Cyclopentadienyl-ruthenium and -osmium chemistry. XXV. Conversion of alkoxycarbene complexes to vinyl ether derivatives

Abstract

Several cationic alkoxy(alkyl)carbene complexes containing the Ru(L)(PPh3)(η-C5H5) (L = CO or PPh3) moiety have been deprotonated with NaOMe to the corresponding vinyl ether derivatives. The reaction is reversed by addition of HPF6. Many of the vinyl ether complexes were obtained as mixtures of E and Z isomers; the X-ray structure of Ru{;C(OPr1)CHPh}(CO)(PPh3)(η-C5H5) shows that it is obtained only as the E isomer, and that the unit cell contains equal numbers of the two enantiomers. Ru{;C(OPr1)CHPh};(CO)(PPh3)(η-C5H5) is monoclinic, space group P21/c, with a 10.337(5), b 15.161(4), c 18.714(5) Å, β 90.83(3)°, and Z = 4; 2240 reflections [I > 2.5σ(I)] were refined to R = 0.0388, Rw = 0.0436. Important distances: RuC(vinyl) 2.103(6), RuCO 1.832(7), RuP 2.298(2), CC(vinyl) 1.335(8), COMe 1.381(7) Å. Addition of NaOMe to the product of the reaction between RuCl(PPh3)2(η-C5H5) and HCCC(O)Me in MeOH afforded a mixture of Ru{;CCC(O)Me};(PPh3)(η-C5H5) and Ru{;C(OMe)CHC(O)Me};(PPh3)2(η-C5H5). The latter loses PPh3 on standing in solution at ambient temperatures, forming the chelate complex Ru{;C(OMe)CHC(O)Me};(PPh3)(η-C5H5). The similar conversion of Ru{;C(OMe)CHC(O)OMe};(PPh3)2(η-C5H5) to the corresponding chelate complex required heating at 65°C for 75 minutes. Show more