Susan M. Grimes

Thermal behaviour, 119Sn Mössbauer and IR spectroscopic studies of some diorganotin(IV)carbohydrates

The synthesis of diorganotincarbohydrates {R2SnL [R = Me, Bu or Oct; L = aldotetrose (erythrose), aldopentoses (arabinose or ribose), ketohexoses (fructose or sorbose), aldohexoses (galactose or glucose) or 6-deoxyaldohexose (rhamnose)]} is reported. Ir and 119Sn Mossbauer spectra are consistent with the presence of tin-carbohydrate oxygen bonds in the compounds and with a trigonal bipyramidal arrangement of two alkyl and three O-containing groups about the tin atoms. The thermal decomposition of the compounds is shown to fall into one of three categories, viz: (1) aldose derivatives that decompose without melting to give SnO as the final tin-containing product, (2) ketose derivatives that decompose without melting to give SnO2 as the final tin-containing product, and (3) aldose derivatives that melt and then decompose to give either SnO or SnO2.

Syntheses, Mössbauer and infrared spectroscopic investigations on tin(II) chloride adducts with purine and pyrimidine bases and nucleosides

Abstract The synthesis of two types of tin(II) complex SnCl2·L·CH3OH (L = adenosine, cytidine and inosine) and SnCl2·L2·CH3OH (L = adenine and cytosine) are described. The complexes are characterised by their infrared and 119Sn Mossbauer data. The Mossbauer shift data suggest that the bonds between tin(II) chloride and the donor atoms of the ligands are relatively weak.

Tin-119 Mössbauer and X-ray crystallographic evidence for differences in the co-ordination of tin in oxalatostannates(II) and malonatostannates(II)

The Mossbauer parameters for the series of oxalatostannates(II) M2Sn(C2O4)2·xH2O are rationalised in terms of distorted square-pyramidal tin environments. The crystal structure of the malonato-complex K2Sn2[CH2(CO2)2]3·H2O is reported: monoclinic, space group P21/n, with a= 11.233(2), b= 18.776(2), c= 8.171 (1)A, β= 90.15(1)°, and Z= 4; R= 0.0277 for 5 805 reflections. Unlike the oxalate groups in the oxalato-complexes, the malonate moieties are bridging rather than chelating and the tin atoms are in trigonal rather than distorted four-pyramidal environments. Mossbauer data are reported for the malonate series of compounds M2Sn2[CH2(CO2)2]3·xH2O (M = NH4, K, Na, Rb, or Cs; x= 0, 1, or 3) and the data for the potassium salt are shown to be consistent with the crystal structure.

Thermal decomposition of inorganic and organometallic compounds of tin. I: Triphenyltin hydroxide

Abstract The thermal decomposition of triphenyltin hydroxide in the temperature range 25–400°C has been studied. The decomposition products formed at each stage have been isolated and characterised. A decomposition scheme involving a reductive-elimination reaction is proposed. The proportions of this reaction and the accompanying reaction are dependent on the mode of heating.

Evidence for the predominance of trigonal pyramidal environments in tin(II) chemistry: The crystal structure of potassium (hydrogen(bismaleato))stannate(II)

Abstract The crystal structure of potassium (hydrogen(bismaleato))stannate(II) is reported. It has unit cell data a = 7.361(12), b = 12.305(3), c = 7.246(8) A, α = 97.02(6)°, β = 109.83(28)°, γ = 87.48(7)°, U = 612.77 A3, Z = 2, Dc = 2.096 g cm−3, Dm = 2.093 g cm −3 and triclinic space group P 1 . The structure consists of layers of discrete [Sn(CHCO2: CHCO2)(CHCO2: CHCO2H)]22− moieties with potassium ions located in holes between the layers. In the discrete unit are two different maleate groups, an anisobidentate maleate ligand and a terminal unidentate monoprotomaleate ligand. The tin atom lies in a trigonal pyramidal environment with three Snue5f8O distances, to the maleate and monoprotomaleate ligands, of 2.199 and 2.212 A respectively. These bonds lengths are consistent with the 119Sn Mossbauer data. The preference for tin to exist in a trigonal pyramidal environment, even in the presence of potential chelating ligands is clearly shown in the structure of this complex tin(II) maleate.

