Benzoatokomplexe des Rutheniums, 1. Mitt. Synthese, Eigenschaften und Kristallstruktur von Ru₂(C₆H₅COO)₄(C₆H₅COOH)₂ und Ru₂(C₆H₅COO)₅·C₆H₅COOH / Benzoato Complexes of Ruthenium , Part 1 Synthesis, Properties and Crystal Structure of Ru₂(C₆H₅COO)₄(C₆H₅COOH)₂ and Ru₂(C₆H₅COO)₅·C₆H₅COOH

Abstract

Ru 2 (C 6 H 5 COO) 4 (C 6 H 5 COOH) 2 (1) is formed as main product besides small amounts of Ru 2 (C 6 H 5 COO) 5 ·C 6 H 5 COOH (2) by the reaction of Ruthenium (III) acetylacetonate in molten benzoic acid. 1 forms monoclinic black crystals with the space group P2 1 /n and the lattice constants a = 1091.0, b = 1164.1, c = 1526.8 pm, β = 90.53°, Z = 2.2 is obtained as triclinic red needles with the space group P1̄ and the lattice constants a - 1178.4, b = 1605.3, c = 1043.9 pm, a = 99.07°, β = 95.45°, y - 83.22°, Z = 2. Both com pounds exhibit carboxylate bridged dimers [Ru 2 (C 6 H 5 COO) 4 ] n+ (n=0, 1). In case of the isolated Ru(II) dimer 1 two benzoic acid m olecules occupy axial positions and form hydrogen bridges to carboxylate O-atoms. 1 is paramagnetic with two unpaired electrons per dimeric unit corresponding to an electron configuration σ 2 π 4 δ 2 π* 3 δ* and a bond order of 2 (Ru-Ru = 226.3 pm ). It decomposes at 230 °C to Ru 2 (C 6 H 5 COO) 4 and at 350 °C to Ru metal. 2 is polymeric. A benzoate anion functions as bridging ligand between [Ru 2 (C 6 H 5 COO) 4 ] + dimers. The benzoic acid molecule is weakly associated to the polymer by an H-bridge. A Ru-Ru bond order of 2.5 and a Ru-Ru distance of 227.7 pm are observed.