title: Mild, reversible reaction of iridium(III) amido complexes with carbon dioxide.
abstract: Unlike some other Ir(III) hydrides, the aminopyridine complex [(2-NH(2)-C(5)NH(4))IrH(3)(PPh(3))(2)] (1-PPh(3)) does not insert CO(2) into the Ir-H bond. Instead 1-PPh(3) loses H(2) to form the cyclometalated species [(κ(2)-N,N-2-NH-C(5)NH(4))IrH(2)(PPh(3))(2)] (2-PPh(3)), which subsequently reacts with CO(2) to form the carbamato species [(κ(2)-O,N-2-OC(O)NH-C(5)NH(4))IrH(2)(PPh(3))(2)] (10-PPh(3)). To study the insertion of CO(2) into the Ir-N bond of the cyclometalated species, a family of compounds of the type [(κ(2)-N,N-2-NR-C(5)NH(4))IrH(2)(PR'(3))(2)] (R = H, R' = Ph (2-PPh(3)); R = H, R' = Cy (2-PCy(3)); R = Me, R' = Ph (4-PPh(3)); R = Ph, R' = Ph (5-PPh(3)); R = Ph, R' = Cy (5-PCy(3))) and the pyrimidine complex [(κ(2)-N,N-2-NH-C(4)N(2)H(3))IrH(2)(PPh(3))(2)] (6-PPh(3)) were prepared. The rate of CO(2) insertion is faster for the more nucleophilic amides. DFT studies suggest that the mechanism of insertion involves initial nucleophilic attack of the nitrogen lone pair of the amide on CO(2) to form an N-bound carbamato complex, followed by rearrangement to the O-bound species. CO(2) insertion into 1-PPh(3) is reversible in the presence of H(2) and treatment of 10-PPh(3) with H(2) regenerates 1-PPh(3), along with Ir(PPh(3))(2)H(5).
authors.affiliation: Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, USA.
authors.forename: Graham E
authors.initials: GE
authors.lastname: Dobereiner
authors.forename: Jianguo
authors.initials: J
authors.lastname: Wu
authors.forename: Michael G
authors.initials: MG
authors.lastname: Manas
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Schley
authors.forename: Michael K
authors.initials: MK
authors.lastname: Takase
authors.forename: Robert H
authors.initials: RH
authors.lastname: Crabtree
authors.forename: Nilay
authors.initials: N
authors.lastname: Hazari
authors.forename: Feliu
authors.initials: F
authors.lastname: Maseras
authors.forename: Ainara
authors.initials: A
authors.lastname: Nova
mesh_terms: D000577:Amides / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007495:Iridium / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D000577:Amides; D009942:Organometallic Compounds; D002245:Carbon Dioxide; D007495:Iridium