Exocyclic Tin Atom Research Articles

Coordination geometry of monomeric, dimeric and polymeric organotin(IV) compounds constructed from 5-bromopyridine-2-carboxylic acid and mono-, di- or tri-organotin precursors

Reactions of mono-, di-, tri-alkyltin chlorides or oxide with 5-bromopyridine-2-carboxylic acid result in five new organotin(IV) compounds, [MeSn(O2CC5NH3Br)Cl2(H2O)]·(C2H5)2O (1), [(n-Bu)Sn(O2CC5NH3Br)Cl2(H2O)]·(C2H5)2O (2), {[(n-Bu)2Sn(O2CC5NH3Br)]2O}2 (3) [(n-Bu)3Sn(O2CC5NH3Br)]n (4) and [Ph3Sn(O2CC5NH3Br)]n (5), which have been characterized by single crystal X-ray diffraction, element analysis, IR, 1H, 13C and 119Sn NMR. Three different coordination modes for the ligand are demonstrated in this group of compounds: (1) bidentate mode with the pyridyl nitrogen atom and carboxyl oxygen atom for mono-alkyltin compounds 1 and 2, in which six-coordinated tin center is also bound with two chlorine ions and one water molecule; (2) compound 3 is a tetranuclear centrosymmetric dimer with a central Sn2O2 four-membered ring. The four tin atoms are linked by two bridging carboxyl groups while the remaining two act as monodentate ligands to the endo- and exo-cyclic tin atoms; (3) for tri-alkyltin compounds 4 and 5, the bidentate bridging carboxylic group coordinates with two different tin atoms through the SnOCO→Sn bond, and the carboxylate bridge propagates 1D polymeric chains, typical for five coordinate tin. However, in compounds 3–5, the pyridyl nitrogen atoms do not participate in the coordination. For triorganotin(IV) polymers 4 and 5, the solution studies show the collapse of the intermolecular interactions observed in the solid state to yield monomeric species.

Synthesis, characterization and cytotoxic assay on human liver carcinoma cells (HepG2) of organodistannoxane dimer complexes derived from alkylaminobenzoic acids

A total number of five organodistannoxane dimer complexes derivative of alkylaminobenzoic acids have been successfully synthesized and characterized quantitatively and qualitatively. Results of the infrared spectroscopy of the acids and complexes showed that the coordination took place via oxygen atoms from the carboxylate group. This indicated that the carboxylate anions acted as mono- and bidentate ligand. From the 119Sn NMR solution study, complexes 1 and 5 exhibited two well resolved signals, one lying in the range of five-coordinated geometry and the other in the range of six-coordinated geometry. Moreover, all the exo- and endo-cyclic tin atoms in complexes 2-4 were five-coordinated indicated that a pair of carboxylate anions was bonded to the tin atoms in a monodentate manner while the other two carboxylate anions were bonded to the tin atoms (endo and exo-cyclic tin atom) in a bridging bidentate manner. From the cytotoxic assay study, complex 1 revealed a significant result compared to complexes 2-5. Key words: Organodistannoxane dimer, synthesis, characterization, cytotoxic assay.

Synthesis and Structural Studies on Tetranuclear Tin Compositions Containing Tin {[R2Sn(LH)]2O}2 Moieties (R = Bu or Oct and LH = 4‐[((E)‐1‐{2‐Hydroxy‐5‐[(E)‐2‐(aryl)‐1‐diazenyl]phenyl}methylidene)‐ amino]benzoate)

AbstractDiorganotin compounds containing tetranuclear tin compositions of the type {[R2Sn(LH)]2O}2 in which LH is deprotonated carboxylic acid LHH′ (H′ are the carboxylic and H the phenolic protons of the benzoic acid) HO2C–C6H4‐4‐{N=C(H)C6H3‐2‐OH‐5‐(N=N–C6H4X)} (X = H for L1H, X = 2‐CH3 for L2H, X = 3‐CH3 for L3H, and X = 4‐CH3 for L4H; R = Bu or Oct), were synthesized and characterized by FT‐IR, NMR, and 119Sn Mössbauer spectroscopy. One of the complexes, {[Oct2Sn(O2CC6H4{N=C(H)C6H3‐2‐OH‐5‐(N=NC6H4CH3‐2)})]2O}2 was characterized by single‐crystal X‐ray diffaraction, which revealed that the compound is a centrosymmetric tetranuclear bis(dicarboxylatotetrabutyldistannoxane) complex with a planar Sn4O2 core. The two μ3‐oxo oyxgen atoms are connected to a Sn2O2 ring and to two exocyclic tin atoms. The four carboxylate ligands display two different modes of coordination. Both modes of coordination involve bridging two structurally distinct tin atoms. The solution structures of the complexes were unravelled by 119Sn NMR spectroscopy, and found to be identical to those of the crystalline state.

