Addition of Aldehydes to Germenes: The Influence of Solvent

Abstract

The addition of trans-(2-phenylcyclopropyl)carboxaldehyde to dimesitylfluorenylidenegermane produced four diastereomers of a 1,2-oxagermin, 7aÀd, 2,2,4,4tetramesityl-1,3-dioxadigermetane ( 8), and fluorenylidene-(trans-2-phenylcyclopropyl)methane ( 9). The ratio of the products showed a strong dependence on the solvent: 7aÀd 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.

Synthesis and Reactivity of Acyclic Germanimines: Silyl Rearrangement and Cycloadditions

“…The reactivity observed between germanimine 3 and phenylacetylene is in contrast to the facile Diels–Alder reactivity of [(NON t Bu )­GeNMes] (and Baines’ [(Mes) 2 GeCR 2 ] compound); − with germanimine 3 , there is no evidence of any type of [4 + 2] pathway occurring, either in the isolated products or reaction mixture. To understand the electronic differences in 3 and [(NON t Bu )­GeNMes], density function theoretical (DFT) studies were performed on both 3 and 10 and compared to prior DFT studies on [(NON t Bu )­GeNMes] .…”

“… This contrast in reactivity with the expected 1,2-additions reveals the “ metalloid ” behavior of germanium complexes. Although similar reactivity has been observed with the dimesitylfluorenylidenegermane compound ([(Mes) 2 GeCR 2 ], CR 2 = fluorenylidene), − none of the previously reported reactivity studies of germanimines hinted toward the possibility of this type of [4 + 2] cycloaddition chemistry. Consequently, it was unclear as to whether the [4 + 2] cycloaddition was due to the presence of the NMes group or the dianionic NON t Bu bidentate ligand.…”

Synthesis of the Elusive Branched Fluoro-oligogermane (Ph3Ge)3GeF: A Structural, Spectroscopic, Electrochemical, and Computational Study

“…A survey of the Cambridge Structural Database indicates that crystallographically characterized compounds containing a germanium–fluorine bond are somewhat uncommon, with only ca . 35 hits. − The Ge–F bond in Ph 3 GeF is 1.749(2) Å, and the other Ge–F distances that have been reported for organometallic germanium fluoride compounds range from 1.629(3) Å in ( o -Mes 2 C 6 H 3 ) 2 ­Ge­(H)­F to 1.839(2) Å in (3-Bu t -6-(OMe)­C 6 H 3 ) 3 ­CGeF 3 , although the zwitterionic complex pentafluoro­(4-methyl-1,4-diazonia­cyclohex-1-yl)­methyl­germanate has a Ge–F bond measuring 1.867(2) Å . Of the compounds reported, only [Ag 2 {C 6 H 3 -2,6-(C 6 H 3 -2,6-Pr i 2 ) 2 }­GeGe­(F)­{C 6 H 3 -(C 6 H 3 -2,6-Pr i 2 ) 2 }]­[SbF 6 ] contains a direct germanium–germanium single bond, but this is bridged by two silver atoms .…”

Facile synthesis of luminescent benzo-1,2-dihydrophosphinines from a phosphaalkene

“…24 Analogous [4 + 2] chemistry has been reported for related heavier main group systems: the addition of an aldehyde to a Caryl substituted germene, dimesitylfluorenylidenegermane, gave a 1,2-oxagermin. 25 Interestingly, the fluorenylidene substituent ensures the C-substituted aromatic ring is held coplanar to the GevC bond. There are no reported examples involving an alkyne.…”