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The authors are grateful to the Tunisian Ministry of High Education and Scientific Research and Technology for financial support of this research Bisphosphonates of the types X(P(O)(OEt)2)2 (X = CH2=C (1a), CNCH2CH (1b) and PhCH2NCH2CH (1c)) react with SnCl4 in anhydrous dichloromethane to produce the new tin(IV) adducts [SnCl4(1a)] (2a), [SnCl4(1b)] (2b) and [SnCl4(1c)] (2c) in 72-80% yields. These complexes were characterized using IR, multinuclear (1H, 13C, 31P, 119Sn) NMR spectroscopy, elemental analysis, and in one case by single crystal X-ray diffraction. The NMR data show that the bisphosphonate ligands are coordinated to the tin center in a bidentate fashion forming cis octahedral tin complexes. Furthermore, the X-ray structure of complex 2b reveals that the bisphosphonate ligand is coordinated in a bidentate manner to the metal center in a distorted octahedral arrangement with Sn-O-P bond angles in the range 135.95(16)–137.99(18)°. The P=O and Sn-O bond lengths of 1.495(3)-1.497(3) and 2.134(3)-2.146(2) Å, respectively are in the order expected for phosphonate tin(IV) complexes. The results are discussed and compared with closely related analogues. Postprint

The surfactant sodium bis(2-ethylhexyl) sulfosuccinate based tin(IV) phosphate (AOT-SnP) fibrous ion exchanger has been synthesized and characterized by using different physico-chemical methods. The characterization of the exchanger was performed by using infrared (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and elemental analysis. The ion exchange property was studied by determining the ion exchange capacity, elution and concentration behavior of the cation exchanger. The thermal behavior of exchanger was studied by performing ion exchange capacity at different temperatures. Adsorption studies on the synthesized material showed that it is highly selective for Cd2+, Zn2+and Hg2+ ions. Therefore, the separation of Cd2+, Zn2+and Hg2+ ions from the synthetic waste water has been performed on its column and observed to be quite effective in presence of acid, alkali, alkaline earth and other transition metals.

The stereochemistry of four octahedral complexes SnCl 4 ·2(O)PCl(NR 2 ) 2 (R = Me ( 1 ); R = Et ( 2 )) and SnCl 4 ·2(O)PCl 2 NR 2 (R = Me ( 3 ); R = Et ( 4 )) was studied by both multinuclear ( 1 H, 31 P and 119 Sn) NMR spectroscopy in solution and density functional theory (DFT) calculation. The NMR data suggest the presence in dichloromethane solutions of a mixture of cis and trans isomers for 1 and 2 , whereas only the cis isomer is observed for 3 and 4 . Moreover, the latter complexes showed partial ligand dissociation in solution. The assignment of the cis and trans isomers was based on the NMR chemical shifts and particularly on the magnitude of the 2 J ( 31 P– 119 Sn) coupling constant obtained in both solution NMR and DFT studies. In addition, the stereochemistry observed was shown to be highly dependent on the steric hinderance and/or the Lewis basicity of the phosphine oxide ligand. DFT/B3LYP calculations which compared favourably with the experimental data provided further insight into the coordination at the tin atom. The results obtained for both complexes are compared with those of the hexamethylphosphoramide complex.

The reaction of meso -tetraarylporphyrins (H 2 T(X)PP) with SnCl 4 affords green intermediate sitting-atop (i-SAT) complexes, [(H 2 T(X)PP)SnCl 4 ]. UV–Vis, 1 H NMR and 13 C NMR spectral data show that the porphyrin core of the complexes is distorted, thus two nitrogen atoms of the pyrrolenine groups on one side of the porphyrin plane act as electron donors to the tin center of SnCl 4 . The intermediate sitting-atop (i-SAT) complex is formed each time during the incorporation of the metal center, where in the intermediate state the pyrrolic protons still remain on the porphyrin.

