Hydroxid-halogenid-verbindungen des di-t-butyl-substituierten zinns

Redetermination of the crystal structure of di-μ2-hydroxido-bis-[di-tert-butyl-chlorido-tin(IV)] at 100 K

The structure of the dimeric title compound, [Sn2(C4H9)4Cl2(OH)2], was redetermined at 100 K by use of an area detector to provide new data to improve the structural parameters for detailed analysis. Noteworthy is the folding of the central, non-symmetric, four-membered [SnO]2 ring [dihedral angle about the O⋯O axis = 1.09 (3)°], as well as the elongation of the Sn-Cl bonds [mean value = 2.5096 (4) Å], as a result of inter-molecular O-H⋯Cl hydrogen bonds; the latter lead to a chain-like arrangement of dimeric mol-ecules along [101].

Efficient selective deacetylation of complex oligosaccharides using the neutral organotin catalyst [tBu2SnOH(Cl)]2

Tetra-tert-butyl-3-chloro-1-hydroxydistannoxane has been found to selectively cleave with high efficiency primary acetates on complex oligosaccharides containing esterified l-iduronic acid and bearing an anomeric acetate. This tin based catalyst was found much more effective than magnesium methoxide to carry out selective deacetylation.

Reaction products of diorganotin(IV) oxides, R2SnO, with nitric acid. Part 2 – R = n-butyl and t-butyl

The reaction of diorganotin(IV) oxides, R2SnO with R = n-butyl and t-butyl, with nitric acid in different stoichiometric ratios resulted in the formation of different products depending on the organic groups attached to the tin atom: the diorganotin(IV) dinitrate dihydrates, n-Bu2Sn(NO3)2·2H2O (2d) and t-Bu2Sn(NO3)2·2H2O (2e), the mixed diorganotin(IV) nitrate methoxide oxide n-Bu2Sn(NO3)(n-Bu2SnOMe)O (6), and the diorganotin(IV) nitrate hydroxide hydrate t-Bu2Sn(NO3)(OH)·H2O = [t-Bu2Sn(OH)(H2O)][NO3] (7). On examination of the solubility of the primary reaction products in different solvents, the three additional compounds t-Bu2Sn(NO3)(OH)·DMSO (8), t-Bu2Sn(NO3)(OH)·THF, and 2-t-Bu2Sn(NO3)(OH)·DMF = [t-Bu2Sn(OH)dmf]2[NO3]2·[t-Bu2Sn(NO3)OH]2 (9) could be isolated. All compounds have been structurally characterized by single crystal X-ray diffraction (primary results for 7) with special attention paid to dimensionality (2d and 2c = monomeric, hydrogen bonded molecules; 6 = dimeric molecules of ladder-type structure; 7 = dimeric cation; 8 = dimeric molecule with hydrogen bonded solvent molecules; 9 = both components dimeric), tin coordination (6, 7, 8, and 9 = trigonal bipyramidal; 2d and 2e = eightfold), and nitrate bonding modes (7 and 9 = isolated, hydrogen bonded; 6, 8, and 9 (component 2) = monodentate; 2d and 2e = symmetrical bidentate), the latter one being analyzed using both Sn–O and N–O distances.

On the structural diversity anions coordinate to the butterfly-shaped [(R2Sn)3O(OH)2]2+ cations and vice versa

