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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.

In the metallacycle 1-chloro-2,5-dithiastibolane, [Sb(SCH 2 ) 2 Cl], antimony(III) conserves a residual coordination ability. Adducts with monodentate (dimethyl sulfoxide) and chelating (2,2′-bipyridine and 1,10-phenanthroline) ligands were obtained and characterized by IR spectra. The X-ray crystal structure of chloro(1,10-phenanthroline)(ethane-l,2-dithiolato[2−]− S , S ′)antimony(III) has shown that two independent molecules are contained in asymmetric units. The coordination geometry about the antimony is distorted rectangular pyramidal without any intermolecular association.

The reaction of sodium 1,2-benzenedithiolate with methyltin trichloride in water gives the benzenedithiolate of methyltin(IV) as a yellow precipitate. The structure of this compound has been determined by single-crystal X-ray diffractometry. The molecule consists of two benzol[ c ]1,2,3-dithia-stannolanyl moieties held together by a bridging benzene-1,2-dithiolate ligand. The geometry about the tin could be described as distorted tetrahedral, even if in view of the short intramolecular Sn⋯S contacts the structure is better regarded as involving pentacoordinate tin in a distorted trigonal bypyramid.

2-Chloro-2-n-butyl-1,3-dithia-2-stannacyclopentane has been prepared and the structure of its, 1,10-phenanthroline complex, C 18 H 21 ClN 2 S 2 Sn, has been determined by an X-ray diffraction study. The geometrical parameters indicate a distorted octahedral structure about the tin atom. The chlorine atom is trans to one nitrogen of the ligand in axial position, and the sulphur atoms, the carbon bonded to the tin and the other nitrogen form the equatorial plane. The SnS 2 C 2 ring adopts an envelope form. No intermolecular contacts are observed.

The new complex Sn(CHCH 2 ) 2 Cl 2 · 2C 3 H 4 N 2 S has been obtained as a crystalline solid. The crystal structure has been determined by an X-ray diffraction study, which reveals that the tin atom is hexa-coordinate trans -octahedral and the molecule is centrosymmetric. The imidazole ligands are bonded to the metal through the S atom. Each Cl atom is involved in intra- and inter-molecular hydrogen bonding with the NH groups of heterocyclic rings. Relevant structural details are consistent with values for related compounds.

The structure of the title compound, bis(4-amino-2-oxo-1,2-dihydropyrimidinium) tetrachlorodimethylstannate(IV), (C 4 H 6 N 3 O) 2 [SnCl 4 (CH 3 ) 2 ], consists of discrete C 4 H 6 N 3 O + (cytosinium) cations and [SnCl 4 -(CH 3 ) 2 ] 2- anions in which the Sn atom is six-coordinate trans-octahedral. The crystal packing of the ionic complex is stabilized by intermolecular N-H...Cl bonds between the anions and neighbouring cytosinium cations.

4-Bromopyrazole, which is much less basic than the corresponding pyrazole but with similar hydrogen-bonding acidity, gives stable solid hexacoordinate complexes with dimethyl- and divinyl-tindichloride. The crystal structure of the trans-octahedral compound Sn(CH3)2Cl2 · 2C3H3BrN2 was determined by X-ray crystallography and refined to R = 0.030. Intra-molecular hydrogen bonds are probably responsible for the essentially coplanar orientation of the pyrazolic ring plane with the SnCl2N2 plane. The packing is stabilized by inter-molecular hydrogen bonding.

Spirocyclic bis(ethane-1,2-dithiolato[2−]-S,S′)tin(IV) forms hexacoordinate crystalline complexes with pyridine and 2-(2-pyridyl)ethylamine. The compounds have been prepared by conventional methods and the crystal structures have been determined by an X-ray diffraction study. In the parent compound the tin is tetracoordinate in a highly distorted tetrahedral structure, with a weak intermolecular Sn···S interaction. On the contrary, the adducts are essentially octahedral about the tin, with longer SnS bonds in the five-membered rings SnS 2 C 2 . The 2-(2- pyridyl)ethylamine ligand is bonded to the metal through the aminic nitrogen.

The new complex Sn(CHCH 2 ) 2 Cl 2 · 2C 3 H 4 N 2 S has been obtained as a crystalline solid. The crystal structure has been determined by an X-ray diffraction study, which reveals that the tin atom is hexa-coordinate trans -octahedral and the molecule is centrosymmetric. The imidazole ligands are bonded to the metal through the S atom. Each Cl atom is involved in intra- and inter-molecular hydrogen bonding with the NH groups of heterocyclic rings. Relevant structural details are consistent with values for related compounds.

