96411-83-5Relevant articles and documents
Inter- vs. intramolecular C-H activation: A C-H-Ir bridge in [IrH2(8-methylquinoline)L2]BF4 and a C-H + M → C-M-H reaction trajectory
Crabtree, Robert H.,Holt, Elizabeth M.,Lavin, Maryellen,Morehouse, Sheila M.
, p. 1986 - 1992 (2008/10/08)
The complexes [IrH2L′(PPh3)2]A (L′ = 8-methylquinoline, caffeine) each contain a C-H?Ir bridge, structurally characterized in the methylquinoline case (A = SbF6). The complex is monoclinic, space group P21/n with a = 19.221 (4) ?, b = 21.202 (11) ?, c = 11.079 (5) ?, β = 104.56 (3)°, and Z = 4. The final R factor was 4.6%. A structural measure of the strength of the bridging interaction was developed and used to systematize the data on this and 17 related structures. The results are used to construct a C-H + M → C-M-H reaction trajectory. On the basis of this trajectory, we propose that, for a given metal species capable of breaking C-H bonds, conformational and steric effects will play an important role in deciding whether cyclometalation or attack on external substrate such as an alkane will take place. In particular, it is suggested that sterically uncongested metal systems will favor the occurrence of alkane activation, rather than cyclometalation.