The two octahedral complexes SnCl4 · 2(O)P(NR2)2OCH2CF3 (R = Me (1) or Et (2)) have been prepared from SnCl4 and the ligands (R2N)2P(O)OCH2CF3 in chloroform solution. Both adducts have been characterised by (31P and 119Sn) NMR, IR spectroscopy and elemental analysis. The NMR data show that the complexes exist as mixtures of cis and trans isomers in solution with the latter isomer being the predominant species. The structure of 1 has been determined by X-ray crystallography. Accordingly, the structure is centrosymmetric and the two ligands are bound trans to each other in the octahedral tin complex. DFT/B3LYP calculations show that trans configuration does indeed lead to the lowest energy species. Comparison of the structural, NMR and theoretical data of both complexes with those related to SnCl4 · 2L (L = (Me2N)3P(O) and (Me2N)2P(O)F) further supports the important effects of the nature of the substituents in the ligand on the stereochemistry of the complex formed.

Two octahedral complexes of the general formula SnCl 4 · 2(O)PF 2 NR 2 (R = Me ( 1 ) or Et ( 2 )) have been synthesised from SnCl 4 and the ligand R 2 NP(O)F 2 in anhydrous CHCl 3 . The new adducts have been characterised by multinuclear ( 119 Sn, 31 P, 19 F and 1 H) NMR, IR spectroscopy and elemental analysis. When compared with previously described hexamethylphosphoramide (HMPA) and trimethylphosphate (TMPA) analogues, the NMR data of the two complexes prepared suggest the presence of only the cis isomer in solution. Steric factors and the Lewis basicity of the ligand may explain the stereochemistry observed. Low temperature 31 P and 119 Sn NMR spectra show that the compounds partially dissociate in dichloromethane. Additionally, DFT/B3LYP calculations on complex 1 and its ligand have been carried out to support the interpretations of NMR data.

The compounds [SnCl4(L)n] (where L is pyridine (py), 4-methylpyridine (γ-pico), 3-methylpyridine (β-pico), piperidine (pipd), morpholine (morph), piperazine (pipz), 3-cyanopyridine (3-cyanopy), 4-cyanopyridine (4-cyanopy), quinoline (quin) or 2,2′-bipyridine (bipy) and n=2, 1 or 3/2) were synthesized and characterized by elemental analysis, melting points, thermal studies and IR spectroscopy. The enthalpies of dissolution of adducts, tin(IV) chloride and ligands in 1,2-dichloroethane or 25% (v/v) aqueous HCl 1.2 M in methanol were measured and, by using thermochemical cycles, the following thermochemical parameters for the adducts have been determined: the standard enthalpies for the Lewis acid/base reaction (ΔrH°), the standard enthalpies of formation (ΔfH°), the standard enthalpies of decomposition (ΔDH°), the lattice standard enthalpies (ΔMH°) and the standard enthalpies for the Lewis acid/base reaction in the gaseous phase (ΔrH°). The mean standard enthalpies of the tin–nitrogen bonds ( D ( Sn – N ) ) have been estimated. Based on these last values, the basicity orders: pipd>morph>γ-pico=β-pico>py>4-cyanopy>3-cyanopy and pipz>quin are obtained.

Tin(IV) chloride selectively promotes the nucleophilic attack of methyl acetoacetate to the cyano instead of the olefinic carbon atom of α,β-unsaturated nitriles to give enaminoketoesters. In the presence of an excess of ketoester a second C–C bond formation occurs followed by cyclisation affording substituted pyridines in a selective cascade sequence.

The reaction of benzil with phenol at 180°C in the presence of SnCl4·5H2O produces a benzofuran, a benzofuranol, a benzodifuran, and a benzofuranone. Anhydrous tin(IV) chloride also gives a benzofuranofuranone. Other phenols and their methyl ethers yield related products. The good yields of the benzo- and naphtho-furanones make the method an attractive alternative to the benzilic acid route to such compounds.

2,3,5-Tri- O -benzoyl-β- d -ribofuranosyl cyanide reacts with methyl acetoacetate and diethyl malonate in the presence of stoichiometric amounts of SnCl 4 to give a β- d -ribofuranosyl-enaminoketoester and a β- d -ribofuranosyl-enaminodiester, respectively. The β- d -ribofuranosyl-enaminoketoester was debenzoylated, treated with 2,2-dimethoxypropane and tert -butyl-dimethylsilyl chloride to give the methyl 3-amino-3-(5′- O - tert -butyldimethylsilyl-2′,3′- O -isopropylidene-β- d -ribofuranosyl)-2-acetyl propanoate obtained in good yield together with small amounts of its α-anomer. The reactions of the β-anomer with hydrazine, methyl- and phenylhydrazine, carried out under controlled experimental conditions, afforded the pyrazole C-nucleosides in good yields as β-anomers.

