Exploring the coordination modes of pyrrolyl ligands in bis(imido) uranium(vi) complexes

Abstract

The preparation of a family of bis(imido) uranium(VI) complexes stabilized by mono- and bidentate pyrrolyl ancillary ligands is described. X-ray crystallographic studies of dipyrrolylmethane (dpm) derivatives show that the pyrrolyl coordination mode in these uranium(VI) ions is unexpected in comparison to analogous transition metal and lanthanide chemistry. The ability of the coordinated pyrrolyl moieties to undergo pyrrolyl isomerization has also been explored and demonstrates reactivity that is unique from structurally similar uranium(VI)-bis(cyclopentadienyl) derivatives.

Multi-electron reduction facilitated by a trianionic pyridine(diimine) ligand

“…These bonds are in agreement with other high-valent uranium-imido bonds, [29][30][31] and are longer than those reported for U(VI) trans-bis(imido) species, which have U-N bond lengths of 1.81-1.88 Å. [32][33][34][35][36][37] The U-N bonds in 2 most closely match with those for the uranium(V) bis(imido), U(NDipp) 2 Cl( t Bu 2 bpy) 2 (Dipp = 2,6-diisopropylphenyl), reported by Boncella, with U-N distances of 1.977(4) and 1.980(4) Å. 29 The arrangement of the imido substituents in 2 enforces an N-U-N angle of 154.2(2)1, smaller than those noted for all other uranium bis(imido) complexes (161.10(19)-180.0(3)1).…”

“…29 The arrangement of the imido substituents in 2 enforces an N-U-N angle of 154.2(2)1, smaller than those noted for all other uranium bis(imido) complexes (161.10(19)-180.0(3)1). 29,[32][33][34][35][36][37] This is most likely due to steric pressure imparted by the Cp* ring. The U-N imido -C bond angles (169.1(5)1 and 170.1(5)1) are nearly linear, indicative of nitrogen lone pair bonding to uranium.…”

Synthesis and Reduction of Uranium(V) Imido Complexes with Redox‐Active Substituents

“…[4][5][6][7][8] The studyo fU À Nm ultiple bondingi sm ore limited, although it has recently achieved milestone discoveries in the isolation of the first exampleso ft erminal molecular uranium nitride, [9][10][11] terminal parenti mido, [12] and uranium tris(imido) moieties. [13,14] Presently,t here are an umber of high-valent uraniumb is(imido) complexes reported in the literature, [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] as well as uranium mono(imido)c omplexes in the uranium + 4, [24][25][26][27][28][29][30][31][32][33][34][35] + 5, [36][37][38][42][43][44][45][46] and + 6 [36,37,…”

“…The study of U−N multiple bonding is more limited, although it has recently achieved milestone discoveries in the isolation of the first examples of terminal molecular uranium nitride, terminal parent imido, and uranium tris(imido) moieties . Presently, there are a number of high‐valent uranium bis(imido) complexes reported in the literature, as well as uranium mono(imido) complexes in the uranium +4, +5, and +6 oxidation states.…”

Switchable π-coordination and C–H metallation in small-cavity macrocyclic uranium and thorium complexes

“…28,29 Although pyrrolide ligands can coordinate to the metal centre in a k 1 mode through the N atom or in a k 5 mode, similar to classical cyclopentadienyl coordination to a metal, the k 1 mode is by far the more common of the two. 15,[30][31][32][33][34][35][36][37] The trans-calix[2]benzene[2]pyrrolide, (L) 2À , combines two pyrrolide heterocycles with two aryl rings connected via dimethylmethane linkers. 38 The lack of extended conjugation in this macrocycle, as compared to porphyrins, grants it a large degree of exibility, allowing the possibility of either sor p-bonding of the ligand to the metal centre through either the pyrrolide or arene.…”