Systematic Investigation of Thorium(IV)– and Uranium(IV)–Ligand Bonding in Dithiophosphonate, Thioselenophosphinate, and Diselenophosphonate Complexes

Homoleptic soft-donor actinide complexes
of the general form An­[E2PROR′]4 were
synthesized from salt metathesis between ThCl4(DME)2 or UI4(1,4-dioxane)2 and M­[E2PROR′], M = Na, K, to yield 2 (An = Th, E = S,
R = 4-MeOC6H4, R′ = Me), 3 (An = Th, E = S, R = 4-MeOC6H4, R′
= tBu), 4 (An = U, E = S,
R = 4-MeOC6H4, R′ = Me), 5 (An = Th, E = Se, R = C6H5, R′ = Me),
and 6 (An = U, E = Se, R = C6H5, R′ = Me). In addition thorium and uranium thioselenophosphinate
complexes 7 and 8 were produced from the
reaction of ThCl4(DME)2 and UI4(1,4-dioxane)2 and Na­[SSePPh2], respectively. All compounds were
characterized using elemental analysis, 1H and 31P NMR, and IR spectroscopy, and the U­(IV) compounds were also examined
with UV–vis spectroscopy. The 77Se NMR spectrum
of 5 reveals the first reported resonance with a Th–Se
bond. The solid-state structures of 2, 5, 7, and 8 were determined by X-ray crystallography.
The actinide–ligand bonding was examined using density functional
theory calculations in conjunction with quantum theory of atoms-in-molecules
analysis and shows slightly increased covalency in actinide–selenium
bonds than actinide–sulfur.

通式为An[E₂PROR′]₄的全同配体软给体锕系配合物，通过ThCl₄(DME)₂或UI₄(1,4-二氧六环)₂与M[E₂PROR′]（M为钠(Na)、钾(K)）之间的复分解反应合成，得到配合物2（An=钍(Th)，E=硫(S)，R=对甲氧基苯基(4-MeOC₆H₄)，R′=甲基(Me)）、3（An=钍(Th)，E=硫(S)，R=对甲氧基苯基(4-MeOC₆H₄)，R′=叔丁基(tBu)）、4（An=铀(U)，E=硫(S)，R=对甲氧基苯基(4-MeOC₆H₄)，R′=甲基(Me)）、5（An=钍(Th)，E=硒(Se)，R=苯基(C₆H₅)，R′=甲基(Me)）以及6（An=铀(U)，E=硒(Se)，R=苯基(C₆H₅)，R′=甲基(Me)）。此外，钍与铀的硫硒代次膦酸根配合物7和8，分别由ThCl₄(DME)₂、UI₄(1,4-二氧六环)₂与Na[SSePPh₂]反应制得。所有化合物均通过元素分析、氢谱(¹H NMR)、磷谱(³¹P NMR)及红外光谱(IR spectroscopy)进行表征；其中四价铀(U(IV))类化合物还辅以紫外-可见光谱(UV–vis spectroscopy)完成分析。配合物5的硒谱(⁷⁷Se NMR)结果首次报道了含钍-硒(Th–Se)键的共振信号。配合物2、5、7与8的固态结构通过X射线晶体学（X-ray crystallography）得以解析。通过密度泛函理论（density functional theory, DFT）计算结合分子中原子量子理论（quantum theory of atoms-in-molecules, QTAIM）分析，对锕系-配体成键情况进行了研究，结果显示锕系-硒键的共价性略高于锕系-硫键。