Benzoatokomplexe des Rutheniums, 2. Mitt. Synthese, Eigenschaften und Kristallstruktur von Ru2(C6H5COO)2(CO)4, Ru2(C6H5COO)2(CO)6 und Ru2(CH3COO)2(CO)6/Benzoato Complexes of Ruthenium, Part 2 Synthesis, Properties and Crystal Structure of Ru2(C6H5COO)2(CO)4, Ru2(C6H5COO)2(CO)6 and Ru2(CH3COO)2(CO)6

Abstract

Abstract The reaction of Ru3(CO)12 with molten benzoic acid yields Ru2(C6H5COO)2(CO)4 (1) and Ru2(C6H5COO)2(CO)6 (2). Ru2(CH3COO)2(CO)6 (3) was obtained in small yield by annealing Ru2(CH3COO)2(CO)4 over a period of 3 weeks at 145 °C in a sealed glass am poule. 1 forms orthorhombic, orange needles crystallizing in the space group Pbca, with the lattice constants a = 974.9, b = 2090.5, c = 1830.1 pm, Z = 8 . 2 crystallizes as monoclinic, yellow needles in the space group C2/m with a = 1879.2, b = 1168.3, c = 1029.3 pm, β = 103.77°, Z = 4. 3 is obtained in the form of yellow platelets which crystallize in the space group P 21/c and with lattice constants a = 792.3, b = 2802.6, c = 1440.9 pm, β = 100.65°, Z = 8. All three complexes consist of dimeric units Ru2(RCOO)2(CO)4 with bridging carboxylato groups in cis positions. In the case of 1 these units are linked together by additional Ru -O bonds between neighbouring dimers to form polymer chains. 2 and 3 are isolated complexes with the axial positions occupied by CO ligands. The diamagnetism as well as the Ru -Ru distances (1: 263.9 pm; 2: 270.4 pm; 3: 269.0 and 268.8 pm) are in agreement with a Ru-Ru single bond and the electron configuration σ2π4δ2δ∗2. Polymer 1 reacts reversibly with CO at 1 bar pressure to form 2.