TY - JOUR
T1 - Iridaoxacyclohexadiene-bridged mixed-valence iridium cyclooctadiene complex
T2 - Oxidative addition and hydrogen-transfer to coordinated cyclooctadiene
AU - Padilla-Martínez, Itzia Irene
AU - Cervantes-Vásquez, Marisol
AU - Leyva-Ramirez, Marco Antonio
AU - Paz-Sandoval, M. Angeles
N1 - Publisher Copyright:
© 2014 American Chemical Society.
PY - 2014/11/24
Y1 - 2014/11/24
N2 - The systematic exploration of the synthesis of heteropentadienyl metal complexes leads us to study the metathesis reaction of [(η4-COD)Ir(μ2-Cl)]2 with lithium 2,4-dimethyloxopentadienide, which affords the dinuclear Ir0-IrII compound (η4-COD)Ir[η1:1-μ2-η4-CHC(Me)CHC(Me)O)]Ir(η4-COD) (1) with a metal-metal bond. The COD ligands are coordinated η4 to each Ir center, whereas the oxopentadienyl ligand is bridging both Ir atoms, allowing the formation of a novel iridapyran complex with IrII and bonding η4 with Ir0. The addition of CO, PMe3, and PMe2Ph to the coordinatively unsaturated complex 1 has led, under mild conditions, to the corresponding dinuclear coordinatively saturated compounds (η4-COD)Ir[η1:1-μ2-η3-CHC(Me)CHC(Me)O)]Ir(η4-COD)(μ2-CO) (2) and (η4-COD)Ir[η1:1-μ2-η4-CHC(Me)CHC(Me)O)]Ir(η4-COD)(PR3) (R = Me, 3; PR3 = PMe2Ph, 4). Compound 3 showed a reversible reaction by dissociation of PMe3, recovering compound 1. The reaction of 1 with H2 and PMe3, PMe2Ph, and P(n-Bu)3 allows the isolation of cyclooctenyl derivatives (η4-COD)Ir[η1:1-μ2-η3-CHC(Me)CHC(Me)O)]Ir(μ2-H)( η1:η2-C8H13)(PR3) (R = Me, 5; R3 = Me2Ph, 6; R = n-Bu, 7), where the hydrogen promotes the formation of a metal-hydride, as well as hydrogen-transfer to one of the coordinated cyclooctadiene ligands. In the presence of molecular hydrogen, 4 leads also to the formation of 6 in better yield. The iridaoxacycle bridging ligand stabilizes these dinuclear iridium complexes, which easily undergo intermolecular insertion into activated C-H bonds. When the more sterically demanding phosphine P(i-Pr)3 is added in the presence of H2, a different reaction takes place, with the displacement of one COD ligand and the formation of (η4-COD)Ir(μ2-H)[ η1:1-μ2-η3-CHC(Me)CHC(Me)O)]Ir(H)(Pi-Pr3)2 (8). The novel complexes 1-8 have been fully characterized, where 1 shows dynamic behavior in one of the COD ligands in solution and gives evidence of two different isomers present in the crystalline structure. Molecular structures of 1-3 and 5-8 have been determined by single-crystal X-ray diffraction studies.
AB - The systematic exploration of the synthesis of heteropentadienyl metal complexes leads us to study the metathesis reaction of [(η4-COD)Ir(μ2-Cl)]2 with lithium 2,4-dimethyloxopentadienide, which affords the dinuclear Ir0-IrII compound (η4-COD)Ir[η1:1-μ2-η4-CHC(Me)CHC(Me)O)]Ir(η4-COD) (1) with a metal-metal bond. The COD ligands are coordinated η4 to each Ir center, whereas the oxopentadienyl ligand is bridging both Ir atoms, allowing the formation of a novel iridapyran complex with IrII and bonding η4 with Ir0. The addition of CO, PMe3, and PMe2Ph to the coordinatively unsaturated complex 1 has led, under mild conditions, to the corresponding dinuclear coordinatively saturated compounds (η4-COD)Ir[η1:1-μ2-η3-CHC(Me)CHC(Me)O)]Ir(η4-COD)(μ2-CO) (2) and (η4-COD)Ir[η1:1-μ2-η4-CHC(Me)CHC(Me)O)]Ir(η4-COD)(PR3) (R = Me, 3; PR3 = PMe2Ph, 4). Compound 3 showed a reversible reaction by dissociation of PMe3, recovering compound 1. The reaction of 1 with H2 and PMe3, PMe2Ph, and P(n-Bu)3 allows the isolation of cyclooctenyl derivatives (η4-COD)Ir[η1:1-μ2-η3-CHC(Me)CHC(Me)O)]Ir(μ2-H)( η1:η2-C8H13)(PR3) (R = Me, 5; R3 = Me2Ph, 6; R = n-Bu, 7), where the hydrogen promotes the formation of a metal-hydride, as well as hydrogen-transfer to one of the coordinated cyclooctadiene ligands. In the presence of molecular hydrogen, 4 leads also to the formation of 6 in better yield. The iridaoxacycle bridging ligand stabilizes these dinuclear iridium complexes, which easily undergo intermolecular insertion into activated C-H bonds. When the more sterically demanding phosphine P(i-Pr)3 is added in the presence of H2, a different reaction takes place, with the displacement of one COD ligand and the formation of (η4-COD)Ir(μ2-H)[ η1:1-μ2-η3-CHC(Me)CHC(Me)O)]Ir(H)(Pi-Pr3)2 (8). The novel complexes 1-8 have been fully characterized, where 1 shows dynamic behavior in one of the COD ligands in solution and gives evidence of two different isomers present in the crystalline structure. Molecular structures of 1-3 and 5-8 have been determined by single-crystal X-ray diffraction studies.
UR - http://www.scopus.com/inward/record.url?scp=84913580596&partnerID=8YFLogxK
U2 - 10.1021/om500392d
DO - 10.1021/om500392d
M3 - Artículo
SN - 0276-7333
VL - 33
SP - 6305
EP - 6318
JO - Organometallics
JF - Organometallics
IS - 22
ER -