Bert Y. Kimura

Solvent effects on the aggregation of lithium bis(trimethylsilyl)amide

Abstract Concentration and temperature dependent 1H and 7Li NMR spectra have been evaluated for lithium bis(trimethylsilyl)amide, LiN[Si(CH3)]32, in ethers and hydrocarbon solvents. The results are interpreted in terms of a monomer-dimer equilibrium in THF and a dimer-tetramer equilibrium in hydrocarbon solvents. Thermodynamic parameters, ΔH0 = −4.0 kcal/mole, ΔS0 = −17 cal · deg−1 · mole−1, obtained for the equilibrium, dimer ⇄ 2 monomer, in THF solutions indicate that the monomer is preferentially solvated in solution. These conclusions are substantiated by isopiestic molecular weight determinations.

1,4 Addition of hexafluorobut-2-yne to co-ordinated cyclo-octa-1,5-diene: crystal structures of the adducts [Rh(acetylacetonato)(C8H12)(C4F6)(1½H2O)] and [Ir(acetylacetonato)(C8H12)(C4F6)2]

Hexafluorobut-2-yne adds 1,4 to co-ordinated cyclo-octa-1,5-diene in the complex [Rh(cod)Cl]2, in contrast to the reaction of hexafluorobut-2-yne with [Ir(acac)(cod)] which gives an iridiacyclopentene ring system.

Homo-Diels–Alder addition of hexafluorobut-2-yne to a norbornadiene rhodium(I) complex: the crystal structure of the adduct [RhCl(norbornadiene)(C4F6)]4

Acetylacetonato(norbornadiene)rhodium(I) reacts with 2 mol. equiv. of hexafluorobut-2-yne to give a complex in which one molecule of the acetylene links the diene to the rhodium via a rhodiacyclopentene ring; however, hexafluorobut-2-yne and chloro(norbornadiene)rhodium(I) dimer give a tetramer, [RhCl(norbornadiene)(C4F6)]4, which is shown by X-ray studies to contain a novel homo-Diels–Alder adduct of the diene and the acetylene.