Can Low‐Valent Germanium Chemistry Be Practiced Under Ambient Conditions? A Tale of a Water‐Stable Yet Reactive Germylene Monochloride Complex

Abstract

A germylene monochloride complex ((DPM)GeCl, 1) that is water stable was isolated for the first time. Interestingly, it reacts with cesium fluoride under ambient conditions (non-inert atmosphere and water-containing solvent) to afford water stable germylene monofluoride complex ((DPM)GeF, 2). Due to the usage of DPM (dipyrrinate) ligand, germylene monohalides 1 and 2 show fluorescence in the visible region at 555 and 538 nm, respectively. Compounds 1 and 2 are the first fluorescent germylene complexes and were characterized by multinuclear NMR spectroscopy. The structure of compound 1 was also proved by single crystal X-ray diffraction studies.

A Prelude to Biogermylene Chemistry**

“…In the first route, it was synthesized from chlorogermylene 2 that was obtained through the reaction of DPMLi (the lithium salt of dipyrromethene DPMH ( 1 )) with GeCl 2 ⋅(1,4‐dioxane) at −78 °C in toluene (Scheme S1; see SI). Addition of an excess of cesium carbonate dissolved in water to a solution of chlorogermylene DPMGeCl ( 2 ) [11] in dichloromethane (DCM) at room temperature (23 °C) gave germylene 3 as a reddish‐orange solid in 85 % yield (Scheme 1). An excess of the base is essential, and its stoichiometric use leads to an incomplete reaction.…”

“…They have limited solubility in DMSO and are insoluble in aqueous/cell-culture medium. Though a large number of germylenes are known, [6][7][8][9][10][11][12] only two free hydroxygermylenes LGeOH (I) [13a]…”

A Prelude to Biogermylene Chemistry**

“…They have limited solubility in DMSO and are insoluble in aqueous/cell‐culture medium. Though a large number of germylenes are known, [6–12] only two free hydroxygermylenes LGeOH ( I ) [13a] [L=CH{(CMe)(2,6‐ i Pr 2 C 6 H 3 N)} 2 ] and L 1 GeOH ( II ) [13b] [L 1 =(2,6‐ i Pr 2 C 6 H 3 )NC(Ph)C(CH 2 ) 4 CN(2,6‐ i Pr 2 C 6 H 3 )] are known with stability under inert conditions. These aspects highlight the significance of hydroxygermylene 3 that is stable in air, water, and also in the culture medium.…”

A Prelude to Biogermylene Chemistry

“…Though a large number of germylenes are known, [6][7][8][9][10][11] only two free hydroxygermylenes LGeOH (I) [12a]…”

“…(2) [11] in dichloromethane (DCM) at room temperature gave germylene 3 as a reddish-orange solid in 85% yield (Scheme 1) (see the Experimental section in the SI). An excess of the base is essential, and its stoichiometric use leads to an incomplete reaction.…”