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

The neutral complexes trans-[GeF4((PPr3)-Pr-i)(2)] and [GeF4(kappa(2)-L)] (L = CH3C(CH2PPh2)(3) or P(CH2CH2PPh2)(3)) are obtained from [GeF4(MeCN)(2)] and the ligand in CH2Cl2. Treatment of [GeF4(PMe3)(2)] with n equivalents of TMSOTf (Me3SiO3SCF3) leads to formation of the series [GeF4-n(PMe3)(2)(OTf)(n)] (n = 1, 2, 3), each of which contains six-coordinate Ge(IV) with trans PMe3 ligands and X-ray structural data confirm that the OTf groups interact with Ge(IV) to varying degrees. Unexpectedly, [GeF3(PMe3)(2)(OTf)] undergoes reductive defluorination in solution, forming the Ge(II) complex, [Ge(PMe3)(3)][OTf](2) (and [FPMe3](+)). The bulkier (PPr3)-Pr-i leads to formation of the ionic [GeF3((Pr3P)-Pr-i)(2)][OTf], containing a [GeF3((Pr3P)-Pr-i)(2)](+) cation. [GeF4{o-C6H4(PMe2}(2))], containing the cis-chelating diphosphine, also reacts with n equivalents of TMSOTf to generate [GeF4-n{o-C6H4(PMe2)(2)}(OTf)(n)] (n = 1, 2, 3). As for the PMe3 system, the trifluoride, [GeF3{o-C6H4(PMe2)(2)}(OTf)], is unstable to reductive defluorination in solution, producing the pyramidal Ge(II) complex (Ge{(o-C6H4(PMe2)(2)}(OTf)][OTf], whose crystal structure has been determined. The [GeF3{Ph2P(CH2)(2)PPh2}(OTf)] and [GeF2{Ph2P(CH2)(2)PPh2}(OTf )(2)], obtained similarly from the parent tetrafluoride complex, are poorly soluble, however their structures were confirmed crystallographically. The complexes in this work have been characterised via variable temperature H-1, F-19{H-1} and P-31{H-1} NMR studies in solution, IR spectroscopy and microanalysis and through single crystal X-ray analysis of representative examples across each series. Trends in the NMR and structural parameters are also discussed.

Automated summary

The translation describes the formation and reactions of various germanium complexes with different ligands. The characterization of these complexes was done through various spectroscopic and crystallographic methods. Trends in NMR and structural parameters were also discussed.