title: Molybdenum 17- and 18-electron bis- and tris(butadiene) complexes: electronic structures, spectroscopic properties, and oxidative ligand substitution reactions.
abstract: New results on the electronic structures, spectroscopic properties, and reactivities of the molybdenum tris(butadiene) and tris(2,3-dimethylbutadiene) complexes [Mo(bd)3] (1(bd)) and [Mo(dmbd)3] (1(dmbd)), respectively, are reported. Importantly, the metal ligand bonding interaction can be weakened by oxidizing the metal center with ferrocenium salts. The addition of the bidentate phosphine ligand 1,2-bis(diphenylphosphino)ethane then leads to a new type of stable 17-electron complex, [Mo(dmbd)2(dppe)](X) (2; X = BF4(-), PF6(-), BPh4(-)), where one of the butadiene ligands is exchanged by a chelating phosphine. Reduction of the cationic complexes 2 generates the corresponding 18-electron complex [Mo(dmbd)2(dppe)] (3), thus establishing a new strategy for ligand substitution reactions in [Mo(bd)3] complexes via one-electron oxidized intermediates. The new heteroleptic molybdenum complexes are characterized by X-ray structure analysis; vibrational, NMR, and EPR spectroscopy; and electrochemistry. DFT calculations are performed to explain the structural and specroscopic trends observed experimentally. For compound 1(bd), a normal coordinate analysis is presented, providing additional information on the bonding situation in this type of complex.
authors.affiliation: Institut für Anorganische Chemie, Christian Albrechts Universität zu Kiel, Max-Eyth-Straße 2, D-24098 Kiel, Germany.
authors.forename: Gerald C
authors.initials: GC
authors.lastname: Stephan
authors.forename: Christian
authors.initials: C
authors.lastname: Näther
authors.forename: Gerhard
authors.initials: G
authors.lastname: Peters
authors.forename: Felix
authors.initials: F
authors.lastname: Tuczek
mesh_terms: D002070:Butadienes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D002070:Butadienes; D008024:Ligands; D009942:Organometallic Compounds; D008982:Molybdenum