Triangular Platinum(II) Cluster Complexes and Cluster Core Transformation from Square-Planar to Triangular Type

• Published in: Bulletin of the Chemical Society of Japan 2000-04, Vol.73 (4), p.775-784
• Main Authors: Yamaguchi, Tadashi, Nishimura, Nozomu, Shirakura, Ken-ichi, Ito, Tasuku
• Format: Article
• Language: English
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.73.775

Reactions of [PtII4(μ-CH3COO)8] (1) with dioximes or with N,N′-dimethylethylenediamine induced a cluster core transformation from a square planar to a triangular type to afford PtII3 clusters. Three of these clusters have been characterized by X-ray analyses. The structure of the PtII3 cluster core is an approximate or regular isosceles triangle, two equidistant edges (2.51—2.56 Å) being somewhat shorter than the other (2.59—2.61 Å). The cluster core transformation proceeds through the substitution of the in-plane acetate ligands in 1 by incoming ligands followed by the removal of one Pt atom from the tetranuclear cluster core. An intermediate of the cluster core transformation, [{Pt4(CH3COO)4(dmgH)2(dmgH2)}2(μ-dmgH2)], was structurally characterized. It is a dimer of tetranuclear Pt(II) complex and consists of a triangular cluster unit and a mononuclear unit with square planar geometry. EHMO study and large 1JPt-Pt values of ca. 8000 Hz suggest the stability of the triangular PtII3 cluster core and the existence of strong Pt-Pt bonds. Ligands in the PtII3 cluster plane are labilized by trans effect of Pt-Pt bonds, although intramolecular hydrogen bonds reduce the lability. On the other hand, out-of-plane acetate ligands are substitution inert.