The compounds [SnCl 4 (L) 2 ] (where L is urea (u), 1,1-dimethylurea (1,1-dmu), 1,3-dimethylurea (1,3-dmu), tetramethylurea (tmu), thiourea (tu), tetramethylthiourea (tmtu) or 1-allyl-2-thiourea (atu)) were synthesized and characterized by melting points, elemental analysis, thermal studies and IR spectroscopy. The enthalpies of dissolution of the adducts, tin(IV) chloride and ligands in methanol were measured and by using thermochemical cycles the following thermochemical parameters for the adducts, have been determined: the standard enthalpies for the Lewis acid/base reactions (Δ r H θ ), the standard enthalpies of formation (Δ f H θ ), the standard enthalpies of decomposition (Δ D H θ ), the lattice standard enthalpies (Δ M H θ ) and the standard enthalpies of the Lewis acid/base reactions in the gaseous phase (Δ r H θ (g)). The mean standard enthalpies of the tin-oxygen (D(Sn–O)) and tin-sulphur (D(Sn–S)) bonds have been estimated.

Full crystal structures are reported for the tris(o-methoxyphenyl)tin compounds, (o-CH3OC6H4)3SnX [X=Cl (A), F (B)] and [(o-CH3OC6H4)3Sn]2O (C), together with both solid-state and solution (CDCl3) 119Sn NMR data for B and C as well as (Mes)3SnF and [(o-Tol)3Sn]2O. Compound B like A is monomeric with a similar but not identical arrangement of aryl groups around the tin while NMR data indicate that B has almost the same geometry in solution as in the solid state. The anomalously lower frequency δ(119Sn) value for B is consistent with the more ionic character of the SnF bond compared with other SnX (X=Cl, Br, I) bonds. Compound C is the first (Ar3Sn)2O with an SnOSn bond angle between 140 and 180°. The comparison of solid-state with solution 2J(119Sn,119Sn) values for C and [(o-Tol)3Sn]2O suggests that the solid state favours structures having larger SnOSn angles. Reacting C with water gives (o-CH3OC6H4)3SnOH only in solution, identified by its 13C and 119Sn NMR spectra.

Using tin(IV) chloride, O -glycosylation reactions were performed on peracylated D-arabinofuranose, d -galactofuranose and l -rhamnofuranose as well as 1-bromo- d -arabinofuranoses at room temperature in good anomeric purities and yields. In these circumstances, this coupling method has certain advantages over standard glycosylation reactions, such as the Koenigs-Knorr methods which use the 1-halosugar (synthesized from the 1-acyl derivative) and toxic mercury salts as the coupling agent.

Several new tetra-aryltin compounds, Ar4Sn (Ar = 3,5-(CH3)2C6H3, 3,5-Z2C6H3, and m-ZC6H4 (Z = F,Cl] and Ar3SnX [X = Cl, Br, I: Ar = 3,5-(CH3)2C6H3, m- and o-CH3OC6H4; X = Br; Ar = m-ZC6H4 (Z = F, Cl)] have been synthesized by literature methods and complete solution NMR data (119Sn, 13C) are reported for these and other meta- and ortho-substituted aryltins. Meta-substituents appear to exert electronic effects on chemical shifts and coupling constants, but for ortho-substituents steric effects appear to predominate. Crystal data show that meta-substituted Ar3SnX have trigonal unit cells in contrast to the monoclinic unit cells adapted by para- and ortho-substituted Ar3SnX. Complete crystal structures are reported for (m-CH3C6H4)3SnCl: R3. a = 14.9262(15), c = 7.3482(12) A , Z = 3 and (3,5-(CH3)2C6H3)3SnCl: R3c, a = 15.119(8), c = 15.593(4) A , Z = 6. In both cases, all molecules have trigonal symmetry, the first such examples to be reported.

