New High Nuclearity Platinum−Ruthenium Carbonyl Cluster Complexes Containing a Phenylacetylene Ligand: Structures and Properties

Reaction of the mixed-metal carbonyl cluster complex Ru5(CO)15(C)[Pt(PBut3)], 3, with
PhC2H yielded the new compound PtRu5(CO)13(PBut3)(μ5-C)(μ3-PhC2H), 4, in 41% yield. Two
new bimetallic cluster complexes, Pt2Ru5(CO)13(PBut3)2(μ5-C)(μ3-PhC2H), 5, and Pt3Ru5(CO)13(PBut3)3(μ5-C)(μ3-PhC2H), 6, were subsequently obtained in 44% and 40% yield, respectively,
from the reaction of 4 with an excess of Pt(PBut3)2. All products were characterized
crystallographically by single-crystal X-ray diffraction techniques. The structure of 4 consists
of a square-pyramidal cluster of five ruthenium atoms with a Pt(PBut3) group capping one
of the Ru3 triangles. A PhC2H ligand bridges one of the PtRu2 triangles. Compounds 5 and
6 are similar to 4 but have in addition one and two Pt(PBut3) groups bridging one and two
edges of the Ru5 square-pyramidal portion of the cluster. Compound 6 was shown to be
dynamically active on the 31P NMR time scale by a process that involves an interchange of
two of its inequivalent Pt(PBut3) groups.