Gualtiero Plazzogna

Allylbutyltin halides (CH2CHCH2)SnBu3−nCln (n = 0, 1, 2, 3). Preparation, carbon-13 NMR characterization and allylstannylation ability towards ketones and aldehydes

Abstract Mixed allylbutyltin halides (CH 2 CHCH 2 )SnBu 3-n Cl n ( n = 0–3) have been prepared, and characterized by carbon-13 NMR spectroscopy. Their ability to bring about allylstannylation of ketones and aldehydes, to form organostannoxy compounds, Bu 3-n SnCl n OC(R′)(R″)CH 2 CHCH 2 , has been shown to increase on increasing the value of n , that is on increasing the acceptor ability of the tin centre.

The structure of dichlorodimethylbis(pyrazole-N2)tin(IV)

Abstract The structure of the complex Sn(CH3)2Cl2·2C3H4N2 has been determined by single crystal X-ray diffraction methods. The compound crystallizes in the monoclinic system, space Group C2/c (no. 15), with unit cell dimensions a 14.010(4), b 7.906(3), c 13.617(4) A, β 114.7(3)°, and Z = 4. The configuration about the tin atom is all-trans-octahedral. The pyrazole ligands, coordinated through the imino nitrogen atom, are intramolecularly and intermolecularly hydrogen bonded to the chloride ligands, the N(1)H … Cl distances being 3.480 and 3.297 A, respectively. Structural features of the complex are compared with those of other complexes of N-bonded heterocyclic ligands of the type Sn(CH3)2Cl2·2L.

The crystal structure of dichlorobis(N-methylimidazole)dimethyltin(IV)

Abstract The structure of the complex dichlorobis( N -methylimidazole)dimethyltin(IV), Me 2 SnCl 2 ( N Miz) 2 , has been determined from three-dimensional X-ray diffraction data. The compound crystallizes in the triclinic space group P 1 , and the cell parameters are: a 7.218(2), b 7.441(3), c 7.972(3) A, α 114.1(1), β 104.05(10), γ 97.8(1)°, Z = 1. The coordination geometry about the tin atom is all- trans octahedral; the N Miz. ligands are bonded to the metal through their pyridine-like nitrogen atom. The SnC, SnCl and SnN bond distances are 2.118(5), 2.571(3) and 2.329(5) A, respectively. The 1 H NMR spectra are consistent with the presence of a trans -octahedral structure for Me 2 SnCl 2 ( N Miz) 2 in solution, also.

The cleavage by iodine of the tin-tin bond in R6Sn2 compounds. Kinetics and mechanism

Abstract The rates of cleavage of selected ditin compounds by iodine have been measured in alcoholic solvents. Possible mechanisms for the cleavage are discussed. It is concluded that an acyclic four-center intermediate, formed after attachment of solvent in a fast preliminary step, provides the best explanation of the experimental results.

The preparation and properties of some trivinyltin carboxylates

Abstract Trivinyltin carboxylates (CH 2 CH) 3 SnOOCR′ (R′= CH 3 , C 2 H 5 , CH 2 Cl, CF 3 ) have been prepared by an electrochemical procedure, in which tetravinyltin reacts with mercury(I) ions generated electrolytically in methanol containing the appropriate sodium carboxylate as supporting electrolyte. The new compounds obtained are appreciably soluble in THF, less soluble in chloroform, and much less soluble in carbon tetrachloride. Their IR spectra in solid, Nujol mulls and in solution reveal that the compounds are polymers, containing five-coordinated tin atoms in a trigonal bipyramidal structure with bridging carboxylate groups. The SnC region bands, either in solid or in solution, show that the three vinyl groups do not lie in the equatorial plane. Molecular weight determinations show that depolymerization occurs in chloroform, in which the compounds are unassociated except for the acetate, which is trimeric.

