2]

New organotin(IV) compounds containing the carboxylate ligand 2,3-methylenedioxybenzoic acid (HL) have been synthesized with the general formula R₂SnL₂ (R = Me, Et, n-Bu, Ph and n-Oct) and R₃SnL (R = n-Bu). All compounds have been studied in the solution state by multinuclear NMR (¹H, ¹³C and ¹¹⁹Sn) by using the non-coordinating solvent and also in solid sate by FTIR, mass spectrometry and X-ray crystallography. Spectroscopic data have shown that methylenedioxy moiety does not coordinate with tin atom and the coordination site is actually -COO group, as is proved by X-ray structure determination. The solid state structure of compound (2) has been determined by X-ray crystallography which shows that the complex (2) has distorted octahedral geometry. These complexes have been evaluated in vitro against crown gall tumor and antibacterial activity. Interesting results were noticed during the bio-activity screenings, which proved their in vitro biological potential and possible use as drugs.     

Organotin(IV) triazolates: Synthesis and their spectral characterization

Some organotin(IV) triazolates of general formula R_nSn(L)_4 − n (where R = Me, n-Bu and Ph for n = 2; R = Me, n-Pr and n-Bu for n = 3 and HL = 3-amino-5-mercapto-1,2,4-triazole) have been synthesized by the reaction of R₂SnCl₂/R₃SnCl with NaL in 1:2/1:1 molar ratio. Whereas, Oct₂SnL₂ has been synthesized azeotropically by the reaction of Oct₂SnO and HL in 1:2 molar ratio. As good single crystals were not obtained, a large number of experimental techniques, viz. UV/Vis, IR, far-IR, multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR and ¹¹⁹Sn Mössbauer spectroscopic studies, were used to accomplish a definitive characterization and determination of their most probable structures. In these compounds triazole acts as a monoanionic bidentate ligand, coordinating through S_exo and N(4). The IR and ¹¹⁹Sn Mössbauer spectroscopic studies allow us to deduce a highly distorted cis-trigonal-bipyramidal structure for R₃SnL and a distorted skew trapezoidal-bipyramidal structure for R₂SnL₂, in the solid state. However, ¹H, ¹³C and ¹¹⁹Sn NMR spectral studies revealed that weak bonding between tin and N(4) is further weakened in the solution leading to pseudo-tetrahedral/tetrahedral structure.     

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.     

Synthesis,characterization, biological activities,crystal structure and DNA binding of organotin(IV) 5-chlorosalicylates

New organotin(IV) carboxylates, R₂SnL₂ (R=n-Bu: 1), R₂Sn(Cl)L (R=n-Bu: 2), and R₃SnL (R=Me: 3; n-Bu: 4; Ph: 5) have been synthesized by stirring 5-chloro-2-hydroxybenzoic acid HL with KOH and R₂SnCl₂ (R=n-Bu)/R₃SnCl (R=Me, n-Bu, Ph) in methanol at room temperature. The complexes along with ligand have been characterized by FTIR, (¹H, ¹³C) NMR, EI-MS, and single-crystal XRD crystallography. FTIR data indicated bidentate coordination of carboxylate. NMR data suggested six- or five-coordinate geometry of organotin(IV) carboxylates. Single-crystal XRD of 1 demonstrated skew-trapezoidal geometry around the tin center, with the basal plane occupied by four oxygens and the two butyl groups lying in distorted axial position. Complexes 1, 2, and 5 exhibited interaction with SS-DNA (salmon sperm) and suggests intercalating mode of binding. The complexes displayed significant antimicrobial activities against bacterial and fungal strains as compared to free ligand. The hemolytic activity of the complexes was lower compared to Triton-X 100 (positive control, 100% lysis) and higher than phosphate-buffered saline (negative control, 0% lysis). Complex 4 was the most potent inhibitor of bacterial/fungal growth.     

