Mono- and Bis-Bridged Ru-Rh Complexes. Preparation, Characterization, and Reactivity. X-ray Crystal Structure of RuRhH(Ph)(PhPCH2PPh2)(Ph2PCH2PPh2)(C8H12)*1/2PhMe and of RuHCl(Ph2PCH2PPh2)2*1/2PhMe

Article abstract of DOI:10.1021/ja00273a026

The reaction of RuCOD(dppm)2 (COD = cis,cis-1,5-cyclooctadiene, dppm = bis(diphenylphosphino)methane) with 2 affords Ru(CO)(COD)(dppm) and 2 at room temperature after ligand exchange.At 80 deg C two further products are obtained, Rh2Cl2(dppm)2 and RuRhCl(CO)3(dppm)2 (1), which is the main product if the reaction is performed under CO.A mechanism is proposed. 1 reacts with H2 to give RuRhH2Cl(CO)2(dppm)2 which can also be obtained from RuH2(dppm)2 and 2.The reaction of RuH2(dppm)2 with 2 leads to RuRhH2Cl(COD)(dppm)2 (3) which contains one bridging and one chelating dppm group. 3 does not react with C2H4, decomposes under H2, and reacts with CO to give 1 and with P(OMe)3 to give two isomers of RuHClP(OMe)3(dppm)2, 5 and 6, and RhH(POMe3)4.Similarly, the reaction of RuH2(dppm)2 with 2 produces RuIrH2Cl(COD)(dppm)2 (4) analogous to 3, but in this case some redistribution to RuHCl(dppm)2 is also observed.Finally, reduction of 3 with MeLi at 0 deg C leads to methane elimination and the formation of RuRhH(Ph)(PhPCH2PPh2)(dppm)(COD) (7) which contains a phosphido bridge between Ru and Rh and a trans hydrido phenyl environment for ruthenium. 7 reacts with CO to give RuRhH(Ph)(PhPCH2PPh2)(dppm)(CO)2 (8).Full spectroscopic characterization of the new complexes is described, viz., 1H, 13C, and 31P NMR and determination of the 103Rh resonance frequency.The crystal structures of RuHCl(dppm)2*1/2PhMe and of 7 are described.RuHCl(dppm)2*1/2PhMe: C_2h⁵-P2₁/c; Z = 4; a = 10.138(2) Angstroem, b = 21.206(3) Angstroem, c = 22.066(3) Angstroem, β = 103.93(1) deg, V = 4604.4 Angstroem³, R = 0.046 for 2948 reflections with F₀² > 3?(F₀²).RuRhHPh(PhPCH2PPh2) (COD)(dppm)*0.5PhMe: C_2h⁵-P2₁/c; Z = 4; a = 15.985(3) Angstroem, b = 18.324(4) Angstroem, c = 19.496(4) Angstroem, β = 112.20(2) deg, V = 5287.2 Angstroem³, R = 0.034 for 4751 reflections with F₀² > 4?(F₀²).