Chapter 2. Alkali and alkaline earth metals

Abstract

ion;g the use of lithium compounds in medicine;" the structural chemistry of organonitrogen-lithium compounds;" the use of tmeda as a ligand for lithium;', the solution structures of lithium dialkylamidesl and their uses as reducing agents', have appeared.The ground state electronic structure and stability of H', Li', and Na' and hydrogen and alkali metal halides have been calculated using high level ab initio methods. The H', Li', and Na+ affinities of hydrogen and the alkali metal halides were calculated and the K', Rb+, and Cs' affinities predicted. Trends in electronic structure and stability were rationalized in terms of charge transfer and bond indices. 'Carbon-donor Ligands.-The reaction of CpLi with [PPh,]Cl has been shown to give [PPh,][Cp,Li],the anion of which contains two q5 staggered rings.I6 Lithium isodicyclopentadienide has been found to react with BrCH,CD,Cl, Me,SiCl, and FeCl, with little or no facial stereoselectivity. It was monomeric at room temperature and in a monomer/dimer mixture at low temperature. MNDO calculations were also r e p ~r t e d . ' ~ Two forms of this compound (isodiCp) have been prepared and structurally characterized as (tmeda)Li[q'-isodiCp] and ,][Li(q5-isodiCp),].' The compound Li[(Me,C,NAlMe,),(p-Cl)] has been prepared by the reaction of Me,AlCl with 2,3,4,5-tetramethylpyrrole and LiBu". Lithium was sandwiched between the two pyrrole ring^.'^ A simple route to phosphindolyl lithium complexes via reaction of LiRPH (R = Ph, 2,4,6-Bu',C6H,) with Ph,C, has been published. The lithium was found to be q5-and q3-coordinated to the PC, ring in the two molecules in the unit cell.,'The crystal structure of Li2C,Ph,.2dme has been reported. The compound is monomeric with the lithium ions coordinating on opposite sides of the cis C, backbone and most strongly to the terminal carbons.,' Mixed metallation of toluene in the presence of tmeda gave the benzyl complex [(PhCH,),Li, -,Na2 +,(tmeda),] containing an eight-membered ring. The coordination at lithium was expanded due to the presence of the nearby larger sodium atom.,, The crystal structure of (PriLi)6 has been reported. The lithium atoms formed an octahedron, six faces of which are capped with an isopropyl ligand.23 The 1,3 and 1,4 dilithiobenzenes have been isolated for the first time from the corresponding i o d ~b e n z e n e s . ~~ Several ally1 and benzyl lithium compounds have been prepared by lithium-tellurium exchange reactions of allylic and 9 i n 11 12