Half-sandwich ruthenium complexes of a P–O bifunctional ligand. X-Ray crystal structure of [Ru(η-C5Me5)(OC6H4PPh2){PPh2(C6H4OH)}]

Abstract

The reaction of the phosphine PPh₂(C₆H₄OH) with a reduced solution of [{Ru(η-C₅Me₅)Cl₂}_n](1) by zinc in methanol produces [Ru(η-C₅Me₅)(OC₆H₄PPh₂){PPh₂(C₆H₄OH)}](4). This complex crystallizes in the monoclinic system, space group P2₁/c, with a= 11.070(1), b= 18.582(2), c= 19.393(2)Å, and β= 106.05(1)° and was refined to R= 0.028 with 4 383 reflections having (F_o²) > 3σ(F_o²). The X-ray structure shows the compound to exhibit strong hydrogen bonding between the hydroxyl proton of the phosphine and the oxygen group of the chelating phenoxy diphenylphosphine ligand [O ⋯ O 2.534(3), O–H 0.97(3), and H ⋯ O 1.57(3)Å]. Compound (4) is unreactive towards H₂, NaBH₄, LiBHEt₃, CF₃CO₂H, and MeI probably because of electronic and co-ordinative saturation. Reaction of the hydroxyphosphine with [{Ru(η-C₅Me₅)Cl}₄] followed by addition of NEt₃ leads to an insoluble solid (5) of the same composition as (4) but proposed to be oligomeric. Compound (5) is again unreactive except with HBF₄·Et₂O in the presence of which it decomposes. Reaction of PPh₂(C₆H₄OSiMe₃) with a reduced solution of (1) in methanol affords [Ru(η-C₅Me₅)(OC₆H₄PPh₂){PPh₂(C₆H₄OSiMe₃)}](6) whereas addition of PPh₂(C₆H₄OH) to (1) followed by reduction with NaBH₄ in ethanol affords the trihydride [Ru(η-C₅Me₅)H₃{PPh₂(C₆H₄OH)}](8).