A novel self-assembling of mixed tri- and dibutyltin macrocyclic complex with solvothermal synthesis method

The self-assembled reaction of 2-hydroxynicotinic acid, KOH and tri- n-butyltin chloride in CH 3OH and H 2O (V/V = 5:1) under solvothermal condition (150 °C) affords a novel mixed tri- and dibutyltin macrocyclic complex 1. Characterization of the complex 1 was achieved using elemental analysis, IR, NMR ( 1H, 13C and 119Sn) spectroscopy, TGA and X-ray crystallography diffraction analysis. X-ray data revealed that it is an unusual 16-membered macrocycle containing eight tin atoms, and they can be divided into four sorts by the distinct environments, the endocyclic tin atoms are best described as five- and six-coordinate and the exocyclic tin atoms as five-coordinate. Furthermore, a 2D corrugated sheet is formed by intermolecular C–H⋯Cl, O–H⋯N and O–H⋯O weak interactions.

Synthesis, Characterization, and Structural Studies of Mixed-Ligand Diorganotin Esters, [R2Sn(OP(O)(OH)Ph)(OS(O)2R1)]n [R = n-Bu, R1 = Me (1), n-Pr (2); R = Et, R1 = Me (3)] with 1D and 3D Coordination Polymeric Motifs

Mixed-ligand diorganotin esters, [R 2Sn(OP(O)(OH)Ph)(OS(O) 2R (1))] n [R = n-Bu, R (1) = Me ( 1), n-Pr ( 2); R = Et, R (1) = Me ( 3)], have been synthesized by reacting the tin precursors, R 2Sn(OR (1))OS(O) 2R with an equimolar amount of phenylphosphonic acid under mild conditions (room temperature, 6-8 h, CH 2Cl 2). These have been characterized by IR, multinuclear ( (1)H, (13)C{ (1)H}, (31)P, and (119)Sn) NMR, and single crystal X-ray diffraction studies. The asymmetric unit of 1 is comprised of a tetramer with four crystallographically unique tin atoms. The structure reveals a central eight-membered (Sn-O-S-O) 2 cyclic ring with two exocyclic tin atoms, which results from micro 3-binding of the two methanesulfonate groups. The remaining two sulfonates are monodentate and contribute in O...HO(P) hydrogen bonding. The molecular structure is extended into a 3D coordination polymer with the aid of hydrogenphenylphosphonate group on each tin atom, acting in a micro 2-O 2P mode and forms a series of eight-membered (Sn-O-P-O) 2 rings in the structural framework. 2 and 3 are isostructural and represent linear 1D coordination polymers via micro 2-binding mode of both alkanesulfonate and hydrogenphenylphosphonate groups.

Synthesis, Characterization and Crystal Structure of the Bis(2,4-dinitrobenzoato)tetrabutyldistannoxane(IV) Dimer

The title compound, bis(2,4-dinitrobenzoato)tetrabutyldistannoxane(IV), was obtained from the reaction of di-n-butyltin(IV) oxide with 2,4-dinitrobenzoic acid. It crystallizes out as the usual dicarboxylatotetrabutyldistannoxane(IV) dimer. In the monoclinic system P21/c, a = 12.391(3) A, b = 19.937(5) A, c = 15.026(4) A, α = γ = 90°, β = 102.857(2)°, V = 3618.95(16) A3 and Z = 2. A crystal structure determination of the title compound reveals the presence of a centrosymmetric planar Sn2O2, with two different environments for tin atoms and two distinct carboxylate groups. Two of the carboxylate groups are bonded to the exocyclic tin atom in a bidentate bridging manner and the remaining two carboxylate groups are bonded to the tin atom in a monodentate manner. As a result, both the tin atoms moieties in the complex are five coordinate and exhibit trigonal bipyramid geometry. Synthesis, Characterization and Crystal Structure of the Bis(2,4-dinitrobenzoato)tetrabutyldistannoxane(IV) Dimer Yip Foo Win, Teoh Siang Guan, Lim Eng Khoon, Shea Lin Ng, Hoong Kun Fun A crystal structure determination of the title compound reveals the presence of a centrosymmetric planar Sn2O2, with two different environments for tin atoms and two distinct carboxylate groups.

