Rhodium and iridium complexes with 2-(diphenylphosphanyl)anilido ligands: reactions with phenylacetylene and dimethyl acetylenedicarboxylate

Treatment of [Ir(CO)(PPh3)('PNMe')] ('PNME'=2-Ph2PC6H4NMe-) with phenylacet ylene resulted in oxidative addition and opening of the chelate ring to aff ord mono- and bis-(alkynyl) derivatives, [IrH(C=CPh)(CO)(PPh3)('PNMe')] 1 a nd [IrH(C=CPh)(2)(CO)(PPh3)(eta(1)-'PN(Me)H')] 2, respectively. Complex 2 e xists as two isomers with trans-located phosphane ligands and cis- or trans - coordinated alkynyl groups. The minimum values of the spin-lattice relaxa tion times, T ((min))(1), observed for the hydride ligands of the two isome rs ruled out the possibility of short IrH ... HN contacts in 2. Combination of [Ir(CO)(PPh3)('PNMe')] with dimethyl acetylenedicarboxylate (dmad) gave the irida(III)cyclopropene-like complex [Ir{C-2(CO2Me)(2)}(CO)(PPh3)('PNMe ')] 3 as the expected 1:1 adduct. In contrast, [Rh(CO)(PPh3)('PNMe')] and d mad interacted by insertion of the activated alkyne into the Rh-N bond, for ming the seven-membered metallaheterocycle[Rh{C(CO2Me)=C(CO2Me)N(Me)C6H4PPh 2-2}(CO)(PPh3)] 4. [Ir(CO)(PPh3)('PNH')] ('PNH'=2-Ph2PC6H4NH-) and dmad rea cted to initially produce a mixture of metallacyclic [Ir{C-2(CO2Me)(2)}(CO) (PPh3)('PNH')] 5 and unchanged starting materials. Subsequent treatment wit h methanol resulted in the formation of the iridium(III) complex [Ir{C(O)OM e}{C(CO2Me)=CH[C(O)OMe]}(PPh3) ('PNH')] 6, which X-ray crystallography show ed to contain a chelating vinyl ligand featuring substantial carbenoid char acter.