Cerium(IV) Neopentoxide Complexes

Abstract

Treatment of ceric ammonium nitrate (CAN) with varying amounts of sodium neopentoxide led to the isolation of crystalline cerium(IV) complexes [Ce(OCH2tBu)2(NO3)2(HOCH2tBu)2], [Ce(OCH2tBu)3(NO3)-(NCCH3)]2, [Ce2(OCH2tBu)7(NO3)]2, and [Ce2(OCH2tBu)9Na-(THF)] featuring Ce(IV)/(OR) ratios of 1:2, 1:3, 1:3.5, and 1:4.5, respectively. The complexes are light-sensitive and prone to ligand redistribution as evidenced by multicomponent NMR spectra as well as the formation of [{Ce(OCH2tBu)4}2(THF)] and the mixed-valent complex [Ce3(OCH2tBu)9(NO3)2]. The CAN protocol also gave access to the isopropoxide derivative [Ce(OiPr)3(NO3)(THF)]2. The reaction of [Et4N]2[CeCl6] (CAC, ceric organoammonium chloride) with different equivalents of Na(OCH2tBu) was also impaired by ligand reorganization and ate complexation as detected for the tetravalent cerium complex [Ce2(OCH2tBu)7Cl2][Et4N]. Protonolysis of [Ce{N(SiHMe2)2}4] with 4 equiv of HOCH2tBu afforded donor-free homoleptic [Ce(OCH2tBu)4]3 in quantitative yield. All complexes were characterized by NMR, DRIFT, and UV-vis spectroscopy, as well as paramagnetic susceptibility measurements, X-ray structure analysis, and elemental analysis.