title: Overcoming Statistical Complexity: Selective Coordination of Three Different Metal Ions to a Ligand with Three Different Coordination Sites.
abstract: In general, it is difficult to selectively introduce different metal ions at specific positions of a cluster-like structure. This is mainly due to statistical problems as well as the reversibility of the formation of coordination bonds. To overcome this statistical problem, we used a carefully designed ligand, H6 L, which can accommodate three different kinds of metal ions in three types of coordination sites. The complex [LNiZn2La](3+), which contains three different metals, was quantitatively obtained by a stepwise procedure, but different products were obtained when the metal ions were added in a different order. However, equilibration studies indicated that this complex was almost solely formed among 54 (=3×3×3H2) possible products upon heating; the formation efficiency (ca. 100%) was significantly higher than the statistical probability (2.47%). Such carefully designed ligands should be useful for the synthesis multimetallic systems, which are of interest because of the interplay between the different metals.
authors.affiliation: Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan. akine@se.kanazawa-u.ac.jp.
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Akine
authors.affiliation: Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8571, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8571, Japan. nabesima@chem.tsukuba.ac.jp.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Nabeshima
keywords: cluster compounds; heterometallic complexes; ligand design; programmed synthesis; site-selective synthesis