INTRAMOLECULAR C-H ACTIVATION AND OXIDATIVE ADDITION-REACTIONS OF IRIDIUM COMPLEXES CONTAINING ARYLAMINES WITH BULKY SUBSTITUENTS ON NITROGEN - X-RAY STRUCTURES OF [IR-I(C(6)H(4)CH(2)NET(2)-2-C,N)(COD)] AND [IR-III(C(6)H(4)CH(2)NET(CHME)-2-C,N,C')I(COD)] (COD EQUALS CYCLOOCTA-1,5-DIENE)

Square-planar iridium(I) complexes [Ir(C(6)H(4)CH(2)NRR') (cod)] (R = R' = Et; R = Me, R' = t-Bu; cod = cycloocta-1,5-diene) containing C,N- chelating arylamine ligands have been synthesized and characterized by NMR spectroscopy. An X-ray diffraction study of [Ir(C(6)H(4)CH(2)NEt( 2)-2-C,N) (cod)] shows a weak agostic interaction between the d(8) met al center and a methyl H atom of one ethyl group. An oxidative additio n reaction of this complex with MeI affords an Ir(III) complex [Ir(C(6 )H(4)CH(2)NEt(CHMe)-2-C,N,C')I(cod)] which results from an intramolecu lar methylene C-H activation process. This latter complex has been cha racterized with 2D NMR techniques and an X-ray diffraction study. The reactivity of the new iridium(I) complexes as well as [Ir(C(6)H(4)CH(2 )NMe(2)-2-C,N) (cod)], [Ir(1-C(10)H(6)NMe(2)-8-C,N) (cod)] and [Ir(C6H 4CH2N(Me)CH(2)CH(2)NMe(2)-2-C,N) (cod)] towards H-2 is reported; the d ifferent products obtained are discussed with reference to reaction pa thways influenced by the steric bulk on the nitrogen donor atom. Cryst als of [Ir(C(6)H(4)CH(2)NEt(2)-2-C,N)(cod)] are triclinic, space group P (1) over bar with unit-cell dimensions a = 9.154(1), b = 9.992(1), c = 10.846(1) Angstrom, (alpha = 93.46(1), beta = 113.03(1), gamma = 1 09.84(1)degrees, Z = 2, final R = 0.0234, wR = 0.0295 for 3465 reflect ions with I>2.5 sigma(I) and 197 parameters. Crystals of [Ir(C(6)H(4)C H(2)NEt(CHMe>-2-C,N,C')I(cod)] are triclinic, space group P (1) over b ar with dimensions a = 7.591(1), b = 11.406(1), c = 13.511(1) Angstrom , alpha = 65.63(1), beta = 88.34(1), gamma = 83.29(1)degrees, Z = 2, f inal R = 0.0319, wR = 0.0402 for 4236 reflections with I>2.5 sigma(I) and 228 parameters.