Five-coordinate Tin Atoms Research Articles

Synthesis and structural characterization of diorganotin(IV) complexes with heteroditopic pyridyl-ONO′-ligands

A series of eight novel diorganotin(IV) complexes with heteroditopic pyridyl-ONO′-ligands were prepared viz., [Me2Sn(L1)]2⋅2(H2O) (1), [n-Bu2Sn(L1)]2 (2), [Ph2Sn(L1)] (3), [Me2Sn(L2)]2⋅2(H2L2) (4), [n-Bu2Sn(L2)]2 (5), [Ph2Sn(L2)]⋅0.5(C6H6) (6), [Me2Sn(L3)]2 (7) and [n-Bu2Sn(L3)]2 (8) and structurally characterized. Irrespective of the type of diazo L ligand, the dimethyl- and di-n-butyltin(IV) compounds are dinuclear species with an inversion center in the middle of the {Sn2O2} cores affording metals with coordination number six. The mononuclear compounds 3 and 6, with the bulky phenyl ligands, present the tin cations with highly distorted square pyramid geometries. The detection of a conformation in the (Ln)2- ligand in the solid state structures of 3, 4 and 8 which is different from the one in the remaining compounds suggests that the packing of the molecules conceivably have a greater influence than the imine substituents or the metal co-ligands. The solution 1H and 13C NMR of compounds 4–6 displayed an anisochronous behavior of dimethyl-, di-n-butyl- and diphenyltin parts while those of compounds 1–3 are isochronous. The 119Sn NMR chemical shift displacements of all the compounds are indicative of five-coordinate tin atoms, thus revealing dissociation in solution of the dinuclear 1, 2, 4, 5, 7 and 8 complexes.

Synthesis, characterization, crystal structures and supramolecular features of bicycloazastannoxides derived from Schiff bases with L-tyrosine

Six new bicycloazastannoxides of compositions [Me2Sn(L1H)] (1), [nBu2Sn(L1H)] (2), [Ph2Sn(L1H)] (3), [Bz2Sn(L1H)] (4), [Me2Sn(L2H)(MeOH)]·MeOH (5) and [Ph2Sn(L3H)] (6), where L1H = 2-((E)-((Z)-4-hydroxypent-3-en-2-ylidene)amino)-3-(4-hydroxyphenyl)propanoate, L2H = (E)-2-((2-hydroxybenzylidene)amino)-3-(4-hydroxyphenyl)propanoate and L3H = (E)-3-(4-hydroxyphenyl)-2-((1-(2-hydroxyphenyl)ethylidene)amino)propanoate, were synthesized and spectroscopically characterized. The 1H and 13C NMR spectra of compounds 1–6 displayed two sets of signals for Sn-R2 (R = Me, nBu, Ph and Bz) indicating a diastereotopic environment according to the asymmetric nature of the ligand. The 119Sn NMR data of the compounds in CDCl3 indicate five-coordinate tin atoms, showing that the bicycloazastannoxide assemblies remain intact as observed in the solid-state structures. The crystal structures of 1–6 revealed discrete molecular structures in all cases with distorted trigonal-bipyramidal geometries for 1–4 and 6, and a strongly distorted six-fold coordination for 5 due to association of a MeOH solvent molecule. At the supramolecular level, the molecular structures in 1–4 and 6 are linked either through double-bridged O-H⋯O/C-H⋯O synthons (1 and 6) or single O-H⋯O hydrogen bonds (2–4). The resulting 1D helical strands exhibit varying Sn⋯Sn distances due to the different molecular conformations. The molecules in 5 associate to dimers through two Sn⋯O and O-H⋯O interactions, which are further connected via O-H⋯O hydrogen bonds to give 1D strands containing 22-membered macrocycles.

