Host-guest interactions of the cluster [triangulo-Hg-3(mu-dppm)(3)](4+) (dppm = bis(diphenylphosphino)methane) with halides and pseudohalides

The complexes [triangulo-Hg-3(mu-dppm)(3)X-n]((4-n)+) (X = Cl, Br and I, n = 1, 2) are formed in a small extent upon addition of halides to the cation ic subvalent cluster [triangulo-Hg-3(mu-dppm)(3)](4+), whereas SeCN- and CN - cause quantitative fragmentation. The cluster [triangulo-Hg-3(mu-dppm)(3) (SCN)(2)](2+) is produced either by the reaction of [rriangulo-Hg-3(mu-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 [Hg-3(mu-dppm)(3)(SCN)(2)] (O3SCF3)(2) shows a Hg-3 triang le (Hg-Hg distances 286.60(14), 279.32(12) and 281.2(2) pm) spanned by thre e dppm ligands. The thiocyanate ions are positioned nearly parallel to the Hg-3 plane in the two cavities formed by the Hg-3 group at the bottom and t he 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 t he SCN- ligands about the Hg-3 triangle within the cavity. (C) 2000 Elsevie r Science Ltd All rights reserved.