Synthesis and structural characterization of organotin(IV) compounds derived from the self-assembly of hydrazone Schiff base series and various alkyltin salts

Reactions of pyruvic acid hydrazone series [pyruvic acid thiophenecarbonyl hydrazone (L1), pyruvic acid 4-hydroxybenzoylhydrazone (L2), pyruvic acid salicyloylhydrazone (L3), pyruvic acid benzoylhydrazone (L4)], or salicylaldehyde hydrazone Schiff base ligand [salicylaldehyde isonicotinoylhydrazone (L5)] with different alkyltin salts result in six new organotin(IV) compounds, {(n-Bu)₂Sn[2-SC₄H₃CON₂C(CH₃)CO₂](HOC₃H₇-i)}₂ (1), [{(n-Bu)₂SnCl(O)(n-Bu)₂ Sn(O)[C₆H₄CON₂C(CH₃)CO₂]Sn(n-Bu)₂(HOCH₃)}₂]_∞ (2), {(o-ClBz)₂Sn[4-HOC₆H₄CON₂C(CH₃) CO₂] (HOC₂H₅)}₂ (3), {(n-C₈H₁₇)₂Sn[2-HOC₆H₄CON₂C(CH₃)CO₂](H₂O)}₂ (4), {(n-Bu)₂Sn[C₆H₅ CON₂C(CH₃)CO₂][HOSn(n-Bu)₃]}₂ (5), and {[(n-C₄H₉)SnCl₂]⁻[4-NHC₅H₄CON₂CH (C₆H₄O-2)]⁺ (6), which have been characterized by single crystal X-ray diffraction, elemental analysis, IR, ¹H and ¹¹⁹Sn NMR. In compounds 1, 3, 4, weak-bridged dimers are found, in which the two tin atoms are linked by a pair of monodentate bridges. Each pyruvic acid hydrazone ligand serves as an enolic tridentatic ligand. Compound 2 contains dimeric units of {Sn₆(L2)₂(n-Bu)₆(HOCH₃)₂} that are further connected by two pairs of monodentate bridges into an 1D weak-bridged polymeric chain, in which there also exists a fascinating dichlorodistannoxane ladder structure. Studies show that the bulk and steric hindrance of the alkyl groups and the coordinated solvent molecule bonding to Sn center have little effect on the geometry of the weak-bridge for compounds 1-4. A similar weak-bridged dimeric structure is also found in compound 5; in this case, however, there is no coordinated solvent molecule and the corresponding coordination site is replaced by the trialkyltin hydroxide. Compound 6 exhibits a rare 1D supermolecular chain constructed from the zwitterionic {Sn(L5)(n-Bu)Cl₂} units connected by the intermolecular N-H?Cl hydrogen bonds. The thermal stability of compound 1 was also studied.     

Diorganotin(IV) bis(O,O-alkylenedithiophosphates)

O,O-Alkylenedithiophosphates of diorganotin(IV) of the type R₂Sn[SP(S)O₂G]₂ (R = Me, Et, n-Bu, Ph; G = CH₂CMe₂CH₂, CMe₂CMe₂, CMe₂CH₂CHMe) have been synthesized by the reactions of diorganotin(IV) dichlorides with ammonium O,O-alkylenedithiophosphates or that of diorganotin(IV) oxides with O,O-alkylenedithiophosphoric acids in 1:2 molar ratio in benzene. These new complexes are white solids which are soluble in common organic solvents and are monomeric in refluxing benzene; and they have been characterized by elemental analysis and by different spectroscopic (IR, ¹H, ¹³C, ³¹P and ¹¹⁹Sn NMR) studies, on the basis of which a six coordinated octahedral structure has been suggested in solution.     

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.     

Di-n-octyltin(IV) complexes with 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acid: Syntheses and assessment of solid state structures by Sn Mössbauer and X-ray diffraction and further insight into the solution structures using electrospray ionization MS, Sn NMR and variable temperature NMR spectroscopy

