TY - JOUR
T1 - Synthesis and Reactivity of (η3-pentadienyl)Ir(PEt3)2and (η3-2,4-dimethylpentadienyl)Ir(PEt3)2
AU - Bleeke, John R.
AU - Luaders, Scott T.
PY - 1995/4
Y1 - 1995/4
N2 - Treatment of [ClIr(PEt3)2]2with potassium pentadienide or potassium 2,4-dimethylpentadienide produces (η3-pentadienyl)Ir(PEt3)2 (1) or (η3-2,4-dimethylpentadienyl)Ir(PEt3)2(2) in high yield. In solution, compound 1 exists as a 70:30 equilibrium mixture of anti-pentadienyl (1a) and syn-pentadienyl (1s) isomers, while compound 2 exists exclusively in the anti form. Both 1a and 2 undergo a low-energy fluxional process that exchanges the ends of the anti-η3-pentadienyl ligand via an 18e- η5-pentadienyl intermediate. Treatment of 1 and 2 with Lewis bases, L, leads to the formation of known (pentadienyl)Ir(PEt3)2L complexes. In particular, addition of 1 equiv of PEt3 to 1 and 2 produces ((1,4,5-η)pentadienyl)Ir(PEt3)3 and mer-CH=C(Me)CH=C(Me)CH2Ir(PEt3)3(H), respectively, while addition of CO produces ((1,4,5-η)-pentadienyl)Ir(PEt3)2(CO)/((1-3-η)-pentadienyl)Ir(PEt3)2(CO) and ((1,4,5-η)-2,4-dimethylpentadienyl)Ir(PEt3)2(CO), respectively. Compounds 1 and 2 also react with Lewis acids. Hence, treatment with triflic acid produces (η5-pentadienyl)Ir(PEt3)2(H)+O3SCF3-(3) and (η5-2,4-dimethylpentadienyl)Ir(PEt3)2(H)+O3SCF3-(4), respectively, while treatment with methyl triflate generates (η5-pentadienyl)Ir(PEt3)2(CH3)+-O3SCF3-(5) and (η5-2,4-dimethylpentadienyl)Ir(PEt3)2(CH3)+O3SCF3-(6), respectively. Compounds 3–6 adopt unsymmetrical structures in which one phosphine resides under a pentadienyl edge while the other phosphine is situated under the pentadienyl mouth. Compound 3 undergoes a fluxional process in solution that involves rotation of the η5-pentadienyl ligand with respect to the Ir(PEt3)2(H) fragment. Under this process, the two phosphines exchange positions and the two ends of the pentadienyl ligand become equivalent. Compounds 3–6 react with bis(triphenylphosphine)nitrogen(1+) chloride (PPN+Cl-), a source of Cl-, to produce (syn-η3-pentadienyl)Ir(PEt3)2(H)(Cl) (7), (syn-η3-2,4-dimethylpentadienyl)Ir(PEt3)2(H)(Cl) (8), (syn-η3-pentadienyl)Ir(PEt3)2(CH3)(Cl) (9), and (syn-η3-2,4-dimethylpentadienyl)Ir(PEt3)2(CH3)(Cl) (10), respectively. In these compounds, the phosphine ligands are situated trans to the pentadienyl ligands.
AB - Treatment of [ClIr(PEt3)2]2with potassium pentadienide or potassium 2,4-dimethylpentadienide produces (η3-pentadienyl)Ir(PEt3)2 (1) or (η3-2,4-dimethylpentadienyl)Ir(PEt3)2(2) in high yield. In solution, compound 1 exists as a 70:30 equilibrium mixture of anti-pentadienyl (1a) and syn-pentadienyl (1s) isomers, while compound 2 exists exclusively in the anti form. Both 1a and 2 undergo a low-energy fluxional process that exchanges the ends of the anti-η3-pentadienyl ligand via an 18e- η5-pentadienyl intermediate. Treatment of 1 and 2 with Lewis bases, L, leads to the formation of known (pentadienyl)Ir(PEt3)2L complexes. In particular, addition of 1 equiv of PEt3 to 1 and 2 produces ((1,4,5-η)pentadienyl)Ir(PEt3)3 and mer-CH=C(Me)CH=C(Me)CH2Ir(PEt3)3(H), respectively, while addition of CO produces ((1,4,5-η)-pentadienyl)Ir(PEt3)2(CO)/((1-3-η)-pentadienyl)Ir(PEt3)2(CO) and ((1,4,5-η)-2,4-dimethylpentadienyl)Ir(PEt3)2(CO), respectively. Compounds 1 and 2 also react with Lewis acids. Hence, treatment with triflic acid produces (η5-pentadienyl)Ir(PEt3)2(H)+O3SCF3-(3) and (η5-2,4-dimethylpentadienyl)Ir(PEt3)2(H)+O3SCF3-(4), respectively, while treatment with methyl triflate generates (η5-pentadienyl)Ir(PEt3)2(CH3)+-O3SCF3-(5) and (η5-2,4-dimethylpentadienyl)Ir(PEt3)2(CH3)+O3SCF3-(6), respectively. Compounds 3–6 adopt unsymmetrical structures in which one phosphine resides under a pentadienyl edge while the other phosphine is situated under the pentadienyl mouth. Compound 3 undergoes a fluxional process in solution that involves rotation of the η5-pentadienyl ligand with respect to the Ir(PEt3)2(H) fragment. Under this process, the two phosphines exchange positions and the two ends of the pentadienyl ligand become equivalent. Compounds 3–6 react with bis(triphenylphosphine)nitrogen(1+) chloride (PPN+Cl-), a source of Cl-, to produce (syn-η3-pentadienyl)Ir(PEt3)2(H)(Cl) (7), (syn-η3-2,4-dimethylpentadienyl)Ir(PEt3)2(H)(Cl) (8), (syn-η3-pentadienyl)Ir(PEt3)2(CH3)(Cl) (9), and (syn-η3-2,4-dimethylpentadienyl)Ir(PEt3)2(CH3)(Cl) (10), respectively. In these compounds, the phosphine ligands are situated trans to the pentadienyl ligands.
UR - https://www.scopus.com/pages/publications/0001510532
U2 - 10.1021/om00004a021
DO - 10.1021/om00004a021
M3 - Article
AN - SCOPUS:0001510532
SN - 0276-7333
VL - 14
SP - 1667
EP - 1673
JO - Organometallics
JF - Organometallics
IS - 4
ER -