Concerning the Structure of Trimethyltin Fluoride

Abstract

The structure and the nature of the bonds in trimethyltin fluoride are discussed on the basis of the infrared and the Raman spectra with reference to the results of the X-ray diffraction study by Clark et al. and a few additional X-ray data obtained on the fluoride and related trimethyltin compounds. The most reasonable structure is one in which the planar trimethyltin group is bridged by the fluorine atom forming a non-linear unsymmetrical Sn-F…Sn bond. The distorted bipyramidal configuration around the tin atom can be explained in terms of involvement of the d-orbitals of the tin atom in the bonding.

The structure of trimethyltin fluoride

“…2 Trimethyltin fluoride is insoluble in most organic solvents except in hot alcohols and melts upon decomposition at a relatively high temperature (375°C), which is strongly indicative of its aggregation in the solid state. 4 The second disorder model was also rejected upon careful reevaluation of the single crystal X-ray diffraction data which did not exhibit diffraction spots indicative of doubling in one cell axis, which is to be expected in the case of alternate tilting in successive Sn(CH 3 ) 3 groups. Clark et al reported that disorder precluded the proper refinement of its structure.…”

“…Trimethyltin fluoride was the first triorganyltin fluoride to be studied by X-ray crystallography; 3 however, the structural characterization proved to be problematic. 4 Hence, it was necessary to propose a new model with parallel planar SnC 3 moieties and positional disorder in the fluorine atoms with asymmetric fluorine bridges (Sn-F: 2.15 Å, Sn⋯F: 2.45 Å) and Sn-F⋯Sn and F-Sn⋯F angles of 141°. 3 Two possible disorder models were put forward, both invoking fluorine-bridged chain motifs.…”

“…The observation of one SnC 3 stretching band in the infrared spectrum (550 cm −1 , ν as ) and two SnC 3 stretching bands in the Raman spectrum (517 cm −1 , ν s and 556 cm −1 , ν as ) was found to be more congruent with a planar SnC 3 arrangement, providing evidence against the first disorder model. 4 The second disorder model was also rejected upon careful reevaluation of the single crystal X-ray diffraction data which did not exhibit diffraction spots indicative of doubling in one cell axis, which is to be expected in the case of alternate tilting in successive Sn(CH 3 ) 3 groups. 4 Hence, it was necessary to propose a new model with parallel planar SnC 3 moieties and positional disorder in the fluorine atoms with asymmetric fluorine bridges (Sn-F: 2.15 Å, Sn⋯F: 2.45 Å) and Sn-F⋯Sn and F-Sn⋯F angles of 141°.…”

“…4 The second disorder model was also rejected upon careful reevaluation of the single crystal X-ray diffraction data which did not exhibit diffraction spots indicative of doubling in one cell axis, which is to be expected in the case of alternate tilting in successive Sn(CH 3 ) 3 groups. 4 Hence, it was necessary to propose a new model with parallel planar SnC 3 moieties and positional disorder in the fluorine atoms with asymmetric fluorine bridges (Sn-F: 2.15 Å, Sn⋯F: 2.45 Å) and Sn-F⋯Sn and F-Sn⋯F angles of 141°.…”

Methyl Tin(IV) Derivatives of HOTeF5 and HN(SO2CF3)2: A Solution Multinuclear NMR Study and the X-ray Crystal Structures of (CH3)2SnCl(OTeF5) and [(CH3)3Sn(H2O)2][N(SO2CF3)2]

“…The bridging occurs through halogen atoms or the oxoacid ligands. In the solid state, methyl tin halides (CH 3 ) 3 SnF , and (CH 3 ) 3 SnCl form extended halogen-bridged chains with pentacoordinate tin, while (CH 3 ) 2 SnF 2 has a sheetlike polymeric structure with hexacoordinate tin . The crystal structures of (CH 3 ) 2 Sn(SO 3 F) 2 , (CH 3 ) 3 SnOOCCF 3 , (C 6 H 12 ) 3 SnOOCC 3 H 7 , and (CH 3 ) 2 SnCl(OOCCH 3 ) 13 contain tin centers that are bridged by the oxoacid ligands.…”