Manny Hillman

1,1′-Trimethylenetitanocene dichloride and the corresponding compounds of zirconium and hafnium☆

Abstract The preparation and properties of trimethylene bridged titanocene, zirconocene, and hafnocene dichlorides are described. Additional evidence is presented of correlation between ring-ring angles and differential ring-proton shifts in the PMR spectra.

Bridged Ferrocenes. I

Abstract Previously reported correlations between Mossbauer spectra and the number of bridges in trimethylene bridged ferrocene derivatives have now been observed in the electrode potentials and in the electronic spectra. Crystallographic results reported in the subsequent papers of this series are employed to confirm the previous attribution of these effects to ring—ring tilting, iron-to-ring distance, and to a lesser extent the non-planarity of the rings in some compounds. Rearrangement during the bridging reaction is proposed to explain the failure of the formation of the four-bridged compound.

Mössbauer study of bridged ferrocene derivatives

Abstract The molecular geometry of a series of trimethylene bridged ferrocene derivatives has been studied by means of Mossbauer techniques. The differences in quadrupole splitting and isomer shift among the various derivatives can best be explained as being due to differences in the planarity of the cyclopentadienyl rings.

Bridged ferrocenes: II. The crystal and molecular structure of 1,1′,2,2′,4,4′-tris(trimethylene)ferrocene

Abstract The crystal and molecular structure of 1,1′,2,2′,4,4′-tris(trimethylene)ferrocene has been determined by X-ray diffraction. This compound forms monoclinic needles of space group C2/c with sixteen molecules in the unit cell, a 30.899(6), b 9.416(1), c 25.145(1)Aand β 127.31(1)°. The structure was solved from three-dimensional Patterson and Fourier syntheses and was refined by least squares. The structure consists of two crystallographically independent molecules showing similar geometries. The two cyclopentadienyl rings are eclipsed and the dihedral angle between the two rings, is 2.4°. The average iron to ring-carbon distance is 1.992A. The distance between the rings (3.15A) is significantly shorter than in ferrocene, and the rings appear to be slightly non-planar.

Bridged Ferrocenes : III. The crystal and molecular structure of 1,1′,2,2′,3,4,4′,5′-tetrakis(trimethylene)ferrocene

Abstract The structure of 1,1′,2,2′,3,4,4′,5′-tetrakis(trimethylene)ferrocene has been determined by X-ray diffraction. This compound forms prismatic crystals of monoclinic space group P22/c and four molecules in the unit cell with a 8.649(4), b 21.623(2), c 9.120(1)Aand β 107.21(3)°. The structure was solved from three dimensional Patterson and Fourier synthesis, and was refined by least squares. The two cyclopentadienyl rings are eclipsed and the dihedral angle between the rings is 11.1°. The iron-carbon distances ranged from 1.997(2) to 2.047(2)A.

Formation cross sections for Ca47 using 14.5 MeV neutrons

Abstract The cross sections of the Ti 50 (n, α) Ca 47 and Ca 48 (n, 2n)Ca 47 reactions for 14.5 MeV neutrons, were measured as 10±2 mb and 0.9±0.2 b, in good agreement with the calculated values. The cross sections of the Ti 48 (n, p)Sc 48 and Ti 47 (n, p)Sc 47 reactions were measured incidentally as 55±11 and 99±20 mb, respectively, in fair agreement with some literature values. The cross section obtained for the V 51 (n, α)Sc 48 reaction (18±3 mb) does not agree with results in the literature.

Bridged Ferrocenes: IV. The crystal and molecular structure of 1,1′,2,2′,3,3′,4,5,4′,5′-pentakis(trimethylene)ferrocene

The title compound (molecular formula C 25 H 30 Fe) forms prismatic crystals from hexane which belong to the monoclinic space group P 2 1 / n with lattice constants a 9.486(2), b 12.134(2), c 16.024(2)A, β 93.12(1)°, and Z = 4. The structure was solved by the heavy atom method and refined by full-matrix least squares against 3839 F 2 terms to yield R = 0.08 and R w = 0.12. The Fe to cyclopentadienyl ring-carbon distances range from 1.985(3) to 2.042(4)A. The two cyclopentadienyl rings are eclipsed, they are slightly non-planar, and the angle between their least-squares planes is 12.5°.

Bridged Ferrocenes, V. Moessbauer Spectra - Squeezing the Iron Atom

Abstract New Moessbauer measurements were made for an assortment of bridged ferrocenes containing one tetramethylene or pentamethylene bridge, and ferrocenes containing two bridges, one trimethylene and one tetramethylene, or both tetramethylene. The results for compounds containing four- and five-carbon bridges demonstrate that the trends reported earlier [1] for compounds with only three-carbon bridges were indeed due to strain caused by the short three-carbon bridge. Moessbauer results for four compounds for which the crystal structures had been established show a linear correlation between the change of the iron to ring distances and the change of the Moessbauer parameters. Ring tilt is important only to the extent that it causes the iron to ring distances to change.

Bridged ferrocenes : VII. Synthesis of di- and tri-bridged ferrocenes with pentamethylne chains☆

Abstract Double or successive bridge-enlargement reactions were used on appropriate α-ketones followed by reduction to prepare 1,1′-pentamethyleneferrocene, VIII, 1,1′,3,3′-bis(pentamethylene)ferrocene, XX, and 1,1′,2,2t,4,4′-tris(penta-methylene)ferrocane, XXX. The bridge-enlarging reactions are discussed, and the PMR spectral behavior of the polybridged ferrocenes is briefly discussed.

Production of 52Fe for medical use

Abstract A method is described for producing practical quantities of 52Fe by the 52 Cr ( 3 He , 3n) 52 Fe reaction. The excitation function has been measured for this reaction and a simple chemical separation method has been developed.