Hydrogen bonding in the coordination of N- and S-donor heterocycles to dialkyltin dihalides. Synthesis and structure of trans-dibromodicyclohexylbis(pyrazole-N2)tin(IV), trans-dibromodicyclohexylbis(imidazole-N3)tin(IV), and dibutyldichloro[1-methyl-2(3H)-imidazolinethione-S]tin(IV)

Abstract Hexacoordinate octahedral crystalline complexes of dicyclohexyltin dibromide with pyrazole ( 1 ) and imidazole ( 2 ) have been prepared. The X-ray structures have been determined and the effect of the bulkiness of the alkyl groups bonded to the tin on aspects of the structures (such as intra-and inter-molecular hydrogen bonding, orientation of the ligand plane, and SnN bond length) is discussed. As an example of a pentacoordinate trigonal bipyramidal complex, the 1:1 adduct of dibutyltin dichloride with 1-methyl-imidazoline-2-thione ( 3 ) has been synthesized and its structure studied.

Synthesis and crystal structure of poly-trivinyltinferrocenoate

Abstract Binuclear complexes of formula C 5 H 15 FeC 5 H 4 COOSn(CHCH 2 ) 3 (I), C 5 H 5 FeC 5 H 4 COOSnPh 3 (II) and Ph 3 GeCOOSnPh 3 (III) have been prepared and characterized by IR spectra. The polymeric structure of solid C 5 H 5 FeC 5 H 4 COOSn(CHCH 2 ) 3 has been established by X-ray crystallography. The crystals are monoclinic, space group P 2 1 / a , with a 15.105(5), b 10.030(4), c 11.402(4) A, and β 104.06(4)°. In this compound the tin atoms are five-coordinate trigonal bipiramidal, with the vinyl groups equatorial and two apical oxygen atoms from bridging carboxylato groups. The resulting structure is a linear polymer with SnO bond lengths of 2.12 and 2.42 A. The spectra indicate that similar polymeric structure exist also for compounds II and III in the solid state, whereas an equilibrium monomer ⇄ dimer seems to be present in CHCl 3 solution for the compound III.

Electrochemical preparation of trimethyltin carboxylates

Abstract Trimethyltin carboxylates have been prepared electrochemically. Trimethyltin ions are produced by reaction of tetramethyltin with mercury(I) ions electrolytically generated in methanol containing sodium carboxylate as supporting electrolyte. Trimethyltin formate, acetate, propionate and chloroacetate have been prepared: these compounds are appreciably soluble in solvents such as chloroform and carbon tetrachloride. Molecular weight determinations and IR spectra in solution show a low degree of association in the concentration range 3–30 mg/ml.

The crystal structure of dichlorodivinylbis(pyrazole-N2)tin(IV)

Abstract The crystal structure of the complex Sn(CHCH 2 ) 2 Cl 2 · 2C 3 H 4 N 2 has been determined. The compound crystallyzes in the monoclinic space group C 2/ c , with four molecules in a unit cell of dimensions a 13.634(2), b 8.960(2), c 13.482(2) A, and β 115.0(1)°. The structure is centrosymmetric at the tin atom, with all trans -octahedral coordination geometry. The pyrazole ligands, bonded to the metal through their pyridine-like nitrogen atom, are intermolecularly hydrogen bonded to the chloride ligands. Relevant features of the structure of the title compound are compared with those of the corresponding complexes of dimethyltin dichloride with pyrazoles.

The preparation and properties of some allyltin carboxylates:R3SnOOCR′ (R′ = CH3, CH2Cl), R2Sn(OOCR′)2 (R′ = CH2Cl, CHCl2) and [R2Sn(OOCR′)]2O (R′ = CH2Cl, CHCl2, CCl3)

Abstract Triallyl- and diallyltin carboxylates [(CH 2 CHCH 2 ) 3 SnOOCR′ with R′ = CH 3 and CH 2 Cl, (CH 2 CHCH 2 ) 2 Sn(OOCR′) 2 with R′ = CH 2 Cl and CHCl 2 )] and tetraallyl-1,3-diacyloxydistannoxanes {[(CH 2 CHCH 2 ) 2 SnOOCR′] 2 with R′ = CH 2 Cl,CHCl 2 and CCl 3 }, have been prepared from the reaction of tetraallytin with carboxylic acids in methanol. These compounds have been characterized, and some of their properties have been established by IR spectra and molecular weight determinations.