An N-Tethered Uranium(III) Arene Complex and the Synthesis of an Unsupported U–Fe Bond

5 years ago

An N-Tethered Uranium(III) Arene Complex and the Synthesis of an Unsupported U–Fe Bond

Alan G. Goos, Alejandro J. Metta-Magaña, J. Rolando Aguilar-Calderón, Skye Fortier, Cristian E. Botez, Bess Vlaisavljevich

Amination of 2,2″-dibromo-p-terphenyl with 2,6-diisopropylaniline, through Pd mediated cross coupling, yields the p-terphenyl bis(aniline) ligand H₂L^Ar. Deprotonation of H₂L^Ar with excess KH generates the dianion [K(DME)₂]₂L^Ar as a dark red solid. Treatment of [K(DME)₂]₂L^Ar with UI₃(dioxane)_1.5 produces the mononuclear U(III) complex L^ArU(I)(DME) (1). Subsequent addition of the nucleophilic metal anion [CpFe(CO)₂]⁻ (Fp^–) gives the bimetallic U(III) compound L^ArU(Fp) (2) in modest yield which features a rare instance of an unsupported U–M bond. Inspection of the metrical parameters of the solid-state structures of 1·DME and 2·0.5DME from X-ray crystallographic analyses show a seemingly η⁶-interaction between the uranium and the terphenyl ligand (1: U1–C_centroid = 2.56 Å; 2: U1–C_centroid = 2.45 Å), spatially imposed as a consequence of the anilide N-donor atom coordination. Furthermore, the U–Fe bond length in 2 (U1–Fe1 = 2.9462(3) Å) is consistent with a metal–metal single bond. Notably, electronic structure analyses by CASPT2 calculations instead suggest that electrostatic, and not covalent, interactions dominate between the U–arene systems in 1 and 2 and between the U–Fe bond in the latter.

Publisher URL: http://dx.doi.org/10.1021/acs.organomet.7b00429

DOI: 10.1021/acs.organomet.7b00429