title: Cyclic tetramers composed of rhodium(III), iridium(III), or ruthenium(II) half-sandwich and 6-purinethiones.
abstract: Six new cyclic tetranuclear complexes [[M(Cp*)(L)](4)](4+) and [[Ru(II)(L)(cymene)](4)](4+) [Cp* = eta(5)-C(5)Me(5), cymene = eta(6)-p-MeC(6)H(4)Pr(i); M = Rh(III) and Ir(III); HL = 6-purinethione (H(2)put) and 2-amino-6-purinethione (H(2)aput)] were prepared in a self-assembly manner and characterized by NMR spectroscopy, electrospray ionization mass spectrometry, and X-ray crystal structure analysis. The two crystal structures of [[Rh(Cp*)(H(0.5)put)](4)](CF(3)SO(3))(2) and [[Ir(Cp*)(Haput)](4)](CF(3)SO(3))(4) revealed that they have similar S(4) structures with an alternate chirality array of CACA, and all ligands adopt a mu-1kappaN(9):2kappa(2)S(6),N(7) coordination mode. The orientations of the four bridging ligands are alternately up and down, and they form a central square cavity. Interestingly, the cationic tetramers of the former are stacked up along the c axis, resulting in an infinite channel-like cavity. The driving force of this stacking is due to intermolecular double hydrogen bonds [N(1)-H...N(21) = 2.752(4) A] at both sides of the cavity. In the two Rh(III)- and Ru(II)-H(2)aput systems, it turned out that the dimeric species are dominantly formed in the reaction solutions but finally convert into the tetrameric species.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, 1-16 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan. yamanari@ch.wani.osaka-u.ac.jp
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Yamanari
authors.forename: Rie
authors.initials: R
authors.lastname: Ito
authors.forename: Shiori
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Takumi
authors.initials: T
authors.lastname: Konno
authors.forename: Akira
authors.initials: A
authors.lastname: Fuyuhiro
authors.forename: Kousuke
authors.initials: K
authors.lastname: Fujioka
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Arakawa