Actinide–Pnictide (An−Pn) Bonds Spanning Non‐Metal, Metalloid, and Metal Combinations (An=U, Th; Pn=P, As, Sb, Bi)

Abstract

The synthesis and characterisation is presented of the compounds [An(TrenDMBS){Pn(SiMe3)2}] and [An(TrenTIPS){Pn(SiMe3)2}] [TrenDMBS=N(CH2CH2NSiMe2But)3, An=U, Pn=P, As, Sb, Bi; An=Th, Pn=P, As; TrenTIPS=N(CH2CH2NSiPri 3)3, An=U, Pn=P, As, Sb; An=Th, Pn=P, As, Sb]. The U−Sb and Th−Sb moieties are unprecedented examples of any kind of An−Sb molecular bond, and the U−Bi bond is the first two‐centre‐two‐electron (2c–2e) one. The Th−Bi combination was too unstable to isolate, underscoring the fragility of these linkages. However, the U−Bi complex is the heaviest 2c–2e pairing of two elements involving an actinide on a macroscopic scale under ambient conditions, and this is exceeded only by An−An pairings prepared under cryogenic matrix isolation conditions. Thermolysis and photolysis experiments suggest that the U−Pn bonds degrade by homolytic bond cleavage, whereas the more redox‐robust thorium compounds engage in an acid–base/dehydrocoupling route.

The “Hidden” Reductive [2+2+1]‐Cycloaddition Chemistry of 2‐Phosphaethynolate Revealed by Reduction of a Th‐OCP Linkage

“…This latter species in turn likely then decomposes to 4 by activating the C−H bond of the methyl group with elimination of H 2 . This is in‐line with our previous findings that 4 and its uranium analogue not only result from acid‐base deprotonations, [13] but also from low‐valent U III [U(Tren TIPS )] slowly liberating H 2 with concomitant oxidation to the U‐analogue of 4 ; [22] the corresponding thorium complex would be anticipated to be even more active in this regard.…”

Functionalization of Carbon Monoxide and tert‐Butyl Nitrile by Intramolecular Proton Transfer in a Bis(Phosphido) Thorium Complex

“…The Th–P2 (phosphido) bond of 2.9377(11) Å in 1 is similar to the 2.9406(11) Å in (Tren DMBS )AnP(SiMe 3 ) 2 , while the Th–P1 distance is slightly longer at 3.0085(12) Å. An elongation in the Th−N bond is also observed at 2.444(4) Å which is longer than most Th−N (primary amide) bonds.…”

Thorium(IV) and Uranium(IV) Phosphaazaallenes

“…For example, phosphaalkenes, P=C, have attracted interest for building blocks in organophosphorus chemistry [1][2][3], ligands to transition metal complexes [4,5], as well as potential applications as functional materials [6][7][8][9][10]. After nearly 20 years of dormancy [11][12][13][14][15], actinide-phosphorus has received greater attention recently [16][17][18][19] with researchers examining similarities and differences in the molecular and electronic structure of its more studied congener, nitrogen. Our interest in actinide-phosphido complexes has been on investigating small molecule reactivity.…”