The complexes [triangulo-Hg3(μ-dppm)3Xn](4−n)+ (X=Cl, Br and I, n=1, 2) are formed in a small extent upon addition of halides to the cationic subvalent cluster [triangulo-Hg3(μ-dppm)3]4+, whereas SeCN− and CN− cause quantitative fragmentation. The cluster [triangulo-Hg3(μ-dppm)3(SCN)2]2+ is produced either by the reaction of [triangulo-Hg3(μ-dppm)3]4+ with thiocyanate or via reduction of a mixture of Hg(SCN)2, [Hg(Me2SO)6](O3SCF3)2 and 3 mequiv. of dppm with elemental mercury. The X-ray structure of [Hg3(μ-dppm)3(SCN)2](O3SCF3)2 shows a Hg3 triangle (Hg–Hg distances 286.60(14), 279.32(12) and 281.2(2) pm) spanned by three dppm ligands. The thiocyanate ions are positioned nearly parallel to the Hg3 plane in the two cavities formed by the Hg3 group at the bottom and the phenyl groups of the dppm ligands as the walls (Hg1–S1 277.5(6) and Hg3–S2 278.4(6) pm). Phosphorus-31 solution NMR indicates a rapid rotation of the SCN− ligands about the Hg3 triangle within the cavity.

Subvalent mercury clusters [Hg-3(LL)(3)](4+), with LL = dpam (dpam = Ph2AsCH2AsPh2) or Ph2AsCH2PPh2 and dpam-dppm (dppm = Ph2PCH2PPh2) or dpam-Ph2AsCH2PPh2 mixed ligand complexes were obtained by reaction of [Hg-2](2+) with the ligands or by reduction of a mixture of [Hg(Me2SO)(6)](O3SCF3)(2) and the ligands with elemental mercury. Whereas the equilibrium 2Hg(2+) + Hg <-> [Hg-3](4+) is far to the right in the presence of the ligands dpam or dppm, only ca. 20% conversion is observed for Ph2AsCH2PPh2. The clusters are characterized by FAB MS and multinuclear NMR spectroscopy. The Hg-199-Hg-199 coupling constants of [Hg-3(mu-dpam)(2)(mu-dppm)](O3SCF3)(4) have values of 17800 and 23600 Hz. The fragmentation of [Hg-3(mu-dpam)(3)](O3SCH3)(4) gives [Hg-2(mu-dpam)(2)](O3SCH3)(4) which is characterized by single-crystal X-ray diffraction. (C) 2000 Elsevier Science S.A. All rights reserved.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

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.