Tributyltin(IV) complexes with amino acid-derived Schiff bases: X-ray and solution structures

Four novel tributyltin(IV) complexes of formulae [SnBu3(balabrsalH)] (1), [SnBu3(bphalabrsalH)] (2), [SnBu3(bababrsalH)] (3), and [SnBu3(gababrsalH)] (4), were obtained from the reaction of hexabutyldistannoxane with four amino acid-derived Schiff bases. Complexes were characterized by elemental analysis, FT-IR and NMR (1H, 13C and 119Sn) spectroscopy; complexes 1–3 were characterized by single crystal X-ray diffraction studies, revealing a five-coordinated tin(IV) atom with the three organic groups occupying the equatorial plane and two oxygen atoms in the apical positions, leading to a one-dimensional polymeric chain. Based on 119Sn NMR chemical shifts and nJ(119Sn13C) (n=1–3) coupling constants it is concluded that the solid-state structures are not maintained, in accordance with the disruption of the polymer upon dissolution.

Synthesis and Structural Characterization of Three New Tetraorganodistannoxanes

An efficient method was developed for the preparation of three tetraorganodistannoxane complexes, (C2H5)8Sn4Cl2(CH3O)2O2 (1), (CH3)8Sn4(C3H4N3S)2(CH3O)2O2 (2) and (C4H9)8Sn4(C3H4N3S)2(CH3O)2O2 (3). All prepared complexes were characterized by infrared, 1H, 13C and 119Sn NMR spectroscopes and elemental analysis. The molecular structure of a representative complex (1) was determined by single-crystal X-ray diffraction. Results showed that 1 is a tetranuclear, centrosymmetric dimeric, and contains two endo-cyclic five-coordinated tin atoms and two exo-cyclic five-coordinated tin atoms. Compound 1 lies about a center of inversion and the tetranuclear molecule features a three-ring-staircase Sn4O4 core. The asymmetric unit of 1 contains two independent Sn(IV) atoms and a 2D infinite rigid chain structure forms via C–H···Cl interactions between tetranuclear units.

Synthesis and structural studies of diorganotin(IV) compounds derived from (E)-3-hydroxy-2-((2-hydroxybenzylidene)amino)propanoate and (E)-3-hydroxy-2-((1-(2-hydroxyphenyl)ethylidene)amino)propanoate

Five new diorganotin(IV) compounds were prepared by reacting diorganotin dichlorides R2SnCl2 (R = Me, nBu and Ph) with sodium salts of the tridentate NO2 ligands (E)-3-hydroxy-2-((2-hydroxybenzylidene)amino)propanoic acid (L1H2Na) and (E)-3-hydroxy-2-((1-(2-hydroxyphenyl)ethylidene)amino)propanoic acid (L2H2Na). The molecular structures of the resulting diorganotin (IV) compounds have been established by elemental analysis and a combination of IR and NMR (1H, 13C, 119Sn) spectroscopy. In all cases, the 119Sn NMR chemical shifts were indicative of five-coordinate tin atoms in solution. However, investigation of compounds [Me2SnL1H]·H2O (1), [Ph2SnL1H]·2C6H6 (3), [Me2SnL2H]·CHCl3 (4) and [Ph2SnL2H] (5) by single-crystal X-ray diffraction revealed that only compound 3 has a distorted trigonal–bipyramidal geometry in the solid state. For compounds 1, 4 and 5 the coordination geometries are distorted octahedral, either due to intermolecular association through Sn⋯O interactions (1) or coordination through the oxygen atom from the pendant CH2OH group (4 and 5). At the supramolecular level, the molecular structures are linked through O–H⋯O hydrogen bonds to give discrete dimeric assemblies (4), 1D chains (3, 5) and 2D hydrogen bonded layers (1).

Synthesis, crystal structure and biological activities of two novel organotin(IV) complexes constructed from 12-(4-methylbenzoyl)-9,10-dihydro-9,l0-ethanoanthracene-11-carboxylic acid

Two complexes: [( n-Bu 2Sn) 4(L) 2O 2(OC 2H 5) 2] ( 1) and [(C 6H 5) 3Sn(L)] ( 2) (where, HL is 12-(4-methylbenzoyl)-9,10-dihydro-9,10-ethanoanthracene-11-carboxylic acid) have been prepared and structurally characterized by means of elemental analysis and vibrational, 1H NMR and FT-IR spectroscopies. The crystal structures of 1 and 2 have been determined by X-ray crystallography. Three distannoxane rings are present to the centrosymmetric dimeric tetraorganodistannoxane by virtue of μ 3-oxo form the central R 4Sn 2O 2 core with a planar Sn 2O 2 ring, resulting in a ladder type structural motif in the molecular structure of 1, and five-coordinated tin atoms are present in the distannoxane dimer. While the molecular of 2 adopts a monomeric distorted tetrahedral configuration with the carboxylate ligand coordinating in a monodentate mode. Both 1 and 2 exhibited good antibacterial and antitumour activities and have a potential to be used as drugs.

