Triosmium and triruthenium clusters containing diazaheterocycles

Article abstract of DOI:10.1016/0022-328X(94)05223-X

The reactions of Os3(CO)11(MeCN) with 1-vinylimidazole, imidazole and pyrazole (L-H) result in the formation of Os3(CO)11(L-H) (1, L-H = 1-vinylimidazole; 2, L-H = imidazole; 3, L-H = pyrazole) in good yields.Thermolysis of these complexes at 98 deg C gives two separable isomers of (μ-H)Os3(CO)10(μ-L).In the case of 1 and 2, these isomers are formed by the activation of the two C-H bonds adjacent to the imino nitrogen atom whereas for 3 they are formed by either a C-H or a N-H activation.These isomers interconvert at 128 deg C.The reaction of Ru3(CO)12 with 1-vinyl-imidazole and imidazole in the presence of sodium benzophenone ketyl at 67 deg C yields the cyclodimetallated compounds (7, R=CH=CH2; 8, R=H) in the same isomeric form as the minor isomers in the osmium series.All the new compounds are characterized by IR, 1H-NMR and elemental analysis together with the X-ray crystal structures of 2 and 7.Compound 2 crystallizes in the monoclinic space group P2₁/c with unit cell parameters a = 12.081(2) Angstroem, b = 10.539(2) Angstroem, c = 15.834(2) Angstroem, β = 102.61(2) deg, V = 1959(1) Angstroem³ and Z = 4.Least-squares refinement of 3570 reflections gave a final agreement factor of R = 0.0655 (R_w = 0.0728).Compound 7 crystallizes in the monoclinic space group P2₁/c with unit cell parameters a = 14.665(4) Angstroem, b = 7.5311(9) Angstroem, c = 18.291(4) Angstroem, β = 96.14(1) deg, V = 2008.5(7) Angstroem³ and Z = 4.Least-squares refinement of 3042 reflections gave a final agreement factor of R = 0.0407 (R_w=0.0749). Keywords: Osmium; Heterocycles; Cluster; Diazine; Nitrogen; Hydride