The syntheses and crystal structures of [(t-Bu2Sn)3O(OH)2]CO3·3MeOH, 1a, [(t-Bu2Sn)3O(OH)2]CO3·3H2O·acetone, 1b, [(t-Bu2Sn)3O(OH)2][I]2·[(t-Bu2Sn(OH)I]2·2DMSO, 1c, and [(Cy2Sn)3O(OH)2][I]2·2DMSO, 2a, all containing the trinuclear [(R2Sn)3O(OH)2]2+ ion have been described. The butterfly shape of this cation is derived from two annulated, four-membered tin–oxygen rings with a central μ3-oxygen atom and trigonal-bipyramidally coordinated tin atom both belonging to both rings and two μ2-hydroxyl groups and two outer, four-fold coordinated tin atoms. In 1a and 1b, the carbonate anions interact with the outer tin atoms of the cations as bidentate chelating ligands in the classical syn–syn coordination mode, and vice versa. In this way, both outer tin atoms expand their coordination sphere from four to five, with the consequence that bond angles and lengths within the cation are determined by the axial and equatorial position of the oxygen atoms within the trigonal-bipyramidal coordination on all three tin atoms. 1c consists of two different building units, an up to now unknown hydroxide iodide of composition [(t-Bu2Sn(OH)I]2 with hydrogen-bonded DMSO molecules and a [(t-Bu2Sn)3O(OH)2]2+ cation with one coordinated and one isolated, via hydrogen bonds connected iodine ion. The hydroxide iodine is built up of two five-fold coordinated tin atoms linked via two hydroxyl groups with exocyclic iodine atoms occupying axial positions at the trigonal-biypramidally coordinated tin atoms. The unprecedented coordination of the iodine ion to the [(t-Bu2Sn)3O(OH)2]2+ cation takes place between both outer tin atoms, resulting in a five-fold, trigonal-bipyramidal coordination at these tin atoms, too. Structural parameters within the so-formed [(t-Bu2Sn)3O(OH)2I]+ complex are very similar to those of 1a and 1b, with the exception of a significant lengthening of the tin–oxygen bonds opposite to the bridging iodine atom. 2a represents the first example of the [(R2Sn)3O(OH)2]2+ cation without R = t-butyl, so far. In the solid, it consists of two crystallographic independent [(Cy2Sn)3O(OH)2][I]2 building units, each connected to two DMSO molecules via hydrogen bonds. Both building units are very similar with respect to their conformation. Each of the iodine anions coordinates with only one of the two outer tin atoms, one in an inwards, one in an outwards to the tin-oxygen framework directed position. These tin atoms are therefore also trigonal-bipyramidally coordinated as in 1a−1c, but because of steric reasons one of the trigonal-bipyramids has changed its orientation within the tin–oxygen framework, accompanied by enormous changes of bond lengths and angles therein.

Reaction products of diorganotin(IV) oxides, R2SnO, with nitric acid. Part 1: R = methyl, ethyl, and isopropyl

The reaction of diorganotin(IV) oxides, R2SnO with R = Me, Et, and i-Pr, with nitric acid in different stoichiometric ratios resulted in the formation of different products depending on the organic groups. The diorganotin(IV) nitrate hydroxides Me2Sn(NO3)(OH) (1a) Et2Sn(NO3)(OH), α-1b, β-1b, i-Pr2Sn(NO3)(OH) (1c), the diisopropyltin(IV) dinitrate dihydrate, i-Pr2Sn(NO3)2·2H2O (2c) and the diisopropyltin(IV) nitrate oxalate dihydrate, [i-Pr2Sn(NO3)]2Ox·2H2O (3) as side-product. On examination of the solubility of the primary reaction products in different solvents, the two additional compounds Me2Sn(NO3)(OH)·DMSO (4) and 2i-Pr2Sn(NO3)2·3DMSO = [i-Pr2Sn(NO3)(dmso)3] [i-Pr2Sn(NO3)3] (5) have been isolated. All compounds have been structurally characterized by single crystal X-ray diffraction with special respect to dimensionality (1a, α-1b, 1c = dimeric molecules hydrogen bonded to one-dimensional chains; β-1b = two-dimensional coordination polymer; 2c = monomeric; 3 = monomeric, tin atoms linked via a double side-on chelating oxalate ion; 4 = dimeric, 5 = monomeric anion/cation), tin coordination (trigonal-bipyramidal = 1a, α-1b, 1c; six-fold = β-1b; seven-fold = 3, 4, 5-cation; eight-fold = 2c, 5-anion) and nitrate bonding modes (monodentate = 1a, α-1b, 1c; unsymmetrical bidentate = 3, symmetrical bidentate = 3, 4, 5-cation, 5-anion; syn-anti bridging = β-1b), the latter one being analysed using both, Sn–O and N–O distances.

Di-μ-hydroxido-bis-[bromidodi-p-tolyl-tin(IV)]

The Sn atoms in the dinuclear title compound, [Sn₂Br₂(C₇H₇)₄(OH)₂], exist in distorted trigonal-bipyramidal BrSnC₂O₂ coordination geometries. Each of the two independent dinuclear mol­ecules comprising the asymmetric unit is disposed about a center of inversion. In the crystal, molecules are linked by an O—H⋯ hydrogen bond.

