Metallaaromatic Systems
Electronic effects of substituents on the stability of the iridanaphthalenes. Iridanaphthalene complexes are synthesized from the corresponding methoxy(alkenyl)carbeneiridium compounds. The electronic character of the substituents on the 6-position of the metallanaphthalene ring is crucial from the point of view of the stability of the iridanaphthalene, [IrCp*{C(OMe)CHC(o-C6H4)(Ph)}(PMe3)]PF6, vs. its transformation to the corresponding indanone derivatives. Stability studies of the iridanaphthalene compounds revealed that strong electron donor substituents (–OMe) stabilize the iridanaphthalene, while weak electron donor (–Me) and electron withdrawing (–NO2) groups favor the formation of indanone derivatives. Two possible indanone isomers can be obtained in the conversion of the unstable iridanaphthalene complexes and a mechanism for the formation of these isomers is proposed.
Formation of Indanone from an Iridanaphthalene Complex. The first example of evolution of an iridanaphthalene into an indanone through an intermediate indenyl is reported, serving as a good example of starting material to obtain indanones. Two new iridanaphthalenes are obtained by intramolecular C–H activation of a phenyl ring of a carbene ligand in [IrCp*{═C(OMe)CH═CPh2}(L)]PF6 (L = PPh2Me, PMe3) complexes. It is demonstrated that these iridanaphthalene complexes can undergo a thermal reaction to give indenyl complexes and 3-phenylindanone.
