Seventeen compounds of the type R3SnAA, where R = methyl (Me) or cyclohexyl (Cyh), and AA is the anion of glycine (gly), DL-a-alanine (ala), DL-a-amino-re-butyric acid (but), DL-a-valine (val), DL-a-leucine (leu), L-a-isoleucine (isoleu), ßalanine ((3-ala), and glycylglycine (glygly), including tri-n-butyltin glycinate (n-Bu3Sn(gly)), have been prepared by azeotropic distillation of water from benzene solutions of the corresponding stannol or bis(trialkyltin) oxide and the acids; DMF is added as a catalyst for R = Me and AA = gly and ala and for n-Bu3Sn(gly). From lowered infrared amino group stretching frequencies and enhanced intensities, twelve of the compounds are identified as amino coordinated to tin, including all the Me3Sn derivatives, n-Bu3Sn(gly), Cyh3Sn(gly), (3-ala, glygly. These compounds, except the last, exhibit Mossbauer QS values in the range 3.2 ± 0.1 mm/sec and ratios of QS to IS generally greater than 2.1, consistent with higher than fourcoordination and pronounced line intensity asymmetry (Goldanskii-Karyagin effect) suggesting associated lattices. Me3Sn-(gly), ala, glygly, and n-Bu3Sn(gly) give ambient-temperature Mossbauer spectra confirming polymeric structures. High v(0-C=0) stretching frequencies, assigned with the aid of deuterated amino group isotopomers, rule out carboxylate carbonyl oxygen coordination to tin in these cases, and infrared and Raman data in the tin-carbon stretching region [v-(Sn-C) is assigned at 490 and 420 cm"1 for the cyclohexyltin group] rule out precisely planar SnC3 skeletons. The aminobridged compounds are depicted as one-dimensional associated lattices of trigonal-bipyramidal units of the axially most electronegative kind. Cyh3Sn(glygly), whose larger QS value and lack of line asymmetry suggest a different structural type, is from lowered infrared stretching frequency evidence coordinated by the amide carbonyl to give six-coordination at tin which from the large QS value must be in the meridian configuration of which no examples are known. Of the five Cyh3Sn derivatives lacking amino-coordination, two (but and val) are, from high v(0-C=0) and reduced QS values, simple, fourcoordinated monomers.The remaining three are higher than four-coordinated from lowered carboxylate stretching frequencies, but QS data rule out axially most electronegative structures. These results are rationalized on the steric effect of the groups at tin and the ce-carbon substituent in the ligand; when both are small, the one-dimensional polymer formed by bridging amino groups is the preferred structure; in intermediate cases carboxylate group coordination, utilizing equatorial or equatorial-axial positions presumably through chelation in monomeric units, becomes preferred; when both are large, only simple, four-coordinated monomers are found. Cyh3SnOH, used for comparison, is shown to be polymeric on the basis of the ambient-temperature Mossbauer spectrum, pronounced line intensity asymmetry, large QS value, and the observation of fragments higher than the molecular ion in the mass spec...
