Cyclopentadienyl-ruthenium and -osmium chemistry. XXVIII. Reactions and isomerisation of 1,2-bis(methoxycarbonyl)ethenyl complexes: X-ray structure of Ru-(CO)(PPh3)(η-C5H5)*0.5EtOH, and Ru-(PPh3)(η-C5H5)

Article abstract of DOI:10.1016/0022-328X(80)83008-7

A reinvestigation of the reaction between C2(CO2Me)2 and RuH(PPh3)(η-C5H5) and some related complexes is reported.Initial cis addition is followed by conversion into the trans isomer.In the case of the bis-(PPh3) complex, isomerisation is followed by chelation of the ester CO group with concomitant displacement of one PPh3 ligand.The resulting chelate complex reacts with CO or CNBu^t to give thr (Z)-RuC(CO2Me)=CH(CO2Me) complexes; the (E)-isomer of the carbonyl complex is obtained by addition of C2(CO2Me)2 to RuH(CO)(PPh3)(η-C5H5).The (1)H and (13)C NMR spectra are not a reliable guide to assignment of the stereochemistry of the vinyl group.Other products isolated from the initial reaction are tha bis-insertion product and the 1/2 PPh3C2(CO2Me)2 adduct.The molecular structures of Ru<(Z)-C(CO2Me)=CH(CO2Me)>(CO)(PPh3)*0.5EtOH, Ru<(E)-C(CO2Me)=CH(CO2Me)>(dppe)(η-C5H5) and have been determined.The cis isomer is monoclinic, space group P2₁, with a 9.328(8), b 17.385(10), c 10.356(7) Angstroem, β 101.78(3) deg and Z=2; 2107 data with I>/=2.5?(I) were refined to R=0.076, R_w=0.085.The trans isomer is triclinic, space group P1^- with a 10.404(7), b 11.221(6), c 13.230(9) Angstroem, α 92.67(5), β 110.56(5), γ 106.21(5) deg and Z=2; 2520 data with I>/=2.5?(I) were refined to R=0.055, R_w=0.068.The butadienyl complex is monoclinic, space group P2₁/a, with a 19.655(8), b 8.674(4), c 21.060(5) Angstroem, β 116.22(3) deg and Z=4; 2724 data with I>/=2.5?(I) were refined to R=0.043, R_w=0.047.