A Novel Macrocyclic Dimeric Dicarboxylato Distannoxane Assembled from a Flexible Dicarboxylic Acid

The novel macrocyclic complex [(Bu2Sn)2OL]2•CH3CN (2) has been prepared from the flexible dicarboxylic acid, LH2, (1). Single crystal X-ray diffraction shows that complex 2 has a centrosymmetric structure, with a central rhomboid cyclic Bu4Sn2O2 unit, linked at the oxygen atoms to two exocyclic tin atoms. The dicarboxylate ligands bridge exocylic and endocyclic tin atoms, completing two rings each of 22 atoms, and two of the four carbonyl oxygen atoms coordinate to the exocyclic tin atoms, to raise their coordination state to five and complete two more six-membered, rings.

Synthesis and structural characterizations of diorganotin(IV) complexes with 2-pyrazinecarboxylic acid

Two types of diorganotin(IV) complexes {[R 2Sn(O 2CC 4H 3N 2)] 2O} 2 (R = n-octyl 1, 2- ClC 6H 4CH 2 3, 2- FC 6H 4CH 2 5, 4- FC 6H 4CH 2 7) and R 2Sn(O 2CC 4H 3N 2) 2 (R = n-octyl 2, 2- ClC 6H 4CH 2 4, 2- FC 6H 4CH 2 6, 4- FC 6H 4CH 2 8) were prepared by reactions of diorganotin oxide with 2-pyrazinecarboxylic acid. The complexes 1– 8 are characterized by elemental analysis, IR and NMR ( 1H, 13C, 119Sn) spectroscopies. The complexes {[( n-C 8H 17) 2Sn(O 2CC 4H 3N 2)] 2O} 2 ( 1) and ( n-C 8H 17) 2Sn(O 2CC 4H 3N 2) 2 ( 2) are also determined by X-ray single crystal diffraction, which reveal that the endo-cyclic tin atom of complex 1, is seven-coordinate, and the exo-cyclic tin atom is hexa-coordinated geometry, while the complex 2 is seven-coordinated geometry. The nitrogen atom of the aromatic ring participates in the interactions with the Sn atom.

Synthesis and characterization of dimeric organotin compounds {[(ArCH2)2 Sn(2-quin)]2O}2 and crystal structure of {[(2-ClC6 H4CH2)2Sn(2-quin)]2O}2

Ten new dimeric organotin compounds {[(ArCH2)2 Sn(2-quin)]2O}2 (Ar = Ph 1, 2-ClC6H42, 3-ClC6H43, 4-ClC6H44, 2-FC6H45, 3-FC6H46, 4-FC6H47, 4-BrC6H48, 4-CNC6H49, 2,4-Cl2C6H310) have been synthesized by dealkylation reactions of 2-quinH with [(ArCH2)3Sn]2O, and their structures have been characterized by elemental analysis, IR and NMR (1}H, 13C, 119Sn) spectroscopies. The structures of {[(2-ClC6H4CH2)2Sn(2-quin)]2O}22 have been determined by X-ray diffraction. Studies show that compound 2 has a tetranuclear, centrosymmetric dimeric structure, with the endo-cyclic tin atom five-coordinated and the exo-cyclic tin atom six coordinated. Studies also show that the nitrogen atoms of the 2-quin ligand are coordinating to the tin atom for all the ten compounds. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:152–159, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20194

Synthesis and spectroscopic properties of [ N-(4-carboxyphenyl) salicylideneiminato] di- and tri-organotin (IV) complexes and crystal structures of {[ nBu 2Sn(2-OHC 6H 4CH [dbnd]NC 6H 4COO)] 2O} 2 and Ph 3Sn(2-OHC 6H 4CH [dbnd]NC 6H 4COO)