119Sn mössbauer, IR, 1H NMR spectroscopic and thermal decomposition studies on organotin(IV) adducts with glycylglycine

Abstract The complexes R 2 SnCl 2 ·(H 2 glygly), (H 2 glygly = glycylglycine) (R = Me, Bu n , Oct n , Ph) and RSnCl 3 ·(H 2 glygly)

The crystal structure of the ternary tin(II) chalcogenide halide Sn7Br10S2

Abstract The X-ray crystal structure of Sn 7 Br 10 S 2 is reported. Sn 7 Br 10 S 2 is hexagonal with a = b = 12.185, c = 4.418 A, Z = 1. Space group P6 3 . There are three distinct tin sites and each tin atom lies in a partially occupied sixfold generals site of the hexagonal lattice. Two of the sites have tin environments that are typical of tin(II) materials but the third site is unusual. The arrangement of tin atoms in the cell requires the operation of co-operative disorder in the lattice. The anions occupy two sets of general positions in the cell with one set consisting only of Br atoms and the other having randomly distributed Br and S atoms.

Crystal structure of rubidium pentabromodistannate(II)

Abstract The crystal structure of rubidium pentabromodistannate(II) (RbSn2Br5) is determined. The crystals are tetragonal and contain four formula units in a cell of dimensions α = 8.442(2) A, and c = 14.754(3) A with Dc = 4.54 g cm−3, and Dm = 4.44 g cm−3. The structure was solved in the space group I 4 mcm . Unlike NaSn2F5, which contains discrete [Sn2F5]− ions, the structure is a layered lattice consisting of two-dimensional polymeric (Sn2Br5)n−n layer units separated by Rb ions. The Sn and bridging Br atoms lie in planes perpendicular to the c-axis at c = 0 and c = 1 2 . Each Sn atom is surrounded by two bridging Br atoms, at 3.105(1) A, in the plane of the polymer network and by two terminal Br atoms, at 2.755(3) A, symmetrically above and below the network plane. The bridging Br atoms are surrounded by four equatorial Sn atoms and by two axial Rb atoms in the direction of the c-axis at 3.688(1) A. The positions of the non-bonding orbitals on the Sn(II) atoms suggest that the lone pairs could be partly delocalized within the polymeric network. The 119Sn Mossbauer data for RbSn2Br5 are interpreted in the light of its structural data.

The preparation and identification of phases from the tin(II) chloride glycylglycinate system

Abstract Two new distinct products, SnCl 2 ·2(C 4 H 8 N 2 O 3 ) and ClSn(C 4 H 7 N 2 O 3 ) can be obtained from the SnCl 2 : C 4 H 8 N 2 O 3 system. The IR, 119 Sn Mossbauer and thermal analytical data for the products are reported and discussed in terms of the bonding in these compounds.

Novel tin(II) sites in X-ray crystal structures of the tin(II) halide sulphates K3Sn2(SO4)3X (X = Br or Cl)

The crystal structures of K3Sn2(SO4)3X (X = Br or Cl) have been determined by the heavy-atom method and refined by the full-matrix least-squares method to R= 0.0564 for the bromide and 0.0839 for the chloride. The crystals of both compounds are of the hexagonal space group P63(C66, no. 173) with a= 10.256(2), c= 7.582(4)A, and Z= 2 for K3Sn2(SO4)3Br, and a= 10.183(6), c= 7.540(2)A, and Z= 2 for K3Sn2(SO4)3Cl. The structures consist of three-dimensional networks of tin atoms and bridging sulphate groups with discrete potassium and halide ions in holes within the networks. The four tin atoms in the lattices are distributed together with two K+ ions in a six-fold general position and have three oxygen atoms at unusually long distances of 2.47, 2.57, and 2.63 A for the bromide and 2.45, 2.55, and 2.56 A for the chloride. The shortest tin–halogen contacts are 2.97 A for the chloride and 3.13 A for the bromide. The halide ion is surrounded in a distorted octahedron by tin(II) or potassium atoms. The arrangement of tin atoms, taken along with 119Sn Mossbauer data and the lengths of the Sn–O bonds in the structures, is consistent with cluster formation in which lone-pair electron density on the tin atoms is delocalised in cluster molecular orbitals.