Synthesis and Characterization of Chloro‐ and Alkyliron Complexes with N‐Donor Ligands and Their Reactivity towards CO2

Publisher: John Wiley & Sons Inc

E-ISSN: 1099-0682|2015|30|5066-5073

ISSN: 1434-1948

Source: EUROPEAN JOURNAL OF INORGANIC CHEMISTRY (ELECTRONIC), Vol.2015, Iss.30, 2015-10, pp. : 5066-5073

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Abstract

AbstractNew iron(II) compounds with N‐donor ligands [2,2′‐bipyridine (bpy) and 2‐(2‐pyridyl)ethylamine (pyea)] were synthesized, and their reactivity with carbon dioxide was investigated. The reactions of Fe(bpy)(pyea)Cl2 (1) with CO2 (0.9 MPa) afforded the carbamato derivative Fe(bpy)(pyea‐CO2)Cl2 (2), which reacted with CH3Li to afford the monomethyl carbamato complex Fe(bpy)(pyea‐CO2)ClCH3 (3), an example of a carbamato species that is stable over a carboxylato moiety. Fe[(bpy)(pyea)](CH3)2 (4), obtained by reaction of 1 with CH3Li, was treated with CO2 (0.3–0.5 MPa) to afford the dicarboxylato species Fe[(bpy)(pyea)](O2CCH3)2 (5), which provides evidence of normal double insertion of CO2 into the Fe–C bond. The reaction of 5 with HCl afforded 1 and CH3–CO2H, which confirmed the mode of bonding of the –O2CCH3 moiety to the Fe center. To verify the preference of insertion of CO2 into the Fe–C or the Fe–N bond, 1 was treated with MeLi (1 equiv.), and Fe(bpy)(pyea)Cl(CH3) (6) was isolated as a low‐melting solid. The latter was treated with CO2 (0.5 MPa), and the product of insertion into the Fe–CH3 bond was observed as the only carboxylate (7). The faster insertion into the Fe–CH3 bond is explained by the fact that the N donor is quaternarized upon interaction with the metal center and has no free electrons available to interact with the C acceptor of the cumulene molecule; thus, more‐forcing conditions (0.9 MPa) are required for the insertion to occur.

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