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-).

Abstract

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 Sb113- Zintl trianion and are unprecedented examples of molecular Sb113- being coordinated to anything since all previous reports featured isolated Sb113- 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.