Trialkylsilyl-Substituted Silole and Germole Dianions

The synthesis of dipotassio-2,5-bis­(trialkylsilyl)­silacyclopentadienediides K2[3] and germacyclopentadienediides K2[4] is reported. The prepared silole dianions, 3, are characterized by a significantly deshielded silicon nuclei with 29Si NMR signals at very unusual low field positions for silicon anions (δ29Si = 148–169). The results of DFT calculations revealed that this deshielding is a consequence of the silylene-like frontier orbitals of silole dianions 3 and efficient hyperconjugation between the trialkylsilyl-substituents and the cyclic delocalized π-system. Solid-state structure determinations of potassium salts of silole and germole dianions revealed a novel polymeric bis-η5,bis-η1-coordination mode between heterole and potassium ions

Addition of Aldehydes to Germenes: The Influence of Solvent

The addition of trans-(2-phenylcyclopropyl)carboxaldehyde to dimesitylfluorenylidenegermane produced four diastereomers of a 1,2-oxagermin, 7a–d, 2,2,4,4-tetramesityl-1,3-dioxadigermetane (8), and fluorenylidene(trans-2-phenylcyclopropyl)methane (9). The ratio of the products showed a strong dependence on the solvent: 7a–d were formed almost exclusively when ether or benzene was used as the solvent for the reaction, whereas 1,3-dioxadigermetane 8 and alkene 9 were the major products formed in THF. A mechanism is proposed to account for the observations

Addition of Aldehydes to Germenes: The Influence of Solvent

The addition of trans-(2-phenylcyclopropyl)carboxaldehyde to dimesitylfluorenylidenegermane produced four diastereomers of a 1,2-oxagermin, 7a–d, 2,2,4,4-tetramesityl-1,3-dioxadigermetane (8), and fluorenylidene(trans-2-phenylcyclopropyl)methane (9). The ratio of the products showed a strong dependence on the solvent: 7a–d were formed almost exclusively when ether or benzene was used as the solvent for the reaction, whereas 1,3-dioxadigermetane 8 and alkene 9 were the major products formed in THF. A mechanism is proposed to account for the observations

Addition of Aldehydes to Germenes: The Influence of Solvent

The addition of trans-(2-phenylcyclopropyl)carboxaldehyde to dimesitylfluorenylidenegermane produced four diastereomers of a 1,2-oxagermin, 7a–d, 2,2,4,4-tetramesityl-1,3-dioxadigermetane (8), and fluorenylidene(trans-2-phenylcyclopropyl)methane (9). The ratio of the products showed a strong dependence on the solvent: 7a–d were formed almost exclusively when ether or benzene was used as the solvent for the reaction, whereas 1,3-dioxadigermetane 8 and alkene 9 were the major products formed in THF. A mechanism is proposed to account for the observations