K. C. Molloy

Oxy and thio phosphorus acid derivatives of tin. 5. X-ray crystal and molecular structure of bis(O,O'-diisopropyl dithiophosphato)diphenyltin(IV), a monomeric, molecular, virtual polymer

Abstract : The position of the tin atom was obtained from a Patterson map, and found to lie on the special position 0,0,0 (the crystallographic center of symmetry). The positions of the non-hydrogen light atoms were located by a succession of block-diagonal least squares refinements followed by a difference Fourier synthesis. Subsequent cycles of least-squares refinement allowed the thermal parameters to vary isotropically, initially, and anisotropically in later stages, to yield an R-factor of 0.054 for all data. At this point, correction was made for the anomalous dispersion of tin, and the structure further refined before all non-methyl hydrogen atoms were located from a final difference Fourier synthesis. Refinement was concluded when shifts in all parameters were less than one-third of their corresponding standard deviation. The final R factor was 0.033 for the 2599 reflections included in the least-squares calculations and 0.0522 over all data.

The crystal and molecular structure of trimethyltin(IV) chloride, a chlorine-bridged, linear polymer

Abstract The crystal and molecular structure of trimethyltin(IV) chloride has been determined by the heavy-atom technique, and refined to a final R value of 0.041 for 1375 independent reflections (2θ 2σ(I)) recorded at 138 ± 2 K on a Nonius CAD-4 counter diffractometer. The crystals are monoclinic with space group I2/c; a 12.541(8), b 9.618(11), c 11.015(11) A, β 92.62(7)°, Z = 8, Dcalcd 1.994 g cm−3. The needle crystals are composed of polymeric chains of chlorine atoms bridging non-planar trimethyltin(IV) units at unequal (2.430(2) and 3.269(2) A) distances. The zig-zag chains are bent at chlorine (angle SnCl Sn 150.30(9)°), but nearly linear at tin (angle ClSn Cl 176.85(6)°) to describe a distorted trigonal bipyramidal geometry at tin with the trimethyltin groups eclipsed. The interchain d(Sn Cl) distances are greater than 4.1 A. The angles carbon—tin—carbon (mean 117.1(3)°) are larger than tetrahedral, while the angles carbon—tin—chlorine (mean 99.9(2) A) are smaller, in accord with isovalent hybridization principles, but more severely distorted than in the gas-phase, monomeric structure. The tin—chlorine distance of 2.430(2) A is also longer than in the gas phase monomer, and the intermolecular contact of 3.269 A is shorter than in other organotin chloride bridged systems (sum of Van der Waals radii 3.85 A).

The crystal and molecular structure of trimethyltin chloride at 135 K. A highly volatile organotin polymer

Abstract : Trimethyltin chloride is the key starting material in the laboratory synthesis of the trimethyltin derivatives most subject to study. It is an article of commerce, and has itself been extensively studied by a great variety of spectroscopic and physical methods. There in the literature starting in 1970 a trail of oft referenced private communications which describe a yet unpublished X-ray structure which is incorrect. In addition, the structure of the analogous triphenyltin chloride, which is monomeric at ambient temperature, is said to undergo a change on cooling to a chlorine bridged polymer, but this suggestion is based upon NQR data a 77K which cannot be reproduced. The structure of the homologous trimethyltin fluoride cannot be solved because of disorder, and thus the widely-quoted bridging halide structures for R3SnX compounds are being confirmed here in there case of the title compound for the first time. Solid trimethyltin chloride at 135K is associated through bent chlorine bridges into a one-dimensional polymer containing non-planer C3Sn moieties in a distorted, axially-most electronegative, trigonal bipyramid at tin. (Author)

Variable-Temperature Tin-119m Moessbauer Study of the Chlorodimethyltin (IV) Derivatives of L-Cysteine and DL-Penicillamine.

Abstract : The question of intermolecular association in the chlorodimethyltin (IV) derivatives of L-cysteine (a monohydrate) and DL-penicillamine is settled by variable-temperature tin-119m Mossbauer data between 77 and 140 or 150k, respectively. The slopes of the natural logs of the areas under the resonance are -1.58 + or - 0.1/100/K and -1.46 + or - 0.1/100/K, respectively, considerably lower than those for monomeric lattices. These data rule out an extended association through bridging amino nitrogen atoms or carboxyate oxygen atoms, and suggest a lattice in which small molecular or oligomeric units are associated by an extensive network of hydrogen bonds. An alternative ionic structure of Cl(CH3)2SnSCR2CH(NH3(+))C00- units where R = H can be ruled out on the basis of infrared data (nu(OH)=3450/cm).