Photolysis, Thermolysis, and Reduction of a Uranium Azide Complex Supported by a Double-Layer N–P Ligand

Abstract

A double-layer N–P ligand-supported uranium azide complex 2 ([N­(CH2CH2NP i Pr2)3UN3]2) was synthesized by the reaction of a uranium precursor [N­(CH2CH2NP i Pr2)3UCl] (1) with NaN3. Photolysis and thermolysis of complex 2 led to the formation of complex 3 ([N­(CH2CH2NP i Pr2)2(CH2CH2NP i Pr2N)­U]2); a uranium nitride intermediate is proposed in this process. The alkali metal-capped uranium nitride complexes M­{UIV(μ-N)­UIV} (4: M = Li, 5: M = Na) and di-imido bridged complex M2{UIV(μ-NH)2UIV} (6: M = K) were formed by the reduction of complex 2 with different alkali metals (Li, Na, and K). These results reveal the important role of the supporting ligand in actinide organometallic chemistry and also show that uranium nitride complexes can be modulated by different decomposition reactions of the uranium azide precursor.

Progress in the chemistry of molecular actinide-nitride compounds

“…The X-ray diffraction structures of 34-Li and 34-Na are similar and both complexes exhibit an alkali metal-capped uranium nitride unit, MU IV –N–U IV (M = Li, Na). 84 The U–N–U bond angle in complex 34-Na (127.8(2)°) is bent when compared to 34-Li (146.6(3)°), which could arise from the bound THF molecule coordinated to the Na cation in 34-Na . Photolysis and thermolysis of [(U IV (Tren NP )) 2 (μ-N 3 ) 2 ] ( 34a ), led to a U( iv )/U( iv ) ligand-insertion product, [U IV (N(CH 2 CH 2 NP i Pr 2 ) 2 (CH 2 CH 2 NP i Pr 2 N)] 2 ( 35 ) (Scheme 7), in which a uranium-nitride intermediate was proposed by the authors for its formation.…”

“…Subsequent addition of metallic Li or sodium (Na) afforded the U( iv )/U( iv ) bridging nitride complexes, [Li(U IV (Tren NP )) 2 (μ-N)] ( 34-Li ) and [Na(THF)(U IV (Tren NP )) 2 (μ-N)] ( 34-Na ), respectively (Scheme 7). 84 In contrast, the reduction with metallic K generated the U( iv )/U( iv ) complex, [K 2 (U IV (Tren NP ))(μ-NH) 2 ], with two bridging imido (μ-NH 2− ) ligands linking the two uranium centers, while coordinated to the K cations. The X-ray diffraction structures of 34-Li and 34-Na are similar and both complexes exhibit an alkali metal-capped uranium nitride unit, MU IV –N–U IV (M = Li, Na).…”

“…In contrast, the reduction with metallic K generated the U(IV)/ U(IV) complex, [K 2 (U IV (Tren NP ))(m-NH) 2 ], with two bridging imido (m-NH 2− ) ligands linking the two uranium centers, while coordinated to the K cations. The X-ray diffraction structures of 34-Li and 34-Na are similar and both complexes exhibit an alkali metal-capped uranium nitride unit, MU IV -N-U IV (M = Li, Na) 84. The U-N-U bond angle in complex 34-Na(127.8(2)°) is bent when compared to 34-Li (146.6(3)°), which could arise from the bound THF molecule coordinated to the Na cation in 34-Na.…”

“…or sodium (Na) afforded the U(IV)/U(IV) bridging nitride complexes, [Li(U IV (Tren NP )) 2 (m-N)] (34-Li) and [Na(THF)(U IV (Tren NP )) 2 (m-N)] (34-Na), respectively (Scheme 7) 84. In contrast, the reduction with metallic K generated the U(IV)/ U(IV) complex, [K 2 (U IV (Tren NP ))(m-NH) 2 ], with two bridging imido (m-NH 2− ) ligands linking the two uranium centers, while coordinated to the K cations.…”

Synthesis and reactivity of a uranium(iv) complex supported by a monoanionic nitrogen–phosphorus ligand

“…E-mail: zcq@nju.edu.cn donor coordination sites. Based on our continuing interest in uranium chemistry supported by N-P ligands, [37][38][39][40][41][42][43] herein, we have designed a new monoanionic double-layer N-P ligand with a pendant dimethylamino group as an additional coordination site (L3, Fig. 1).…”