Neutral and cationic germanium(IV) fluoride complexes with phosphine coordination - synthesis, spectroscopy and...

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Inorganic Synthesis

Background:

• Germanium tetrafluoride complexes with phosphine ligands are key intermediates in organogermanium chemistry.
• Understanding the reactivity of these complexes is crucial for developing new synthetic methodologies.
• The influence of ligand bulk and electronic properties on germanium coordination chemistry is an active area of research.

Purpose of the Study:

• To synthesize and characterize novel neutral and ionic germanium(IV) complexes with various phosphine ligands.
• To investigate the reactivity of these germanium(IV) complexes, particularly their response to triflate substitution.
• To explore the potential for reductive defluorination and the formation of germanium(II) species.

Main Methods:

• Synthesis of germanium(IV) complexes via reactions of [GeF4(MeCN)2] with different phosphine ligands.
• Triflate substitution reactions using TMSOTf to generate a series of germanium(IV) triflate complexes.
• Characterization using multinuclear NMR (1H, 19F, 31P), IR spectroscopy, microanalysis, and single-crystal X-ray diffraction.

Main Results:

• Successful synthesis of neutral complexes like trans-[GeF4(PiPr3)2] and [GeF4(κ2-L)].
• Formation of germanium(IV) triflate series [GeF4-n(PMe3)2(OTf)n] and [GeF4-n{o-C6H4(PMe2)2}(OTf)n].
• Observation of unexpected reductive defluorination of trifluoride species, yielding germanium(II) complexes [Ge(PMe3)3][OTf]2 and [Ge{o-C6H4(PMe2)2}(OTf)][OTf].

Conclusions:

• The study demonstrates the versatility of germanium(IV) fluoride complexes in forming diverse neutral and ionic species.
• Reductive defluorination represents a significant reaction pathway for germanium(IV) triflate complexes, leading to Ge(II) species.
• Structural and spectroscopic data provide insights into the coordination environment and bonding in these germanium complexes.