Synthesis and studies of TIN(II) halides and some adducts by infrared, nuclear magnetic resonance and Mossbauer spectroscopies



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A Mossbauer spectrometer complete with data acquisition and data analysis capabilities based upon an Austin Science Associates Mossbauer spectrometer is described and utilized in the study of tin(II) compounds of the type, SnX[lowered 2] and SnX[lowered 2][dot]2L (X-Cl,Br,I; L=piperidine (pip), triethylenediamine (ten)). The semi-automated synthesis of anhydrous tin(II) chloride and bromide using an apparatus designed to circulate the appropriate hydrogen halide gas over molten tin is described. The syntheses of the above compounds are detailed along with their characterization by melting point, elemental analyses. X-ray powder diffraction patterns and Mossbauer spectral parameters. The decomposition of SnCl[lowered 2], SnI[lowered 2] and SnBr[lowered 2][dot]2(pip) caused by exposure to air was monitored by changes in the Mossbauer spectra. Tin-119 nuclear magnetic resonance (NMR) spectra of SnX[lowered 2] (X=Cl,Br) were obtained at varying concentrations in 1,2-dimethoxyethane (glyme), dimethylformamide (DMF), and dimethylsulfoxide (DMSO). A single resonance was observed for SnI[lowered 2] in DMSO. Linear relationships between concentration and chemical shifts were found. The carbon-13 NMR spectra of SnBr[lowered 2][dot]2(pip) was also obtained. The Mossbauer spectral parameters collected from SnX[lowered 2][dot]2(pip) (X=Cl,Br,I) allowed comparison with the nitrogen-hydrogen stretching frequencies of piperidine. A linear relationship between the change in isomer shift, AIS (=IS[lowered Adduct]-IS[lowered SnX[lowered 2]]), and the change in N-H stretching frequency, [Delta][nu] (=[nu][lowered Adduct]-[nu][lowered piperidine]), indicated a relative Lewis acid strength of SnCl[lowered 2] < SnBr[lowered 2] < SnI[lowered 2] toward piperidine. Extrapolation of the [Delta]IS as a measure of acid strength yields SnCl[lowered 2] [approximately equals] SnBr[lowered 2] < SnI[lowered 2], toward triethylenediamine. A decrease in the quadrupole splitting with an increase in atomic number of the halogen for the dipiperidine adducts was also observed.