Tin-carbon Bond Research Articles

Reaktivität metallorganischer Komplexe mit Zinn-Metall-Bindung, IV [1]. SO2 -Insertion an phosphinsubstituierten und anionischen Triorganozinn-Komplexen des Chroms, Molybdäns und Wolframs / Reactivity of Organometallic Complexes Containing Tin-Metal Bonds, IV [1]. SO2 Insertion into Phosphine Substituted and Anionic Triorganotin Complexes of Chromium, Molybdenum and Tungsten

Abstract The trans phosphane and phosphite substituted organotin complexes of molybdenum 1-4 are prepared by thermolysis or photolysis of the tricarbonyl parent compounds. The phosphane complexes 1 and 2 react readily with liquid sulfur dioxide by absorption of 1-3 moles of SO2 depending on temperature. IR and NMR spectra indicate cleavage of tin-carbon bonds only yielding insertion products of the sulfinato-O type 1a-c and 2a-c. The phosphite complexes 3, 4 are less reactive and yield a di-insertion 3a and a mono-insertion compound 4a. The anionic triphenyltin derivatives of chromium, molybdenum and tungsten 5-7 undergo facile cleavage of 1 (Cr) or 3 (Mo, W) tin-phenyl bonds. The course of SO2 insertion into 1-7 reveals a distinct activation of the Sn-C bond in organotin transition metal complexes by substitution with stronger donor molecules or reduction to anionic species.

The reactivity of small-ring monostannacycloalkanes : III. Ring-expansion reactions of 1,1-dimethyl-1-stannacyclopentane

As a result of the enhanced reactivity of the endo-cyclic tincarbon bond 1,1-dimethyl-1-stannacyclopentane readily undergoes ring-expansion reactions with a variety of substrates to produce new organotin heterocycles. Illustrative examples include ring-expansion reactions with oxygen, sulphur, sulphur dioxide, diiron noncarbonyl, dichlorocarbene and diethyl azodicarboxylate.

C-Stannane derivatives of carbohydrates

Triphenyltin lithium (1) was reacted separately with 1,2:3,5-di-O-methylene-6-O-tosyl-α-D-glucofuranose (2), with methyl 2,3-anhydro-4,6-O-benzylidene-α-D-allopyranoside (4), and with methyl 2,3-anhydro-4,6-O-benzylidene-α-D-mannopyranoside (6), to form in each case a sugar-stannane derivative having a stable carbon-tin bond. These products have been studied by 1H and 13C nmr spectroscopy.

Cleavage of α-(phenylthio)alkylboranes with N-chlorosuccinimide. A convenient route to monothioacetals and acetals

α-(Phenylthio)alkylboranes, which are easily prepared by two different homologation processes, are deboronated by N-chlorosuccinimide in mildly basic methanol to form monothioacetals or, with excess reagent, dimethyl acetals. Both boronic esters and trialkylboranes react, the latter considerably faster. The reaction is specific for the sulfur-substituted alkylborane group, suggesting that initial chlorination occurs at sulfur. Under free radical conditions, α-(phenylthio)alkaneboronic esters are cleaved to α-(phenylthio)alkyl chlorides by either N-chlorosuccinimide or sulfuryl chloride. Pinacol phenylthio(triphenylstannyl)methaneboronate with sulfuryl chloride yielded (phenylthio)dichloromethane, without any evidence of selectivity between carbontin and carbonboron bond cleavage.

