Michael A. Weiner

The Preparation of Organolithium Compounds by the Transmetalation Reaction. I. Vinyllithium1,2

The transmetalation reaction occurring between phenyllithium and tetravinyltin (4: 1 molar ratio) in ether produces vinyllithium in good yield. A similar reaction occurs between n-butyllithium and tetravinyltin in pentane; in this case solid vinyllithium precipitates. Vinyllithium is more stable in ether and tetrahydrofuran solution than are nbutyllithium or phenyllithium. The use of vinyllithium in the preparation of a number of previously known vinyl compounds, as well as of the new STAB(CH = CH/sub 2/)/sub 4/!/sup -/ and STAB(CH ~ CH/sub 2/ ) (C/sub 6/H/sub 5/)/sub 3/!/sup -/ ions, is described. (auth)

Ultraviolet photoelectron spectra of 4-substituted pyridine-pentacarbonylchromium complexes

Abstract The ultraviolet photoelectron spectra of Cr(CO) 5 (4-RPyr) have been measured, and the IPs observed below 12 eV are discussed. Bands found in the region 7-8 eV are assigned to ionization from the chromium d orbitals. The IP values are shown to increase with the increasing electron acceptor nature of the ring substituents. The remaining bands below 12 eV are assigned to the pyridine orbitals. The IP values of the uncomplexed pyridines are observed to increase upon complexation, and a comparison is made of the effects of complexation with the Cr(CO) 5 and BH 3 moieties.

Measurements of pKa and hydrogen-bond strengths of some organosilicon- and organogermanium-substituted pyridine N-oxides

Abstract The results of p K a measurements on 4-substituted pyridine N -oxides show that organosilicon and organogermanium substituents are responsible for a decreased basicity relative to the tert-butyl derivative and the unsubstituted compound. No such effect is shown in the 3-substituted compounds. The results of hydrogen-bonding studies on the 4-substituted pyridine N -oxides (using methanol and phenol as acids) show that the organometallic substituents are responsible for a decreased basicity relative to the tert-butyl derivative, but not when compared to the unsubstituted compound. The effect of changing experimental conditions on the nature of the pyridine N -oxide moeity is discussed.