Bismethylene triphosphate nucleotides of uridine 4-phosphate analogues: a new class of anionic pyrimidine nucleotide analogues

Cytidine-5'-triphosphate synthase (CTPS) catalyzes the formation of cytidine triphosphate (CTP) from glutamine, uridine 5'-triphosphate (UTP), and adenosine 5'-triphosphate (ATP). This reaction proceeds via formation of the high-energy intermediate UTP-4-phosphate (UTP-4-P). Stable analogues of UTP-4-P may be potent inhibitors of CTPS and useful as lead structures for the development of anticancer and antiviral agents. Several bismethylene triphosphate (BMT) nucleotides of uridine 4-phosphate (U-4-P) analogues have been prepared. A key step was the selective methanolysis, with the aid of a tin catalyst, of the 5' ester moiety of 2',3',5'-tri-O-acetyl or tri-O-benzoyl U-4-P analogues. We believe this represents the first general approach to the selective cleavage of 5' benzoyl esters in benzoylated nucleosides. Mitsunobu coupling of these 5'-deprotected U-4-P analogues to an unsymmetrical, protected BMT bearing a free phosphonic acid moiety at one of the terminal positions gave fully protected BMT-U-4-P analogues. Global deprotection of these species was achieved using TMSBr followed by treatment with NH4OH-MeOH or NH4OH-pyridine. The resulting BMT nucleotides represent a new class of anionic pyrimidine nucleotide analogues.

Inorganic-Cored Photoactive Assemblies: Synthesis, Structure, and Photochemical Investigations on Stannoxane-Supported Multifluorene Compounds

Organostannoxanes were used as inert supports for the preparation of multichromophore assemblies. The synthesis involves a single-step procedure and allows the preparation of compounds in which the number of chromophore units can be varied from one to six. Thus, the reactions of LCOOH (1-fluorenecarboxylic acid) or L'COOH (9-fluorenecarboxylic acid) with various organostannoxane precursors afforded the fluorenyl derivatives [Ph(3)SnO(2)CL] (1), [Ph(3)SnO(2)CL'] (2), [{nBu(3)SnO(2)CL''}(n)] (3), [{nBu(3)SnO(2)CL'}(n)] (4), [{tBu(2)Sn(OH)O(2)CL}(2)] (5), [{tBu(2)Sn(OH)O(2)CL'}(2)] (6), [{[nBu(2)SnO(2)CL](2)O}(2)] (7) [{[nBu(2)SnO(2)CL'](2)O}(2)] (8), [{nBuSn(O)O(2)CL}(6)] (9), and [{nBuSn(O)O(2)CL'}(6)] (10). Interestingly, the formation of 3 is accompanied by an unusual oxo-transfer reaction. The ligand L is oxidized at the 9-position. Compounds 1, 3, 5, 7, and 8 were characterized by X-ray crystallography. The solid-state structures of these compounds reveal rich supramolecular structures owing to multiple intermolecular interactions between the various supramolecular synthons present in these molecules. The optical behavior of 1-10 is primarily dictated by the fluorenyl periphery. These compounds display strong blue fluorescent emission in solution and blue-green fluorescent emission in the solid state. Fluorescence lifetimes of all of these compounds are on the nanosecond timescale, and this suggests that the emission originates from the singlet excited state to the ground state. Intermolecular interactions in the solid state lead to considerable broadening of the emission bands.

Organostannoxane-Supported Multiferrocenyl Assemblies: Synthesis, Novel Supramolecular Structures, and Electrochemistry

