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 Ru 3 (CO) 12 with molten benzoic acid yields Ru 2 (C 6 H 5 COO) 2 (CO) 4 (1) and Ru 2 (C 6 H 5 COO) 2 (CO) 6 (2). Ru 2 (CH 3 COO) 2 (CO) 6 (3) was obtained in small yield by annealing Ru 2 (CH 3 COO) 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 2 1 /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 Ru 2 (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 σ 2 π 4 δ 2 δ ∗2 . Polymer 1 reacts reversibly with CO at 1 bar pressure to form 2.