Addition of Amines to a Carbonyl Ligand: Syntheses, Characterization, and Reactivities of Iridium(III) Porphyrin Carbamoyl Complexes

Treatment of (carbonyl)chloro(meso-tetra-p-tolylporphyrinato)iridium(III), (TTP)Ir(CO)Cl (1), with excess primary amines at 23 °C in the presence of Na2CO3 produces the trans-amine-coordinated iridium carbamoyl complexes (TTP)Ir(NH2R)[C(O)NHR] (R = Bn (2a), n-Bu (2b), i-Pr (2c), t-Bu (2d)) with isolated yields up to 94%. The trans-amine ligand is labile and can be replaced with quinuclidine (1-azabicyclo[2.2.2]octane, ABCO), 1-methylimidazole (1-MeIm), triethyl phosphite (P(OEt)3), and dimethylphenylphosphine (PMe2Ph) at 23 °C to afford the hexacoordinated carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (for R = Bn: L = ABCO (3a), 1-MeIm (4a), P(OEt)3 (5a), PMe2Ph (6a)). On the basis of ligand displacement reactions and equilibrium studies, ligand binding strengths to the iridium metal center were found to decrease in the order PMe2Ph \u3e P(OEt)3 \u3e 1-MeIm \u3e ABCO \u3e BnNH2 ≫ Et3N, PCy3. The carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (L = RNH2 (2a,b), 1-MeIm (4a)) undergo protonolysis with HBF4 to give the cationic carbonyl complexes [(TTP)Ir(NH2R)(CO)]BF4 (7a,b) and [(TTP)Ir(1-MeIm)(CO)]BF4 (8), respectively. In contrast, the carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (L = P(OEt)3 (5a), PMe2Ph (6a,c)) reacted with HBF4 to afford the complexes [(TTP)Ir(PMe2Ph)]BF4 (9) and [(TTP)IrP(OEt)3]BF4 (10), respectively. The carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (L = RNH2 (2a–d), 1-MeIm (4a), P(OEt)3 (5b), PMe2Ph (6c)) reacted with methyl iodide to give the iodo complexes (TTP)Ir(L)I (L = RNH2 (11a–d), 1-MeIm (12), P(OEt)3(13), PMe2Ph (14)). Reactions of the complexes [(TTP)Ir(PMe2Ph)]BF4 (9) and [(TTP)IrP(OEt)3]BF4 (10) with [Bu4N]I, benzylamine (BnNH2), and PMe2Ph afforded (TTP)Ir(PMe2Ph)I (14), (TTP)Ir[P(OEt)3]I (13), [(TTP)Ir(PMe2Ph)(NH2Bn)]BF4 (16), and trans-[(TTP)Ir(PMe2Ph)2]BF4 (17), respectively. Metrical details for the molecular structures of 4a and17 are reported

Unexpected coupling of Cp and two RNC ligands at a {Mo-2(mu-SMe)(3)} nucleus

cited By 21International audienceReaction of the bis-isonitrile complex [Mo2-Cp2(μ-SMe)3(t-BuNC)2] (BF4) (1) with n-BuLi (in hexane) produced the dealkylated derivative [Mo2Cp2(μ-SMe)3-(t-BuNC)(CN)] (2) in quantitative yield. However, upon treatment with either NaOH (suspension) or (Me4N)OH (in MeOH), 1 was converted into a mixture of 2 and the μ-alkylidyne species [Mo2Cp(μ-SMe)3μ-(η5-C5 H4)(t-BuN)-CN(t-Bu)C] (3), in which a deprotonated Cp and both isonitrile ligands of 1 are now linked by new carbon-carbon and carbon-nitrogen bonds

Coupling of Isocyanide and μ-Aminocarbyne Ligands in Diiron Complexes Promoted by Hydride Addition

The diiron \u3bc-aminocarbyne complexes [Fe2{\u3bc-CN(Me)(R)}(\u3bc- CO)(CO)(CNR\u2032)(Cp)2][SO3CF3] (R = R\u2032 = Xyl, 2a; R = Xyl, R\u2032 = Me, 2b; R = Xyl, R\u2032 = But, 2c; R = Xyl, R\u2032 = p-C6H4CF3, 2d; R = Me, R\u2032 = Xyl, 2e; Xyl = 2,6-Me2C6H3), containing an isocyanide ligand, have been obtained via CO replacement with the appropriate CNR\u2032 ligand from [Fe2{\u3bc-CN(Me)(R)}(\u3bc- CO)(CO)2(Cp)2][SO3CF3] (R = Xyl, 1a; R = Me, 1b). Compound 2a, upon treatment with NaBH4 and heating at reflux temperature in THF solution, is transformed into the aminocarbene 12aldimine [Fe2{\u3bc-\u3b71(C):\u3b71(N)-CN(Me)(Xyl)CH\ue0c8N(Xyl)}(\u3bc-CO)2(Cp)2] (3) in moderate yield. The reactions occurs via formation of the formimidoyl complex [Fe2{\u3bc-CN(Me)(Xyl)}(\u3bc-CO)(CO){C- (H)\ue0c8NXyl}(Cp)2] (4a), which has been isolated by reacting 2a with NaBH4 at 0 \ub0C. Likewise, the formimidoyl complex [Fe2{\u3bc-CN(Me)(R)}(\u3bc-CO)(CO){C(H)\ue0c8NR\u2032}(Cp)2] (R = Xyl, R\u2032 = Me, 4b; R = Me, R\u2032 = Xyl, 4c) have been obtained from 2b,e, respectively, upon reaction with NaBH4, but these complexes do not convert into the aminocarbene 12aldimine complexes analogous to 3. Reactions of 2a with other nucleophiles have been investigated, without obtaining any product similar to 3. Complex 2a reacts with NaCN or with LiPPh2, resulting in isocyanide displacement and formation of [Fe2{\u3bc-CN(Me)(Xyl)}(\u3bc- CO)(CO)(CN)(Cp)2] (5) and [Fe2 {\u3bc-CN(Me)(Xyl)}(\u3bc-CO)(CO)(PPh2)(Cp)2] (6), respectively. Addition of the organocopper reagent Li2CuCNMe2 to 2a affords the acyl complex [Fe2{\u3bc-CN(Me)(Xyl)}(\u3bc-CO){C(O)Me}(CNXyl)(Cp)2] (7). The thiocarbyne complex [Fe2{\u3bc-CSMe}(\u3bc-CO)(CO)(CNXyl)(Cp)2][SO3CF3] (8), which shows analogies with 2a, reacts with NaBH4, affording the carbene derivative [Fe2 \u3bc-{C(SMe)(H)}(\u3bc-CO)(CO)(CNXyl)(Cp)2] (9). The molecular structures of 2a and 3 have been determined by X-ray diffraction studies