Neutral and cationic main group element cages of germanium(II) withpyrazolyl ligands: solid state structures, DFT calculations and advancedsolution NMR investigations

摘要

Two equivalents of 3,5-bis(trifluoromethyl)pyrazole or 5-methyl-3-(trifluoromethyl)pyrazole react with[Ge{N(SiMe_3)_2}_2] to give dimeric homoleptic germanium(II) compounds [{Ge(3,5-RR′pz)_3}_2](R = R′ = CF_3(1); R = Me, R′ = CF_3(2)), which provide cationic triply pz-bridged cages of thegeneral formula [Ge(μ_2-3,5-RR′pz)_3Ge]~+[OTf]~-(R = R′= CF_3(3); R = Me, R′ = CF_3(4)) upontreatment with one equivalent of triflic acid (HOTf, HSO_3CF_3). The compounds were studied using thepulsed field gradient spin-echo (PGSE) NMR technique and ~(19)F,~1H-HOESY NMR methods. Singlecrystal X-ray structure determinations of all compounds are reported. The results obtained are verifiedby density functional theory calculations.