Tris(2-cyanoethyl)tin(IV) bromide and tris(2-cyanoethyl)tin(IV) iodide, their structure, properties and reactions with adenosine, AMP and ATP

Complexes [Sn(CH 2CH 2CN) 3I] ( 1) and [SnBr(CH 2CH 2CN) 3] ( 2) have been obtained by the oxidation reactions of hexakis(2-cyanoethyl)ditin(III) by means of iodine and bromine. The complexes have been characterized by NMR and IR spectroscopy methods and X-ray crystallography. Both compounds consist of zigzag single-strand chains with a bridging 2-cyanoethyl ligand coordinating via the CH 2 group and N atom. The tin atoms are in a distorted trigonal bipyramidal environment with bromo or iodo ligands and a nitrogen atom occupying the axial coordination sites. The Sn(1)–N(3i) distances in complexes 1 and 2 are considerably longer than the tin-equatorial ligand bonds. The molecular and electronic structures and IR spectra of [SnBr(CH 2CH 2CN) 3] mononuclear and [SnBr(CH 2CH 2CN) 3] 2 dinuclear fragments of the complex have been studied by the DFT B3LYP method. The calculated interatomic distances for the entity containing a five-coordinate tin atom agree well with those found crystallographically. The compounds in water solutions form trigonal bipyramidal complexes containing aqua and hydroxo axial ligands. The interaction of these complexes with adenosine, 5′-adenosine monophosphate and 5′-adenosine triphosphate has been investigated.

Self-assembly of triorganotin(IV) or diorganotin(IV) moieties and 2-methylpyrazine-5-acid: Syntheses, characterizations and crystal structures of monomeric, polymeric or tetranuclear macrocyclic compounds

A series of diorganotin(IV) and triorganotin(IV) compounds of the type [R 2Sn(pca) 2ClSnR 3] 2 (R PhCH 2 1, 2- ClC 6H 4CH 2 2, 2- FC 6H 4CH 2 3, 4- FC 6H 4CH 2 4, 4- CNC 6H 4CH 2 5, 4- ClC 6H 4CH 2 6, 2,4- Cl 2C 6H 3CH 2 7; Hpca 2-methylpyrazine-5-acid), [( n Bu) 3Sn(pca)] ∞ 8, [(CH 3) 2Cl 2Sn(pca)Sn(CH 3) 2(pca)] ∞ 9, {[( n Bu) 2Sn(pca)] 2O} 2 10 and {[Ph 2Sn(pca)] 3O 2[Ph 2Sn(OCH 3)]} 11 have been obtained by reactions of 2-methylpyrazine-5-acid with triorganotin(IV) chloride, diorganotin(IV) dichloride, and diorganotin(IV) oxide. All compounds were characterized by elemental, IR, and NMR spectra analyses. The crystal structure of compounds 1, 8– 11 were determined by X-ray single crystal diffraction, which revealed that compound 1 was tetranuclear macrocyclic structures with seven-coordinate and five-coordinate tin atoms, compounds 8 and 9 were polymeric chain structures with five-coordinate and seven-coordinate tin atoms, compounds 10 and 11 were monomeric structures with six-coordinate and five-coordinate tin atoms.

