f‑Element Zintl Chemistry: Actinide-Mediated Dehydrocoupling of H2Sb1– Affords the Trithorium and Triuranium Undeca-Antimontriide Zintl Clusters [{An(TrenTIPS)}3(μ3‑Sb11)] (An = Th, U; TrenTIPS = {N(CH2CH2NSiiPr3)3}3–)

Reaction of the cesium antimonide complex [Cs­(18C6)2]­[SbH2] (1, 18C6 = 18-crown-6 ether) with the triamidoamine actinide separated ion pairs [An­(TrenTIPS)­(L)]­[BPh4] (TrenTIPS = {N­(CH2CH2NSiiPr3)3}3–; An/L = Th/DME (2Th); U/THF (2U)) affords the triactinide undeca-antimontriide Zintl clusters [{An­(TrenTIPS)}3(μ3-Sb11)] (An = Th (3Th), U (3U)) by dehydrocoupling. Clusters 3Th and 3U provide two new examples of the Sb11 3– Zintl trianion and are unprecedented examples of molecular Sb11 3– being coordinated to anything since all previous reports featured isolated Sb11 3– Zintl trianions in separated ion quadruple formulations with noncoordinating cations. Quantum chemical calculations describe dominant ionic An–Sb interactions in 3Th and 3U, though the data suggest that the latter exhibits slightly more covalent An–Sb linkages than the former. Complexes 3Th and 3U have been characterized by single crystal X-ray diffraction, NMR, IR, and UV/vis/NIR spectroscopies, elemental analysis, and quantum chemical calculations.