om049251x_si_001.pdf (58.38 kB)
Cage-Type Hexanuclear Platinum(0) Clusters with Diphosphine and Isocyanide Ligands Encapsulating Two Mercury(0) Atoms
journal contribution
posted on 2005-01-17, 00:00 authored by Tomoaki Tanase, Eri Goto, Hiroe Takenaka, Takashi Horiuchi, Yasuhiro Yamamoto, Junpei Kuwabara, Kohtaro OsakadaReduction of a mixture containing [PtCl2(cod)], aromatic isocyanide (RNC; R = 2,6-xylyl
(Xyl), 2,4,6-mesityl (Mes)), diphosphine (Ph2P(CH2)nPPh2; n = 5 (dpppn), n = 6 (dpphx)),
and NH4PF6 by sodium amalgam (<1%) afforded trigonal-antiprismatic hexanuclear
platinum(0) clusters encapsulating two mercury(0) atoms, [Hg2Pt6(μ-RNC)6(μ-diphos)3]
(diphos = dpphx, R = Xyl (6a); diphos = dpppn, R = Xyl (8a), Mes (8b)). Complexes 6a and
8a were characterized by X-ray crystallographic analyses to demonstrate that two triangular
platinum(0) units, {Pt3(μ-RNC)3}, are connected by three diphosphine ligands with long
methylene chains to form a closed cage of the cluster-based metallocryptand, in which two
mercury(0) atoms are incarcerated with a notably short Hg−Hg distance. In complex 8a (n
= 5), the centroids of the two Pt(0) triangles are linearly arranged with respect to the Hg−Hg axis to form a pseudo-D3-symmetrical Hg2Pt6 antiprismatic cluster core (average Pt−Pt
= 2.6719 Å, average Pt−Hg = 2.9417 Å, and Hg−Hg = 2.8424(2) Å). In contrast, in complex
6a (n = 6) the two triplatinum planes glide away from the dimercury axis to lose the D3
symmetry (average Pt−Pt = 2.639 Å, average Pt−Hg = 2.923 Å, and Hg−Hg = 2.826(2) Å).
The electronic structures of the Pt3Hg2Pt3 cluster frameworks are discussed on the basis of
molecular orbital calculations with EHMO and DFT methods. Hg2Pt6 clusters with an
incomplete open-cage structure, [Hg2Pt6(μ-RNC)6(RNC)2(μ-diphos)2] (diphos = dpphx, R =
Xyl (7a); diphos = dpppn, R = Mes (9b)), were also isolated as minor products and were
transformed into the closed-cage clusters 6a and 8b by treatment with an equivalent
diphosphine ligand. By using dppb (n = 4), an open-cage mixed-metal cluster with a single
mercury atom, [HgPt6(μ-RNC)6(RNC)2(μ-dppb)2] (R = Xyl (10a), Mes (10b)), was obtained
as the sole product. When the aliphatic isocyanide t-BuNC was used in the reduction with
dpphx, the Hg2Pt6 mixed-metal cluster was not produced, and instead, the PtHgPt trinuclear
complex [HgPt2(μ-dpphx)3] (11) was obtained in a low yield and was characterized by X-ray
crystallography to demonstrate the linear trinuclear structure with a considerable attractive
Pt−Hg interaction (average Pt−Hg = 2.7930 Å and Pt−Hg−Pt = 179.591(3)°). The electronic
structures of 11 are also discussed.
History
Usage metrics
Categories
Keywords
Hg 2 Pt 6 antiprismatic cluster corePtCl 2Isocyanide Ligands EncapsulatingNH 4 PF 62.7930 ÅD 3 symmetryPtHgPt trinuclearaliphatic isocyanide tRNCD 3diphosphine ligandsmethylene chainstrinuclear structureEHMOHg 2 Pt 6 clusterstriplatinum planesmercury atomDFT methodsPt 3 Hg 2 Pt 3 cluster frameworksn PPh 2equivalent diphosphine ligand8 bdimercury axis
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC