Cyclopentadienyl-ruthenium and -osmium chemistry: XXVIII. Reactions and isomerisation of 1,2-bis(methoxycarbonyl)ethenyl complexes: X-ray structures of Ru{ Z)-C(CO 2Me)CH(CO 2Me)} -(CO)(PPh 3)(η-C 5H 5) · 0.5EtOH, Ru{( E)-C(CO 2Me)CH(CO 2Me)}(dppe)(η-C 5H 5) and [formula omitted]CH(CO 2Me)} - (PPh 3)(η-C 5H 5)

Abstract

A reinvestigation of the reaction between C 2(CO 2Me) 2 and RuH(PPh 3) 2(η-C 5H 5) and some related complexes is reported. Initial cis addition is followed by conversion into the trans isomer. In the case of the bis-(PPh 3) complex, isomerisation is followed by chelation of the ester CO group with concomitant displacement of one PPh 3ligand. The resulting chelate complex reacts with CO or CNBu t to give the ( Z)-RuC(CO 2Me)CH(CO 2Me) complexes; the ( E)-isomer of the carbonyl complex is obtained by addition of C 2(CO 2Me) 2to RuH(CO)(PPh 3)(η-C 5H 5). The 1Hand 13C NMR spectra are not a reliable guide to assignment of the stereochemistry of the vinyl group. Other products isolated from the initial reaction are the bis-insertion product Ru{C(CO 2Me)C(CO 2Me)C(CO 2Me) CH(CO 2Me)} -(PPh 3)(η-C 5H 5) and the 1/2 PPh 3/C 2(CO 2Me) 2 adduct. The molecular structures of Ru{( Z)-C(CO 2Me)CH(CO 2Me)}(CO)(PPh 3(η-C 5H 5) · 0.5EtOH, Ru{( E)-C(C 2Me)CH(CO 2Me)}(dppe)(η-C 5H 5) and Ru{C(CO 2Me)C(CO 2Me)C(CO 2-Me) CH(CO 2Me)}(PPh 3)(η-C 5H 5) have been determined. The cis isomer is monoclinic, space group P2 1,with a 9.328(8), b 17.385(10), c 10.356(7) Å, β 101.78(3)° and Z = 2; 2107 data with I ≥ 2.5σ( I) were refined to R = 0.076 R w = 0.085. The trans isomer is triclinic, space group P 1 , with a 10.404(7) b 11.221(6), c 13.230(9) Å, α 92.67(5), β 110.56(5), γ 106.21(5)° and Z = 2; 2520 data with I ≥ 2.5σ( I) were refined to R = 0.055 R w = 0.068. The butadienyl complex is monoclinic, space group P2 1/ a, with a 19.655(8), b 8.674(4), c 21.060(5) Å, β 116.22(3)° and Z = 4; 2724 data with I ≥ 2.5σ( I) were refined to R = 0.042, R w = 0.047.