A unique cobalt-gold coordination system, in which the oxidation states of the cobalt centers are closely correlated with the multinuclear molecular structures, is reported. This system contains a Co II 3 Au I 6 nonanuclear structure in [Co 3 {Au 3 (tdme)(D-pen-N,O,S) 3 } 2 ] ([2]) and a Co III Au I 3 tetranuclear structure in [Co{Au 3 (tdme)(D-pen-N,S) 3 }] ([3]) [tdme = 1,1,1-tris(diphenylphosphinomethyl)ethane, D-pen = D-[a]

The 1:1 reaction of [Au2(dppe)(d-Hpen)2] (dppe: 1,2-bis(diphenylphosphino)ethane, d-H2pen: d-penicillamine) with Ni(CH3COO)2·4H2O in ethanol, followed by the vapor diffusion of diethyl ether, gave blue-green crystals of [Au4Ni2(dppe)2(d-pen)4]. This compound showed single-crystal-to-single-crystal conversion on soaking in water, accompanied by the drastic change in complex-molecular arrangements from straight chain to helix structures.

The isolation of 12 secondary metabolites, including seven new acetophenone monomers, from the 50% CH 3 OH/CH 2 Cl 2 extract (N089419-L/6) of Acronychia trifoliolata was reported previously. In the present work, three new prenylated acetophenone dimers (1-3) and five known dimers (4-8) were isolated, and their structures were elucidated by using various NMR spectroscopic techniques and HRMS. Among the new dimers, an unprecedented 4-isobutyl-3 isopropyltetrahydro-2H-pyran ring was observed in the structure of 1. This study is the first to report the formation of a 2H-pyran ring between two prenylated acetophloroglucinols. Only four related dimers have been reported before, and they were formylated phloroglucinol dimers from the family Eucalypteae. Compounds 2 and 3 are acrovestone-like dimers, and the structure of 3 was confirmed by total synthesis. The evaluation of the antiproliferative activity of isolated and synthesized acrovestone-like dimers indicated that a double bond in the prenyl-like moiety as *