The following platinum‐group chelate complexes with 5‐R‐9‐hydroxyphenalenone (L1: R = H; L2: R = Me; L3: R = Pr) have been prepared: [RhI(L)(CO)2] (1a: L = L1; 1b: L = L2; 1c: L = L3), [PdII(L)2] (2a: L = L2; 2b: L = L3), [PtII(L1)(NH3)2](NO3) (3), and (Bu4N)[PtII(L1)(Cl)2] (4). Compounds 1a and 1b are different colors in the solid state: yellow and deep red, respectively. X‐ray analysis revealed that 1a has a regular π–π stacking structure while 1b has a dimer‐like arrangement with a RhI–RhI distance of 3.2336(6) Å. Both solids were luminescent at 77 K. Compounds 2a and 2b are planar extended π‐conjugated complexes, which exhibit two‐dimensional stacking modes in the crystal. The solid‐state structure of complex 3 is hydrogen‐bonded in a polar arrangement. The cytotoxic activities of 1a, 3, and 4, evaluated in vitro against HL60 human acute myeloid leukemia cell lines, were comparable to that of cisplatin. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The crystal architecture, magnetic properties, and thermodynamic properties of [n-butylferrocene][Ni(mnt)2] (1), [tert-butylferrocene][Ni(mnt)2] (2), [1,1'-diethylferrocene][Ni(mnt)2] (3), and [1,1'-diisopropylferrocene][Ni(mnt)2] (4) were investigated (mnt=maleonitriledithiolate). These complexes exhibit a unique supramolecular structure in which the ferrocenium cations constitute honeycomb-like assembled structures surrounding columns of the anions. For 1, the cations form a dimer through a very short intermolecular ferrocene-ferrocene distance of 3.28 A, which mediates an antiferromagnetic interaction with a singlet-triplet energy gap of 5 K. First-order phase transitions occur in 1-3 at 364, 361, and 350 K, respectively, accompanied by thermal hysteresis.