Reactions of R 2SnO (R: n Bu, Cy, Ph, PhCH 2) and R 3SnCl (R: Ph, Cy, PhCH 2, 2- Cl-PhCH 2, 4- F-PhCH 2, 4- Cl-PhCH 2) with N-(4-carboxyphenyl)-salicylideneimine (LH 2) in 1:1 stoichiometry afford complexes {[R 2Sn(LH)] 2O} 2 and R 3Sn(LH). These complexes have been characterized by elemental analyses, IR, 1H and 119Sn NMR spectroscopy. The crystal structures of {[ n Bu 2Sn(LH)] 2O} 2, 1 and Ph 3Sn(L), 5 are determined by single crystal X-ray diffraction. Results showed that in the solid state the complex 1 is a tetranuclear centrosymmetric dimer with six-coordination being assigned to both the endo-cyclic and exo-cyclic tin atoms after consideration of close intermolecular tin oxygen contacts, and study show that the imino nitrogen atom do not participate in coordination to the tin atom. The complex 5 is a monomer, and in the molecule the tin atoms are five-coordinated in trigonal bipyramidal geometries with the two oxygen atom of the carboxylate both coordinating to the tin atoms.

Synthesis and crystal structure of macrocyclic di- n-butyltin(IV) complex with 2-mercapto-4-methyl-5-thiazoleacetic acid, {[ n-Bu 2Sn(O 2CCH 2C 4H 3NS)SS(C 4H 3NSCH 2CO 2)Sn n-Bu 2]O} 2

A novel macrocyclic di- n-butyltin(IV) complex 1 was synthesized by the reaction of di- n-butyltin(IV) oxide and 2-mercapto-4-methyl-5-thiazoleacetic acid. Characterization of the complex 1 was achieved using elemental analysis, IR, 1H, 13C and 119Sn NMR spectra and X-ray diffraction. X-ray data of the complex 1 revealed that it is an unusual macrocycle containing the bridging-S–S-linkages and tetranuclear ladder based on a planar four-membered Sn 2O 2 ring. In the so-called ladder structure, there are two distinct tin environments, the endocyclic tin atom is best described as five-coordinate and the exocyclic tin atom as six-coordinate.

1,3 Dichloro- and 1,3 dibromotetra- n-butyldistannoxane mixtures: ligand redistribution and fluxional dynamics in distannoxanes

The halogen redistribution reaction in the binary [ n Bu 2SnCl] 2O/[ n Bu 2SnBr] 2O system is examined by 119Sn- and 13C-NMR spectroscopy. Binary mixtures of [ n Bu 2SnCl] 2O and [ n Bu 2SnBr] 2O reach equilibrium rapidly at room temperature. The reactant dimers are found to be in equilibrium with all five possible mixed distannoxane dimers in the equimolar mixture. These mixed distannoxane dimers differ in the ratio of Cl and Br as well as the relative positioning of the halogens. The mechanism responsible for the rapid formation of the mixed Cl:Br distannoxane dimers is found to proceed via bimolecular collisions producing a four-centered transition state, which in turn undergoes a concerted exchange of the halogens. The equilibrium concentrations of the reactant and product dimers are well represented by a statistical distribution, indicating that Cl and Br exhibit equivalent donor abilities. At 298 K, the NMR spectral data are consistent with time-averaged structures arising from rapidly interconverting rigid ladder pairs. Lowering the temperature to 173 K failed to freeze out this fluxional process. A reversible configurational rearrangement is also observed in which rotation about the oxygenexocyclic tin bond results in the mutual exchange of halogens associated with the same exocyclic tin atom.

119Sn-NMR spectroscopic study of the 1,3-dichloro- and 1,3-diacetoxytetra- n-butyldistannoxane binary system

The binary [ n Bu 2SnCl] 2O/[ n Bu 2SnOAc] 2O (OAc=O 2CCH 3) system is re-examined using 119Sn-NMR spectroscopy. Binary mixtures of [ n Bu 2SnCl] 2O and [ n Bu 2SnOAc] 2O reach equilibrium rapidly, producing all five possible mixed distannoxane dimers, differing in the ratio and relative positions of Cl and acetoxy ligands. The rapid formation of the product dimers results from the intermolecular exchange of the ligands one at a time. The 119Sn-NMR spectral data are consistent with time-averaged ladder structures arising from rapidly interconverting ladder pairs. The equilibrium concentrations of the binary mixtures indicate that positional ordering of the ligands exists in the mixed dimers. A reversible configurational rearrangement is also observed in which the ligands associated with the same exocyclic tin atom undergo mutual exchange via rotation about the oxygen–exocyclic tin bond. The 119Sn spectral data of the binary system leads to the unambiguous assignment of the tin resonances of {[ n Bu 2SnOAc] 2O} 2: δ exo=−216.1 ppm, δ endo=−227.9 ppm.