Novel organotin(IV) compounds derived from bis(organostannyl)methanes: Synthesis and crystal structures of bis[diphenyl(pyridin-2-onato)stannyl]methane and bis[bromophenyl(pyrimidine-2-thionato)stannyl]methane · C 7H 8

Reaction between bis(chlorodiphenylstanyl)methane and the sodium salt of 2-hydroxypyridine (pyONa) in the molar ratio of 1:2 provides the organotin hydroxide derivative [Ph 2(pyO)SnCH 2Sn(OH)Ph 2] 2 ( 1) (where pyO = anion of 2-hydroxypyridine), while reaction of bis(dibromophenylstanyl)methane with the sodium salt of pyrimidine-2-thione (pmtNa) in molar ratio of 1:4 gives the corresponding organotin thiolate derivative, as its toluene solvate [BrPh(pmt)Sn] 2CH 2 · C 7H 8 ( 2) (where pmt = anion of pyrimidine-2-thione). Both compounds were characterized by single crystal X-ray diffraction analysis and contain five-coordinate tin atoms. Compound 1 is a centrosymmetric head-to-tail dimmer with almost symmetrical Sn(1)–O(H)–Sn(2A) bridges.

Condensation Reaction of Dimethyltin(IV) Oxide with 2-(2,3-Dichloroanilino)benzoic Acid Synthesis and Study of a Novel Dimeric Tetraorganodistannoxane

The novel symmetric dimeric tetraorganodistannoxane [(Me2Sn)4(DCPA)2)O2(OH)2] (2) and [(Me2Sn)4(DCPA)2)O2(OC2H5)2] (3) where HDCPA is 2-(2,3-dichloroanilino)benzoic acid (1) have been prepared. The crystal structure of 3 has been determined by X-ray crystallography. Three distannoxane rings are present to the centrosymmetric dimeric tetraorganodistannoxane by virtue of μ3-oxo form the central R4Sn2O2 core with a planar Sn2O2 ring, resulting in a ladder type structural motif. Five-coordinated tin atoms are present in the distannoxane dimer. The ligands act as monodentate agents, thus rendering the tin atom five-coordinated. Significant π → π stacking interactions and intramolecular hydrogen bonds stabilize the structure 3. The polar imino hydrogen atom participates in intramolecular hydrogen bonds. The formation of the dimeric distannoxanes 2 and 3 represent a ladder-type carboxylates in which the insertion of a μ2-OH or a μ2-OC2H5 group occurs. This unusual result can be interpreted in terms of a competition between the strength different donors, in which the –OH or the –OC2H5 groups show higher donor capacity than the carboxylato group of DCPA.

Investigation on the coordination modes: Syntheses, characterization and crystal structures of diorganotin (IV) dichloride with 4(5)-imidazoledithiocarboxylic acid

A series of diorganotin (IV) complexes of the types of R 2SnCl(SSCC 3H 3N 2) (R = CH 3 1, n Bu 2, C 6H 5 3 and C 6H 5CH 2 4), R 2Sn(SSCC 3H 3N 2) 2 (R = CH 3 5, n Bu 6, C 6H 5 7 and C 6H 5CH 2 8) and R 2Sn(SSCC 3H 2N 2) (R = CH 3 9, n Bu 10, C 6H 5 11 and C 6H 5CH 2 12) have been obtained by reactions of 4(5)-imidazoledithiocarboxylic acid with diorganotin (IV) dichlorides in the presence of sodium ethoxide. All complexes are characterized by elemental, IR, 1H, 13C and 119Sn NMR spectra analyses. Also, the complexes 1, 7 and 9 are characterized by X-ray crystallography diffraction analyses, which reveal that the complex 1 is monomeric structure with five-coordinate tin (IV) atom, the complex 7 is monomeric structure with six-coordinate tin (IV) atom and the complex 9 is one-dimensional chain with five-coordinate tin (IV) atom.

