The tetranuclear ruthenium clusters [Ru₄(CO)₆(µ-CO)₃(µ₄-S)₂{C(NHR)₂}₂]1(R = Prⁱ) and 3(R = Et) and [Ru₄(CO)₇(µ-CO)₃(µ₄-S)₂{C(NHR)₂}]2(R = Prⁱ) and 4(R = Et) were obtained from the thermal reaction of [Ru₃(CO)₁₂] with thioureas SC(NHR)₂(R = Prⁱ or Et). In the case of diethylthiourea, a trinuclear cluster [Ru₃(µ-H)(CO)₉(µ₃-NEtCSNHEt)]5 was isolated in addition to 3 and 4. The single-crystal X-ray structure analyses of 1 and 2 reveal a pseudo-octahedral Ru₄S₂ skeleton with three µ-carbonyl bridges in the Ru₄ plane; 1 has two terminal diaminocarbene ligands and six terminal carbonyls, whereas there is only one terminal diaminocarbene ligand but seven terminal carbonyls in 2.

The synthesis and mesomorphic behaviour of the first family of 1,1′-disubstituted ruthenocene-containing liquid crystals are reported.