Brian W. Fitzsimmons

The Mössbauer effect and chemistry. Part III. Six-co-ordinate complexes of tin(IV) containing tin–carbon bonds

Octahedral complexes of tin(IV) containing one and two tin–carbon bonds have been synthesised and examined by means of Mossbauer spectroscopy. The quadrupole splittings of compounds with two Sn–C bonds depend upon the geometry of the C–Sn–C unit. cis-R2SnX4 complexes have quadrupole splittings of ca. 2 mm. sec.–1 whilst trans-complexes have splittings of ca. 4 mm. sec.–1. A compound with one Sn–C bond has a quadrupole splitting approximately equal to that of a complex with two cis-Sn–C bonds. In this way stereochemical assignments are made for a number of these complexes and the results are discussed.

The Mössbauer effect and chemistry. Part I. Spectra of octahedral cis–trans-isomers and related compounds

The Mossbauer spectra of a series of low-spin octahedral cis–trans-isomers of iron(II) have been measured, and the results rationalised using the general expression for electric field gradients. Part of the series is made up of some new ethyl isocyanide complexes, and the study includes derivatives of formula [Fe(CN)(CNR)5]+. The cis–trans isomerism reported for dicyanobis-(1,10-phenanthroline)iron(II) is discussed.

The Mössbauer effect and chemistry. Part IV. Some further work on the stereochemistry of organotin complexes and results for organotin dithiocarbamates

Mossbauer parameters have been measured for a series of diorganotin bisdithiocarbamates and interpreted in terms of cis-octahedral structures for Ph2Sn[S2CNR2]2 and trans-octahedral structures for R12Sn[S2CNR22]2. Factors affecting the stereochemistry of organotin hexaco-ordinate complexes are discussed.

The Mössbauer effect and chemistry. Part II. Complexes of iron(II) and iron(III) with 1,2-di(salicylideneamino)ethane, 1,10-phenanthroline, and related compounds

Mossbauer spectra of the compounds Fe phenCl3 and Fe2phen3Cl6(phen = 1,10-phenanthroline) are reported, and structures for these compounds advanced. Data are presented for the binuclear compounds [phen2FeCl(O)ClFe phen2]Cl2,4H2O and [Fe salen]2O [salen = 1,2-di(salicylideneamino)ethane] and shown to be consistent with the presence of octahedrally co-ordinated Fe(iii) with S= 5/2. Large quadrupole splitting are found for the compounds [Fe phen3](ClO4)3 and [Fe bipy3](ClO4)3(bipy = bipyridyl). The chemical isomer shifts are additive for the series of compounds K4[FeII(CN)6],3H2O, K2[FeII(CN)4phen],FeII(CN)2phen2, and [FeIIphen3](ClO4)2. Tripyridylamine (tripam) forms complexes [FeIItripam2](ClO4)2 with S= 0 and [FeIItripam2][FeCl4] with S= 0 for the cation and S= 2 for the anion. A similar compound is formed with Fe(II) and biacetyl dihydrazone (Bdh).

The Mössbauer effect and chemistry. Part V. Spectra of some triorganotin compounds

Mossbauer spectral data for the 119Sn nuclei in a range of triorganotin compounds are given. The quadrupole splittings are compared with those of triorganotin compounds of known crystal structure. A range of quadrupole splitting for tetrahedral triorganotin compounds is suggested.

Mössbauer spectrum of dichlorodimethylbis(pyridine N-oxide)tin(IV) in an externally applied magnetic field

The sign of the quadrupolar interaction has been found to be positive for a six-co-ordinate organotin(IV) complex of known crystal structure, namely Me2SnCl2(C5H5NO)2. Taking the value of the quadrupole moment for the l =3//2 nuclear state of 119Sn to be –8 × 10–26 cm2, Vzz for this compound is negative.