Octabutyl-1κ2C,2κ2C,3κ2C,4κ2C-bis-μ3-oxo-1:2:3κ3O;1:3:4κ3O-tetrakis[μ-(2-pyridinecarboxylatoN-oxide)]-1κ2O,O':2κO;2κO:3κ2O,O';3κ2O,O':4κO;1κ2O,O':4κO-tetratin Hydrate

The unit cell of the title compound, bis[1,1,3,3-tetrabutyl-1,3-bis(picolinato N-oxide)distannoxane] hydrate, [Sn4(O)2(C4H9)8(C6H4NO3)4].H2O, contains two independent centrosymmetric dicarboxylatotetraorganodistannoxane dimers, one of which is hydrogen bonded to two water molecules. Both dimers possess a planar Sn2O2 core unit, the O atoms of which are covalently bonded to two [dibutyl(picolinato N-oxide)tin] units. The endocyclic Sn atoms (of the Sn2O2 core units) are six-coordinate in C2SnO4 skew-trapezoidal bipyramidal environments, whereas the exocyclic tin atoms {of the [dibutyl(picolinato-N-oxide)tin] units} are seven-coordinate in trans-C2SnO5 pentagonal bipyramidal environments.

On the assignment of 119Sn resonances of bis[dicarboxylatotetraorganodistannoxanes] in solution and solid state 119Sn NMR spectra

The scope and limitations of 119Sn resonance assignment strategies for structural characterizations of bis[dicarboxylatotetraorganodistannoxanes] by 2D gradient assisted 1H– 119Sn HMQC NMR in solution and MAS 119Sn NMR in the solid state are discussed for three compounds, the structure of which was already known by X-ray diffraction, bis[diacetatotetramethyldistannoxane] ( 1), bis[bis(2,2-dimethylpropanoato)tetramethyldistannoxane] ( 3), bis[bis(pentafluorobenzoato)tetra- n-butyldistannoxane] ( 4) and for the novel compound bis[bis(4-methylbenzoato)tetramethyldistannoxane] ( 2), for which an X-ray crystal structure is also reported. The structures of {R′COO(R 2Sn)–O–(SnR 2)OOCR′} 2 each feature a central R 8Sn 4O 2 core, and in addition to the μ 3-oxo links between the endo- and exo-cyclic tin atoms, the carboxylate ligands associating in a variety of structural motifs. Their relationship to 119Sn MAS NMR patterns, in particular, the principal components of the 119Sn shielding tensors, is discussed.

X‐Ray Structure and In Vitro Anti‐Tumoural Activity of the Dimeric Bis[(2‐Phenyl‐1,2‐Dicarba‐Closo‐Dodecaborane‐1‐Carboxylato)‐Di‐n‐Butyltin] Oxide

X-ray diffraction studies reveal the structure of {[(2-C6H5-1,2-C2B10H10-1-COO)Bu2Sn]2O}2, 1, to conform to the common motif found for {[(R′COO)R2Sn]2O}2 compounds. The dimer features a central Bu2Sn2O2 unit (two-fold symmetry) with the two Bu2Sn groups being linked via bridging oxygen atoms, each of which also carries an exocyclic Bu2Sn moiety. The two pairs of exo- and endo-cyclic tin atoms are each linked via an almost symmetrically bridging carboxylate ligand and the two remaining ligands coordinate an exocyclic tin atom only, in the monodentate mode. The in vitro anti-tumour activity of 1, determined against a variety of cell lines, is compared with those of the corresponding 2-methylcarboranylacetate, derivative 2, and with clinically used compounds.

