Synthesis and Structural Characterization of a Series of Carboxylic Acid Modified Cerium(III) Alkoxides

A series of cerium alkoxides were synthesized from the reaction of Ce{N[Si(CH 3 ) 3 ] 2 } 3 and the appropriate alcohol: neopentyl alcohol [H–OCH 2 C(CH 3 ) 3 = H‐ONep], tert ‐butyl alcohol [H–OC(CH 3 ) 3 = H‐O t Bu], o ‐( tert ‐butyl)phenol {H–OC 6 H 4 [C(CH 3 ) 3 ]‐2 = H‐ o BP}, 2,6‐dimethylphenol [H–OC 6 H 3 (CH 3 ) 2 ‐2,6 = H‐DMP], 2,6‐diisopropylphenol {H–OC 6 H 3 [CH(CH 3 ) 2 ] 2 ‐2,6 = H‐DIP}, 2,6‐di‐ tert ‐butylphenol {H–OC 6 H 3 [C(CH 3 ) 3 ] 2 ‐2,6 = H‐DBP}, or 2,6‐diphenylphenol [H–OC 6 H 3 (C 6 H 5 ) 2 ‐2,6 = H‐DPP] using toluene (tol), tetrahydrofuran (THF) or pyridine (py). The precursors were characterized as [Ce(μ‐ONep) 2 (ONep)] 4 ( 1 ), Ce 4 (μ 3 ‐O t Bu) 3 (μ‐O t Bu) 4 (O t Bu) 5 ( 2 ), Ce 3 (μ 3 ‐O t Bu) 3 (μ‐O t Bu) 3 (O t Bu) 3 (H‐O t Bu) 2 ( 2a ), Ce( o BP) 3 (THF) 3 ( 3 ), [Ce(μ‐DMP)(DMP) 2 (solv) 2 ] 2 [solv = THF ( 4 ) and py ( 4a )], Ce(DIP) 3 (THF) 3 ( 5 ), Ce(DPP) 3 (THF) 2 ( 6 ). Once isolated, several of these species were further reacted with a series of sterically varied carboxylic acid modifiers including isobutyric acid [H–O 2 CCH(CH 3 ) 2 = H‐OPc] and trimethylacetic acid [H–O 2 CC(CH 3 ) 3 = H‐OBc]. The products were isolated as [Ce(OR)(μ‐ORc)(μ c ‐ORc)(py)] 2 [OR = o BP, OBc: 7 ; DMP, OPc: 8 ; DMP, OBc: 9 ; DIP, OPc: 10 ]. These compounds were identified by single‐crystal X‐ray diffraction and powder XRD analyses. Several novel structure types are added to the cerium alkoxide family of compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)