Synthesis and structure of uranium(III) complexes with dihydrobis(pyrazolyl)borates

Continuous Shape Measures Study of the Coordination Spheres of Actinide Complexes – Part 1: Low Coordination Numbers

“…the covalent radii sum of 2.98 Å). [30] Other molecules that are quite close to the trigonal prism contain three bidentate ligands such as a dithiolate, [76] or ligands H-J (Scheme 6): [U III L H 3 ], [77] [U III L I 3 ], [78,79] [U IV L J 3 ]I, [80] all with the conformation K, in which the bidentate ligands occupy the edges of the trigonal prism parallel to the three-fold axis. Also analogous compounds with two bidentate ligands in the basal conformation L are worth being cited: [Th IV X 2 L I 2 ] (X = I, PHMes, PHPh), [81] and [(L J 2 U IV {OPy}) 2 μ-O].…”

“…The shape measures for the structures that are best described along the path between the elongated and compressed trigonal prisms are plotted in Figure 15a. The flattest trigonal prism, found in tris(diphenylbispyrazolylborate)uranium(III) [78] with r = 0.89 (or compressed a 29 % relative to the conventional reference fTPR-6 shape), is shown in Figure 16a. In the opposite direction, the most elongated trigonal prism (Figure 15b) is showcased by a dithiolate uranium(IV) complex, [76] with r = 1.15 (or elongated a 31 % to the conventional eTPR-6 shape).…”

Zur Elektronenstruktur hochsymmetrischer Verbindungen der f‐Elemente 44 [1]. Erstmalige parametrische Analyse des Absorptionsspektrums einer Molekülverbindung des trivalenten Urans: Tris[hydrotris(1‐pyrazolyl)borato]uran(III)

“…Im Falle homoleptischer LnL 3 ‐Verbindungen sind sowohl die durch den L = Tp‐Liganden hervorgerufenen Ligandenfeldstärken als auch die gefolgerten Kovalenzen erheblich geringer als die der mit L = [N(SiMe 3 ) 2 ] – 17, [OC 6 H 3 (2,6‐ t Bu 2 )] – 18 oder [C 5 H 4 (SiMe 3 )] – 12. Mit Kenntnis der phänomenologischen Parameter von UTp 3 könnte damit allenfalls die parametrische Analyse des Absorptionsspektrums von U{Ph 2 B(pz) 2 } 3 (trigonal‐prismatische Koordination des U III 52) gelingen. Die Parametrisierung der teilweise bereits vorhandenen Tieftemperatur‐Absorptionsspektren von U[N(SiMe 3 ) 2 ] 3 53, U[OC 6 H 3 (2,6‐ t Bu 2 )] 3 oder U[η 5 ‐C 5 H 4 (SiMe 3 )] 3 53 dürfte weiterhin große Schwierigkeiten bereiten.…”

Slow Magnetic Relaxation in a Trigonal Prismatic Uranium(III) Complex

“…Structure of the trigonal prismatic complex U(Ph 2 BPz 2 ) 3 (1). 8 Orange, purple, gray, and blue spheres represent U, B, C, and N atoms, respectively; H atoms have been omitted for clarity. The coordination at the U III center approximates D 3h symmetry, with U-N distances of 2.487 (7)-2.568 (7) Å and N-U-N angles of 73.2(2)-73.6(3) and 83.0(2)-95.1(2)°.…”