1,4‐Dicyanobenzene as a Scaffold for the Preparation of Bimetallic Actinide Complexes Exhibiting Metal–Metal Communication

Reaction of two equivalents of [(C 5 Me 4 Et) 2 U(CH 3 )(Cl)] ( 6 ) or [(C 5 Me 5 ) 2 Th(CH 3 )(Br)] ( 7 ) with 1,4‐dicyanobenzene leads to the formation of the novel 1,4‐phenylenediketimide‐bridged bimetallic organoactinide complexes [{(C 5 Me 4 Et) 2 (Cl)U} 2 (μ‐{NC(CH 3 )‐C 6 H 4 ‐(CH 3 )CN})] ( 8 ) and [{(C 5 Me 5 ) 2 (Br)Th} 2 (μ‐{NC(CH 3 )‐C 6 H 4 ‐ (CH 3 )CN})] ( 9 ), respectively. These complexes were structurally characterized by single‐crystal X‐ray diffraction and NMR spectroscopy. Metal–metal interactions in these isovalent bimetallic systems were assessed by means of cyclic voltammetry, UV‐visible/NIR absorption spectroscopy, and variable‐temperature magnetic susceptibility. Although evidence for magnetic coupling between metal centers in the bimetallic U IV /U IV (5f 2 –5f 2 ) complex is ambiguous, the complex displays appreciable electronic communication between the metal centers through the π system of the dianionic diketimide bridging ligand, as judged by voltammetry. The transition intensities of the f–f bands for the bimetallic U IV /U IV system decrease substantially compared to the related monometallic ketimide chloride complex, [(C 5 Me 5 ) 2 U(Cl){‐NC(CH 3 )‐(3,4,5‐F 3 ‐C 6 H 2 )}] ( 11 ). Also reported herein are new synthetic routes to the actinide starting materials [(C 5 Me 4 Et) 2 U(CH 3 )(Cl)] ( 6 ) and [(C 5 Me 5 ) 2 Th(CH 3 )(Br)] ( 7 ) in addition to the syntheses and structures of the monometallic uranium complexes [(C 5 Me 4 Et) 2 UCl 2 ] ( 3 ), [(C 5 Me 4 Et) 2 U(CH 3 ) 2 ] ( 4 ), [(C 5 Me 4 Et) 2 U{‐NC(CH 3 )‐C 6 H 4 ‐CN} 2 ] ( 10 ), and 11 .