Organostannoxane-based multiredox assemblies containing ferrocenyl peripheries have been readily synthesized by a simple one-pot synthesis, either by a solution method or by room-temperature solid-state synthesis, in nearly quantitative yields. The number of ferrocenyl units in the multiredox assembly is readily varied by stoichiometric control as well as by the choice of the organotin precursors. Thus, the reaction of the diorganotin oxides, R2SnO (R = Ph, nBu and tBu) with ferrocene carboxylic acid affords tetra-, di-, and mononuclear derivatives [{Ph2Sn[OC(O)Fc]2}2] (1), [{[nBu2SnOC(O)Fc]2O}2] (2), [nBu2Sn{OC(O)Fc}2] (3), [{tBu2Sn(OH)OC(O)Fc}2] (4), and [tBu2Sn{OC(O)Fc}2] (5) (Fc = eta(5)C5H4-Fe-eta(5)C5H5). The reaction of triorganotin oxides, R3SnOSnR3 (R = nBu and Ph) with ferrocene carboxylic acid leads to the formation of the mono-nuclear derivatives [Ph3SnOC(O)Fc] (6) and [{nBu3SnOC(O)Fc}(n)] (7). Molecular structures of the compounds 1-4 and 6 have been determined by single-crystal X-ray analysis. The molecular structure of compound 1 is new among organotin carboxylates. In this compound, ferrocenyl carboxylates are involved in both chelating and bridging coordination modes to the tin atoms to form an eight-membered cyclic structure. In all of these compounds, the acidic protons of the cyclopentadienyl groups are hydrogen bonded to the carboxylate oxygens (C-HO) to form rich supramolecular assemblies. In addition to this, pi-pi, T-shaped, L-shaped, and side-to-face stacking interactions involving ferrocenyl groups also occur. Compound 6 shows an interesting and novel intermolecular CO2-pi stacking interaction. Electrochemical analysis of the compounds 1-4, 6, and 7 shows a single, quasi-reversible oxidation peak corresponding to the simultaneous oxidation of four, two, and one ferrocenyl substituents, respectively. Compound 5 shows two quasi-reversible oxidation peaks. This is attributed to the positional difference among the ferrocenyl substituents on the tin atom. Additionally, while compounds 2 and 4 are electrochemically quite robust and do not decompose even after ten continuous CV cycles, compounds 1, and 3, 5-7 start to show decomposition after five cycles.

Highly efficient deacetylation by use of the neutral organotin catalyst [tBu2SnOH(Cl)]2

Deprotection of acetyl esters is effected cleanly by the neutral organotin catalyst, [tBu2SnOH(Cl)]2. The mildness of the reaction gives rise to great synthetic versatility and in the process a variety of functional groups are tolerated. Differentiations between primary, secondary, and tertiary alcohols and between acetyl ester and other esters are feasible. No racemization occurs with chiral acetyl esters. Exclusive deprotection of primary acetyl esters in carbohydrates and nucleosides is observed. The crude product thus obtained can be used for further reactions without purification.

Reactions of Dimethyl Sulfite with Diorganotin Oxides. One-Pot Synthesis of Methoxydiorganotin Methanesulfonates through the Arbuzov Rearrangement, Spectroscopic Characterization of These Compounds and Their Derivatives, and X-ray Crystal Structures of n-Bu(2)Sn(X)OS(O)(2)Me (X = acac, bzbz, OH)

One-pot reactions of diorganotin oxides, R(2)SnO, with dimethyl sulfite under reflux conditions (125-127 degrees C) proceed via the Arbuzov rearrangement at the sulfur center, yielding the corresponding methoxydiorganotin methanesulfonates, R(2)Sn(OMe)OS(O)(2)Me [R = n-Pr (1), n-Bu (2), i-Bu (3), c-Hx (4)], as white, hygroscopic solids. These compounds react with beta-diketones [acetylacetone (Hacac), benzoylacetone (Hbzac), and dibenzoylmethane (Hbzbz)] to afford mixed-ligand organotin derivatives, R(2)Sn(X)OS(O)(2)Me [X = acac, R = n-Pr (5), n-Bu (6); X = bzac, R = n-Pr (7), n-Bu (8); X = bzbz, R = n-Pr (9), n-Bu (10), i-Bu (11)]. Selective hydrolysis of the Sn-OMe bond in 1-3 occurs, resulting in the isolation of (&mgr;-hydroxo)diorganotin methanesulfonates, R(2)Sn(OH)OS(O)(2)Me [R = n-Pr (12), n-Bu (13), i-Bu (14)]. All the compounds are characterized by elemental analyses and IR, multinuclear ((1)H, (13)C, and (119)Sn) NMR, and mass spectra. Unequivocal evidence of the presence of the methanesulfonate group is provided by the X-ray crystal structures of 6, 10, and 13. [For 6: trigonal space group R&thremacr; (No. 148), a = 28.664(1) Å, c = 13.056(1)Å, Z = 18. For 10: triclinic space group P&onemacr; (No. 2), a = 13.056(3) Å, b = 14.062(3) Å, c = 16.282(3) Å, Z = 4. For 13: triclinic space group P&onemacr; (No. 2), a = 9.089(2) Å, b = 12.040(2) Å, c =13.894(2) Å, Z = 2]. For 6 and 10, the solid-state structural analyses reveal dimeric structures with a bridging bidentate methanesulfonate group forming a centrosymmetric eight-membered ring. Compound 13 possesses a polymeric sheet structure with repeating 20-membered macrocycles (including two four-membered [Sn(OH)](2) rings) by virtue of the bridging bidentate methanesulfonate groups. A search for a possible pathway to give Arbuzov-rearranged products 1-4 leads us to speculate that there is an initial catalytic transformation of dimethyl sulfite to methyl methanesulfonate via intermediate compounds, Bu(2)Sn(OMe)(2) (A) and [Bu(2)SnOMe](2)O (B). A and B subsequently react with methyl methanesulfonate to give 1-4.