The structure of (C 5 H 7 N 2 ) 2 [Sn(CH 3 ) 2 Cl 4 ] has been determined by X-ray diffraction. The compound crystallizes in the orthorhombic system, space group Pbca (No. 61), with unit cell dimensions a 15.585(2), b 17.561(2), c 7.088(1) A, and Z = 4. The structure consists of hydrogen-bonded chains of alternating [Sn(CH 3 ) 2 Cl 4 ] 2− anions and pairs of C 5 H 7 N 2 + cations. Each trans -dimethyltetrachlorostannate(IV) octahedral unit is surrounded by four 2-aminopyridinium ions and is involved in ten hydrogen-bonding interactions with d (NH⋯ Cl) ranging from 3.242(12) to 3.463(12) A. 1 H NMR data show that (C 5 H 7 N 2 ) 2 [Sn(CH 3 ) 2 Cl 4 ] is formed along with 1,3-dichloro-1,1,3,3-tetramethyldistannoxane in the reaction of Sn(CH 3 ) 2 Cl 2 and C 5 H 6 N 2 in moist CDCl 3 ; the fact that hydrolysis of the dimethyltin dichloride takes place is related to the relatively high basicity and low coordinating tendency of 2-aminopyridine.

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 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 reactions of divinyldiallyltin and carboxylic acids R′COOH [R′, = H, CH 3 , CH 2 Cl, CHCl 2 , CCl 3 , CF 3 ) in water-acetone at room temperature afford the following products: trivinyltin carboxylate for R′ = H, CH 3 ; trivinyltin monochloroacetate together with tetravinyl-1-monochloroacetoxy-3-hydroxy-distannoxane (type B) and tetravinyl-1,3-bis(monochloroacetoxy)-distannoxane (type A) for R′ = CH 2 Cl; both distannoxanes of type A and B for R′ = CHCl 2 and CCl 3 ; only that of type A for R′ = CF 3 . The trivinyltin derivatives having R′ = H, CH 3 , CH 2 Cl seem to be produced by a disproportionation reaction of the appropriate distannoxanes. This process has been experimentally established for R′ = CH 2 Cl and is favoured by protic media (H 2 O(CH 3 ) 2 CO, CH 3 OH) in comparison with aprotic so1vents (CH 3 CN, CHCl 3 ).

Complexes of 3,5-dimethylpyrazole (DMP) with (CH3)2SnX2 (X = Cl or Br) and (CH3)3SnCl have been characterized by means of i.r. and n.m.r. spectroscopy. The stability constants of the adducts (CH3)2 SnCl2·DMP, (CH3)2SnBr2·DMP and (CH3)3SnCl·DMP in carbon tetrachloride at 19°C have been determined by i.r. measurement of the free monomer DMP concentration.

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.

Mixed allylbutyltin halides (CH2CHCH2)SnBu3-nCln (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, Bu3-nSnClnOC(R′)(R″)CH2CHCH2, 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 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.

New polymeric organotin carboxylates and organostannoxanes have been prepared by reacting R2(CH2CHCH2)2Sn compounds (R = CH3, CH2CH, C6H5) with lactic, glycollic and 2-hydroxy-butyric acid in wateracetone medium. The polymeric nature of these highly insoluble compounds has been inferred from infrared and Mossbauer data.

Compounds of the general formula Ph 4 Sn 2 (OOCR) 2 (R = Et, n-Pr, i-Pr, t-Bu, CH 2 Ph) have been prepared. The IR spectra and molecular weights indicate that these compounds exist in solution as monomeric species with a carboxylate group bridging two tin atoms. The analogous compounds, Ph 4 Sn 2 (OOCMPh 3 ) 2 (M = C, Si and Ge) also appear to be monomeric in solution. The IR spectra of the silicon and germanium derivatives are consistent with the existence of ( d  p )π bonding interaction between the silicon or germanium and carbonyloxygen atoms.

Differential analysis of mixtures of alkylditin compounds, based on their dif ferent rates of reaction toward silver ions, is discussed. Binary mixtures of hexame thyl-, hexaethyl- and hexabutylditin can readily be determined.

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.

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.

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.

The redistribution reactions between R 3 SnMe (R = Me, Et, n–Pr, iso–Pr, Bu) and Me 2 SnCl 2 in methanol, have been investigated. The reactivity order is: Me>Et>n–Pr>Bu>iso–Pr. The second order observed rate constants and the activation parameters are reported. A reaction mechanism involving the electrophilic attack on the carbon centre of the methyl group by the Me 2 Sn 2+ species, assisted by the solvent, is proposed.

Coordination properties of organomercury compounds RHgCl (R = Me, Et, Pr and Ph) have been studied spectrophotometrically in acetonitrile. The stability constants of the halocomplexes RHgCl − 2 have been determined, and are discussed.