Synthesis, characterization andin-vitro antitumour activity of dibutyltin carboxylates involving the perfluorophenyl moiety: Crystal structure of the dimeric bis[(4-fluoro- and pentafluoro-benzoato)di-n-butyltin] oxides

Crystal structure determinations of {[(F 5 C 6 COO)Bu 2 Sn] 2 O} 2 and {[(4F-C 6 H 4 COO)-Bu 2 Sn] 2 O} 2 show that the structures are similar and feature central Bu 4 Sn 2 O 2 units with two Bu 2 Sn groups connected by bridging oxygen atoms. Each pair of exo- and endo-cyclic tin atoms is linked by an almost symmetrically bridging carboxylate group, with the two remaining groups attached to the exocyclic tin atom only. Crystals of {[(F 5 C 6 COO)Bu 2 Sn] 2 O) 2 are triclinic, space group P1, with unit cell dimensions a=12.425(3) A, b= 13.090(5) A, c=11.697(3) A, α=95.31(3)°, β= 93.28(2)°, γ=113.01(2)°, V=1734(1) A 3 , Z=1. Crystals of {[(4-F-C 6 H 4 COO)Bu 2 Sn] 2 O} 2 are also triclinic, space group P1, a=12.599(6) A, b= 25.359(4) A, c=11.480(4) A, α=91.44(3)°, β= 114.77(3)°, γ=97.43(3)°, V=3289(2) A 3 , Z=2. The structures were refined to final R=0.046, R w =0.046 for 4312 reflections with l≥3.0 σ(l) for {[(F 5 C 6 COO)Bu 2 Sn] 2 O} 2 and R = 0.061, R w = 0.068 for 4112 reflections with l≥3.0 σ(l) for {[(4-F-C 6 H 4 COO)Bu 2 Sn] 2 O} 2

X-ray structure of the dimeric bis[(1,7-dicarba- closo-dodecaborane-l-carboxylato)-di-n-butyltin] oxide

X-ray diffraction studies reveal the structure of {[(1,7-C 2B 10H 11-1-COO)Bu 2Sn] 2O} 12 to be analogous to most other {[RCOO)Bu 2Sn] 2)O} 2 compounds. The dimer features a central Bu 4Sn 2O 2 unit with the two Bu 2Sn groups being linked via bridging oxygen atoms, each of which also carries an exocyclic Bu2Sn moiety. The two pairs of exo- and endo-cyclic tin atoms are each linked via a symmetrically bridging carboxylate ligand and the two remaining ligands coordinate the exocyclic tin atom only, in the monodentate mode. The in vitro anti-tumour activity of this compound, against a variety of cell lines, is compared with those of clinically used compounds.

Molecular structure of 1,2;3,4,di-μ,-nitrobenzoato-OO'-1,3-bis( o, m-, or p-nitrobenzoato)-l,2,4;2,3,4-di-μ 3-oxotetrakis [di-n-butyltin(IV)] compounds

Infrared, Mössbauer and multinuclei ( 1H, 13C, 119Sn) NMR spectral data for the title compounds and single crystal X-ray data for the ortho isomer only reveal that these compounds contain two bridging and two non-bridging (monodentate) nitro-benzoato groups. These data further confirm the existence of two six-coordinate endocyclic and two five-coordinate exocyclic tin atoms in these dimers.

Structural chemistry of organotin carboxylates IV. Synthesis and spectroscopic properties of diorganotin(IV) complexes with o-anisic acid. The crystal and molecular structure of [ nBu 2Sn(2-MeOC 6H 4COO)] 2O 2

Reactions of diorganotin(IV) oxides with o-anisic acid in 1 1 and 1 2 stoichiometry afford complexes of the type [R 2Sn(2-MeOC 6H 4COO)] 2O 2 (I) and [R 2Sn(2-MeOC 6H 4COO) 2] (II) (R = Me, Et, nPr, nBu), respectively. These complexes have been characterized by elemental analyses, IR and NMR ( 1H, 13C and 119Sn) spectroscopy, and I shown to adopt a dimeric ladder structure whereas II has the usual monomeric diorganotin dicarboxylate structure. The oxygen atom of the methoxy group of the ligand does not participate in bonding to the tin atom. This conclusion is supported by an X-ray diffraction study. The compound [ nBu 2Sn(2-MeOC 6H 4COO)] 2O 2, (Id), showed that in solid Id there are two unique, centrosymmetric dimers in the asymmetric unit. The individual molecules conform to the tetraorganostannoxane structure, with six-coordination being assigned to both the endocyclic and exocyclic tin atoms after consideration of close intermolecular tin to oxygen contacts. Crystals are triclinic with space group P 1 and unit cell dimensions a 13.503(3), b 24.226(4), c 11.917(1) Å, α 102.21(1), β 108.54(2), and γ 89.92(1)°. The structure was refined by a blocked-matrix least-squares procedure to final R = 0.052 for 5505 reflections with I ⩾ 2.5σ( I).