Synthesis and reaction of ruthenium(II) complexes containing heteroatom donor (O, N, and P) tethered to η6-arene ring

Synthesis of ruthenium(II) complexes chelated by the η6-arene ring and a pendent donor atom (O, N, and P) is described. The alcohol-containing η6-arene ruthenium complexes [Ru{η6-C6H5(CH2)3OH}(PR3)Cl2] (1a R=Ph; 1b R=Et) and [Ru{η6-C6H5(CH2)3OH}L2Cl]BF4 (2a L2=2,2′-bipyridine; 2b L2=1,10-phenanthroline; 2c L2=2,2-bis[4(R)-phenyl-1,3-oxazolon-2-yl]propane, (R)-bpop) were prepared by treatment of [Ru{η6-C6H5(CH2)3OH}Cl2]2 with tertiary phosphines or N,N′-chelate ligands/NaBF4, respectively. Addition of 1 equiv. of AgBF4 to a solution of complexes 1 or 2 gave alcohol chelate complexes [Ru{η6:η1-C6H5(CH2)3OH}(PR3)Cl]BF4 (3a–b) or [Ru{η6:η1-C6H5(CH2)3OH}L2](BF4)2 (4a–c), respectively. Although stable in MeOH, the alcoholRu chelate bond of 3 and 4 was cleaved by Cl− ion. Treatment of 4 with bases (OH−, R3N) led to abstraction of the hydroxy proton to give alkoxy chelate complexes [Ru{η6:η1-C6H5(CH2)3O}L2]BF4 (5a–c). In CH2Cl2 acidity of the hydroxy proton in 4c was revealed to be comparable to that of N-methylbenzylammonium cation (pKa in H2O, ca. 11). Amino chelate complexes [Ru{η6:η1-C6H5(CH2)nNH2}(PPh3)Cl]BF4 (7an=3; 7bn=2) were prepared by treatment of ammonium complexes [Ru{η6-C6H5(CH2)nNH3Cl}(PPh3)Cl2] (6an=3; 6bn=2) with 1 equiv. of NaOH and NaBF4. 7 were stable to the attack of Cl− ion. In contrast, the similar treatment of dimethylammonium derivative [Ru{η6-C6H5(CH2)3NMe2HCl}(PPh3)Cl2] (8) with KOH gave a non-chelate complex [Ru{η6-C6H5(CH2)3NMe2}(PPh3)Cl2] (9). Phosphorous chelate complexes [Ru{η6:η1-C6H5(CH2)3OPPR2}Cl2] (10a R=Ph; 10b R=iPr) were prepared by reaction of [Ru{η6-C6H5(CH2)3OH}Cl2]2, PPR2Cl, and EtNiPr2. Treatment of 10b with AgBF4 and CO (1 atm) gave the cationic carbonyl complex [Ru{η6:η1-C6H5(CH2)3OPiPr2}(CO)Cl]BF4 (11).