The reactivity of small-ring monostannacycloalkanes : II. Transalkylation reactions of 1,1-dialkyl-1-stannacycloalkanes. Synthesis of new metal-functionally substituted stannacycloalkanes

Comparative studies of halodemetallation (Cl 2, Br 2, I 2) and trans-alkylation (Me 4- n SnCl n , GeCl 4, HgCl 2) reactions of 1,1-dimethyl-l-stannacyclo-pentane, -hexane and -heptane are described. In the case of the five-memberedring compounds, both halodemetallation and transalkylation reactions proceed exclusively by ring cleavage, rather than by demethylation, which points to substantial strain. These transalkylation reactions proved to be most valuable for the synthesis of new types of unsymmetric organotin compounds, such asMe 2ClSn(CH 2) 4SnCl n Me 3- n ( n = 1—3), Me 2ClSn(CH 2) 4GeC1 3, Me 2C1Sn(CH 2) 4HgC1. Reactions of the six- and seven-membered ring systems with iodine likewise proceed by preferential cleavage of the endo-cyclic tin—carbon bond; the order of cleavage being: (CH 2) 4Sn > (CH 2) 5Sn > (CH 2) 6Sn > MeSn. However, possibly as a result of steric effects, a rather different reactivity order is observed in transalkylation reactions with tin and mercury halides: (CH 2) 4Sn > MeSn > (CH 2) 5Sn > (CH 2) 6Sn. On the basis of the latter observations a new synthesis for1-chloro-1-methyl-1-stannacyclo-hexane and -heptane was developed. These compounds are shown to be useful starting materials for the synthesis of a variety of new metal-functionally substituted stannacycloalkanes.

Reaktivität metallorganischer komplexe mit zinn-metall-bindung : II. Umsetzungen von (organostannyl)pentacarbonylmangan- und -rhenium-derivaten mit flüssigem schwefeldioxid

The reactions of Ph 3SnMn(CO) 5 (Ia) und Ph 3SnRe(CO) 5 (Ib) in liquid sulfur dioxide lead to cleavage of Sn-C bonds only and insertion of 2 or 3 mol SO 2. The primary bis(sulfinato-O) complexes, III(a,b) are easily rearranged to the more stable O,O′-sulfinates IV(a,b) (polymeric) and Va (monomeric). In the range of 20 – 60°C, the monomeric tris(sulfinato-O,O′) complexes VI(a,b) are formed. In Me 3SnMn(CO) 5 (IIa),only the Sn-Mn bond is attacked yielding adducts of changing composition, e.g. Me 3SnMn(CO) 5·1.5 SO 2 (VIIa). In contrast, Me 3SnRe(CO) 5 (IIb) undergoes insertion into one Sn-C bond (sulfinato-O,O′ complex, VIIIb). Ph 2Sn[Mn(CO) 5] 2 (IX) absorbs 3 mol SO 2 under cleavage of 1 Sn-Mn and 2 Sn-C bonds (→ X) at 60°C. As a whole, the insertion of the weak Lewis acid sulfur dioxide into the tin-carbon bond is preferred. Structure and properties of the resulting products are discussed on the basis of their IR, NMR and mass spectra.

Reactivity of organometallic complexes containing tin-metal bonds. Activation or deactivation of tin-carbon bond towards electrophilic substitution?

As numerous experiments with electrophilic reagents have shown, organotin-transition metal complexes may be formally considered as pseudohalides. Hence there is an activation of aromatic and a deactivation of aliphatic tin-carbon bonds.

The reactivity of small-ring monostannacycloalkanes I. The catalytic polymerization of 1,1-dimethyl-1-stannacyclopentane

A comparative study has been made of the reactivity of small-ring 1,1-dialkyl-1-stannacyclo-pentanes, -hexanes and -heptanes towards a variety of electrophilic and nucleophilic reagents. In the case of the five-membered heterocycles the reactivity of the tincarbon bonds of the ring is considerably higher than that of the alkyltin bonds, indicating substantial ring strain. 1,1-Dimethyl-1-stannacyclopentane was unexpectedly found to be extremely susceptible to polymerization under polar conditions; the half-life at 60°C in methanol is only about 3 h. The resulting [Me 2Sn(CH 2) 4] n oligomer has an average chain length of n ≈ 7. Polymerization does not occur under free radical conditions.

