Synthesis, characterization, and reactivity of an N-heterocyclic germanium(II) hydride: reversible hydrogermylation of a phosphaalkyne

Sam Lim Choong, William Woodul, Christian Schenk, Andreas Stasch, Anne Richards, Cameron Jones

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Abstract

The beta-diketiminato germanium(II) chloride complex [((But)MesNacnac)GeCl] ((But)MesNacnac = [ N(Mes) C(Bu(t)) (2)CH](-) Mes = mesityl) has been prepared and spectroscopically characterized. Treating this compound and a less bulky system, [((Me)MesNacnac)GeCl] ((Me)MesNacnac = [ N-(Mes)C(Me) (2)CH(-)), with K[HBEt(3)] led to differing outcomes, namely, the formation of the novel diamido germylene [((But)MesNacnacH)Ge:] ((But)MesNacnacH = [N(Mes)C(H) (Bu(t))C(H)C(Bu(t))N(Mes)](2-)) and the germanium(II) hydride [((Me)MesNacnac)GeH], both of which were crystallographically characterized. The former product forms via a 1,3-hydrogen migration reaction involving [((But)MesNacnac)GeH] as an unstable reaction intermediate. Reactions of [((Me)MesNacnac)GeH] with CO(2) and P CBu(t) proceed at or below ambient temperature, in the absence of a catalyst, to give the crystallographically characterized hydrogermylation products [((Me)MesNacnac)GeOC(=O)H] and [((Me)MesNacnac)GeC(Bu(t))=PH], with complete regioselectivity. When a solution of the latter was gently heated, the hydrogermylation reaction was partially reversed, regenerating [((Me)MesNacnac)GeH] and P CBu(t). Heating to higher temperatures led to the irreversible isomerization of [((Me)MesNacnac)GeC(Bu(t))=PH] to (E)-[((Me)MesNacnac)GeP=C(H)(Bu(t)], theoretical studies of which indicate is the thermodynamic product of the original hydrogermylation reaction.
Original languageEnglish
Pages (from-to)5543 - 5550
Number of pages8
JournalOrganometallics
Volume30
Issue number20
DOIs
Publication statusPublished - 2011

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