Uranium(III) and uranium(IV) meta-terphenyl thiolate complexes

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posted on 2025-07-31, 16:11 authored by Conrad GoodwinConrad Goodwin

See: 10.1021/acs.inorgchem.4c03085We report the synthesis and characterization of crystalline m-terphenylthiolate uranium complexes supported by the bulky ligand system, SAriPr6 (SAriPr6 = {SC6H3-2,6-(Tripp)2}; Tripp = 2,4,6-iPr-C6H2). Treatment of UIVCl4 with 2 equiv of KSAriPr6 in Et2O afforded both [UIV(SAriPr6)2(Cl)2] (1) and the Et2O adduct, [UIV(SAriPr6)2(Cl)2(Et2O)2] (1·Et2O) in poor yield. The reaction between [UIV(BH4)4] and 1 equiv of KSAriPr6 in toluene gave several crystals of the double salt, [UIV(μ-SAriPr6)(BH4)2(μ-BH4)(μ3-BH4)K]2 (2), and exposing the crude reaction mixture to Et2O gave the disulfide dimer, (SAriPr6)2. The reaction between [UIV(BH4)4] and 1 equiv of HSAriPr6 in hot toluene gave [UIII(H3B·SAriPr6 κS,H,H)(BH4)2] (3) which proved resistant to further substitution using either HSAriPr6 or KSAriPr6. Two U(III) mono-terphenylthiolates, [UIII(SAriPr6)(BH4)2] (4a) and [{UIII(SAriPr6)(BH4)}2{μ-B2H6}] (4b), were isolated as a mixture from the reaction between [UIII(BH3)3(toluene)] and 1 equiv of KSAriPr6, while using 2 equiv of KSAriPr6 gave the bis-terphenylthiolate complex [UIII(SAriPr6)2(BH4)] (5). Complex 4b is a rare example of a nido-metalloborane. Complexes 1–5 have been characterized variously by single-crystal and powder X-ray diffraction, multinuclear NMR spectroscopy, infrared spectroscopy, UV–Vis–NIR spectroscopy, SQUID magnetometry, and elemental analyses as appropriate. Quantum chemical calculations have been employed to interpret the nature of the U–S bonding interactions across these complexes.