Synthesis, structures and reactions of doubly bridged biscyclopentadienyl diruthenium complexes (CR2)(EMe2)[(η5-C5H3)Ru(CO)2]2 (R = Me, H; E = Si, Ge)

Doubly bridged biscyclopentadienyl diruthenium complexes (CR2)(EMe2)[(η5-C5H3)Ru(CO)2]2 (R = Me, E = Si (2), Ge (5); R = H, E = Si (7), Ge (10)) were synthesized, and fully characterized by 1H NMR, IR, EA and single crystal X-ray diffraction. Due to the rigid double-bridged biscyclopentadienyl ligands and the long Ru–Ru bonds in their structures, a series of reactions about (CMe2)(SiMe2)[(η5-C5H3)Ru(CO)2]2 (2), as a representative for this type of complexes, were carried out: 2 reacted with halogens to give unexpected halogen-bridged products (CMe2)(SiMe2)[(η5-C5H3)2Ru2(CO)3(X)](μ-X) (X = I (12), or Br (14)), in addition to the normal Ru–Ru-cleaved compounds (CMe2)(SiMe2)[(η5-C5H3)Ru(CO)2X]2 (X = I (11), or Br (13)); UV photolysis of 2 with PPh3 resulted in loss of two carbon monoxide ligands and P–C insertion by ruthenium to yield the complex (CMe2)(SiMe2)[(η5-C5H3)2Ru2(CO)2(σ-Ph)][μ-PPh2] (15); with C2Ph2 yielded [(CMe2)(SiMe2)(η5-C5H3)2]Ru2(CO)[η2:η4-μ2-C(Ph)C(Ph)C(Ph)C(Ph)] (16). Reactivity of doubly bridged ruthenium complex 2 with the respective non-bridged and singly bridged analogues was compared. The molecular structures of 12, 15 and 16 were also determined by X-ray diffraction.