Following observations on remote asymmetric induction using allylstannanes, 5-benzyloxy-4-methylpent-2-enylsilanes are also found to react with aldehydes with modest levels of 1,5-induction after treatment with tin(IV) chloride. Transmetallation to give intermediate allyltin trihalides may be involved.

As determined by single crystal X-ray crystallography, SnCl 4 ·2H 2 O and SnCl 4 ·3H 2 O have a molecular structure with cis -[SnCl 4 (H 2 O) 2 ] units linked to each other by a system of hydrogen bonds.

The reaction of 5-fluorouracil with the seven-membered acetals 1a-g in the presence of tin (IV) chloride, trimethylchlorosilane and hexamethyldisilazane at room temperature gives 1-{[3-(2-hydroxyethylhetero)-1-alkoxy]alkyl}-5-fluorouracils 2a-f and 1-{[2-(3-hydroxypropoxy)-1-isopropoxy]ethyl}-5-fluorouracil 2g in 31–86% yields. The presence of an heteroatom on the 1-position of the cycloacetal and the use of tin (IV) chloride, capable of a 1,4-chelation, seem to impose their influence in the regiospecific ring opening of 1a-g. The conformational analyses carried out on 2b and (1R,3R)-2e and (1R,3S)-2e clearly indicate that the N1(sp2)-C1-C2-C3 moiety tends to fold in a gauche conformation. The antitumour activities of compounds 2b-g were assessed against HEp human cells showing that 2c is 4-fold more active than 5-FU. The drugs studied do not show any clear toxicity in comparison with the toxic effect of 5-FU.

Ortho-aminobenzonitriles 1 react with β-ketoesters and alkyl malonates, in the presence of stoichiometric amounts of tin(IV) chloride, to give 4-aminoquinolines 2 and 4-amino-2-quinolones 3 respectively. Similarly β-enaminonitriles 7 afford 4-aminopyridines 8 and 4-amino-2-pyridones 9.

2-Propenyl tin species, prepared from 3-halopropenes or 2-propenyl mesylate with tin(IV) chloride and tetrabutylammonium iodide in dichloromethane, causes nucleophilic addition to aldehydes to produce the corresponding homoallylic alcohols.

The cross-coupling reaction of allylstannanes with allylsilanes selectively proceeded in the presence of tin(IV) chloride to give 1,5-dienes. It was found that the substitution of a phenylthio group at γ-position remarkably increased the reactivity of allylstannanes.

Monomeric non-cyclic and dimeric cyclic bis(amino)stannylenes react with tin(IV) chloride to give the corresponding bis(amino)tin dichlorides ( 1, 2 ) in essentially quantitative yield. By monitoring the exchange reaction between tin(IV) chloride and tetrakis(diethylamino)tin using 119 Sn NMR at low temperature, two intermediates ( 4, 5 ) were identified as binuclear complexes in which the tin atoms are bridged by two amino groups and one chloro ligand. The equilibrated 1:1 reaction mixture finally contains mainly bis(diethylamino)tin dichloride ( 3 ). The reaction between N,N ′-di-tert-butyl-1,3-diaminopropane/triethylamine (1:2) and SnCl 4 affords the cyclic bis(amino)tin dichloride ( 6 ) via elimination of HCl. The compounds 1–6 were characterized in solution by 1 H, 13 C, 29 Si and 119 Sn NMR. The solid state 119 Sn CP/MAS NMR spectrum of compound 6 proves that its monomeric character is retained also in the crystalline state.

