Cyclopentadienyl-ruthenium and -osmium complexes: V. Synthesis, reactivity and crystal structure determination of carbonylchloro(η-cyclopentadienyl)-(triphenylphosphine)ruthenium(II)☆

CpRuCl(CO)PPh3 is formed as the result of refluxing CpRuCl(PPh3)2 in ethylene glycol (yield up to 15%). A dissociation process is postulated with liberation of one PPh3 molecule and simultaneous rearrangement of the cation formed earlier: [CpRu(CO)(PPh3)2]+ Cl− → CpRuCl(CO)PPh3 + PPh3. CpRuCl(CO)PPh3 reacts reluctantly with the alkoxy anion to give CpRuH(CO)PPh3, in contrast to CpRuCl(PPh3)2, which undergoes very facile transformation into CpRuH(PPh3)2. The structure of CpRuCl(CO)PPh3 has been determined by the single-crystal X-ray diffraction method. The compound is triclinic, space group P1, a 9.378(2), b 10.584(2), c 16.590(4) A, α 126.11(1), β 55.91(1), γ 101.49(1)°. The unit cell contains both R and S enantiomers. A shorter distance of the RuCl bond has been noted in CpRuCl(CO)PPh3 (2.396 A) in comparison with the RuCl distance in CpRuCl(PPh3)2 (2.453 A). This causes a diminishing tendency to lose a chloride ion and as a result, nucleophilic attack of RO− on CpRuCl(CO)PPh3.