An iron–sulfur–tin cluster with amino-ligands and its reactions with thiols

The dinuclear complex Fe 2(μ 2-η 2-S 2)(CO) 6 ( 1) has been reacted with the bis(amino)stannylene Sn(μ-N t-Bu) 2SiMe 2 ( 2) to form the new 1:1 complex Me 2Si(μ-N t-Bu) 2SnFe 2(μ 3-S) 2(CO) 6 ( 4). The ‘double-star’ shape of its Fe 2S 2Sn central core (X-ray structure analysis, multinuclear NMR) contains a tetracoordinated tin atom, which provides a spirocyclic connection between the Fe 2S 2 butterfly and the four-membered SnN 2Si cycle. The reaction can thus be described as an insertion of the divalent tin into the sulphur–sulphur bond of the Fe 2(μ 2-η 2-S 2)(CO) 6 precursor. All distances and angles in 4 are in accordance with tin being in the formal oxidation state +4. The Sn–N bonds in this cluster can serve as excellent targets for the subsequent addition of thiols (sulphanes). Indeed, these bonds are highly reactive and when HS(CH 2) 2SH is allowed to react with 4, the cluster is destroyed and the spiro-cyclic tin sulphide Sn[S 2(CH 2) 2] 2 is the only isolable reaction product. If HS(CH 2) 2SH is replaced by Me 3Si(CH 2) 2SH, the 1:1 adduct Me 2Si(μ-N t-Bu)[μ-N(H) t-Bu]Sn{S(CH 2) 2SiMe 3}(μ 3-S) 2Fe 2(CO) 6 ( 6a) is isolated. This new cluster contains a five-coordinate tin atom (three S and two N donors) and has several functional groups (X-ray structure analysis, NMR). The proton of the thiol reagent Me 3Si(CH 2) 2SH has migrated to one of the nitrogen atoms as a result of selective S–H addition across an Sn–N bond, while the Fe 2S 2Sn core remains intact. To the best of our knowledge, no other tin compound displaying two nitrogen and three sulphur ligands has been structurally described before. To cite this article: M. Veith et al., C. R. Chimie 8 (2005) .

Diorganotin Salicylaldoximate Clusters: Their Fascinating Chemistry and Structures

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and crystal structures of diorganotin dicyanoethylene-1,2-dithiolate compounds and their derivatives with 4,4 ′-Bipy or Phen

Six diorganotin(IV) compounds with dicyanoethylene-1,2-dithiolate (mnt) of the type [R 2Sn(mnt)Cl n L] · Y (when n=0, L=0: R=CH 3, Y=0, 1; R= n-Bu, Y=0, 2; R=C 6H 6, Y=0.5C 6H 6, 3; R=CH 3, Y=1.5(4,4 ′-Bipy), 4; when n=1, L=0, R=CH 3, Y=4,4 ′-Bipy, 5; when n=0, L=Phen, R=CH 3, Y=0, 6; 4,4 ′-Bipy=4,4 ′-bipyridyl; Phen=1,10-phenanthroline) are synthesized by the reaction of diorganotin dichloride and disodium maleonitriledithiolate (Na 2mnt) in the presence of 4,4 ′-Bipy or Phen. All the compounds 1– 6 are characterized by elemental, IR, 1H NMR spectroscopy and X-ray crystallography analyses. The X-ray data showed the geometries of all the tin atoms in compounds 1– 4 are tetrahedral, and those in 5 and 6 are trigonal bipyramidal and distorted octahedral, respectively. Co-crystallization is found in crystals of compounds 3 and 4. The co-crystallized solvents are benzene and 4,4 ′-Bipy, respectively. Compound 5 is a stannate with a five-coordinated tin(IV) atom. Compound 6 is a six-coordinated dimethyltin(IV) derivative from mixed ligands of mnt and Phen.

Synthesis, Characterization and Crystal Structure of Chlorodibenzyltin (IV) Complex with Dithiomorpholinocarbamate Ligand

AbstractChlorodibenzyltin (IV) complex with dithiomorpholinocarbamate ligand was synthesized by the reaction of dibenzyltin dichloride with dithiomorpholinocarbamate in 1:1 stoichiometry. The complex was characterized by elementary analysis, UV, BR and 1H NMR spectra. The crystal structure was determined by X‐ray single crystal diffraction study. The crystallographic data are as follows: triclinic, space group P1, a = 0.8723 (2) ran, b = 1.099 (2) nm, c = 1.1036 (3) nm, α = 86.498 (4)°, β = 89.697 (5)°, γ = 82.807 (5)°, Z = 2, V = 1.0479 (4) nm3, Dc= 1.580 g/cm−3, μ = 1.553 mm−1, F (000) = 500, R1 = 0.0442, wR2 = 0.0974. The crystal consists of discrete molecules containing five‐coordinate tin atoms in a distorted tigonal bipyramidal configuration. The molecules are packed in the unit cell in one‐dimensional chain structure through a weak interaction between the chlorine atom and sulfur atom, the sulfur atom and one of the sulfurs of an adjacent molecule.

