B. Goldfuss et Pv. Schleyer, THE SILOLYL ANION C4H4SIH- IS AROMATIC AND THE LITHIUM SILOLIDE C4H4SIHLI EVEN MORE SO, Organometallics, 14(4), 1995, pp. 1553-1555
The eta(5) coordination of Li+ in lithium silolide Li+(CH)(4)SiH- (4),
increases the delocalization and aromaticity relative to C4H4SiH- (1a
) strongly: 4 exhibits 80% of the stabilization energy of Li+C5H5-, de
creased pyramidality of the silicon center, and increased CC bond leng
th equalization. In addition, delta(Si-29) in 4 is shifted downfield,
delta(C-13) is shifted upfield, and the diamagnetic susceptibility is
exalted (A). Likewise, experimental X-ray data on. pRu(H)[eta(5)-Me(4
)C(4)SiSi(SiMe(3))(3)]}[BPh(4)] (2) and NMR studies on lithium 1-tertb
utyl-2,3,4,5-tetraphenylsilolide (3) suggest delocalized silole rings.