119Sn NMR spectra were used to investigate the aquohalostannate(IV) complexes formed by SnCl4 and SnBr4 in aqueous and halogen acid solutions. Characteristic chemical shifts were assigned to the complex cations [SnX(H2O)5]3+, [SnX2(H2O)4]2+ and [SnX3(H2O)3]+, [SnX4(H2O)2], and the complex anions [SnX5(H2O)]− and [SnX6]2− (where X = Cl or Br); including the pairs of cis/trans or fac/mer isomers. The CPMAS spectra of crystalline solids containing [SnCl6]2− and cis- or trans-[SnCl4(H2O)2] assisted these assignments. The NMR data yielded quantitative estimates of the amounts of the various species in solution as a function of the tin concentration from 0.1 mol dm−3, where the hydrated stannic ion, Sn4+ (aq), is predominant, to near saturation where auto-complexing results in complex anion formation. Soluble hydrolysis products for which OH-bridged structures are proposed were detected in solutions without added HCl or HBr and increase in amount when NaOH is introduced. Solutions containing excess NaOH reveal [Sn(OH)6]2− which has a chemical shift of — 590 ppm and exhibits the Raman frequencies: 552 (v1), 425 (v2), 290 cm−1 (v5), appropriate for octahedral (Oh) symmetry. The 119Sn NMR spectra of tin(IV) mixed halide aqueous solutions consisted of signals ranging from — 600 ppm (H2O and Cl− ligands) to —2000 ppm (Br− ligands), due to the series of species represented by SnClxBry(H2O)z (where x+y+z = 6), and can be interpreted by relating the chemical shift of the tin nucleus to the sum of ligand electronegativities in a given complex. The solvent extraction of tin halides from aqueous acid solution by diethyl ether or isobutyl methyl ketone has been investigated and tin(IV) shown to be extracted in the form of both molecular [SnX4(H2O)2] and ion-pair H+(aq)[SnX5(H2O)]− complexes. These species can also be generated in solution by adding small amounts of water to [SnX6]2− in acetone. Conjoint use of NMR and Raman spectra enables the major species in these systems to be determined and allows the v(SnX) symmetric stretching frequencies to be identified and assigned.

β-Ketoesters and β-diesters react with β-enaminonitriles in the presence of stoichiometric amounts of tin (IV) chloride to give 4-aminopyridines and pyridones while they react with aromatic orthoaminonitriles to give 4-aminoquinolines and quinolones.

Treatment of (S)-4-benzyloxypent-(2E)-2-enyl(tributyl)stannane (3) with tin (IV) chloride at −78 °C, followed by the addition of an aldehyde, gives 1,5-diol derivatives (6) with excellent 1,5-diastereoselectivity.

Aziridine-2-carboxylates were prepared from the reaction of hexahydro-1,3,5-triazines with alkyldiazoacetates in the presence of Lewis acid catalyst in high yield.

Coordination complexes of nitrosobenzene with tin and titanium tetrachlorides have been prepared and subjected to solid-state 13 C NMR spectroscopy. The absence of resonances above 160 ppm characteristic of C NO and the presence of resonances of quaternary carbons in the range characteristic of C N 2 O 2  C suggests that the cis -dimer of nitrosobenzene is acting as a bidentate donor.

Complexes of eleven substituted pyridine N-oxide donors with stannic chloride in acetonitrile solution were investigated ultizing IR spectroscopy. Two distinct types of behaviour were noted: (1) Pyridine N-oxide donors containing electron releasing substituents generally form strong complexes with SnCl 4 and exhibit maxima in continuous variation plots at a 2:1 ligand-to-metal ratio. Little or no free ligand is detected in these solutions until this ratio is exceeded. Ligands exhibiting this behaviour include the 2-methyl-, 3-methyl-, 4-methyl-, 4-methoxy- and 4-phenylpyridine N-oxides. (2) Pyridine N-oxide donors containing electron neutral to electron with-drawing substituents generally form weaker complexes with SnCl 4 aM exhibit maxima in continuous variation plots at a 1:1 ligand-to-metal ratio. Free ligand is evident in these solutions even at ligand-to-metal ratios as low as 1:3. Formation plots for these complexes indicate the possibility that 1: 2 and 1:1 ligand to metal complexes exist in the concentration ranges studied. Ligands exhibiting this behaviour include the 4-chloro-, 4-nitro-, 3 and 4-acetyl-pyridine N-oxides and 2-pyridine methanol N-oxide. The complex of 2,6-1utidine N-oxide with SnCl 4 exhibits behaviour characteristic of the 1:1 complexes even though the substituents are electron releasing. This ligand contains the most sterically crowded N-O group in the series, however, and steric factors are invoked to explain this behavior. These results are rationalized in terms of an equilibrium model which includes the postulated existence of oxygen bridged dimers comprising a dominant species in solutions containing the 1:1 complexes. Some supporting 1 H NMR and polarographic data are also presented and discussed.