Preparation and infrared characterisation of some new organotin carboxylate polymers

There has been considerable interest in recent years in the synthesis and structure of monoorganotin polymers [l-3] containing carboxylate groups. Cleavage of the tin-carbon bond by carboxylic acids under rigorous conditions has so far been applied for the synthesis of these polymers. In this paper we wish to report the preparation of a few new polymers using a relatively convenient route involving cleavage reactions of tin-carbon bonds in triorganotin carboxylates (R$nOCOR where R = phenyl, Ph; Propyl, Pr; Butyl, Bu; Cyclohexyl and R’ = H, CH2, CH,CH,) with mercury(I1) salts such as mercuric halides and acetate. In a typical reaction run, to a solution of triorganotin carboxylate in ether or benzene, a solution of mercuric salt (1: 1) in ether was added dropwise with stirring. Although a white precipitate was formed immediately, the mixture was stirred for a further 4 hours at room temperature to ensure complete reaction. The volatiles were removed and the residual solid was extracted with hot benzene which left a white insoluble polymeric material (infusible up to 360 ‘C, except for the formate; -0COH group containing polymers which decomposed at about 270 “C). The benzene extract on fractional crystallisation afforded triorganotin halide and organomercuric halide. By contrast, reaction of mercuric acetate with triphenyltin acetate afforded diphenyl mercury and a tin polymer. The products obtained from these reactions were characterised by analytical and spectral data. Considering the stoichiometry, the following equations may be proposed to account for the reaction products:

Bioorganotin chemistry: Reactions of tributyltin derivatives with a cytochrome P-450 dependent monooxygenase enzyme system

The biological oxidation of several tributyltin derivatives, by a cytochrome P-450 dependent monooxygenase enzyme system with reduced nicotinamideadeninedinucleotidephosphate as the essential cofactor, produced carbon-hydroxylated compounds identified as α-, β-, γ- and δ-hydroxybutyldibutyltin derivatives. The hydroxylation pattern and the lack of oxidative cleavage of tin-carbon bonds strongly suggest a free radical rather than an oxenoid mechanism, while the predominance of β-carbon-hydroxylation further implies some role of the tin-carbon σ electrons in directing the site of hydroxylation.

On the structure-activity relationships and mechanism of organotin induced, nonenergy dependent swelling of liver mitochondria

Organotin-induced, nonenergy dependent swelling of isolated rat liver mitochondria has been investigated. The organotins which were most active as swelling agents had three carbon-tin bonds, n-octanol: water partition coefficients greater than one, extracted chloride ions from water into benzene, and facilitated the diffusion of chloride ions through a benzene phase. Compounds having one, two, or four carbon-tin bonds exhibited low activity as swelling agents. Mitochondria were most sensitive to organotin-induced swelling when the major cation in the medium was the ammonium or triethylammonium ion; however, high concentrations of active organotins caused swelling which was independent of the nature of the medium. Bis-(triphenyltin)-sulfide exhibited low activity and sodium sulfide, BAL, or dithiothreitol protected mitochondria from organotin-induced swelling. The results suggest that low levels of active organotins may induce swelling by acting as foreign, anion specific ionophores in the inner mitochondrial membrane and that saturation of high capacity-low affinity mitochondrial binding sites by these compounds results in extensive and nonspecific alterations of the permeability of the mitochondrial membranes.

Bestimmung des nucleophilen Charakters der Zinn-Kohlenstoff-Bindung, II / Determination of the Nucleophilicity of Tin-Carbon Bond, II

The SO2-insertion into tin-carbon bonds of mixed tetraorganostannanes, R3SnR′ (R=C6H5, CH3; R'=CH3, C6H5, CH2=CH), is determined by the nucleophilicity of the organic residue attached to metal and shows a decreasing rate in the order aryl > alkenyl > alkyl. A correlation to Taft’s constant is given. The behaviour of triphenylvinyltin toward sulfur dioxide is in good agreement with this rule, as the insertion of one or two moles of SO2 takes place only into Sn—C6H5 bond.