Reaction of Butyltin Hydroxide Oxide with p-Toluenesulfonic Acid: Synthesis, X-ray Crystal Analysis, and Multinuclear NMR Characterization of {(BuSn)12O14(OH)6}(4-CH3C6H4SO3)2

The reaction of butyltin hydroxide oxide, BuSnO(OH), with p-toluenesulfonic acid, 4-CH3C6H4SO3H, yields the butyltin oxo cluster {(BuSn)12(μ3-O)14(μ2-OH)6}2+ mixed with a soluble ill-defined butylt...

13C−119Sn Correlation NMR in Solution and Solid-State CP/MAS NMR of Bis(tributylstannyl(IV)) O-5,6-Isopropylidene-l-(+)-ascorbate

Various NMR correlation techniques, 1H−13C HMQC, 1H−13C HMBC, 1H−119Sn HMQC with gradient enhancement, and 13C−119Sn HMQC, enabled a full resonance assignment and the solution structure elucidation of bis(tributylstannyl(IV)) l-(+)-ascorbate (1) and O-5,6-isopropylidene-l-(+)-ascorbate (2) in deuteriochloroform. Double heteronuclear 13C−119Sn HMQC spectroscopy appeared indispensable for discriminating between 2J(13C−O−119Sn) and 3J(13CC−O−119Sn) coupling pathways involving quaternary carbon atoms and provided useful information about the relative magnitudes of 2J(13C−119Sn) and 3J(13C−119Sn) coupling constants, as they turned out to have an uncommon coupling size sequence. While the tin atoms in compounds 1 and 2 are four-coordinate in solution, 117Sn CP/MAS NMR reveals that compound 2 has one four-coordinate and one five-coordinate tin atom in the solid state.

Tin(IV) and organotin(IV) derivatives of novel β-diketones

Abstract 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) A: Sn–O(2)=2.424(5) A). Electronic effects are responsible for the different behavior shown by these trialkyl and triphenyl derivatives.

Spectroscopic studies of triphenyltin azide and of its adducts with O- and N-donor ligands; the crystal and molecular structures of triphenyltin azide and of azido(hexamethylphosphoramide)triphenyltin(IV)

Complete far-IR and Raman data (<400 cm-1) are reported for triphenyltin azide (1) as well as for adducts Ph3SnN3·L (L = hexamethylphosphoramide (HMPA), triphenylphosphine oxide, pyridine-N-oxide, 4-picoline-N-oxide, or pyridine). The small changes in v(Sn-N3) noted on going from (1) to the adducts, as well as solid-state 119Sn nmr data, indicate that (1), like the adducts, has five-coordinate tin atoms. X-ray analysis shows that (1) crystallizes with two different chains of five-coordinate Ph3Sn units joined by 1,3-azide bridges. In one unit, the geometry around tin is similar to that found for the monomeric HMPA adduct (2), which has trans-axial HMPA and azide ligands. The other unit in (1) has nonplanar -SnC3- groups connected by less symmetric 1,3-azide bridges and thus resembles the structure of isoelectronic triphenyltin isocyanate.Key words: triphenyltin azide, O- and N-donor adducts, far-IR/Raman, crystal structures.

Crystal Structures of μ2-Fluoro- and μ2-Salicylaldoximato-Bridged μ3-Oxo-tris(dimethyltin(IV)) Bis(salicylaldoximate)

Crystallographic data for [(Me2Sn)2(Me2SnO)(Nu)(HONZO)(ONZO)] where HONZOH is ortho-HONCH−C6H4−OH, salicylaldoxime, have been obtained for Nu = ONZOH (2) and F (4). Both 2 and 4 display one seven- and two five-coordinate diorganotin moieties as basic features. The key points of interest in 2 are the E-configuration for ONZOH and the observation of an intramolecular O−H···N hydrogen bond which is shown, by comparison with a related structure where such an interaction is precluded, not to impart a special stability in the structure. In 4, a bridging F is present. The F atom forms a stronger interaction with one of the Sn atoms of the cyclic Sn2OF unit, which provides a structural explanation to the observation of regioselective attack of nucleophiles onto one of the five-coordinate tin atoms in these systems.