Synthetic and structural studies of a series of soluble cerium(IV) alkoxide and alkoxide nitrate complexes

Abstract

The reactions of (NH4)2Ce(N03)6 (CAN) with 2-8 equiv of NaOCMe, in THF and in tert-butyl alcohol have been studied. A series of ceric alkoxide complexes of general formula Ce(OCMe,),(NO,)b(solvent),"d ( a = 1-6; b = 0-3; c = 2, 4; d = 0, 2; a + b = 4 + 6) have been identified as well as Ce2(0CMe3)9Na and Ce3(OCMe3)lo0. Interconversion of these complexes by treatment with NaOCMe, or NH4N03 has also been studied. CAN reacts with 3 equiv of NaOCMe, in THF to form Ce-(OCMe,)(NO3),(THF), (1). In tert-butyl alcohol this reaction forms the HOCMe, solvate Ce(OCMe,)(NO,),(HOCMe,), (1').1 reacts with 1 equiv of NaOCMe, and CAN reacts with 4 equiv of NaOCMe, to form Ce(OCMe3)2(N03)2(THF), (2). In tert-butyl alcohol solvent, 1' reacts with NaOCMe, to form Ce(OCMe3)2(N03)2(HOCMe ), (2'). 2' crystallizes from a concentrated toluene solution at -34 OC in space group Pi (No. 2; Ci) with a = 10.7548 (56) i, b = 11.0853 (49) A, c = 12.4403 (56) A, a = 72.760 (34)O, = 88.190 (39)O, y = 69.050 (35)O, V = 1318.0 (11) A', and Z = 2 for Ddd = 1.41 g cm-,.Least-squares refinement of the model based on 4935 observed reflections converged to RF = 7.7%. If each NO, ligand is taken to occupy just one coordination site, the structure of 2' is that of a distorted octahedron in which identical ligands are trans to each other. Ce(OCMe3),(NOo)(THF)2 (3) can be prepared from 2 or 2' and NaOCMe, or from CAN and 5 equiv of NaOCMe,. Ce(OCMe,),(THF), (4) is prepared from 3 and NaOCMe, or from CAN and 6 equiv of NaOCMe,. The reaction of 4 with 2 equiv of NaOCMe, or reaction of CAN with 8 equiv of NaOCMe, forms Ce(OCMe3)6Na2(THF)4 (5). 5 cr s t a k e s from dimethoxyethane (DME) at -34 OC as Ce (OCMe3)6Na,(DME)2 (5') in space group PnaZl with a = 20.5337 (36) i, b = 10.9557 (23) A, c = 19.4128 (38) A, V = 4367.1 (15) A', and Z = 4 for Dmld = 1.22 gLeast-squares refinement of the model based on 9092 observed reflections converged to RF = 4.9%. 5' contains a distorted-octahedral arrangement of OCMe, groups around cerium. Each sodium ion is coordinated by one DME ligand and a facial set of three OCMe, groups of the Ce(OCMe,)62-octahedron. The reaction of 4 with equiv of NaOCMe, forms Cez(OCMe3)gNa (6). Both 4 and 6 in toluene slowly form Ce,(OCMe3)lo0 (7). Complex 5 reacts with 5 equiv of NH4N03 to form 1 in quantitative yield.

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

“…The monomeric species that are solvated [17,25,48] also have a similar average Ce-OR distance of 2.17 Å. The mononuclear solvated 6 was found to be in agreement with the metrical data reported for the unsolvated but π-bound DPP; [17][18][19][20][21][22][23][24][25][26][27][28][29] the average Ce-OR distances were 2.21 Å for 5 and 2.24 Å for 6.…”

“…A similar mononuclear structural arrangement was observed for the DPP (6, Figure 8) ligated compound; however, for 6 only two THF molecules are present. The previously reported DPP derivative was also a monomer but had π interactions from the ortho phenyl groups, [17][18][19][20][21][22][23][24][25][26][27][28][29] therefore, the addition of coordinated solvent noted for 6 is not unexpected. For the Ln(DPP) 3 (THF) 2 Ln = La, [42,44] Nd, [42,44] Yb [45,46] complexes, the large trans effect of the OAr and the THF ligands was also observed for 6.…”

“…In addition, CeO x has demonstrated a wide variety of other applications, such as barrier layers, [3][4][5] counter electrodes for electrochromic glasses, [6] catalysts, [7][8][9][10][11] electrolytes for solid oxide fuel cells, [12][13][14] polishing agents for soft and hard optical glasses, [15,16] and numerous other applications. Due to the widespread use of CeO x , it is surprising that only a few structurally characterized cerium alkoxides [Ce(OR) 3 ] have been reported in the literature, [17][18][19][20][21][22][23][24][25][26][27][28][29] and no systematic studies were possible from this eclectic mix of potential precursors. Because it is critical to know the structure of the precursor to be able to optimize the properties of the final CeO x materials, it was necessary to develop a family of wellcharacterized, systematically structurally diverse Ce(OR) 3 precursors.…”

A Macrocyclic Chelator That Selectively Binds Ln4+ over Ln3+ by a Factor of 1029

“…[55][56] Molecular cerium compounds are usually stabilized in the 4+ formal oxidation state by halides 57 and hard, oxygen donor ligands such as alkoxides [58][59][60][61][62][63][64][65][66][67] and acetylacetonates. [68][69] Many "non-classical" tetravalent cerium molecules have also been prepared, including organometallic compounds, [70][71][72] amide, 65,70,[73][74][75][76][77][78] porphyrins [79][80][81][82][83] and a variety of other multidentate N-donor ligands.…”

Synthesis and Characterization of Cerium(IV) Metallocenes

“…Bu3), the latter being crystallographically characterized [28]. These complexes utilized a soluble Ce(IV) alkoxide nitrate species which is readily prepared from cerium ammonium nitrate (CAN) [18]. Following this in 2010, Anwander and Edelmann reported the oxidation of CeCp3 with PhICl2 to form Cp3CeCl [29].…”