Systematische untersuchungen über das verhalten von organozinn-verbindungen gegenüber flüssigem schwefel-dioxid : V. Reaktionen von perfluorierten organozinn-derivaten Mit SO 2

To get a clear conception of the mechanism of SO 2 insertion into tin-carbon bonds, reactions of perfluorinated organotin compounds with liquid SO 2 were studied in detail. Of the pure perfluoroorgano derivativs (C 6F 5) 4Sn is completely inert, while (CF 2CF) 4Sn shows a slight reactivity. In mixed tetraorganotin compounds like (C 6H 5) 3SnC 6F 5 and (C 6H 5) 3SnCFCF 2 insertion takes place only into the tinphenyl bond. The case of (CH 3) 3SnC 6F 5 is interesting in so far that the presence of the C 6F 5 group deactivates the whole molecule towards attack by SO 2. Possible reasons for this effect are discussed. We also report on the synthesis of triphenyltin perfluoromethanesulfinate, (C 6H 5) 3SnO 2-SCF 3.

The reaction of iodine monochloride and monobromide with tetraorganotins

The reactions of iodine monochloride and iodine monobromide with a tetraalkyltin (butyl) and a tetraaryltin (phenyl) have been studied with a view to establishing their utility as routes to organotin chlorides and bromides respectively. Rapid high yield syntheses of the triorganotin bromides, diorganotin dichlorides and trialkyltin chloride were achieved. Some further suggestions are made on the mechanism of interhalogen fission of tincarbon bonds.

Bestimmung des nucleophilen Charakters der Zinn-Kohlenstoff-Bindung, I / Determination of the Nucleophilicity of Tin-Carbon Bond, I

The SO2-insertion into the tin-carbon bond of mixed tetraorganostannanes, R3SnR’ (R = alkyl, R’ = aryl, and vice versa), is determined by the nucleophilicity of the organic residue attached to metal, the ease of cleavage decreasing in the order aryl > alkenyl ⪢ alkyl. As has been proved by chemical and spectroscopic methods the reaction of triphenylmethyltin with liquid sulfur dioxide follows the above rule: Sn—CH3 bond remains unattacked, but one or two moles of SO2 can be inserted into Sn—C6H5 bonds depending on experimental conditions.

The mechanism of stabilization of poly(vinyl chloride). II. Cleavage of organotin sulfur compounds by anhydrous hydrogen chloride

A number of organotin compounds of the type RnSn Y4–n, where R = alkyl or aryl; Y = alkylthio, arylthio or carbothiolate; and n = 1, 2, 3 have been prepared and treated with hydrogen chloride at 180°C in o-dichlorobenzene solution. The organotin compounds were also tested at 190°C as thermal stabilizers for PVC. Cleavage of tin–carbon bonds by hydrogen chloride was demonstrated in some cases by analysis of the organotin–hydrogen chloride reaction products. The formation of monoalkyl(aryl)tin chlorides or stannic chloride, or both, in the model system was shown to correspond to a catastrophic mode of degradation in the polymer. The use of stabilizers with fewer than two alkyl or aryl groups on tin also gave this mode of degradation.

The hemolytic activity of some trialkyltin and triphenyltin compounds

Triphenyltin chloride caused the rapid hemolysis of dog, hog, rabbit, or rat blood; however, human blood was resistant to hemolysis by triphenyltin chloride. Trialkytin compounds with alkyl groups having 3–6 carbon atoms were hemolytic to both human and rat blood. Tri- n-butyltin derivatives in which the fourth group or atom bonded to tin was acetate, methoxide, hydroxide, oxygen, bromide or chloride were all hemolytic; however, bis(triphenyltin) sulfide was not hemolytic. Butyltins having 1, 2 or 4 carbon-tin bonds, trimethyltin chloride and triethyltin bromide all exhibited low hemolytic activity. It was demonstrated that the rate of hemolysis of human blood by tri- n-butyltin chloride was reduced when the solutes of the medium were predominantly nonelectrolytes and that potassium leaked from the cells faster than hemoglobin during tri- n-butyltin induced hemolysis. A nitrogen atmosphere or the addition of low concentrations of dl-α-tocopherol also reduced the rate of hemolysis of human blood in the presence of tri- n-butyltin chloride. Human plasma, but not human serum albumin, was partially effective in protecting washed, human red cells from tri- n-butyltin induced hemolysis. Sodium sulfide and several sulfhydryl compounds, in concentrations about equal to that of the organotin, protected human and rat blood from the hemolytic activity of tri- n-butyltin chloride, tricyclohexyltin hydroxide, or triphenyltin chloride. It was concluded that the most hemolytic organotins were the trialkyltins with alkyl groups having 3–6 carbon atoms and that some sulfhydryl compounds can react chemically with the organotins to reduce hemolytic activity.

