LEWIS BASE-FREE PHENYLLITHIUM - DETERMINATION OF THE SOLID-STATE STRUCTURE BY SYNCHROTRON POWDER DIFFRACTION

The solid-state structure of unsolvated, Lewis base-free phenyllithium (LiC6H5) is reported. Structure determination of the simplest lithium aryl was performed by high-resolution synchrotron X-ray powder diffra ction. The structure was solved by ab initio methods in combination wi th difference Fourier analysis and consecutive Rietveld refinements. S olid phenyllithium consists of dimeric Li2Ph2 molecules, which strongl y interact with adjacent Li2Ph2 moieties, forming a polymeric, infinit e-ladder structure along the crystallographic b-axis. In the Li2Ph2 un its the two lithium atoms and the C(ipso) atoms of the two phenyl ring s form an absolutely planar, four-membered ring with the two phenyl ri ngs perpendicular to it. The bonding of the C(ipso) atom to the two Li atoms can be described as a three-center, two-electron bond (Li-C 2.2 4(1) and 2.32(1) Angstrom; Li-C-Li' 63.2(7)degrees). The pi-electrons of the phenyl rings interact strongly with the lithium atoms of neighb oring Li2Ph2 moieties.