Tetra- and hexanuclear cage molecules based on diruthenium tetracarbonyl sawhorse units: Synthesis and molecular structure of [{Ru2(CO)4(PPh3)2}2(O2CCH2CO2)2] and [{Ru2(CO)4(PMe3)2}3(O2CC6H4CO2)3]

The thermal reaction of Ru3(CO)12 with malonic acid, followed by the addition of the corresponding ligand, yields to the tetranuclear ruthenium complexes [{Ru2(CO)4L2}2(O2CCH2CO2)2] (L = PPh3: 1, L = 3,5-(CH3)2-NC5H3: 2), while the reaction of Ru3(CO)12 with terephthalic acid, followed by the addition of the corresponding ligand, gives rise to the formation of the hexanuclear ruthenium complexes [{Ru2(CO)4L2}3(O2CC6H4CO2)3] (L = PMe3: 3, L = 3,5-(CH3)2-NC5H3: 4). The single-crystal X-ray structure analyses for 1 and 3, reveal both cages to consist of Ru2(CO)4 sawhorse units, 1 being a molecular loop, while 3 is a molecular triangle.