Siloxides as Supporting Ligands in Uranium(III)‐Mediated Small‐Molecule Activation

Abstract

Siloxide unterstützen die Reduktion kleiner Moleküle durch Uran‐Komplexe. Die Behandlung von [U{N(SiMe3)2}3] mit HOSi(OtBu)3 (3 Äquiv.) liefert den neuartigen homoleptischen Uran(III)‐Siloxid‐Komplex 1, der als Zwei‐Elektronen‐Reduktionsmittel für CS2 und CO2 (siehe Schema) wirkt. Komplex 1 reduziert außerdem Toluol und bildet einen invertierten Diuran‐Sandwichkomplex.

Reductive assembly of cyclobutadienyl and diphosphacyclobutadienyl rings at uranium

“…This similarity in magnitude of the overlap populations for the d-and p-type interactions in 3 and 4a contrasts to the situation found in uranium-inverted sandwich complexes of arenes [25][26][27][28][29][30][31][32][33][34][35][36] and the cyclo-octatetraenide dianion, where dbonding has been shown computationally to dominate for these larger aromatic systems 26 . Germane to this point, it has been noted that d-bonding in transition metal metallocene complexes is generally weaker than in transition metal arene complexes; this is usually justified on the basis of size-matching between the metal and ligand frontier orbitals 4 .…”

“…This was followed by the landmark complex uranocene [U(Z 8 22,23 in 1994 and 1995, respectively, and these compounds still constitute the only examples of uranium-cycloheptatrienyl complexes in the literature. The first p-arene complex of uranium, [U(Z 6 -C 6 H 6 )(AlCl 4 ) 3 ], was reported by Cesari et al 24 in 1971, and more recently, diuranium arene inverted sandwich complexes have become prevalent [25][26][27][28][29][30][31][32][33][34][35][36] . However, and in contrast to the d-block, the notable exception that is absent from this series of carbocyclic p-ligands is that of cyclobutadienyl.…”

Trapping of a Highly Bent and Reduced Form of 2‐Phosphaethynolate in a Mixed‐Valence Diuranium–Triamidoamine Complex

“…Synthesis of 2 from 1 and 3 from 2. the PÀCd istance in 3 is % 0.1 longer than that in I, [9] indicating substantial charge transfer from the uranium ions to the PCO À ligand. [15] TheU À N amide (av.2.324(11) )and U À N amine (av.2.790(9) ) distances are averaged by the disorder,and towards the high end of such distances.T his most likely reflects the overall anionic charge state of the diuranium component of 3,b ut may also reflect the presence of uranium(III) character since the anion portion of 3 can be formulated as a" high spin" diuranium(III)/PCO-monoanion or am ixed-valence diuranium(III/IV)/PCO-highly-reduced "low spin" form. [12] which together with the acute P-C-O angle suggests the C-atom in 3 possess some carbene character when highly reduced by backbonding, analogously to some reduced CO 2 and CS 2 complexes.…”

A six-carbon 10π-electron aromatic system supported by group 3 metals

“…Lappert and co-workers 12 13 . For actinides, several groups reported that benzene or its derivatives can serve as a bridging ligand between two uranium centers 11,[14][15][16][17][18][19] . Magnetic susceptibility measurements, X-ray absorption near edge structure (XANES) spectroscopy and density functional theory (DFT) studies showed that most of these complexes can be described as having a benzene (or a substituted benzene) dianion bridging two U(III) centers 14,16 .…”