81971-46-2Relevant articles and documents
Control of η2-Arene Coordination and C-H Bond Activation by Cyclopentadienyl Complexes of Rhodium
Belt, Simon T.,Dong, Lingzhen,Duckett, Simon B.,Jones, William D.,Partridge, Martin G.,Perutz, Robin N.
, p. 266 - 269 (1991)
The selectivity for C-H bond activation vs. η2-coordination of arenes with 5-C5R5)Rh(PMe3)> fragments (R = Me, H) is subject to control by the thermodynamic stability of the resulting η2-arene complex; the preference fo
Formation of η2-side-bonded aryl nitrile complexes from 4-metallaisoxazolin-5-one species and their application in the thermal and photochemical activation of C-H bonds
Chetcuti, Peter A.,Knobler, Carolyn B.,Hawthorne, M. Frederick
, p. 650 - 660 (2008/10/08)
Thermolysis of the 4-metallaisoxazolin-5-one metallacycles (η5-C5H5)(PPh3)Ir{η 2-(Ar)NOC(=0)-} (Ar = p-ClC6H4 (1a), p-FC6H4 (1b)) at 110°C for 24 h in toluene leads to the novel side-bonded nitrile complexes (η5-C5H5)(PPh3)Ir(η 2-NCAr) (Ar = p-ClC6H4 (7a), p-FC6H4 (7b)) by an intramolecular process involving loss of CO2 from 1a and 1b. The stability of 7a and 7b and their mode of formation suggest that these complexes are best described as the product of oxidative addition of an Ir(I) metal fragment into a CN triple bond. The single-crystal X-ray diffraction study of 7a is reported and the structure discussed. Crystallographic data for 7a: space group Pcan (standard setting Pbcn); a = 10.638 (2) A?, b = 14.298 (3) A?, c = 33.310 (5) A?, V = 5066 A?3, and Z = 8. Thermolysis, in the dark, of the metallacycle (η5-C5Me5)-(CO)Ir{η 2-C(p-ClC6H4)NOC(=O)-} (9) in benzene at 50°C for 5 weeks leads to the C-H activation product (η5-C5Me5)Ir(CO)(H)(C6H 5) (11) in 90% yield by 1H NMR. The dimer [(η5-C5Me5)Ir(μ-CO)2 (13) was also identified in 8.6% yield. When 9 was warmed in cyclohexane for 5 weeks under the same conditions, the iridium cyclohexyl hydride (η5-C5Me5)Ir(CO)(H)(C6H 11) (14) was obtained in 3% yield and dimer 13 was obtained in 65% yield. These thermal reactions are shown to proceed via the side-bonded nitrile intermediate (η5-C5Me5)(CO)Ir(η2-NCC 6H4Cl) (16) which has been isolated, characterized, and shown to independently activate benzene C-H bonds at 50°C. A single-crystal X-ray diffraction study of 16 is reported and the crystal structure discussed. Crystallographic data for 16: space group P21/a; a = 7.859 (2) A?, b = 20.010 (4) A?, c = 11.721 (2) A?, β = 108.757 (4)°, V = 1745 A?3, and Z = 4. Complexes 16 and 9 could be readily decomposed under mild photochemical conditions in benzene and cyclohexane to yield the iridium phenylhydride product 11 and the iridium cyclohexylhydride product 14 in high yield. Thermolysis of (η5-C5Me5)(PMe3)Rh{η 2-C(p-FC6H4)NOC(=O)-} (10) for 3 days in benzene at 50°C leads to (η5-C5Me5)(PMe3)Rh(η 2-NCC6H4F) (18) in 80% yield and to (η5-C5Me5)(PMe3)Rh(C 6H5)(H) in 13% yield. When the reaction was carried out in toluene under these conditions, 18 was obtained in 60% yield and the C-H activation products (η5-C5Me5)(PMe3)Rh(H)(p-C 6H4CH3) and (η5-C5Me5)(PMe3)Rh(H)(m-C 6H4CH3) were obtained in 2% and 4% yields, respectively.