Reactions of [t-Bu(2)SnO](3) with [t-BuX(2)Si](2) (X = F, Cl). Syntheses and Structures of Novel Stannasiloxanes and of [(t-Bu(2)FSn)(2)O](2), the First Fluorine-Containing Tetraorganodistannoxane(,)

Di-tert-butyltin oxide, (t-Bu(2)SnO)(3) (1), reacts with 1,2-di-tert-butyltetrachlorodisilane, (t-BuCl(2)Si)(2) (2), to provide the stannasiloxane t-Bu(2)Sn[OSi(OSnCl-t-Bu(2))-t-Bu](2) (4, racemate). The reaction of 1 with 1,2-di-tert-butyltetrafluorodisilane, (t-BuF(2)Si)(2) (3), provides the stannasiloxane [t-Bu(F)SiOSn-t-Bu(2)](2)O (5, meso/racemate mixture) and the tetraorganodistannoxane [t-Bu(2)(F)SnOSn(F)-t-Bu(2)](2) (6). Under loss of (1)/(3) mole equiv of 1, the stannasiloxane 5 is transformed into t-Bu(2)Sn[OSi(F)-t-BuSi(F)-t-BuO](2)Sn-t-Bu(2) (7). Its ten-membered ring structure was elucidated by X-ray analysis. In solution, 7 forms the five-membered ring t-Bu(2)Sn[OSi(F)-t-Bu](2) (7a). The dimeric nature of 6 was confirmed by its crystal structure determination. In solution, 6 exhibits a unique valence tautomerism as evidenced by (19)F and (119)Sn NMR spectroscopy.

Molecular Dynamics within Diorganotin Systems: Solution and Solid State Studies of New Mixed Distannoxane Dimers [(t)Bu(2)(Cl)SnOSn(Cl)R(2)](2)

Di-tert-butyltin oxide, ((t)Bu(2)SnO)(3), reacts with R(2)SnCl(2) to give mixed distannoxanes [(t)Bu(2)(Cl)SnOSn(Cl)R(2)](2) (1, R = Me; 2, R = Et; 3, R = (i)Pr; 4, (n)Bu) whereas di-tert-butyltin hydroxide chloride, [(t)Bu(2)Sn(OH)Cl](2), reacts with [(n)Bu(2)SnO](n) to give the chlorohydroxydistannoxane [(t)Bu(2)(OH)SnOSn(Cl)(n)Bu(2)](2), 5; the dimeric nature of these tetraorganodistannoxanes was confirmed by crystal structure determinations of 1 and 4. Although stable in the solid state, compounds 1-4 rearrange to give a number of distannoxanes in solution. Addition of R(2)SnCl(2) (R = Me, (i)Pr, (n)Bu) to solutions of 1, 3, and 4, respectively, causes displacement of (t)Bu(2)SnCl(2) with concomitant formation of [((t)Bu(2)SnCl(2))(R(2)SnO)(2)(R(2)SnCl(2))] and [(R(2)SnCl(2))(R(2)SnO)(2)(R(2)SnCl(2))]. Thus 1-4 can be regarded as (R(2)SnO)(2) units which are stabilized by two (t)Bu(2)SnCl(2) molecules. NMR data indicate that reaction between ((t)Bu(2)SnO)(3) and (t)Bu(2)SnCl(2) gives rise to an equilibrium involving linear [(t)Bu(2)Sn(Cl)OSn(Cl)(t)Bu(2)] and the novel three-quarter ladder compound [(t)Bu(2)SnCl(2)][(t)Bu(2)SnO](2). Formation of trinuclear tin species is also evident from electrospray mass spectrometric studies.