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

The neutral complexes -[GeF(PPr)] and [GeF(κ-L)] (L = CHC(CHPPh) or P(CHCHPPh)) are obtained from [GeF(MeCN)] and the ligand in CHCl. Treatment of [GeF(PMe)] with n equivalents of TMSOTf (MeSiOSCF) leads to formation of the series [GeF(PMe)(OTf)] ( = 1, 2, 3), each of which contains six-coordinate Ge(IV) with PMe ligands and X-ray structural data confirm that the OTf groups interact with Ge(IV) to varying degrees. Unexpectedly, [GeF(PMe)(OTf)] undergoes reductive defluorination in solution, forming the Ge(II) complex, [Ge(PMe)][OTf] (and [FPMe]). The bulkier PPr leads to formation of the ionic [GeF(PrP)][OTf], containing a [GeF(PrP)] cation. [GeF{-CH(PMe)}], containing the -chelating diphosphine, also reacts with n equivalents of TMSOTf to generate [GeF{-CH(PMe)}(OTf)] ( = 1, 2, 3). As for the PMe system, the trifluoride, [GeF{-CH(PMe)}(OTf)], is unstable to reductive defluorination in solution, producing the pyramidal Ge(II) complex [Ge{(-CH(PMe)}(OTf)][OTf], whose crystal structure has been determined. The [GeF{PhP(CH)PPh}(OTf)] and [GeF{PhP(CH)PPh}(OTf)], obtained similarly from the parent tetrafluoride complex, are poorly soluble, however their structures were confirmed crystallographically. The complexes in this work have been characterised variable temperature H, F{H} and P{H} 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.