First Structurally Characterized Actinide Isocyanates

Abstract

The synthesis and characterization of the neutral uranylisocyanate UO(2)(NCO)(2)(OP(NMe(2))(3))(2) [crystal data: monoclinic, P2(1)/c, a = 8.512(2) A, b = 10.931(2) A, c = 14.329(3) A, beta = 103.923(3) degrees , V = 1294.0(4) A(3), Z = 2] and isocyanato uranate (Et(4)N)(6)[(UO(2))(2)(NCO)(5)O](2) x 2CH(3)CN x H(2)O [crystal data: monoclinic, P2(1)/c, a = 17.2787(2) A, b = 15.560(1) A, c = 32.7619(4) A, beta = 94.0849(5) degrees , V = 8786.5(2) A(3), Z = 4] are reported. Not only are these compounds the first unambiguously characterized uranium isocyanates regardless of the oxidation state for uranium, but they are also the first structurally characterized actinide isocyanates. Both compounds show coordination of the OCN moiety through nitrogen to uranium and were characterized using IR and (1)H, (13)C, (14)N, and (31)P NMR spectroscopy and X-ray diffraction.

Synthesis, structure, spectroscopy and redox energetics of a series of uranium(IV) mixed-ligand metallocene complexes

“…2. Compound 6 represents a rare example of a structurally characterized actinide isocyanate complex, of which there are only two other known complexes [31,32]. Both complexes 2 and 6 feature a bent-metallocene framework with the amide and chloride (for 2) or isocyanate (for 6) ligands contained within the metallocene wedge.…”

UN213−: A Structurally Characterized Binary Actinide Heptaazide Anion

“…Detailed discussions of the chemistry of covalent azides are available in excellent review articles by Dehnicke [12] and Klapötke et al [9] Since salts containing the binary azide anions are generally more thermally stable and less explosive, particularly when large bulky cations are employed, we set out to investigate the synthesis of a binary uranium azide anion. The convenient synthesis of the (R 4 N) 2 [UX 6 ] (R = alkyl; X = Cl, Br) salts, [13] as well as the previous reports on the synthesis and structural characterization of salts of the octaisothiocyanatouranate anion U(NCS) 8 4À , [14] made the synthesis of a uranium(iv) azide a particularly interesting and promising target. Herein, we report on the synthesis and characterization including the single-crystal structure determination of the binary uranium(iv) heptaazide anion in the (Bu 4 N) 3 …”

“…The N a atoms of six of the azide ligands are positioned at the corners of a trigonal antiprism, whereas the seventh azide group is located along the C 3 axis. The UÀN bond lengths in 1 a range from 2.32(2) to 2.40 (2) , and it is worth noting that the shortest anion-anion contact, between N6 and N3…”

“…1 a: An alternative procedure using (Bu 4 N) 2 [UCl 6 ] instead of (Bu 4 N) 2 [UBr 6 ] and acetonitrile instead of CH 3 CH 2 CN was also employed. After the volume of CH 3 CN had been reduced in the reaction vessel under vacuum to form a saturated solution, CFCl 3 (20 mL) was added under an argon purge, and the vessel was then cooled to À28 8C, whereby emerald green crystals formed in low yield.…”

Uranyl complexation by monodentate nitrogen donor ligands. A relativistic density functional study

“…Complexation by Ph 3 PNH was demonstrated to be favorable when compared with the corresponding O-donor ligand [16]. NCO has been shown to coordinate preferentially via the N center [17]. Thus, for most of the monodentate Ndonor functional groups listed above, simple model complexes, which may serve as reference for the corresponding groups of humic substances, seem to be unknown.…”