The IR spectra in the 2000–400 cm −1 region of 1,1,2,2-tetraphenyl-1,2-diacyloxyditin compounds, Ph 4 Sn 2 (OOCR′) 2 , having R′ = CH 3 , CH 2 Cl, CHCl 2 , CCl 3 or CF 3 have been recorded on the solids, Nujol mulls, and chloroform solutions. Asymmetric and symmetric stretching vibrations of the carboxylic group have been assigned. The frequencies do not change on going from the solids or Nujol mulls to the chloroform solutions in which they are monomeric. The reaction rates of the compounds with iodine in chloroform decrease in the order R = CH 3 > CH 2 Cl > CHCl 2 > CCl 3 >CF 3 . The reaction appears to involve electrophilic attack of iodine at a tin atom. The Ph 4 Sn 2 (OOCR′) 2 compounds are thought in the solid state to be polymers having bridging carboxylate groups and in solution to have carboxylate ligands bridging the two tin atoms, which are thus five-coordinated in a trigonal bipyramidal structure.

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 reaction between pentadeuteriophenyllithium and hexaphenyldilead combined with new measurements of isotopic exchange between Ph6Pb2 (labelled with RaD) and Ph4Pb, have shown that the dilead compound is undissociated in solution. These results cast doubt upon the previously reported equilibrium: Ph6Pb2⇄Ph4Pb+Ph2Pb.

The analytical technique of biamperometric titration, has been utilized to obtain kinetic data in different polar solvents on the reaction, R4Pb + I2 = R3Pb+I− + RI, where R is CH3, C2H5 or n-C3H7.

The structure of the compound Sn(CH3)2Cl2(H2O)2·4C5H4N4 has been determined by single-crystal X-ray diffraction methods. The compound crystallizes in the monoclinic system, space group P21/a, with unit-cell dimensions a= 11.218(4), b= 18.374(5), c= 7.193(3)A, β= 101.9(4)°, and Z= 2. The structure is centrosymmetric at the all-trans Sn(CH3)2Cl2(H2O)2 octahedral units, which are surrounded by four purine molecules hydrogen bonded to the H2O ligands. Each purine also makes hydrogen bonds with purines adjacent to different Sn(CH3)2Cl2(H2O)2 units to form a three-dimensional network. The purine molecules are present in tautomeric pairs: in one isomer a hydrogen atom is attached to the atom N(7) of the imidazole ring, as found in crystals of free purine, and in the other one to the atom N(9). Proton n.m.r. measurements on the system Sn(CH3)2Cl2–purine in acetone show that also in solution direct co-ordination of the base to tin does not occur.

The formation constants for RHgX complexes with R = Me, Et, Pr, and Bu and X = OH, Cl, Br, and I have been determined in water, KNO3 0.1 M at 25°C, by means of a potentiometric technique. Two different stability scales have been found, (1) MeHgX> EtHgX > PrHgX > BuHgX, for X = Cl, Br, OH and (2) MeHgl < EtHgl < PrHgl. Such different behaviour suggests that the softness of RHg+ acids increases on increasing the R chain length.

The structure of the complex Sn(CH3)2Cl2·2C5H5NS has been determined by single-crystal X-ray diffraction methods. The compound crystallizes in the monoclinic system, space group P21/n, with unit-cell dimensions a= 16.793(5), b= 6.201(3), c= 7.882(3)A, β= 90.4(3)°, and Z= 2. The configuration about the tin atom is all-trans octahedral. The C5H5NS ligands are bonded to the metal through the S atom. The observed C(2)–S bond length [1.730(g)A] is consistent with ca. 35% double-bond character, compared to ca. 55% for the uncomplexed ligand. The H atoms on the N atoms are involved in intramolecular hydrogen bonding with the chloride ligands, N–H ⋯ Cl 3.199(9)A. Mass spectra of Sn(CH3)2Cl2·2C5H5NS show that facile elimination of HCl from the complex occurs to give a series of ions containing the ligand C5H4NS; these can be formulated as complexes of the 2-pyridinethiolate anion, probably bonded through the S atom. Mass spectra of the metastable ion [Sn(CH3)Cl(C5H4NS)]+ show that the Sn–L bond strengths are in the order L = methyl < chlorine < 2-pyridinethiolate.

The structure of the complex Sn(CH3)2Cl2·2C5H5NS has been determined by single-crystal X-ray diffraction methods. The compound crystallizes in the monoclinic system, space group P21/n, with unit-cell dimensions a= 16.793(5), b= 6.201(3), c= 7.882(3)A, β= 90.4(3)°, and Z= 2. The configuration about the tin atom is all-trans octahedral. The C5H5NS ligands are bonded to the metal through the S atom. The observed C(2)–S bond length [1.730(g)A] is consistent with ca. 35% double-bond character, compared to ca. 55% for the uncomplexed ligand. The H atoms on the N atoms are involved in intramolecular hydrogen bonding with the chloride ligands, N–H ⋯ Cl 3.199(9)A. Mass spectra of Sn(CH3)2Cl2·2C5H5NS show that facile elimination of HCl from the complex occurs to give a series of ions containing the ligand C5H4NS; these can be formulated as complexes of the 2-pyridinethiolate anion, probably bonded through the S atom. Mass spectra of the metastable ion [Sn(CH3)Cl(C5H4NS)]+ show that the Sn–L bond strengths are in the order L = methyl < chlorine < 2-pyridinethiolate.