Twenty three tin(IV) tetrahalide adducts with various monodentate ligands, cis - and trans - L 2 ·SnX 4 , were studied by IR and Raman spectroscopy at room temperature and above. The observed SnX stretching frequencies as well as the structure, are correlated with the donor number of the ligands. In some cases the basicity or the bulkiness of the ligand are not the prevalent factors in determining the structure of the complex.

The reaction of caesium trichlorostannate(II) with 7,7,8,8-tetracyanoquinodimethane affords two products, the 1:1 adduct, CsSnCl3·TCNQ, and the complex SnCl2·(TCNQ)2· 1 2 thf, whilst with tetramethylammonium trichlorostannate, three complexes, Me4NSnCl3·TCNQ, Me4NSn(TCNQ)3, and (Me4NSnCl3)·TCNQ, have been isolated. Tin(IV) chloride reacts with Δ2,2′-bis(5-methyl-1,3-benzodithiolidene) and Δ2,2′-bis(1,3-diphenylinidazolidene) to afford complexes of composition, (SnCl4)3·(TTF)2·(C6H6) 3 2 and SnCl4·(TNFPh) 1 2 , respectively. The structures of the complexes are discussed on the basis of infrared and tin-119 Mossbauer data.

The reaction between SnCl 4 and R 3−n SiH n+1 (n = 0−2) have been investigated [R = CH 3 , CH = CH 2 , CH 2 CHCH 2 , CCH, CCCF 3 , C 5 H 5 , C 6 H 5 , or Si(CH 3 ) 3 ]; the reaction with silacyclopent-3-ene was also investigated. All the reactions led to monochlorination at silicon without breaking the SiC and/or SiSi bonds except in some allylsilanes, and spectroscopic parameters for the new compounds CH 2 CHCHCH 2 Si HCl, CHCSiH 2 Cl, CF 3 CCSiH 2 Cl, (CH 3 ) 3 SiSiH 2 Cl, and (CH 3 ) 3 SiSiHCl 2 , all prepared by this route, are reported. For the disilanes, 29 Si and 13 C chemical shifts were measured by heteronuclear double resonance.

Tin(IV) chloride derivatives of nickel(II) aldoximates have been obtained by reacting tin(IV) chloride with nickel(II) aldoximates in benzene. All the complexes are coloured solids and appear to be non-electrolytes in DMF. Elemental analyses agree with 1:1 stoichiometry. Magnetic, electronic and far i.r. spectral data suggest that the nickel(II) has changed its configuration from dsp2 square-planar to sp3d2 octahedral one as a result of reaction with the tin(IV) chloride. Tin(IV), also exhibits 6-coordination in these complexes.

1:2-complexes of tin (IV) chloride with anthranilic and methyl anthranilic acids, and 1:1-complexes with meta- and para-aminobenzoic acids have been prepared by direct interaction in suitable organic solvents. The former are molecular addition compounds while the latter are ionic complexes. Negative shifts of ν(NH) and positive shifts of ν(CO) indicate nitrogen-metal bonding in all these complexes.

An adduct of Tin(IV) trichloride (2-chloroethoxide) (A′) with 2-chloroethylalcohol(A) has been prepared. Complexes of A′ with amide, dimethylurea, dimethylsulphoxide, primary, secondary and tertiary amines and α,α′-dipyridyl have been prepared. I.R. spectra of the complexes in 4000-250 cm−1 spectral region have been examined to throw some light on their structure.

The coulometrie method of electrogenerated tin II ion using the platinum electrode as a generating cathode has been investigated. The electrolytic solution comprising 3 M potassium chloride and 0·3 M tin IV chloride has been found to be satisfactory for the determination of cerium IV ion, iodine and bromine with an error of only a few percent provided suitable conditions are employed.

In a layer compound of graphite, C54SnCl6, the existence of an octahedral SnCl62− anion has been established by means of 35Cl nuclear quadrupole resonance spectra.