Reactions of 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids (LHH′, where the aryl group is an R-substituted phenyl ring such that for L¹HH′: X = H; L²HH′: X=2′-OCH₃; L³HH′: X = 3′-CH₃; L⁴HH′: X = 4′-CH₃; L⁵HH′:X = 4′-Cl) with ⁿOct₂SnO in 2:1 and 1:1 molar ratios have been investigated. Two types of complexes, ⁿOct₂Sn(LH)₂ and {[ⁿOct₂Sn(LH)]₂O}₂, were isolated and they have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of ⁿOct₂Sn(L¹H)₂ (1), {[ⁿOct₂Sn(L²H)]₂O}₂ (3) and {[ⁿOct₂Sn(L³H)]₂O}₂(4) were determined. The mononuclear complex 1 was found to adopt a skew-trapezoidal bipyramidal arrangement around the tin atom while 3 and 4 are centrosymmetric tetranuclear bis(dicarboxylatotetrabutyldistannoxane) complexes containing a planar Sn₄O₂ core in which two μ₃-oxo O-atoms connect an Sn₂O₂ ring to two exocyclic Sn-atoms. The solution structures were confirmed by ¹¹⁹Sn NMR spectroscopy by observing one tin resonance in compound 1 and two tin resonances in {[ⁿOct₂Sn(L⁵H)]₂O}₂ (5). {[ⁿOct₂Sn(L²H)]₂O}₂ (3) and {[ⁿOct₂Sn(L³H)]₂O}₂ (4) undergo very complex exchange processes in deuteriochloroform solution, which has been confirmed by variable temperature ¹H NMR spectroscopy. The cleavage of the most labile bond in the molecule was studied by ESI mass spectrometry.     

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.     

Structural chemistry of mononuclear, tetranuclear and hexanuclear organotin(IV) carboxylates from the reaction of di-n-butyltin oxide or diphenyltin oxide with rhodanine-N-acetic acid

Three new organotin(IV) carboxylates, {[n-Bu₂Sn(O₂CC₄H₄NOS₂)]₂O}₂ (1), n-Bu₂Sn(O₂CC₄H₄NOS₂)₂ (2) and [PhSn(O)O₂CC₄H₄NOS₂]₆ · 3H₂O (3) were synthesized by the reaction of di-n-butyltin/diphenyltin oxide and rhodanine-N-acetic acid. The complexes 1-3 are characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR and X-ray crystallography diffraction analyses. The complex 1 has a tetranuclear structure based on a planar four-membered Sn₂O₂ ring, while complex 2 is a hexa-coordinated monomer. As for complex 3, it adopts the hexameric drum-shaped structure. The supramolecular structure of 1 has been found to consist of one-dimensional molecular chain built up by intermolecular non-bonded S?O interactions. The salient feature of the supramolecular structure of complex 2 is that of a one-dimensional polymer, in which intermolecular Sn?O, S?O and S?S interactions are recognized.     

Diorganotin(IV) dithiocarbamate complexes as chromogenic sensors of anion binding

One dinuclear chlorodiphenyltin (IV) dithiocarbamate complex (1) and four mononuclear complexes of general formula Ph₂Sn(S₂CNR)Cl (2, 3, 5, and 6) have been synthesized and characterized both in solid-state and solution. X-ray structures for complexes 1, 3 and 6 demonstrated a five-coordination geometry around of tin atoms, in which dithiocarbamate ligand chelates asymmetrically the metal center. As shown by ¹¹⁹Sn NMR spectroscopy, five-coordination geometry observed in the solid-state remains in solution. The stability of these chlorodiphenyltin(IV) dithiocarbamate complexes in the presence of biologically relevant anions such as acetate, dicarboxylates of general formula ^?OOC-(CH₂)_n-COO^? (n = 2–8), dihydrogenphosphate, hydrogensulfate, and halides has been examined in acetonitrile solutions. For all of these organotin(IV) complexes the displacement of the coordinated ligands (i.e., chloride and dithiocarbamate) from the organotin(IV) moiety occurred in the presence of monoanions like acetate, dihydrogenphosphate, hydrogensulfate and fluoride. A stepwise mechanism for ligand exchange is proposed based on UV–Vis, ¹H, ¹³C and ¹¹⁹Sn spectroscopic data, as well as mass spectrometry. From UV–Vis titration experiments it was found that dicarboxylates with small spacers like malonate and succinate, acted differently in the exchange of the dithiocarbamate group in comparison to other monoanionic O donor ligands or dicarboxylates with longer chains, perhaps by following an intramolecular displacement of the coordinated ligand.The lability of these organotin(IV) dithiocarbamate compounds in solution hampers their use as stably host for anions, however, by taking advantage of the intrinsic chromogenic properties of free dithiocarbamate anions, or by attaching dithiocarbamate groups to well-known fluorescent moieties such as antracene, these complexes can sense the presence of O-donor anions at very low concentrations by displacement of the metal-coordinated dithiocarbamate.