Cage-Type Hexanuclear Platinum(0) Clusters with
Diphosphine and Isocyanide Ligands Encapsulating Two
Mercury(0) Atoms
Tomoaki Tanase
Eri Goto
Hiroe Takenaka
Takashi Horiuchi
Yasuhiro Yamamoto
Junpei Kuwabara
Kohtaro Osakada
10.1021/om049251x.s001
https://acs.figshare.com/articles/journal_contribution/Cage_Type_Hexanuclear_Platinum_0_Clusters_with_Diphosphine_and_Isocyanide_Ligands_Encapsulating_Two_Mercury_0_Atoms/3304543
Reduction of a mixture containing [PtCl<sub>2</sub>(cod)], aromatic isocyanide (RNC; R = 2,6-xylyl
(Xyl), 2,4,6-mesityl (Mes)), diphosphine (Ph<sub>2</sub>P(CH<sub>2</sub>)<i><sub>n</sub></i>PPh<sub>2</sub>; <i>n</i> = 5 (dpppn), <i>n</i> = 6 (dpphx)),
and NH<sub>4</sub>PF<sub>6</sub> by sodium amalgam (<1%) afforded trigonal-antiprismatic hexanuclear
platinum(0) clusters encapsulating two mercury(0) atoms, [Hg<sub>2</sub>Pt<sub>6</sub>(μ-RNC)<sub>6</sub>(μ-diphos)<sub>3</sub>]
(diphos = dpphx, R = Xyl (<b>6a</b>); diphos = dpppn, R = Xyl (<b>8a</b>), Mes (<b>8b</b>)). Complexes <b>6a</b> and
<b>8a</b> were characterized by X-ray crystallographic analyses to demonstrate that two triangular
platinum(0) units, {Pt<sub>3</sub>(μ-RNC)<sub>3</sub>}, 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 <b>8a</b> (<i>n</i>
= 5), the centroids of the two Pt(0) triangles are linearly arranged with respect to the Hg−Hg axis to form a pseudo-<i>D</i><sub>3</sub>-symmetrical Hg<sub>2</sub>Pt<sub>6</sub> 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
<b>6a</b> (<i>n</i> = 6) the two triplatinum planes glide away from the dimercury axis to lose the <i>D</i><sub>3</sub>
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 Pt<sub>3</sub>Hg<sub>2</sub>Pt<sub>3</sub> cluster frameworks are discussed on the basis of
molecular orbital calculations with EHMO and DFT methods. Hg<sub>2</sub>Pt<sub>6</sub> clusters with an
incomplete open-cage structure, [Hg<sub>2</sub>Pt<sub>6</sub>(μ-RNC)<sub>6</sub>(RNC)<sub>2</sub>(μ-diphos)<sub>2</sub>] (diphos = dpphx, R =
Xyl (<b>7a</b>); diphos = dpppn, R = Mes (<b>9b</b>)), were also isolated as minor products and were
transformed into the closed-cage clusters <b>6a</b> and <b>8b</b> by treatment with an equivalent
diphosphine ligand. By using dppb (<i>n</i> = 4), an open-cage mixed-metal cluster with a single
mercury atom, [HgPt<sub>6</sub>(μ-RNC)<sub>6</sub>(RNC)<sub>2</sub>(μ-dppb)<sub>2</sub>] (R = Xyl (<b>10a</b>), Mes (<b>10b</b>)), was obtained
as the sole product. When the aliphatic isocyanide <i>t-</i>BuNC was used in the reduction with
dpphx, the Hg<sub>2</sub>Pt<sub>6</sub> mixed-metal cluster was not produced, and instead, the PtHgPt trinuclear
complex [HgPt<sub>2</sub>(μ-dpphx)<sub>3</sub>] (<b>11</b>) 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 <b>11</b> are also discussed.
2005-01-17 00:00:00
Hg 2 Pt 6 antiprismatic cluster core
PtCl 2
Isocyanide Ligands Encapsulating
NH 4 PF 6
2.7930 Å
D 3 symmetry
PtHgPt trinuclear
aliphatic isocyanide t
RNC
D 3
diphosphine ligands
methylene chains
trinuclear structure
EHMO
Hg 2 Pt 6 clusters
triplatinum planes
mercury atom
DFT methods
Pt 3 Hg 2 Pt 3 cluster frameworks
n PPh 2
equivalent diphosphine ligand
8 b
dimercury axis