Host–guest chemistry of the cluster [Hg3(µ-dppm)3]4+ [dppm = bis(diphenylphosphino)methane] with oxo- and fluoro-anions
The subvalent mercury clusters Hg3(µ-dppm)3(SiF6)2 and Hg3(µ-dppm)3(PF6)4 with weakly co-ordinating octahedral fluoro-anions have been prepared from HgO, H2SiF6 or HPF6, dppm and elemental mercury. The solid state structures of these clusters were determined by single crystal X-ray structure analysis as well as those of Hg3(µ-dppm)3(O3SCF3)4, Hg3(µ-dppm)3(O3SCF3)4·MeOH, Hg3(µ-dppm)3(O3SCH3)4 and Hg3(µ-dppm)3(O3SCH3)4·4H2O. The [Hg3(µ-dppm)3] clusters are bifunctional recognition hosts and two anions of all the clusters are found inside the two cavities formed by the 12 phenyl groups of the dppm ligands and the Hg3 triangle. The anion dependence of the 31P NMR shift of the clusters is attributed to a varying occupancy of the cavities in solution.