John R. Sams

Organotin carboxylates I. Mösssbauer and infrared study of triphenyltin carboxylates and the novel compounds RSn(O)OCOR

Abstract Triphenyltin carboxylates are capable of existing in two forms. The straight-chain compounds are polymeric, with bridging OCO groups and pentacoordinate tin atoms. If the carboxylate chain branches at the α-position the compounds are monomeric and resemble normal esters. The different structures are readily identified from their Mossbauer and infrared spectra. It is shown that at least some of these compounds decompose to yield phenylstannoic carboxylates, which probably exist either as cyclic trimers or linear polymers, with SnOSn bridges and either chelating or ionic carboxyl groups.

Mössbauer and infrared spectroscopic studies of some organotin(IV) schiff base complexes

Several organotin(IV) complexes with quadri- and terdentate anionic Schiff base ligands have been investigated in the solid state using 119Sn Mossbauer and IR spectroscopies, Mossbauer parameters derived from both zero-field and magnetically perturbed spectra suggest that the R2Sn(Salen)(R = Me, Et, Ph) and Me2Sn(Saldap-2OH) complexes have similarly distorted trans-octahedral structures. However, in Ph2Sn(HSaldap-2-O) the ligand appears to be only terdentate, leading to a penta-coordinate structure similar to those of the R2Sn(Sal-N-2-OC6H4) derivatives (R = Me, Ph). For Ph3Sn(Sal-N-2-OC6H4) the asymmetry parameter of the electric field gradient is close to unity, confirming a mer-octahedral configuration for this complex.

Organotin carboxylates II. Mössbauer and infrared study of bonding differences in trimethyltin haloacetates

Abstract Trimethyltin haloacetates are shown to be linear polymers with pentacoordinate tin atoms and bridging OCO groups. The electron density for the Me 3 Sn moiety is independent of variations in the acetato group, although the Mossbauer quadrupole splittings are linear with p K of the corresponding acid. These results are interpreted in terms of changes in the distribution of electron density in the two SnO bonds arising from similar changes in the two CO bonds. The IR data support this suggestion.

Three‐Body Effects in Physical Adsorption

Third‐order interaction data for argon, krypton, xenon, methane, and tetradeuteromethane on the highly graphitized carbon black P33(2700°) are analyzed by means of a two‐dimensional model which specifically includes a term to account for three‐body forces. The intermolecular pair potential in the gas phase is taken to have the Lennard‐Jones (12, 6) form, and when the molecules are adsorbed in a monolayer we assume this potential to be modified by the addition of a repulsive three‐body term proportional to r−3. For a given set of bulk‐gas potential parameters the proportionality constant η in the r−3 term can be uniquely determined from the data, although η is found to be quite sensitive to the exact choice of bulk parameters. Three different theoretical formulas for η give only qualitative agreement with the empirical values. Surface areas determined from the data are insensitive both to the bulk‐phase parameters and to the exact nature of the interaction model. Effective two‐dimensional potential paramet...

Organotin carboxylates IV. Mössbauer and infrared spectra of some triphenyltin haloacetates, and a test of the point-charge model☆

Abstract Mossbauer and infrared spectroscopic techniques show that the compounds Ph 3 SnOCOR (R = CH 3 , CH 2 I, CH 2 Br, CH 2 Cl, CHCl 2 , CF 3 ) are pentacoordinate polymers in the solid state with OCO bridges between the tin atoms. For R = CCl 3 a tetracoordinate monomeric species is obtained. The 119 Sn quadrupole splitting data allow a sensitive test of the predictive ability of the point-charge model, or any other additive model of quadrupole interactions.

Hindered rotation of adsorbed diatomic molecules

Ortho-para separation factors for H2 and D2 are discussed in terms of two models of hindered rotation in the adsorbed phase. Although the available experimental data do not provide a definitive test of the models, it appears that both rotational modes are perturbed, and that a model incorporating hindrance of both modes is capable of fitting both the observed magnitude and temperature dependence of the separation factors.

Organotin carboxylates III. Mössbauer study of tetra- and pentacoordination in branched-chain triphenyltin carboxylates☆

Abstract Branched-chain triphenyltin carboxylates can exist in the solid state either as monomeric species similar in structure to organic esters or as polymeric species with pentacoordinate tin atoms and bridging carboxyl groups. The length and position of the branch are important factors in determining the structural type. A CC bond to the α-carbon atom does not preclude polymerization through OSnO linkages provided the carboxylate group is not bulky. On the other hand, if the group is bulky, the compound is monomeric and conjugation between the CC and the C bonds occurs. No interaction betwee and such vinyl groups and the tin atom is observed.

The magnetic behavior of clusters of the type [M3O(RCOO)6]+. An isotropic model involving dynamic distortions

A dynamic distortion model for the magnetic behavior of clusters which contain equilateral triangles of exchange coupled spins is derived using the assumptions of (i) isotropic coupling and (ii) a linear relationship between the coupling constants and interatomic distances. The model is shown to be consistent with experimental data for complexes of the form [M3O(RCOO)6]+, M=Fe,Cr. The spectrum of magnetic states resulting from the dynamic distortion model is found to be very similar to that of the isoceles triangle model of Kambe, but the present model is physically more satisfactory.

An isotropic exchange model for the magnetic behavior of tetranuclear copper complexes of the type Cu4OX6L4

A theory for the magnetic behavior of distorted tetrahedra of magnetically coupled spin 1/2 atoms is derived using the assumptions of (i) isotropic coupling; and (ii) a linear relationship between the coupling constants and interatomic distances. It is found that the theory provides the basis for a model of the magnetic behavior of complexes of the form Cu4OX6L4 which involves dynamic or fluxional distortions. The new model is found to be in several respects more satisfactory than either the anisotropic or the intercluster exchange models proposed previously.

Preparation, Mössbauer and i.r. spectra of alkyltin(IV) derivatives of dibasic acids

Abstract Tri- and di-methyltin sulfate, selenate and chromate have been synthesized and their structural characteristics have been investigated by i.r. and Mossbauer spectroscopy. Similar studies have also been carried out for the solvated products of the above compounds. From the spectroscopic results it is inferred that in the solid state these compounds possess polymeric structures involving five or six coordinate tin.