Ruthenium Complexes of Stibino Derivatives of Carboxylic Amides: Synthesis and Characterization of Bidentate Sb,E, Tridentate Sb,E2, and Tetradentate Sb,E3 (E = N and O) Ligands and Their Reactivity Toward [RuCl2(PPh3)3].

Neutral bi-, tri-, and tetradentate ligands of the type Ph3-xSb(L)x [x = 1 (1), 2 (2), and 3 (3). L = La = phthalimidinyl (1a, 2a, and 3a), Lb = 2-pyridyloxy (1b, 2b, and 3b)] have been synthesized and characterized. Reaction of the Sb,E and Sb,E2 ligands with [RuCl2(PPh3)3] proceeded under anion scrambling with formation of complexes of type [Ph2Sb(μ-L)2Ru(PPh3)(μ-Cl)]2 (5) or [PhSb(μ-L)3RuCl(PPh3)] (8) in addition to various byproducts. Reactions of the Sb,E3 ligands and [RuCl2(PPh3)3] afforded highly diverse product mixtures. Deliberate syntheses of complexes of types 5 and 8 were successful by supplementing the reaction mixture with the required stoichiometric amount of either HLa or HLb and a supporting base. The Sb-Ru bonds, which are bridged by two (type 5) or three (type 8) phthalimidinyl or 2-pyridyloxy ligands, have been investigated using quantum chemical calculations at the DFT level (NBO/NLMO and AIM). Treatment of complexes of type 8 with fluoride ions resulted in the formation of compounds of type [PhFSb(μ-La)3RuL'(PPh3)] (L' = O2 (9a-O2), NCMe (9a-NCMe), or [PhFSb(μ-Lb)2Ru(κ2-Lb)(PPh3)] (10b)). In contrast to other similar bimetallic Sb-TM complexes (TM = transition metal), which may switch the rather dative intermetallic bond from Sb→TM to Sb←TM upon replacing TM bound chloride by Sb-bound fluoride, the character of the Sb→Ru bond is essentially retained upon going from chloro complex 5 or 8 to fluoro complex 9 or 10. Charge discrepancies caused by anion transfer from Ru to Sb are mainly compensated for by charge flow along the ligand backbone. All isolated complexes were characterized with multinuclear NMR spectroscopy, single-crystal X-ray diffraction, elemental analysis, and quantum chemical calculations.