Reactions of alkali metal derivatives of metal carbonyls : XIV. TinCarbon bond cleavage in reactions of iodomethyl-trimethyltin with metal carbonyl anions

Reactions of (CH 3) 3SnCH 2I with the sodium salts NaMo(CO) 3C 5H 5, NaFe(CO) 2C 5H 5, NaMn(CO) 5, and NaCo(CO) 4 in tetrahydrofuran did not give the corresponding (CH 3) 3SnCH 2M(CO) x (C 5H 5) y derivatives but instead rfesulted in cleavage of a carbontin bond to give the corresponding trimethyltin derivatives (CH 3) 3SnM(CO) x (C 5H 5) y (M = Mo, x = 3, y = 1; M = Fe, x = 2, y = 1; M = Mn, x = 5, y = 0; M = Co, x = 4, y = 0) and methyl derivatives CH 3M(CO) x (C 5H 5) y (M = Mo, x = 3, y = 1; M = Fe, x = 2, y = 1; M = Mn, x = 5, y = 0).

Structural studies in main-group chemistry. Part VI. Crystal and molecular structure of 2,2′-bipyridyldichlorodiphenyltin

The crystal structure of the title compound has been determined by single-crystal X-ray diffraction. Crystals are monoclinic, space group P21/n, with Z= 4 in each unit cell of dimensions a= 9·5208(24), b= 13·1583(36), c= 16·5437(40)A, β= 93·600(17)°. The structure was solved by the heavy-atom method and refined by full-matrix least-squares methods to R 0·049 for 1896 independent reflections. The tin atoms are octahedrally co-ordinated by a bidentate 2,2′-bipyridyl residue, two cis-chlorine atoms, and two phenyl groups which are mutually trans. The two tin–carbon bond distances are identical [mean r(Sn–C) 2·152 A], as are the two tin–chlorine bond distances [mean r(Sn–Cl) 2·509 A]. The bipyridyl group is not planar, one C5H4N ring being twisted 4·2° with respect to the other, with the two Sn–N distances unequal (2·344 and 2·375 A). The bond angles subtended at tin by adjacent ligands all fall in the range 85·5–95·6°. The two phenyl groups are not exactly trans(C–Sn–C 173·5°), and are not equivalent. The plane of one phenyl group almost exactly bisects the Cl–Sn–Cl and N–Sn–N bond angles, whilst the other is rotated 79·5° with respect to the first.

Reduction of aryltrimethylsilanes as a synthetic method. Part I. Electrochemical reduction

Electrochemical reduction of aryltrimethyl-silanes and -germanes affords a convenient preparative route to silyl- and germyl-substituted cyclohexa-1,4-dienes, since in most cases the products resist further reduction. The nature of the products is in accord with a Birch-type reduction mechanism. Trimethyl(phenyl)silane gives cyclohexa-2,5-dienyltrimethylsilane in 79% yield. The three bis(trimethylsilyl)benzene isomers and trimethyl-m-tolylsilane give the isomers predicted on the basis of the electronic effects of the substituent groups, but trimethyl-p-tolylsilane, in which the directing effects conflict, gives a mixture of products. Steric as well as electronic influences are probably important. Trialkyl(phenyl)germanes behave analogously to trimethyl(phenyl)silane, but trimethyl(phenyl)tin undergoes cleavage of the tin–carbon bond. The two stereoisomers of 3,6-bis(trimethylsilyl)cyclohexa-1,4-diene were isolated and tentatively assigned configurations.