Comparative Insertion Reactivity of CO, CO₂, ^tBuCN, and ^tBuNC into Thorium– and Uranium–Phosphorus Bonds

Abstract

A study of the comparative reactivity of CO, CO2, tBuCN, and tBuNC with (C5Me5)2An­[P­(H)­Mes]2 (An = Th, U) has been undertaken. While CO2 and tBuNC form identical products with both metals, namely (C5Me5)2An­[κ2(O,O)-O2CPH­(Mes)]2 and (C5Me5)2An­[η2(tBuNCPMes]­(CNtBu), respectively, differing results are obtained with CO and tBuCN. The reaction of tert-butylnitrile with (C5Me5)2U­[P­(H)­Mes]2 in a 2:1 ratio leads to double insertion into the U–P bonds and elimination of H2PMes, forming the diketimido complex (C5Me5)2U­[κ2(N,N)-(NCtBu)2P­(Mes)]. This is a case in which the analogous reaction with (C5Me5)2Th­[P­(H)­Mes]2 affords a different product, (C5Me5)2Th­[PH­(Mes)]­[κ2(P,N)-N­(H)­C­(CMe3)­P­(Mes)]. The reaction of 1 atm of CO with (C5Me5)2U­[P­(H)­Mes]2 results in double insertion with proton migration from one phosphido ligand to one of the CO carbons to form (C5Me5)2U­[(κ2(O,O)-OCPMesC­(O)­(H)­P­(H)­Mes]. This is in contrast to the previously published result of the reaction between (C5Me5)2Th­[P­(H)­Mes]2 and CO, in which the product is similar, but both protons from the phosphido ligands migrate to one carbon atom, resulting in (C5Me5)2Th­[κ2(O,O)-OC­(H)2P­(Mes)­C­(O)­P­(Mes)]. Density functional theory calculations demonstrate that the mechanisms are quite similar and therefore a similar product is formed, except uranium is less acidic, and the final C–H bond formation does not occur.

Experimental and Computational Studies on a Base‐Free Terminal Uranium Phosphinidene Metallocene

“…The U−N distances are 2.245(2) Å for 12 and 2.250(3) Å for 14 , whereas the U−C distances are 2.369(3) Å for 12 and 2.353(3) Å for 14 . These structural parameters are comparable to those found in Cp* 2 U[C=P(2,4,6‐Me 3 Ph)N t Bu](CN t Bu) with the U−C distance of 2.369(4) Å, and the U−N distance of 2.293(4) Å, [17c] and Cp* 2 U[C=P(Ph)N t Bu](CN t Bu) with the U−C distance of 2.383(3) Å, and the U−N distance of 2.273(2) Å [17b] …”

Crystal structures of metallocene complexes with uranium–germanium bonds

“…Finally, the Boncella group has more recently reported a second uranium-tin bond (Winston et al, 2016). We have found that protonolysis reactions with primary pnictines have resulted in the formation of actinide-pnictido bonds (Behrle & Walensky, 2016;Vilanova et al, 2017;Tarlton et al, 2020Tarlton et al, , 2021, so we decided to utilize a secondary germane in the same strategy. However, the issue is the protonic versus hydridic nature of the E-H bonds, and hence we used 3,5-(CF 3 ) 2 C 6 H 3 -substituted germane to obtain a more protonic hydrogen.…”

Crystal structure of [Th3(Cp*)3(O)(OH)3]2Cl2(N3)6: a discrete molecular capsule built from multinuclear organothorium cluster cations

“…The increased number of Th-containing structures coincides with a renewed interest in actinide chemistry in general, and these ISSN 2056-9890 studies have revealed interesting structural features unique to Th-containing compounds such as a strong tendency of Th 4+ to form high-nuclearity yet discrete molecular complexes and ions (Wilson et al, 2007;Knope et al, 2011;Wacker et al, 2019. ) The title compound of this study was isolated during research using {Th(Cp*) 2 }-based complexes to study novel organic transformations (Tarlton et al, 2020;Tarlton, Fajen et al, 2021) and actinide-main-group bonding involving Th 4+ (Tarlton, Yang et al 2021;Rungthanaphatsophon et al, 2018;Vilanova et al, 2017). It represents an unprecedented case of overlap between organothorium chemistry and the formation of polynuclear oxo-bridged clusters.…”