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The thermal reaction of the dinuclear complex [Ru2(CO)4(O2CH)2(PCy2H)2] with molecular hydrogen in cyclohexane afforded the tetranuclear clusters [H4Ru4(CO)8(PCy2)4] (64e) and [H5Ru4(CO)8(PCy2)3] (62e), both of which have a square-planar arrangement of the metal framework.

The co-ordination of the six-membered crown thioethers 1,3,5-trithiane, 2-methyl-, 2,4-dimethyl-, 2,4,6-trimethyl-, 2-benzyl- and 2,4,6-tribenzyl-1,3,5-trithiane and the nine-membered crown thioether 1,4,7-trithiacyclononane to the cobalt skeleton of various Co3C clusters was studied. With trithiane and its derivatives complexes of the type [Co3(CO)6(µ3-SCHR1SCHR2SCHR3)](R = Cl, Me or Ph; R1– R3= H, Me or CH2Ph) were obtained, whereas the nine-membered crown thioether gave compounds of the type [Co3(CO)5(µ-CO)(µ3-CR){(SCH2CH2)3}]. The molecular and crystal structures of several representatives have been investigated by single-crystal X-ray diffraction. It has been shown that the trithiane ligand invariably occupies the axial co-ordination sites on the three cobalt atoms, while the trithiacyclononane chelates on one cobalt atom. The intermolecular networks of hydrogen-bonding interactions of the C–H ⋯ O type between the thioether hydrogens and the CO ligands have been investigated and compared with those present in other crystalline clusters carrying thioether ligands.

The low-pressure hydrogenation of the hydrolysis mixture of [Ru2(η6-C6H6)2Cl4] in water (1.5 atm, 20 °C) led, in the presence of NaClO4, to the oxo-capped trinuclear cluster cation [Ru3(η6-C6H6)3(µ-Cl)(µ3-O)(µ-H)2]+1 which crystallized as the perchlorate salt. The chloro-capped trinuclear cluster cation [Ru3(η6-C6H2Me-1,2,4,6)3(µ3-Cl)H3]2+2, crystallized as the dichloride, was accessible from the durene derivative [Ru2(η6-C6H2Me-1,2,4,6)2Cl4] by high-pressure hydrogenation (60 atm, 55 °C) in water. In hot aqueous solution, the chloro-capped cluster 2 underwent hydrolysis to give the oxo-capped cluster [Ru3(η6-C6H2Me4-1,2,4,6)3(µ3-O)H3]+3. In the presence of NaBF4, the low-pressure hydrogenation (1.5 atm, 20 °C) of the hydrolysis mixture of [Ru2(η6-C6H6)2Cl4] led to the tetranuclear tetrahydrido cluster cation [Ru4(η6-C6H6)4H4]2+4 which precipitated as the tetrafluoroborate salt. Under high-pressure conditions (60 atm, 55 °C) and in the absence of an additional salt, the hexahydrido cluster cation [Ru4(η6-C6H6)4H6]2+5 was formed and obtained as the dichloride. By analogy, the p-cymene derivative [Ru2(η6-C6H4MePri-p)2Cl4] gave [Ru4(η6-C6H4MePri-p)4H6]2+6. In contact with air, the hexahydrido clusters 5 and 6 were transformed into the corresponding tetrahydrido clusters [Ru4(η6-C6H6)4H4]2+4 and [Ru4(η6-C6H4MePri-p)4H4]2+7. The hexahydrido cluster 5 is capable of hydrogenating fumarie acid to give succinic acid and 4; the latter adds molecular hydrogen to regenerate the hexahydrido species 5. The crystal and molecular structures of the cluster salts [Ru3(η6-C6H6)3(µ-Cl)(µ3-O)(µ-H)2]ClO4(cation 1), [Ru3(η6-C6H2Me4-1,2,4,6)3(µ3-O)H3]BF4(cation 3), [Ru4(η6-C6H6)4H4]Cl2(cation 4) and [Ru4(η6-C6H4MePri-p)4H6][ClO4]2(cation 6) have also been determined.

Based on the principle of supramolecular preorganization, a new type of oligofunctional amphiphile, of which compounds 1-4 are representative structures, has been designed and synthesized. The typical feature of their structure is a highly rigid and geometrically well-defined central unit composed of ethynylene substituted aromatic spacers with different numbers of amphiphilic segment groups (also of a rigid geometric design) attached to it. The molecules form well-defined Langmuir films when spread from a solution at the air/water interface or when a 10(-4) M aqueous CaCl2 solution was used as the subphase. By analysis of the surface pressure-surface area (pi-A) isotherms, information on the packing behavior and orientation of the amphiphilic molecules depending on the molecular structure could be obtained. Morphological characterization of the dynamic process of monolayer compression at the air/water interface was carried out by Brewster angle microscopy, illustrating several phase states visualized as snap shots. Thin monolayer films produced on a 10(-4) M aqueous CaCl2 subphase can be transferred to a mica solid support by the Langmuir-Blodgett technique. Tapping mode atomic force microscopy reveals a surface topography of the monofilms composed of 1 and 3 that differ in roughness and also in the properties of elasticity, hardness and adhesive strength. X-Ray crystal structure analysis of three relevant intermediate compounds of the synthesis were successfully determined giving an indication of the potential structural features inherent in the new amphiphiles.