SYNTHESIS AND REACTIONS OF ENE-HYDRAZONE DIPHOSPHINE IRIDIUM COMPLEXES AND RELATED SPECIES

Treatment of the azine diphosphine Z,Z-PPh2CH2C(Bu-t)=N-N=C(Bu')CH2PPh 2 I with [IrCl(CO)(2)(H2NC6H4Me-4)] in benzene gave the ene-hydrazone diphosphine iridium(III) hydride [IrH(Cl)(CO){PPh2CH=C(Bu-t)N-N=C(Bu-t )-CH2PPh2}], 1, which isomerised reversibly to the ionic square planar iridium(I) complex [Ir(CO){PPh2CH2C-(Bu-t)=N-N=C(Bu-t)CH2PPh2}] Cl 2a , containing an azine diphosphine. Treatment of 1 with NEt3 gave the n eutral ene-hydrazone diphosphine iridium(I) complex [Ir(CO){PPh2CH=C(B u-t)N-N=C(Bu-t)CH2PPh2}] 3 which is reactive and undergoes oxidative a ddition of H-2 to give the iridium(III) dihydride r,cis-[IrH2(CO){PPh2 CH=C(Bu-t)N-N=C(Bu-t)CH2PPh2}] 4 and oxidative addition of MeI to give the methyliridium(III) complex [IrMe(I)-(CO){PPh2CH=C(Bu-t)N-N=C(Bu-t )CH2PPh2}] 5. It reacted rapidly with olefins or acetylenes (L), i.e. N-methyl-maleimide, ethene or dimethyl acetylenedicarboxylate, to give the five-co-ordinate adducts [Ir(CO)L {PPh2CH=C(Bu-t)N-N=C(Bu-t)CH2PP h2}], 6a, 6b or 6c, respectively, also with O-2 to give the eta(2)-dio xygen adduct O)-(eta(2)-O-2){PPh2CH=C(Bu-t)N-N=C(Bu-t)CH2PPh2}] 7. Tre atment of 3 with 1 mol of picric acid protonated the ene-hydrazone dip hosphine backbone to give the azine diphosphine iridium(I) salt PPh2CH 2C(Bu-t)=N-N=C(Bu-t)CH2PPh2}][OC6H2(NO2)(3)] 2b. The N-methylmaleimide adduct 6a was similarly protonated to give the corresponding azine di phosphine iridium(I) salt [Ir(CO)(eta(2)-COCH=CHCONMe) Ph2CH2C(Bu-t)=N -N=C(Bu-t)-CH2PPh2}][OC6H2(NO2)(3)] 8. Complex 1 was protonated by HCl to give the corresponding azine diphosphine iridium(III) salt [IrH(Cl )(CO){PPh2CH2C(Bu-t)=N-N=C(Bu-t)CH2PPh2}]Cl 9a, which is converted int o 3 when treated with NEt3. The H-1, C-13 and P-31 NMR and some IR dat a are given.