Diphosphazide-Supported Trialkyl Thorium(IV) Complex
Tara K. K. Dickie, Ashraf A. Aborawi, Paul G. Hayes
Abstract
The potassium salt of a new ligand, KLP=N3 (2, LP=N3 = κ5-2,5-[(4-iPrC6H4)N3═PiPr2]2N(C4H2)−), that features two units of the rare phosphazide (RN3═PR3) functionality was synthesized via an incomplete Staudinger reaction between K[2,5-(iPr2P)2N(C4H2)] (1) and 4-iPrC6H4N3. The diphosphazide ligand was transferred to a thorium(IV) metal center using salt metathesis strategies, yielding LP=N3ThCl3 (3), which contains two intact and coordinated phosphazides. Reaction of complex 3 with 3 equiv of LiCH2SiMe3 resulted in formation of the trialkyl thorium species LP=N3Th(CH2SiMe3)3 (4). In contrast, attempts to synthesize an organothorium complex supported by the previously reported bisphosphinimine ligand LP=N (LP=N = κ3-2,5-[(4-iPrC6H4)N═PiPr2]2N(C4H2)−) afforded the cyclometalated dialkyl complex L*P=NTh(CH2SiMe3)2 (6, L*P═N = κ4-2-[(4-iPrC6H3)N═PiPr2]-5-[(4-iPrC6H4)N═PiPr2]N(C4H2)2–) and 1 equiv of free tetramethylsilane.