Spectroscopic studies for adducts of 2-aminopyrimidine with tin(IV) halides and tin(II) chloride. Cis– trans isomerism in tetrabromobis(2-aminopyrimidine)tin(IV)

Abstract

The complexes [SnCl 4(Apyrim) 2], 1, [SnBr 4(Apyrim) 2], 2 and [SnCl 2(Apyrim)] 2, 3, have been prepared and structurally characterized in the solid state by means of 119Sn Mössbauer spectroscopy, determination of lattice dynamics by temperature-dependent 119Sn Mössbauer spectroscopy, and by vibrational studies. Conductivity measurements and UV spectra in solution are also reported. A cis octahedral structure ( C 2) is proposed for [SnCl 4(Apyrim) 2] while for [SnBr 4(Apyrim) 2] both cis ( C 2) and trans ( C 2 h ) isomers are proposed to be present in the solid state, in an 1:1 molar ratio. An asymmetrically bridged dimer structure is proposed for [SnCl 2(Apyrim)] 2. From the variable-temperature Mössbauer effect, the Debye temperature for 1–3 were determined to be 150, 139 and 117, respectively. A computational study was attempted, utilizing a PM3 Hamiltonian in order to investigate the prevailing isomer of each of the studied species both in the gas phase and in simulated solvent bulk (COSMO model).